4759 lines
129 KiB
C
4759 lines
129 KiB
C
/* Global common subexpression elimination
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and global constant/copy propagation for GNU compiler.
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Copyright (C) 1997 Free Software Foundation, Inc.
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This file is part of GNU CC.
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GNU CC is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU CC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU CC; see the file COPYING. If not, write to
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the Free Software Foundation, 59 Temple Place - Suite 330,
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Boston, MA 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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- memory aliasing support
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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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NOTES
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- the classic gcse implementation is kept in for now for comparison
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*/
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/* References searched while implementing this.
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This list will eventually be deleted but I wanted to have a record of it
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for now.
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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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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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xxx
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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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reread
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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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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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yyy
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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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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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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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People wishing to speed up the code here should read xxx, yyy.
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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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/* Must precede rtl.h for FFS. */
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#include "system.h"
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#include "rtl.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 "obstack.h"
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#define obstack_chunk_alloc gmalloc
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#define obstack_chunk_free free
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/* Maximum number of passes to perform. */
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#define MAX_PASSES 1
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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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#define FOLLOW_BACK_EDGES 1
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/* We support two GCSE implementations: Classic GCSE (i.e. Dragon Book)
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and PRE (Partial Redundancy Elimination) GCSE (based on Fred Chow's thesis).
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The default is PRE.
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In either case 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 [only if PRE].
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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). This feature of PRE is disabled here (by not
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propagating dataflow information along back edges) because loop.c has more
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involved (and thus typically better) heuristics for what to move out of
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loops.
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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. Macro MAX_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 seconds 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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When -fclassic-gcse, we perform a classic global CSE pass.
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It is based on the algorithms in the Dragon book, and is based on code
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written by Devor Tevi at Intel.
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The steps for Classic GCSE are:
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1) Build the hash table of expressions we wish to GCSE (expr_hash_table).
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Also recorded are reaching definition "gen" statements (rd_gen)
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2) Compute the reaching definitions (reaching_defs).
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This is a bitmap for each basic block indexed by INSN_CUID that is 1
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for each statement containing a definition that reaches the block.
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3) Compute the available expressions (ae_in).
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This is a bitmap for each basic block indexed by expression number
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that is 1 for each expression that is available at the beginning of
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the block.
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4) Perform GCSE.
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This is done by scanning each instruction looking for sets of the form
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(set (pseudo-reg) (expression)) and checking if `expression' is in the
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hash table. If it is, and if the expression is available, and if only
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one computation of the expression reaches the instruction, we substitute
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the expression for a register containing its value. If there is no
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such register, but the expression is expensive enough we create an
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instruction to copy the result of the expression into and use that.
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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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/* 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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/* Non-zero for each mode that supports (set (reg) (reg)).
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This is trivially true for integer and floating point values.
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It may or may not be true for condition codes. */
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static char can_copy_p[(int) NUM_MACHINE_MODES];
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/* Non-zero if can_copy_p has been initialized. */
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static int can_copy_init_p;
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/* Element I is a list of I's predecessors/successors. */
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static int_list_ptr *s_preds;
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static int_list_ptr *s_succs;
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/* Element I is the number of predecessors/successors of basic block I. */
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static int *num_preds;
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static int *num_succs;
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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 and the operands are not modified in the basic block prior
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to 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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/* Non-zero if this [anticipatable] occurrence has been deleted. */
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char deleted_p;
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/* Non-zero 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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|
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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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*/
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/* Total size of the expression hash table, in elements. */
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static int expr_hash_table_size;
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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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static struct expr **expr_hash_table;
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||
|
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/* Total size of the copy propagation hash table, in elements. */
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static int set_hash_table_size;
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/* The table itself.
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This is an array of `set_hash_table_size' elements. */
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static struct expr **set_hash_table;
|
||
|
||
/* 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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|
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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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||
#define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)])
|
||
|
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/* Number of cuids. */
|
||
static int max_cuid;
|
||
|
||
/* Mapping of cuids to insns. */
|
||
static rtx *cuid_insn;
|
||
|
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/* Get insn from cuid. */
|
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#define CUID_INSN(CUID) (cuid_insn[CUID])
|
||
|
||
/* Maximum register number in function prior to doing gcse + 1.
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||
Registers created during this pass have regno >= max_gcse_regno.
|
||
This is named with "gcse" to not collide with global of same name. */
|
||
static int max_gcse_regno;
|
||
|
||
/* Maximum number of cse-able expressions found. */
|
||
static int n_exprs;
|
||
/* Maximum number of assignments for copy propagation found. */
|
||
static int n_sets;
|
||
|
||
/* Table of registers that are modified.
|
||
For each register, each element is a list of places where the pseudo-reg
|
||
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]. The classic GCSE
|
||
uses the information in lists.
|
||
|
||
If the classic GCSE pass is deleted `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
|
||
|
||
/* 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 sbitmap 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;
|
||
|
||
/* For each block, non-zero if memory is set in that block.
|
||
This is computed during hash table computation and is used by
|
||
expr_killed_p and compute_transp.
|
||
??? Handling of memory is very simple, we don't make any attempt
|
||
to optimize things (later).
|
||
??? This can be computed by compute_sets since the information
|
||
doesn't change. */
|
||
static char *mem_set_in_block;
|
||
|
||
/* 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;
|
||
|
||
extern char *current_function_name;
|
||
extern int current_function_calls_setjmp;
|
||
extern int current_function_calls_longjmp;
|
||
|
||
/* These variables are used by classic GCSE.
|
||
Normally they'd be defined a bit later, but `rd_gen' needs to
|
||
be declared sooner. */
|
||
|
||
/* A bitmap of all ones for implementing the algorithm for available
|
||
expressions and reaching definitions. */
|
||
/* ??? Available expression bitmaps have a different size than reaching
|
||
definition bitmaps. This should be the larger of the two, however, it
|
||
is not currently used for reaching definitions. */
|
||
static sbitmap u_bitmap;
|
||
|
||
/* 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;
|
||
|
||
static void compute_can_copy PROTO ((void));
|
||
|
||
static char *gmalloc PROTO ((unsigned int));
|
||
static char *grealloc PROTO ((char *, unsigned int));
|
||
static char *gcse_alloc PROTO ((unsigned long));
|
||
static void alloc_gcse_mem PROTO ((rtx));
|
||
static void free_gcse_mem PROTO ((void));
|
||
extern void dump_cuid_table PROTO ((FILE *));
|
||
|
||
static void alloc_reg_set_mem PROTO ((int));
|
||
static void free_reg_set_mem PROTO ((void));
|
||
static void record_one_set PROTO ((int, rtx));
|
||
static void record_set_info PROTO ((rtx, rtx));
|
||
static void compute_sets PROTO ((rtx));
|
||
|
||
static void hash_scan_insn PROTO ((rtx, int, int));
|
||
static void hash_scan_set PROTO ((rtx, rtx, int));
|
||
static void hash_scan_clobber PROTO ((rtx, rtx));
|
||
static void hash_scan_call PROTO ((rtx, rtx));
|
||
static void maybe_set_rd_gen PROTO ((int, rtx));
|
||
static int want_to_gcse_p PROTO ((rtx));
|
||
static int oprs_unchanged_p PROTO ((rtx, rtx, int));
|
||
static int oprs_anticipatable_p PROTO ((rtx, rtx));
|
||
static int oprs_available_p PROTO ((rtx, rtx));
|
||
static void insert_expr_in_table PROTO ((rtx, enum machine_mode, rtx, int, int));
|
||
static void insert_set_in_table PROTO ((rtx, rtx));
|
||
static unsigned int hash_expr PROTO ((rtx, enum machine_mode, int *, int));
|
||
static unsigned int hash_expr_1 PROTO ((rtx, enum machine_mode, int *));
|
||
static unsigned int hash_set PROTO ((int, int));
|
||
static int expr_equiv_p PROTO ((rtx, rtx));
|
||
static void record_last_reg_set_info PROTO ((rtx, int));
|
||
static void record_last_mem_set_info PROTO ((rtx));
|
||
static void record_last_set_info PROTO ((rtx, rtx));
|
||
static void compute_hash_table PROTO ((rtx, int));
|
||
static void alloc_set_hash_table PROTO ((int));
|
||
static void free_set_hash_table PROTO ((void));
|
||
static void compute_set_hash_table PROTO ((rtx));
|
||
static void alloc_expr_hash_table PROTO ((int));
|
||
static void free_expr_hash_table PROTO ((void));
|
||
static void compute_expr_hash_table PROTO ((rtx));
|
||
static void dump_hash_table PROTO ((FILE *, char *, struct expr **, int, int));
|
||
static struct expr *lookup_expr PROTO ((rtx));
|
||
static struct expr *lookup_set PROTO ((int, rtx));
|
||
static struct expr *next_set PROTO ((int, struct expr *));
|
||
static void reset_opr_set_tables PROTO ((void));
|
||
static int oprs_not_set_p PROTO ((rtx, rtx));
|
||
static void mark_call PROTO ((rtx, rtx));
|
||
static void mark_set PROTO ((rtx, rtx));
|
||
static void mark_clobber PROTO ((rtx, rtx));
|
||
static void mark_oprs_set PROTO ((rtx));
|
||
|
||
static void alloc_rd_mem PROTO ((int, int));
|
||
static void free_rd_mem PROTO ((void));
|
||
static void compute_kill_rd PROTO ((void));
|
||
static void handle_rd_kill_set PROTO ((rtx, int, int));
|
||
static void compute_rd PROTO ((void));
|
||
extern void dump_rd_table PROTO ((FILE *, char *, sbitmap *));
|
||
|
||
static void alloc_avail_expr_mem PROTO ((int, int));
|
||
static void free_avail_expr_mem PROTO ((void));
|
||
static void compute_ae_gen PROTO ((void));
|
||
static void compute_ae_kill PROTO ((void));
|
||
static int expr_killed_p PROTO ((rtx, int));
|
||
static void compute_available PROTO ((void));
|
||
|
||
static int expr_reaches_here_p PROTO ((struct occr *, struct expr *,
|
||
int, int, char *));
|
||
static rtx computing_insn PROTO ((struct expr *, rtx));
|
||
static int def_reaches_here_p PROTO ((rtx, rtx));
|
||
static int can_disregard_other_sets PROTO ((struct reg_set **, rtx, int));
|
||
static int handle_avail_expr PROTO ((rtx, struct expr *));
|
||
static int classic_gcse PROTO ((void));
|
||
static int one_classic_gcse_pass PROTO ((rtx, int));
|
||
|
||
static void alloc_cprop_mem PROTO ((int, int));
|
||
static void free_cprop_mem PROTO ((void));
|
||
extern void dump_cprop_data PROTO ((FILE *));
|
||
static void compute_transp PROTO ((rtx, int, sbitmap *, int));
|
||
static void compute_cprop_local_properties PROTO ((void));
|
||
static void compute_cprop_avinout PROTO ((void));
|
||
static void compute_cprop_data PROTO ((void));
|
||
static void find_used_regs PROTO ((rtx));
|
||
static int try_replace_reg PROTO ((rtx, rtx, rtx));
|
||
static struct expr *find_avail_set PROTO ((int, rtx));
|
||
static int cprop_insn PROTO ((rtx));
|
||
static int cprop PROTO ((void));
|
||
static int one_cprop_pass PROTO ((rtx, int));
|
||
|
||
static void alloc_pre_mem PROTO ((int, int));
|
||
static void free_pre_mem PROTO ((void));
|
||
extern void dump_pre_data PROTO ((FILE *));
|
||
static void compute_pre_local_properties PROTO ((void));
|
||
static void compute_pre_avinout PROTO ((void));
|
||
static void compute_pre_antinout PROTO ((void));
|
||
static void compute_pre_pavinout PROTO ((void));
|
||
static void compute_pre_ppinout PROTO ((void));
|
||
static void compute_pre_data PROTO ((void));
|
||
static int pre_expr_reaches_here_p PROTO ((struct occr *, struct expr *,
|
||
int, char *));
|
||
static void pre_insert_insn PROTO ((struct expr *, int));
|
||
static void pre_insert PROTO ((struct expr **));
|
||
static void pre_insert_copy_insn PROTO ((struct expr *, rtx));
|
||
static void pre_insert_copies PROTO ((void));
|
||
static int pre_delete PROTO ((void));
|
||
static int pre_gcse PROTO ((void));
|
||
static int one_pre_gcse_pass PROTO ((rtx, int));
|
||
|
||
static void add_label_notes PROTO ((rtx, rtx));
|
||
|
||
/* Entry point for global common subexpression elimination.
