8120 lines
231 KiB
C
8120 lines
231 KiB
C
/* Global common subexpression elimination/Partial redundancy elimination
|
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and global constant/copy propagation for GNU compiler.
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Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
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Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
|
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the terms of the GNU General Public License as published by the Free
|
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Software Foundation; either version 2, or (at your option) any later
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version.
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||
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
|
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
|
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
|
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for more details.
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||
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You should have received a copy of the GNU General Public License
|
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along with GCC; see the file COPYING. If not, write to the Free
|
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Software Foundation, 59 Temple Place - Suite 330, Boston, MA
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02111-1307, USA. */
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/* TODO
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- reordering of memory allocation and freeing to be more space efficient
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- do rough calc of how many regs are needed in each block, and a rough
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calc of how many regs are available in each class and use that to
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throttle back the code in cases where RTX_COST is minimal.
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- a store to the same address as a load does not kill the load if the
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source of the store is also the destination of the load. Handling this
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allows more load motion, particularly out of loops.
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- ability to realloc sbitmap vectors would allow one initial computation
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of reg_set_in_block with only subsequent additions, rather than
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recomputing it for each pass
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*/
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/* References searched while implementing this.
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Compilers Principles, Techniques and Tools
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Aho, Sethi, Ullman
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Addison-Wesley, 1988
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Global Optimization by Suppression of Partial Redundancies
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E. Morel, C. Renvoise
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communications of the acm, Vol. 22, Num. 2, Feb. 1979
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||
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A Portable Machine-Independent Global Optimizer - Design and Measurements
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||
Frederick Chow
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Stanford Ph.D. thesis, Dec. 1983
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||
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A Fast Algorithm for Code Movement Optimization
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D.M. Dhamdhere
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SIGPLAN Notices, Vol. 23, Num. 10, Oct. 1988
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||
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A Solution to a Problem with Morel and Renvoise's
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Global Optimization by Suppression of Partial Redundancies
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K-H Drechsler, M.P. Stadel
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ACM TOPLAS, Vol. 10, Num. 4, Oct. 1988
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Practical Adaptation of the Global Optimization
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Algorithm of Morel and Renvoise
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D.M. Dhamdhere
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ACM TOPLAS, Vol. 13, Num. 2. Apr. 1991
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Efficiently Computing Static Single Assignment Form and the Control
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Dependence Graph
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R. Cytron, J. Ferrante, B.K. Rosen, M.N. Wegman, and F.K. Zadeck
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ACM TOPLAS, Vol. 13, Num. 4, Oct. 1991
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||
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Lazy Code Motion
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J. Knoop, O. Ruthing, B. Steffen
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ACM SIGPLAN Notices Vol. 27, Num. 7, Jul. 1992, '92 Conference on PLDI
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What's In a Region? Or Computing Control Dependence Regions in Near-Linear
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Time for Reducible Flow Control
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Thomas Ball
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ACM Letters on Programming Languages and Systems,
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Vol. 2, Num. 1-4, Mar-Dec 1993
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An Efficient Representation for Sparse Sets
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Preston Briggs, Linda Torczon
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ACM Letters on Programming Languages and Systems,
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Vol. 2, Num. 1-4, Mar-Dec 1993
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A Variation of Knoop, Ruthing, and Steffen's Lazy Code Motion
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K-H Drechsler, M.P. Stadel
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ACM SIGPLAN Notices, Vol. 28, Num. 5, May 1993
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Partial Dead Code Elimination
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J. Knoop, O. Ruthing, B. Steffen
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ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
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Effective Partial Redundancy Elimination
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P. Briggs, K.D. Cooper
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ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
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The Program Structure Tree: Computing Control Regions in Linear Time
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R. Johnson, D. Pearson, K. Pingali
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ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
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||
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Optimal Code Motion: Theory and Practice
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J. Knoop, O. Ruthing, B. Steffen
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ACM TOPLAS, Vol. 16, Num. 4, Jul. 1994
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The power of assignment motion
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J. Knoop, O. Ruthing, B. Steffen
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ACM SIGPLAN Notices Vol. 30, Num. 6, Jun. 1995, '95 Conference on PLDI
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Global code motion / global value numbering
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C. Click
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ACM SIGPLAN Notices Vol. 30, Num. 6, Jun. 1995, '95 Conference on PLDI
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Value Driven Redundancy Elimination
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L.T. Simpson
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Rice University Ph.D. thesis, Apr. 1996
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Value Numbering
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L.T. Simpson
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Massively Scalar Compiler Project, Rice University, Sep. 1996
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High Performance Compilers for Parallel Computing
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Michael Wolfe
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Addison-Wesley, 1996
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Advanced Compiler Design and Implementation
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Steven Muchnick
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Morgan Kaufmann, 1997
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Building an Optimizing Compiler
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Robert Morgan
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Digital Press, 1998
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People wishing to speed up the code here should read:
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Elimination Algorithms for Data Flow Analysis
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B.G. Ryder, M.C. Paull
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ACM Computing Surveys, Vol. 18, Num. 3, Sep. 1986
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How to Analyze Large Programs Efficiently and Informatively
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D.M. Dhamdhere, B.K. Rosen, F.K. Zadeck
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ACM SIGPLAN Notices Vol. 27, Num. 7, Jul. 1992, '92 Conference on PLDI
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People wishing to do something different can find various possibilities
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in the above papers and elsewhere.
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*/
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#include "config.h"
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#include "system.h"
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#include "coretypes.h"
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#include "tm.h"
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#include "toplev.h"
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#include "rtl.h"
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#include "tree.h"
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#include "tm_p.h"
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#include "regs.h"
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#include "hard-reg-set.h"
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#include "flags.h"
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#include "real.h"
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#include "insn-config.h"
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#include "recog.h"
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#include "basic-block.h"
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#include "output.h"
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#include "function.h"
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#include "expr.h"
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#include "except.h"
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#include "ggc.h"
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#include "params.h"
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#include "cselib.h"
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#include "intl.h"
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#include "obstack.h"
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/* Propagate flow information through back edges and thus enable PRE's
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moving loop invariant calculations out of loops.
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Originally this tended to create worse overall code, but several
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improvements during the development of PRE seem to have made following
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back edges generally a win.
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Note much of the loop invariant code motion done here would normally
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be done by loop.c, which has more heuristics for when to move invariants
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out of loops. At some point we might need to move some of those
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heuristics into gcse.c. */
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/* We support GCSE via Partial Redundancy Elimination. PRE optimizations
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are a superset of those done by GCSE.
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We perform the following steps:
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1) Compute basic block information.
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2) Compute table of places where registers are set.
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3) Perform copy/constant propagation.
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4) Perform global cse.
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5) Perform another pass of copy/constant propagation.
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Two passes of copy/constant propagation are done because the first one
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enables more GCSE and the second one helps to clean up the copies that
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GCSE creates. This is needed more for PRE than for Classic because Classic
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GCSE will try to use an existing register containing the common
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subexpression rather than create a new one. This is harder to do for PRE
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because of the code motion (which Classic GCSE doesn't do).
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Expressions we are interested in GCSE-ing are of the form
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(set (pseudo-reg) (expression)).
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Function want_to_gcse_p says what these are.
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PRE handles moving invariant expressions out of loops (by treating them as
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partially redundant).
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Eventually it would be nice to replace cse.c/gcse.c with SSA (static single
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assignment) based GVN (global value numbering). L. T. Simpson's paper
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(Rice University) on value numbering is a useful reference for this.
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**********************
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We used to support multiple passes but there are diminishing returns in
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doing so. The first pass usually makes 90% of the changes that are doable.
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A second pass can make a few more changes made possible by the first pass.
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Experiments show any further passes don't make enough changes to justify
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the expense.
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A study of spec92 using an unlimited number of passes:
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[1 pass] = 1208 substitutions, [2] = 577, [3] = 202, [4] = 192, [5] = 83,
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[6] = 34, [7] = 17, [8] = 9, [9] = 4, [10] = 4, [11] = 2,
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[12] = 2, [13] = 1, [15] = 1, [16] = 2, [41] = 1
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It was found doing copy propagation between each pass enables further
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substitutions.
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PRE is quite expensive in complicated functions because the DFA can take
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awhile to converge. Hence we only perform one pass. The parameter max-gcse-passes can
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be modified if one wants to experiment.
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**********************
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The steps for PRE are:
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1) Build the hash table of expressions we wish to GCSE (expr_hash_table).
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2) Perform the data flow analysis for PRE.
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3) Delete the redundant instructions
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4) Insert the required copies [if any] that make the partially
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redundant instructions fully redundant.
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5) For other reaching expressions, insert an instruction to copy the value
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to a newly created pseudo that will reach the redundant instruction.
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The deletion is done first so that when we do insertions we
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know which pseudo reg to use.
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Various papers have argued that PRE DFA is expensive (O(n^2)) and others
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argue it is not. The number of iterations for the algorithm to converge
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is typically 2-4 so I don't view it as that expensive (relatively speaking).
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PRE GCSE depends heavily on the second CSE pass to clean up the copies
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we create. To make an expression reach the place where it's redundant,
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the result of the expression is copied to a new register, and the redundant
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expression is deleted by replacing it with this new register. Classic GCSE
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doesn't have this problem as much as it computes the reaching defs of
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each register in each block and thus can try to use an existing register.
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**********************
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A fair bit of simplicity is created by creating small functions for simple
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tasks, even when the function is only called in one place. This may
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measurably slow things down [or may not] by creating more function call
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overhead than is necessary. The source is laid out so that it's trivial
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to make the affected functions inline so that one can measure what speed
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up, if any, can be achieved, and maybe later when things settle things can
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be rearranged.
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Help stamp out big monolithic functions! */
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/* GCSE global vars. */
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/* -dG dump file. */
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static FILE *gcse_file;
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/* Note whether or not we should run jump optimization after gcse. We
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want to do this for two cases.
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* If we changed any jumps via cprop.
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* If we added any labels via edge splitting. */
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static int run_jump_opt_after_gcse;
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/* Bitmaps are normally not included in debugging dumps.
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However it's useful to be able to print them from GDB.
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We could create special functions for this, but it's simpler to
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just allow passing stderr to the dump_foo fns. Since stderr can
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be a macro, we store a copy here. */
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static FILE *debug_stderr;
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/* An obstack for our working variables. */
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static struct obstack gcse_obstack;
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struct reg_use {rtx reg_rtx; };
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/* Hash table of expressions. */
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struct expr
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{
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/* The expression (SET_SRC for expressions, PATTERN for assignments). */
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rtx expr;
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/* Index in the available expression bitmaps. */
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int bitmap_index;
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/* Next entry with the same hash. */
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struct expr *next_same_hash;
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/* List of anticipatable occurrences in basic blocks in the function.
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An "anticipatable occurrence" is one that is the first occurrence in the
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basic block, the operands are not modified in the basic block prior
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to the occurrence and the output is not used between the start of
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the block and the occurrence. */
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struct occr *antic_occr;
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/* List of available occurrence in basic blocks in the function.
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An "available occurrence" is one that is the last occurrence in the
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basic block and the operands are not modified by following statements in
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the basic block [including this insn]. */
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struct occr *avail_occr;
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/* Non-null if the computation is PRE redundant.
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The value is the newly created pseudo-reg to record a copy of the
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expression in all the places that reach the redundant copy. */
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rtx reaching_reg;
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};
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/* Occurrence of an expression.
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There is one per basic block. If a pattern appears more than once the
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last appearance is used [or first for anticipatable expressions]. */
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struct occr
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{
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/* Next occurrence of this expression. */
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struct occr *next;
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/* The insn that computes the expression. */
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rtx insn;
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/* Nonzero if this [anticipatable] occurrence has been deleted. */
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char deleted_p;
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/* Nonzero if this [available] occurrence has been copied to
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reaching_reg. */
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/* ??? This is mutually exclusive with deleted_p, so they could share
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the same byte. */
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char copied_p;
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};
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/* Expression and copy propagation hash tables.
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Each hash table is an array of buckets.
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??? It is known that if it were an array of entries, structure elements
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`next_same_hash' and `bitmap_index' wouldn't be necessary. However, it is
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not clear whether in the final analysis a sufficient amount of memory would
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be saved as the size of the available expression bitmaps would be larger
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[one could build a mapping table without holes afterwards though].
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Someday I'll perform the computation and figure it out. */
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struct hash_table
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{
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/* The table itself.
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This is an array of `expr_hash_table_size' elements. */
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struct expr **table;
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/* Size of the hash table, in elements. */
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unsigned int size;
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||
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/* Number of hash table elements. */
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unsigned int n_elems;
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/* Whether the table is expression of copy propagation one. */
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int set_p;
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};
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/* Expression hash table. */
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static struct hash_table expr_hash_table;
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/* Copy propagation hash table. */
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static struct hash_table set_hash_table;
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/* Mapping of uids to cuids.
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Only real insns get cuids. */
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static int *uid_cuid;
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/* Highest UID in UID_CUID. */
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static int max_uid;
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/* Get the cuid of an insn. */
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#ifdef ENABLE_CHECKING
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#define INSN_CUID(INSN) (INSN_UID (INSN) > max_uid ? (abort (), 0) : uid_cuid[INSN_UID (INSN)])
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#else
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#define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)])
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#endif
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/* Number of cuids. */
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static int max_cuid;
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/* Mapping of cuids to insns. */
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static rtx *cuid_insn;
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/* Get insn from cuid. */
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#define CUID_INSN(CUID) (cuid_insn[CUID])
|
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|
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/* Maximum register number in function prior to doing gcse + 1.
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Registers created during this pass have regno >= max_gcse_regno.
|
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This is named with "gcse" to not collide with global of same name. */
|
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static unsigned int max_gcse_regno;
|
||
|
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/* Table of registers that are modified.
|
||
|
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For each register, each element is a list of places where the pseudo-reg
|
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is set.
|
||
|
||
For simplicity, GCSE is done on sets of pseudo-regs only. PRE GCSE only
|
||
requires knowledge of which blocks kill which regs [and thus could use
|
||
a bitmap instead of the lists `reg_set_table' uses].
|
||
|
||
`reg_set_table' and could be turned into an array of bitmaps (num-bbs x
|
||
num-regs) [however perhaps it may be useful to keep the data as is]. One
|
||
advantage of recording things this way is that `reg_set_table' is fairly
|
||
sparse with respect to pseudo regs but for hard regs could be fairly dense
|
||
[relatively speaking]. And recording sets of pseudo-regs in lists speeds
|
||
up functions like compute_transp since in the case of pseudo-regs we only
|
||
need to iterate over the number of times a pseudo-reg is set, not over the
|
||
number of basic blocks [clearly there is a bit of a slow down in the cases
|
||
where a pseudo is set more than once in a block, however it is believed
|
||
that the net effect is to speed things up]. This isn't done for hard-regs
|
||
because recording call-clobbered hard-regs in `reg_set_table' at each
|
||
function call can consume a fair bit of memory, and iterating over
|
||
hard-regs stored this way in compute_transp will be more expensive. */
|
||
|
||
typedef struct reg_set
|
||
{
|
||
/* The next setting of this register. */
|
||
struct reg_set *next;
|
||
/* The insn where it was set. */
|
||
rtx insn;
|
||
} reg_set;
|
||
|
||
static reg_set **reg_set_table;
|
||
|
||
/* Size of `reg_set_table'.
|
||
The table starts out at max_gcse_regno + slop, and is enlarged as
|
||
necessary. */
|
||
static int reg_set_table_size;
|
||
|
||
/* Amount to grow `reg_set_table' by when it's full. */
|
||
#define REG_SET_TABLE_SLOP 100
|
||
|
||
/* This is a list of expressions which are MEMs and will be used by load
|
||
or store motion.
|
||
Load motion tracks MEMs which aren't killed by
|
||
anything except itself. (ie, loads and stores to a single location).
|
||
We can then allow movement of these MEM refs with a little special
|
||
allowance. (all stores copy the same value to the reaching reg used
|
||
for the loads). This means all values used to store into memory must have
|
||
no side effects so we can re-issue the setter value.
|
||
Store Motion uses this structure as an expression table to track stores
|
||
which look interesting, and might be moveable towards the exit block. */
|
||
|
||
struct ls_expr
|
||
{
|
||
struct expr * expr; /* Gcse expression reference for LM. */
|
||
rtx pattern; /* Pattern of this mem. */
|
||
rtx pattern_regs; /* List of registers mentioned by the mem. */
|
||
rtx loads; /* INSN list of loads seen. */
|
||
rtx stores; /* INSN list of stores seen. */
|
||
struct ls_expr * next; /* Next in the list. */
|
||
int invalid; /* Invalid for some reason. */
|
||
int index; /* If it maps to a bitmap index. */
|
||
unsigned int hash_index; /* Index when in a hash table. */
|
||
rtx reaching_reg; /* Register to use when re-writing. */
|
||
};
|
||
|
||
/* Array of implicit set patterns indexed by basic block index. */
|
||
static rtx *implicit_sets;
|
||
|
||
/* Head of the list of load/store memory refs. */
|
||
static struct ls_expr * pre_ldst_mems = NULL;
|
||
|
||
/* Bitmap containing one bit for each register in the program.
|
||
Used when performing GCSE to track which registers have been set since
|
||
the start of the basic block. */
|
||
static regset reg_set_bitmap;
|
||
|
||
/* For each block, a bitmap of registers set in the block.
|
||
This is used by expr_killed_p and compute_transp.
|
||
It is computed during hash table computation and not by compute_sets
|
||
as it includes registers added since the last pass (or between cprop and
|
||
gcse) and it's currently not easy to realloc sbitmap vectors. */
|
||
static sbitmap *reg_set_in_block;
|
||
|
||
/* Array, indexed by basic block number for a list of insns which modify
|
||
memory within that block. */
|
||
static rtx * modify_mem_list;
|
||
bitmap modify_mem_list_set;
|
||
|
||
/* This array parallels modify_mem_list, but is kept canonicalized. */
|
||
static rtx * canon_modify_mem_list;
|
||
bitmap canon_modify_mem_list_set;
|
||
/* Various variables for statistics gathering. */
|
||
|
||
/* Memory used in a pass.
|
||
This isn't intended to be absolutely precise. Its intent is only
|
||
to keep an eye on memory usage. */
|
||
static int bytes_used;
|
||
|
||
/* GCSE substitutions made. */
|
||
static int gcse_subst_count;
|
||
/* Number of copy instructions created. */
|
||
static int gcse_create_count;
|
||
/* Number of constants propagated. */
|
||
static int const_prop_count;
|
||
/* Number of copys propagated. */
|
||
static int copy_prop_count;
|
||
|
||
/* These variables are used by classic GCSE.
|
||
Normally they'd be defined a bit later, but `rd_gen' needs to
|
||
be declared sooner. */
|
||
|
||
/* Each block has a bitmap of each type.
|
||
The length of each blocks bitmap is:
|
||
|
||
max_cuid - for reaching definitions
|
||
n_exprs - for available expressions
|
||
|
||
Thus we view the bitmaps as 2 dimensional arrays. i.e.
|
||
rd_kill[block_num][cuid_num]
|
||
ae_kill[block_num][expr_num] */
|
||
|
||
/* For reaching defs */
|
||
static sbitmap *rd_kill, *rd_gen, *reaching_defs, *rd_out;
|
||
|
||
/* for available exprs */
|
||
static sbitmap *ae_kill, *ae_gen, *ae_in, *ae_out;
|
||
|
||
/* Objects of this type are passed around by the null-pointer check
|
||
removal routines. */
|
||
struct null_pointer_info
|
||
{
|
||
/* The basic block being processed. */
|
||
basic_block current_block;
|
||
/* The first register to be handled in this pass. */
|
||
unsigned int min_reg;
|
||
/* One greater than the last register to be handled in this pass. */
|
||
unsigned int max_reg;
|
||
sbitmap *nonnull_local;
|
||
sbitmap *nonnull_killed;
|
||
};
|
||
|
||
static void compute_can_copy (void);
|
||
static void *gmalloc (size_t) ATTRIBUTE_MALLOC;
|
||
static void *gcalloc (size_t, size_t) ATTRIBUTE_MALLOC;
|
||
static void *grealloc (void *, size_t);
|
||
static void *gcse_alloc (unsigned long);
|
||
static void alloc_gcse_mem (rtx);
|
||
static void free_gcse_mem (void);
|
||
static void alloc_reg_set_mem (int);
|
||
static void free_reg_set_mem (void);
|
||
static int get_bitmap_width (int, int, int);
|
||
static void record_one_set (int, rtx);
|
||
static void replace_one_set (int, rtx, rtx);
|
||
static void record_set_info (rtx, rtx, void *);
|
||
static void compute_sets (rtx);
|
||
static void hash_scan_insn (rtx, struct hash_table *, int);
|
||
static void hash_scan_set (rtx, rtx, struct hash_table *);
|
||
static void hash_scan_clobber (rtx, rtx, struct hash_table *);
|
||
static void hash_scan_call (rtx, rtx, struct hash_table *);
|
||
static int want_to_gcse_p (rtx);
|
||
static bool gcse_constant_p (rtx);
|
||
static int oprs_unchanged_p (rtx, rtx, int);
|
||
static int oprs_anticipatable_p (rtx, rtx);
|
||
static int oprs_available_p (rtx, rtx);
|
||
static void insert_expr_in_table (rtx, enum machine_mode, rtx, int, int,
|
||
struct hash_table *);
|
||
static void insert_set_in_table (rtx, rtx, struct hash_table *);
|
||
static unsigned int hash_expr (rtx, enum machine_mode, int *, int);
|
||
static unsigned int hash_expr_1 (rtx, enum machine_mode, int *);
|
||
static unsigned int hash_string_1 (const char *);
|
||
static unsigned int hash_set (int, int);
|
||
static int expr_equiv_p (rtx, rtx);
|
||
static void record_last_reg_set_info (rtx, int);
|
||
static void record_last_mem_set_info (rtx);
|
||
static void record_last_set_info (rtx, rtx, void *);
|
||
static void compute_hash_table (struct hash_table *);
|
||
static void alloc_hash_table (int, struct hash_table *, int);
|
||
static void free_hash_table (struct hash_table *);
|
||
static void compute_hash_table_work (struct hash_table *);
|
||
static void dump_hash_table (FILE *, const char *, struct hash_table *);
|
||
static struct expr *lookup_expr (rtx, struct hash_table *);
|
||
static struct expr *lookup_set (unsigned int, struct hash_table *);
|
||
static struct expr *next_set (unsigned int, struct expr *);
|
||
static void reset_opr_set_tables (void);
|
||
static int oprs_not_set_p (rtx, rtx);
|
||
static void mark_call (rtx);
|
||
static void mark_set (rtx, rtx);
|
||
static void mark_clobber (rtx, rtx);
|
||
static void mark_oprs_set (rtx);
|
||
static void alloc_cprop_mem (int, int);
|
||
static void free_cprop_mem (void);
|
||
static void compute_transp (rtx, int, sbitmap *, int);
|
||
static void compute_transpout (void);
|
||
static void compute_local_properties (sbitmap *, sbitmap *, sbitmap *,
|
||
struct hash_table *);
|
||
static void compute_cprop_data (void);
|
||
static void find_used_regs (rtx *, void *);
|
||
static int try_replace_reg (rtx, rtx, rtx);
|
||
static struct expr *find_avail_set (int, rtx);
|
||
static int cprop_jump (basic_block, rtx, rtx, rtx, rtx);
|
||
static void mems_conflict_for_gcse_p (rtx, rtx, void *);
|
||
static int load_killed_in_block_p (basic_block, int, rtx, int);
|
||
static void canon_list_insert (rtx, rtx, void *);
|
||
static int cprop_insn (rtx, int);
|
||
static int cprop (int);
|
||
static void find_implicit_sets (void);
|
||
static int one_cprop_pass (int, int, int);
|
||
static bool constprop_register (rtx, rtx, rtx, int);
|
||
static struct expr *find_bypass_set (int, int);
|
||
static bool reg_killed_on_edge (rtx, edge);
|
||
static int bypass_block (basic_block, rtx, rtx);
|
||
static int bypass_conditional_jumps (void);
|
||
static void alloc_pre_mem (int, int);
|
||
static void free_pre_mem (void);
|
||
static void compute_pre_data (void);
|
||
static int pre_expr_reaches_here_p (basic_block, struct expr *,
|
||
basic_block);
|
||
static void insert_insn_end_bb (struct expr *, basic_block, int);
|
||
static void pre_insert_copy_insn (struct expr *, rtx);
|
||
static void pre_insert_copies (void);
|
||
static int pre_delete (void);
|
||
static int pre_gcse (void);
|
||
static int one_pre_gcse_pass (int);
|
||
static void add_label_notes (rtx, rtx);
|
||
static void alloc_code_hoist_mem (int, int);
|
||
static void free_code_hoist_mem (void);
|
||
static void compute_code_hoist_vbeinout (void);
|
||
static void compute_code_hoist_data (void);
|
||
static int hoist_expr_reaches_here_p (basic_block, int, basic_block, char *);
|
||
static void hoist_code (void);
|
||
static int one_code_hoisting_pass (void);
|
||
static void alloc_rd_mem (int, int);
|
||
static void free_rd_mem (void);
|
||
static void handle_rd_kill_set (rtx, int, basic_block);
|
||
static void compute_kill_rd (void);
|
||
static void compute_rd (void);
|
||
static void alloc_avail_expr_mem (int, int);
|
||
static void free_avail_expr_mem (void);
|
||
static void compute_ae_gen (struct hash_table *);
|
||
static int expr_killed_p (rtx, basic_block);
|
||
static void compute_ae_kill (sbitmap *, sbitmap *, struct hash_table *);
|
||
static int expr_reaches_here_p (struct occr *, struct expr *, basic_block,
|
||
int);
|
||
static rtx computing_insn (struct expr *, rtx);
|
||
static int def_reaches_here_p (rtx, rtx);
|
||
static int can_disregard_other_sets (struct reg_set **, rtx, int);
|
||
static int handle_avail_expr (rtx, struct expr *);
|
||
static int classic_gcse (void);
|
||
static int one_classic_gcse_pass (int);
|
||
static void invalidate_nonnull_info (rtx, rtx, void *);
|
||
static int delete_null_pointer_checks_1 (unsigned int *, sbitmap *, sbitmap *,
|
||
struct null_pointer_info *);
|
||
static rtx process_insert_insn (struct expr *);
|
||
static int pre_edge_insert (struct edge_list *, struct expr **);
|
||
static int expr_reaches_here_p_work (struct occr *, struct expr *,
|
||
basic_block, int, char *);
|
||
static int pre_expr_reaches_here_p_work (basic_block, struct expr *,
|
||
basic_block, char *);
|
||
static struct ls_expr * ldst_entry (rtx);
|
||
static void free_ldst_entry (struct ls_expr *);
|
||
static void free_ldst_mems (void);
|
||
static void print_ldst_list (FILE *);
|
||
static struct ls_expr * find_rtx_in_ldst (rtx);
|
||
static int enumerate_ldsts (void);
|
||
static inline struct ls_expr * first_ls_expr (void);
|
||
static inline struct ls_expr * next_ls_expr (struct ls_expr *);
|
||
static int simple_mem (rtx);
|
||
static void invalidate_any_buried_refs (rtx);
|
||
static void compute_ld_motion_mems (void);
|
||
static void trim_ld_motion_mems (void);
|
||
static void update_ld_motion_stores (struct expr *);
|
||
static void reg_set_info (rtx, rtx, void *);
|
||
static void reg_clear_last_set (rtx, rtx, void *);
|
||
static bool store_ops_ok (rtx, int *);
|
||
static rtx extract_mentioned_regs (rtx);
|
||
static rtx extract_mentioned_regs_helper (rtx, rtx);
|
||
static void find_moveable_store (rtx, int *, int *);
|
||
static int compute_store_table (void);
|
||
static bool load_kills_store (rtx, rtx, int);
|
||
static bool find_loads (rtx, rtx, int);
|
||
static bool store_killed_in_insn (rtx, rtx, rtx, int);
|
||
static bool store_killed_after (rtx, rtx, rtx, basic_block, int *, rtx *);
|
||
static bool store_killed_before (rtx, rtx, rtx, basic_block, int *);
|
||
static void build_store_vectors (void);
|
||
static void insert_insn_start_bb (rtx, basic_block);
|
||
static int insert_store (struct ls_expr *, edge);
|
||
static void remove_reachable_equiv_notes (basic_block, struct ls_expr *);
|
||
static void replace_store_insn (rtx, rtx, basic_block, struct ls_expr *);
|
||
static void delete_store (struct ls_expr *, basic_block);
|
||
static void free_store_memory (void);
|
||
static void store_motion (void);
|
||
static void free_insn_expr_list_list (rtx *);
|
||
static void clear_modify_mem_tables (void);
|
||
static void free_modify_mem_tables (void);
|
||
static rtx gcse_emit_move_after (rtx, rtx, rtx);
|
||
static void local_cprop_find_used_regs (rtx *, void *);
|
||
static bool do_local_cprop (rtx, rtx, int, rtx*);
|
||
static bool adjust_libcall_notes (rtx, rtx, rtx, rtx*);
|
||
static void local_cprop_pass (int);
|
||
static bool is_too_expensive (const char *);
|
||
|
||
|
||
/* Entry point for global common subexpression elimination.
|
||
F is the first instruction in the function. */
|
||
|
||
int
|
||
gcse_main (rtx f, FILE *file)
|
||
{
|
||
int changed, pass;
|
||
/* Bytes used at start of pass. */
|
||
int initial_bytes_used;
|
||
/* Maximum number of bytes used by a pass. */
|
||
int max_pass_bytes;
|
||
/* Point to release obstack data from for each pass. */
|
||
char *gcse_obstack_bottom;
|
||
|
||
/* We do not construct an accurate cfg in functions which call
|
||
setjmp, so just punt to be safe. */
|
||
if (current_function_calls_setjmp)
|
||
return 0;
|
||
|
||
/* Assume that we do not need to run jump optimizations after gcse. */
|
||
run_jump_opt_after_gcse = 0;
|
||
|
||
/* For calling dump_foo fns from gdb. */
|
||
debug_stderr = stderr;
|
||
gcse_file = file;
|
||
|
||
/* Identify the basic block information for this function, including
|
||
successors and predecessors. */
|
||
max_gcse_regno = max_reg_num ();
|
||
|
||
if (file)
|
||
dump_flow_info (file);
|
||
|
||
/* Return if there's nothing to do, or it is too expensive. */
|
||
if (n_basic_blocks <= 1 || is_too_expensive (_("GCSE disabled")))
|
||
return 0;
|
||
|
||
gcc_obstack_init (&gcse_obstack);
|
||
bytes_used = 0;
|
||
|
||
/* We need alias. */
|
||
init_alias_analysis ();
|
||
/* Record where pseudo-registers are set. This data is kept accurate
|
||
during each pass. ??? We could also record hard-reg information here
|
||
[since it's unchanging], however it is currently done during hash table
|
||
computation.
|
||
|
||
It may be tempting to compute MEM set information here too, but MEM sets
|
||
will be subject to code motion one day and thus we need to compute
|
||
information about memory sets when we build the hash tables. */
|
||
|
||
alloc_reg_set_mem (max_gcse_regno);
|
||
compute_sets (f);
|
||
|
||
pass = 0;
|
||
initial_bytes_used = bytes_used;
|
||
max_pass_bytes = 0;
|
||
gcse_obstack_bottom = gcse_alloc (1);
|
||
changed = 1;
|
||
while (changed && pass < MAX_GCSE_PASSES)
|
||
{
|
||
changed = 0;
|
||
if (file)
|
||
fprintf (file, "GCSE pass %d\n\n", pass + 1);
|
||
|
||
/* Initialize bytes_used to the space for the pred/succ lists,
|
||
and the reg_set_table data. */
|
||
bytes_used = initial_bytes_used;
|
||
|
||
/* Each pass may create new registers, so recalculate each time. */
|
||
max_gcse_regno = max_reg_num ();
|
||
|
||
alloc_gcse_mem (f);
|
||
|
||
/* Don't allow constant propagation to modify jumps
|
||
during this pass. */
|
||
changed = one_cprop_pass (pass + 1, 0, 0);
|
||
|
||
if (optimize_size)
|
||
changed |= one_classic_gcse_pass (pass + 1);
|
||
else
|
||
{
|
||
changed |= one_pre_gcse_pass (pass + 1);
|
||
/* We may have just created new basic blocks. Release and
|
||
recompute various things which are sized on the number of
|
||
basic blocks. */
|
||
if (changed)
|
||
{
|
||
free_modify_mem_tables ();
|
||
modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
|
||
canon_modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
|
||
}
|
||
free_reg_set_mem ();
|
||
alloc_reg_set_mem (max_reg_num ());
|
||
compute_sets (f);
|
||
run_jump_opt_after_gcse = 1;
|
||
}
|
||
|
||
if (max_pass_bytes < bytes_used)
|
||
max_pass_bytes = bytes_used;
|
||
|
||
/* Free up memory, then reallocate for code hoisting. We can
|
||
not re-use the existing allocated memory because the tables
|
||
will not have info for the insns or registers created by
|
||
partial redundancy elimination. */
|
||
free_gcse_mem ();
|
||
|
||
/* It does not make sense to run code hoisting unless we are optimizing
|
||
for code size -- it rarely makes programs faster, and can make
|
||
them bigger if we did partial redundancy elimination (when optimizing
|
||
for space, we use a classic gcse algorithm instead of partial
|
||
redundancy algorithms). */
|
||
if (optimize_size)
|
||
{
|
||
max_gcse_regno = max_reg_num ();
|
||
alloc_gcse_mem (f);
|
||
changed |= one_code_hoisting_pass ();
|
||
free_gcse_mem ();
|
||
|
||
if (max_pass_bytes < bytes_used)
|
||
max_pass_bytes = bytes_used;
|
||
}
|
||
|
||
if (file)
|
||
{
|
||
fprintf (file, "\n");
|
||
fflush (file);
|
||
}
|
||
|
||
obstack_free (&gcse_obstack, gcse_obstack_bottom);
|
||
pass++;
|
||
}
|
||
|
||
/* Do one last pass of copy propagation, including cprop into
|
||
conditional jumps. */
|
||
|
||
max_gcse_regno = max_reg_num ();
|
||
alloc_gcse_mem (f);
|
||
/* This time, go ahead and allow cprop to alter jumps. */
|
||
one_cprop_pass (pass + 1, 1, 0);
|
||
free_gcse_mem ();
|
||
|
||
if (file)
|
||
{
|
||
fprintf (file, "GCSE of %s: %d basic blocks, ",
|
||
current_function_name (), n_basic_blocks);
|
||
fprintf (file, "%d pass%s, %d bytes\n\n",
|
||
pass, pass > 1 ? "es" : "", max_pass_bytes);
|
||
}
|
||
|
||
obstack_free (&gcse_obstack, NULL);
|
||
free_reg_set_mem ();
|
||
/* We are finished with alias. */
|
||
end_alias_analysis ();
|
||
allocate_reg_info (max_reg_num (), FALSE, FALSE);
|
||
|
||
if (!optimize_size && flag_gcse_sm)
|
||
store_motion ();
|
||
|
||
/* Record where pseudo-registers are set. */
|
||
return run_jump_opt_after_gcse;
|
||
}
|
||
|
||
/* Misc. utilities. */
|
||
|
||
/* Nonzero for each mode that supports (set (reg) (reg)).
|
||
This is trivially true for integer and floating point values.
|
||
It may or may not be true for condition codes. */
|
||
static char can_copy[(int) NUM_MACHINE_MODES];
|
||
|
||
/* Compute which modes support reg/reg copy operations. */
|
||
|
||
static void
|
||
compute_can_copy (void)
|
||
{
|
||
int i;
|
||
#ifndef AVOID_CCMODE_COPIES
|
||
rtx reg, insn;
|
||
#endif
|
||
memset (can_copy, 0, NUM_MACHINE_MODES);
|
||
|
||
start_sequence ();
|
||
for (i = 0; i < NUM_MACHINE_MODES; i++)
|
||
if (GET_MODE_CLASS (i) == MODE_CC)
|
||
{
|
||
#ifdef AVOID_CCMODE_COPIES
|
||
can_copy[i] = 0;
|
||
#else
|
||
reg = gen_rtx_REG ((enum machine_mode) i, LAST_VIRTUAL_REGISTER + 1);
|
||
insn = emit_insn (gen_rtx_SET (VOIDmode, reg, reg));
|
||
if (recog (PATTERN (insn), insn, NULL) >= 0)
|
||
can_copy[i] = 1;
|
||
#endif
|
||
}
|
||
else
|
||
can_copy[i] = 1;
|
||
|
||
end_sequence ();
|
||
}
|
||
|
||
/* Returns whether the mode supports reg/reg copy operations. */
|
||
|
||
bool
|
||
can_copy_p (enum machine_mode mode)
|
||
{
|
||
static bool can_copy_init_p = false;
|
||
|
||
if (! can_copy_init_p)
|
||
{
|
||
compute_can_copy ();
|
||
can_copy_init_p = true;
|
||
}
|
||
|
||
return can_copy[mode] != 0;
|
||
}
|
||
|
||
/* Cover function to xmalloc to record bytes allocated. */
|
||
|
||
static void *
|
||
gmalloc (size_t size)
|
||
{
|
||
bytes_used += size;
|
||
return xmalloc (size);
|
||
}
|
||
|
||
/* Cover function to xcalloc to record bytes allocated. */
|
||
|
||
static void *
|
||
gcalloc (size_t nelem, size_t elsize)
|
||
{
|
||
bytes_used += nelem * elsize;
|
||
return xcalloc (nelem, elsize);
|
||
}
|
||
|
||
/* Cover function to xrealloc.
|
||
We don't record the additional size since we don't know it.
|
||
It won't affect memory usage stats much anyway. */
|
||
|
||
static void *
|
||
grealloc (void *ptr, size_t size)
|
||
{
|
||
return xrealloc (ptr, size);
|
||
}
|
||
|
||
/* Cover function to obstack_alloc. */
|
||
|
||
static void *
|
||
gcse_alloc (unsigned long size)
|
||
{
|
||
bytes_used += size;
|
||
return obstack_alloc (&gcse_obstack, size);
|
||
}
|
||
|
||
/* Allocate memory for the cuid mapping array,
|
||
and reg/memory set tracking tables.
|
||
|
||
This is called at the start of each pass. */
|
||
|
||
static void
|
||
alloc_gcse_mem (rtx f)
|
||
{
|
||
int i;
|
||
rtx insn;
|
||
|
||
/* Find the largest UID and create a mapping from UIDs to CUIDs.