|
||
F is the first instruction in the function. */
|
||
|
||
void
|
||
gcse_main (f, file)
|
||
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;
|
||
|
||
/* It's impossible to construct a correct control flow graph in the
|
||
presense of setjmp, so just punt to be safe. */
|
||
if (current_function_calls_setjmp)
|
||
return;
|
||
|
||
/* For calling dump_foo fns from gdb. */
|
||
debug_stderr = stderr;
|
||
|
||
max_gcse_regno = max_reg_num ();
|
||
find_basic_blocks (f, max_gcse_regno, file, 0);
|
||
|
||
/* Return if there's nothing to do. */
|
||
if (n_basic_blocks <= 1)
|
||
{
|
||
/* Free storage allocated by find_basic_blocks. */
|
||
free_basic_block_vars (0);
|
||
return;
|
||
}
|
||
|
||
/* See what modes support reg/reg copy operations. */
|
||
if (! can_copy_init_p)
|
||
{
|
||
compute_can_copy ();
|
||
can_copy_init_p = 1;
|
||
}
|
||
|
||
gcc_obstack_init (&gcse_obstack);
|
||
|
||
gcse_file = file;
|
||
|
||
/* Allocate and compute predecessors/successors. */
|
||
|
||
s_preds = (int_list_ptr *) alloca (n_basic_blocks * sizeof (int_list_ptr));
|
||
s_succs = (int_list_ptr *) alloca (n_basic_blocks * sizeof (int_list_ptr));
|
||
num_preds = (int *) alloca (n_basic_blocks * sizeof (int));
|
||
num_succs = (int *) alloca (n_basic_blocks * sizeof (int));
|
||
bytes_used = 4 * n_basic_blocks * sizeof (int_list_ptr);
|
||
compute_preds_succs (s_preds, s_succs, num_preds, num_succs);
|
||
|
||
if (file)
|
||
{
|
||
dump_bb_data (file, s_preds, s_succs);
|
||
}
|
||
|
||
/* Record where pseudo-registers are set.
|
||
This data is kept accurate during each pass.
|
||
??? We could also record hard-reg and memory information here
|
||
[since it's unchanging], however it is currently done during
|
||
hash table computation. */
|
||
|
||
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_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);
|
||
|
||
changed = one_cprop_pass (f, pass + 1);
|
||
|
||
if (optimize_size)
|
||
changed |= one_classic_gcse_pass (f, pass + 1);
|
||
else
|
||
changed |= one_pre_gcse_pass (f, pass + 1);
|
||
|
||
if (max_pass_bytes < bytes_used)
|
||
max_pass_bytes = bytes_used;
|
||
|
||
free_gcse_mem ();
|
||
|
||
if (file)
|
||
{
|
||
fprintf (file, "\n");
|
||
fflush (file);
|
||
}
|
||
obstack_free (&gcse_obstack, gcse_obstack_bottom);
|
||
pass++;
|
||
}
|
||
|
||
/* If we're doing PRE, do one last pass of copy propagation. */
|
||
if (! optimize_size)
|
||
{
|
||
max_gcse_regno = max_reg_num ();
|
||
alloc_gcse_mem (f);
|
||
one_cprop_pass (f, pass + 1);
|
||
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);
|
||
}
|
||
|
||
/* Free our obstack. */
|
||
obstack_free (&gcse_obstack, NULL_PTR);
|
||
/* Free reg_set_table. */
|
||
free_reg_set_mem ();
|
||
/* Free storage used to record predecessor/successor data. */
|
||
free_bb_mem ();
|
||
/* Free storage allocated by find_basic_blocks. */
|
||
free_basic_block_vars (0);
|
||
}
|
||
|
||
/* Misc. utilities. */
|
||
|
||
/* Compute which modes support reg/reg copy operations. */
|
||
|
||
static void
|
||
compute_can_copy ()
|
||
{
|
||
int i;
|
||
#ifndef AVOID_CCMODE_COPIES
|
||
rtx reg,insn;
|
||
#endif
|
||
char *free_point = (char *) oballoc (1);
|
||
|
||
bzero (can_copy_p, NUM_MACHINE_MODES);
|
||
|
||
start_sequence ();
|
||
for (i = 0; i < NUM_MACHINE_MODES; i++)
|
||
{
|
||
switch (GET_MODE_CLASS (i))
|
||
{
|
||
case MODE_CC :
|
||
#ifdef AVOID_CCMODE_COPIES
|
||
can_copy_p[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_PTR) >= 0)
|
||
can_copy_p[i] = 1;
|
||
#endif
|
||
break;
|
||
default :
|
||
can_copy_p[i] = 1;
|
||
break;
|
||
}
|
||
}
|
||
end_sequence ();
|
||
|
||
/* Free the objects we just allocated. */
|
||
obfree (free_point);
|
||
}
|
||
|
||
/* Cover function to xmalloc to record bytes allocated. */
|
||
|
||
static char *
|
||
gmalloc (size)
|
||
unsigned int size;
|
||
{
|
||
bytes_used += size;
|
||
return xmalloc (size);
|
||
}
|
||
|
||
/* 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 char *
|
||
grealloc (ptr, size)
|
||
char *ptr;
|
||
unsigned int size;
|
||
{
|
||
return xrealloc (ptr, size);
|
||
}
|
||
|
||
/* Cover function to obstack_alloc.
|
||
We don't need to record the bytes allocated here since
|
||
obstack_chunk_alloc is set to gmalloc. */
|
||
|
||
static char *
|
||
gcse_alloc (size)
|
||
unsigned long size;
|
||
{
|
||
return (char *) 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 (f)
|
||
rtx f;
|
||
{
|
||
int i,n;
|
||
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 ();
|
||
n = (max_uid + 1) * sizeof (int);
|
||
uid_cuid = (int *) gmalloc (n);
|
||
bzero ((char *) uid_cuid, n);
|
||
for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
|
||
{
|
||
if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
|
||
INSN_CUID (insn) = i++;
|
||
else
|
||
INSN_CUID (insn) = i;
|
||
}
|
||
|
||
/* Create a table mapping cuids to insns. */
|
||
|
||
max_cuid = i;
|
||
n = (max_cuid + 1) * sizeof (rtx);
|
||
cuid_insn = (rtx *) gmalloc (n);
|
||
bzero ((char *) cuid_insn, n);
|
||
for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
|
||
{
|
||
if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
|
||
{
|
||
CUID_INSN (i) = insn;
|
||
i++;
|
||
}
|
||
}
|
||
|
||
/* Allocate vars to track sets of regs. */
|
||
|
||
reg_set_bitmap = (sbitmap) sbitmap_alloc (max_gcse_regno);
|
||
|
||
/* Allocate vars to track sets of regs, memory per block. */
|
||
|
||
reg_set_in_block = (sbitmap *) sbitmap_vector_alloc (n_basic_blocks,
|
||
max_gcse_regno);
|
||
mem_set_in_block = (char *) gmalloc (n_basic_blocks);
|
||
}
|
||
|
||
/* Free memory allocated by alloc_gcse_mem. */
|
||
|
||
static void
|
||
free_gcse_mem ()
|
||
{
|
||
free (uid_cuid);
|
||
free (cuid_insn);
|
||
|
||
free (reg_set_bitmap);
|
||
|
||
free (reg_set_in_block);
|
||
free (mem_set_in_block);
|
||
}
|
||
|
||
void
|
||
dump_cuid_table (file)
|
||
FILE *file;
|
||
{
|
||
int i,n;
|
||
|
||
fprintf (file, "CUID table\n");
|
||
for (i = n = 0; i < max_cuid; i++)
|
||
{
|
||
rtx insn = CUID_INSN (i);
|
||
if (n != 0 && n % 10 == 0)
|
||
fprintf (file, "\n");
|
||
if (insn != NULL)
|
||
fprintf (file, " %d", INSN_UID (insn));
|
||
}
|
||
fprintf (file, "\n\n");
|
||
}
|
||
|
||
/* 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 (n_regs)
|
||
int n_regs;
|
||
{
|
||
int n;
|
||
|
||
reg_set_table_size = n_regs + REG_SET_TABLE_SLOP;
|
||
n = reg_set_table_size * sizeof (struct reg_set *);
|
||
reg_set_table = (struct reg_set **) gmalloc (n);
|
||
bzero ((char *) reg_set_table, n);
|
||
|
||
gcc_obstack_init (®_set_obstack);
|
||
}
|
||
|
||
static void
|
||
free_reg_set_mem ()
|
||
{
|
||
free (reg_set_table);
|
||
obstack_free (®_set_obstack, NULL_PTR);
|
||
}
|
||
|
||
/* Record REGNO in the reg_set table. */
|
||
|
||
static void
|
||
record_one_set (regno, insn)
|
||
int regno;
|
||
rtx insn;
|
||
{
|
||
/* allocate a new reg_set element and link it onto the list */
|
||
struct reg_set *new_reg_info, *reg_info_ptr1, *reg_info_ptr2;
|
||
|
||
/* 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 = (struct reg_set **)
|
||
grealloc ((char *) reg_set_table,
|
||
new_size * sizeof (struct reg_set *));
|
||
bzero ((char *) (reg_set_table + reg_set_table_size),
|
||
(new_size - reg_set_table_size) * sizeof (struct reg_set *));
|
||
reg_set_table_size = new_size;
|
||
}
|
||
|
||
new_reg_info = (struct reg_set *) obstack_alloc (®_set_obstack,
|
||
sizeof (struct reg_set));
|
||
bytes_used += sizeof (struct reg_set);
|
||
new_reg_info->insn = insn;
|
||
new_reg_info->next = NULL;
|
||
if (reg_set_table[regno] == NULL)
|
||
reg_set_table[regno] = new_reg_info;
|
||
else
|
||
{
|
||
reg_info_ptr1 = reg_info_ptr2 = reg_set_table[regno];
|
||
/* ??? One could keep a "last" pointer to speed this up. */
|
||
while (reg_info_ptr1 != NULL)
|
||
{
|
||
reg_info_ptr2 = reg_info_ptr1;
|
||
reg_info_ptr1 = reg_info_ptr1->next;
|
||
}
|
||
reg_info_ptr2->next = new_reg_info;
|
||
}
|
||
}
|
||
|
||
/* For communication between next two functions (via note_stores). */
|
||
static rtx record_set_insn;
|
||
|
||
/* Called from compute_sets via note_stores to handle one
|
||
SET or CLOBBER in an insn. */
|
||
|
||
static void
|
||
record_set_info (dest, setter)
|
||
rtx dest, setter ATTRIBUTE_UNUSED;
|
||
{
|
||
if (GET_CODE (dest) == SUBREG)
|
||
dest = SUBREG_REG (dest);
|
||
|
||
if (GET_CODE (dest) == REG)
|
||
{
|
||
if (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 docs. */
|
||
|
||
static void
|
||
compute_sets (f)
|
||
rtx f;
|
||
{
|
||
rtx insn = f;
|
||
|
||
while (insn)
|
||
{
|
||
if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
|
||
{
|
||
record_set_insn = insn;
|
||
note_stores (PATTERN (insn), record_set_info);
|
||
}
|
||
insn = NEXT_INSN (insn);
|
||
}
|
||
}
|
||
|
||
/* Hash table support. */
|
||
|
||
#define NEVER_SET -1
|
||
|
||
/* For each register, the cuid of the first/last insn in the block to set it,
|
||
or zero if not set. */
|
||
static int *reg_first_set;
|
||
static int *reg_last_set;
|
||
|
||
/* While computing "first/last set" info, this is the CUID of first/last insn
|
||
to set memory or zero if not set. `mem_last_set' is also used when
|
||
performing GCSE to record whether memory has been set since the beginning
|
||
of the block.
|
||
Note that handling of memory is very simple, we don't make any attempt
|
||
to optimize things (later). */
|
||
static int mem_first_set;
|
||
static int mem_last_set;
|
||
|
||
/* Set the appropriate bit in `rd_gen' [the gen for reaching defs] if the
|
||
register set in this insn is not set after this insn in this block. */
|
||
|
||
static void
|
||
maybe_set_rd_gen (regno, insn)
|
||
int regno;
|
||
rtx insn;
|
||
{
|
||
if (reg_last_set[regno] <= INSN_CUID (insn))
|
||
SET_BIT (rd_gen[BLOCK_NUM (insn)], INSN_CUID (insn));
|
||
}
|
||
|
||
/* Perform a quick check whether X, the source of a set, is something
|
||
we want to consider for GCSE. */
|
||
|
||
static int
|
||
want_to_gcse_p (x)
|
||
rtx x;
|
||
{
|
||
enum rtx_code code = GET_CODE (x);
|
||
|
||
switch (code)
|
||
{
|
||
case REG:
|
||
case SUBREG:
|
||
case CONST_INT:
|
||
case CONST_DOUBLE:
|
||
case CALL:
|
||
return 0;
|
||
|
||
default:
|
||
break;
|
||
}
|
||
|
||
return 1;
|
||
}
|
||
|
||
/* Return non-zero 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 (x, insn, avail_p)
|
||
rtx x, insn;
|
||
int avail_p;
|
||
{
|
||
int i;
|
||
enum rtx_code code;
|
||
char *fmt;
|
||
|
||
/* repeat is used to turn tail-recursion into iteration. */
|
||
repeat:
|
||
|
||
if (x == 0)
|
||
return 1;
|
||
|
||
code = GET_CODE (x);
|
||
switch (code)
|
||
{
|
||
case REG:
|
||
if (avail_p)
|
||
return (reg_last_set[REGNO (x)] == NEVER_SET
|
||
|| reg_last_set[REGNO (x)] < INSN_CUID (insn));
|
||
else
|
||
return (reg_first_set[REGNO (x)] == NEVER_SET
|
||
|| reg_first_set[REGNO (x)] >= INSN_CUID (insn));
|
||
|
||
case MEM:
|
||
if (avail_p)
|
||
{
|
||
if (mem_last_set != NEVER_SET
|
||
&& mem_last_set >= INSN_CUID (insn))
|
||
return 0;
|
||
}
|
||
else
|
||
{
|
||
if (mem_first_set != NEVER_SET
|
||
&& mem_first_set < INSN_CUID (insn))
|
||
return 0;
|
||
}
|
||
x = XEXP (x, 0);
|
||
goto repeat;
|
||
|
||
case PRE_DEC:
|
||
case PRE_INC:
|
||
case POST_DEC:
|
||
case POST_INC:
|
||
return 0;
|
||
|
||
case PC:
|
||
case CC0: /*FIXME*/
|
||
case CONST:
|
||
case CONST_INT:
|
||
case CONST_DOUBLE:
|
||
case SYMBOL_REF:
|
||
case LABEL_REF:
|
||
case ADDR_VEC:
|
||
case ADDR_DIFF_VEC:
|
||
return 1;
|
||
|
||
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.
|
||
This function is called enough to be worth it. */
|
||
if (i == 0)
|
||
{
|
||
x = tem;
|
||
goto repeat;
|
||
}
|
||
if (! oprs_unchanged_p (tem, insn, avail_p))
|
||
return 0;
|
||
}
|
||
else if (fmt[i] == 'E')
|
||
{
|
||
int j;
|
||
for (j = 0; j < XVECLEN (x, i); j++)
|
||
{
|
||
if (! oprs_unchanged_p (XVECEXP (x, i, j), insn, avail_p))
|
||
return 0;
|
||
}
|
||
}
|
||
}
|
||
|
||
return 1;
|
||
}
|
||
|
||
/* Return non-zero 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 (x, insn)
|
||
rtx x, insn;
|
||
{
|
||
return oprs_unchanged_p (x, insn, 0);
|
||
}
|
||
|
||
/* Return non-zero if the operands of expression X are unchanged from
|
||
INSN to the end of INSN's basic block. */
|
||
|
||
static int
|
||
oprs_available_p (x, insn)
|
||
rtx x, insn;
|
||
{
|
||
return oprs_unchanged_p (x, insn, 1);
|
||
}
|
||
|
||
/* Hash expression X.
|
||
MODE is only used if X is a CONST_INT.
|
||
A boolean indicating if a volatile operand is found or if the expression
|
||
contains something we don't want to insert in the table is stored in
|
||
DO_NOT_RECORD_P.
|
||
|
||
??? One might want to merge this with canon_hash. Later. */
|
||
|
||
static unsigned int
|
||
hash_expr (x, mode, do_not_record_p, hash_table_size)
|
||
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;
|
||
}
|
||
|
||
/* Subroutine of hash_expr to do the actual work. */
|
||
|
||
static unsigned int
|
||
hash_expr_1 (x, mode, do_not_record_p)
|
||
rtx x;
|
||
enum machine_mode mode;
|
||
int *do_not_record_p;
|
||
{
|
||
int i, j;
|
||
unsigned hash = 0;
|
||
enum rtx_code code;
|
||
char *fmt;
|
||
|
||
/* repeat is used to turn tail-recursion into iteration. */
|
||
repeat:
|
||
|
||
if (x == 0)
|
||
return hash;
|
||
|
||
code = GET_CODE (x);
|
||
switch (code)
|
||
{
|
||
case REG:
|
||
{
|
||
register int regno = REGNO (x);
|
||
hash += ((unsigned) REG << 7) + regno;
|
||
return hash;
|
||
}
|
||
|
||
case CONST_INT:
|
||
{
|
||
unsigned HOST_WIDE_INT tem = INTVAL (x);
|
||
hash += ((unsigned) CONST_INT << 7) + (unsigned) mode + tem;
|
||
return hash;
|
||
}
|
||
|
||
case CONST_DOUBLE:
|
||
/* This is like the general case, except that it only counts
|
||
the integers representing the constant. */
|
||
hash += (unsigned) code + (unsigned) GET_MODE (x);
|
||
if (GET_MODE (x) != VOIDmode)
|
||
for (i = 2; i < GET_RTX_LENGTH (CONST_DOUBLE); i++)
|
||
{
|
||
unsigned tem = XINT (x, i);
|
||
hash += tem;
|
||
}
|
||
else
|
||
hash += ((unsigned) CONST_DOUBLE_LOW (x)
|
||
+ (unsigned) CONST_DOUBLE_HIGH (x));
|
||
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) 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;
|
||
unsigned char *p = (unsigned char *) XSTR (x, 0);
|
||
while (*p)
|
||
h += (h << 7) + *p++; /* ??? revisit */
|
||
hash += ((unsigned) SYMBOL_REF << 7) + h;
|
||
return hash;
|
||
}
|
||
|
||
case MEM:
|
||
if (MEM_VOLATILE_P (x))
|
||
{
|
||
*do_not_record_p = 1;
|
||
return 0;
|
||
}
|
||
hash += (unsigned) MEM;
|
||
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;
|
||
}
|
||
|
||
default:
|
||
break;
|
||
}
|
||
|
||
i = GET_RTX_LENGTH (code) - 1;
|
||
hash += (unsigned) code + (unsigned) GET_MODE (x);
|
||
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.
|
||
This function is called enough to be worth it. */
|
||
if (i == 0)
|
||
{
|
||
x = tem;
|
||
goto repeat;
|
||
}
|
||
hash += hash_expr_1 (tem, 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')
|
||
{
|
||
register unsigned char *p = (unsigned char *) XSTR (x, i);
|
||
if (p)
|
||
while (*p)
|
||
hash += *p++;
|
||
}
|
||
else if (fmt[i] == 'i')
|
||
{
|
||
register unsigned tem = XINT (x, i);
|
||
hash += tem;
|
||
}
|
||
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 (regno, hash_table_size)
|
||
int regno;
|
||
int hash_table_size;
|
||
{
|
||
unsigned int hash;
|
||
|
||
hash = regno;
|
||
return hash % hash_table_size;
|
||
}
|
||
|
||
/* Return non-zero if exp1 is equivalent to exp2.