|
||
CUIDs are like UIDs except they increase monotonically, have no gaps,
|
||
and only apply to real insns. */
|
||
|
||
max_uid = get_max_uid ();
|
||
uid_cuid = gcalloc (max_uid + 1, sizeof (int));
|
||
for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
|
||
{
|
||
if (INSN_P (insn))
|
||
uid_cuid[INSN_UID (insn)] = i++;
|
||
else
|
||
uid_cuid[INSN_UID (insn)] = i;
|
||
}
|
||
|
||
/* Create a table mapping cuids to insns. */
|
||
|
||
max_cuid = i;
|
||
cuid_insn = gcalloc (max_cuid + 1, sizeof (rtx));
|
||
for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
|
||
if (INSN_P (insn))
|
||
CUID_INSN (i++) = insn;
|
||
|
||
/* Allocate vars to track sets of regs. */
|
||
reg_set_bitmap = BITMAP_XMALLOC ();
|
||
|
||
/* Allocate vars to track sets of regs, memory per block. */
|
||
reg_set_in_block = sbitmap_vector_alloc (last_basic_block, max_gcse_regno);
|
||
/* Allocate array to keep a list of insns which modify memory in each
|
||
basic block. */
|
||
modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
|
||
canon_modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
|
||
modify_mem_list_set = BITMAP_XMALLOC ();
|
||
canon_modify_mem_list_set = BITMAP_XMALLOC ();
|
||
}
|
||
|
||
/* Free memory allocated by alloc_gcse_mem. */
|
||
|
||
static void
|
||
free_gcse_mem (void)
|
||
{
|
||
free (uid_cuid);
|
||
free (cuid_insn);
|
||
|
||
BITMAP_XFREE (reg_set_bitmap);
|
||
|
||
sbitmap_vector_free (reg_set_in_block);
|
||
free_modify_mem_tables ();
|
||
BITMAP_XFREE (modify_mem_list_set);
|
||
BITMAP_XFREE (canon_modify_mem_list_set);
|
||
}
|
||
|
||
/* Many of the global optimization algorithms work by solving dataflow
|
||
equations for various expressions. Initially, some local value is
|
||
computed for each expression in each block. Then, the values across the
|
||
various blocks are combined (by following flow graph edges) to arrive at
|
||
global values. Conceptually, each set of equations is independent. We
|
||
may therefore solve all the equations in parallel, solve them one at a
|
||
time, or pick any intermediate approach.
|
||
|
||
When you're going to need N two-dimensional bitmaps, each X (say, the
|
||
number of blocks) by Y (say, the number of expressions), call this
|
||
function. It's not important what X and Y represent; only that Y
|
||
correspond to the things that can be done in parallel. This function will
|
||
return an appropriate chunking factor C; you should solve C sets of
|
||
equations in parallel. By going through this function, we can easily
|
||
trade space against time; by solving fewer equations in parallel we use
|
||
less space. */
|
||
|
||
static int
|
||
get_bitmap_width (int n, int x, int y)
|
||
{
|
||
/* It's not really worth figuring out *exactly* how much memory will
|
||
be used by a particular choice. The important thing is to get
|
||
something approximately right. */
|
||
size_t max_bitmap_memory = 10 * 1024 * 1024;
|
||
|
||
/* The number of bytes we'd use for a single column of minimum
|
||
width. */
|
||
size_t column_size = n * x * sizeof (SBITMAP_ELT_TYPE);
|
||
|
||
/* Often, it's reasonable just to solve all the equations in
|
||
parallel. */
|
||
if (column_size * SBITMAP_SET_SIZE (y) <= max_bitmap_memory)
|
||
return y;
|
||
|
||
/* Otherwise, pick the largest width we can, without going over the
|
||
limit. */
|
||
return SBITMAP_ELT_BITS * ((max_bitmap_memory + column_size - 1)
|
||
/ column_size);
|
||
}
|
||
|
||
/* Compute the local properties of each recorded expression.
|
||
|
||
Local properties are those that are defined by the block, irrespective of
|
||
other blocks.
|
||
|
||
An expression is transparent in a block if its operands are not modified
|
||
in the block.
|
||
|
||
An expression is computed (locally available) in a block if it is computed
|
||
at least once and expression would contain the same value if the
|
||
computation was moved to the end of the block.
|
||
|
||
An expression is locally anticipatable in a block if it is computed at
|
||
least once and expression would contain the same value if the computation
|
||
was moved to the beginning of the block.
|
||
|
||
We call this routine for cprop, pre and code hoisting. They all compute
|
||
basically the same information and thus can easily share this code.
|
||
|
||
TRANSP, COMP, and ANTLOC are destination sbitmaps for recording local
|
||
properties. If NULL, then it is not necessary to compute or record that
|
||
particular property.
|
||
|
||
TABLE controls which hash table to look at. If it is set hash table,
|
||
additionally, TRANSP is computed as ~TRANSP, since this is really cprop's
|
||
ABSALTERED. */
|
||
|
||
static void
|
||
compute_local_properties (sbitmap *transp, sbitmap *comp, sbitmap *antloc, struct hash_table *table)
|
||
{
|
||
unsigned int i;
|
||
|
||
/* Initialize any bitmaps that were passed in. */
|
||
if (transp)
|
||
{
|
||
if (table->set_p)
|
||
sbitmap_vector_zero (transp, last_basic_block);
|
||
else
|
||
sbitmap_vector_ones (transp, last_basic_block);
|
||
}
|
||
|
||
if (comp)
|
||
sbitmap_vector_zero (comp, last_basic_block);
|
||
if (antloc)
|
||
sbitmap_vector_zero (antloc, last_basic_block);
|
||
|
||
for (i = 0; i < table->size; i++)
|
||
{
|
||
struct expr *expr;
|
||
|
||
for (expr = table->table[i]; expr != NULL; expr = expr->next_same_hash)
|
||
{
|
||
int indx = expr->bitmap_index;
|
||
struct occr *occr;
|
||
|
||
/* The expression is transparent in this block if it is not killed.
|
||
We start by assuming all are transparent [none are killed], and
|
||
then reset the bits for those that are. */
|
||
if (transp)
|
||
compute_transp (expr->expr, indx, transp, table->set_p);
|
||
|
||
/* The occurrences recorded in antic_occr are exactly those that
|
||
we want to set to nonzero in ANTLOC. */
|
||
if (antloc)
|
||
for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
|
||
{
|
||
SET_BIT (antloc[BLOCK_NUM (occr->insn)], indx);
|
||
|
||
/* While we're scanning the table, this is a good place to
|
||
initialize this. */
|
||
occr->deleted_p = 0;
|
||
}
|
||
|
||
/* The occurrences recorded in avail_occr are exactly those that
|
||
we want to set to nonzero in COMP. */
|
||
if (comp)
|
||
for (occr = expr->avail_occr; occr != NULL; occr = occr->next)
|
||
{
|
||
SET_BIT (comp[BLOCK_NUM (occr->insn)], indx);
|
||
|
||
/* While we're scanning the table, this is a good place to
|
||
initialize this. */
|
||
occr->copied_p = 0;
|
||
}
|
||
|
||
/* While we're scanning the table, this is a good place to
|
||
initialize this. */
|
||
expr->reaching_reg = 0;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Register set information.
|
||
|
||
`reg_set_table' records where each register is set or otherwise
|
||
modified. */
|
||
|
||
static struct obstack reg_set_obstack;
|
||
|
||
static void
|
||
alloc_reg_set_mem (int n_regs)
|
||
{
|
||
reg_set_table_size = n_regs + REG_SET_TABLE_SLOP;
|
||
reg_set_table = gcalloc (reg_set_table_size, sizeof (struct reg_set *));
|
||
|
||
gcc_obstack_init (®_set_obstack);
|
||
}
|
||
|
||
static void
|
||
free_reg_set_mem (void)
|
||
{
|
||
free (reg_set_table);
|
||
obstack_free (®_set_obstack, NULL);
|
||
}
|
||
|
||
/* An OLD_INSN that used to set REGNO was replaced by NEW_INSN.
|
||
Update the corresponding `reg_set_table' entry accordingly.
|
||
We assume that NEW_INSN is not already recorded in reg_set_table[regno]. */
|
||
|
||
static void
|
||
replace_one_set (int regno, rtx old_insn, rtx new_insn)
|
||
{
|
||
struct reg_set *reg_info;
|
||
if (regno >= reg_set_table_size)
|
||
return;
|
||
for (reg_info = reg_set_table[regno]; reg_info; reg_info = reg_info->next)
|
||
if (reg_info->insn == old_insn)
|
||
{
|
||
reg_info->insn = new_insn;
|
||
break;
|
||
}
|
||
}
|
||
|
||
/* Record REGNO in the reg_set table. */
|
||
|
||
static void
|
||
record_one_set (int regno, rtx insn)
|
||
{
|
||
/* Allocate a new reg_set element and link it onto the list. */
|
||
struct reg_set *new_reg_info;
|
||
|
||
/* If the table isn't big enough, enlarge it. */
|
||
if (regno >= reg_set_table_size)
|
||
{
|
||
int new_size = regno + REG_SET_TABLE_SLOP;
|
||
|
||
reg_set_table = grealloc (reg_set_table,
|
||
new_size * sizeof (struct reg_set *));
|
||
memset (reg_set_table + reg_set_table_size, 0,
|
||
(new_size - reg_set_table_size) * sizeof (struct reg_set *));
|
||
reg_set_table_size = new_size;
|
||
}
|
||
|
||
new_reg_info = obstack_alloc (®_set_obstack, sizeof (struct reg_set));
|
||
bytes_used += sizeof (struct reg_set);
|
||
new_reg_info->insn = insn;
|
||
new_reg_info->next = reg_set_table[regno];
|
||
reg_set_table[regno] = new_reg_info;
|
||
}
|
||
|
||
/* Called from compute_sets via note_stores to handle one SET or CLOBBER in
|
||
an insn. The DATA is really the instruction in which the SET is
|
||
occurring. */
|
||
|
||
static void
|
||
record_set_info (rtx dest, rtx setter ATTRIBUTE_UNUSED, void *data)
|
||
{
|
||
rtx record_set_insn = (rtx) data;
|
||
|
||
if (GET_CODE (dest) == REG && REGNO (dest) >= FIRST_PSEUDO_REGISTER)
|
||
record_one_set (REGNO (dest), record_set_insn);
|
||
}
|
||
|
||
/* Scan the function and record each set of each pseudo-register.
|
||
|
||
This is called once, at the start of the gcse pass. See the comments for
|
||
`reg_set_table' for further documentation. */
|
||
|
||
static void
|
||
compute_sets (rtx f)
|
||
{
|
||
rtx insn;
|
||
|
||
for (insn = f; insn != 0; insn = NEXT_INSN (insn))
|
||
if (INSN_P (insn))
|
||
note_stores (PATTERN (insn), record_set_info, insn);
|
||
}
|
||
|
||
/* Hash table support. */
|
||
|
||
struct reg_avail_info
|
||
{
|
||
basic_block last_bb;
|
||
int first_set;
|
||
int last_set;
|
||
};
|
||
|
||
static struct reg_avail_info *reg_avail_info;
|
||
static basic_block current_bb;
|
||
|
||
|
||
/* See whether X, the source of a set, is something we want to consider for
|
||
GCSE. */
|
||
|
||
static GTY(()) rtx test_insn;
|
||
static int
|
||
want_to_gcse_p (rtx x)
|
||
{
|
||
int num_clobbers = 0;
|
||
int icode;
|
||
|
||
switch (GET_CODE (x))
|
||
{
|
||
case REG:
|
||
case SUBREG:
|
||
case CONST_INT:
|
||
case CONST_DOUBLE:
|
||
case CONST_VECTOR:
|
||
case CALL:
|
||
case CONSTANT_P_RTX:
|
||
return 0;
|
||
|
||
default:
|
||
break;
|
||
}
|
||
|
||
/* If this is a valid operand, we are OK. If it's VOIDmode, we aren't. */
|
||
if (general_operand (x, GET_MODE (x)))
|
||
return 1;
|
||
else if (GET_MODE (x) == VOIDmode)
|
||
return 0;
|
||
|
||
/* Otherwise, check if we can make a valid insn from it. First initialize
|
||
our test insn if we haven't already. */
|
||
if (test_insn == 0)
|
||
{
|
||
test_insn
|
||
= make_insn_raw (gen_rtx_SET (VOIDmode,
|
||
gen_rtx_REG (word_mode,
|
||
FIRST_PSEUDO_REGISTER * 2),
|
||
const0_rtx));
|
||
NEXT_INSN (test_insn) = PREV_INSN (test_insn) = 0;
|
||
}
|
||
|
||
/* Now make an insn like the one we would make when GCSE'ing and see if
|
||
valid. */
|
||
PUT_MODE (SET_DEST (PATTERN (test_insn)), GET_MODE (x));
|
||
SET_SRC (PATTERN (test_insn)) = x;
|
||
return ((icode = recog (PATTERN (test_insn), test_insn, &num_clobbers)) >= 0
|
||
&& (num_clobbers == 0 || ! added_clobbers_hard_reg_p (icode)));
|
||
}
|
||
|
||
/* Return nonzero if the operands of expression X are unchanged from the
|
||
start of INSN's basic block up to but not including INSN (if AVAIL_P == 0),
|
||
or from INSN to the end of INSN's basic block (if AVAIL_P != 0). */
|
||
|
||
static int
|
||
oprs_unchanged_p (rtx x, rtx insn, int avail_p)
|
||
{
|
||
int i, j;
|
||
enum rtx_code code;
|
||
const char *fmt;
|
||
|
||
if (x == 0)
|
||
return 1;
|
||
|
||
code = GET_CODE (x);
|
||
switch (code)
|
||
{
|
||
case REG:
|
||
{
|
||
struct reg_avail_info *info = ®_avail_info[REGNO (x)];
|
||
|
||
if (info->last_bb != current_bb)
|
||
return 1;
|
||
if (avail_p)
|
||
return info->last_set < INSN_CUID (insn);
|
||
else
|
||
return info->first_set >= INSN_CUID (insn);
|
||
}
|
||
|
||
case MEM:
|
||
if (load_killed_in_block_p (current_bb, INSN_CUID (insn),
|
||
x, avail_p))
|
||
return 0;
|
||
else
|
||
return oprs_unchanged_p (XEXP (x, 0), insn, avail_p);
|
||
|
||
case PRE_DEC:
|
||
case PRE_INC:
|
||
case POST_DEC:
|
||
case POST_INC:
|
||
case PRE_MODIFY:
|
||
case POST_MODIFY:
|
||
return 0;
|
||
|
||
case PC:
|
||
case CC0: /*FIXME*/
|
||
case CONST:
|
||
case CONST_INT:
|
||
case CONST_DOUBLE:
|
||
case CONST_VECTOR:
|
||
case SYMBOL_REF:
|
||
case LABEL_REF:
|
||
case ADDR_VEC:
|
||
case ADDR_DIFF_VEC:
|
||
return 1;
|
||
|
||
default:
|
||
break;
|
||
}
|
||
|
||
for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
|
||
{
|
||
if (fmt[i] == 'e')
|
||
{
|
||
/* If we are about to do the last recursive call needed at this
|
||
level, change it into iteration. This function is called enough
|
||
to be worth it. */
|
||
if (i == 0)
|
||
return oprs_unchanged_p (XEXP (x, i), insn, avail_p);
|
||
|
||
else if (! oprs_unchanged_p (XEXP (x, i), insn, avail_p))
|
||
return 0;
|
||
}
|
||
else if (fmt[i] == 'E')
|
||
for (j = 0; j < XVECLEN (x, i); j++)
|
||
if (! oprs_unchanged_p (XVECEXP (x, i, j), insn, avail_p))
|
||
return 0;
|
||
}
|
||
|
||
return 1;
|
||
}
|
||
|
||
/* Used for communication between mems_conflict_for_gcse_p and
|
||
load_killed_in_block_p. Nonzero if mems_conflict_for_gcse_p finds a
|
||
conflict between two memory references. */
|
||
static int gcse_mems_conflict_p;
|
||
|
||
/* Used for communication between mems_conflict_for_gcse_p and
|
||
load_killed_in_block_p. A memory reference for a load instruction,
|
||
mems_conflict_for_gcse_p will see if a memory store conflicts with
|
||
this memory load. */
|
||
static rtx gcse_mem_operand;
|
||
|
||
/* DEST is the output of an instruction. If it is a memory reference, and
|
||
possibly conflicts with the load found in gcse_mem_operand, then set
|
||
gcse_mems_conflict_p to a nonzero value. */
|
||
|
||
static void
|
||
mems_conflict_for_gcse_p (rtx dest, rtx setter ATTRIBUTE_UNUSED,
|
||
void *data ATTRIBUTE_UNUSED)
|
||
{
|
||
while (GET_CODE (dest) == SUBREG
|
||
|| GET_CODE (dest) == ZERO_EXTRACT
|
||
|| GET_CODE (dest) == SIGN_EXTRACT
|
||
|| GET_CODE (dest) == STRICT_LOW_PART)
|
||
dest = XEXP (dest, 0);
|
||
|
||
/* If DEST is not a MEM, then it will not conflict with the load. Note
|
||
that function calls are assumed to clobber memory, but are handled
|
||
elsewhere. */
|
||
if (GET_CODE (dest) != MEM)
|
||
return;
|
||
|
||
/* If we are setting a MEM in our list of specially recognized MEMs,
|
||
don't mark as killed this time. */
|
||
|
||
if (expr_equiv_p (dest, gcse_mem_operand) && pre_ldst_mems != NULL)
|
||
{
|
||
if (!find_rtx_in_ldst (dest))
|
||
gcse_mems_conflict_p = 1;
|
||
return;
|
||
}
|
||
|
||
if (true_dependence (dest, GET_MODE (dest), gcse_mem_operand,
|
||
rtx_addr_varies_p))
|
||
gcse_mems_conflict_p = 1;
|
||
}
|
||
|
||
/* Return nonzero if the expression in X (a memory reference) is killed
|
||
in block BB before or after the insn with the CUID in UID_LIMIT.
|
||
AVAIL_P is nonzero for kills after UID_LIMIT, and zero for kills
|
||
before UID_LIMIT.
|
||
|
||
To check the entire block, set UID_LIMIT to max_uid + 1 and
|
||
AVAIL_P to 0. */
|
||
|
||
static int
|
||
load_killed_in_block_p (basic_block bb, int uid_limit, rtx x, int avail_p)
|
||
{
|
||
rtx list_entry = modify_mem_list[bb->index];
|
||
while (list_entry)
|
||
{
|
||
rtx setter;
|
||
/* Ignore entries in the list that do not apply. */
|
||
if ((avail_p
|
||
&& INSN_CUID (XEXP (list_entry, 0)) < uid_limit)
|
||
|| (! avail_p
|
||
&& INSN_CUID (XEXP (list_entry, 0)) > uid_limit))
|
||
{
|
||
list_entry = XEXP (list_entry, 1);
|
||
continue;
|
||
}
|
||
|
||
setter = XEXP (list_entry, 0);
|
||
|
||
/* If SETTER is a call everything is clobbered. Note that calls
|
||
to pure functions are never put on the list, so we need not
|
||
worry about them. */
|
||
if (GET_CODE (setter) == CALL_INSN)
|
||
return 1;
|
||
|
||
/* SETTER must be an INSN of some kind that sets memory. Call
|
||
note_stores to examine each hunk of memory that is modified.
|
||
|
||
The note_stores interface is pretty limited, so we have to
|
||
communicate via global variables. Yuk. */
|
||
gcse_mem_operand = x;
|
||
gcse_mems_conflict_p = 0;
|
||
note_stores (PATTERN (setter), mems_conflict_for_gcse_p, NULL);
|
||
if (gcse_mems_conflict_p)
|
||
return 1;
|
||
list_entry = XEXP (list_entry, 1);
|
||
}
|
||
return 0;
|
||
}
|
||
|
||
/* Return nonzero if the operands of expression X are unchanged from
|
||
the start of INSN's basic block up to but not including INSN. */
|
||
|
||
static int
|
||
oprs_anticipatable_p (rtx x, rtx insn)
|
||
{
|
||
return oprs_unchanged_p (x, insn, 0);
|
||
}
|
||
|
||
/* Return nonzero if the operands of expression X are unchanged from
|
||
INSN to the end of INSN's basic block. */
|
||
|
||
static int
|
||
oprs_available_p (rtx x, rtx insn)
|
||
{
|
||
return oprs_unchanged_p (x, insn, 1);
|
||
}
|
||
|
||
/* Hash expression X.
|
||
|
||
MODE is only used if X is a CONST_INT. DO_NOT_RECORD_P is a boolean
|
||
indicating if a volatile operand is found or if the expression contains
|
||
something we don't want to insert in the table. HASH_TABLE_SIZE is
|
||
the current size of the hash table to be probed.
|
||
|
||
??? One might want to merge this with canon_hash. Later. */
|
||
|
||
static unsigned int
|
||
hash_expr (rtx x, enum machine_mode mode, int *do_not_record_p,
|
||
int hash_table_size)
|
||
{
|
||
unsigned int hash;
|
||
|
||
*do_not_record_p = 0;
|
||
|
||
hash = hash_expr_1 (x, mode, do_not_record_p);
|
||
return hash % hash_table_size;
|
||
}
|
||
|
||
/* Hash a string. Just add its bytes up. */
|
||
|
||
static inline unsigned
|
||
hash_string_1 (const char *ps)
|
||
{
|
||
unsigned hash = 0;
|
||
const unsigned char *p = (const unsigned char *) ps;
|
||
|
||
if (p)
|
||
while (*p)
|
||
hash += *p++;
|
||
|
||
return hash;
|
||
}
|
||
|
||
/* Subroutine of hash_expr to do the actual work. */
|
||
|
||
static unsigned int
|
||
hash_expr_1 (rtx x, enum machine_mode mode, int *do_not_record_p)
|
||
{
|
||
int i, j;
|
||
unsigned hash = 0;
|
||
enum rtx_code code;
|
||
const char *fmt;
|
||
|
||
/* Used to turn recursion into iteration. We can't rely on GCC's
|
||
tail-recursion elimination since we need to keep accumulating values
|
||
in HASH. */
|
||
|
||
if (x == 0)
|
||
return hash;
|
||
|
||
repeat:
|
||
code = GET_CODE (x);
|
||
switch (code)
|
||
{
|
||
case REG:
|
||
hash += ((unsigned int) REG << 7) + REGNO (x);
|
||
return hash;
|
||
|
||
case CONST_INT:
|
||
hash += (((unsigned int) CONST_INT << 7) + (unsigned int) mode
|
||
+ (unsigned int) INTVAL (x));
|
||
return hash;
|
||
|
||
case CONST_DOUBLE:
|
||
/* This is like the general case, except that it only counts
|
||
the integers representing the constant. */
|
||
hash += (unsigned int) code + (unsigned int) GET_MODE (x);
|
||
if (GET_MODE (x) != VOIDmode)
|
||
for (i = 2; i < GET_RTX_LENGTH (CONST_DOUBLE); i++)
|
||
hash += (unsigned int) XWINT (x, i);
|
||
else
|
||
hash += ((unsigned int) CONST_DOUBLE_LOW (x)
|
||
+ (unsigned int) CONST_DOUBLE_HIGH (x));
|
||
return hash;
|
||
|
||
case CONST_VECTOR:
|
||
{
|
||
int units;
|
||
rtx elt;
|
||
|
||
units = CONST_VECTOR_NUNITS (x);
|
||
|
||
for (i = 0; i < units; ++i)
|
||
{
|
||
elt = CONST_VECTOR_ELT (x, i);
|
||
hash += hash_expr_1 (elt, GET_MODE (elt), do_not_record_p);
|
||
}
|
||
|
||
return hash;
|
||
}
|
||
|
||
/* Assume there is only one rtx object for any given label. */
|
||
case LABEL_REF:
|
||
/* We don't hash on the address of the CODE_LABEL to avoid bootstrap
|
||
differences and differences between each stage's debugging dumps. */
|
||
hash += (((unsigned int) LABEL_REF << 7)
|
||
+ CODE_LABEL_NUMBER (XEXP (x, 0)));
|
||
return hash;
|
||
|
||
case SYMBOL_REF:
|
||
{
|
||
/* Don't hash on the symbol's address to avoid bootstrap differences.
|
||
Different hash values may cause expressions to be recorded in
|
||
different orders and thus different registers to be used in the
|
||
final assembler. This also avoids differences in the dump files
|
||
between various stages. */
|
||
unsigned int h = 0;
|
||
const unsigned char *p = (const unsigned char *) XSTR (x, 0);
|
||
|
||
while (*p)
|
||
h += (h << 7) + *p++; /* ??? revisit */
|
||
|
||
hash += ((unsigned int) SYMBOL_REF << 7) + h;
|
||
return hash;
|
||
}
|
||
|
||
case MEM:
|
||
if (MEM_VOLATILE_P (x))
|
||
{
|
||
*do_not_record_p = 1;
|
||
return 0;
|
||
}
|
||
|
||
hash += (unsigned int) MEM;
|
||
/* We used alias set for hashing, but this is not good, since the alias
|
||
set may differ in -fprofile-arcs and -fbranch-probabilities compilation
|
||
causing the profiles to fail to match. */
|
||
x = XEXP (x, 0);
|
||
goto repeat;
|
||
|
||
case PRE_DEC:
|
||
case PRE_INC:
|
||
case POST_DEC:
|
||
case POST_INC:
|
||
case PC:
|
||
case CC0:
|
||
case CALL:
|
||
case UNSPEC_VOLATILE:
|
||
*do_not_record_p = 1;
|
||
return 0;
|
||
|
||
case ASM_OPERANDS:
|
||
if (MEM_VOLATILE_P (x))
|
||
{
|
||
*do_not_record_p = 1;
|
||
return 0;
|
||
}
|
||
else
|
||
{
|
||
/* We don't want to take the filename and line into account. */
|
||
hash += (unsigned) code + (unsigned) GET_MODE (x)
|
||
+ hash_string_1 (ASM_OPERANDS_TEMPLATE (x))
|
||
+ hash_string_1 (ASM_OPERANDS_OUTPUT_CONSTRAINT (x))
|
||
+ (unsigned) ASM_OPERANDS_OUTPUT_IDX (x);
|
||
|
||
if (ASM_OPERANDS_INPUT_LENGTH (x))
|
||
{
|
||
for (i = 1; i < ASM_OPERANDS_INPUT_LENGTH (x); i++)
|
||
{
|
||
hash += (hash_expr_1 (ASM_OPERANDS_INPUT (x, i),
|
||
GET_MODE (ASM_OPERANDS_INPUT (x, i)),
|
||
do_not_record_p)
|
||
+ hash_string_1 (ASM_OPERANDS_INPUT_CONSTRAINT
|
||
(x, i)));
|
||
}
|
||
|
||
hash += hash_string_1 (ASM_OPERANDS_INPUT_CONSTRAINT (x, 0));
|
||
x = ASM_OPERANDS_INPUT (x, 0);
|
||
mode = GET_MODE (x);
|
||
goto repeat;
|
||
}
|
||
return hash;
|
||
}
|
||
|
||
default:
|
||
break;
|
||
}
|
||
|
||
hash += (unsigned) code + (unsigned) GET_MODE (x);
|
||
for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
|
||
{
|
||
if (fmt[i] == 'e')
|
||
{
|
||
/* If we are about to do the last recursive call
|
||
needed at this level, change it into iteration.
|
||
This function is called enough to be worth it. */
|
||
if (i == 0)
|
||
{
|
||
x = XEXP (x, i);
|
||
goto repeat;
|
||
}
|
||
|
||
hash += hash_expr_1 (XEXP (x, i), 0, do_not_record_p);
|
||
if (*do_not_record_p)
|
||
return 0;
|
||
}
|
||
|
||
else if (fmt[i] == 'E')
|
||
for (j = 0; j < XVECLEN (x, i); j++)
|
||
{
|
||
hash += hash_expr_1 (XVECEXP (x, i, j), 0, do_not_record_p);
|
||
if (*do_not_record_p)
|
||
return 0;
|
||
}
|
||
|
||
else if (fmt[i] == 's')
|
||
hash += hash_string_1 (XSTR (x, i));
|
||
else if (fmt[i] == 'i')
|
||
hash += (unsigned int) XINT (x, i);
|
||
else
|
||
abort ();
|
||
}
|
||
|
||
return hash;
|
||
}
|
||
|
||
/* Hash a set of register REGNO.
|
||
|
||
Sets are hashed on the register that is set. This simplifies the PRE copy
|
||
propagation code.
|
||
|
||
??? May need to make things more elaborate. Later, as necessary. */
|
||
|
||
static unsigned int
|
||
hash_set (int regno, int hash_table_size)
|
||
{
|
||
unsigned int hash;
|
||
|
||
hash = regno;
|
||
return hash % hash_table_size;
|
||
}
|
||
|
||
/* Return nonzero if exp1 is equivalent to exp2.
|
||
??? Borrowed from cse.c. Might want to remerge with cse.c. Later. */
|
||
|
||
static int
|
||
expr_equiv_p (rtx x, rtx y)
|
||
{
|
||
int i, j;
|
||
enum rtx_code code;
|
||
const char *fmt;
|
||
|
||
if (x == y)
|
||
return 1;
|
||
|
||
if (x == 0 || y == 0)
|
||
return 0;
|
||
|
||
code = GET_CODE (x);
|
||
if (code != GET_CODE (y))
|
||
return 0;
|
||
|
||
/* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
|
||
if (GET_MODE (x) != GET_MODE (y))
|
||
return 0;
|
||
|
||
switch (code)
|
||
{
|
||
case PC:
|
||
case CC0:
|
||
case CONST_INT:
|
||
return 0;
|
||
|
||
case LABEL_REF:
|
||
return XEXP (x, 0) == XEXP (y, 0);
|
||
|
||
case SYMBOL_REF:
|
||
return XSTR (x, 0) == XSTR (y, 0);
|
||
|
||
case REG:
|
||
return REGNO (x) == REGNO (y);
|
||
|
||
case MEM:
|
||
/* Can't merge two expressions in different alias sets, since we can
|
||
decide that the expression is transparent in a block when it isn't,
|
||
due to it being set with the different alias set. */
|
||
if (MEM_ALIAS_SET (x) != MEM_ALIAS_SET (y))
|
||
return 0;
|
||
|
||
/* A volatile mem should not be considered equivalent to any other. */
|
||
if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
|
||
return 0;
|
||
break;
|
||
|
||
/* For commutative operations, check both orders. */
|
||
case PLUS:
|
||
case MULT:
|
||
case AND:
|
||
case IOR:
|
||
case XOR:
|
||
case NE:
|
||
case EQ:
|
||
return ((expr_equiv_p (XEXP (x, 0), XEXP (y, 0))
|
||
&& expr_equiv_p (XEXP (x, 1), XEXP (y, 1)))
|
||
|| (expr_equiv_p (XEXP (x, 0), XEXP (y, 1))
|
||
&& expr_equiv_p (XEXP (x, 1), XEXP (y, 0))));
|
||
|
||
case ASM_OPERANDS:
|
||
/* We don't use the generic code below because we want to
|
||
disregard filename and line numbers. */
|
||
|
||
/* A volatile asm isn't equivalent to any other. */
|
||
if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
|
||
return 0;
|
||
|
||
if (GET_MODE (x) != GET_MODE (y)
|
||
|| strcmp (ASM_OPERANDS_TEMPLATE (x), ASM_OPERANDS_TEMPLATE (y))
|
||
|| strcmp (ASM_OPERANDS_OUTPUT_CONSTRAINT (x),
|
||
ASM_OPERANDS_OUTPUT_CONSTRAINT (y))
|
||
|| ASM_OPERANDS_OUTPUT_IDX (x) != ASM_OPERANDS_OUTPUT_IDX (y)
|
||
|| ASM_OPERANDS_INPUT_LENGTH (x) != ASM_OPERANDS_INPUT_LENGTH (y))
|
||
return 0;
|
||
|
||
if (ASM_OPERANDS_INPUT_LENGTH (x))
|
||
{
|
||
for (i = ASM_OPERANDS_INPUT_LENGTH (x) - 1; i >= 0; i--)
|
||
if (! expr_equiv_p (ASM_OPERANDS_INPUT (x, i),
|
||
ASM_OPERANDS_INPUT (y, i))
|
||
|| strcmp (ASM_OPERANDS_INPUT_CONSTRAINT (x, i),
|
||
ASM_OPERANDS_INPUT_CONSTRAINT (y, i)))
|
||
return 0;
|
||
}
|
||
|
||
return 1;
|
||
|
||
default:
|
||
break;
|
||
}
|
||
|
||
/* Compare the elements. If any pair of corresponding elements
|
||
fail to match, return 0 for the whole thing. */
|
||
|
||
fmt = GET_RTX_FORMAT (code);
|
||
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
|
||
{
|
||
switch (fmt[i])
|
||
{
|
||
case 'e':
|
||
if (! expr_equiv_p (XEXP (x, i), XEXP (y, i)))
|
||
return 0;
|
||
break;
|
||
|
||
case 'E':
|
||
if (XVECLEN (x, i) != XVECLEN (y, i))
|
||
return 0;
|
||
for (j = 0; j < XVECLEN (x, i); j++)
|
||
if (! expr_equiv_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
|
||
return 0;
|
||
break;
|
||
|
||
case 's':
|
||
if (strcmp (XSTR (x, i), XSTR (y, i)))
|
||
return 0;
|
||
break;
|
||
|
||
case 'i':
|
||
if (XINT (x, i) != XINT (y, i))
|
||
return 0;
|
||
break;
|
||
|
||
case 'w':
|
||
if (XWINT (x, i) != XWINT (y, i))
|
||
return 0;
|
||
break;
|
||
|
||
case '0':
|
||
break;
|
||
|
||
default:
|
||
abort ();
|
||
}
|
||
}
|
||
|
||
return 1;
|
||
}
|
||
|
||
/* Insert expression X in INSN in the hash TABLE.
|
||
If it is already present, record it as the last occurrence in INSN's
|
||
basic block.
|
||
|
||
MODE is the mode of the value X is being stored into.
|
||
It is only used if X is a CONST_INT.
|
||
|
||
ANTIC_P is nonzero if X is an anticipatable expression.
|
||
AVAIL_P is nonzero if X is an available expression. */
|
||
|
||
static void
|
||
insert_expr_in_table (rtx x, enum machine_mode mode, rtx insn, int antic_p,
|
||
int avail_p, struct hash_table *table)
|
||
{
|
||
int found, do_not_record_p;
|
||
unsigned int hash;
|
||
struct expr *cur_expr, *last_expr = NULL;
|
||
struct occr *antic_occr, *avail_occr;
|
||
struct occr *last_occr = NULL;
|
||
|
||
hash = hash_expr (x, mode, &do_not_record_p, table->size);
|
||
|
||
/* Do not insert expression in table if it contains volatile operands,
|
||
or if hash_expr determines the expression is something we don't want
|
||
to or can't handle. */
|
||
if (do_not_record_p)
|
||
return;
|
||
|
||
cur_expr = table->table[hash];
|
||
found = 0;
|
||
|
||
while (cur_expr && 0 == (found = expr_equiv_p (cur_expr->expr, x)))
|
||
{
|
||
/* If the expression isn't found, save a pointer to the end of
|
||
the list. */
|
||
last_expr = cur_expr;
|
||
cur_expr = cur_expr->next_same_hash;
|
||
}
|
||
|
||
if (! found)
|
||
{
|
||
cur_expr = gcse_alloc (sizeof (struct expr));
|
||
bytes_used += sizeof (struct expr);
|
||
if (table->table[hash] == NULL)
|
||
/* This is the first pattern that hashed to this index. */
|
||
table->table[hash] = cur_expr;
|
||
else
|
||
/* Add EXPR to end of this hash chain. */
|
||
last_expr->next_same_hash = cur_expr;
|
||
|
||
/* Set the fields of the expr element. */
|
||
cur_expr->expr = x;
|
||
cur_expr->bitmap_index = table->n_elems++;
|
||
cur_expr->next_same_hash = NULL;
|
||
cur_expr->antic_occr = NULL;
|
||
cur_expr->avail_occr = NULL;
|
||
}
|
||
|
||
/* Now record the occurrence(s). */
|
||
if (antic_p)
|
||
{
|
||
antic_occr = cur_expr->antic_occr;
|
||
|
||
/* Search for another occurrence in the same basic block. */
|
||
while (antic_occr && BLOCK_NUM (antic_occr->insn) != BLOCK_NUM (insn))
|
||
{
|
||
/* If an occurrence isn't found, save a pointer to the end of
|
||
the list. */
|
||
last_occr = antic_occr;
|
||
antic_occr = antic_occr->next;
|
||
}
|
||
|
||
if (antic_occr)
|
||
/* Found another instance of the expression in the same basic block.
|
||
Prefer the currently recorded one. We want the first one in the
|
||
block and the block is scanned from start to end. */
|
||
; /* nothing to do */
|
||
else
|
||
{
|
||
/* First occurrence of this expression in this basic block. */
|
||
antic_occr = gcse_alloc (sizeof (struct occr));
|
||
bytes_used += sizeof (struct occr);
|
||
/* First occurrence of this expression in any block? */
|
||
if (cur_expr->antic_occr == NULL)
|
||
cur_expr->antic_occr = antic_occr;
|
||
else
|
||
last_occr->next = antic_occr;
|
||
|
||
antic_occr->insn = insn;
|
||
antic_occr->next = NULL;
|
||
}
|
||
}
|
||
|
||
if (avail_p)
|
||
{
|
||
avail_occr = cur_expr->avail_occr;
|
||
|
||
/* Search for another occurrence in the same basic block. */
|
||
while (avail_occr && BLOCK_NUM (avail_occr->insn) != BLOCK_NUM (insn))
|
||
{
|
||
/* If an occurrence isn't found, save a pointer to the end of
|
||
the list. */
|
||
last_occr = avail_occr;
|
||
avail_occr = avail_occr->next;
|
||
}
|
||
|
||
if (avail_occr)
|
||
/* Found another instance of the expression in the same basic block.
|
||
Prefer this occurrence to the currently recorded one. We want
|
||
the last one in the block and the block is scanned from start
|
||
to end. */
|
||
avail_occr->insn = insn;
|
||
else
|
||
{
|
||
/* First occurrence of this expression in this basic block. */
|
||
avail_occr = gcse_alloc (sizeof (struct occr));
|
||
bytes_used += sizeof (struct occr);
|
||
|
||
/* First occurrence of this expression in any block? */
|
||
if (cur_expr->avail_occr == NULL)
|
||
cur_expr->avail_occr = avail_occr;
|
||
else
|
||
last_occr->next = avail_occr;
|
||
|
||
avail_occr->insn = insn;
|
||
avail_occr->next = NULL;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Insert pattern X in INSN in the hash table.