|
||
??? Borrowed from cse.c. Might want to remerge with cse.c. Later. */
|
||
|
||
static int
|
||
expr_equiv_p (x, y)
|
||
rtx x, y;
|
||
{
|
||
register int i, j;
|
||
register enum rtx_code code;
|
||
register char *fmt;
|
||
|
||
if (x == y)
|
||
return 1;
|
||
if (x == 0 || y == 0)
|
||
return x == y;
|
||
|
||
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:
|
||
return x == y;
|
||
|
||
case CONST_INT:
|
||
return INTVAL (x) == INTVAL (y);
|
||
|
||
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);
|
||
|
||
/* 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))));
|
||
|
||
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 non-zero if X is an anticipatable expression.
|
||
AVAIL_P is non-zero if X is an available expression. */
|
||
|
||
static void
|
||
insert_expr_in_table (x, mode, insn, antic_p, avail_p)
|
||
rtx x;
|
||
enum machine_mode mode;
|
||
rtx insn;
|
||
int antic_p, avail_p;
|
||
{
|
||
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, expr_hash_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 = expr_hash_table[hash];
|
||
found = 0;
|
||
|
||
while (cur_expr && ! (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 = (struct expr *) gcse_alloc (sizeof (struct expr));
|
||
bytes_used += sizeof (struct expr);
|
||
if (expr_hash_table[hash] == NULL)
|
||
{
|
||
/* This is the first pattern that hashed to this index. */
|
||
expr_hash_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 = n_exprs++;
|
||
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 = (struct 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 = (struct 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 (x, insn)
|
||
rtx x;
|
||
rtx insn;
|
||
{
|
||
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)), set_hash_table_size);
|
||
|
||
cur_expr = set_hash_table[hash];
|
||
found = 0;
|
||
|
||
while (cur_expr && ! (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 = (struct expr *) gcse_alloc (sizeof (struct expr));
|
||
bytes_used += sizeof (struct expr);
|
||
if (set_hash_table[hash] == NULL)
|
||
{
|
||
/* This is the first pattern that hashed to this index. */
|
||
set_hash_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. */
|
||
/* ??? Should this go in a different obstack? */
|
||
cur_expr->expr = copy_rtx (x);
|
||
cur_expr->bitmap_index = n_sets++;
|
||
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 = (struct 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;
|
||
}
|
||
}
|
||
|
||
/* Scan pattern PAT of INSN and add an entry to the hash table.
|
||
If SET_P is non-zero, this is for the assignment hash table,
|
||
otherwise it is for the expression hash table. */
|
||
|
||
static void
|
||
hash_scan_set (pat, insn, set_p)
|
||
rtx pat, insn;
|
||
int set_p;
|
||
{
|
||
rtx src = SET_SRC (pat);
|
||
rtx dest = SET_DEST (pat);
|
||
|
||
if (GET_CODE (src) == CALL)
|
||
hash_scan_call (src, insn);
|
||
|
||
if (GET_CODE (dest) == REG)
|
||
{
|
||
int regno = REGNO (dest);
|
||
rtx tmp;
|
||
|
||
/* Only record sets of pseudo-regs in the hash table. */
|
||
if (! 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)]
|
||
/* Is SET_SRC something we want to gcse? */
|
||
&& want_to_gcse_p (src))
|
||
{
|
||
/* An expression is not anticipatable if its operands are
|
||
modified before this insn. */
|
||
int antic_p = ! optimize_size && oprs_anticipatable_p (src, insn);
|
||
/* An expression is not available if its operands are
|
||
subsequently modified, including this insn. */
|
||
int avail_p = oprs_available_p (src, insn);
|
||
insert_expr_in_table (src, GET_MODE (dest), insn, antic_p, avail_p);
|
||
}
|
||
/* Record sets for constant/copy propagation. */
|
||
else if (set_p
|
||
&& regno >= FIRST_PSEUDO_REGISTER
|
||
&& ((GET_CODE (src) == REG
|
||
&& REGNO (src) >= FIRST_PSEUDO_REGISTER
|
||
&& can_copy_p [GET_MODE (dest)])
|
||
/* ??? CONST_INT:wip */
|
||
|| GET_CODE (src) == CONST_INT)
|
||
/* 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 == BLOCK_END (BLOCK_NUM (insn))
|
||
|| ((tmp = next_nonnote_insn (insn)) != NULL_RTX
|
||
&& oprs_available_p (pat, tmp))))
|
||
insert_set_in_table (pat, insn);
|
||
}
|
||
|
||
/* Check if first/last set in this block for classic gcse,
|
||
but not for copy/constant propagation. */
|
||
if (optimize_size && !set_p)
|
||
|
||
{
|
||
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)
|
||
maybe_set_rd_gen (REGNO (dest), insn);
|
||
}
|
||
}
|
||
|
||
static void
|
||
hash_scan_clobber (x, insn)
|
||
rtx x ATTRIBUTE_UNUSED, insn ATTRIBUTE_UNUSED;
|
||
{
|
||
/* Currently nothing to do. */
|
||
}
|
||
|
||
static void
|
||
hash_scan_call (x, insn)
|
||
rtx x ATTRIBUTE_UNUSED, insn 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 non-zero, 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 (insn, set_p, in_libcall_block)
|
||
rtx insn;
|
||
int set_p;
|
||
int in_libcall_block;
|
||
{
|
||
rtx pat = PATTERN (insn);
|
||
|
||
/* Pick out the sets of INSN and for other forms of instructions record
|
||
what's been modified. */
|
||
|
||
if (GET_CODE (pat) == SET && ! in_libcall_block)
|
||
hash_scan_set (pat, insn, set_p);
|
||
else if (GET_CODE (pat) == PARALLEL)
|
||
{
|
||
int i;
|
||
|
||
for (i = 0; i < XVECLEN (pat, 0); i++)
|
||
{
|
||
rtx x = XVECEXP (pat, 0, i);
|
||
|
||
if (GET_CODE (x) == SET)
|
||
{
|
||
if (GET_CODE (SET_SRC (x)) == CALL)
|
||
hash_scan_call (SET_SRC (x), insn);
|
||
|
||
/* Check if first/last set in this block for classic
|
||
gcse, but not for constant/copy propagation. */
|
||
if (optimize_size && !set_p)
|
||
{
|
||
rtx dest = SET_DEST (x);
|
||
|
||
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)
|
||
maybe_set_rd_gen (REGNO (dest), insn);
|
||
}
|
||
}
|
||
else if (GET_CODE (x) == CLOBBER)
|
||
hash_scan_clobber (x, insn);
|
||
else if (GET_CODE (x) == CALL)
|
||
hash_scan_call (x, insn);
|
||
}
|
||
}
|
||
else if (GET_CODE (pat) == CLOBBER)
|
||
hash_scan_clobber (pat, insn);
|
||
else if (GET_CODE (pat) == CALL)
|
||
hash_scan_call (pat, insn);
|
||
}
|
||
|
||
static void
|
||
dump_hash_table (file, name, table, table_size, total_size)
|
||
FILE *file;
|
||
char *name;
|
||
struct expr **table;
|
||
int table_size, total_size;
|
||
{
|
||
int i;
|
||
/* Flattened out table, so it's printed in proper order. */
|
||
struct expr **flat_table = (struct expr **) alloca (total_size * sizeof (struct expr *));
|
||
unsigned int *hash_val = (unsigned int *) alloca (total_size * sizeof (unsigned int));
|
||
|
||
bzero ((char *) flat_table, total_size * sizeof (struct expr *));
|
||
for (i = 0; i < table_size; i++)
|
||
{
|
||
struct expr *expr;
|
||
|
||
for (expr = 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, total_size);
|
||
|
||
for (i = 0; i < total_size; i++)
|
||
{
|
||
struct expr *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");
|
||
}
|
||
|
||
/* Record register first/last/block set information for REGNO in INSN.
|
||
reg_first_set records the first place in the block where the register
|
||
is set and is used to compute "anticipatability".
|
||
reg_last_set records the last place in the block where the register
|
||
is set and is used to compute "availability".
|
||
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 (insn, regno)
|
||
rtx insn;
|
||
int regno;
|
||
{
|
||
if (reg_first_set[regno] == NEVER_SET)
|
||
reg_first_set[regno] = INSN_CUID (insn);
|
||
reg_last_set[regno] = INSN_CUID (insn);
|
||
SET_BIT (reg_set_in_block[BLOCK_NUM (insn)], regno);
|
||
}
|
||
|
||
/* Record memory first/last/block set information for INSN. */
|
||
|
||
static void
|
||
record_last_mem_set_info (insn)
|
||
rtx insn;
|
||
{
|
||
if (mem_first_set == NEVER_SET)
|
||
mem_first_set = INSN_CUID (insn);
|
||
mem_last_set = INSN_CUID (insn);
|
||
mem_set_in_block[BLOCK_NUM (insn)] = 1;
|
||
}
|
||
|
||
/* Used for communicating between next two routines. */
|
||
static rtx last_set_insn;
|
||
|
||
/* Called from compute_hash_table via note_stores to handle one
|
||
SET or CLOBBER in an insn. */
|
||
|
||
static void
|
||
record_last_set_info (dest, setter)
|
||
rtx dest, setter ATTRIBUTE_UNUSED;
|
||
{
|
||
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.
|
||
|
||
F is the first insn.
|
||
SET_P is non-zero for computing the assignment hash table. */
|
||
|
||
static void
|
||
compute_hash_table (f, set_p)
|
||
rtx f ATTRIBUTE_UNUSED;
|
||
int set_p;
|
||
{
|
||
int bb;
|
||
|
||
/* While we compute the hash table we also compute a bit array of which
|
||
registers are set in which blocks.
|
||
We also compute which blocks set memory, in the absence of aliasing
|
||
support [which is TODO].
|
||
??? This isn't needed during const/copy propagation, but it's cheap to
|
||
compute. Later. */
|
||
sbitmap_vector_zero (reg_set_in_block, n_basic_blocks);
|
||
bzero ((char *) mem_set_in_block, n_basic_blocks);
|
||
|
||
/* Some working arrays used to track first and last set in each block. */
|
||
/* ??? One could use alloca here, but at some size a threshold is crossed
|
||
beyond which one should use malloc. Are we at that threshold here? */
|
||
reg_first_set = (int *) gmalloc (max_gcse_regno * sizeof (int));
|
||
reg_last_set = (int *) gmalloc (max_gcse_regno * sizeof (int));
|
||
|
||
for (bb = 0; bb < n_basic_blocks; bb++)
|
||
{
|
||
rtx insn;
|
||
int regno;
|
||
int in_libcall_block;
|
||
int i;
|
||
|
||
/* First pass over the instructions records information used to
|
||
determine when registers and memory are first and last set.
|
||
??? The mem_set_in_block and hard-reg reg_set_in_block computation
|
||
could be moved to compute_sets since they currently don't change. */
|
||
|
||
for (i = 0; i < max_gcse_regno; i++)
|
||
reg_first_set[i] = reg_last_set[i] = NEVER_SET;
|
||
mem_first_set = NEVER_SET;
|
||
mem_last_set = NEVER_SET;
|
||
|
||
for (insn = basic_block_head[bb];
|
||
insn && insn != NEXT_INSN (basic_block_end[bb]);
|
||
insn = NEXT_INSN (insn))
|
||
{
|
||
#ifdef NON_SAVING_SETJMP
|
||
if (NON_SAVING_SETJMP && GET_CODE (insn) == NOTE
|
||
&& NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP)
|
||
{
|
||
for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
|
||
record_last_reg_set_info (insn, regno);
|
||
continue;
|
||
}
|
||
#endif
|
||
|
||
if (GET_RTX_CLASS (GET_CODE (insn)) != 'i')
|
||
continue;
|
||
|
||
if (GET_CODE (insn) == CALL_INSN)
|
||
{
|
||
for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
|
||
if (call_used_regs[regno])
|
||
record_last_reg_set_info (insn, regno);
|
||
if (! CONST_CALL_P (insn))
|
||
record_last_mem_set_info (insn);
|
||
}
|
||
|
||
last_set_insn = insn;
|
||
note_stores (PATTERN (insn), record_last_set_info);
|
||
}
|
||
|
||
/* The next pass builds the hash table. */
|
||
|
||
for (insn = basic_block_head[bb], in_libcall_block = 0;
|
||
insn && insn != NEXT_INSN (basic_block_end[bb]);
|
||
insn = NEXT_INSN (insn))
|
||
{
|
||
if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
|
||
{
|
||
if (find_reg_note (insn, REG_LIBCALL, NULL_RTX))
|
||
in_libcall_block = 1;
|
||
else if (find_reg_note (insn, REG_RETVAL, NULL_RTX))
|
||
in_libcall_block = 0;
|
||
hash_scan_insn (insn, set_p, in_libcall_block);
|
||
}
|
||
}
|
||
}
|
||
|
||
free (reg_first_set);
|
||
free (reg_last_set);
|
||
/* Catch bugs early. */
|
||
reg_first_set = reg_last_set = 0;
|
||
}
|
||
|
||
/* Allocate space for the set hash table.
|
||
N_INSNS is the number of instructions in the function.
|
||
It is used to determine the number of buckets to use. */
|
||
|
||
static void
|
||
alloc_set_hash_table (n_insns)
|
||
int n_insns;
|
||
{
|
||
int n;
|
||
|
||
set_hash_table_size = n_insns / 4;
|
||
if (set_hash_table_size < 11)
|
||
set_hash_table_size = 11;
|
||
/* Attempt to maintain efficient use of hash table.
|
||
Making it an odd number is simplest for now.
|
||
??? Later take some measurements. */
|
||
set_hash_table_size |= 1;
|
||
n = set_hash_table_size * sizeof (struct expr *);
|
||
set_hash_table = (struct expr **) gmalloc (n);
|
||
}
|
||
|
||
/* Free things allocated by alloc_set_hash_table. */
|
||
|
||
static void
|
||
free_set_hash_table ()
|
||
{
|
||
free (set_hash_table);
|
||
}
|
||
|
||
/* Compute the hash table for doing copy/const propagation. */
|
||
|
||
static void
|
||
compute_set_hash_table (f)
|
||
rtx f;
|
||
{
|
||
/* Initialize count of number of entries in hash table. */
|
||
n_sets = 0;
|
||
bzero ((char *) set_hash_table, set_hash_table_size * sizeof (struct expr *));
|
||
|
||
compute_hash_table (f, 1);
|
||
}
|
||
|
||
/* Allocate space for the expression hash table.
|
||
N_INSNS is the number of instructions in the function.
|
||
It is used to determine the number of buckets to use. */
|
||
|
||
static void
|
||
alloc_expr_hash_table (n_insns)
|
||
int n_insns;
|
||
{
|
||
int n;
|
||
|
||
expr_hash_table_size = n_insns / 2;
|
||
/* Make sure the amount is usable. */
|
||
if (expr_hash_table_size < 11)
|
||
expr_hash_table_size = 11;
|
||
/* Attempt to maintain efficient use of hash table.
|
||
Making it an odd number is simplest for now.
|
||
??? Later take some measurements. */
|
||
expr_hash_table_size |= 1;
|
||
n = expr_hash_table_size * sizeof (struct expr *);
|
||
expr_hash_table = (struct expr **) gmalloc (n);
|
||
}
|
||
|
||
/* Free things allocated by alloc_expr_hash_table. */
|
||
|
||
static void
|
||
free_expr_hash_table ()
|
||
{
|
||
free (expr_hash_table);
|
||
}
|
||
|
||
/* Compute the hash table for doing GCSE. */
|
||
|
||
static void
|
||
compute_expr_hash_table (f)
|
||
rtx f;
|
||
{
|
||
/* Initialize count of number of entries in hash table. */
|
||
n_exprs = 0;
|
||
bzero ((char *) expr_hash_table, expr_hash_table_size * sizeof (struct expr *));
|
||
|
||
compute_hash_table (f, 0);
|
||
}
|
||
|
||
/* 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 (pat)
|
||
rtx pat;
|
||
{
|
||
int do_not_record_p;
|
||
unsigned int hash = hash_expr (pat, GET_MODE (pat), &do_not_record_p,
|
||
expr_hash_table_size);
|
||
struct expr *expr;
|
||
|
||
if (do_not_record_p)
|
||
return NULL;
|
||
|
||
expr = expr_hash_table[hash];
|
||
|
||
while (expr && ! expr_equiv_p (expr->expr, pat))
|
||
expr = expr->next_same_hash;
|
||
|
||
return expr;
|
||
}
|
||
|
||
/* Lookup REGNO in the set table.
|
||
If PAT is non-NULL look for the entry that matches it, otherwise return
|
||
the first entry for REGNO.
|
||
The result is a pointer to the table entry, or NULL if not found. */
|
||
|
||
static struct expr *
|
||
lookup_set (regno, pat)
|
||
int regno;
|
||
rtx pat;
|
||
{
|
||
unsigned int hash = hash_set (regno, set_hash_table_size);
|
||
struct expr *expr;
|
||
|
||
expr = set_hash_table[hash];
|
||
|
||
if (pat)
|
||
{
|
||
while (expr && ! expr_equiv_p (expr->expr, pat))
|
||
expr = expr->next_same_hash;
|
||
}
|
||
else
|
||
{
|
||
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 (regno, expr)
|
||
int regno;
|
||
struct expr *expr;
|
||
{
|
||
do
|
||
expr = expr->next_same_hash;
|
||
while (expr && REGNO (SET_DEST (expr->expr)) != regno);
|
||
return expr;
|
||
}
|
||
|
||
/* Reset tables used to keep track of what's still available [since the
|
||
start of the block]. */
|
||
|
||
static void
|
||
reset_opr_set_tables ()
|
||
{
|
||
/* Maintain a bitmap of which regs have been set since beginning of
|
||
the block. */
|
||
sbitmap_zero (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. */
|
||
mem_last_set = 0;
|
||
}
|
||
|
||
/* Return non-zero if the operands of X are not set before INSN in
|
||
INSN's basic block. */
|
||
|
||
static int
|
||
oprs_not_set_p (x, insn)
|
||
rtx x, insn;
|
||
{
|
||
int i;
|
||
enum rtx_code code;
|
||
char *fmt;
|
||
|
||
/* repeat is used to turn tail-recursion into iteration. */
|
||
repeat:
|
||
|
||
if (x == 0)
|
||
return 1;
|
||
|
||
code = GET_CODE (x);
|
||
switch (code)
|
||
{
|
||
case PC:
|
||
case CC0:
|
||
case CONST:
|
||
case CONST_INT:
|
||
case CONST_DOUBLE:
|
||
case SYMBOL_REF:
|
||
case LABEL_REF:
|
||
case ADDR_VEC:
|
||
case ADDR_DIFF_VEC:
|
||
return 1;
|
||
|
||
case MEM:
|
||
if (mem_last_set != 0)
|
||
return 0;
|
||
x = XEXP (x, 0);
|
||
goto repeat;
|
||
|
||
case REG:
|
||
return ! TEST_BIT (reg_set_bitmap, REGNO (x));
|
||
|
||
default:
|
||
break;
|
||
}
|
||
|
||
fmt = GET_RTX_FORMAT (code);
|
||
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
|
||
{
|
||
if (fmt[i] == 'e')
|
||
{
|
||
int not_set_p;
|
||
/* 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;
|
||
}
|
||
not_set_p = oprs_not_set_p (XEXP (x, i), insn);
|
||
if (! not_set_p)
|
||
return 0;
|
||
}
|
||
else if (fmt[i] == 'E')
|
||
{
|
||
int j;
|
||
for (j = 0; j < XVECLEN (x, i); j++)
|
||
{
|
||
int not_set_p = oprs_not_set_p (XVECEXP (x, i, j), insn);
|
||
if (! not_set_p)
|
||
return 0;
|
||
}
|
||
}
|
||
}
|
||
|
||
return 1;
|
||
}
|
||
|
||
/* Mark things set by a CALL. */
|
||
|
||
static void
|
||
mark_call (pat, insn)
|
||
rtx pat ATTRIBUTE_UNUSED, insn;
|
||
{
|
||
mem_last_set = INSN_CUID (insn);
|
||
}
|
||
|
||
/* Mark things set by a SET. */
|
||
|
||
static void
|
||
mark_set (pat, insn)
|
||
rtx pat, 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_BIT (reg_set_bitmap, REGNO (dest));
|
||
else if (GET_CODE (dest) == MEM)
|
||
mem_last_set = INSN_CUID (insn);
|
||
|
||
if (GET_CODE (SET_SRC (pat)) == CALL)
|
||
mark_call (SET_SRC (pat), insn);
|
||
}
|
||
|
||
/* Record things set by a CLOBBER. */
|
||
|
||
static void
|
||
mark_clobber (pat, insn)
|
||
rtx pat, 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_BIT (reg_set_bitmap, REGNO (clob));
|
||
else
|
||
mem_last_set = INSN_CUID (insn);
|
||
}
|
||
|
||
/* Record things set by INSN.