|
||
X is a SET of a reg to either another reg or a constant.
|
||
If it is already present, record it as the last occurrence in INSN's
|
||
basic block. */
|
||
|
||
static void
|
||
insert_set_in_table (rtx x, rtx insn, struct hash_table *table)
|
||
{
|
||
int found;
|
||
unsigned int hash;
|
||
struct expr *cur_expr, *last_expr = NULL;
|
||
struct occr *cur_occr, *last_occr = NULL;
|
||
|
||
if (GET_CODE (x) != SET
|
||
|| GET_CODE (SET_DEST (x)) != REG)
|
||
abort ();
|
||
|
||
hash = hash_set (REGNO (SET_DEST (x)), table->size);
|
||
|
||
cur_expr = table->table[hash];
|
||
found = 0;
|
||
|
||
while (cur_expr && 0 == (found = expr_equiv_p (cur_expr->expr, x)))
|
||
{
|
||
/* If the expression isn't found, save a pointer to the end of
|
||
the list. */
|
||
last_expr = cur_expr;
|
||
cur_expr = cur_expr->next_same_hash;
|
||
}
|
||
|
||
if (! found)
|
||
{
|
||
cur_expr = gcse_alloc (sizeof (struct expr));
|
||
bytes_used += sizeof (struct expr);
|
||
if (table->table[hash] == NULL)
|
||
/* This is the first pattern that hashed to this index. */
|
||
table->table[hash] = cur_expr;
|
||
else
|
||
/* Add EXPR to end of this hash chain. */
|
||
last_expr->next_same_hash = cur_expr;
|
||
|
||
/* Set the fields of the expr element.
|
||
We must copy X because it can be modified when copy propagation is
|
||
performed on its operands. */
|
||
cur_expr->expr = copy_rtx (x);
|
||
cur_expr->bitmap_index = table->n_elems++;
|
||
cur_expr->next_same_hash = NULL;
|
||
cur_expr->antic_occr = NULL;
|
||
cur_expr->avail_occr = NULL;
|
||
}
|
||
|
||
/* Now record the occurrence. */
|
||
cur_occr = cur_expr->avail_occr;
|
||
|
||
/* Search for another occurrence in the same basic block. */
|
||
while (cur_occr && BLOCK_NUM (cur_occr->insn) != BLOCK_NUM (insn))
|
||
{
|
||
/* If an occurrence isn't found, save a pointer to the end of
|
||
the list. */
|
||
last_occr = cur_occr;
|
||
cur_occr = cur_occr->next;
|
||
}
|
||
|
||
if (cur_occr)
|
||
/* Found another instance of the expression in the same basic block.
|
||
Prefer this occurrence to the currently recorded one. We want the
|
||
last one in the block and the block is scanned from start to end. */
|
||
cur_occr->insn = insn;
|
||
else
|
||
{
|
||
/* First occurrence of this expression in this basic block. */
|
||
cur_occr = gcse_alloc (sizeof (struct occr));
|
||
bytes_used += sizeof (struct occr);
|
||
|
||
/* First occurrence of this expression in any block? */
|
||
if (cur_expr->avail_occr == NULL)
|
||
cur_expr->avail_occr = cur_occr;
|
||
else
|
||
last_occr->next = cur_occr;
|
||
|
||
cur_occr->insn = insn;
|
||
cur_occr->next = NULL;
|
||
}
|
||
}
|
||
|
||
/* Determine whether the rtx X should be treated as a constant for
|
||
the purposes of GCSE's constant propagation. */
|
||
|
||
static bool
|
||
gcse_constant_p (rtx x)
|
||
{
|
||
/* Consider a COMPARE of two integers constant. */
|
||
if (GET_CODE (x) == COMPARE
|
||
&& GET_CODE (XEXP (x, 0)) == CONST_INT
|
||
&& GET_CODE (XEXP (x, 1)) == CONST_INT)
|
||
return true;
|
||
|
||
|
||
/* Consider a COMPARE of the same registers is a constant
|
||
if they are not floating point registers. */
|
||
if (GET_CODE(x) == COMPARE
|
||
&& GET_CODE (XEXP (x, 0)) == REG
|
||
&& GET_CODE (XEXP (x, 1)) == REG
|
||
&& REGNO (XEXP (x, 0)) == REGNO (XEXP (x, 1))
|
||
&& ! FLOAT_MODE_P (GET_MODE (XEXP (x, 0)))
|
||
&& ! FLOAT_MODE_P (GET_MODE (XEXP (x, 1))))
|
||
return true;
|
||
|
||
if (GET_CODE (x) == CONSTANT_P_RTX)
|
||
return false;
|
||
|
||
return CONSTANT_P (x);
|
||
}
|
||
|
||
/* Scan pattern PAT of INSN and add an entry to the hash TABLE (set or
|
||
expression one). */
|
||
|
||
static void
|
||
hash_scan_set (rtx pat, rtx insn, struct hash_table *table)
|
||
{
|
||
rtx src = SET_SRC (pat);
|
||
rtx dest = SET_DEST (pat);
|
||
rtx note;
|
||
|
||
if (GET_CODE (src) == CALL)
|
||
hash_scan_call (src, insn, table);
|
||
|
||
else if (GET_CODE (dest) == REG)
|
||
{
|
||
unsigned int regno = REGNO (dest);
|
||
rtx tmp;
|
||
|
||
/* If this is a single set and we are doing constant propagation,
|
||
see if a REG_NOTE shows this equivalent to a constant. */
|
||
if (table->set_p && (note = find_reg_equal_equiv_note (insn)) != 0
|
||
&& gcse_constant_p (XEXP (note, 0)))
|
||
src = XEXP (note, 0), pat = gen_rtx_SET (VOIDmode, dest, src);
|
||
|
||
/* Only record sets of pseudo-regs in the hash table. */
|
||
if (! table->set_p
|
||
&& regno >= FIRST_PSEUDO_REGISTER
|
||
/* Don't GCSE something if we can't do a reg/reg copy. */
|
||
&& can_copy_p (GET_MODE (dest))
|
||
/* GCSE commonly inserts instruction after the insn. We can't
|
||
do that easily for EH_REGION notes so disable GCSE on these
|
||
for now. */
|
||
&& !find_reg_note (insn, REG_EH_REGION, NULL_RTX)
|
||
/* Is SET_SRC something we want to gcse? */
|
||
&& want_to_gcse_p (src)
|
||
/* Don't CSE a nop. */
|
||
&& ! set_noop_p (pat)
|
||
/* Don't GCSE if it has attached REG_EQUIV note.
|
||
At this point this only function parameters should have
|
||
REG_EQUIV notes and if the argument slot is used somewhere
|
||
explicitly, it means address of parameter has been taken,
|
||
so we should not extend the lifetime of the pseudo. */
|
||
&& ((note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) == 0
|
||
|| GET_CODE (XEXP (note, 0)) != MEM))
|
||
{
|
||
/* An expression is not anticipatable if its operands are
|
||
modified before this insn or if this is not the only SET in
|
||
this insn. */
|
||
int antic_p = oprs_anticipatable_p (src, insn) && single_set (insn);
|
||
/* An expression is not available if its operands are
|
||
subsequently modified, including this insn. It's also not
|
||
available if this is a branch, because we can't insert
|
||
a set after the branch. */
|
||
int avail_p = (oprs_available_p (src, insn)
|
||
&& ! JUMP_P (insn));
|
||
|
||
insert_expr_in_table (src, GET_MODE (dest), insn, antic_p, avail_p, table);
|
||
}
|
||
|
||
/* Record sets for constant/copy propagation. */
|
||
else if (table->set_p
|
||
&& regno >= FIRST_PSEUDO_REGISTER
|
||
&& ((GET_CODE (src) == REG
|
||
&& REGNO (src) >= FIRST_PSEUDO_REGISTER
|
||
&& can_copy_p (GET_MODE (dest))
|
||
&& REGNO (src) != regno)
|
||
|| gcse_constant_p (src))
|
||
/* A copy is not available if its src or dest is subsequently
|
||
modified. Here we want to search from INSN+1 on, but
|
||
oprs_available_p searches from INSN on. */
|
||
&& (insn == BB_END (BLOCK_FOR_INSN (insn))
|
||
|| ((tmp = next_nonnote_insn (insn)) != NULL_RTX
|
||
&& oprs_available_p (pat, tmp))))
|
||
insert_set_in_table (pat, insn, table);
|
||
}
|
||
/* In case of store we want to consider the memory value as available in
|
||
the REG stored in that memory. This makes it possible to remove
|
||
redundant loads from due to stores to the same location. */
|
||
else if (flag_gcse_las && GET_CODE (src) == REG && GET_CODE (dest) == MEM)
|
||
{
|
||
unsigned int regno = REGNO (src);
|
||
|
||
/* Do not do this for constant/copy propagation. */
|
||
if (! table->set_p
|
||
/* Only record sets of pseudo-regs in the hash table. */
|
||
&& regno >= FIRST_PSEUDO_REGISTER
|
||
/* Don't GCSE something if we can't do a reg/reg copy. */
|
||
&& can_copy_p (GET_MODE (src))
|
||
/* GCSE commonly inserts instruction after the insn. We can't
|
||
do that easily for EH_REGION notes so disable GCSE on these
|
||
for now. */
|
||
&& ! find_reg_note (insn, REG_EH_REGION, NULL_RTX)
|
||
/* Is SET_DEST something we want to gcse? */
|
||
&& want_to_gcse_p (dest)
|
||
/* Don't CSE a nop. */
|
||
&& ! set_noop_p (pat)
|
||
/* Don't GCSE if it has attached REG_EQUIV note.
|
||
At this point this only function parameters should have
|
||
REG_EQUIV notes and if the argument slot is used somewhere
|
||
explicitly, it means address of parameter has been taken,
|
||
so we should not extend the lifetime of the pseudo. */
|
||
&& ((note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) == 0
|
||
|| GET_CODE (XEXP (note, 0)) != MEM))
|
||
{
|
||
/* Stores are never anticipatable. */
|
||
int antic_p = 0;
|
||
/* An expression is not available if its operands are
|
||
subsequently modified, including this insn. It's also not
|
||
available if this is a branch, because we can't insert
|
||
a set after the branch. */
|
||
int avail_p = oprs_available_p (dest, insn)
|
||
&& ! JUMP_P (insn);
|
||
|
||
/* Record the memory expression (DEST) in the hash table. */
|
||
insert_expr_in_table (dest, GET_MODE (dest), insn,
|
||
antic_p, avail_p, table);
|
||
}
|
||
}
|
||
}
|
||
|
||
static void
|
||
hash_scan_clobber (rtx x ATTRIBUTE_UNUSED, rtx insn ATTRIBUTE_UNUSED,
|
||
struct hash_table *table ATTRIBUTE_UNUSED)
|
||
{
|
||
/* Currently nothing to do. */
|
||
}
|
||
|
||
static void
|
||
hash_scan_call (rtx x ATTRIBUTE_UNUSED, rtx insn ATTRIBUTE_UNUSED,
|
||
struct hash_table *table ATTRIBUTE_UNUSED)
|
||
{
|
||
/* Currently nothing to do. */
|
||
}
|
||
|
||
/* Process INSN and add hash table entries as appropriate.
|
||
|
||
Only available expressions that set a single pseudo-reg are recorded.
|
||
|
||
Single sets in a PARALLEL could be handled, but it's an extra complication
|
||
that isn't dealt with right now. The trick is handling the CLOBBERs that
|
||
are also in the PARALLEL. Later.
|
||
|
||
If SET_P is nonzero, this is for the assignment hash table,
|
||
otherwise it is for the expression hash table.
|
||
If IN_LIBCALL_BLOCK nonzero, we are in a libcall block, and should
|
||
not record any expressions. */
|
||
|
||
static void
|
||
hash_scan_insn (rtx insn, struct hash_table *table, int in_libcall_block)
|
||
{
|
||
rtx pat = PATTERN (insn);
|
||
int i;
|
||
|
||
if (in_libcall_block)
|
||
return;
|
||
|
||
/* Pick out the sets of INSN and for other forms of instructions record
|
||
what's been modified. */
|
||
|
||
if (GET_CODE (pat) == SET)
|
||
hash_scan_set (pat, insn, table);
|
||
else if (GET_CODE (pat) == PARALLEL)
|
||
for (i = 0; i < XVECLEN (pat, 0); i++)
|
||
{
|
||
rtx x = XVECEXP (pat, 0, i);
|
||
|
||
if (GET_CODE (x) == SET)
|
||
hash_scan_set (x, insn, table);
|
||
else if (GET_CODE (x) == CLOBBER)
|
||
hash_scan_clobber (x, insn, table);
|
||
else if (GET_CODE (x) == CALL)
|
||
hash_scan_call (x, insn, table);
|
||
}
|
||
|
||
else if (GET_CODE (pat) == CLOBBER)
|
||
hash_scan_clobber (pat, insn, table);
|
||
else if (GET_CODE (pat) == CALL)
|
||
hash_scan_call (pat, insn, table);
|
||
}
|
||
|
||
static void
|
||
dump_hash_table (FILE *file, const char *name, struct hash_table *table)
|
||
{
|
||
int i;
|
||
/* Flattened out table, so it's printed in proper order. */
|
||
struct expr **flat_table;
|
||
unsigned int *hash_val;
|
||
struct expr *expr;
|
||
|
||
flat_table = xcalloc (table->n_elems, sizeof (struct expr *));
|
||
hash_val = xmalloc (table->n_elems * sizeof (unsigned int));
|
||
|
||
for (i = 0; i < (int) table->size; i++)
|
||
for (expr = table->table[i]; expr != NULL; expr = expr->next_same_hash)
|
||
{
|
||
flat_table[expr->bitmap_index] = expr;
|
||
hash_val[expr->bitmap_index] = i;
|
||
}
|
||
|
||
fprintf (file, "%s hash table (%d buckets, %d entries)\n",
|
||
name, table->size, table->n_elems);
|
||
|
||
for (i = 0; i < (int) table->n_elems; i++)
|
||
if (flat_table[i] != 0)
|
||
{
|
||
expr = flat_table[i];
|
||
fprintf (file, "Index %d (hash value %d)\n ",
|
||
expr->bitmap_index, hash_val[i]);
|
||
print_rtl (file, expr->expr);
|
||
fprintf (file, "\n");
|
||
}
|
||
|
||
fprintf (file, "\n");
|
||
|
||
free (flat_table);
|
||
free (hash_val);
|
||
}
|
||
|
||
/* Record register first/last/block set information for REGNO in INSN.
|
||
|
||
first_set records the first place in the block where the register
|
||
is set and is used to compute "anticipatability".
|
||
|
||
last_set records the last place in the block where the register
|
||
is set and is used to compute "availability".
|
||
|
||
last_bb records the block for which first_set and last_set are
|
||
valid, as a quick test to invalidate them.
|
||
|
||
reg_set_in_block records whether the register is set in the block
|
||
and is used to compute "transparency". */
|
||
|
||
static void
|
||
record_last_reg_set_info (rtx insn, int regno)
|
||
{
|
||
struct reg_avail_info *info = ®_avail_info[regno];
|
||
int cuid = INSN_CUID (insn);
|
||
|
||
info->last_set = cuid;
|
||
if (info->last_bb != current_bb)
|
||
{
|
||
info->last_bb = current_bb;
|
||
info->first_set = cuid;
|
||
SET_BIT (reg_set_in_block[current_bb->index], regno);
|
||
}
|
||
}
|
||
|
||
|
||
/* Record all of the canonicalized MEMs of record_last_mem_set_info's insn.
|
||
Note we store a pair of elements in the list, so they have to be
|
||
taken off pairwise. */
|
||
|
||
static void
|
||
canon_list_insert (rtx dest ATTRIBUTE_UNUSED, rtx unused1 ATTRIBUTE_UNUSED,
|
||
void * v_insn)
|
||
{
|
||
rtx dest_addr, insn;
|
||
int bb;
|
||
|
||
while (GET_CODE (dest) == SUBREG
|
||
|| GET_CODE (dest) == ZERO_EXTRACT
|
||
|| GET_CODE (dest) == SIGN_EXTRACT
|
||
|| GET_CODE (dest) == STRICT_LOW_PART)
|
||
dest = XEXP (dest, 0);
|
||
|
||
/* If DEST is not a MEM, then it will not conflict with a load. Note
|
||
that function calls are assumed to clobber memory, but are handled
|
||
elsewhere. */
|
||
|
||
if (GET_CODE (dest) != MEM)
|
||
return;
|
||
|
||
dest_addr = get_addr (XEXP (dest, 0));
|
||
dest_addr = canon_rtx (dest_addr);
|
||
insn = (rtx) v_insn;
|
||
bb = BLOCK_NUM (insn);
|
||
|
||
canon_modify_mem_list[bb] =
|
||
alloc_EXPR_LIST (VOIDmode, dest_addr, canon_modify_mem_list[bb]);
|
||
canon_modify_mem_list[bb] =
|
||
alloc_EXPR_LIST (VOIDmode, dest, canon_modify_mem_list[bb]);
|
||
bitmap_set_bit (canon_modify_mem_list_set, bb);
|
||
}
|
||
|
||
/* Record memory modification information for INSN. We do not actually care
|
||
about the memory location(s) that are set, or even how they are set (consider
|
||
a CALL_INSN). We merely need to record which insns modify memory. */
|
||
|
||
static void
|
||
record_last_mem_set_info (rtx insn)
|
||
{
|
||
int bb = BLOCK_NUM (insn);
|
||
|
||
/* load_killed_in_block_p will handle the case of calls clobbering
|
||
everything. */
|
||
modify_mem_list[bb] = alloc_INSN_LIST (insn, modify_mem_list[bb]);
|
||
bitmap_set_bit (modify_mem_list_set, bb);
|
||
|
||
if (GET_CODE (insn) == CALL_INSN)
|
||
{
|
||
/* Note that traversals of this loop (other than for free-ing)
|
||
will break after encountering a CALL_INSN. So, there's no
|
||
need to insert a pair of items, as canon_list_insert does. */
|
||
canon_modify_mem_list[bb] =
|
||
alloc_INSN_LIST (insn, canon_modify_mem_list[bb]);
|
||
bitmap_set_bit (canon_modify_mem_list_set, bb);
|
||
}
|
||
else
|
||
note_stores (PATTERN (insn), canon_list_insert, (void*) insn);
|
||
}
|
||
|
||
/* Called from compute_hash_table via note_stores to handle one
|
||
SET or CLOBBER in an insn. DATA is really the instruction in which
|
||
the SET is taking place. */
|
||
|
||
static void
|
||
record_last_set_info (rtx dest, rtx setter ATTRIBUTE_UNUSED, void *data)
|
||
{
|
||
rtx last_set_insn = (rtx) data;
|
||
|
||
if (GET_CODE (dest) == SUBREG)
|
||
dest = SUBREG_REG (dest);
|
||
|
||
if (GET_CODE (dest) == REG)
|
||
record_last_reg_set_info (last_set_insn, REGNO (dest));
|
||
else if (GET_CODE (dest) == MEM
|
||
/* Ignore pushes, they clobber nothing. */
|
||
&& ! push_operand (dest, GET_MODE (dest)))
|
||
record_last_mem_set_info (last_set_insn);
|
||
}
|
||
|
||
/* Top level function to create an expression or assignment hash table.
|
||
|
||
Expression entries are placed in the hash table if
|
||
- they are of the form (set (pseudo-reg) src),
|
||
- src is something we want to perform GCSE on,
|
||
- none of the operands are subsequently modified in the block
|
||
|
||
Assignment entries are placed in the hash table if
|
||
- they are of the form (set (pseudo-reg) src),
|
||
- src is something we want to perform const/copy propagation on,
|
||
- none of the operands or target are subsequently modified in the block
|
||
|
||
Currently src must be a pseudo-reg or a const_int.
|
||
|
||
TABLE is the table computed. */
|
||
|
||
static void
|
||
compute_hash_table_work (struct hash_table *table)
|
||
{
|
||
unsigned int i;
|
||
|
||
/* While we compute the hash table we also compute a bit array of which
|
||
registers are set in which blocks.
|
||
??? This isn't needed during const/copy propagation, but it's cheap to
|
||
compute. Later. */
|
||
sbitmap_vector_zero (reg_set_in_block, last_basic_block);
|
||
|
||
/* re-Cache any INSN_LIST nodes we have allocated. */
|
||
clear_modify_mem_tables ();
|
||
/* Some working arrays used to track first and last set in each block. */
|
||
reg_avail_info = gmalloc (max_gcse_regno * sizeof (struct reg_avail_info));
|
||
|
||
for (i = 0; i < max_gcse_regno; ++i)
|
||
reg_avail_info[i].last_bb = NULL;
|
||
|
||
FOR_EACH_BB (current_bb)
|
||
{
|
||
rtx insn;
|
||
unsigned int regno;
|
||
int in_libcall_block;
|
||
|
||
/* First pass over the instructions records information used to
|
||
determine when registers and memory are first and last set.
|
||
??? hard-reg reg_set_in_block computation
|
||
could be moved to compute_sets since they currently don't change. */
|
||
|
||
for (insn = BB_HEAD (current_bb);
|
||
insn && insn != NEXT_INSN (BB_END (current_bb));
|
||
insn = NEXT_INSN (insn))
|
||
{
|
||
if (! INSN_P (insn))
|
||
continue;
|
||
|
||
if (GET_CODE (insn) == CALL_INSN)
|
||
{
|
||
bool clobbers_all = false;
|
||
#ifdef NON_SAVING_SETJMP
|
||
if (NON_SAVING_SETJMP
|
||
&& find_reg_note (insn, REG_SETJMP, NULL_RTX))
|
||
clobbers_all = true;
|
||
#endif
|
||
|
||
for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
|
||
if (clobbers_all
|
||
|| TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
|
||
record_last_reg_set_info (insn, regno);
|
||
|
||
mark_call (insn);
|
||
}
|
||
|
||
note_stores (PATTERN (insn), record_last_set_info, insn);
|
||
}
|
||
|
||
/* Insert implicit sets in the hash table. */
|
||
if (table->set_p
|
||
&& implicit_sets[current_bb->index] != NULL_RTX)
|
||
hash_scan_set (implicit_sets[current_bb->index],
|
||
BB_HEAD (current_bb), table);
|
||
|
||
/* The next pass builds the hash table. */
|
||
|
||
for (insn = BB_HEAD (current_bb), in_libcall_block = 0;
|
||
insn && insn != NEXT_INSN (BB_END (current_bb));
|
||
insn = NEXT_INSN (insn))
|
||
if (INSN_P (insn))
|
||
{
|
||
if (find_reg_note (insn, REG_LIBCALL, NULL_RTX))
|
||
in_libcall_block = 1;
|
||
else if (table->set_p && find_reg_note (insn, REG_RETVAL, NULL_RTX))
|
||
in_libcall_block = 0;
|
||
hash_scan_insn (insn, table, in_libcall_block);
|
||
if (!table->set_p && find_reg_note (insn, REG_RETVAL, NULL_RTX))
|
||
in_libcall_block = 0;
|
||
}
|
||
}
|
||
|
||
free (reg_avail_info);
|
||
reg_avail_info = NULL;
|
||
}
|
||
|
||
/* Allocate space for the set/expr hash TABLE.
|
||
N_INSNS is the number of instructions in the function.
|
||
It is used to determine the number of buckets to use.
|
||
SET_P determines whether set or expression table will
|
||
be created. */
|
||
|
||
static void
|
||
alloc_hash_table (int n_insns, struct hash_table *table, int set_p)
|
||
{
|
||
int n;
|
||
|
||
table->size = n_insns / 4;
|
||
if (table->size < 11)
|
||
table->size = 11;
|
||
|
||
/* Attempt to maintain efficient use of hash table.
|
||
Making it an odd number is simplest for now.
|
||
??? Later take some measurements. */
|
||
table->size |= 1;
|
||
n = table->size * sizeof (struct expr *);
|
||
table->table = gmalloc (n);
|
||
table->set_p = set_p;
|
||
}
|
||
|
||
/* Free things allocated by alloc_hash_table. */
|
||
|
||
static void
|
||
free_hash_table (struct hash_table *table)
|
||
{
|
||
free (table->table);
|
||
}
|
||
|
||
/* Compute the hash TABLE for doing copy/const propagation or
|
||
expression hash table. */
|
||
|
||
static void
|
||
compute_hash_table (struct hash_table *table)
|
||
{
|
||
/* Initialize count of number of entries in hash table. */
|
||
table->n_elems = 0;
|
||
memset (table->table, 0, table->size * sizeof (struct expr *));
|
||
|
||
compute_hash_table_work (table);
|
||
}
|
||
|
||
/* Expression tracking support. */
|
||
|
||
/* Lookup pattern PAT in the expression TABLE.
|
||
The result is a pointer to the table entry, or NULL if not found. */
|
||
|
||
static struct expr *
|
||
lookup_expr (rtx pat, struct hash_table *table)
|
||
{
|
||
int do_not_record_p;
|
||
unsigned int hash = hash_expr (pat, GET_MODE (pat), &do_not_record_p,
|
||
table->size);
|
||
struct expr *expr;
|
||
|
||
if (do_not_record_p)
|
||
return NULL;
|
||
|
||
expr = table->table[hash];
|
||
|
||
while (expr && ! expr_equiv_p (expr->expr, pat))
|
||
expr = expr->next_same_hash;
|
||
|
||
return expr;
|
||
}
|
||
|
||
/* Lookup REGNO in the set TABLE. The result is a pointer to the
|
||
table entry, or NULL if not found. */
|
||
|
||
static struct expr *
|
||
lookup_set (unsigned int regno, struct hash_table *table)
|
||
{
|
||
unsigned int hash = hash_set (regno, table->size);
|
||
struct expr *expr;
|
||
|
||
expr = table->table[hash];
|
||
|
||
while (expr && REGNO (SET_DEST (expr->expr)) != regno)
|
||
expr = expr->next_same_hash;
|
||
|
||
return expr;
|
||
}
|
||
|
||
/* Return the next entry for REGNO in list EXPR. */
|
||
|
||
static struct expr *
|
||
next_set (unsigned int regno, struct expr *expr)
|
||
{
|
||
do
|
||
expr = expr->next_same_hash;
|
||
while (expr && REGNO (SET_DEST (expr->expr)) != regno);
|
||
|
||
return expr;
|
||
}
|
||
|
||
/* Like free_INSN_LIST_list or free_EXPR_LIST_list, except that the node
|
||
types may be mixed. */
|
||
|
||
static void
|
||
free_insn_expr_list_list (rtx *listp)
|
||
{
|
||
rtx list, next;
|
||
|
||
for (list = *listp; list ; list = next)
|
||
{
|
||
next = XEXP (list, 1);
|
||
if (GET_CODE (list) == EXPR_LIST)
|
||
free_EXPR_LIST_node (list);
|
||
else
|
||
free_INSN_LIST_node (list);
|
||
}
|
||
|
||
*listp = NULL;
|
||
}
|
||
|
||
/* Clear canon_modify_mem_list and modify_mem_list tables. */
|
||
static void
|
||
clear_modify_mem_tables (void)
|
||
{
|
||
int i;
|
||
|
||
EXECUTE_IF_SET_IN_BITMAP
|
||
(modify_mem_list_set, 0, i, free_INSN_LIST_list (modify_mem_list + i));
|
||
bitmap_clear (modify_mem_list_set);
|
||
|
||
EXECUTE_IF_SET_IN_BITMAP
|
||
(canon_modify_mem_list_set, 0, i,
|
||
free_insn_expr_list_list (canon_modify_mem_list + i));
|
||
bitmap_clear (canon_modify_mem_list_set);
|
||
}
|
||
|
||
/* Release memory used by modify_mem_list_set and canon_modify_mem_list_set. */
|
||
|
||
static void
|
||
free_modify_mem_tables (void)
|
||
{
|
||
clear_modify_mem_tables ();
|
||
free (modify_mem_list);
|
||
free (canon_modify_mem_list);
|
||
modify_mem_list = 0;
|
||
canon_modify_mem_list = 0;
|
||
}
|
||
|
||
/* Reset tables used to keep track of what's still available [since the
|
||
start of the block]. */
|
||
|
||
static void
|
||
reset_opr_set_tables (void)
|
||
{
|
||
/* Maintain a bitmap of which regs have been set since beginning of
|
||
the block. */
|
||
CLEAR_REG_SET (reg_set_bitmap);
|
||
|
||
/* Also keep a record of the last instruction to modify memory.
|
||
For now this is very trivial, we only record whether any memory
|
||
location has been modified. */
|
||
clear_modify_mem_tables ();
|
||
}
|
||
|
||
/* Return nonzero if the operands of X are not set before INSN in
|
||
INSN's basic block. */
|
||
|
||
static int
|
||
oprs_not_set_p (rtx x, rtx insn)
|
||
{
|
||
int i, j;
|
||
enum rtx_code code;
|
||
const char *fmt;
|
||
|
||
if (x == 0)
|
||
return 1;
|
||
|
||
code = GET_CODE (x);
|
||
switch (code)
|
||
{
|
||
case PC:
|
||
case CC0:
|
||
case CONST:
|
||
case CONST_INT:
|
||
case CONST_DOUBLE:
|
||
case CONST_VECTOR:
|
||
case SYMBOL_REF:
|
||
case LABEL_REF:
|
||
case ADDR_VEC:
|
||
case ADDR_DIFF_VEC:
|
||
return 1;
|
||
|
||
case MEM:
|
||
if (load_killed_in_block_p (BLOCK_FOR_INSN (insn),
|
||
INSN_CUID (insn), x, 0))
|
||
return 0;
|
||
else
|
||
return oprs_not_set_p (XEXP (x, 0), insn);
|
||
|
||
case REG:
|
||
return ! REGNO_REG_SET_P (reg_set_bitmap, REGNO (x));
|
||
|
||
default:
|
||
break;
|
||
}
|
||
|
||
for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
|
||
{
|
||
if (fmt[i] == 'e')
|
||
{
|
||
/* If we are about to do the last recursive call
|
||
needed at this level, change it into iteration.
|
||
This function is called enough to be worth it. */
|
||
if (i == 0)
|
||
return oprs_not_set_p (XEXP (x, i), insn);
|
||
|
||
if (! oprs_not_set_p (XEXP (x, i), insn))
|
||
return 0;
|
||
}
|
||
else if (fmt[i] == 'E')
|
||
for (j = 0; j < XVECLEN (x, i); j++)
|
||
if (! oprs_not_set_p (XVECEXP (x, i, j), insn))
|
||
return 0;
|
||
}
|
||
|
||
return 1;
|
||
}
|
||
|
||
/* Mark things set by a CALL. */
|
||
|
||
static void
|
||
mark_call (rtx insn)
|
||
{
|
||
if (! CONST_OR_PURE_CALL_P (insn))
|
||
record_last_mem_set_info (insn);
|
||
}
|
||
|
||
/* Mark things set by a SET. */
|
||
|
||
static void
|
||
mark_set (rtx pat, rtx insn)
|
||
{
|
||
rtx dest = SET_DEST (pat);
|
||
|
||
while (GET_CODE (dest) == SUBREG
|
||
|| GET_CODE (dest) == ZERO_EXTRACT
|
||
|| GET_CODE (dest) == SIGN_EXTRACT
|
||
|| GET_CODE (dest) == STRICT_LOW_PART)
|
||
dest = XEXP (dest, 0);
|
||
|
||
if (GET_CODE (dest) == REG)
|
||
SET_REGNO_REG_SET (reg_set_bitmap, REGNO (dest));
|
||
else if (GET_CODE (dest) == MEM)
|
||
record_last_mem_set_info (insn);
|
||
|
||
if (GET_CODE (SET_SRC (pat)) == CALL)
|
||
mark_call (insn);
|
||
}
|
||
|
||
/* Record things set by a CLOBBER. */
|
||
|
||
static void
|
||
mark_clobber (rtx pat, rtx insn)
|
||
{
|
||
rtx clob = XEXP (pat, 0);
|
||
|
||
while (GET_CODE (clob) == SUBREG || GET_CODE (clob) == STRICT_LOW_PART)
|
||
clob = XEXP (clob, 0);
|
||
|
||
if (GET_CODE (clob) == REG)
|
||
SET_REGNO_REG_SET (reg_set_bitmap, REGNO (clob));
|
||
else
|
||
record_last_mem_set_info (insn);
|
||
}
|
||
|
||
/* Record things set by INSN.
|
||
This data is used by oprs_not_set_p. */
|
||
|
||
static void
|
||
mark_oprs_set (rtx insn)
|
||
{
|
||
rtx pat = PATTERN (insn);
|
||
int i;
|
||
|
||
if (GET_CODE (pat) == SET)
|
||
mark_set (pat, insn);
|
||
else if (GET_CODE (pat) == PARALLEL)
|
||
for (i = 0; i < XVECLEN (pat, 0); i++)
|
||
{
|
||
rtx x = XVECEXP (pat, 0, i);
|
||
|
||
if (GET_CODE (x) == SET)
|
||
mark_set (x, insn);
|
||
else if (GET_CODE (x) == CLOBBER)
|
||
mark_clobber (x, insn);
|
||
else if (GET_CODE (x) == CALL)
|
||
mark_call (insn);
|
||
}
|
||
|
||
else if (GET_CODE (pat) == CLOBBER)
|
||
mark_clobber (pat, insn);
|
||
else if (GET_CODE (pat) == CALL)
|
||
mark_call (insn);
|
||
}
|
||
|
||
|
||
/* Classic GCSE reaching definition support. */
|
||
|
||
/* Allocate reaching def variables. */
|
||
|
||
static void
|
||
alloc_rd_mem (int n_blocks, int n_insns)
|
||
{
|
||
rd_kill = sbitmap_vector_alloc (n_blocks, n_insns);
|
||
sbitmap_vector_zero (rd_kill, n_blocks);
|
||
|
||
rd_gen = sbitmap_vector_alloc (n_blocks, n_insns);
|
||
sbitmap_vector_zero (rd_gen, n_blocks);
|
||
|
||
reaching_defs = sbitmap_vector_alloc (n_blocks, n_insns);
|
||
sbitmap_vector_zero (reaching_defs, n_blocks);
|
||
|
||
rd_out = sbitmap_vector_alloc (n_blocks, n_insns);
|
||
sbitmap_vector_zero (rd_out, n_blocks);
|
||
}
|
||
|
||
/* Free reaching def variables. */
|
||
|
||
static void
|
||
free_rd_mem (void)
|
||
{
|
||
sbitmap_vector_free (rd_kill);
|
||
sbitmap_vector_free (rd_gen);
|
||
sbitmap_vector_free (reaching_defs);
|
||
sbitmap_vector_free (rd_out);
|
||
}
|
||
|
||
/* Add INSN to the kills of BB. REGNO, set in BB, is killed by INSN. */
|
||
|
||
static void
|
||
handle_rd_kill_set (rtx insn, int regno, basic_block bb)
|
||
{
|
||
struct reg_set *this_reg;
|
||
|
||
for (this_reg = reg_set_table[regno]; this_reg; this_reg = this_reg ->next)
|
||
if (BLOCK_NUM (this_reg->insn) != BLOCK_NUM (insn))
|
||
SET_BIT (rd_kill[bb->index], INSN_CUID (this_reg->insn));
|
||
}
|
||
|
||
/* Compute the set of kill's for reaching definitions. */
|
||
|
||
static void
|
||
compute_kill_rd (void)
|
||
{
|
||
int cuid;
|
||
unsigned int regno;
|
||
int i;
|
||
basic_block bb;
|
||
|
||
/* For each block
|
||
For each set bit in `gen' of the block (i.e each insn which
|
||
generates a definition in the block)
|
||
Call the reg set by the insn corresponding to that bit regx
|
||
Look at the linked list starting at reg_set_table[regx]
|
||
For each setting of regx in the linked list, which is not in
|
||
this block
|
||
Set the bit in `kill' corresponding to that insn. */
|
||
FOR_EACH_BB (bb)
|
||
for (cuid = 0; cuid < max_cuid; cuid++)
|
||
if (TEST_BIT (rd_gen[bb->index], cuid))
|
||
{
|
||
rtx insn = CUID_INSN (cuid);
|
||
rtx pat = PATTERN (insn);
|
||
|
||
if (GET_CODE (insn) == CALL_INSN)
|
||
{
|
||
for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
|
||
if (TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
|
||
handle_rd_kill_set (insn, regno, bb);
|
||
}
|
||
|
||
if (GET_CODE (pat) == PARALLEL)
|
||
{
|
||
for (i = XVECLEN (pat, 0) - 1; i >= 0; i--)
|
||
{
|
||
enum rtx_code code = GET_CODE (XVECEXP (pat, 0, i));
|
||
|
||
if ((code == SET || code == CLOBBER)
|
||
&& GET_CODE (XEXP (XVECEXP (pat, 0, i), 0)) == REG)
|
||
handle_rd_kill_set (insn,
|
||
REGNO (XEXP (XVECEXP (pat, 0, i), 0)),
|
||
bb);
|
||
}
|
||
}
|
||
else if (GET_CODE (pat) == SET && GET_CODE (SET_DEST (pat)) == REG)
|
||
/* Each setting of this register outside of this block
|
||
must be marked in the set of kills in this block. */
|
||
handle_rd_kill_set (insn, REGNO (SET_DEST (pat)), bb);
|
||
}
|
||
}
|
||
|
||
/* Compute the reaching definitions as in
|
||
Compilers Principles, Techniques, and Tools. Aho, Sethi, Ullman,
|
||
Chapter 10. It is the same algorithm as used for computing available
|
||
expressions but applied to the gens and kills of reaching definitions. */
|
||
|
||
static void
|
||
compute_rd (void)
|
||
{
|
||
int changed, passes;
|
||
basic_block bb;
|
||
|
||
FOR_EACH_BB (bb)
|
||
sbitmap_copy (rd_out[bb->index] /*dst*/, rd_gen[bb->index] /*src*/);
|
||
|
||
passes = 0;
|
||
changed = 1;
|
||
while (changed)
|
||
{
|
||
changed = 0;
|
||
FOR_EACH_BB (bb)
|
||
{
|
||
sbitmap_union_of_preds (reaching_defs[bb->index], rd_out, bb->index);
|
||
changed |= sbitmap_union_of_diff_cg (rd_out[bb->index], rd_gen[bb->index],
|
||
reaching_defs[bb->index], rd_kill[bb->index]);
|
||
}
|
||
passes++;
|
||
}
|
||
|
||
if (gcse_file)
|
||
fprintf (gcse_file, "reaching def computation: %d passes\n", passes);
|
||
}
|
||
|
||
/* Classic GCSE available expression support. */
|
||
|
||
/* Allocate memory for available expression computation. */
|
||
|
||
static void
|
||
alloc_avail_expr_mem (int n_blocks, int n_exprs)
|
||
{
|
||
ae_kill = sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
sbitmap_vector_zero (ae_kill, n_blocks);
|
||
|
||
ae_gen = sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
sbitmap_vector_zero (ae_gen, n_blocks);
|
||
|
||
ae_in = sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
sbitmap_vector_zero (ae_in, n_blocks);
|
||
|
||
ae_out = sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
sbitmap_vector_zero (ae_out, n_blocks);
|
||
}
|
||
|
||
static void
|
||
free_avail_expr_mem (void)
|
||
{
|
||
sbitmap_vector_free (ae_kill);
|
||
sbitmap_vector_free (ae_gen);
|
||
sbitmap_vector_free (ae_in);
|
||
sbitmap_vector_free (ae_out);
|
||
}
|
||
|
||
/* Compute the set of available expressions generated in each basic block. */
|
||
|
||
static void
|
||
compute_ae_gen (struct hash_table *expr_hash_table)
|
||
{
|
||
unsigned int i;
|
||
struct expr *expr;
|
||
struct occr *occr;
|
||
|
||
/* For each recorded occurrence of each expression, set ae_gen[bb][expr].