|
||
This data is used by oprs_not_set_p. */
|
||
|
||
static void
|
||
mark_oprs_set (insn)
|
||
rtx insn;
|
||
{
|
||
rtx pat = PATTERN (insn);
|
||
|
||
if (GET_CODE (pat) == SET)
|
||
mark_set (pat, insn);
|
||
else if (GET_CODE (pat) == PARALLEL)
|
||
{
|
||
int i;
|
||
|
||
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 (x, insn);
|
||
}
|
||
}
|
||
else if (GET_CODE (pat) == CLOBBER)
|
||
mark_clobber (pat, insn);
|
||
else if (GET_CODE (pat) == CALL)
|
||
mark_call (pat, insn);
|
||
}
|
||
|
||
/* Classic GCSE reaching definition support. */
|
||
|
||
/* Allocate reaching def variables. */
|
||
|
||
static void
|
||
alloc_rd_mem (n_blocks, n_insns)
|
||
int n_blocks, n_insns;
|
||
{
|
||
rd_kill = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns);
|
||
sbitmap_vector_zero (rd_kill, n_basic_blocks);
|
||
|
||
rd_gen = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns);
|
||
sbitmap_vector_zero (rd_gen, n_basic_blocks);
|
||
|
||
reaching_defs = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns);
|
||
sbitmap_vector_zero (reaching_defs, n_basic_blocks);
|
||
|
||
rd_out = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns);
|
||
sbitmap_vector_zero (rd_out, n_basic_blocks);
|
||
}
|
||
|
||
/* Free reaching def variables. */
|
||
|
||
static void
|
||
free_rd_mem ()
|
||
{
|
||
free (rd_kill);
|
||
free (rd_gen);
|
||
free (reaching_defs);
|
||
free (rd_out);
|
||
}
|
||
|
||
/* Add INSN to the kills of BB.
|
||
REGNO, set in BB, is killed by INSN. */
|
||
|
||
static void
|
||
handle_rd_kill_set (insn, regno, bb)
|
||
rtx insn;
|
||
int regno, bb;
|
||
{
|
||
struct reg_set *this_reg = reg_set_table[regno];
|
||
|
||
while (this_reg)
|
||
{
|
||
if (BLOCK_NUM (this_reg->insn) != BLOCK_NUM (insn))
|
||
SET_BIT (rd_kill[bb], INSN_CUID (this_reg->insn));
|
||
this_reg = this_reg->next;
|
||
}
|
||
}
|
||
|
||
void
|
||
dump_rd_table (file, title, bmap)
|
||
FILE *file;
|
||
char *title;
|
||
sbitmap *bmap;
|
||
{
|
||
int bb,cuid,i,j,n;
|
||
|
||
fprintf (file, "%s\n", title);
|
||
for (bb = 0; bb < n_basic_blocks; bb++)
|
||
{
|
||
fprintf (file, "BB %d\n", bb);
|
||
dump_sbitmap (file, bmap[bb]);
|
||
for (i = n = cuid = 0; i < bmap[bb]->size; i++)
|
||
{
|
||
for (j = 0; j < SBITMAP_ELT_BITS; j++, cuid++)
|
||
{
|
||
if ((bmap[bb]->elms[i] & (1 << j)) != 0)
|
||
{
|
||
if (n % 10 == 0)
|
||
fprintf (file, " ");
|
||
fprintf (file, " %d", INSN_UID (CUID_INSN (cuid)));
|
||
n++;
|
||
}
|
||
}
|
||
}
|
||
if (n != 0)
|
||
fprintf (file, "\n");
|
||
}
|
||
fprintf (file, "\n");
|
||
}
|
||
|
||
/* Compute the set of kill's for reaching definitions. */
|
||
|
||
static void
|
||
compute_kill_rd ()
|
||
{
|
||
int bb,cuid;
|
||
|
||
/* 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 (bb = 0; bb < n_basic_blocks; bb++)
|
||
{
|
||
for (cuid = 0; cuid < max_cuid; cuid++)
|
||
{
|
||
if (TEST_BIT (rd_gen[bb], cuid))
|
||
{
|
||
rtx insn = CUID_INSN (cuid);
|
||
rtx pat = PATTERN (insn);
|
||
|
||
if (GET_CODE (insn) == CALL_INSN)
|
||
{
|
||
int regno;
|
||
|
||
for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
|
||
{
|
||
if (call_used_regs[regno])
|
||
handle_rd_kill_set (insn, regno, bb);
|
||
}
|
||
}
|
||
|
||
if (GET_CODE (pat) == PARALLEL)
|
||
{
|
||
int i;
|
||
|
||
/* We work backwards because ... */
|
||
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)
|
||
{
|
||
if (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);
|
||
}
|
||
}
|
||
/* FIXME: CLOBBER? */
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
/* 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 ()
|
||
{
|
||
int bb, changed, passes;
|
||
|
||
for (bb = 0; bb < n_basic_blocks; bb++)
|
||
sbitmap_copy (rd_out[bb] /*dst*/, rd_gen[bb] /*src*/);
|
||
|
||
passes = 0;
|
||
changed = 1;
|
||
while (changed)
|
||
{
|
||
changed = 0;
|
||
for (bb = 0; bb < n_basic_blocks; bb++)
|
||
{
|
||
sbitmap_union_of_predecessors (reaching_defs[bb], rd_out,
|
||
bb, s_preds);
|
||
changed |= sbitmap_union_of_diff (rd_out[bb], rd_gen[bb],
|
||
reaching_defs[bb], rd_kill[bb]);
|
||
}
|
||
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 (n_blocks, n_exprs)
|
||
int n_blocks, n_exprs;
|
||
{
|
||
ae_kill = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
sbitmap_vector_zero (ae_kill, n_basic_blocks);
|
||
|
||
ae_gen = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
sbitmap_vector_zero (ae_gen, n_basic_blocks);
|
||
|
||
ae_in = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
sbitmap_vector_zero (ae_in, n_basic_blocks);
|
||
|
||
ae_out = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
sbitmap_vector_zero (ae_out, n_basic_blocks);
|
||
|
||
u_bitmap = (sbitmap) sbitmap_alloc (n_exprs);
|
||
sbitmap_ones (u_bitmap);
|
||
}
|
||
|
||
static void
|
||
free_avail_expr_mem ()
|
||
{
|
||
free (ae_kill);
|
||
free (ae_gen);
|
||
free (ae_in);
|
||
free (ae_out);
|
||
free (u_bitmap);
|
||
}
|
||
|
||
/* Compute the set of available expressions generated in each basic block. */
|
||
|
||
static void
|
||
compute_ae_gen ()
|
||
{
|
||
int i;
|
||
|
||
/* 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++)
|
||
{
|
||
struct expr *expr = expr_hash_table[i];
|
||
while (expr != NULL)
|
||
{
|
||
struct occr *occr = expr->avail_occr;
|
||
while (occr != NULL)
|
||
{
|
||
SET_BIT (ae_gen[BLOCK_NUM (occr->insn)], expr->bitmap_index);
|
||
occr = occr->next;
|
||
}
|
||
expr = expr->next_same_hash;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Return non-zero if expression X is killed in BB. */
|
||
|
||
static int
|
||
expr_killed_p (x, bb)
|
||
rtx x;
|
||
int bb;
|
||
{
|
||
int i;
|
||
enum rtx_code code;
|
||
char *fmt;
|
||
|
||
/* repeat is used to turn tail-recursion into iteration. */
|
||
repeat:
|
||
|
||
if (x == 0)
|
||
return 1;
|
||
|
||
code = GET_CODE (x);
|
||
switch (code)
|
||
{
|
||
case REG:
|
||
return TEST_BIT (reg_set_in_block[bb], REGNO (x));
|
||
|
||
case MEM:
|
||
if (mem_set_in_block[bb])
|
||
return 1;
|
||
x = XEXP (x, 0);
|
||
goto repeat;
|
||
|
||
case PC:
|
||
case CC0: /*FIXME*/
|
||
case CONST:
|
||
case CONST_INT:
|
||
case CONST_DOUBLE:
|
||
case SYMBOL_REF:
|
||
case LABEL_REF:
|
||
case ADDR_VEC:
|
||
case ADDR_DIFF_VEC:
|
||
return 0;
|
||
|
||
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.
|
||
This function is called enough to be worth it. */
|
||
if (i == 0)
|
||
{
|
||
x = tem;
|
||
goto repeat;
|
||
}
|
||
if (expr_killed_p (tem, bb))
|
||
return 1;
|
||
}
|
||
else if (fmt[i] == 'E')
|
||
{
|
||
int j;
|
||
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 ()
|
||
{
|
||
int bb,i;
|
||
|
||
for (bb = 0; bb < n_basic_blocks; bb++)
|
||
{
|
||
for (i = 0; i < expr_hash_table_size; i++)
|
||
{
|
||
struct expr *expr = expr_hash_table[i];
|
||
|
||
for ( ; expr != NULL; expr = expr->next_same_hash)
|
||
{
|
||
/* Skip EXPR if generated in this block. */
|
||
if (TEST_BIT (ae_gen[bb], expr->bitmap_index))
|
||
continue;
|
||
|
||
if (expr_killed_p (expr->expr, bb))
|
||
SET_BIT (ae_kill[bb], expr->bitmap_index);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Compute available expressions.
|
||
|
||
Implement the algorithm to find available expressions
|
||
as given in the Aho Sethi Ullman book, pages 627-631. */
|
||
|
||
static void
|
||
compute_available ()
|
||
{
|
||
int bb, changed, passes;
|
||
|
||
sbitmap_zero (ae_in[0]);
|
||
|
||
sbitmap_copy (ae_out[0] /*dst*/, ae_gen[0] /*src*/);
|
||
|
||
for (bb = 1; bb < n_basic_blocks; bb++)
|
||
sbitmap_difference (ae_out[bb], u_bitmap, ae_kill[bb]);
|
||
|
||
passes = 0;
|
||
changed = 1;
|
||
while (changed)
|
||
{
|
||
changed = 0;
|
||
for (bb = 1; bb < n_basic_blocks; bb++)
|
||
{
|
||
sbitmap_intersect_of_predecessors (ae_in[bb], ae_out,
|
||
bb, s_preds);
|
||
changed |= sbitmap_union_of_diff (ae_out[bb], ae_gen[bb],
|
||
ae_in[bb], ae_kill[bb]);
|
||
}
|
||
passes++;
|
||
}
|
||
|
||
if (gcse_file)
|
||
fprintf (gcse_file, "avail expr computation: %d passes\n", passes);
|
||
}
|
||
|
||
/* Actually perform the Classic GCSE optimizations. */
|
||
|
||
/* Return non-zero if occurrence OCCR of expression EXPR reaches block BB.
|
||
|
||
CHECK_SELF_LOOP is non-zero 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 (occr, expr, bb, check_self_loop, visited)
|
||
struct occr *occr;
|
||
struct expr *expr;
|
||
int bb;
|
||
int check_self_loop;
|
||
char *visited;
|
||
{
|
||
int_list_ptr pred;
|
||
|
||
if (visited == NULL)
|
||
{
|
||
visited = (char *) alloca (n_basic_blocks);
|
||
bzero (visited, n_basic_blocks);
|
||
}
|
||
|
||
for (pred = s_preds[bb]; pred != NULL; pred = pred->next)
|
||
{
|
||
int pred_bb = INT_LIST_VAL (pred);
|
||
|
||
if (visited[pred_bb])
|
||
{
|
||
/* 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], expr->bitmap_index)
|
||
&& BLOCK_NUM (occr->insn) == pred_bb)
|
||
return 1;
|
||
visited[pred_bb] = 1;
|
||
}
|
||
/* Ignore this predecessor if it kills the expression. */
|
||
else if (TEST_BIT (ae_kill[pred_bb], expr->bitmap_index))
|
||
visited[pred_bb] = 1;
|
||
/* Does this predecessor generate this expression? */
|
||
else if (TEST_BIT (ae_gen[pred_bb], 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)
|
||
return 1;
|
||
visited[pred_bb] = 1;
|
||
}
|
||
/* Neither gen nor kill. */
|
||
else
|
||
{
|
||
visited[pred_bb] = 1;
|
||
if (expr_reaches_here_p (occr, expr, pred_bb, check_self_loop, visited))
|
||
return 1;
|
||
}
|
||
}
|
||
|
||
/* All paths have been checked. */
|
||
return 0;
|
||
}
|
||
|
||
/* 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 (expr, insn)
|
||
struct expr *expr;
|
||
rtx insn;
|
||
{
|
||
int bb = BLOCK_NUM (insn);
|
||
|
||
if (expr->avail_occr->next == NULL)
|
||
{
|
||
if (BLOCK_NUM (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_NUM (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))
|
||
{
|
||
if (expr_reaches_here_p (occr, expr, bb, 1, NULL))
|
||
{
|
||
can_reach++;
|
||
if (can_reach > 1)
|
||
return NULL;
|
||
insn_computes_expr = occr->insn;
|
||
}
|
||
}
|
||
}
|
||
else /* Computation of the pattern outside this block. */
|
||
{
|
||
if (expr_reaches_here_p (occr, expr, bb, 0, NULL))
|
||
{
|
||
can_reach++;
|
||
if (can_reach > 1)
|
||
return NULL;
|
||
insn_computes_expr = occr->insn;
|
||
}
|
||
}
|
||
}
|
||
|
||
if (insn_computes_expr == NULL)
|
||
abort ();
|
||
return insn_computes_expr;
|
||
}
|
||
}
|
||
|
||
/* Return non-zero if the definition in DEF_INSN can reach INSN.
|
||
Only called by can_disregard_other_sets. */
|
||
|
||
static int
|
||
def_reaches_here_p (insn, def_insn)
|
||
rtx insn, 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;
|
||
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 non-zero 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 (addr_this_reg, insn, for_combine)
|
||
struct reg_set **addr_this_reg;
|
||
rtx insn;
|
||
int for_combine;
|
||
{
|
||
int number_of_reaching_defs = 0;
|
||
struct reg_set *this_reg = *addr_this_reg;
|
||
|
||
while (this_reg)
|
||
{
|
||
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;
|
||
if (! rtx_equal_p (SET_SRC (PATTERN (this_reg->insn)),
|
||
SET_SRC (PATTERN (insn))))
|
||
return 0;
|
||
}
|
||
*addr_this_reg = this_reg;
|
||
}
|
||
|
||
/* prev_this_reg = this_reg; */
|
||
this_reg = this_reg->next;
|
||
}
|
||
|
||
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 non-zero if any changes were made. */
|
||
|
||
static int
|
||
handle_avail_expr (insn, expr)
|
||
rtx insn;
|
||
struct expr *expr;
|
||
{
|
||
rtx pat, insn_computes_expr;
|
||
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;
|
||
|
||
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 (PATTERN (insn_computes_expr))) == REG)
|
||
{
|
||
/* This is the case when the available expression that reaches
|
||
here has already been handled as an available expression. */
|
||
int regnum_for_replacing = REGNO (SET_SRC (PATTERN (insn_computes_expr)));
|
||
/* 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)
|
||
{
|
||
int regnum_for_replacing = REGNO (SET_DEST (PATTERN (insn_computes_expr)));
|
||
/* 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 (PATTERN (insn_computes_expr));
|
||
else
|
||
to = SET_DEST (PATTERN (insn_computes_expr));
|
||
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 reg %d %s insn %d\n",
|
||
INSN_UID (insn), 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 (PATTERN (insn_computes_expr))));
|
||
|
||
/* 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 (PATTERN (insn_computes_expr))),
|
||
insn_computes_expr);
|
||
/* Keep block number table up to date. */
|
||
set_block_num (new_insn, BLOCK_NUM (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, computed in insn %d,\n",
|
||
INSN_UID (NEXT_INSN (insn_computes_expr)),
|
||
REGNO (SET_SRC (PATTERN (NEXT_INSN (insn_computes_expr)))),
|
||
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 set in insn %d\n",
|
||
INSN_UID (insn),
|
||
REGNO (SET_DEST (PATTERN (NEXT_INSN (insn_computes_expr)))),
|
||
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 non-zero if a change was made. */
|
||
|
||
static int
|
||
classic_gcse ()
|
||
{
|
||
int bb, changed;
|
||
rtx insn;
|
||
|
||
/* Note we start at block 1. */
|
||
|
||
changed = 0;
|
||
for (bb = 1; bb < n_basic_blocks; bb++)
|
||
{
|
||
/* Reset tables used to keep track of what's still valid [since the
|
||
start of the block]. */
|
||
reset_opr_set_tables ();
|
||
|
||
for (insn = basic_block_head[bb];
|
||
insn != NULL && insn != NEXT_INSN (basic_block_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)) != NULL)
|
||
/* Is the expression available [at the start of the
|
||
block]? */
|
||
&& TEST_BIT (ae_in[bb], 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 (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
|
||
mark_oprs_set (insn);
|
||
}
|
||
}
|
||
|
||
return changed;
|
||
}
|
||
|
||
/* Top level routine to perform one classic GCSE pass.
|
||
|
||
Return non-zero if a change was made. */
|
||
|
||
static int
|
||
one_classic_gcse_pass (f, pass)
|
||
rtx f;
|
||
int pass;
|
||
{
|
||
int changed = 0;
|
||
|
||
gcse_subst_count = 0;
|
||
gcse_create_count = 0;
|
||
|
||
alloc_expr_hash_table (max_cuid);
|
||
alloc_rd_mem (n_basic_blocks, max_cuid);
|
||
compute_expr_hash_table (f);
|
||
if (gcse_file)
|
||
dump_hash_table (gcse_file, "Expression", expr_hash_table,
|
||
expr_hash_table_size, n_exprs);
|
||
if (n_exprs > 0)
|
||
{
|
||
compute_kill_rd ();
|
||
compute_rd ();
|
||
alloc_avail_expr_mem (n_basic_blocks, n_exprs);
|
||
compute_ae_gen ();
|
||
compute_ae_kill ();
|
||
compute_available ();
|
||
changed = classic_gcse ();
|
||
free_avail_expr_mem ();
|
||
}
|
||
free_rd_mem ();
|
||
free_expr_hash_table ();
|
||
|
||
if (gcse_file)
|
||
{
|
||
fprintf (gcse_file, "\n");
|
||
fprintf (gcse_file, "GCSE of %s, pass %d: %d bytes needed, %d substs, %d insns created\n",
|
||
current_function_name, pass,
|
||
bytes_used, gcse_subst_count, 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 (n_blocks, n_sets)
|
||
int n_blocks, 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 ()
|
||
{
|
||
free (cprop_pavloc);
|
||
free (cprop_absaltered);
|
||
free (cprop_avin);
|
||
free (cprop_avout);
|
||
}
|
||
|
||
/* Dump copy/const propagation data. */
|
||
|
||
void
|
||
dump_cprop_data (file)
|
||
FILE *file;
|
||
{
|
||
dump_sbitmap_vector (file, "CPROP partially locally available sets", "BB",
|
||
cprop_pavloc, n_basic_blocks);
|
||
dump_sbitmap_vector (file, "CPROP absolutely altered sets", "BB",
|
||
cprop_absaltered, n_basic_blocks);
|
||
|
||
dump_sbitmap_vector (file, "CPROP available incoming sets", "BB",
|
||
cprop_avin, n_basic_blocks);
|
||
dump_sbitmap_vector (file, "CPROP available outgoing sets", "BB",
|
||
cprop_avout, n_basic_blocks);
|
||
}
|
||
|
||
/* 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 (x, indx, bmap, set_p)
|
||
rtx x;
|
||
int indx;
|
||
sbitmap *bmap;
|
||
int set_p;
|
||
{
|
||
int bb,i;
|
||
enum rtx_code code;
|
||
char *fmt;
|
||
|
||
/* repeat is used to turn tail-recursion into iteration. */
|
||
repeat:
|
||
|
||
if (x == 0)
|
||
return;
|
||
|
||
code = GET_CODE (x);
|
||
switch (code)
|
||
{
|
||
case REG:
|
||
{
|
||
reg_set *r;
|
||
int regno = REGNO (x);
|
||
|
||
if (set_p)
|
||
{
|
||
if (regno < FIRST_PSEUDO_REGISTER)
|
||
{
|
||
for (bb = 0; bb < n_basic_blocks; bb++)
|
||
if (TEST_BIT (reg_set_in_block[bb], regno))
|
||
SET_BIT (bmap[bb], indx);
|
||
}
|
||
else
|
||
{
|
||
for (r = reg_set_table[regno]; r != NULL; r = r->next)
|
||
{
|
||
bb = BLOCK_NUM (r->insn);
|
||
SET_BIT (bmap[bb], indx);
|
||
}
|
||
}
|
||
}
|
||
else
|
||
{
|
||
if (regno < FIRST_PSEUDO_REGISTER)
|
||
{
|
||
for (bb = 0; bb < n_basic_blocks; bb++)
|
||
if (TEST_BIT (reg_set_in_block[bb], regno))
|
||
RESET_BIT (bmap[bb], indx);
|
||
}
|
||
else
|
||
{
|
||
for (r = reg_set_table[regno]; r != NULL; r = r->next)
|
||
{
|
||
bb = BLOCK_NUM (r->insn);
|
||
RESET_BIT (bmap[bb], indx);
|
||
}
|
||
}
|
||
}
|
||
return;
|
||
}
|
||
|
||
case MEM:
|
||
if (set_p)
|
||
{
|
||
for (bb = 0; bb < n_basic_blocks; bb++)
|
||
if (mem_set_in_block[bb])
|
||
SET_BIT (bmap[bb], indx);
|
||
}
|
||
else
|
||
{
|
||
for (bb = 0; bb < n_basic_blocks; bb++)
|
||
if (mem_set_in_block[bb])
|
||
RESET_BIT (bmap[bb], indx);
|
||
}
|
||
x = XEXP (x, 0);
|
||
goto repeat;
|
||
|
||
case PC:
|
||
case CC0: /*FIXME*/
|
||
case CONST:
|
||
case CONST_INT:
|
||
case CONST_DOUBLE:
|
||
case SYMBOL_REF:
|
||
case LABEL_REF:
|
||
case ADDR_VEC:
|
||
case ADDR_DIFF_VEC:
|
||
return;
|
||
|
||
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.