|
||
This is all we have to do because an expression is not recorded if it
|
||
is not available, and the only expressions we want to work with are the
|
||
ones that are recorded. */
|
||
for (i = 0; i < expr_hash_table->size; i++)
|
||
for (expr = expr_hash_table->table[i]; expr != 0; expr = expr->next_same_hash)
|
||
for (occr = expr->avail_occr; occr != 0; occr = occr->next)
|
||
SET_BIT (ae_gen[BLOCK_NUM (occr->insn)], expr->bitmap_index);
|
||
}
|
||
|
||
/* Return nonzero if expression X is killed in BB. */
|
||
|
||
static int
|
||
expr_killed_p (rtx x, basic_block bb)
|
||
{
|
||
int i, j;
|
||
enum rtx_code code;
|
||
const char *fmt;
|
||
|
||
if (x == 0)
|
||
return 1;
|
||
|
||
code = GET_CODE (x);
|
||
switch (code)
|
||
{
|
||
case REG:
|
||
return TEST_BIT (reg_set_in_block[bb->index], REGNO (x));
|
||
|
||
case MEM:
|
||
if (load_killed_in_block_p (bb, get_max_uid () + 1, x, 0))
|
||
return 1;
|
||
else
|
||
return expr_killed_p (XEXP (x, 0), bb);
|
||
|
||
case PC:
|
||
case CC0: /*FIXME*/
|
||
case CONST:
|
||
case CONST_INT:
|
||
case CONST_DOUBLE:
|
||
case CONST_VECTOR:
|
||
case SYMBOL_REF:
|
||
case LABEL_REF:
|
||
case ADDR_VEC:
|
||
case ADDR_DIFF_VEC:
|
||
return 0;
|
||
|
||
default:
|
||
break;
|
||
}
|
||
|
||
for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
|
||
{
|
||
if (fmt[i] == 'e')
|
||
{
|
||
/* If we are about to do the last recursive call
|
||
needed at this level, change it into iteration.
|
||
This function is called enough to be worth it. */
|
||
if (i == 0)
|
||
return expr_killed_p (XEXP (x, i), bb);
|
||
else if (expr_killed_p (XEXP (x, i), bb))
|
||
return 1;
|
||
}
|
||
else if (fmt[i] == 'E')
|
||
for (j = 0; j < XVECLEN (x, i); j++)
|
||
if (expr_killed_p (XVECEXP (x, i, j), bb))
|
||
return 1;
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
/* Compute the set of available expressions killed in each basic block. */
|
||
|
||
static void
|
||
compute_ae_kill (sbitmap *ae_gen, sbitmap *ae_kill,
|
||
struct hash_table *expr_hash_table)
|
||
{
|
||
basic_block bb;
|
||
unsigned int i;
|
||
struct expr *expr;
|
||
|
||
FOR_EACH_BB (bb)
|
||
for (i = 0; i < expr_hash_table->size; i++)
|
||
for (expr = expr_hash_table->table[i]; expr; expr = expr->next_same_hash)
|
||
{
|
||
/* Skip EXPR if generated in this block. */
|
||
if (TEST_BIT (ae_gen[bb->index], expr->bitmap_index))
|
||
continue;
|
||
|
||
if (expr_killed_p (expr->expr, bb))
|
||
SET_BIT (ae_kill[bb->index], expr->bitmap_index);
|
||
}
|
||
}
|
||
|
||
/* Actually perform the Classic GCSE optimizations. */
|
||
|
||
/* Return nonzero if occurrence OCCR of expression EXPR reaches block BB.
|
||
|
||
CHECK_SELF_LOOP is nonzero if we should consider a block reaching itself
|
||
as a positive reach. We want to do this when there are two computations
|
||
of the expression in the block.
|
||
|
||
VISITED is a pointer to a working buffer for tracking which BB's have
|
||
been visited. It is NULL for the top-level call.
|
||
|
||
We treat reaching expressions that go through blocks containing the same
|
||
reaching expression as "not reaching". E.g. if EXPR is generated in blocks
|
||
2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
|
||
2 as not reaching. The intent is to improve the probability of finding
|
||
only one reaching expression and to reduce register lifetimes by picking
|
||
the closest such expression. */
|
||
|
||
static int
|
||
expr_reaches_here_p_work (struct occr *occr, struct expr *expr,
|
||
basic_block bb, int check_self_loop, char *visited)
|
||
{
|
||
edge pred;
|
||
|
||
for (pred = bb->pred; pred != NULL; pred = pred->pred_next)
|
||
{
|
||
basic_block pred_bb = pred->src;
|
||
|
||
if (visited[pred_bb->index])
|
||
/* This predecessor has already been visited. Nothing to do. */
|
||
;
|
||
else if (pred_bb == bb)
|
||
{
|
||
/* BB loops on itself. */
|
||
if (check_self_loop
|
||
&& TEST_BIT (ae_gen[pred_bb->index], expr->bitmap_index)
|
||
&& BLOCK_NUM (occr->insn) == pred_bb->index)
|
||
return 1;
|
||
|
||
visited[pred_bb->index] = 1;
|
||
}
|
||
|
||
/* Ignore this predecessor if it kills the expression. */
|
||
else if (TEST_BIT (ae_kill[pred_bb->index], expr->bitmap_index))
|
||
visited[pred_bb->index] = 1;
|
||
|
||
/* Does this predecessor generate this expression? */
|
||
else if (TEST_BIT (ae_gen[pred_bb->index], expr->bitmap_index))
|
||
{
|
||
/* Is this the occurrence we're looking for?
|
||
Note that there's only one generating occurrence per block
|
||
so we just need to check the block number. */
|
||
if (BLOCK_NUM (occr->insn) == pred_bb->index)
|
||
return 1;
|
||
|
||
visited[pred_bb->index] = 1;
|
||
}
|
||
|
||
/* Neither gen nor kill. */
|
||
else
|
||
{
|
||
visited[pred_bb->index] = 1;
|
||
if (expr_reaches_here_p_work (occr, expr, pred_bb, check_self_loop,
|
||
visited))
|
||
|
||
return 1;
|
||
}
|
||
}
|
||
|
||
/* All paths have been checked. */
|
||
return 0;
|
||
}
|
||
|
||
/* This wrapper for expr_reaches_here_p_work() is to ensure that any
|
||
memory allocated for that function is returned. */
|
||
|
||
static int
|
||
expr_reaches_here_p (struct occr *occr, struct expr *expr, basic_block bb,
|
||
int check_self_loop)
|
||
{
|
||
int rval;
|
||
char *visited = xcalloc (last_basic_block, 1);
|
||
|
||
rval = expr_reaches_here_p_work (occr, expr, bb, check_self_loop, visited);
|
||
|
||
free (visited);
|
||
return rval;
|
||
}
|
||
|
||
/* Return the instruction that computes EXPR that reaches INSN's basic block.
|
||
If there is more than one such instruction, return NULL.
|
||
|
||
Called only by handle_avail_expr. */
|
||
|
||
static rtx
|
||
computing_insn (struct expr *expr, rtx insn)
|
||
{
|
||
basic_block bb = BLOCK_FOR_INSN (insn);
|
||
|
||
if (expr->avail_occr->next == NULL)
|
||
{
|
||
if (BLOCK_FOR_INSN (expr->avail_occr->insn) == bb)
|
||
/* The available expression is actually itself
|
||
(i.e. a loop in the flow graph) so do nothing. */
|
||
return NULL;
|
||
|
||
/* (FIXME) Case that we found a pattern that was created by
|
||
a substitution that took place. */
|
||
return expr->avail_occr->insn;
|
||
}
|
||
else
|
||
{
|
||
/* Pattern is computed more than once.
|
||
Search backwards from this insn to see how many of these
|
||
computations actually reach this insn. */
|
||
struct occr *occr;
|
||
rtx insn_computes_expr = NULL;
|
||
int can_reach = 0;
|
||
|
||
for (occr = expr->avail_occr; occr != NULL; occr = occr->next)
|
||
{
|
||
if (BLOCK_FOR_INSN (occr->insn) == bb)
|
||
{
|
||
/* The expression is generated in this block.
|
||
The only time we care about this is when the expression
|
||
is generated later in the block [and thus there's a loop].
|
||
We let the normal cse pass handle the other cases. */
|
||
if (INSN_CUID (insn) < INSN_CUID (occr->insn)
|
||
&& expr_reaches_here_p (occr, expr, bb, 1))
|
||
{
|
||
can_reach++;
|
||
if (can_reach > 1)
|
||
return NULL;
|
||
|
||
insn_computes_expr = occr->insn;
|
||
}
|
||
}
|
||
else if (expr_reaches_here_p (occr, expr, bb, 0))
|
||
{
|
||
can_reach++;
|
||
if (can_reach > 1)
|
||
return NULL;
|
||
|
||
insn_computes_expr = occr->insn;
|
||
}
|
||
}
|
||
|
||
if (insn_computes_expr == NULL)
|
||
abort ();
|
||
|
||
return insn_computes_expr;
|
||
}
|
||
}
|
||
|
||
/* Return nonzero if the definition in DEF_INSN can reach INSN.
|
||
Only called by can_disregard_other_sets. */
|
||
|
||
static int
|
||
def_reaches_here_p (rtx insn, rtx def_insn)
|
||
{
|
||
rtx reg;
|
||
|
||
if (TEST_BIT (reaching_defs[BLOCK_NUM (insn)], INSN_CUID (def_insn)))
|
||
return 1;
|
||
|
||
if (BLOCK_NUM (insn) == BLOCK_NUM (def_insn))
|
||
{
|
||
if (INSN_CUID (def_insn) < INSN_CUID (insn))
|
||
{
|
||
if (GET_CODE (PATTERN (def_insn)) == PARALLEL)
|
||
return 1;
|
||
else if (GET_CODE (PATTERN (def_insn)) == CLOBBER)
|
||
reg = XEXP (PATTERN (def_insn), 0);
|
||
else if (GET_CODE (PATTERN (def_insn)) == SET)
|
||
reg = SET_DEST (PATTERN (def_insn));
|
||
else
|
||
abort ();
|
||
|
||
return ! reg_set_between_p (reg, NEXT_INSN (def_insn), insn);
|
||
}
|
||
else
|
||
return 0;
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
/* Return nonzero if *ADDR_THIS_REG can only have one value at INSN. The
|
||
value returned is the number of definitions that reach INSN. Returning a
|
||
value of zero means that [maybe] more than one definition reaches INSN and
|
||
the caller can't perform whatever optimization it is trying. i.e. it is
|
||
always safe to return zero. */
|
||
|
||
static int
|
||
can_disregard_other_sets (struct reg_set **addr_this_reg, rtx insn, int for_combine)
|
||
{
|
||
int number_of_reaching_defs = 0;
|
||
struct reg_set *this_reg;
|
||
|
||
for (this_reg = *addr_this_reg; this_reg != 0; this_reg = this_reg->next)
|
||
if (def_reaches_here_p (insn, this_reg->insn))
|
||
{
|
||
number_of_reaching_defs++;
|
||
/* Ignore parallels for now. */
|
||
if (GET_CODE (PATTERN (this_reg->insn)) == PARALLEL)
|
||
return 0;
|
||
|
||
if (!for_combine
|
||
&& (GET_CODE (PATTERN (this_reg->insn)) == CLOBBER
|
||
|| ! rtx_equal_p (SET_SRC (PATTERN (this_reg->insn)),
|
||
SET_SRC (PATTERN (insn)))))
|
||
/* A setting of the reg to a different value reaches INSN. */
|
||
return 0;
|
||
|
||
if (number_of_reaching_defs > 1)
|
||
{
|
||
/* If in this setting the value the register is being set to is
|
||
equal to the previous value the register was set to and this
|
||
setting reaches the insn we are trying to do the substitution
|
||
on then we are ok. */
|
||
if (GET_CODE (PATTERN (this_reg->insn)) == CLOBBER)
|
||
return 0;
|
||
else if (! rtx_equal_p (SET_SRC (PATTERN (this_reg->insn)),
|
||
SET_SRC (PATTERN (insn))))
|
||
return 0;
|
||
}
|
||
|
||
*addr_this_reg = this_reg;
|
||
}
|
||
|
||
return number_of_reaching_defs;
|
||
}
|
||
|
||
/* Expression computed by insn is available and the substitution is legal,
|
||
so try to perform the substitution.
|
||
|
||
The result is nonzero if any changes were made. */
|
||
|
||
static int
|
||
handle_avail_expr (rtx insn, struct expr *expr)
|
||
{
|
||
rtx pat, insn_computes_expr, expr_set;
|
||
rtx to;
|
||
struct reg_set *this_reg;
|
||
int found_setting, use_src;
|
||
int changed = 0;
|
||
|
||
/* We only handle the case where one computation of the expression
|
||
reaches this instruction. */
|
||
insn_computes_expr = computing_insn (expr, insn);
|
||
if (insn_computes_expr == NULL)
|
||
return 0;
|
||
expr_set = single_set (insn_computes_expr);
|
||
/* The set might be in a parallel with multiple sets; we could
|
||
probably handle that, but there's currently no easy way to find
|
||
the relevant sub-expression. */
|
||
if (!expr_set)
|
||
return 0;
|
||
|
||
found_setting = 0;
|
||
use_src = 0;
|
||
|
||
/* At this point we know only one computation of EXPR outside of this
|
||
block reaches this insn. Now try to find a register that the
|
||
expression is computed into. */
|
||
if (GET_CODE (SET_SRC (expr_set)) == REG)
|
||
{
|
||
/* This is the case when the available expression that reaches
|
||
here has already been handled as an available expression. */
|
||
unsigned int regnum_for_replacing
|
||
= REGNO (SET_SRC (expr_set));
|
||
|
||
/* If the register was created by GCSE we can't use `reg_set_table',
|
||
however we know it's set only once. */
|
||
if (regnum_for_replacing >= max_gcse_regno
|
||
/* If the register the expression is computed into is set only once,
|
||
or only one set reaches this insn, we can use it. */
|
||
|| (((this_reg = reg_set_table[regnum_for_replacing]),
|
||
this_reg->next == NULL)
|
||
|| can_disregard_other_sets (&this_reg, insn, 0)))
|
||
{
|
||
use_src = 1;
|
||
found_setting = 1;
|
||
}
|
||
}
|
||
|
||
if (!found_setting)
|
||
{
|
||
unsigned int regnum_for_replacing
|
||
= REGNO (SET_DEST (expr_set));
|
||
|
||
/* This shouldn't happen. */
|
||
if (regnum_for_replacing >= max_gcse_regno)
|
||
abort ();
|
||
|
||
this_reg = reg_set_table[regnum_for_replacing];
|
||
|
||
/* If the register the expression is computed into is set only once,
|
||
or only one set reaches this insn, use it. */
|
||
if (this_reg->next == NULL
|
||
|| can_disregard_other_sets (&this_reg, insn, 0))
|
||
found_setting = 1;
|
||
}
|
||
|
||
if (found_setting)
|
||
{
|
||
pat = PATTERN (insn);
|
||
if (use_src)
|
||
to = SET_SRC (expr_set);
|
||
else
|
||
to = SET_DEST (expr_set);
|
||
changed = validate_change (insn, &SET_SRC (pat), to, 0);
|
||
|
||
/* We should be able to ignore the return code from validate_change but
|
||
to play it safe we check. */
|
||
if (changed)
|
||
{
|
||
gcse_subst_count++;
|
||
if (gcse_file != NULL)
|
||
{
|
||
fprintf (gcse_file, "GCSE: Replacing the source in insn %d with",
|
||
INSN_UID (insn));
|
||
fprintf (gcse_file, " reg %d %s insn %d\n",
|
||
REGNO (to), use_src ? "from" : "set in",
|
||
INSN_UID (insn_computes_expr));
|
||
}
|
||
}
|
||
}
|
||
|
||
/* The register that the expr is computed into is set more than once. */
|
||
else if (1 /*expensive_op(this_pattrn->op) && do_expensive_gcse)*/)
|
||
{
|
||
/* Insert an insn after insnx that copies the reg set in insnx
|
||
into a new pseudo register call this new register REGN.
|
||
From insnb until end of basic block or until REGB is set
|
||
replace all uses of REGB with REGN. */
|
||
rtx new_insn;
|
||
|
||
to = gen_reg_rtx (GET_MODE (SET_DEST (expr_set)));
|
||
|
||
/* Generate the new insn. */
|
||
/* ??? If the change fails, we return 0, even though we created
|
||
an insn. I think this is ok. */
|
||
new_insn
|
||
= emit_insn_after (gen_rtx_SET (VOIDmode, to,
|
||
SET_DEST (expr_set)),
|
||
insn_computes_expr);
|
||
|
||
/* Keep register set table up to date. */
|
||
record_one_set (REGNO (to), new_insn);
|
||
|
||
gcse_create_count++;
|
||
if (gcse_file != NULL)
|
||
{
|
||
fprintf (gcse_file, "GCSE: Creating insn %d to copy value of reg %d",
|
||
INSN_UID (NEXT_INSN (insn_computes_expr)),
|
||
REGNO (SET_SRC (PATTERN (NEXT_INSN (insn_computes_expr)))));
|
||
fprintf (gcse_file, ", computed in insn %d,\n",
|
||
INSN_UID (insn_computes_expr));
|
||
fprintf (gcse_file, " into newly allocated reg %d\n",
|
||
REGNO (to));
|
||
}
|
||
|
||
pat = PATTERN (insn);
|
||
|
||
/* Do register replacement for INSN. */
|
||
changed = validate_change (insn, &SET_SRC (pat),
|
||
SET_DEST (PATTERN
|
||
(NEXT_INSN (insn_computes_expr))),
|
||
0);
|
||
|
||
/* We should be able to ignore the return code from validate_change but
|
||
to play it safe we check. */
|
||
if (changed)
|
||
{
|
||
gcse_subst_count++;
|
||
if (gcse_file != NULL)
|
||
{
|
||
fprintf (gcse_file,
|
||
"GCSE: Replacing the source in insn %d with reg %d ",
|
||
INSN_UID (insn),
|
||
REGNO (SET_DEST (PATTERN (NEXT_INSN
|
||
(insn_computes_expr)))));
|
||
fprintf (gcse_file, "set in insn %d\n",
|
||
INSN_UID (insn_computes_expr));
|
||
}
|
||
}
|
||
}
|
||
|
||
return changed;
|
||
}
|
||
|
||
/* Perform classic GCSE. This is called by one_classic_gcse_pass after all
|
||
the dataflow analysis has been done.
|
||
|
||
The result is nonzero if a change was made. */
|
||
|
||
static int
|
||
classic_gcse (void)
|
||
{
|
||
int changed;
|
||
rtx insn;
|
||
basic_block bb;
|
||
|
||
/* Note we start at block 1. */
|
||
|
||
if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
|
||
return 0;
|
||
|
||
changed = 0;
|
||
FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb, EXIT_BLOCK_PTR, next_bb)
|
||
{
|
||
/* Reset tables used to keep track of what's still valid [since the
|
||
start of the block]. */
|
||
reset_opr_set_tables ();
|
||
|
||
for (insn = BB_HEAD (bb);
|
||
insn != NULL && insn != NEXT_INSN (BB_END (bb));
|
||
insn = NEXT_INSN (insn))
|
||
{
|
||
/* Is insn of form (set (pseudo-reg) ...)? */
|
||
if (GET_CODE (insn) == INSN
|
||
&& GET_CODE (PATTERN (insn)) == SET
|
||
&& GET_CODE (SET_DEST (PATTERN (insn))) == REG
|
||
&& REGNO (SET_DEST (PATTERN (insn))) >= FIRST_PSEUDO_REGISTER)
|
||
{
|
||
rtx pat = PATTERN (insn);
|
||
rtx src = SET_SRC (pat);
|
||
struct expr *expr;
|
||
|
||
if (want_to_gcse_p (src)
|
||
/* Is the expression recorded? */
|
||
&& ((expr = lookup_expr (src, &expr_hash_table)) != NULL)
|
||
/* Is the expression available [at the start of the
|
||
block]? */
|
||
&& TEST_BIT (ae_in[bb->index], expr->bitmap_index)
|
||
/* Are the operands unchanged since the start of the
|
||
block? */
|
||
&& oprs_not_set_p (src, insn))
|
||
changed |= handle_avail_expr (insn, expr);
|
||
}
|
||
|
||
/* Keep track of everything modified by this insn. */
|
||
/* ??? Need to be careful w.r.t. mods done to INSN. */
|
||
if (INSN_P (insn))
|
||
mark_oprs_set (insn);
|
||
}
|
||
}
|
||
|
||
return changed;
|
||
}
|
||
|
||
/* Top level routine to perform one classic GCSE pass.
|
||
|
||
Return nonzero if a change was made. */
|
||
|
||
static int
|
||
one_classic_gcse_pass (int pass)
|
||
{
|
||
int changed = 0;
|
||
|
||
gcse_subst_count = 0;
|
||
gcse_create_count = 0;
|
||
|
||
alloc_hash_table (max_cuid, &expr_hash_table, 0);
|
||
alloc_rd_mem (last_basic_block, max_cuid);
|
||
compute_hash_table (&expr_hash_table);
|
||
if (gcse_file)
|
||
dump_hash_table (gcse_file, "Expression", &expr_hash_table);
|
||
|
||
if (expr_hash_table.n_elems > 0)
|
||
{
|
||
compute_kill_rd ();
|
||
compute_rd ();
|
||
alloc_avail_expr_mem (last_basic_block, expr_hash_table.n_elems);
|
||
compute_ae_gen (&expr_hash_table);
|
||
compute_ae_kill (ae_gen, ae_kill, &expr_hash_table);
|
||
compute_available (ae_gen, ae_kill, ae_out, ae_in);
|
||
changed = classic_gcse ();
|
||
free_avail_expr_mem ();
|
||
}
|
||
|
||
free_rd_mem ();
|
||
free_hash_table (&expr_hash_table);
|
||
|
||
if (gcse_file)
|
||
{
|
||
fprintf (gcse_file, "\n");
|
||
fprintf (gcse_file, "GCSE of %s, pass %d: %d bytes needed, %d substs,",
|
||
current_function_name (), pass, bytes_used, gcse_subst_count);
|
||
fprintf (gcse_file, "%d insns created\n", gcse_create_count);
|
||
}
|
||
|
||
return changed;
|
||
}
|
||
|
||
/* Compute copy/constant propagation working variables. */
|
||
|
||
/* Local properties of assignments. */
|
||
static sbitmap *cprop_pavloc;
|
||
static sbitmap *cprop_absaltered;
|
||
|
||
/* Global properties of assignments (computed from the local properties). */
|
||
static sbitmap *cprop_avin;
|
||
static sbitmap *cprop_avout;
|
||
|
||
/* Allocate vars used for copy/const propagation. N_BLOCKS is the number of
|
||
basic blocks. N_SETS is the number of sets. */
|
||
|
||
static void
|
||
alloc_cprop_mem (int n_blocks, int n_sets)
|
||
{
|
||
cprop_pavloc = sbitmap_vector_alloc (n_blocks, n_sets);
|
||
cprop_absaltered = sbitmap_vector_alloc (n_blocks, n_sets);
|
||
|
||
cprop_avin = sbitmap_vector_alloc (n_blocks, n_sets);
|
||
cprop_avout = sbitmap_vector_alloc (n_blocks, n_sets);
|
||
}
|
||
|
||
/* Free vars used by copy/const propagation. */
|
||
|
||
static void
|
||
free_cprop_mem (void)
|
||
{
|
||
sbitmap_vector_free (cprop_pavloc);
|
||
sbitmap_vector_free (cprop_absaltered);
|
||
sbitmap_vector_free (cprop_avin);
|
||
sbitmap_vector_free (cprop_avout);
|
||
}
|
||
|
||
/* For each block, compute whether X is transparent. X is either an
|
||
expression or an assignment [though we don't care which, for this context
|
||
an assignment is treated as an expression]. For each block where an
|
||
element of X is modified, set (SET_P == 1) or reset (SET_P == 0) the INDX
|
||
bit in BMAP. */
|
||
|
||
static void
|
||
compute_transp (rtx x, int indx, sbitmap *bmap, int set_p)
|
||
{
|
||
int i, j;
|
||
basic_block bb;
|
||
enum rtx_code code;
|
||
reg_set *r;
|
||
const char *fmt;
|
||
|
||
/* repeat is used to turn tail-recursion into iteration since GCC
|
||
can't do it when there's no return value. */
|
||
repeat:
|
||
|
||
if (x == 0)
|
||
return;
|
||
|
||
code = GET_CODE (x);
|
||
switch (code)
|
||
{
|
||
case REG:
|
||
if (set_p)
|
||
{
|
||
if (REGNO (x) < FIRST_PSEUDO_REGISTER)
|
||
{
|
||
FOR_EACH_BB (bb)
|
||
if (TEST_BIT (reg_set_in_block[bb->index], REGNO (x)))
|
||
SET_BIT (bmap[bb->index], indx);
|
||
}
|
||
else
|
||
{
|
||
for (r = reg_set_table[REGNO (x)]; r != NULL; r = r->next)
|
||
SET_BIT (bmap[BLOCK_NUM (r->insn)], indx);
|
||
}
|
||
}
|
||
else
|
||
{
|
||
if (REGNO (x) < FIRST_PSEUDO_REGISTER)
|
||
{
|
||
FOR_EACH_BB (bb)
|
||
if (TEST_BIT (reg_set_in_block[bb->index], REGNO (x)))
|
||
RESET_BIT (bmap[bb->index], indx);
|
||
}
|
||
else
|
||
{
|
||
for (r = reg_set_table[REGNO (x)]; r != NULL; r = r->next)
|
||
RESET_BIT (bmap[BLOCK_NUM (r->insn)], indx);
|
||
}
|
||
}
|
||
|
||
return;
|
||
|
||
case MEM:
|
||
FOR_EACH_BB (bb)
|
||
{
|
||
rtx list_entry = canon_modify_mem_list[bb->index];
|
||
|
||
while (list_entry)
|
||
{
|
||
rtx dest, dest_addr;
|
||
|
||
if (GET_CODE (XEXP (list_entry, 0)) == CALL_INSN)
|
||
{
|
||
if (set_p)
|
||
SET_BIT (bmap[bb->index], indx);
|
||
else
|
||
RESET_BIT (bmap[bb->index], indx);
|
||
break;
|
||
}
|
||
/* LIST_ENTRY must be an INSN of some kind that sets memory.
|
||
Examine each hunk of memory that is modified. */
|
||
|
||
dest = XEXP (list_entry, 0);
|
||
list_entry = XEXP (list_entry, 1);
|
||
dest_addr = XEXP (list_entry, 0);
|
||
|
||
if (canon_true_dependence (dest, GET_MODE (dest), dest_addr,
|
||
x, rtx_addr_varies_p))
|
||
{
|
||
if (set_p)
|
||
SET_BIT (bmap[bb->index], indx);
|
||
else
|
||
RESET_BIT (bmap[bb->index], indx);
|
||
break;
|
||
}
|
||
list_entry = XEXP (list_entry, 1);
|
||
}
|
||
}
|
||
|
||
x = XEXP (x, 0);
|
||
goto repeat;
|
||
|
||
case PC:
|
||
case CC0: /*FIXME*/
|
||
case CONST:
|
||
case CONST_INT:
|
||
case CONST_DOUBLE:
|
||
case CONST_VECTOR:
|
||
case SYMBOL_REF:
|
||
case LABEL_REF:
|
||
case ADDR_VEC:
|
||
case ADDR_DIFF_VEC:
|
||
return;
|
||
|
||
default:
|
||
break;
|
||
}
|
||
|
||
for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
|
||
{
|
||
if (fmt[i] == 'e')
|
||
{
|
||
/* If we are about to do the last recursive call
|
||
needed at this level, change it into iteration.
|
||
This function is called enough to be worth it. */
|
||
if (i == 0)
|
||
{
|
||
x = XEXP (x, i);
|
||
goto repeat;
|
||
}
|
||
|
||
compute_transp (XEXP (x, i), indx, bmap, set_p);
|
||
}
|
||
else if (fmt[i] == 'E')
|
||
for (j = 0; j < XVECLEN (x, i); j++)
|
||
compute_transp (XVECEXP (x, i, j), indx, bmap, set_p);
|
||
}
|
||
}
|
||
|
||
/* Top level routine to do the dataflow analysis needed by copy/const
|
||
propagation. */
|
||
|
||
static void
|
||
compute_cprop_data (void)
|
||
{
|
||
compute_local_properties (cprop_absaltered, cprop_pavloc, NULL, &set_hash_table);
|
||
compute_available (cprop_pavloc, cprop_absaltered,
|
||
cprop_avout, cprop_avin);
|
||
}
|
||
|
||
/* Copy/constant propagation. */
|
||
|
||
/* Maximum number of register uses in an insn that we handle. */
|
||
#define MAX_USES 8
|
||
|
||
/* Table of uses found in an insn.
|
||
Allocated statically to avoid alloc/free complexity and overhead. */
|
||
static struct reg_use reg_use_table[MAX_USES];
|
||
|
||
/* Index into `reg_use_table' while building it. */
|
||
static int reg_use_count;
|
||
|
||
/* Set up a list of register numbers used in INSN. The found uses are stored
|
||
in `reg_use_table'. `reg_use_count' is initialized to zero before entry,
|
||
and contains the number of uses in the table upon exit.
|
||
|
||
??? If a register appears multiple times we will record it multiple times.
|
||
This doesn't hurt anything but it will slow things down. */
|
||
|
||
static void
|
||
find_used_regs (rtx *xptr, void *data ATTRIBUTE_UNUSED)
|
||
{
|
||
int i, j;
|
||
enum rtx_code code;
|
||
const char *fmt;
|
||
rtx x = *xptr;
|
||
|
||
/* repeat is used to turn tail-recursion into iteration since GCC
|
||
can't do it when there's no return value. */
|
||
repeat:
|
||
if (x == 0)
|
||
return;
|
||
|
||
code = GET_CODE (x);
|
||
if (REG_P (x))
|
||
{
|
||
if (reg_use_count == MAX_USES)
|
||
return;
|
||
|
||
reg_use_table[reg_use_count].reg_rtx = x;
|
||
reg_use_count++;
|
||
}
|
||
|
||
/* Recursively scan the operands of this expression. */
|
||
|
||
for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
|
||
{
|
||
if (fmt[i] == 'e')
|
||
{
|
||
/* If we are about to do the last recursive call
|
||
needed at this level, change it into iteration.
|
||
This function is called enough to be worth it. */
|
||
if (i == 0)
|
||
{
|
||
x = XEXP (x, 0);
|
||
goto repeat;
|
||
}
|
||
|
||
find_used_regs (&XEXP (x, i), data);
|
||
}
|
||
else if (fmt[i] == 'E')
|
||
for (j = 0; j < XVECLEN (x, i); j++)
|
||
find_used_regs (&XVECEXP (x, i, j), data);
|
||
}
|
||
}
|
||
|
||
/* Try to replace all non-SET_DEST occurrences of FROM in INSN with TO.
|
||
Returns nonzero is successful. */
|
||
|
||
static int
|
||
try_replace_reg (rtx from, rtx to, rtx insn)
|
||
{
|
||
rtx note = find_reg_equal_equiv_note (insn);
|
||
rtx src = 0;
|
||
int success = 0;
|
||
rtx set = single_set (insn);
|
||
|
||
validate_replace_src_group (from, to, insn);
|
||
if (num_changes_pending () && apply_change_group ())
|
||
success = 1;
|
||
|
||
/* Try to simplify SET_SRC if we have substituted a constant. */
|
||
if (success && set && CONSTANT_P (to))
|
||
{
|
||
src = simplify_rtx (SET_SRC (set));
|
||
|
||
if (src)
|
||
validate_change (insn, &SET_SRC (set), src, 0);
|
||
}
|
||
|
||
/* If there is already a NOTE, update the expression in it with our
|
||
replacement. */
|
||
if (note != 0)
|
||
XEXP (note, 0) = simplify_replace_rtx (XEXP (note, 0), from, to);
|
||
|
||
if (!success && set && reg_mentioned_p (from, SET_SRC (set)))
|
||
{
|
||
/* If above failed and this is a single set, try to simplify the source of
|
||
the set given our substitution. We could perhaps try this for multiple
|
||
SETs, but it probably won't buy us anything. */
|
||
src = simplify_replace_rtx (SET_SRC (set), from, to);
|
||
|
||
if (!rtx_equal_p (src, SET_SRC (set))
|
||
&& validate_change (insn, &SET_SRC (set), src, 0))
|
||
success = 1;
|
||
|
||
/* If we've failed to do replacement, have a single SET, don't already
|
||
have a note, and have no special SET, add a REG_EQUAL note to not
|
||
lose information. */
|
||
if (!success && note == 0 && set != 0
|
||
&& GET_CODE (XEXP (set, 0)) != ZERO_EXTRACT
|
||
&& GET_CODE (XEXP (set, 0)) != SIGN_EXTRACT)
|
||
note = set_unique_reg_note (insn, REG_EQUAL, copy_rtx (src));
|
||
}
|
||
|
||
/* REG_EQUAL may get simplified into register.
|
||
We don't allow that. Remove that note. This code ought
|
||
not to happen, because previous code ought to synthesize
|
||
reg-reg move, but be on the safe side. */
|
||
if (note && REG_P (XEXP (note, 0)))
|
||
remove_note (insn, note);
|
||
|
||
return success;
|
||
}
|
||
|
||
/* Find a set of REGNOs that are available on entry to INSN's block. Returns
|
||
NULL no such set is found. */
|
||
|
||
static struct expr *
|
||
find_avail_set (int regno, rtx insn)
|
||
{
|
||
/* SET1 contains the last set found that can be returned to the caller for
|
||
use in a substitution. */
|
||
struct expr *set1 = 0;
|
||
|
||
/* Loops are not possible here. To get a loop we would need two sets
|
||
available at the start of the block containing INSN. ie we would
|
||
need two sets like this available at the start of the block:
|
||
|
||
(set (reg X) (reg Y))
|
||
(set (reg Y) (reg X))
|
||
|
||
This can not happen since the set of (reg Y) would have killed the
|
||
set of (reg X) making it unavailable at the start of this block. */
|
||
while (1)
|
||
{
|
||
rtx src;
|
||
struct expr *set = lookup_set (regno, &set_hash_table);
|
||
|
||
/* Find a set that is available at the start of the block
|
||
which contains INSN. */
|
||
while (set)
|
||
{
|
||
if (TEST_BIT (cprop_avin[BLOCK_NUM (insn)], set->bitmap_index))
|
||
break;
|
||
set = next_set (regno, set);
|
||
}
|
||
|
||
/* If no available set was found we've reached the end of the
|
||
(possibly empty) copy chain. */
|
||
if (set == 0)
|
||
break;
|
||
|
||
if (GET_CODE (set->expr) != SET)
|
||
abort ();
|
||
|
||
src = SET_SRC (set->expr);
|
||
|
||
/* We know the set is available.
|
||
Now check that SRC is ANTLOC (i.e. none of the source operands
|
||
have changed since the start of the block).
|
||
|
||
If the source operand changed, we may still use it for the next
|
||
iteration of this loop, but we may not use it for substitutions. */
|
||
|
||
if (gcse_constant_p (src) || oprs_not_set_p (src, insn))
|
||
set1 = set;
|
||
|
||
/* If the source of the set is anything except a register, then
|
||
we have reached the end of the copy chain. */
|
||
if (GET_CODE (src) != REG)
|
||
break;
|
||
|
||
/* Follow the copy chain, ie start another iteration of the loop
|
||
and see if we have an available copy into SRC. */
|
||
regno = REGNO (src);
|
||
}
|
||
|
||
/* SET1 holds the last set that was available and anticipatable at
|
||
INSN. */
|
||
return set1;
|
||
}
|
||
|
||
/* Subroutine of cprop_insn that tries to propagate constants into
|
||
JUMP_INSNS. JUMP must be a conditional jump. If SETCC is non-NULL
|
||
it is the instruction that immediately precedes JUMP, and must be a
|
||
single SET of a register. FROM is what we will try to replace,
|
||
SRC is the constant we will try to substitute for it. Returns nonzero
|
||
if a change was made. */
|
||
|
||
static int
|
||
cprop_jump (basic_block bb, rtx setcc, rtx jump, rtx from, rtx src)
|
||
{
|
||
rtx new, set_src, note_src;
|
||
rtx set = pc_set (jump);
|
||
rtx note = find_reg_equal_equiv_note (jump);
|
||
|
||
if (note)
|
||
{
|
||
note_src = XEXP (note, 0);
|
||
if (GET_CODE (note_src) == EXPR_LIST)
|
||
note_src = NULL_RTX;
|
||
}
|
||
else note_src = NULL_RTX;
|
||
|
||
/* Prefer REG_EQUAL notes except those containing EXPR_LISTs. */
|
||
set_src = note_src ? note_src : SET_SRC (set);
|
||
|
||
/* First substitute the SETCC condition into the JUMP instruction,
|
||
then substitute that given values into this expanded JUMP. */
|
||
if (setcc != NULL_RTX
|
||
&& !modified_between_p (from, setcc, jump)
|
||
&& !modified_between_p (src, setcc, jump))
|
||
{
|
||
rtx setcc_src;
|
||
rtx setcc_set = single_set (setcc);
|
||
rtx setcc_note = find_reg_equal_equiv_note (setcc);
|
||
setcc_src = (setcc_note && GET_CODE (XEXP (setcc_note, 0)) != EXPR_LIST)
|
||
? XEXP (setcc_note, 0) : SET_SRC (setcc_set);
|
||
set_src = simplify_replace_rtx (set_src, SET_DEST (setcc_set),
|
||
setcc_src);
|
||
}
|
||
else
|
||
setcc = NULL_RTX;
|
||
|
||
new = simplify_replace_rtx (set_src, from, src);
|
||
|
||
/* If no simplification can be made, then try the next register. */
|
||
if (rtx_equal_p (new, SET_SRC (set)))
|
||
return 0;
|
||
|
||
/* If this is now a no-op delete it, otherwise this must be a valid insn. */
|
||
if (new == pc_rtx)
|
||
delete_insn (jump);
|
||
else
|
||
{
|
||
/* Ensure the value computed inside the jump insn to be equivalent
|
||
to one computed by setcc. */
|
||
if (setcc && modified_in_p (new, setcc))
|
||
return 0;
|
||
if (! validate_change (jump, &SET_SRC (set), new, 0))
|
||
{
|
||
/* When (some) constants are not valid in a comparison, and there
|
||
are two registers to be replaced by constants before the entire
|
||
comparison can be folded into a constant, we need to keep
|
||
intermediate information in REG_EQUAL notes. For targets with
|
||
separate compare insns, such notes are added by try_replace_reg.
|
||
When we have a combined compare-and-branch instruction, however,
|
||
we need to attach a note to the branch itself to make this
|
||
optimization work. */
|
||
|
||
if (!rtx_equal_p (new, note_src))
|
||
set_unique_reg_note (jump, REG_EQUAL, copy_rtx (new));
|
||
return 0;
|
||
}
|
||
|
||
/* Remove REG_EQUAL note after simplification. */
|
||
if (note_src)
|
||
remove_note (jump, note);
|
||
|
||
/* If this has turned into an unconditional jump,
|
||
then put a barrier after it so that the unreachable
|
||
code will be deleted. */
|
||
if (GET_CODE (SET_SRC (set)) == LABEL_REF)
|
||
emit_barrier_after (jump);
|
||
}
|
||
|
||
#ifdef HAVE_cc0
|
||
/* Delete the cc0 setter. */
|
||
if (setcc != NULL && CC0_P (SET_DEST (single_set (setcc))))
|
||
delete_insn (setcc);
|
||
#endif
|
||
|
||
run_jump_opt_after_gcse = 1;
|
||
|
||
const_prop_count++;
|
||
if (gcse_file != NULL)
|
||
{
|
||
fprintf (gcse_file,
|
||
"CONST-PROP: Replacing reg %d in jump_insn %d with constant ",
|
||
REGNO (from), INSN_UID (jump));
|
||
print_rtl (gcse_file, src);
|
||
fprintf (gcse_file, "\n");
|
||
}
|
||
purge_dead_edges (bb);
|
||
|
||
return 1;
|
||
}
|
||
|
||
static bool
|
||
constprop_register (rtx insn, rtx from, rtx to, int alter_jumps)
|
||
{
|
||
rtx sset;
|
||
|
||
/* Check for reg or cc0 setting instructions followed by
|
||
conditional branch instructions first. */
|
||
if (alter_jumps
|
||
&& (sset = single_set (insn)) != NULL
|
||
&& NEXT_INSN (insn)
|
||
&& any_condjump_p (NEXT_INSN (insn)) && onlyjump_p (NEXT_INSN (insn)))
|
||
{
|
||
rtx dest = SET_DEST (sset);
|
||
if ((REG_P (dest) || CC0_P (dest))
|
||
&& cprop_jump (BLOCK_FOR_INSN (insn), insn, NEXT_INSN (insn), from, to))
|
||
return 1;
|
||
}
|
||
|
||
/* Handle normal insns next. */
|
||
if (GET_CODE (insn) == INSN
|
||
&& try_replace_reg (from, to, insn))
|
||
return 1;
|
||
|
||
/* Try to propagate a CONST_INT into a conditional jump.
|
||
We're pretty specific about what we will handle in this
|
||
code, we can extend this as necessary over time.
|
||
|
||
Right now the insn in question must look like
|
||
(set (pc) (if_then_else ...)) */
|
||
else if (alter_jumps && any_condjump_p (insn) && onlyjump_p (insn))
|
||
return cprop_jump (BLOCK_FOR_INSN (insn), NULL, insn, from, to);
|
||
return 0;
|
||
}
|
||
|
||
/* Perform constant and copy propagation on INSN.
|
||
The result is nonzero if a change was made. */
|
||
|
||
static int
|
||
cprop_insn (rtx insn, int alter_jumps)
|
||
{
|
||
struct reg_use *reg_used;
|
||
int changed = 0;
|
||
rtx note;
|
||
|
||
if (!INSN_P (insn))
|
||
return 0;
|
||
|
||
reg_use_count = 0;
|
||
note_uses (&PATTERN (insn), find_used_regs, NULL);
|
||
|
||
note = find_reg_equal_equiv_note (insn);
|
||
|
||
/* We may win even when propagating constants into notes. */
|
||
if (note)
|
||
find_used_regs (&XEXP (note, 0), NULL);
|
||
|
||
for (reg_used = ®_use_table[0]; reg_use_count > 0;
|
||
reg_used++, reg_use_count--)
|
||
{
|
||
unsigned int regno = REGNO (reg_used->reg_rtx);
|
||
rtx pat, src;
|
||
struct expr *set;
|
||
|
||
/* Ignore registers created by GCSE.
|
||
We do this because ... */
|
||
if (regno >= max_gcse_regno)
|
||
continue;
|
||
|
||
/* If the register has already been set in this block, there's
|
||
nothing we can do. */
|
||
if (! oprs_not_set_p (reg_used->reg_rtx, insn))
|
||
continue;
|
||
|
||
/* Find an assignment that sets reg_used and is available
|
||
at the start of the block. */
|
||
set = find_avail_set (regno, insn);
|
||
if (! set)
|
||
continue;
|
||
|
||
pat = set->expr;
|
||
/* ??? We might be able to handle PARALLELs. Later. */
|
||
if (GET_CODE (pat) != SET)
|
||
abort ();
|
||
|
||
src = SET_SRC (pat);
|
||
|
||
/* Constant propagation. */
|
||
if (gcse_constant_p (src))
|
||
{
|
||
if (constprop_register (insn, reg_used->reg_rtx, src, alter_jumps))
|
||
{
|
||
changed = 1;
|
||
const_prop_count++;
|
||
if (gcse_file != NULL)
|
||
{
|
||
fprintf (gcse_file, "GLOBAL CONST-PROP: Replacing reg %d in ", regno);
|
||
fprintf (gcse_file, "insn %d with constant ", INSN_UID (insn));
|
||
print_rtl (gcse_file, src);
|
||
fprintf (gcse_file, "\n");
|
||
}
|
||
if (INSN_DELETED_P (insn))
|
||
return 1;
|
||
}
|
||
}
|
||
else if (GET_CODE (src) == REG
|
||
&& REGNO (src) >= FIRST_PSEUDO_REGISTER
|
||
&& REGNO (src) != regno)
|
||
{
|
||
if (try_replace_reg (reg_used->reg_rtx, src, insn))
|
||
{
|
||
changed = 1;
|
||
copy_prop_count++;
|
||
if (gcse_file != NULL)
|
||
{
|
||
fprintf (gcse_file, "GLOBAL COPY-PROP: Replacing reg %d in insn %d",
|
||
regno, INSN_UID (insn));
|
||
fprintf (gcse_file, " with reg %d\n", REGNO (src));
|
||
}
|
||
|
||
/* The original insn setting reg_used may or may not now be
|
||
deletable. We leave the deletion to flow. */
|
||
/* FIXME: If it turns out that the insn isn't deletable,
|
||
then we may have unnecessarily extended register lifetimes
|
||
and made things worse. */
|
||
}
|
||
}
|
||
}
|
||
|
||
return changed;
|
||
}
|
||
|
||
/* Like find_used_regs, but avoid recording uses that appear in
|
||
input-output contexts such as zero_extract or pre_dec. This
|
||
restricts the cases we consider to those for which local cprop
|
||
can legitimately make replacements. */
|
||
|
||
static void
|
||
local_cprop_find_used_regs (rtx *xptr, void *data)
|
||
{
|
||
rtx x = *xptr;
|
||
|
||
if (x == 0)
|
||
return;
|
||
|
||
switch (GET_CODE (x))
|
||
{
|
||
case ZERO_EXTRACT:
|
||
case SIGN_EXTRACT:
|
||
case STRICT_LOW_PART:
|
||
return;
|
||
|
||
case PRE_DEC:
|
||
case PRE_INC:
|
||
case POST_DEC:
|
||
case POST_INC:
|
||
case PRE_MODIFY:
|
||
case POST_MODIFY:
|
||
/* Can only legitimately appear this early in the context of
|
||
stack pushes for function arguments, but handle all of the
|
||
codes nonetheless. */
|
||
return;
|
||
|
||
case SUBREG:
|
||
/* Setting a subreg of a register larger than word_mode leaves
|
||
the non-written words unchanged. */
|
||
if (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x))) > BITS_PER_WORD)
|
||
return;
|
||
break;
|
||
|
||
default:
|
||
break;
|
||
}
|
||
|
||
find_used_regs (xptr, data);
|
||
}
|
||
|
||
/* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
|
||
their REG_EQUAL notes need updating. */
|
||
|
||
static bool
|
||
do_local_cprop (rtx x, rtx insn, int alter_jumps, rtx *libcall_sp)
|
||
{
|
||
rtx newreg = NULL, newcnst = NULL;
|
||
|
||
/* Rule out USE instructions and ASM statements as we don't want to
|
||
change the hard registers mentioned. */
|
||
if (GET_CODE (x) == REG
|
||
&& (REGNO (x) >= FIRST_PSEUDO_REGISTER
|
||
|| (GET_CODE (PATTERN (insn)) != USE
|
||
&& asm_noperands (PATTERN (insn)) < 0)))
|
||
{
|
||
cselib_val *val = cselib_lookup (x, GET_MODE (x), 0);
|
||
struct elt_loc_list *l;
|
||
|
||
if (!val)
|
||
return false;
|
||
for (l = val->locs; l; l = l->next)
|
||
{
|
||
rtx this_rtx = l->loc;
|
||
rtx note;
|
||
|
||
/* Don't CSE non-constant values out of libcall blocks. */
|
||
if (l->in_libcall && ! CONSTANT_P (this_rtx))
|
||
continue;
|
||
|
||
if (gcse_constant_p (this_rtx))
|
||
newcnst = this_rtx;
|
||
if (REG_P (this_rtx) && REGNO (this_rtx) >= FIRST_PSEUDO_REGISTER
|
||
/* Don't copy propagate if it has attached REG_EQUIV note.
|
||
At this point this only function parameters should have
|
||
REG_EQUIV notes and if the argument slot is used somewhere
|
||
explicitly, it means address of parameter has been taken,
|
||
so we should not extend the lifetime of the pseudo. */
|
||
&& (!(note = find_reg_note (l->setting_insn, REG_EQUIV, NULL_RTX))
|
||
|| GET_CODE (XEXP (note, 0)) != MEM))
|
||
newreg = this_rtx;
|
||
}
|
||
if (newcnst && constprop_register (insn, x, newcnst, alter_jumps))
|
||
{
|
||
/* If we find a case where we can't fix the retval REG_EQUAL notes
|
||
match the new register, we either have to abandon this replacement
|
||
or fix delete_trivially_dead_insns to preserve the setting insn,
|
||
or make it delete the REG_EUAQL note, and fix up all passes that
|
||
require the REG_EQUAL note there. */
|
||
if (!adjust_libcall_notes (x, newcnst, insn, libcall_sp))
|
||
abort ();
|
||
if (gcse_file != NULL)
|
||
{
|
||
fprintf (gcse_file, "LOCAL CONST-PROP: Replacing reg %d in ",
|
||
REGNO (x));
|
||
fprintf (gcse_file, "insn %d with constant ",
|
||
INSN_UID (insn));
|
||
print_rtl (gcse_file, newcnst);
|
||
fprintf (gcse_file, "\n");
|
||
}
|
||
const_prop_count++;
|
||
return true;
|
||
}
|
||
else if (newreg && newreg != x && try_replace_reg (x, newreg, insn))
|
||
{
|
||
adjust_libcall_notes (x, newreg, insn, libcall_sp);
|
||
if (gcse_file != NULL)
|
||
{
|
||
fprintf (gcse_file,
|
||
"LOCAL COPY-PROP: Replacing reg %d in insn %d",
|
||
REGNO (x), INSN_UID (insn));
|
||
fprintf (gcse_file, " with reg %d\n", REGNO (newreg));
|
||
}
|
||
copy_prop_count++;
|
||
return true;
|
||
}
|
||
}
|
||
return false;
|
||
}
|
||
|
||
/* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
|
||
their REG_EQUAL notes need updating to reflect that OLDREG has been
|
||
replaced with NEWVAL in INSN. Return true if all substitutions could
|
||
be made. */
|
||
static bool
|
||
adjust_libcall_notes (rtx oldreg, rtx newval, rtx insn, rtx *libcall_sp)
|
||
{
|
||
rtx end;
|
||
|
||
while ((end = *libcall_sp++))
|
||
{
|
||
rtx note = find_reg_equal_equiv_note (end);
|
||
|
||
if (! note)
|
||
continue;
|
||
|
||
if (REG_P (newval))
|
||
{
|
||
if (reg_set_between_p (newval, PREV_INSN (insn), end))
|
||
{
|
||
do
|
||
{
|
||
note = find_reg_equal_equiv_note (end);
|
||
if (! note)
|
||
continue;
|
||
if (reg_mentioned_p (newval, XEXP (note, 0)))
|
||
return false;
|
||
}
|
||
while ((end = *libcall_sp++));
|
||
return true;
|
||
}
|
||
}
|
||
XEXP (note, 0) = simplify_replace_rtx (XEXP (note, 0), oldreg, newval);
|
||
insn = end;
|
||
}
|
||
return true;
|
||
}
|
||
|
||
#define MAX_NESTED_LIBCALLS 9
|
||
|
||
static void
|
||
local_cprop_pass (int alter_jumps)
|
||
{
|
||
rtx insn;
|
||
struct reg_use *reg_used;
|
||
rtx libcall_stack[MAX_NESTED_LIBCALLS + 1], *libcall_sp;
|
||
bool changed = false;
|
||
|
||
cselib_init ();
|
||
libcall_sp = &libcall_stack[MAX_NESTED_LIBCALLS];
|
||
*libcall_sp = 0;
|
||
for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
|
||
{
|
||
if (INSN_P (insn))
|
||
{
|
||
rtx note = find_reg_note (insn, REG_LIBCALL, NULL_RTX);
|
||
|
||
if (note)
|
||
{
|
||
if (libcall_sp == libcall_stack)
|
||
abort ();
|
||
*--libcall_sp = XEXP (note, 0);
|
||
}
|
||
note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
|
||
if (note)
|
||
libcall_sp++;
|
||
note = find_reg_equal_equiv_note (insn);
|
||
do
|
||
{
|
||
reg_use_count = 0;
|
||
note_uses (&PATTERN (insn), local_cprop_find_used_regs, NULL);
|
||
if (note)
|
||
local_cprop_find_used_regs (&XEXP (note, 0), NULL);
|
||
|
||
for (reg_used = ®_use_table[0]; reg_use_count > 0;
|
||
reg_used++, reg_use_count--)
|
||
if (do_local_cprop (reg_used->reg_rtx, insn, alter_jumps,
|
||
libcall_sp))
|
||
{
|
||
changed = true;
|
||
break;
|
||
}
|
||
if (INSN_DELETED_P (insn))
|
||
break;
|
||
}
|
||
while (reg_use_count);
|
||
}
|
||
cselib_process_insn (insn);
|
||
}
|
||
cselib_finish ();
|
||
/* Global analysis may get into infinite loops for unreachable blocks. */
|
||
if (changed && alter_jumps)
|
||
{
|
||
delete_unreachable_blocks ();
|
||
free_reg_set_mem ();
|
||
alloc_reg_set_mem (max_reg_num ());
|
||
compute_sets (get_insns ());
|
||
}
|
||
}
|
||
|
||
/* Forward propagate copies. This includes copies and constants. Return
|
||
nonzero if a change was made. */
|
||
|
||
static int
|
||
cprop (int alter_jumps)
|
||
{
|
||
int changed;
|
||
basic_block bb;
|
||
rtx insn;
|
||
|
||
/* Note we start at block 1. */
|
||
if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
|
||
{
|
||
if (gcse_file != NULL)
|
||
fprintf (gcse_file, "\n");
|
||
return 0;
|
||
}
|
||
|
||
changed = 0;
|
||
FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb, EXIT_BLOCK_PTR, next_bb)
|
||
{
|
||
/* Reset tables used to keep track of what's still valid [since the
|
||
start of the block]. */
|
||
reset_opr_set_tables ();
|
||
|
||
for (insn = BB_HEAD (bb);
|
||
insn != NULL && insn != NEXT_INSN (BB_END (bb));
|
||
insn = NEXT_INSN (insn))
|
||
if (INSN_P (insn))
|
||
{
|
||
changed |= cprop_insn (insn, alter_jumps);
|
||
|
||
/* Keep track of everything modified by this insn. */
|
||
/* ??? Need to be careful w.r.t. mods done to INSN. Don't
|
||
call mark_oprs_set if we turned the insn into a NOTE. */
|
||
if (GET_CODE (insn) != NOTE)
|
||
mark_oprs_set (insn);
|
||
}
|
||
}
|
||
|
||
if (gcse_file != NULL)
|
||
fprintf (gcse_file, "\n");
|
||
|
||
return changed;
|
||
}
|
||
|
||
/* Similar to get_condition, only the resulting condition must be
|
||
valid at JUMP, instead of at EARLIEST.
|
||
|
||
This differs from noce_get_condition in ifcvt.c in that we prefer not to
|
||
settle for the condition variable in the jump instruction being integral.
|
||
We prefer to be able to record the value of a user variable, rather than
|
||
the value of a temporary used in a condition. This could be solved by
|
||
recording the value of *every* register scaned by canonicalize_condition,
|
||
but this would require some code reorganization. */
|
||
|
||
rtx
|
||
fis_get_condition (rtx jump)
|
||
{
|
||
rtx cond, set, tmp, insn, earliest;
|
||
bool reverse;
|
||
|
||
if (! any_condjump_p (jump))
|
||
return NULL_RTX;
|
||
|
||
set = pc_set (jump);
|
||
cond = XEXP (SET_SRC (set), 0);
|
||
|
||
/* If this branches to JUMP_LABEL when the condition is false,
|
||
reverse the condition. */
|
||
reverse = (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
|
||
&& XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump));
|
||
|
||
/* Use canonicalize_condition to do the dirty work of manipulating
|
||
MODE_CC values and COMPARE rtx codes. */
|
||
tmp = canonicalize_condition (jump, cond, reverse, &earliest, NULL_RTX,
|
||
false);
|
||
if (!tmp)
|
||
return NULL_RTX;
|
||
|
||
/* Verify that the given condition is valid at JUMP by virtue of not
|
||
having been modified since EARLIEST. */
|
||
for (insn = earliest; insn != jump; insn = NEXT_INSN (insn))
|
||
if (INSN_P (insn) && modified_in_p (tmp, insn))
|
||
break;
|
||
if (insn == jump)
|
||
return tmp;
|
||
|
||
/* The condition was modified. See if we can get a partial result
|
||
that doesn't follow all the reversals. Perhaps combine can fold
|
||
them together later. */
|
||
tmp = XEXP (tmp, 0);
|
||
if (!REG_P (tmp) || GET_MODE_CLASS (GET_MODE (tmp)) != MODE_INT)
|
||
return NULL_RTX;
|
||
tmp = canonicalize_condition (jump, cond, reverse, &earliest, tmp,
|
||
false);
|
||
if (!tmp)
|
||
return NULL_RTX;
|
||
|
||
/* For sanity's sake, re-validate the new result. */
|
||
for (insn = earliest; insn != jump; insn = NEXT_INSN (insn))
|
||
if (INSN_P (insn) && modified_in_p (tmp, insn))
|
||
return NULL_RTX;
|
||
|
||
return tmp;
|
||
}
|
||
|
||
/* Check the comparison COND to see if we can safely form an implicit set from
|
||
it. COND is either an EQ or NE comparison. */
|
||
|
||
static bool
|
||
implicit_set_cond_p (rtx cond)
|
||
{
|
||
enum machine_mode mode = GET_MODE (XEXP (cond, 0));
|
||
rtx cst = XEXP (cond, 1);
|
||
|
||
/* We can't perform this optimization if either operand might be or might
|
||
contain a signed zero. */
|
||
if (HONOR_SIGNED_ZEROS (mode))
|
||
{
|
||
/* It is sufficient to check if CST is or contains a zero. We must
|
||
handle float, complex, and vector. If any subpart is a zero, then
|
||
the optimization can't be performed. */
|
||
/* ??? The complex and vector checks are not implemented yet. We just
|
||
always return zero for them. */
|
||
if (GET_CODE (cst) == CONST_DOUBLE)
|
||
{
|
||
REAL_VALUE_TYPE d;
|
||
REAL_VALUE_FROM_CONST_DOUBLE (d, cst);
|
||
if (REAL_VALUES_EQUAL (d, dconst0))
|
||
return 0;
|
||
}
|
||
else
|
||
return 0;
|
||
}
|
||
|
||
return gcse_constant_p (cst);
|
||
}
|
||
|
||
/* Find the implicit sets of a function. An "implicit set" is a constraint
|
||
on the value of a variable, implied by a conditional jump. For example,
|
||
following "if (x == 2)", the then branch may be optimized as though the
|
||
conditional performed an "explicit set", in this example, "x = 2". This
|
||
function records the set patterns that are implicit at the start of each
|
||
basic block. */
|
||
|
||
static void
|
||
find_implicit_sets (void)
|
||
{
|
||
basic_block bb, dest;
|
||
unsigned int count;
|
||
rtx cond, new;
|
||
|
||
count = 0;
|
||
FOR_EACH_BB (bb)
|
||
/* Check for more than one successor. */
|
||
if (bb->succ && bb->succ->succ_next)
|
||
{
|
||
cond = fis_get_condition (BB_END (bb));
|
||
|
||
if (cond
|
||
&& (GET_CODE (cond) == EQ || GET_CODE (cond) == NE)
|
||
&& GET_CODE (XEXP (cond, 0)) == REG
|
||
&& REGNO (XEXP (cond, 0)) >= FIRST_PSEUDO_REGISTER
|
||
&& implicit_set_cond_p (cond))
|
||
{
|
||
dest = GET_CODE (cond) == EQ ? BRANCH_EDGE (bb)->dest
|
||
: FALLTHRU_EDGE (bb)->dest;
|
||
|
||
if (dest && ! dest->pred->pred_next
|
||
&& dest != EXIT_BLOCK_PTR)
|
||
{
|
||
new = gen_rtx_SET (VOIDmode, XEXP (cond, 0),
|
||
XEXP (cond, 1));
|
||
implicit_sets[dest->index] = new;
|
||
if (gcse_file)
|
||
{
|
||
fprintf(gcse_file, "Implicit set of reg %d in ",
|
||
REGNO (XEXP (cond, 0)));
|
||
fprintf(gcse_file, "basic block %d\n", dest->index);
|
||
}
|
||
count++;
|
||
}
|
||
}
|
||
}
|
||
|
||
if (gcse_file)
|
||
fprintf (gcse_file, "Found %d implicit sets\n", count);
|
||
}
|
||
|
||
/* Perform one copy/constant propagation pass.
|
||
PASS is the pass count. If CPROP_JUMPS is true, perform constant
|
||
propagation into conditional jumps. If BYPASS_JUMPS is true,
|
||
perform conditional jump bypassing optimizations. */
|
||
|
||
static int
|
||
one_cprop_pass (int pass, int cprop_jumps, int bypass_jumps)
|
||
{
|
||
int changed = 0;
|
||
|
||
const_prop_count = 0;
|
||
copy_prop_count = 0;
|
||
|
||
local_cprop_pass (cprop_jumps);
|
||
|
||
/* Determine implicit sets. */
|
||
implicit_sets = xcalloc (last_basic_block, sizeof (rtx));
|
||
find_implicit_sets ();
|
||
|
||
alloc_hash_table (max_cuid, &set_hash_table, 1);
|
||
compute_hash_table (&set_hash_table);
|
||
|
||
/* Free implicit_sets before peak usage. */
|
||
free (implicit_sets);
|
||
implicit_sets = NULL;
|
||
|
||
if (gcse_file)
|
||
dump_hash_table (gcse_file, "SET", &set_hash_table);
|
||
if (set_hash_table.n_elems > 0)
|
||
{
|
||
alloc_cprop_mem (last_basic_block, set_hash_table.n_elems);
|
||
compute_cprop_data ();
|
||
changed = cprop (cprop_jumps);
|
||
if (bypass_jumps)
|
||
changed |= bypass_conditional_jumps ();
|
||
free_cprop_mem ();
|
||
}
|
||
|
||
free_hash_table (&set_hash_table);
|
||
|
||
if (gcse_file)
|
||
{
|
||
fprintf (gcse_file, "CPROP of %s, pass %d: %d bytes needed, ",
|
||
current_function_name (), pass, bytes_used);
|
||
fprintf (gcse_file, "%d const props, %d copy props\n\n",
|
||
const_prop_count, copy_prop_count);
|
||
}
|
||
/* Global analysis may get into infinite loops for unreachable blocks. */
|
||
if (changed && cprop_jumps)
|
||
delete_unreachable_blocks ();
|
||
|
||
return changed;
|
||
}
|
||
|
||
/* Bypass conditional jumps. */
|
||
|
||
/* The value of last_basic_block at the beginning of the jump_bypass
|
||
pass. The use of redirect_edge_and_branch_force may introduce new
|
||
basic blocks, but the data flow analysis is only valid for basic
|
||
block indices less than bypass_last_basic_block. */
|
||
|
||
static int bypass_last_basic_block;
|
||
|
||
/* Find a set of REGNO to a constant that is available at the end of basic
|
||
block BB. Returns NULL if no such set is found. Based heavily upon
|
||
find_avail_set. */
|
||
|
||
static struct expr *
|
||
find_bypass_set (int regno, int bb)
|
||
{
|
||
struct expr *result = 0;
|
||
|
||
for (;;)
|
||
{
|
||
rtx src;
|
||
struct expr *set = lookup_set (regno, &set_hash_table);
|
||
|
||
while (set)
|
||
{
|
||
if (TEST_BIT (cprop_avout[bb], set->bitmap_index))
|
||
break;
|
||
set = next_set (regno, set);
|
||
}
|
||
|
||
if (set == 0)
|
||
break;
|
||
|
||
if (GET_CODE (set->expr) != SET)
|
||
abort ();
|
||
|
||
src = SET_SRC (set->expr);
|
||
if (gcse_constant_p (src))
|
||
result = set;
|
||
|
||
if (GET_CODE (src) != REG)
|
||
break;
|
||
|
||
regno = REGNO (src);
|
||
}
|
||
return result;
|
||
}
|
||
|
||
|
||
/* Subroutine of bypass_block that checks whether a pseudo is killed by
|
||
any of the instructions inserted on an edge. Jump bypassing places
|
||
condition code setters on CFG edges using insert_insn_on_edge. This
|
||
function is required to check that our data flow analysis is still
|
||
valid prior to commit_edge_insertions. */
|
||
|
||
static bool
|
||
reg_killed_on_edge (rtx reg, edge e)
|
||
{
|
||
rtx insn;
|
||
|
||
for (insn = e->insns; insn; insn = NEXT_INSN (insn))
|
||
if (INSN_P (insn) && reg_set_p (reg, insn))
|
||
return true;
|
||
|
||
return false;
|
||
}
|
||
|
||
/* Subroutine of bypass_conditional_jumps that attempts to bypass the given
|
||
basic block BB which has more than one predecessor. If not NULL, SETCC
|
||
is the first instruction of BB, which is immediately followed by JUMP_INSN
|
||
JUMP. Otherwise, SETCC is NULL, and JUMP is the first insn of BB.
|
||
Returns nonzero if a change was made.
|
||
|
||
During the jump bypassing pass, we may place copies of SETCC instructions
|
||
on CFG edges. The following routine must be careful to pay attention to
|
||
these inserted insns when performing its transformations. */
|
||
|
||
static int
|
||
bypass_block (basic_block bb, rtx setcc, rtx jump)
|
||
{
|
||
rtx insn, note;
|
||
edge e, enext, edest;
|
||
int i, change;
|
||
int may_be_loop_header;
|
||
|
||
insn = (setcc != NULL) ? setcc : jump;
|
||
|
||
/* Determine set of register uses in INSN. */
|
||
reg_use_count = 0;
|
||
note_uses (&PATTERN (insn), find_used_regs, NULL);
|
||
note = find_reg_equal_equiv_note (insn);
|
||
if (note)
|
||
find_used_regs (&XEXP (note, 0), NULL);
|
||
|
||
may_be_loop_header = false;
|
||
for (e = bb->pred; e; e = e->pred_next)
|
||
if (e->flags & EDGE_DFS_BACK)
|
||
{
|
||
may_be_loop_header = true;
|
||
break;
|
||
}
|
||
|
||
change = 0;
|
||
for (e = bb->pred; e; e = enext)
|
||
{
|
||
enext = e->pred_next;
|
||
if (e->flags & EDGE_COMPLEX)
|
||
continue;
|
||
|
||
/* We can't redirect edges from new basic blocks. */
|
||
if (e->src->index >= bypass_last_basic_block)
|
||
continue;
|
||
|
||
/* The irreducible loops created by redirecting of edges entering the
|
||
loop from outside would decrease effectiveness of some of the following
|
||
optimizations, so prevent this. */
|
||
if (may_be_loop_header
|
||
&& !(e->flags & EDGE_DFS_BACK))
|
||
continue;
|
||
|
||
for (i = 0; i < reg_use_count; i++)
|
||
{
|
||
struct reg_use *reg_used = ®_use_table[i];
|
||
unsigned int regno = REGNO (reg_used->reg_rtx);
|
||
basic_block dest, old_dest;
|
||
struct expr *set;
|
||
rtx src, new;
|
||
|
||
if (regno >= max_gcse_regno)
|
||
continue;
|
||
|
||
set = find_bypass_set (regno, e->src->index);
|
||
|
||
if (! set)
|
||
continue;
|
||
|
||
/* Check the data flow is valid after edge insertions. */
|
||
if (e->insns && reg_killed_on_edge (reg_used->reg_rtx, e))
|
||
continue;
|
||
|
||
src = SET_SRC (pc_set (jump));
|
||
|
||
if (setcc != NULL)
|
||
src = simplify_replace_rtx (src,
|
||
SET_DEST (PATTERN (setcc)),
|
||
SET_SRC (PATTERN (setcc)));
|
||
|
||
new = simplify_replace_rtx (src, reg_used->reg_rtx,
|
||
SET_SRC (set->expr));
|
||
|
||
/* Jump bypassing may have already placed instructions on
|
||
edges of the CFG. We can't bypass an outgoing edge that
|
||
has instructions associated with it, as these insns won't
|
||
get executed if the incoming edge is redirected. */
|
||
|
||
if (new == pc_rtx)
|
||
{
|
||
edest = FALLTHRU_EDGE (bb);
|
||
dest = edest->insns ? NULL : edest->dest;
|
||
}
|
||
else if (GET_CODE (new) == LABEL_REF)
|
||
{
|
||
dest = BLOCK_FOR_INSN (XEXP (new, 0));
|
||
/* Don't bypass edges containing instructions. */
|
||
for (edest = bb->succ; edest; edest = edest->succ_next)
|
||
if (edest->dest == dest && edest->insns)
|
||
{
|
||
dest = NULL;
|
||
break;
|
||
}
|
||
}
|
||
else
|
||
dest = NULL;
|
||
|
||
/* Avoid unification of the edge with other edges from original
|
||
branch. We would end up emitting the instruction on "both"
|
||
edges. */
|
||
|
||
if (dest && setcc && !CC0_P (SET_DEST (PATTERN (setcc))))
|
||
{
|
||
edge e2;
|
||
for (e2 = e->src->succ; e2; e2 = e2->succ_next)
|
||
if (e2->dest == dest)
|
||
break;
|
||
if (e2)
|
||
dest = NULL;
|
||
}
|
||
|
||
old_dest = e->dest;
|
||
if (dest != NULL
|
||
&& dest != old_dest
|
||
&& dest != EXIT_BLOCK_PTR)
|
||
{
|
||
redirect_edge_and_branch_force (e, dest);
|
||
|
||
/* Copy the register setter to the redirected edge.
|
||
Don't copy CC0 setters, as CC0 is dead after jump. */
|
||
if (setcc)
|
||
{
|
||
rtx pat = PATTERN (setcc);
|
||
if (!CC0_P (SET_DEST (pat)))
|
||
insert_insn_on_edge (copy_insn (pat), e);
|
||
}
|
||
|
||
if (gcse_file != NULL)
|
||
{
|
||
fprintf (gcse_file, "JUMP-BYPASS: Proved reg %d in jump_insn %d equals constant ",
|
||
regno, INSN_UID (jump));
|
||
print_rtl (gcse_file, SET_SRC (set->expr));
|
||
fprintf (gcse_file, "\nBypass edge from %d->%d to %d\n",
|
||
e->src->index, old_dest->index, dest->index);
|
||
}
|
||
change = 1;
|
||
break;
|
||
}
|
||
}
|
||
}
|
||
return change;
|
||
}
|
||
|
||
/* Find basic blocks with more than one predecessor that only contain a
|
||
single conditional jump. If the result of the comparison is known at
|
||
compile-time from any incoming edge, redirect that edge to the
|
||
appropriate target. Returns nonzero if a change was made.
|
||
|
||
This function is now mis-named, because we also handle indirect jumps. */
|
||
|
||
static int
|
||
bypass_conditional_jumps (void)
|
||
{
|
||
basic_block bb;
|
||
int changed;
|
||
rtx setcc;
|
||
rtx insn;
|
||
rtx dest;
|
||
|
||
/* Note we start at block 1. */
|
||
if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
|
||
return 0;
|
||
|
||
bypass_last_basic_block = last_basic_block;
|
||
mark_dfs_back_edges ();
|
||
|
||
changed = 0;
|
||
FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb,
|
||
EXIT_BLOCK_PTR, next_bb)
|
||
{
|
||
/* Check for more than one predecessor. */
|
||
if (bb->pred && bb->pred->pred_next)
|
||
{
|
||
setcc = NULL_RTX;
|
||
for (insn = BB_HEAD (bb);
|
||
insn != NULL && insn != NEXT_INSN (BB_END (bb));
|
||
insn = NEXT_INSN (insn))
|
||
if (GET_CODE (insn) == INSN)
|
||
{
|
||
if (setcc)
|
||
break;
|
||
if (GET_CODE (PATTERN (insn)) != SET)
|
||
break;
|
||
|
||
dest = SET_DEST (PATTERN (insn));
|
||
if (REG_P (dest) || CC0_P (dest))
|
||
setcc = insn;
|
||
else
|
||
break;
|
||
}
|
||
else if (GET_CODE (insn) == JUMP_INSN)
|
||
{
|
||
if ((any_condjump_p (insn) || computed_jump_p (insn))
|
||
&& onlyjump_p (insn))
|
||
changed |= bypass_block (bb, setcc, insn);
|
||
break;
|
||
}
|
||
else if (INSN_P (insn))
|
||
break;
|
||
}
|
||
}
|
||
|
||
/* If we bypassed any register setting insns, we inserted a
|
||
copy on the redirected edge. These need to be committed. */
|
||
if (changed)
|
||
commit_edge_insertions();
|
||
|
||
return changed;
|
||
}
|
||
|
||
/* Compute PRE+LCM working variables. */
|
||
|
||
/* Local properties of expressions. */
|
||
/* Nonzero for expressions that are transparent in the block. */
|
||
static sbitmap *transp;
|
||
|
||
/* Nonzero for expressions that are transparent at the end of the block.
|
||
This is only zero for expressions killed by abnormal critical edge
|
||
created by a calls. */
|
||
static sbitmap *transpout;
|
||
|
||
/* Nonzero for expressions that are computed (available) in the block. */
|
||
static sbitmap *comp;
|
||
|
||
/* Nonzero for expressions that are locally anticipatable in the block. */
|
||
static sbitmap *antloc;
|
||
|
||
/* Nonzero for expressions where this block is an optimal computation
|
||
point. */
|
||
static sbitmap *pre_optimal;
|
||
|
||
/* Nonzero for expressions which are redundant in a particular block. */
|
||
static sbitmap *pre_redundant;
|
||
|
||
/* Nonzero for expressions which should be inserted on a specific edge. */
|
||
static sbitmap *pre_insert_map;
|
||
|
||
/* Nonzero for expressions which should be deleted in a specific block. */
|
||
static sbitmap *pre_delete_map;
|
||
|
||
/* Contains the edge_list returned by pre_edge_lcm. */
|
||
static struct edge_list *edge_list;
|
||
|
||
/* Redundant insns. */
|
||
static sbitmap pre_redundant_insns;
|
||
|
||
/* Allocate vars used for PRE analysis. */
|
||
|
||
static void
|
||
alloc_pre_mem (int n_blocks, int n_exprs)
|
||
{
|
||
transp = sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
comp = sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
antloc = sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
|
||
pre_optimal = NULL;
|
||
pre_redundant = NULL;
|
||
pre_insert_map = NULL;
|
||
pre_delete_map = NULL;
|
||
ae_in = NULL;
|
||
ae_out = NULL;
|
||
ae_kill = sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
|
||
/* pre_insert and pre_delete are allocated later. */
|
||
}
|
||
|
||
/* Free vars used for PRE analysis. */
|
||
|
||
static void
|
||
free_pre_mem (void)
|
||
{
|
||
sbitmap_vector_free (transp);
|
||
sbitmap_vector_free (comp);
|
||
|
||
/* ANTLOC and AE_KILL are freed just after pre_lcm finishes. */
|
||
|
||
if (pre_optimal)
|
||
sbitmap_vector_free (pre_optimal);
|
||
if (pre_redundant)
|
||
sbitmap_vector_free (pre_redundant);
|
||
if (pre_insert_map)
|
||
sbitmap_vector_free (pre_insert_map);
|
||
if (pre_delete_map)
|
||
sbitmap_vector_free (pre_delete_map);
|
||
if (ae_in)
|
||
sbitmap_vector_free (ae_in);
|
||
if (ae_out)
|
||
sbitmap_vector_free (ae_out);
|
||
|
||
transp = comp = NULL;
|
||
pre_optimal = pre_redundant = pre_insert_map = pre_delete_map = NULL;
|
||
ae_in = ae_out = NULL;
|
||
}
|
||
|
||
/* Top level routine to do the dataflow analysis needed by PRE. */
|
||
|
||
static void
|
||
compute_pre_data (void)
|
||
{
|
||
sbitmap trapping_expr;
|
||
basic_block bb;
|
||
unsigned int ui;
|
||
|
||
compute_local_properties (transp, comp, antloc, &expr_hash_table);
|
||
sbitmap_vector_zero (ae_kill, last_basic_block);
|
||
|
||
/* Collect expressions which might trap. */
|
||
trapping_expr = sbitmap_alloc (expr_hash_table.n_elems);
|
||
sbitmap_zero (trapping_expr);
|
||
for (ui = 0; ui < expr_hash_table.size; ui++)
|
||
{
|
||
struct expr *e;
|
||
for (e = expr_hash_table.table[ui]; e != NULL; e = e->next_same_hash)
|
||
if (may_trap_p (e->expr))
|
||
SET_BIT (trapping_expr, e->bitmap_index);
|
||
}
|
||
|
||
/* Compute ae_kill for each basic block using:
|
||
|
||
~(TRANSP | COMP)
|
||
|
||
This is significantly faster than compute_ae_kill. */
|
||
|
||
FOR_EACH_BB (bb)
|
||
{
|
||
edge e;
|
||
|
||
/* If the current block is the destination of an abnormal edge, we
|
||
kill all trapping expressions because we won't be able to properly
|
||
place the instruction on the edge. So make them neither
|
||
anticipatable nor transparent. This is fairly conservative. */
|
||
for (e = bb->pred; e ; e = e->pred_next)
|
||
if (e->flags & EDGE_ABNORMAL)
|
||
{
|
||
sbitmap_difference (antloc[bb->index], antloc[bb->index], trapping_expr);
|
||
sbitmap_difference (transp[bb->index], transp[bb->index], trapping_expr);
|
||
break;
|
||
}
|
||
|
||
sbitmap_a_or_b (ae_kill[bb->index], transp[bb->index], comp[bb->index]);
|
||
sbitmap_not (ae_kill[bb->index], ae_kill[bb->index]);
|
||
}
|
||
|
||
edge_list = pre_edge_lcm (gcse_file, expr_hash_table.n_elems, transp, comp, antloc,
|
||
ae_kill, &pre_insert_map, &pre_delete_map);
|
||
sbitmap_vector_free (antloc);
|
||
antloc = NULL;
|
||
sbitmap_vector_free (ae_kill);
|
||
ae_kill = NULL;
|
||
sbitmap_free (trapping_expr);
|
||
}
|
||
|
||
/* PRE utilities */
|
||
|
||
/* Return nonzero if an occurrence of expression EXPR in OCCR_BB would reach
|
||
block BB.
|
||
|
||
VISITED is a pointer to a working buffer for tracking which BB's have
|
||
been visited. It is NULL for the top-level call.
|
||
|
||
We treat reaching expressions that go through blocks containing the same
|
||
reaching expression as "not reaching". E.g. if EXPR is generated in blocks
|
||
2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
|
||
2 as not reaching. The intent is to improve the probability of finding
|
||
only one reaching expression and to reduce register lifetimes by picking
|
||
the closest such expression. */
|
||
|
||
static int
|
||
pre_expr_reaches_here_p_work (basic_block occr_bb, struct expr *expr, basic_block bb, char *visited)
|
||
{
|
||
edge pred;
|
||
|
||
for (pred = bb->pred; pred != NULL; pred = pred->pred_next)
|
||
{
|
||
basic_block pred_bb = pred->src;
|
||
|
||
if (pred->src == ENTRY_BLOCK_PTR
|
||
/* Has predecessor has already been visited? */
|
||
|| visited[pred_bb->index])
|
||
;/* Nothing to do. */
|
||
|
||
/* Does this predecessor generate this expression? */
|
||
else if (TEST_BIT (comp[pred_bb->index], expr->bitmap_index))
|
||
{
|
||
/* Is this the occurrence we're looking for?
|
||
Note that there's only one generating occurrence per block
|
||
so we just need to check the block number. */
|
||
if (occr_bb == pred_bb)
|
||
return 1;
|
||
|
||
visited[pred_bb->index] = 1;
|
||
}
|
||
/* Ignore this predecessor if it kills the expression. */
|
||
else if (! TEST_BIT (transp[pred_bb->index], expr->bitmap_index))
|
||
visited[pred_bb->index] = 1;
|
||
|
||
/* Neither gen nor kill. */
|
||
else
|
||
{
|
||
visited[pred_bb->index] = 1;
|
||
if (pre_expr_reaches_here_p_work (occr_bb, expr, pred_bb, visited))
|
||
return 1;
|
||
}
|
||
}
|
||
|
||
/* All paths have been checked. */
|
||
return 0;
|
||
}
|
||
|
||
/* The wrapper for pre_expr_reaches_here_work that ensures that any
|
||
memory allocated for that function is returned. */
|
||
|
||
static int
|
||
pre_expr_reaches_here_p (basic_block occr_bb, struct expr *expr, basic_block bb)
|
||
{
|
||
int rval;
|
||
char *visited = xcalloc (last_basic_block, 1);
|
||
|
||
rval = pre_expr_reaches_here_p_work (occr_bb, expr, bb, visited);
|
||
|
||
free (visited);
|
||
return rval;
|
||
}
|
||
|
||
|
||
/* Given an expr, generate RTL which we can insert at the end of a BB,
|
||
or on an edge. Set the block number of any insns generated to
|
||
the value of BB. */
|
||
|
||
static rtx
|
||
process_insert_insn (struct expr *expr)
|
||
{
|
||
rtx reg = expr->reaching_reg;
|
||
rtx exp = copy_rtx (expr->expr);
|
||
rtx pat;
|
||
|
||
start_sequence ();
|
||
|
||
/* If the expression is something that's an operand, like a constant,
|
||
just copy it to a register. */
|
||
if (general_operand (exp, GET_MODE (reg)))
|
||
emit_move_insn (reg, exp);
|
||
|
||
/* Otherwise, make a new insn to compute this expression and make sure the
|
||
insn will be recognized (this also adds any needed CLOBBERs). Copy the
|
||
expression to make sure we don't have any sharing issues. */
|
||
else if (insn_invalid_p (emit_insn (gen_rtx_SET (VOIDmode, reg, exp))))
|
||
abort ();
|
||
|
||
pat = get_insns ();
|
||
end_sequence ();
|
||
|
||
return pat;
|
||
}
|
||
|
||
/* Add EXPR to the end of basic block BB.
|
||
|
||
This is used by both the PRE and code hoisting.
|
||
|
||
For PRE, we want to verify that the expr is either transparent
|
||
or locally anticipatable in the target block. This check makes
|
||
no sense for code hoisting. */
|
||
|
||
static void
|
||
insert_insn_end_bb (struct expr *expr, basic_block bb, int pre)
|
||
{
|
||
rtx insn = BB_END (bb);
|
||
rtx new_insn;
|
||
rtx reg = expr->reaching_reg;
|
||
int regno = REGNO (reg);
|
||
rtx pat, pat_end;
|
||
|
||
pat = process_insert_insn (expr);
|
||
if (pat == NULL_RTX || ! INSN_P (pat))
|
||
abort ();
|
||
|
||
pat_end = pat;
|
||
while (NEXT_INSN (pat_end) != NULL_RTX)
|
||
pat_end = NEXT_INSN (pat_end);
|
||
|
||
/* If the last insn is a jump, insert EXPR in front [taking care to
|
||
handle cc0, etc. properly]. Similarly we need to care trapping
|
||
instructions in presence of non-call exceptions. */
|
||
|
||
if (GET_CODE (insn) == JUMP_INSN
|
||
|| (GET_CODE (insn) == INSN
|
||
&& (bb->succ->succ_next || (bb->succ->flags & EDGE_ABNORMAL))))
|
||
{
|
||
#ifdef HAVE_cc0
|
||
rtx note;
|
||
#endif
|
||
/* It should always be the case that we can put these instructions
|
||
anywhere in the basic block with performing PRE optimizations.
|
||
Check this. */
|
||
if (GET_CODE (insn) == INSN && pre
|
||
&& !TEST_BIT (antloc[bb->index], expr->bitmap_index)
|
||
&& !TEST_BIT (transp[bb->index], expr->bitmap_index))
|
||
abort ();
|
||
|
||
/* If this is a jump table, then we can't insert stuff here. Since
|
||
we know the previous real insn must be the tablejump, we insert
|
||
the new instruction just before the tablejump. */
|
||
if (GET_CODE (PATTERN (insn)) == ADDR_VEC
|
||
|| GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
|
||
insn = prev_real_insn (insn);
|
||
|
||
#ifdef HAVE_cc0
|
||
/* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
|
||
if cc0 isn't set. */
|
||
note = find_reg_note (insn, REG_CC_SETTER, NULL_RTX);
|
||
if (note)
|
||
insn = XEXP (note, 0);
|
||
else
|
||
{
|
||
rtx maybe_cc0_setter = prev_nonnote_insn (insn);
|
||
if (maybe_cc0_setter
|
||
&& INSN_P (maybe_cc0_setter)
|
||
&& sets_cc0_p (PATTERN (maybe_cc0_setter)))
|
||
insn = maybe_cc0_setter;
|
||
}
|
||
#endif
|
||
/* FIXME: What if something in cc0/jump uses value set in new insn? */
|
||
new_insn = emit_insn_before_noloc (pat, insn);
|
||
}
|
||
|
||
/* Likewise if the last insn is a call, as will happen in the presence
|
||
of exception handling. */
|
||
else if (GET_CODE (insn) == CALL_INSN
|
||
&& (bb->succ->succ_next || (bb->succ->flags & EDGE_ABNORMAL)))
|
||
{
|
||
/* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
|
||
we search backward and place the instructions before the first
|
||
parameter is loaded. Do this for everyone for consistency and a
|
||
presumption that we'll get better code elsewhere as well.
|
||
|
||
It should always be the case that we can put these instructions
|
||
anywhere in the basic block with performing PRE optimizations.
|
||
Check this. */
|
||
|
||
if (pre
|
||
&& !TEST_BIT (antloc[bb->index], expr->bitmap_index)
|
||
&& !TEST_BIT (transp[bb->index], expr->bitmap_index))
|
||
abort ();
|
||
|
||
/* Since different machines initialize their parameter registers
|
||
in different orders, assume nothing. Collect the set of all
|
||
parameter registers. */
|
||
insn = find_first_parameter_load (insn, BB_HEAD (bb));
|
||
|
||
/* If we found all the parameter loads, then we want to insert
|
||
before the first parameter load.
|
||
|
||
If we did not find all the parameter loads, then we might have
|
||
stopped on the head of the block, which could be a CODE_LABEL.
|
||
If we inserted before the CODE_LABEL, then we would be putting
|
||
the insn in the wrong basic block. In that case, put the insn
|
||
after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
|
||
while (GET_CODE (insn) == CODE_LABEL
|
||
|| NOTE_INSN_BASIC_BLOCK_P (insn))
|
||
insn = NEXT_INSN (insn);
|
||
|
||
new_insn = emit_insn_before_noloc (pat, insn);
|
||
}
|
||
else
|
||
new_insn = emit_insn_after_noloc (pat, insn);
|
||
|
||
while (1)
|
||
{
|
||
if (INSN_P (pat))
|
||
{
|
||
add_label_notes (PATTERN (pat), new_insn);
|
||
note_stores (PATTERN (pat), record_set_info, pat);
|
||
}
|
||
if (pat == pat_end)
|
||
break;
|
||
pat = NEXT_INSN (pat);
|
||
}
|
||
|
||
gcse_create_count++;
|
||
|
||
if (gcse_file)
|
||
{
|
||
fprintf (gcse_file, "PRE/HOIST: end of bb %d, insn %d, ",
|
||
bb->index, INSN_UID (new_insn));
|
||
fprintf (gcse_file, "copying expression %d to reg %d\n",
|
||
expr->bitmap_index, regno);
|
||
}
|
||
}
|
||
|
||
/* Insert partially redundant expressions on edges in the CFG to make
|
||
the expressions fully redundant. */
|
||
|
||
static int
|
||
pre_edge_insert (struct edge_list *edge_list, struct expr **index_map)
|
||
{
|
||
int e, i, j, num_edges, set_size, did_insert = 0;
|
||
sbitmap *inserted;
|
||
|
||
/* Where PRE_INSERT_MAP is nonzero, we add the expression on that edge
|
||
if it reaches any of the deleted expressions. */
|
||
|
||
set_size = pre_insert_map[0]->size;
|
||
num_edges = NUM_EDGES (edge_list);
|
||
inserted = sbitmap_vector_alloc (num_edges, expr_hash_table.n_elems);
|
||
sbitmap_vector_zero (inserted, num_edges);
|
||
|
||
for (e = 0; e < num_edges; e++)
|
||
{
|
||
int indx;
|
||
basic_block bb = INDEX_EDGE_PRED_BB (edge_list, e);
|
||
|
||
for (i = indx = 0; i < set_size; i++, indx += SBITMAP_ELT_BITS)
|
||
{
|
||
SBITMAP_ELT_TYPE insert = pre_insert_map[e]->elms[i];
|
||
|
||
for (j = indx; insert && j < (int) expr_hash_table.n_elems; j++, insert >>= 1)
|
||
if ((insert & 1) != 0 && index_map[j]->reaching_reg != NULL_RTX)
|
||
{
|
||
struct expr *expr = index_map[j];
|
||
struct occr *occr;
|
||
|
||
/* Now look at each deleted occurrence of this expression. */
|
||
for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
|
||
{
|
||
if (! occr->deleted_p)
|
||
continue;
|
||
|
||
/* Insert this expression on this edge if if it would
|
||
reach the deleted occurrence in BB. */
|
||
if (!TEST_BIT (inserted[e], j))
|
||
{
|
||
rtx insn;
|
||
edge eg = INDEX_EDGE (edge_list, e);
|
||
|
||
/* We can't insert anything on an abnormal and
|
||
critical edge, so we insert the insn at the end of
|
||
the previous block. There are several alternatives
|
||
detailed in Morgans book P277 (sec 10.5) for
|
||
handling this situation. This one is easiest for
|
||
now. */
|
||
|
||
if ((eg->flags & EDGE_ABNORMAL) == EDGE_ABNORMAL)
|
||
insert_insn_end_bb (index_map[j], bb, 0);
|
||
else
|
||
{
|
||
insn = process_insert_insn (index_map[j]);
|
||
insert_insn_on_edge (insn, eg);
|
||
}
|
||
|
||
if (gcse_file)
|
||
{
|
||
fprintf (gcse_file, "PRE/HOIST: edge (%d,%d), ",
|
||
bb->index,
|
||
INDEX_EDGE_SUCC_BB (edge_list, e)->index);
|
||
fprintf (gcse_file, "copy expression %d\n",
|
||
expr->bitmap_index);
|
||
}
|
||
|
||
update_ld_motion_stores (expr);
|
||
SET_BIT (inserted[e], j);
|
||
did_insert = 1;
|
||
gcse_create_count++;
|
||
}
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
sbitmap_vector_free (inserted);
|
||
return did_insert;
|
||
}
|
||
|
||
/* Copy the result of EXPR->EXPR generated by INSN to EXPR->REACHING_REG.
|
||
Given "old_reg <- expr" (INSN), instead of adding after it
|
||
reaching_reg <- old_reg
|
||
it's better to do the following:
|
||
reaching_reg <- expr
|
||
old_reg <- reaching_reg
|
||
because this way copy propagation can discover additional PRE
|
||
opportunities. But if this fails, we try the old way.
|
||
When "expr" is a store, i.e.
|
||
given "MEM <- old_reg", instead of adding after it
|
||
reaching_reg <- old_reg
|
||
it's better to add it before as follows:
|
||
reaching_reg <- old_reg
|
||
MEM <- reaching_reg. */
|
||
|
||
static void
|
||
pre_insert_copy_insn (struct expr *expr, rtx insn)
|
||
{
|
||
rtx reg = expr->reaching_reg;
|
||
int regno = REGNO (reg);
|
||
int indx = expr->bitmap_index;
|
||
rtx pat = PATTERN (insn);
|
||
rtx set, new_insn;
|
||
rtx old_reg;
|
||
int i;
|
||
|
||
/* This block matches the logic in hash_scan_insn. */
|
||
if (GET_CODE (pat) == SET)
|
||
set = pat;
|
||
else if (GET_CODE (pat) == PARALLEL)
|
||
{
|
||
/* Search through the parallel looking for the set whose
|
||
source was the expression that we're interested in. */
|
||
set = NULL_RTX;
|
||
for (i = 0; i < XVECLEN (pat, 0); i++)
|
||
{
|
||
rtx x = XVECEXP (pat, 0, i);
|
||
if (GET_CODE (x) == SET
|
||
&& expr_equiv_p (SET_SRC (x), expr->expr))
|
||
{
|
||
set = x;
|
||
break;
|
||
}
|
||
}
|
||
}
|
||
else
|
||
abort ();
|
||
|
||
if (GET_CODE (SET_DEST (set)) == REG)
|
||
{
|
||
old_reg = SET_DEST (set);
|
||
/* Check if we can modify the set destination in the original insn. */
|
||
if (validate_change (insn, &SET_DEST (set), reg, 0))
|
||
{
|
||
new_insn = gen_move_insn (old_reg, reg);
|
||
new_insn = emit_insn_after (new_insn, insn);
|
||
|
||
/* Keep register set table up to date. */
|
||
replace_one_set (REGNO (old_reg), insn, new_insn);
|
||
record_one_set (regno, insn);
|
||
}
|
||
else
|
||
{
|
||
new_insn = gen_move_insn (reg, old_reg);
|
||
new_insn = emit_insn_after (new_insn, insn);
|
||
|
||
/* Keep register set table up to date. */
|
||
record_one_set (regno, new_insn);
|
||
}
|
||
}
|
||
else /* This is possible only in case of a store to memory. */
|
||
{
|
||
old_reg = SET_SRC (set);
|
||
new_insn = gen_move_insn (reg, old_reg);
|
||
|
||
/* Check if we can modify the set source in the original insn. */
|
||
if (validate_change (insn, &SET_SRC (set), reg, 0))
|
||
new_insn = emit_insn_before (new_insn, insn);
|
||
else
|
||
new_insn = emit_insn_after (new_insn, insn);
|
||
|
||
/* Keep register set table up to date. */
|
||
record_one_set (regno, new_insn);
|
||
}
|
||
|
||
gcse_create_count++;
|
||
|
||
if (gcse_file)
|
||
fprintf (gcse_file,
|
||
"PRE: bb %d, insn %d, copy expression %d in insn %d to reg %d\n",
|
||
BLOCK_NUM (insn), INSN_UID (new_insn), indx,
|
||
INSN_UID (insn), regno);
|
||
}
|
||
|
||
/* Copy available expressions that reach the redundant expression
|
||
to `reaching_reg'. */
|
||
|
||
static void
|
||
pre_insert_copies (void)
|
||
{
|
||
unsigned int i, added_copy;
|
||
struct expr *expr;
|
||
struct occr *occr;
|
||
struct occr *avail;
|
||
|
||
/* For each available expression in the table, copy the result to
|
||
`reaching_reg' if the expression reaches a deleted one.
|
||
|
||
??? The current algorithm is rather brute force.
|
||
Need to do some profiling. */
|
||
|
||
for (i = 0; i < expr_hash_table.size; i++)
|
||
for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
|
||
{
|
||
/* If the basic block isn't reachable, PPOUT will be TRUE. However,
|
||
we don't want to insert a copy here because the expression may not
|
||
really be redundant. So only insert an insn if the expression was
|
||
deleted. This test also avoids further processing if the
|
||
expression wasn't deleted anywhere. */
|
||
if (expr->reaching_reg == NULL)
|
||
continue;
|
||
|
||
/* Set when we add a copy for that expression. */
|
||
added_copy = 0;
|
||
|
||
for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
|
||
{
|
||
if (! occr->deleted_p)
|
||
continue;
|
||
|
||
for (avail = expr->avail_occr; avail != NULL; avail = avail->next)
|
||
{
|
||
rtx insn = avail->insn;
|
||
|
||
/* No need to handle this one if handled already. */
|
||
if (avail->copied_p)
|
||
continue;
|
||
|
||
/* Don't handle this one if it's a redundant one. */
|
||
if (TEST_BIT (pre_redundant_insns, INSN_CUID (insn)))
|
||
continue;
|
||
|
||
/* Or if the expression doesn't reach the deleted one. */
|
||
if (! pre_expr_reaches_here_p (BLOCK_FOR_INSN (avail->insn),
|
||
expr,
|
||
BLOCK_FOR_INSN (occr->insn)))
|
||
continue;
|
||
|
||
added_copy = 1;
|
||
|
||
/* Copy the result of avail to reaching_reg. */
|
||
pre_insert_copy_insn (expr, insn);
|
||
avail->copied_p = 1;
|
||
}
|
||
}
|
||
|
||
if (added_copy)
|
||
update_ld_motion_stores (expr);
|
||
}
|
||
}
|
||
|
||
/* Emit move from SRC to DEST noting the equivalence with expression computed
|
||
in INSN. */
|
||
static rtx
|
||
gcse_emit_move_after (rtx src, rtx dest, rtx insn)
|
||
{
|
||
rtx new;
|
||
rtx set = single_set (insn), set2;
|
||
rtx note;
|
||
rtx eqv;
|
||
|
||
/* This should never fail since we're creating a reg->reg copy
|
||
we've verified to be valid. */
|
||
|
||
new = emit_insn_after (gen_move_insn (dest, src), insn);
|
||
|
||
/* Note the equivalence for local CSE pass. */
|
||
set2 = single_set (new);
|
||
if (!set2 || !rtx_equal_p (SET_DEST (set2), dest))
|
||
return new;
|
||
if ((note = find_reg_equal_equiv_note (insn)))
|
||
eqv = XEXP (note, 0);
|
||
else
|
||
eqv = SET_SRC (set);
|
||
|
||
set_unique_reg_note (new, REG_EQUAL, copy_insn_1 (eqv));
|
||
|
||
return new;
|
||
}
|
||
|
||
/* Delete redundant computations.
|
||
Deletion is done by changing the insn to copy the `reaching_reg' of
|
||
the expression into the result of the SET. It is left to later passes
|
||
(cprop, cse2, flow, combine, regmove) to propagate the copy or eliminate it.
|
||
|
||
Returns nonzero if a change is made. */
|
||
|
||
static int
|
||
pre_delete (void)
|
||
{
|
||
unsigned int i;
|
||
int changed;
|
||
struct expr *expr;
|
||
struct occr *occr;
|
||
|
||
changed = 0;
|
||
for (i = 0; i < expr_hash_table.size; i++)
|
||
for (expr = expr_hash_table.table[i];
|
||
expr != NULL;
|
||
expr = expr->next_same_hash)
|
||
{
|
||
int indx = expr->bitmap_index;
|
||
|
||
/* We only need to search antic_occr since we require
|
||
ANTLOC != 0. */
|
||
|
||
for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
|
||
{
|
||
rtx insn = occr->insn;
|
||
rtx set;
|
||
basic_block bb = BLOCK_FOR_INSN (insn);
|
||
|
||
/* We only delete insns that have a single_set. */
|
||
if (TEST_BIT (pre_delete_map[bb->index], indx)
|
||
&& (set = single_set (insn)) != 0)
|
||
{
|
||
/* Create a pseudo-reg to store the result of reaching
|
||
expressions into. Get the mode for the new pseudo from
|
||
the mode of the original destination pseudo. */
|
||
if (expr->reaching_reg == NULL)
|
||
expr->reaching_reg
|
||
= gen_reg_rtx (GET_MODE (SET_DEST (set)));
|
||
|
||
gcse_emit_move_after (expr->reaching_reg, SET_DEST (set), insn);
|
||
delete_insn (insn);
|
||
occr->deleted_p = 1;
|
||
SET_BIT (pre_redundant_insns, INSN_CUID (insn));
|
||
changed = 1;
|
||
gcse_subst_count++;
|
||
|
||
if (gcse_file)
|
||
{
|
||
fprintf (gcse_file,
|
||
"PRE: redundant insn %d (expression %d) in ",
|
||
INSN_UID (insn), indx);
|
||
fprintf (gcse_file, "bb %d, reaching reg is %d\n",
|
||
bb->index, REGNO (expr->reaching_reg));
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
return changed;
|
||
}
|
||
|
||
/* Perform GCSE optimizations using PRE.
|
||
This is called by one_pre_gcse_pass after all the dataflow analysis
|
||
has been done.
|
||
|
||
This is based on the original Morel-Renvoise paper Fred Chow's thesis, and
|
||
lazy code motion from Knoop, Ruthing and Steffen as described in Advanced
|
||
Compiler Design and Implementation.
|
||
|
||
??? A new pseudo reg is created to hold the reaching expression. The nice
|
||
thing about the classical approach is that it would try to use an existing
|
||
reg. If the register can't be adequately optimized [i.e. we introduce
|
||
reload problems], one could add a pass here to propagate the new register
|
||
through the block.
|
||
|
||
??? We don't handle single sets in PARALLELs because we're [currently] not
|
||
able to copy the rest of the parallel when we insert copies to create full
|
||
redundancies from partial redundancies. However, there's no reason why we
|
||
can't handle PARALLELs in the cases where there are no partial
|
||
redundancies. */
|
||
|
||
static int
|
||
pre_gcse (void)
|
||
{
|
||
unsigned int i;
|
||
int did_insert, changed;
|
||
struct expr **index_map;
|
||
struct expr *expr;
|
||
|
||
/* Compute a mapping from expression number (`bitmap_index') to
|
||
hash table entry. */
|
||
|
||
index_map = xcalloc (expr_hash_table.n_elems, sizeof (struct expr *));
|
||
for (i = 0; i < expr_hash_table.size; i++)
|
||
for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
|
||
index_map[expr->bitmap_index] = expr;
|
||
|
||
/* Reset bitmap used to track which insns are redundant. */
|
||
pre_redundant_insns = sbitmap_alloc (max_cuid);
|
||
sbitmap_zero (pre_redundant_insns);
|
||
|
||
/* Delete the redundant insns first so that
|
||
- we know what register to use for the new insns and for the other
|
||
ones with reaching expressions
|
||
- we know which insns are redundant when we go to create copies */
|
||
|
||
changed = pre_delete ();
|
||
|
||
did_insert = pre_edge_insert (edge_list, index_map);
|
||
|
||
/* In other places with reaching expressions, copy the expression to the
|
||
specially allocated pseudo-reg that reaches the redundant expr. */
|
||
pre_insert_copies ();
|
||
if (did_insert)
|
||
{
|
||
commit_edge_insertions ();
|
||
changed = 1;
|
||
}
|
||
|
||
free (index_map);
|
||
sbitmap_free (pre_redundant_insns);
|
||
return changed;
|
||
}
|
||
|
||
/* Top level routine to perform one PRE GCSE pass.
|
||
|
||
Return nonzero if a change was made. */
|
||
|
||
static int
|
||
one_pre_gcse_pass (int pass)
|
||
{
|
||
int changed = 0;
|
||
|
||
gcse_subst_count = 0;
|
||
gcse_create_count = 0;
|
||
|
||
alloc_hash_table (max_cuid, &expr_hash_table, 0);
|
||
add_noreturn_fake_exit_edges ();
|
||
if (flag_gcse_lm)
|
||
compute_ld_motion_mems ();
|
||
|
||
compute_hash_table (&expr_hash_table);
|
||
trim_ld_motion_mems ();
|
||
if (gcse_file)
|
||
dump_hash_table (gcse_file, "Expression", &expr_hash_table);
|
||
|
||
if (expr_hash_table.n_elems > 0)
|
||
{
|
||
alloc_pre_mem (last_basic_block, expr_hash_table.n_elems);
|
||
compute_pre_data ();
|
||
changed |= pre_gcse ();
|
||
free_edge_list (edge_list);
|
||
free_pre_mem ();
|
||
}
|
||
|
||
free_ldst_mems ();
|
||
remove_fake_edges ();
|
||
free_hash_table (&expr_hash_table);
|
||
|
||
if (gcse_file)
|
||
{
|
||
fprintf (gcse_file, "\nPRE GCSE of %s, pass %d: %d bytes needed, ",
|
||
current_function_name (), pass, bytes_used);
|
||
fprintf (gcse_file, "%d substs, %d insns created\n",
|
||
gcse_subst_count, gcse_create_count);
|
||
}
|
||
|
||
return changed;
|
||
}
|
||
|
||
/* If X contains any LABEL_REF's, add REG_LABEL notes for them to INSN.
|
||
If notes are added to an insn which references a CODE_LABEL, the
|
||
LABEL_NUSES count is incremented. We have to add REG_LABEL notes,
|
||
because the following loop optimization pass requires them. */
|
||
|
||
/* ??? This is very similar to the loop.c add_label_notes function. We
|
||
could probably share code here. */
|
||
|
||
/* ??? If there was a jump optimization pass after gcse and before loop,
|
||
then we would not need to do this here, because jump would add the
|
||
necessary REG_LABEL notes. */
|
||
|
||
static void
|
||
add_label_notes (rtx x, rtx insn)
|
||
{
|
||
enum rtx_code code = GET_CODE (x);
|
||
int i, j;
|
||
const char *fmt;
|
||
|
||
if (code == LABEL_REF && !LABEL_REF_NONLOCAL_P (x))
|
||
{
|
||
/* This code used to ignore labels that referred to dispatch tables to
|
||
avoid flow generating (slightly) worse code.
|
||
|
||
We no longer ignore such label references (see LABEL_REF handling in
|
||
mark_jump_label for additional information). */
|
||
|
||
REG_NOTES (insn) = gen_rtx_INSN_LIST (REG_LABEL, XEXP (x, 0),
|
||
REG_NOTES (insn));
|
||
if (LABEL_P (XEXP (x, 0)))
|
||
LABEL_NUSES (XEXP (x, 0))++;
|
||
return;
|
||
}
|
||
|
||
for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
|
||
{
|
||
if (fmt[i] == 'e')
|
||
add_label_notes (XEXP (x, i), insn);
|
||
else if (fmt[i] == 'E')
|
||
for (j = XVECLEN (x, i) - 1; j >= 0; j--)
|
||
add_label_notes (XVECEXP (x, i, j), insn);
|
||
}
|
||
}
|
||
|
||
/* Compute transparent outgoing information for each block.
|
||
|
||
An expression is transparent to an edge unless it is killed by
|
||
the edge itself. This can only happen with abnormal control flow,
|
||
when the edge is traversed through a call. This happens with
|
||
non-local labels and exceptions.
|
||
|
||
This would not be necessary if we split the edge. While this is
|
||
normally impossible for abnormal critical edges, with some effort
|
||
it should be possible with exception handling, since we still have
|
||
control over which handler should be invoked. But due to increased
|
||
EH table sizes, this may not be worthwhile. */
|
||
|
||
static void
|
||
compute_transpout (void)
|
||
{
|
||
basic_block bb;
|
||
unsigned int i;
|
||
struct expr *expr;
|
||
|
||
sbitmap_vector_ones (transpout, last_basic_block);
|
||
|
||
FOR_EACH_BB (bb)
|
||
{
|
||
/* Note that flow inserted a nop a the end of basic blocks that
|
||
end in call instructions for reasons other than abnormal
|
||
control flow. */
|
||
if (GET_CODE (BB_END (bb)) != CALL_INSN)
|
||
continue;
|
||
|
||
for (i = 0; i < expr_hash_table.size; i++)
|
||
for (expr = expr_hash_table.table[i]; expr ; expr = expr->next_same_hash)
|
||
if (GET_CODE (expr->expr) == MEM)
|
||
{
|
||
if (GET_CODE (XEXP (expr->expr, 0)) == SYMBOL_REF
|
||
&& CONSTANT_POOL_ADDRESS_P (XEXP (expr->expr, 0)))
|
||
continue;
|
||
|
||
/* ??? Optimally, we would use interprocedural alias
|
||
analysis to determine if this mem is actually killed
|
||
by this call. */
|
||
RESET_BIT (transpout[bb->index], expr->bitmap_index);
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Removal of useless null pointer checks */
|
||
|
||
/* Called via note_stores. X is set by SETTER. If X is a register we must
|
||
invalidate nonnull_local and set nonnull_killed. DATA is really a
|
||
`null_pointer_info *'.
|
||
|
||
We ignore hard registers. */
|
||
|
||
static void
|
||
invalidate_nonnull_info (rtx x, rtx setter ATTRIBUTE_UNUSED, void *data)
|
||
{
|
||
unsigned int regno;
|
||
struct null_pointer_info *npi = (struct null_pointer_info *) data;
|
||
|
||
while (GET_CODE (x) == SUBREG)
|
||
x = SUBREG_REG (x);
|
||
|
||
/* Ignore anything that is not a register or is a hard register. */
|
||
if (GET_CODE (x) != REG
|
||
|| REGNO (x) < npi->min_reg
|
||
|| REGNO (x) >= npi->max_reg)
|
||
return;
|
||
|
||
regno = REGNO (x) - npi->min_reg;
|
||
|
||
RESET_BIT (npi->nonnull_local[npi->current_block->index], regno);
|
||
SET_BIT (npi->nonnull_killed[npi->current_block->index], regno);
|
||
}
|
||
|
||
/* Do null-pointer check elimination for the registers indicated in
|
||
NPI. NONNULL_AVIN and NONNULL_AVOUT are pre-allocated sbitmaps;
|
||
they are not our responsibility to free. */
|
||
|
||
static int
|
||
delete_null_pointer_checks_1 (unsigned int *block_reg, sbitmap *nonnull_avin,
|
||
sbitmap *nonnull_avout,
|
||
struct null_pointer_info *npi)
|
||
{
|
||
basic_block bb, current_block;
|
||
sbitmap *nonnull_local = npi->nonnull_local;
|
||
sbitmap *nonnull_killed = npi->nonnull_killed;
|
||
int something_changed = 0;
|
||
|
||
/* Compute local properties, nonnull and killed. A register will have
|
||
the nonnull property if at the end of the current block its value is
|
||
known to be nonnull. The killed property indicates that somewhere in
|
||
the block any information we had about the register is killed.
|
||
|
||
Note that a register can have both properties in a single block. That
|
||
indicates that it's killed, then later in the block a new value is
|
||
computed. */
|
||
sbitmap_vector_zero (nonnull_local, last_basic_block);
|
||
sbitmap_vector_zero (nonnull_killed, last_basic_block);
|
||
|
||
FOR_EACH_BB (current_block)
|
||
{
|
||
rtx insn, stop_insn;
|
||
|
||
/* Set the current block for invalidate_nonnull_info. */
|
||
npi->current_block = current_block;
|
||
|
||
/* Scan each insn in the basic block looking for memory references and
|
||
register sets. */
|
||
stop_insn = NEXT_INSN (BB_END (current_block));
|
||
for (insn = BB_HEAD (current_block);
|
||
insn != stop_insn;
|
||
insn = NEXT_INSN (insn))
|
||
{
|
||
rtx set;
|
||
rtx reg;
|
||
|
||
/* Ignore anything that is not a normal insn. */
|
||
if (! INSN_P (insn))
|
||
continue;
|
||
|
||
/* Basically ignore anything that is not a simple SET. We do have
|
||
to make sure to invalidate nonnull_local and set nonnull_killed
|
||
for such insns though. */
|
||
set = single_set (insn);
|
||
if (!set)
|
||
{
|
||
note_stores (PATTERN (insn), invalidate_nonnull_info, npi);
|
||
continue;
|
||
}
|
||
|
||
/* See if we've got a usable memory load. We handle it first
|
||
in case it uses its address register as a dest (which kills
|
||
the nonnull property). */
|
||
if (GET_CODE (SET_SRC (set)) == MEM
|
||
&& GET_CODE ((reg = XEXP (SET_SRC (set), 0))) == REG
|
||
&& REGNO (reg) >= npi->min_reg
|
||
&& REGNO (reg) < npi->max_reg)
|
||
SET_BIT (nonnull_local[current_block->index],
|
||
REGNO (reg) - npi->min_reg);
|
||
|
||
/* Now invalidate stuff clobbered by this insn. */
|
||
note_stores (PATTERN (insn), invalidate_nonnull_info, npi);
|
||
|
||
/* And handle stores, we do these last since any sets in INSN can
|
||
not kill the nonnull property if it is derived from a MEM
|
||
appearing in a SET_DEST. */
|
||
if (GET_CODE (SET_DEST (set)) == MEM
|
||
&& GET_CODE ((reg = XEXP (SET_DEST (set), 0))) == REG
|
||
&& REGNO (reg) >= npi->min_reg
|
||
&& REGNO (reg) < npi->max_reg)
|
||
SET_BIT (nonnull_local[current_block->index],
|
||
REGNO (reg) - npi->min_reg);
|
||
}
|
||
}
|
||
|
||
/* Now compute global properties based on the local properties. This
|
||
is a classic global availability algorithm. */
|
||
compute_available (nonnull_local, nonnull_killed,
|
||
nonnull_avout, nonnull_avin);
|
||
|
||
/* Now look at each bb and see if it ends with a compare of a value
|
||
against zero. */
|
||
FOR_EACH_BB (bb)
|
||
{
|
||
rtx last_insn = BB_END (bb);
|
||
rtx condition, earliest;
|
||
int compare_and_branch;
|
||
|
||
/* Since MIN_REG is always at least FIRST_PSEUDO_REGISTER, and
|
||
since BLOCK_REG[BB] is zero if this block did not end with a
|
||
comparison against zero, this condition works. */
|
||
if (block_reg[bb->index] < npi->min_reg
|
||
|| block_reg[bb->index] >= npi->max_reg)
|
||
continue;
|
||
|
||
/* LAST_INSN is a conditional jump. Get its condition. */
|
||
condition = get_condition (last_insn, &earliest, false);
|
||
|
||
/* If we can't determine the condition then skip. */
|
||
if (! condition)
|
||
continue;
|
||
|
||
/* Is the register known to have a nonzero value? */
|
||
if (!TEST_BIT (nonnull_avout[bb->index], block_reg[bb->index] - npi->min_reg))
|
||
continue;
|
||
|
||
/* Try to compute whether the compare/branch at the loop end is one or
|
||
two instructions. */
|
||
if (earliest == last_insn)
|
||
compare_and_branch = 1;
|
||
else if (earliest == prev_nonnote_insn (last_insn))
|
||
compare_and_branch = 2;
|
||
else
|
||
continue;
|
||
|
||
/* We know the register in this comparison is nonnull at exit from
|
||
this block. We can optimize this comparison. */
|
||
if (GET_CODE (condition) == NE)
|
||
{
|
||
rtx new_jump;
|
||
|
||
new_jump = emit_jump_insn_after (gen_jump (JUMP_LABEL (last_insn)),
|
||
last_insn);
|
||
JUMP_LABEL (new_jump) = JUMP_LABEL (last_insn);
|
||
LABEL_NUSES (JUMP_LABEL (new_jump))++;
|
||
emit_barrier_after (new_jump);
|
||
}
|
||
|
||
something_changed = 1;
|
||
delete_insn (last_insn);
|
||
#ifdef HAVE_cc0
|
||
if (compare_and_branch == 2)
|
||
delete_insn (earliest);
|
||
#endif
|
||
purge_dead_edges (bb);
|
||
|
||
/* Don't check this block again. (Note that BB_END is
|
||
invalid here; we deleted the last instruction in the
|
||
block.) */
|
||
block_reg[bb->index] = 0;
|
||
}
|
||
|
||
return something_changed;
|
||
}
|
||
|
||
/* Find EQ/NE comparisons against zero which can be (indirectly) evaluated
|
||
at compile time.
|
||
|
||
This is conceptually similar to global constant/copy propagation and
|
||
classic global CSE (it even uses the same dataflow equations as cprop).
|
||
|
||
If a register is used as memory address with the form (mem (reg)), then we
|
||
know that REG can not be zero at that point in the program. Any instruction
|
||
which sets REG "kills" this property.
|
||
|
||
So, if every path leading to a conditional branch has an available memory
|
||
reference of that form, then we know the register can not have the value
|
||
zero at the conditional branch.
|
||
|
||
So we merely need to compute the local properties and propagate that data
|
||
around the cfg, then optimize where possible.
|
||
|
||
We run this pass two times. Once before CSE, then again after CSE. This
|
||
has proven to be the most profitable approach. It is rare for new
|
||
optimization opportunities of this nature to appear after the first CSE
|
||
pass.
|
||
|
||
This could probably be integrated with global cprop with a little work. */
|
||
|
||
int
|
||
delete_null_pointer_checks (rtx f ATTRIBUTE_UNUSED)
|
||
{
|
||
sbitmap *nonnull_avin, *nonnull_avout;
|
||
unsigned int *block_reg;
|
||
basic_block bb;
|
||
int reg;
|
||
int regs_per_pass;
|
||
int max_reg = max_reg_num ();
|
||
struct null_pointer_info npi;
|
||
int something_changed = 0;
|
||
|
||
/* If we have only a single block, or it is too expensive, give up. */
|
||
if (n_basic_blocks <= 1
|
||
|| is_too_expensive (_ ("NULL pointer checks disabled")))
|
||
return 0;
|
||
|
||
/* We need four bitmaps, each with a bit for each register in each
|
||
basic block. */
|
||
regs_per_pass = get_bitmap_width (4, last_basic_block, max_reg);
|
||
|
||
/* Allocate bitmaps to hold local and global properties. */
|
||
npi.nonnull_local = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
|
||
npi.nonnull_killed = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
|
||
nonnull_avin = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
|
||
nonnull_avout = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
|
||
|
||
/* Go through the basic blocks, seeing whether or not each block
|
||
ends with a conditional branch whose condition is a comparison
|
||
against zero. Record the register compared in BLOCK_REG. */
|
||
block_reg = xcalloc (last_basic_block, sizeof (int));
|
||
FOR_EACH_BB (bb)
|
||
{
|
||
rtx last_insn = BB_END (bb);
|
||
rtx condition, earliest, reg;
|
||
|
||
/* We only want conditional branches. */
|
||
if (GET_CODE (last_insn) != JUMP_INSN
|
||
|| !any_condjump_p (last_insn)
|
||
|| !onlyjump_p (last_insn))
|
||
continue;
|
||
|
||
/* LAST_INSN is a conditional jump. Get its condition. */
|
||
condition = get_condition (last_insn, &earliest, false);
|
||
|
||
/* If we were unable to get the condition, or it is not an equality
|
||
comparison against zero then there's nothing we can do. */
|
||
if (!condition
|
||
|| (GET_CODE (condition) != NE && GET_CODE (condition) != EQ)
|
||
|| GET_CODE (XEXP (condition, 1)) != CONST_INT
|
||
|| (XEXP (condition, 1)
|
||
!= CONST0_RTX (GET_MODE (XEXP (condition, 0)))))
|
||
continue;
|
||
|
||
/* We must be checking a register against zero. */
|
||
reg = XEXP (condition, 0);
|
||
if (GET_CODE (reg) != REG)
|
||
continue;
|
||
|
||
block_reg[bb->index] = REGNO (reg);
|
||
}
|
||
|
||
/* Go through the algorithm for each block of registers. */
|
||
for (reg = FIRST_PSEUDO_REGISTER; reg < max_reg; reg += regs_per_pass)
|
||
{
|
||
npi.min_reg = reg;
|
||
npi.max_reg = MIN (reg + regs_per_pass, max_reg);
|
||
something_changed |= delete_null_pointer_checks_1 (block_reg,
|
||
nonnull_avin,
|
||
nonnull_avout,
|
||
&npi);
|
||
}
|
||
|
||
/* Free the table of registers compared at the end of every block. */
|
||
free (block_reg);
|
||
|
||
/* Free bitmaps. */
|
||
sbitmap_vector_free (npi.nonnull_local);
|
||
sbitmap_vector_free (npi.nonnull_killed);
|
||
sbitmap_vector_free (nonnull_avin);
|
||
sbitmap_vector_free (nonnull_avout);
|
||
|
||
return something_changed;
|
||
}
|
||
|
||
/* Code Hoisting variables and subroutines. */
|
||
|
||
/* Very busy expressions. */
|
||
static sbitmap *hoist_vbein;
|
||
static sbitmap *hoist_vbeout;
|
||
|
||
/* Hoistable expressions. */
|
||
static sbitmap *hoist_exprs;
|
||
|
||
/* ??? We could compute post dominators and run this algorithm in
|
||
reverse to perform tail merging, doing so would probably be
|
||
more effective than the tail merging code in jump.c.
|
||
|
||
It's unclear if tail merging could be run in parallel with
|
||
code hoisting. It would be nice. */
|
||
|
||
/* Allocate vars used for code hoisting analysis. */
|
||
|
||
static void
|
||
alloc_code_hoist_mem (int n_blocks, int n_exprs)
|
||
{
|
||
antloc = sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
transp = sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
comp = sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
|
||
hoist_vbein = sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
hoist_vbeout = sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
hoist_exprs = sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
transpout = sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
}
|
||
|
||
/* Free vars used for code hoisting analysis. */
|
||
|
||
static void
|
||
free_code_hoist_mem (void)
|
||
{
|
||
sbitmap_vector_free (antloc);
|
||
sbitmap_vector_free (transp);
|
||
sbitmap_vector_free (comp);
|
||
|
||
sbitmap_vector_free (hoist_vbein);
|
||
sbitmap_vector_free (hoist_vbeout);
|
||
sbitmap_vector_free (hoist_exprs);
|
||
sbitmap_vector_free (transpout);
|
||
|
||
free_dominance_info (CDI_DOMINATORS);
|
||
}
|
||
|
||
/* Compute the very busy expressions at entry/exit from each block.
|
||
|
||
An expression is very busy if all paths from a given point
|
||
compute the expression. */
|
||
|
||
static void
|
||
compute_code_hoist_vbeinout (void)
|
||
{
|
||
int changed, passes;
|
||
basic_block bb;
|
||
|
||
sbitmap_vector_zero (hoist_vbeout, last_basic_block);
|
||
sbitmap_vector_zero (hoist_vbein, last_basic_block);
|
||
|
||
passes = 0;
|
||
changed = 1;
|
||
|
||
while (changed)
|
||
{
|
||
changed = 0;
|
||
|
||
/* We scan the blocks in the reverse order to speed up
|
||
the convergence. */
|
||
FOR_EACH_BB_REVERSE (bb)
|
||
{
|
||
changed |= sbitmap_a_or_b_and_c_cg (hoist_vbein[bb->index], antloc[bb->index],
|
||
hoist_vbeout[bb->index], transp[bb->index]);
|
||
if (bb->next_bb != EXIT_BLOCK_PTR)
|
||
sbitmap_intersection_of_succs (hoist_vbeout[bb->index], hoist_vbein, bb->index);
|
||
}
|
||
|
||
passes++;
|
||
}
|
||
|
||
if (gcse_file)
|
||
fprintf (gcse_file, "hoisting vbeinout computation: %d passes\n", passes);
|
||
}
|
||
|
||
/* Top level routine to do the dataflow analysis needed by code hoisting. */
|
||
|
||
static void
|
||
compute_code_hoist_data (void)
|
||
{
|
||
compute_local_properties (transp, comp, antloc, &expr_hash_table);
|
||
compute_transpout ();
|
||
compute_code_hoist_vbeinout ();
|
||
calculate_dominance_info (CDI_DOMINATORS);
|
||
if (gcse_file)
|
||
fprintf (gcse_file, "\n");
|
||
}
|
||
|
||
/* Determine if the expression identified by EXPR_INDEX would
|
||
reach BB unimpared if it was placed at the end of EXPR_BB.
|
||
|
||
It's unclear exactly what Muchnick meant by "unimpared". It seems
|
||
to me that the expression must either be computed or transparent in
|
||
*every* block in the path(s) from EXPR_BB to BB. Any other definition
|
||
would allow the expression to be hoisted out of loops, even if
|
||
the expression wasn't a loop invariant.
|
||
|
||
Contrast this to reachability for PRE where an expression is
|
||
considered reachable if *any* path reaches instead of *all*
|
||
paths. */
|
||
|
||
static int
|
||
hoist_expr_reaches_here_p (basic_block expr_bb, int expr_index, basic_block bb, char *visited)
|
||
{
|
||
edge pred;
|
||
int visited_allocated_locally = 0;
|
||
|
||
|
||
if (visited == NULL)
|
||
{
|
||
visited_allocated_locally = 1;
|
||
visited = xcalloc (last_basic_block, 1);
|
||
}
|
||
|
||
for (pred = bb->pred; pred != NULL; pred = pred->pred_next)
|
||
{
|
||
basic_block pred_bb = pred->src;
|
||
|
||
if (pred->src == ENTRY_BLOCK_PTR)
|
||
break;
|
||
else if (pred_bb == expr_bb)
|
||
continue;
|
||
else if (visited[pred_bb->index])
|
||
continue;
|
||
|
||
/* Does this predecessor generate this expression? */
|
||
else if (TEST_BIT (comp[pred_bb->index], expr_index))
|
||
break;
|
||
else if (! TEST_BIT (transp[pred_bb->index], expr_index))
|
||
break;
|
||
|
||
/* Not killed. */
|
||
else
|
||
{
|
||
visited[pred_bb->index] = 1;
|
||
if (! hoist_expr_reaches_here_p (expr_bb, expr_index,
|
||
pred_bb, visited))
|
||
break;
|
||
}
|
||
}
|
||
if (visited_allocated_locally)
|
||
free (visited);
|
||
|
||
return (pred == NULL);
|
||
}
|
||
|
||
/* Actually perform code hoisting. */
|
||
|
||
static void
|
||
hoist_code (void)
|
||
{
|
||
basic_block bb, dominated;
|
||
basic_block *domby;
|
||
unsigned int domby_len;
|
||
unsigned int i,j;
|
||
struct expr **index_map;
|
||
struct expr *expr;
|
||
|
||
sbitmap_vector_zero (hoist_exprs, last_basic_block);
|
||
|
||
/* Compute a mapping from expression number (`bitmap_index') to
|
||
hash table entry. */
|
||
|
||
index_map = xcalloc (expr_hash_table.n_elems, sizeof (struct expr *));
|
||
for (i = 0; i < expr_hash_table.size; i++)
|
||
for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
|
||
index_map[expr->bitmap_index] = expr;
|
||
|
||
/* Walk over each basic block looking for potentially hoistable
|
||
expressions, nothing gets hoisted from the entry block. */
|
||
FOR_EACH_BB (bb)
|
||
{
|
||
int found = 0;
|
||
int insn_inserted_p;
|
||
|
||
domby_len = get_dominated_by (CDI_DOMINATORS, bb, &domby);
|
||
/* Examine each expression that is very busy at the exit of this
|
||
block. These are the potentially hoistable expressions. */
|
||
for (i = 0; i < hoist_vbeout[bb->index]->n_bits; i++)
|
||
{
|
||
int hoistable = 0;
|
||
|
||
if (TEST_BIT (hoist_vbeout[bb->index], i)
|
||
&& TEST_BIT (transpout[bb->index], i))
|
||
{
|
||
/* We've found a potentially hoistable expression, now
|
||
we look at every block BB dominates to see if it
|
||
computes the expression. */
|
||
for (j = 0; j < domby_len; j++)
|
||
{
|
||
dominated = domby[j];
|
||
/* Ignore self dominance. */
|
||
if (bb == dominated)
|
||
continue;
|
||
/* We've found a dominated block, now see if it computes
|
||
the busy expression and whether or not moving that
|
||
expression to the "beginning" of that block is safe. */
|
||
if (!TEST_BIT (antloc[dominated->index], i))
|
||
continue;
|
||
|
||
/* Note if the expression would reach the dominated block
|
||
unimpared if it was placed at the end of BB.
|
||
|
||
Keep track of how many times this expression is hoistable
|
||
from a dominated block into BB. */
|
||
if (hoist_expr_reaches_here_p (bb, i, dominated, NULL))
|
||
hoistable++;
|
||
}
|
||
|
||
/* If we found more than one hoistable occurrence of this
|
||
expression, then note it in the bitmap of expressions to
|
||
hoist. It makes no sense to hoist things which are computed
|
||
in only one BB, and doing so tends to pessimize register
|
||
allocation. One could increase this value to try harder
|
||
to avoid any possible code expansion due to register
|
||
allocation issues; however experiments have shown that
|
||
the vast majority of hoistable expressions are only movable
|
||
from two successors, so raising this threshold is likely
|
||
to nullify any benefit we get from code hoisting. */
|
||
if (hoistable > 1)
|
||
{
|
||
SET_BIT (hoist_exprs[bb->index], i);
|
||
found = 1;
|
||
}
|
||
}
|
||
}
|
||
/* If we found nothing to hoist, then quit now. */
|
||
if (! found)
|
||
{
|
||
free (domby);
|
||
continue;
|
||
}
|
||
|
||
/* Loop over all the hoistable expressions. */
|
||
for (i = 0; i < hoist_exprs[bb->index]->n_bits; i++)
|
||
{
|
||
/* We want to insert the expression into BB only once, so
|
||
note when we've inserted it. */
|
||
insn_inserted_p = 0;
|
||
|
||
/* These tests should be the same as the tests above. */
|
||
if (TEST_BIT (hoist_exprs[bb->index], i))
|
||
{
|
||
/* We've found a potentially hoistable expression, now
|
||
we look at every block BB dominates to see if it
|
||
computes the expression. */
|
||
for (j = 0; j < domby_len; j++)
|
||
{
|
||
dominated = domby[j];
|
||
/* Ignore self dominance. */
|
||
if (bb == dominated)
|
||
continue;
|
||
|
||
/* We've found a dominated block, now see if it computes
|
||
the busy expression and whether or not moving that
|
||
expression to the "beginning" of that block is safe. */
|
||
if (!TEST_BIT (antloc[dominated->index], i))
|
||
continue;
|
||
|
||
/* The expression is computed in the dominated block and
|
||
it would be safe to compute it at the start of the
|
||
dominated block. Now we have to determine if the
|
||
expression would reach the dominated block if it was
|
||
placed at the end of BB. */
|
||
if (hoist_expr_reaches_here_p (bb, i, dominated, NULL))
|
||
{
|
||
struct expr *expr = index_map[i];
|
||
struct occr *occr = expr->antic_occr;
|
||
rtx insn;
|
||
rtx set;
|
||
|
||
/* Find the right occurrence of this expression. */
|
||
while (BLOCK_FOR_INSN (occr->insn) != dominated && occr)
|
||
occr = occr->next;
|
||
|
||
/* Should never happen. */
|
||
if (!occr)
|
||
abort ();
|
||
|
||
insn = occr->insn;
|
||
|
||
set = single_set (insn);
|
||
if (! set)
|
||
abort ();
|
||
|
||
/* Create a pseudo-reg to store the result of reaching
|
||
expressions into. Get the mode for the new pseudo
|
||
from the mode of the original destination pseudo. */
|
||
if (expr->reaching_reg == NULL)
|
||
expr->reaching_reg
|
||
= gen_reg_rtx (GET_MODE (SET_DEST (set)));
|
||
|
||
gcse_emit_move_after (expr->reaching_reg, SET_DEST (set), insn);
|
||
delete_insn (insn);
|
||
occr->deleted_p = 1;
|
||
if (!insn_inserted_p)
|
||
{
|
||
insert_insn_end_bb (index_map[i], bb, 0);
|
||
insn_inserted_p = 1;
|
||
}
|
||
}
|
||
}
|
||
}
|
||
}
|
||
free (domby);
|
||
}
|
||
|
||
free (index_map);
|
||
}
|
||
|
||
/* Top level routine to perform one code hoisting (aka unification) pass
|
||
|
||
Return nonzero if a change was made. */
|
||
|
||
static int
|
||
one_code_hoisting_pass (void)
|
||
{
|
||
int changed = 0;
|
||
|
||
alloc_hash_table (max_cuid, &expr_hash_table, 0);
|
||
compute_hash_table (&expr_hash_table);
|
||
if (gcse_file)
|
||
dump_hash_table (gcse_file, "Code Hosting Expressions", &expr_hash_table);
|
||
|
||
if (expr_hash_table.n_elems > 0)
|
||
{
|
||
alloc_code_hoist_mem (last_basic_block, expr_hash_table.n_elems);
|
||
compute_code_hoist_data ();
|
||
hoist_code ();
|
||
free_code_hoist_mem ();
|
||
}
|
||
|
||
free_hash_table (&expr_hash_table);
|
||
|
||
return changed;
|
||
}
|
||
|
||
/* Here we provide the things required to do store motion towards
|
||
the exit. In order for this to be effective, gcse also needed to
|
||
be taught how to move a load when it is kill only by a store to itself.
|
||
|
||
int i;
|
||
float a[10];
|
||
|
||
void foo(float scale)
|
||
{
|
||
for (i=0; i<10; i++)
|
||
a[i] *= scale;
|
||
}
|
||
|
||
'i' is both loaded and stored to in the loop. Normally, gcse cannot move
|
||
the load out since its live around the loop, and stored at the bottom
|
||
of the loop.
|
||
|
||
The 'Load Motion' referred to and implemented in this file is
|
||
an enhancement to gcse which when using edge based lcm, recognizes
|
||
this situation and allows gcse to move the load out of the loop.
|
||
|
||
Once gcse has hoisted the load, store motion can then push this
|
||
load towards the exit, and we end up with no loads or stores of 'i'
|
||
in the loop. */
|
||
|
||
/* This will search the ldst list for a matching expression. If it
|
||
doesn't find one, we create one and initialize it. */
|
||
|
||
static struct ls_expr *
|
||
ldst_entry (rtx x)
|
||
{
|
||
int do_not_record_p = 0;
|
||
struct ls_expr * ptr;
|
||
unsigned int hash;
|
||
|
||
hash = hash_expr_1 (x, GET_MODE (x), & do_not_record_p);
|
||
|
||
for (ptr = pre_ldst_mems; ptr != NULL; ptr = ptr->next)
|
||
if (ptr->hash_index == hash && expr_equiv_p (ptr->pattern, x))
|
||
return ptr;
|
||
|
||
ptr = xmalloc (sizeof (struct ls_expr));
|
||
|
||
ptr->next = pre_ldst_mems;
|
||
ptr->expr = NULL;
|
||
ptr->pattern = x;
|
||
ptr->pattern_regs = NULL_RTX;
|
||
ptr->loads = NULL_RTX;
|
||
ptr->stores = NULL_RTX;
|
||
ptr->reaching_reg = NULL_RTX;
|
||
ptr->invalid = 0;
|
||
ptr->index = 0;
|
||
ptr->hash_index = hash;
|
||
pre_ldst_mems = ptr;
|
||
|
||
return ptr;
|
||
}
|
||
|
||
/* Free up an individual ldst entry. */
|
||
|
||
static void
|
||
free_ldst_entry (struct ls_expr * ptr)
|
||
{
|
||
free_INSN_LIST_list (& ptr->loads);
|
||
free_INSN_LIST_list (& ptr->stores);
|
||
|
||
free (ptr);
|
||
}
|
||
|
||
/* Free up all memory associated with the ldst list. */
|
||
|
||
static void
|
||
free_ldst_mems (void)
|
||
{
|
||
while (pre_ldst_mems)
|
||
{
|
||
struct ls_expr * tmp = pre_ldst_mems;
|
||
|
||
pre_ldst_mems = pre_ldst_mems->next;
|
||
|
||
free_ldst_entry (tmp);
|
||
}
|
||
|
||
pre_ldst_mems = NULL;
|
||
}
|
||
|
||
/* Dump debugging info about the ldst list. */
|
||
|
||
static void
|
||
print_ldst_list (FILE * file)
|
||
{
|
||
struct ls_expr * ptr;
|
||
|
||
fprintf (file, "LDST list: \n");
|
||
|
||
for (ptr = first_ls_expr(); ptr != NULL; ptr = next_ls_expr (ptr))
|
||
{
|
||
fprintf (file, " Pattern (%3d): ", ptr->index);
|
||
|
||
print_rtl (file, ptr->pattern);
|
||
|
||
fprintf (file, "\n Loads : ");
|
||
|
||
if (ptr->loads)
|
||
print_rtl (file, ptr->loads);
|
||
else
|
||
fprintf (file, "(nil)");
|
||
|
||
fprintf (file, "\n Stores : ");
|
||
|
||
if (ptr->stores)
|
||
print_rtl (file, ptr->stores);
|
||
else
|
||
fprintf (file, "(nil)");
|
||
|
||
fprintf (file, "\n\n");
|
||
}
|
||
|
||
fprintf (file, "\n");
|
||
}
|
||
|
||
/* Returns 1 if X is in the list of ldst only expressions. */
|
||
|
||
static struct ls_expr *
|
||
find_rtx_in_ldst (rtx x)
|
||
{
|
||
struct ls_expr * ptr;
|
||
|
||
for (ptr = pre_ldst_mems; ptr != NULL; ptr = ptr->next)
|
||
if (expr_equiv_p (ptr->pattern, x) && ! ptr->invalid)
|
||
return ptr;
|
||
|
||
return NULL;
|
||
}
|
||
|
||
/* Assign each element of the list of mems a monotonically increasing value. */
|
||
|
||
static int
|
||
enumerate_ldsts (void)
|
||
{
|
||
struct ls_expr * ptr;
|
||
int n = 0;
|
||
|
||
for (ptr = pre_ldst_mems; ptr != NULL; ptr = ptr->next)
|
||
ptr->index = n++;
|
||
|
||
return n;
|
||
}
|
||
|
||
/* Return first item in the list. */
|
||
|
||
static inline struct ls_expr *
|
||
first_ls_expr (void)
|
||
{
|
||
return pre_ldst_mems;
|
||
}
|
||
|
||
/* Return the next item in the list after the specified one. */
|
||
|
||
static inline struct ls_expr *
|
||
next_ls_expr (struct ls_expr * ptr)
|
||
{
|
||
return ptr->next;
|
||
}
|
||
|
||
/* Load Motion for loads which only kill themselves. */
|
||
|
||
/* Return true if x is a simple MEM operation, with no registers or
|
||
side effects. These are the types of loads we consider for the
|
||
ld_motion list, otherwise we let the usual aliasing take care of it. */
|
||
|
||
static int
|
||
simple_mem (rtx x)
|
||
{
|
||
if (GET_CODE (x) != MEM)
|
||
return 0;
|
||
|
||
if (MEM_VOLATILE_P (x))
|
||
return 0;
|
||
|
||
if (GET_MODE (x) == BLKmode)
|
||
return 0;
|
||
|
||
/* If we are handling exceptions, we must be careful with memory references
|
||
that may trap. If we are not, the behavior is undefined, so we may just
|
||
continue. */
|
||
if (flag_non_call_exceptions && may_trap_p (x))
|
||
return 0;
|
||
|
||
if (side_effects_p (x))
|
||
return 0;
|
||
|
||
/* Do not consider function arguments passed on stack. */
|
||
if (reg_mentioned_p (stack_pointer_rtx, x))
|
||
return 0;
|
||
|
||
if (flag_float_store && FLOAT_MODE_P (GET_MODE (x)))
|
||
return 0;
|
||
|
||
return 1;
|
||
}
|
||
|
||
/* Make sure there isn't a buried reference in this pattern anywhere.
|
||
If there is, invalidate the entry for it since we're not capable
|
||
of fixing it up just yet.. We have to be sure we know about ALL
|
||
loads since the aliasing code will allow all entries in the
|
||
ld_motion list to not-alias itself. If we miss a load, we will get
|
||
the wrong value since gcse might common it and we won't know to
|
||
fix it up. */
|
||
|
||
static void
|
||
invalidate_any_buried_refs (rtx x)
|
||
{
|
||
const char * fmt;
|
||
int i, j;
|
||
struct ls_expr * ptr;
|
||
|
||
/* Invalidate it in the list. */
|
||
if (GET_CODE (x) == MEM && simple_mem (x))
|
||
{
|
||
ptr = ldst_entry (x);
|
||
ptr->invalid = 1;
|
||
}
|
||
|
||
/* Recursively process the insn. */
|
||
fmt = GET_RTX_FORMAT (GET_CODE (x));
|
||
|
||
for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0; i--)
|
||
{
|
||
if (fmt[i] == 'e')
|
||
invalidate_any_buried_refs (XEXP (x, i));
|
||
else if (fmt[i] == 'E')
|
||
for (j = XVECLEN (x, i) - 1; j >= 0; j--)
|
||
invalidate_any_buried_refs (XVECEXP (x, i, j));
|
||
}
|
||
}
|
||
|
||
/* Find all the 'simple' MEMs which are used in LOADs and STORES. Simple
|
||
being defined as MEM loads and stores to symbols, with no side effects
|
||
and no registers in the expression. For a MEM destination, we also
|
||
check that the insn is still valid if we replace the destination with a
|
||
REG, as is done in update_ld_motion_stores. If there are any uses/defs
|
||
which don't match this criteria, they are invalidated and trimmed out
|
||
later. */
|
||
|
||
static void
|
||
compute_ld_motion_mems (void)
|
||
{
|
||
struct ls_expr * ptr;
|
||
basic_block bb;
|
||
rtx insn;
|
||
|
||
pre_ldst_mems = NULL;
|
||
|
||
FOR_EACH_BB (bb)
|
||
{
|
||
for (insn = BB_HEAD (bb);
|
||
insn && insn != NEXT_INSN (BB_END (bb));
|
||
insn = NEXT_INSN (insn))
|
||
{
|
||
if (INSN_P (insn))
|
||
{
|
||
if (GET_CODE (PATTERN (insn)) == SET)
|
||
{
|
||
rtx src = SET_SRC (PATTERN (insn));
|
||
rtx dest = SET_DEST (PATTERN (insn));
|
||
|
||
/* Check for a simple LOAD... */
|
||
if (GET_CODE (src) == MEM && simple_mem (src))
|
||
{
|
||
ptr = ldst_entry (src);
|
||
if (GET_CODE (dest) == REG)
|
||
ptr->loads = alloc_INSN_LIST (insn, ptr->loads);
|
||
else
|
||
ptr->invalid = 1;
|
||
}
|
||
else
|
||
{
|
||
/* Make sure there isn't a buried load somewhere. */
|
||
invalidate_any_buried_refs (src);
|
||
}
|
||
|
||
/* Check for stores. Don't worry about aliased ones, they
|
||
will block any movement we might do later. We only care
|
||
about this exact pattern since those are the only
|
||
circumstance that we will ignore the aliasing info. */
|
||
if (GET_CODE (dest) == MEM && simple_mem (dest))
|
||
{
|
||
ptr = ldst_entry (dest);
|
||
|
||
if (GET_CODE (src) != MEM
|
||
&& GET_CODE (src) != ASM_OPERANDS
|
||
/* Check for REG manually since want_to_gcse_p
|
||
returns 0 for all REGs. */
|
||
&& (REG_P (src) || want_to_gcse_p (src)))
|
||
ptr->stores = alloc_INSN_LIST (insn, ptr->stores);
|
||
else
|
||
ptr->invalid = 1;
|
||
}
|
||
}
|
||
else
|
||
invalidate_any_buried_refs (PATTERN (insn));
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Remove any references that have been either invalidated or are not in the
|
||
expression list for pre gcse. */
|
||
|
||
static void
|
||
trim_ld_motion_mems (void)
|
||
{
|
||
struct ls_expr * * last = & pre_ldst_mems;
|
||
struct ls_expr * ptr = pre_ldst_mems;
|
||
|
||
while (ptr != NULL)
|
||
{
|
||
struct expr * expr;
|
||
|
||
/* Delete if entry has been made invalid. */
|
||
if (! ptr->invalid)
|
||
{
|
||
/* Delete if we cannot find this mem in the expression list. */
|
||
unsigned int hash = ptr->hash_index % expr_hash_table.size;
|
||
|
||
for (expr = expr_hash_table.table[hash];
|
||
expr != NULL;
|
||
expr = expr->next_same_hash)
|
||
if (expr_equiv_p (expr->expr, ptr->pattern))
|
||
break;
|
||
}
|
||
else
|
||
expr = (struct expr *) 0;
|
||
|
||
if (expr)
|
||
{
|
||
/* Set the expression field if we are keeping it. */
|
||
ptr->expr = expr;
|
||
last = & ptr->next;
|
||
ptr = ptr->next;
|
||
}
|
||
else
|
||
{
|
||
*last = ptr->next;
|
||
free_ldst_entry (ptr);
|
||
ptr = * last;
|
||
}
|
||
}
|
||
|
||
/* Show the world what we've found. */
|
||
if (gcse_file && pre_ldst_mems != NULL)
|
||
print_ldst_list (gcse_file);
|
||
}
|
||
|
||
/* This routine will take an expression which we are replacing with
|
||
a reaching register, and update any stores that are needed if
|
||
that expression is in the ld_motion list. Stores are updated by
|
||
copying their SRC to the reaching register, and then storing
|
||
the reaching register into the store location. These keeps the
|
||
correct value in the reaching register for the loads. */
|
||
|
||
static void
|
||
update_ld_motion_stores (struct expr * expr)
|
||
{
|
||
struct ls_expr * mem_ptr;
|
||
|
||
if ((mem_ptr = find_rtx_in_ldst (expr->expr)))
|
||
{
|
||
/* We can try to find just the REACHED stores, but is shouldn't
|
||
matter to set the reaching reg everywhere... some might be
|
||
dead and should be eliminated later. */
|
||
|
||
/* We replace (set mem expr) with (set reg expr) (set mem reg)
|
||
where reg is the reaching reg used in the load. We checked in
|
||
compute_ld_motion_mems that we can replace (set mem expr) with
|
||
(set reg expr) in that insn. */
|
||
rtx list = mem_ptr->stores;
|
||
|
||
for ( ; list != NULL_RTX; list = XEXP (list, 1))
|
||
{
|
||
rtx insn = XEXP (list, 0);
|
||
rtx pat = PATTERN (insn);
|
||
rtx src = SET_SRC (pat);
|
||
rtx reg = expr->reaching_reg;
|
||
rtx copy, new;
|
||
|
||
/* If we've already copied it, continue. */
|
||
if (expr->reaching_reg == src)
|
||
continue;
|
||
|
||
if (gcse_file)
|
||
{
|
||
fprintf (gcse_file, "PRE: store updated with reaching reg ");
|
||
print_rtl (gcse_file, expr->reaching_reg);
|
||
fprintf (gcse_file, ":\n ");
|
||
print_inline_rtx (gcse_file, insn, 8);
|
||
fprintf (gcse_file, "\n");
|
||
}
|
||
|
||
copy = gen_move_insn ( reg, copy_rtx (SET_SRC (pat)));
|
||
new = emit_insn_before (copy, insn);
|
||
record_one_set (REGNO (reg), new);
|
||
SET_SRC (pat) = reg;
|
||
|
||
/* un-recognize this pattern since it's probably different now. */
|
||
INSN_CODE (insn) = -1;
|
||
gcse_create_count++;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Store motion code. */
|
||
|
||
#define ANTIC_STORE_LIST(x) ((x)->loads)
|
||
#define AVAIL_STORE_LIST(x) ((x)->stores)
|
||
#define LAST_AVAIL_CHECK_FAILURE(x) ((x)->reaching_reg)
|
||
|
||
/* This is used to communicate the target bitvector we want to use in the
|
||
reg_set_info routine when called via the note_stores mechanism. */
|
||
static int * regvec;
|
||
|
||
/* And current insn, for the same routine. */
|
||
static rtx compute_store_table_current_insn;
|
||
|
||
/* Used in computing the reverse edge graph bit vectors. */
|
||
static sbitmap * st_antloc;
|
||
|
||
/* Global holding the number of store expressions we are dealing with. */
|
||
static int num_stores;
|
||
|
||
/* Checks to set if we need to mark a register set. Called from
|
||
note_stores. */
|
||
|
||
static void
|
||
reg_set_info (rtx dest, rtx setter ATTRIBUTE_UNUSED,
|
||
void *data)
|
||
{
|
||
sbitmap bb_reg = data;
|
||
|
||
if (GET_CODE (dest) == SUBREG)
|
||
dest = SUBREG_REG (dest);
|
||
|
||
if (GET_CODE (dest) == REG)
|
||
{
|
||
regvec[REGNO (dest)] = INSN_UID (compute_store_table_current_insn);
|
||
if (bb_reg)
|
||
SET_BIT (bb_reg, REGNO (dest));
|
||
}
|
||
}
|
||
|
||
/* Clear any mark that says that this insn sets dest. Called from
|
||
note_stores. */
|
||
|
||
static void
|
||
reg_clear_last_set (rtx dest, rtx setter ATTRIBUTE_UNUSED,
|
||
void *data)
|
||
{
|
||
int *dead_vec = data;
|
||
|
||
if (GET_CODE (dest) == SUBREG)
|
||
dest = SUBREG_REG (dest);
|
||
|
||
if (GET_CODE (dest) == REG &&
|
||
dead_vec[REGNO (dest)] == INSN_UID (compute_store_table_current_insn))
|
||
dead_vec[REGNO (dest)] = 0;
|
||
}
|
||
|
||
/* Return zero if some of the registers in list X are killed
|
||
due to set of registers in bitmap REGS_SET. */
|
||
|
||
static bool
|
||
store_ops_ok (rtx x, int *regs_set)
|
||
{
|
||
rtx reg;
|
||
|
||
for (; x; x = XEXP (x, 1))
|
||
{
|
||
reg = XEXP (x, 0);
|
||
if (regs_set[REGNO(reg)])
|
||
return false;
|
||
}
|
||
|
||
return true;
|
||
}
|
||
|
||
/* Returns a list of registers mentioned in X. */
|
||
static rtx
|
||
extract_mentioned_regs (rtx x)
|
||
{
|
||
return extract_mentioned_regs_helper (x, NULL_RTX);
|
||
}
|
||
|
||
/* Helper for extract_mentioned_regs; ACCUM is used to accumulate used
|
||
registers. */
|
||
static rtx
|
||
extract_mentioned_regs_helper (rtx x, rtx accum)
|
||
{
|
||
int i;
|
||
enum rtx_code code;
|
||
const char * fmt;
|
||
|
||
/* Repeat is used to turn tail-recursion into iteration. */
|
||
repeat:
|
||
|
||
if (x == 0)
|
||
return accum;
|
||
|
||
code = GET_CODE (x);
|
||
switch (code)
|
||
{
|
||
case REG:
|
||
return alloc_EXPR_LIST (0, x, accum);
|
||
|
||
case MEM:
|
||
x = XEXP (x, 0);
|
||
goto repeat;
|
||
|
||
case PRE_DEC:
|
||
case PRE_INC:
|
||
case POST_DEC:
|
||
case POST_INC:
|
||
/* We do not run this function with arguments having side effects. */
|
||
abort ();
|
||
|
||
case PC:
|
||
case CC0: /*FIXME*/
|
||
case CONST:
|
||
case CONST_INT:
|
||
case CONST_DOUBLE:
|
||
case CONST_VECTOR:
|
||
case SYMBOL_REF:
|
||
case LABEL_REF:
|
||
case ADDR_VEC:
|
||
case ADDR_DIFF_VEC:
|
||
return accum;
|
||
|
||
default:
|
||
break;
|
||
}
|
||
|
||
i = GET_RTX_LENGTH (code) - 1;
|
||
fmt = GET_RTX_FORMAT (code);
|
||
|
||
for (; i >= 0; i--)
|
||
{
|
||
if (fmt[i] == 'e')
|
||
{
|
||
rtx tem = XEXP (x, i);
|
||
|
||
/* If we are about to do the last recursive call
|
||
needed at this level, change it into iteration. */
|
||
if (i == 0)
|
||
{
|
||
x = tem;
|
||
goto repeat;
|
||
}
|
||
|
||
accum = extract_mentioned_regs_helper (tem, accum);
|
||
}
|
||
else if (fmt[i] == 'E')
|
||
{
|
||
int j;
|
||
|
||
for (j = 0; j < XVECLEN (x, i); j++)
|
||
accum = extract_mentioned_regs_helper (XVECEXP (x, i, j), accum);
|
||
}
|
||
}
|
||
|
||
return accum;
|
||
}
|
||
|
||
/* Determine whether INSN is MEM store pattern that we will consider moving.
|
||
REGS_SET_BEFORE is bitmap of registers set before (and including) the
|
||
current insn, REGS_SET_AFTER is bitmap of registers set after (and
|
||
including) the insn in this basic block. We must be passing through BB from
|
||
head to end, as we are using this fact to speed things up.
|
||
|
||
The results are stored this way:
|
||
|
||
-- the first anticipatable expression is added into ANTIC_STORE_LIST
|
||
-- if the processed expression is not anticipatable, NULL_RTX is added
|
||
there instead, so that we can use it as indicator that no further
|
||
expression of this type may be anticipatable
|
||
-- if the expression is available, it is added as head of AVAIL_STORE_LIST;
|
||
consequently, all of them but this head are dead and may be deleted.
|
||
-- if the expression is not available, the insn due to that it fails to be
|
||
available is stored in reaching_reg.
|
||
|
||
The things are complicated a bit by fact that there already may be stores
|
||
to the same MEM from other blocks; also caller must take care of the
|
||
necessary cleanup of the temporary markers after end of the basic block.
|
||
*/
|
||
|
||
static void
|
||
find_moveable_store (rtx insn, int *regs_set_before, int *regs_set_after)
|
||
{
|
||
struct ls_expr * ptr;
|
||
rtx dest, set, tmp;
|
||
int check_anticipatable, check_available;
|
||
basic_block bb = BLOCK_FOR_INSN (insn);
|
||
|
||
set = single_set (insn);
|
||
if (!set)
|
||
return;
|
||
|
||
dest = SET_DEST (set);
|
||
|
||
if (GET_CODE (dest) != MEM || MEM_VOLATILE_P (dest)
|
||
|| GET_MODE (dest) == BLKmode)
|
||
return;
|
||
|
||
if (side_effects_p (dest))
|
||
return;
|
||
|
||
/* If we are handling exceptions, we must be careful with memory references
|
||
that may trap. If we are not, the behavior is undefined, so we may just
|
||
continue. */
|
||
if (flag_non_call_exceptions && may_trap_p (dest))
|
||
return;
|
||
|
||
ptr = ldst_entry (dest);
|
||
if (!ptr->pattern_regs)
|
||
ptr->pattern_regs = extract_mentioned_regs (dest);
|
||
|
||
/* Do not check for anticipatability if we either found one anticipatable
|
||
store already, or tested for one and found out that it was killed. */
|
||
check_anticipatable = 0;
|
||
if (!ANTIC_STORE_LIST (ptr))
|
||
check_anticipatable = 1;
|
||
else
|
||
{
|
||
tmp = XEXP (ANTIC_STORE_LIST (ptr), 0);
|
||
if (tmp != NULL_RTX
|
||
&& BLOCK_FOR_INSN (tmp) != bb)
|
||
check_anticipatable = 1;
|
||
}
|
||
if (check_anticipatable)
|
||
{
|
||
if (store_killed_before (dest, ptr->pattern_regs, insn, bb, regs_set_before))
|
||
tmp = NULL_RTX;
|
||
else
|
||
tmp = insn;
|
||
ANTIC_STORE_LIST (ptr) = alloc_INSN_LIST (tmp,
|
||
ANTIC_STORE_LIST (ptr));
|
||
}
|
||
|
||
/* It is not necessary to check whether store is available if we did
|
||
it successfully before; if we failed before, do not bother to check
|
||
until we reach the insn that caused us to fail. */
|
||
check_available = 0;
|
||
if (!AVAIL_STORE_LIST (ptr))
|
||
check_available = 1;
|
||
else
|
||
{
|
||
tmp = XEXP (AVAIL_STORE_LIST (ptr), 0);
|
||
if (BLOCK_FOR_INSN (tmp) != bb)
|
||
check_available = 1;
|
||
}
|
||
if (check_available)
|
||
{
|
||
/* Check that we have already reached the insn at that the check
|
||
failed last time. */
|
||
if (LAST_AVAIL_CHECK_FAILURE (ptr))
|
||
{
|
||
for (tmp = BB_END (bb);
|
||
tmp != insn && tmp != LAST_AVAIL_CHECK_FAILURE (ptr);
|
||
tmp = PREV_INSN (tmp))
|
||
continue;
|
||
if (tmp == insn)
|
||
check_available = 0;
|
||
}
|
||
else
|
||
check_available = store_killed_after (dest, ptr->pattern_regs, insn,
|
||
bb, regs_set_after,
|
||
&LAST_AVAIL_CHECK_FAILURE (ptr));
|
||
}
|
||
if (!check_available)
|
||
AVAIL_STORE_LIST (ptr) = alloc_INSN_LIST (insn, AVAIL_STORE_LIST (ptr));
|
||
}
|
||
|
||
/* Find available and anticipatable stores. */
|
||
|
||
static int
|
||
compute_store_table (void)
|
||
{
|
||
int ret;
|
||
basic_block bb;
|
||
unsigned regno;
|
||
rtx insn, pat, tmp;
|
||
int *last_set_in, *already_set;
|
||
struct ls_expr * ptr, **prev_next_ptr_ptr;
|
||
|
||
max_gcse_regno = max_reg_num ();
|
||
|
||
reg_set_in_block = sbitmap_vector_alloc (last_basic_block,
|
||
max_gcse_regno);
|
||
sbitmap_vector_zero (reg_set_in_block, last_basic_block);
|
||
pre_ldst_mems = 0;
|
||
last_set_in = xcalloc (max_gcse_regno, sizeof (int));
|
||
already_set = xmalloc (sizeof (int) * max_gcse_regno);
|
||
|
||
/* Find all the stores we care about. */
|
||
FOR_EACH_BB (bb)
|
||
{
|
||
/* First compute the registers set in this block. */
|
||
regvec = last_set_in;
|
||
|
||
for (insn = BB_HEAD (bb);
|
||
insn != NEXT_INSN (BB_END (bb));
|
||
insn = NEXT_INSN (insn))
|
||
{
|
||
if (! INSN_P (insn))
|
||
continue;
|
||
|
||
if (GET_CODE (insn) == CALL_INSN)
|
||
{
|
||
bool clobbers_all = false;
|
||
#ifdef NON_SAVING_SETJMP
|
||
if (NON_SAVING_SETJMP
|
||
&& find_reg_note (insn, REG_SETJMP, NULL_RTX))
|
||
clobbers_all = true;
|
||
#endif
|
||
|
||
for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
|
||
if (clobbers_all
|
||
|| TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
|
||
{
|
||
last_set_in[regno] = INSN_UID (insn);
|
||
SET_BIT (reg_set_in_block[bb->index], regno);
|
||
}
|
||
}
|
||
|
||
pat = PATTERN (insn);
|
||
compute_store_table_current_insn = insn;
|
||
note_stores (pat, reg_set_info, reg_set_in_block[bb->index]);
|
||
}
|
||
|
||
/* Now find the stores. */
|
||
memset (already_set, 0, sizeof (int) * max_gcse_regno);
|
||
regvec = already_set;
|
||
for (insn = BB_HEAD (bb);
|
||
insn != NEXT_INSN (BB_END (bb));
|
||
insn = NEXT_INSN (insn))
|
||
{
|
||
if (! INSN_P (insn))
|
||
continue;
|
||
|
||
if (GET_CODE (insn) == CALL_INSN)
|
||
{
|
||
bool clobbers_all = false;
|
||
#ifdef NON_SAVING_SETJMP
|
||
if (NON_SAVING_SETJMP
|
||
&& find_reg_note (insn, REG_SETJMP, NULL_RTX))
|
||
clobbers_all = true;
|
||
#endif
|
||
|
||
for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
|
||
if (clobbers_all
|
||
|| TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
|
||
already_set[regno] = 1;
|
||
}
|
||
|
||
pat = PATTERN (insn);
|
||
note_stores (pat, reg_set_info, NULL);
|
||
|
||
/* Now that we've marked regs, look for stores. */
|
||
find_moveable_store (insn, already_set, last_set_in);
|
||
|
||
/* Unmark regs that are no longer set. */
|
||
compute_store_table_current_insn = insn;
|
||
note_stores (pat, reg_clear_last_set, last_set_in);
|
||
if (GET_CODE (insn) == CALL_INSN)
|
||
{
|
||
bool clobbers_all = false;
|
||
#ifdef NON_SAVING_SETJMP
|
||
if (NON_SAVING_SETJMP
|
||
&& find_reg_note (insn, REG_SETJMP, NULL_RTX))
|
||
clobbers_all = true;
|
||
#endif
|
||
|
||
for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
|
||
if ((clobbers_all
|
||
|| TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
|
||
&& last_set_in[regno] == INSN_UID (insn))
|
||
last_set_in[regno] = 0;
|
||
}
|
||
}
|
||
|
||
#ifdef ENABLE_CHECKING
|
||
/* last_set_in should now be all-zero. */
|
||
for (regno = 0; regno < max_gcse_regno; regno++)
|
||
if (last_set_in[regno] != 0)
|
||
abort ();
|
||
#endif
|
||
|
||
/* Clear temporary marks. */
|
||
for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
|
||
{
|
||
LAST_AVAIL_CHECK_FAILURE(ptr) = NULL_RTX;
|
||
if (ANTIC_STORE_LIST (ptr)
|
||
&& (tmp = XEXP (ANTIC_STORE_LIST (ptr), 0)) == NULL_RTX)
|
||
ANTIC_STORE_LIST (ptr) = XEXP (ANTIC_STORE_LIST (ptr), 1);
|
||
}
|
||
}
|
||
|
||
/* Remove the stores that are not available anywhere, as there will
|
||
be no opportunity to optimize them. */
|
||
for (ptr = pre_ldst_mems, prev_next_ptr_ptr = &pre_ldst_mems;
|
||
ptr != NULL;
|
||
ptr = *prev_next_ptr_ptr)
|
||
{
|
||
if (!AVAIL_STORE_LIST (ptr))
|
||
{
|
||
*prev_next_ptr_ptr = ptr->next;
|
||
free_ldst_entry (ptr);
|
||
}
|
||
else
|
||
prev_next_ptr_ptr = &ptr->next;
|
||
}
|
||
|
||
ret = enumerate_ldsts ();
|
||
|
||
if (gcse_file)
|
||
{
|
||
fprintf (gcse_file, "ST_avail and ST_antic (shown under loads..)\n");
|
||
print_ldst_list (gcse_file);
|
||
}
|
||
|
||
free (last_set_in);
|
||
free (already_set);
|
||
return ret;
|
||
}
|
||
|
||
/* Check to see if the load X is aliased with STORE_PATTERN.
|
||
AFTER is true if we are checking the case when STORE_PATTERN occurs
|
||
after the X. */
|
||
|
||
static bool
|
||
load_kills_store (rtx x, rtx store_pattern, int after)
|
||
{
|
||
if (after)
|
||
return anti_dependence (x, store_pattern);
|
||
else
|
||
return true_dependence (store_pattern, GET_MODE (store_pattern), x,
|
||
rtx_addr_varies_p);
|
||
}
|
||
|
||
/* Go through the entire insn X, looking for any loads which might alias
|
||
STORE_PATTERN. Return true if found.
|
||
AFTER is true if we are checking the case when STORE_PATTERN occurs
|
||
after the insn X. */
|
||
|
||
static bool
|
||
find_loads (rtx x, rtx store_pattern, int after)
|
||
{
|
||
const char * fmt;
|
||
int i, j;
|
||
int ret = false;
|
||
|
||
if (!x)
|
||
return false;
|
||
|
||
if (GET_CODE (x) == SET)
|
||
x = SET_SRC (x);
|
||
|
||
if (GET_CODE (x) == MEM)
|
||
{
|
||
if (load_kills_store (x, store_pattern, after))
|
||
return true;
|
||
}
|
||
|
||
/* Recursively process the insn. */
|
||
fmt = GET_RTX_FORMAT (GET_CODE (x));
|
||
|
||
for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0 && !ret; i--)
|
||
{
|
||
if (fmt[i] == 'e')
|
||
ret |= find_loads (XEXP (x, i), store_pattern, after);
|
||
else if (fmt[i] == 'E')
|
||
for (j = XVECLEN (x, i) - 1; j >= 0; j--)
|
||
ret |= find_loads (XVECEXP (x, i, j), store_pattern, after);
|
||
}
|
||
return ret;
|
||
}
|
||
|
||
/* Check if INSN kills the store pattern X (is aliased with it).
|
||
AFTER is true if we are checking the case when store X occurs
|
||
after the insn. Return true if it it does. */
|
||
|
||
static bool
|
||
store_killed_in_insn (rtx x, rtx x_regs, rtx insn, int after)
|
||
{
|
||
rtx reg, base, note;
|
||
|
||
if (!INSN_P (insn))
|
||
return false;
|
||
|
||
if (GET_CODE (insn) == CALL_INSN)
|
||
{
|
||
/* A normal or pure call might read from pattern,
|
||
but a const call will not. */
|
||
if (! CONST_OR_PURE_CALL_P (insn) || pure_call_p (insn))
|
||
return true;
|
||
|
||
/* But even a const call reads its parameters. Check whether the
|
||
base of some of registers used in mem is stack pointer. */
|
||
for (reg = x_regs; reg; reg = XEXP (reg, 1))
|
||
{
|
||
base = find_base_term (XEXP (reg, 0));
|
||
if (!base
|
||
|| (GET_CODE (base) == ADDRESS
|
||
&& GET_MODE (base) == Pmode
|
||
&& XEXP (base, 0) == stack_pointer_rtx))
|
||
return true;
|
||
}
|
||
|
||
return false;
|
||
}
|
||
|
||
if (GET_CODE (PATTERN (insn)) == SET)
|
||
{
|
||
rtx pat = PATTERN (insn);
|
||
rtx dest = SET_DEST (pat);
|
||
|
||
if (GET_CODE (dest) == SIGN_EXTRACT
|
||
|| GET_CODE (dest) == ZERO_EXTRACT)
|
||
dest = XEXP (dest, 0);
|
||
|
||
/* Check for memory stores to aliased objects. */
|
||
if (GET_CODE (dest) == MEM
|
||
&& !expr_equiv_p (dest, x))
|
||
{
|
||
if (after)
|
||
{
|
||
if (output_dependence (dest, x))
|
||
return true;
|
||
}
|
||
else
|
||
{
|
||
if (output_dependence (x, dest))
|
||
return true;
|
||
}
|
||
}
|
||
if (find_loads (SET_SRC (pat), x, after))
|
||
return true;
|
||
}
|
||
else if (find_loads (PATTERN (insn), x, after))
|
||
return true;
|
||
|
||
/* If this insn has a REG_EQUAL or REG_EQUIV note referencing a memory
|
||
location aliased with X, then this insn kills X. */
|
||
note = find_reg_equal_equiv_note (insn);
|
||
if (! note)
|
||
return false;
|
||
note = XEXP (note, 0);
|
||
|
||
/* However, if the note represents a must alias rather than a may
|
||
alias relationship, then it does not kill X. */
|
||
if (expr_equiv_p (note, x))
|
||
return false;
|
||
|
||
/* See if there are any aliased loads in the note. */
|
||
return find_loads (note, x, after);
|
||
}
|
||
|
||
/* Returns true if the expression X is loaded or clobbered on or after INSN
|
||
within basic block BB. REGS_SET_AFTER is bitmap of registers set in
|
||
or after the insn. X_REGS is list of registers mentioned in X. If the store
|
||
is killed, return the last insn in that it occurs in FAIL_INSN. */
|
||
|
||
static bool
|
||
store_killed_after (rtx x, rtx x_regs, rtx insn, basic_block bb,
|
||
int *regs_set_after, rtx *fail_insn)
|
||
{
|
||
rtx last = BB_END (bb), act;
|
||
|
||
if (!store_ops_ok (x_regs, regs_set_after))
|
||
{
|
||
/* We do not know where it will happen. */
|
||
if (fail_insn)
|
||
*fail_insn = NULL_RTX;
|
||
return true;
|
||
}
|
||
|
||
/* Scan from the end, so that fail_insn is determined correctly. */
|
||
for (act = last; act != PREV_INSN (insn); act = PREV_INSN (act))
|
||
if (store_killed_in_insn (x, x_regs, act, false))
|
||
{
|
||
if (fail_insn)
|
||
*fail_insn = act;
|
||
return true;
|
||
}
|
||
|
||
return false;
|
||
}
|
||
|
||
/* Returns true if the expression X is loaded or clobbered on or before INSN
|
||
within basic block BB. X_REGS is list of registers mentioned in X.
|
||
REGS_SET_BEFORE is bitmap of registers set before or in this insn. */
|
||
static bool
|
||
store_killed_before (rtx x, rtx x_regs, rtx insn, basic_block bb,
|
||
int *regs_set_before)
|
||
{
|
||
rtx first = BB_HEAD (bb);
|
||
|
||
if (!store_ops_ok (x_regs, regs_set_before))
|
||
return true;
|
||
|
||
for ( ; insn != PREV_INSN (first); insn = PREV_INSN (insn))
|
||
if (store_killed_in_insn (x, x_regs, insn, true))
|
||
return true;
|
||
|
||
return false;
|
||
}
|
||
|
||
/* Fill in available, anticipatable, transparent and kill vectors in
|
||
STORE_DATA, based on lists of available and anticipatable stores. */
|
||
static void
|
||
build_store_vectors (void)
|
||
{
|
||
basic_block bb;
|
||
int *regs_set_in_block;
|
||
rtx insn, st;
|
||
struct ls_expr * ptr;
|
||
unsigned regno;
|
||
|
||
/* Build the gen_vector. This is any store in the table which is not killed
|
||
by aliasing later in its block. */
|
||
ae_gen = sbitmap_vector_alloc (last_basic_block, num_stores);
|
||
sbitmap_vector_zero (ae_gen, last_basic_block);
|
||
|
||
st_antloc = sbitmap_vector_alloc (last_basic_block, num_stores);
|
||
sbitmap_vector_zero (st_antloc, last_basic_block);
|
||
|
||
for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
|
||
{
|
||
for (st = AVAIL_STORE_LIST (ptr); st != NULL; st = XEXP (st, 1))
|
||
{
|
||
insn = XEXP (st, 0);
|
||
bb = BLOCK_FOR_INSN (insn);
|
||
|
||
/* If we've already seen an available expression in this block,
|
||
we can delete this one (It occurs earlier in the block). We'll
|
||
copy the SRC expression to an unused register in case there
|
||
are any side effects. */
|
||
if (TEST_BIT (ae_gen[bb->index], ptr->index))
|
||
{
|
||
rtx r = gen_reg_rtx (GET_MODE (ptr->pattern));
|
||
if (gcse_file)
|
||
fprintf (gcse_file, "Removing redundant store:\n");
|
||
replace_store_insn (r, XEXP (st, 0), bb, ptr);
|
||
continue;
|
||
}
|
||
SET_BIT (ae_gen[bb->index], ptr->index);
|
||
}
|
||
|
||
for (st = ANTIC_STORE_LIST (ptr); st != NULL; st = XEXP (st, 1))
|
||
{
|
||
insn = XEXP (st, 0);
|
||
bb = BLOCK_FOR_INSN (insn);
|
||
SET_BIT (st_antloc[bb->index], ptr->index);
|
||
}
|
||
}
|
||
|
||
ae_kill = sbitmap_vector_alloc (last_basic_block, num_stores);
|
||
sbitmap_vector_zero (ae_kill, last_basic_block);
|
||
|
||
transp = sbitmap_vector_alloc (last_basic_block, num_stores);
|
||
sbitmap_vector_zero (transp, last_basic_block);
|
||
regs_set_in_block = xmalloc (sizeof (int) * max_gcse_regno);
|
||
|
||
FOR_EACH_BB (bb)
|
||
{
|
||
for (regno = 0; regno < max_gcse_regno; regno++)
|
||
regs_set_in_block[regno] = TEST_BIT (reg_set_in_block[bb->index], regno);
|
||
|
||
for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
|
||
{
|
||
if (store_killed_after (ptr->pattern, ptr->pattern_regs, BB_HEAD (bb),
|
||
bb, regs_set_in_block, NULL))
|
||
{
|
||
/* It should not be necessary to consider the expression
|
||
killed if it is both anticipatable and available. */
|
||
if (!TEST_BIT (st_antloc[bb->index], ptr->index)
|
||
|| !TEST_BIT (ae_gen[bb->index], ptr->index))
|
||
SET_BIT (ae_kill[bb->index], ptr->index);
|
||
}
|
||
else
|
||
SET_BIT (transp[bb->index], ptr->index);
|
||
}
|
||
}
|
||
|
||
free (regs_set_in_block);
|
||
|
||
if (gcse_file)
|
||
{
|
||
dump_sbitmap_vector (gcse_file, "st_antloc", "", st_antloc, last_basic_block);
|
||
dump_sbitmap_vector (gcse_file, "st_kill", "", ae_kill, last_basic_block);
|
||
dump_sbitmap_vector (gcse_file, "Transpt", "", transp, last_basic_block);
|
||
dump_sbitmap_vector (gcse_file, "st_avloc", "", ae_gen, last_basic_block);
|
||
}
|
||
}
|
||
|
||
/* Insert an instruction at the beginning of a basic block, and update
|
||
the BB_HEAD if needed. */
|
||
|
||
static void
|
||
insert_insn_start_bb (rtx insn, basic_block bb)
|
||
{
|
||
/* Insert at start of successor block. */
|
||
rtx prev = PREV_INSN (BB_HEAD (bb));
|
||
rtx before = BB_HEAD (bb);
|
||
while (before != 0)
|
||
{
|
||
if (GET_CODE (before) != CODE_LABEL
|
||
&& (GET_CODE (before) != NOTE
|
||
|| NOTE_LINE_NUMBER (before) != NOTE_INSN_BASIC_BLOCK))
|
||
break;
|
||
prev = before;
|
||
if (prev == BB_END (bb))
|
||
break;
|
||
before = NEXT_INSN (before);
|
||
}
|
||
|
||
insn = emit_insn_after_noloc (insn, prev);
|
||
|
||
if (gcse_file)
|
||
{
|
||
fprintf (gcse_file, "STORE_MOTION insert store at start of BB %d:\n",
|
||
bb->index);
|
||
print_inline_rtx (gcse_file, insn, 6);
|
||
fprintf (gcse_file, "\n");
|
||
}
|
||
}
|
||
|
||
/* This routine will insert a store on an edge. EXPR is the ldst entry for
|
||
the memory reference, and E is the edge to insert it on. Returns nonzero
|
||
if an edge insertion was performed. */
|
||
|
||
static int
|
||
insert_store (struct ls_expr * expr, edge e)
|
||
{
|
||
rtx reg, insn;
|
||
basic_block bb;
|
||
edge tmp;
|
||
|
||
/* We did all the deleted before this insert, so if we didn't delete a
|
||
store, then we haven't set the reaching reg yet either. */
|
||
if (expr->reaching_reg == NULL_RTX)
|
||
return 0;
|
||
|
||
if (e->flags & EDGE_FAKE)
|
||
return 0;
|
||
|
||
reg = expr->reaching_reg;
|
||
insn = gen_move_insn (copy_rtx (expr->pattern), reg);
|
||
|
||
/* If we are inserting this expression on ALL predecessor edges of a BB,
|
||
insert it at the start of the BB, and reset the insert bits on the other
|
||
edges so we don't try to insert it on the other edges. */
|
||
bb = e->dest;
|
||
for (tmp = e->dest->pred; tmp ; tmp = tmp->pred_next)
|
||
if (!(tmp->flags & EDGE_FAKE))
|
||
{
|
||
int index = EDGE_INDEX (edge_list, tmp->src, tmp->dest);
|
||
if (index == EDGE_INDEX_NO_EDGE)
|
||
abort ();
|
||
if (! TEST_BIT (pre_insert_map[index], expr->index))
|
||
break;
|
||
}
|
||
|
||
/* If tmp is NULL, we found an insertion on every edge, blank the
|
||
insertion vector for these edges, and insert at the start of the BB. */
|
||
if (!tmp && bb != EXIT_BLOCK_PTR)
|
||
{
|
||
for (tmp = e->dest->pred; tmp ; tmp = tmp->pred_next)
|
||
{
|
||
int index = EDGE_INDEX (edge_list, tmp->src, tmp->dest);
|
||
RESET_BIT (pre_insert_map[index], expr->index);
|
||
}
|
||
insert_insn_start_bb (insn, bb);
|
||
return 0;
|
||
}
|
||
|
||
/* We can't insert on this edge, so we'll insert at the head of the
|
||
successors block. See Morgan, sec 10.5. */
|
||
if ((e->flags & EDGE_ABNORMAL) == EDGE_ABNORMAL)
|
||
{
|
||
insert_insn_start_bb (insn, bb);
|
||
return 0;
|
||
}
|
||
|
||
insert_insn_on_edge (insn, e);
|
||
|
||
if (gcse_file)
|
||
{
|
||
fprintf (gcse_file, "STORE_MOTION insert insn on edge (%d, %d):\n",
|
||
e->src->index, e->dest->index);
|
||
print_inline_rtx (gcse_file, insn, 6);
|
||
fprintf (gcse_file, "\n");
|
||
}
|
||
|
||
return 1;
|
||
}
|
||
|
||
/* Remove any REG_EQUAL or REG_EQUIV notes containing a reference to the
|
||
memory location in SMEXPR set in basic block BB.
|
||
|
||
This could be rather expensive. */
|
||
|
||
static void
|
||
remove_reachable_equiv_notes (basic_block bb, struct ls_expr *smexpr)
|
||
{
|
||
edge *stack = xmalloc (sizeof (edge) * n_basic_blocks), act;
|
||
sbitmap visited = sbitmap_alloc (last_basic_block);
|
||
int stack_top = 0;
|
||
rtx last, insn, note;
|
||
rtx mem = smexpr->pattern;
|
||
|
||
sbitmap_zero (visited);
|
||
act = bb->succ;
|
||
|
||
while (1)
|
||
{
|
||
if (!act)
|
||
{
|
||
if (!stack_top)
|
||
{
|
||
free (stack);
|
||
sbitmap_free (visited);
|
||
return;
|
||
}
|
||
act = stack[--stack_top];
|
||
}
|
||
bb = act->dest;
|
||
|
||
/* We used to continue the loop without scanning this block if the
|
||
store expression was killed in this block. That is wrong as
|
||
we could have had a REG_EQUAL note with the store expression
|
||
appear in the block before the insn which killed the store
|
||
expression and that REG_EQUAL note needs to be removed as it
|
||
is invalid. */
|
||
if (bb == EXIT_BLOCK_PTR
|
||
|| TEST_BIT (visited, bb->index))
|
||
{
|
||
act = act->succ_next;
|
||
continue;
|
||
}
|
||
SET_BIT (visited, bb->index);
|
||
|
||
if (TEST_BIT (st_antloc[bb->index], smexpr->index))
|
||
{
|
||
for (last = ANTIC_STORE_LIST (smexpr);
|
||
BLOCK_FOR_INSN (XEXP (last, 0)) != bb;
|
||
last = XEXP (last, 1))
|
||
continue;
|
||
last = XEXP (last, 0);
|
||
}
|
||
else
|
||
last = NEXT_INSN (BB_END (bb));
|
||
|
||
for (insn = BB_HEAD (bb); insn != last; insn = NEXT_INSN (insn))
|
||
if (INSN_P (insn))
|
||
{
|
||
note = find_reg_equal_equiv_note (insn);
|
||
if (!note || !expr_equiv_p (XEXP (note, 0), mem))
|
||
continue;
|
||
|
||
if (gcse_file)
|
||
fprintf (gcse_file, "STORE_MOTION drop REG_EQUAL note at insn %d:\n",
|
||
INSN_UID (insn));
|
||
remove_note (insn, note);
|
||
}
|
||
act = act->succ_next;
|
||
if (bb->succ)
|
||
{
|
||
if (act)
|
||
stack[stack_top++] = act;
|
||
act = bb->succ;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* This routine will replace a store with a SET to a specified register. */
|
||
|
||
static void
|
||
replace_store_insn (rtx reg, rtx del, basic_block bb, struct ls_expr *smexpr)
|
||
{
|
||
rtx insn, mem, note, set, ptr, pair;
|
||
|
||
mem = smexpr->pattern;
|
||
insn = gen_move_insn (reg, SET_SRC (single_set (del)));
|
||
insn = emit_insn_after (insn, del);
|
||
|
||
if (gcse_file)
|
||
{
|
||
fprintf (gcse_file,
|
||
"STORE_MOTION delete insn in BB %d:\n ", bb->index);
|
||
print_inline_rtx (gcse_file, del, 6);
|
||
fprintf (gcse_file, "\nSTORE MOTION replaced with insn:\n ");
|
||
print_inline_rtx (gcse_file, insn, 6);
|
||
fprintf (gcse_file, "\n");
|
||
}
|
||
|
||
for (ptr = ANTIC_STORE_LIST (smexpr); ptr; ptr = XEXP (ptr, 1))
|
||
if (XEXP (ptr, 0) == del)
|
||
{
|
||
XEXP (ptr, 0) = insn;
|
||
break;
|
||
}
|
||
|
||
/* Move the notes from the deleted insn to its replacement, and patch
|
||
up the LIBCALL notes. */
|
||
REG_NOTES (insn) = REG_NOTES (del);
|
||
|
||
note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
|
||
if (note)
|
||
{
|
||
pair = XEXP (note, 0);
|
||
note = find_reg_note (pair, REG_LIBCALL, NULL_RTX);
|
||
XEXP (note, 0) = insn;
|
||
}
|
||
note = find_reg_note (insn, REG_LIBCALL, NULL_RTX);
|
||
if (note)
|
||
{
|
||
pair = XEXP (note, 0);
|
||
note = find_reg_note (pair, REG_RETVAL, NULL_RTX);
|
||
XEXP (note, 0) = insn;
|
||
}
|
||
|
||
delete_insn (del);
|
||
|
||
/* Now we must handle REG_EQUAL notes whose contents is equal to the mem;
|
||
they are no longer accurate provided that they are reached by this
|
||
definition, so drop them. */
|
||
for (; insn != NEXT_INSN (BB_END (bb)); insn = NEXT_INSN (insn))
|
||
if (INSN_P (insn))
|
||
{
|
||
set = single_set (insn);
|
||
if (!set)
|
||
continue;
|
||
if (expr_equiv_p (SET_DEST (set), mem))
|
||
return;
|
||
note = find_reg_equal_equiv_note (insn);
|
||
if (!note || !expr_equiv_p (XEXP (note, 0), mem))
|
||
continue;
|
||
|
||
if (gcse_file)
|
||
fprintf (gcse_file, "STORE_MOTION drop REG_EQUAL note at insn %d:\n",
|
||
INSN_UID (insn));
|
||
remove_note (insn, note);
|
||
}
|
||
remove_reachable_equiv_notes (bb, smexpr);
|
||
}
|
||
|
||
|
||
/* Delete a store, but copy the value that would have been stored into
|
||
the reaching_reg for later storing. */
|
||
|
||
static void
|
||
delete_store (struct ls_expr * expr, basic_block bb)
|
||
{
|
||
rtx reg, i, del;
|
||
|
||
if (expr->reaching_reg == NULL_RTX)
|
||
expr->reaching_reg = gen_reg_rtx (GET_MODE (expr->pattern));
|
||
|
||
reg = expr->reaching_reg;
|
||
|
||
for (i = AVAIL_STORE_LIST (expr); i; i = XEXP (i, 1))
|
||
{
|
||
del = XEXP (i, 0);
|
||
if (BLOCK_FOR_INSN (del) == bb)
|
||
{
|
||
/* We know there is only one since we deleted redundant
|
||
ones during the available computation. */
|
||
replace_store_insn (reg, del, bb, expr);
|
||
break;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Free memory used by store motion. */
|
||
|
||
static void
|
||
free_store_memory (void)
|
||
{
|
||
free_ldst_mems ();
|
||
|
||
if (ae_gen)
|
||
sbitmap_vector_free (ae_gen);
|
||
if (ae_kill)
|
||
sbitmap_vector_free (ae_kill);
|
||
if (transp)
|
||
sbitmap_vector_free (transp);
|
||
if (st_antloc)
|
||
sbitmap_vector_free (st_antloc);
|
||
if (pre_insert_map)
|
||
sbitmap_vector_free (pre_insert_map);
|
||
if (pre_delete_map)
|
||
sbitmap_vector_free (pre_delete_map);
|
||
if (reg_set_in_block)
|
||
sbitmap_vector_free (reg_set_in_block);
|
||
|
||
ae_gen = ae_kill = transp = st_antloc = NULL;
|
||
pre_insert_map = pre_delete_map = reg_set_in_block = NULL;
|
||
}
|
||
|
||
/* Perform store motion. Much like gcse, except we move expressions the
|
||
other way by looking at the flowgraph in reverse. */
|
||
|
||
static void
|
||
store_motion (void)
|
||
{
|
||
basic_block bb;
|
||
int x;
|
||
struct ls_expr * ptr;
|
||
int update_flow = 0;
|
||
|
||
if (gcse_file)
|
||
{
|
||
fprintf (gcse_file, "before store motion\n");
|
||
print_rtl (gcse_file, get_insns ());
|
||
}
|
||
|
||
init_alias_analysis ();
|
||
|
||
/* Find all the available and anticipatable stores. */
|
||
num_stores = compute_store_table ();
|
||
if (num_stores == 0)
|
||
{
|
||
sbitmap_vector_free (reg_set_in_block);
|
||
end_alias_analysis ();
|
||
return;
|
||
}
|
||
|
||
/* Now compute kill & transp vectors. */
|
||
build_store_vectors ();
|
||
add_noreturn_fake_exit_edges ();
|
||
connect_infinite_loops_to_exit ();
|
||
|
||
edge_list = pre_edge_rev_lcm (gcse_file, num_stores, transp, ae_gen,
|
||
st_antloc, ae_kill, &pre_insert_map,
|
||
&pre_delete_map);
|
||
|
||
/* Now we want to insert the new stores which are going to be needed. */
|
||
for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
|
||
{
|
||
FOR_EACH_BB (bb)
|
||
if (TEST_BIT (pre_delete_map[bb->index], ptr->index))
|
||
delete_store (ptr, bb);
|
||
|
||
for (x = 0; x < NUM_EDGES (edge_list); x++)
|
||
if (TEST_BIT (pre_insert_map[x], ptr->index))
|
||
update_flow |= insert_store (ptr, INDEX_EDGE (edge_list, x));
|
||
}
|
||
|
||
if (update_flow)
|
||
commit_edge_insertions ();
|
||
|
||
free_store_memory ();
|
||
free_edge_list (edge_list);
|
||
remove_fake_edges ();
|
||
end_alias_analysis ();
|
||
}
|
||
|
||
|
||
/* Entry point for jump bypassing optimization pass. */
|
||
|
||
int
|
||
bypass_jumps (FILE *file)
|
||
{
|
||
int changed;
|
||
|
||
/* We do not construct an accurate cfg in functions which call
|
||
setjmp, so just punt to be safe. */
|
||
if (current_function_calls_setjmp)
|
||
return 0;
|
||
|
||
/* For calling dump_foo fns from gdb. */
|
||
debug_stderr = stderr;
|
||
gcse_file = file;
|
||
|
||
/* Identify the basic block information for this function, including
|
||
successors and predecessors. */
|
||
max_gcse_regno = max_reg_num ();
|
||
|
||
if (file)
|
||
dump_flow_info (file);
|
||
|
||
/* Return if there's nothing to do, or it is too expensive. */
|
||
if (n_basic_blocks <= 1 || is_too_expensive (_ ("jump bypassing disabled")))
|
||
return 0;
|
||
|
||
gcc_obstack_init (&gcse_obstack);
|
||
bytes_used = 0;
|
||
|
||
/* We need alias. */
|
||
init_alias_analysis ();
|
||
|
||
/* Record where pseudo-registers are set. This data is kept accurate
|
||
during each pass. ??? We could also record hard-reg information here
|
||
[since it's unchanging], however it is currently done during hash table
|
||
computation.
|
||
|
||
It may be tempting to compute MEM set information here too, but MEM sets
|
||
will be subject to code motion one day and thus we need to compute
|
||
information about memory sets when we build the hash tables. */
|
||
|
||
alloc_reg_set_mem (max_gcse_regno);
|
||
compute_sets (get_insns ());
|
||
|
||
max_gcse_regno = max_reg_num ();
|
||
alloc_gcse_mem (get_insns ());
|
||
changed = one_cprop_pass (1, 1, 1);
|
||
free_gcse_mem ();
|
||
|
||
if (file)
|
||
{
|
||
fprintf (file, "BYPASS of %s: %d basic blocks, ",
|
||
current_function_name (), n_basic_blocks);
|
||
fprintf (file, "%d bytes\n\n", bytes_used);
|
||
}
|
||
|
||
obstack_free (&gcse_obstack, NULL);
|
||
free_reg_set_mem ();
|
||
|
||
/* We are finished with alias. */
|
||
end_alias_analysis ();
|
||
allocate_reg_info (max_reg_num (), FALSE, FALSE);
|
||
|
||
return changed;
|
||
}
|
||
|
||
/* Return true if the graph is too expensive to optimize. PASS is the
|
||
optimization about to be performed. */
|
||
|
||
static bool
|
||
is_too_expensive (const char *pass)
|
||
{
|
||
/* Trying to perform global optimizations on flow graphs which have
|
||
a high connectivity will take a long time and is unlikely to be
|
||
particularly useful.
|
||
|
||
In normal circumstances a cfg should have about twice as many
|
||
edges as blocks. But we do not want to punish small functions
|
||
which have a couple switch statements. Rather than simply
|
||
threshold the number of blocks, uses something with a more
|
||
graceful degradation. */
|
||
if (n_edges > 20000 + n_basic_blocks * 4)
|
||
{
|
||
if (warn_disabled_optimization)
|
||
warning ("%s: %d basic blocks and %d edges/basic block",
|
||
pass, n_basic_blocks, n_edges / n_basic_blocks);
|
||
|
||
return true;
|
||
}
|
||
|
||
/* If allocating memory for the cprop bitmap would take up too much
|
||
storage it's better just to disable the optimization. */
|
||
if ((n_basic_blocks
|
||
* SBITMAP_SET_SIZE (max_reg_num ())
|
||
* sizeof (SBITMAP_ELT_TYPE)) > MAX_GCSE_MEMORY)
|
||
{
|
||
if (warn_disabled_optimization)
|
||
warning ("%s: %d basic blocks and %d registers",
|
||
pass, n_basic_blocks, max_reg_num ());
|
||
|
||
return true;
|
||
}
|
||
|
||
return false;
|
||
}
|
||
|
||
#include "gt-gcse.h"
|