|
||
This function is called enough to be worth it. */
|
||
if (i == 0)
|
||
{
|
||
x = tem;
|
||
goto repeat;
|
||
}
|
||
compute_transp (tem, indx, bmap, set_p);
|
||
}
|
||
else if (fmt[i] == 'E')
|
||
{
|
||
int j;
|
||
for (j = 0; j < XVECLEN (x, i); j++)
|
||
compute_transp (XVECEXP (x, i, j), indx, bmap, set_p);
|
||
}
|
||
}
|
||
}
|
||
|
||
static void
|
||
compute_cprop_local_properties ()
|
||
{
|
||
int i;
|
||
|
||
sbitmap_vector_zero (cprop_absaltered, n_basic_blocks);
|
||
sbitmap_vector_zero (cprop_pavloc, n_basic_blocks);
|
||
|
||
for (i = 0; i < set_hash_table_size; i++)
|
||
{
|
||
struct expr *expr;
|
||
|
||
for (expr = set_hash_table[i]; expr != NULL; expr = expr->next_same_hash)
|
||
{
|
||
struct occr *occr;
|
||
int indx = expr->bitmap_index;
|
||
|
||
/* The assignment is absolutely altered if any operand is modified
|
||
by this block [excluding the assignment itself].
|
||
We start by assuming all are transparent [none are killed], and
|
||
then setting the bits for those that are. */
|
||
|
||
compute_transp (expr->expr, indx, cprop_absaltered, 1);
|
||
|
||
/* The occurrences recorded in avail_occr are exactly those that
|
||
we want to set to non-zero in PAVLOC. */
|
||
|
||
for (occr = expr->avail_occr; occr != NULL; occr = occr->next)
|
||
{
|
||
int bb = BLOCK_NUM (occr->insn);
|
||
SET_BIT (cprop_pavloc[bb], indx);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
static void
|
||
compute_cprop_avinout ()
|
||
{
|
||
int bb, changed, passes;
|
||
|
||
sbitmap_zero (cprop_avin[0]);
|
||
sbitmap_vector_ones (cprop_avout, n_basic_blocks);
|
||
|
||
passes = 0;
|
||
changed = 1;
|
||
while (changed)
|
||
{
|
||
changed = 0;
|
||
for (bb = 0; bb < n_basic_blocks; bb++)
|
||
{
|
||
if (bb != 0)
|
||
sbitmap_intersect_of_predecessors (cprop_avin[bb], cprop_avout,
|
||
bb, s_preds);
|
||
changed |= sbitmap_union_of_diff (cprop_avout[bb],
|
||
cprop_pavloc[bb],
|
||
cprop_avin[bb],
|
||
cprop_absaltered[bb]);
|
||
}
|
||
passes++;
|
||
}
|
||
|
||
if (gcse_file)
|
||
fprintf (gcse_file, "cprop avail expr computation: %d passes\n", passes);
|
||
}
|
||
|
||
/* Top level routine to do the dataflow analysis needed by copy/const
|
||
propagation. */
|
||
|
||
static void
|
||
compute_cprop_data ()
|
||
{
|
||
compute_cprop_local_properties ();
|
||
compute_cprop_avinout ();
|
||
}
|
||
|
||
/* Copy/constant propagation. */
|
||
|
||
struct reg_use {
|
||
rtx reg_rtx;
|
||
};
|
||
|
||
/* 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 (x)
|
||
rtx x;
|
||
{
|
||
int i;
|
||
enum rtx_code code;
|
||
char *fmt;
|
||
|
||
/* repeat is used to turn tail-recursion into iteration. */
|
||
repeat:
|
||
|
||
if (x == 0)
|
||
return;
|
||
|
||
code = GET_CODE (x);
|
||
switch (code)
|
||
{
|
||
case REG:
|
||
if (reg_use_count == MAX_USES)
|
||
return;
|
||
reg_use_table[reg_use_count].reg_rtx = x;
|
||
reg_use_count++;
|
||
return;
|
||
|
||
case MEM:
|
||
x = XEXP (x, 0);
|
||
goto repeat;
|
||
|
||
case PC:
|
||
case CC0:
|
||
case CONST:
|
||
case CONST_INT:
|
||
case CONST_DOUBLE:
|
||
case SYMBOL_REF:
|
||
case LABEL_REF:
|
||
case CLOBBER:
|
||
case ADDR_VEC:
|
||
case ADDR_DIFF_VEC:
|
||
case ASM_INPUT: /*FIXME*/
|
||
return;
|
||
|
||
case SET:
|
||
if (GET_CODE (SET_DEST (x)) == MEM)
|
||
find_used_regs (SET_DEST (x));
|
||
x = SET_SRC (x);
|
||
goto repeat;
|
||
|
||
default:
|
||
break;
|
||
}
|
||
|
||
/* Recursively scan the operands of this expression. */
|
||
|
||
fmt = GET_RTX_FORMAT (code);
|
||
for (i = GET_RTX_LENGTH (code) - 1; 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));
|
||
}
|
||
else if (fmt[i] == 'E')
|
||
{
|
||
int j;
|
||
for (j = 0; j < XVECLEN (x, i); j++)
|
||
find_used_regs (XVECEXP (x, i, j));
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Try to replace all non-SET_DEST occurrences of FROM in INSN with TO.
|
||
Returns non-zero is successful. */
|
||
|
||
static int
|
||
try_replace_reg (from, to, insn)
|
||
rtx from, to, insn;
|
||
{
|
||
return validate_replace_src (from, to, insn);
|
||
}
|
||
|
||
/* Find a set of REGNO that is available on entry to INSN's block.
|
||
Returns NULL if not found. */
|
||
|
||
static struct expr *
|
||
find_avail_set (regno, insn)
|
||
int regno;
|
||
rtx insn;
|
||
{
|
||
struct expr *set = lookup_set (regno, NULL_RTX);
|
||
|
||
while (set)
|
||
{
|
||
if (TEST_BIT (cprop_avin[BLOCK_NUM (insn)], set->bitmap_index))
|
||
break;
|
||
set = next_set (regno, set);
|
||
}
|
||
|
||
return set;
|
||
}
|
||
|
||
/* Perform constant and copy propagation on INSN.
|
||
The result is non-zero if a change was made. */
|
||
|
||
static int
|
||
cprop_insn (insn)
|
||
rtx insn;
|
||
{
|
||
struct reg_use *reg_used;
|
||
int changed = 0;
|
||
|
||
/* ??? For now only propagate into SETs. */
|
||
if (GET_CODE (insn) != INSN
|
||
|| GET_CODE (PATTERN (insn)) != SET)
|
||
return 0;
|
||
|
||
reg_use_count = 0;
|
||
find_used_regs (PATTERN (insn));
|
||
|
||
reg_used = ®_use_table[0];
|
||
for ( ; reg_use_count > 0; reg_used++, reg_use_count--)
|
||
{
|
||
rtx pat, src;
|
||
struct expr *set;
|
||
int regno = REGNO (reg_used->reg_rtx);
|
||
|
||
/* 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);
|
||
|
||
if (GET_CODE (src) == CONST_INT)
|
||
{
|
||
if (try_replace_reg (reg_used->reg_rtx, src, insn))
|
||
{
|
||
changed = 1;
|
||
const_prop_count++;
|
||
if (gcse_file != NULL)
|
||
{
|
||
fprintf (gcse_file, "CONST-PROP: Replacing reg %d in insn %d with constant ",
|
||
regno, INSN_UID (insn));
|
||
fprintf (gcse_file, HOST_WIDE_INT_PRINT_DEC, INTVAL (src));
|
||
fprintf (gcse_file, "\n");
|
||
}
|
||
|
||
/* The original insn setting reg_used may or may not now be
|
||
deletable. We leave the deletion to flow. */
|
||
}
|
||
}
|
||
else if (GET_CODE (src) == REG
|
||
&& REGNO (src) >= FIRST_PSEUDO_REGISTER
|
||
&& REGNO (src) != regno)
|
||
{
|
||
/* We know the set is available.
|
||
Now check that SET_SRC is ANTLOC (i.e. none of the source operands
|
||
have changed since the start of the block). */
|
||
if (oprs_not_set_p (src, insn))
|
||
{
|
||
if (try_replace_reg (reg_used->reg_rtx, src, insn))
|
||
{
|
||
changed = 1;
|
||
copy_prop_count++;
|
||
if (gcse_file != NULL)
|
||
{
|
||
fprintf (gcse_file, "COPY-PROP: Replacing reg %d in insn %d with reg %d\n",
|
||
regno, INSN_UID (insn), 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;
|
||
}
|
||
|
||
/* Forward propagate copies.
|
||
This includes copies and constants.
|
||
Return non-zero if a change was made. */
|
||
|
||
static int
|
||
cprop ()
|
||
{
|
||
int bb, changed;
|
||
rtx insn;
|
||
|
||
/* Note we start at block 1. */
|
||
|
||
changed = 0;
|
||
for (bb = 1; bb < n_basic_blocks; bb++)
|
||
{
|
||
/* Reset tables used to keep track of what's still valid [since the
|
||
start of the block]. */
|
||
reset_opr_set_tables ();
|
||
|
||
for (insn = basic_block_head[bb];
|
||
insn != NULL && insn != NEXT_INSN (basic_block_end[bb]);
|
||
insn = NEXT_INSN (insn))
|
||
{
|
||
if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
|
||
{
|
||
changed |= cprop_insn (insn);
|
||
|
||
/* Keep track of everything modified by this insn. */
|
||
/* ??? Need to be careful w.r.t. mods done to INSN. */
|
||
mark_oprs_set (insn);
|
||
}
|
||
}
|
||
}
|
||
|
||
if (gcse_file != NULL)
|
||
fprintf (gcse_file, "\n");
|
||
|
||
return changed;
|
||
}
|
||
|
||
/* Perform one copy/constant propagation pass.
|
||
F is the first insn in the function.
|
||
PASS is the pass count. */
|
||
|
||
static int
|
||
one_cprop_pass (f, pass)
|
||
rtx f;
|
||
int pass;
|
||
{
|
||
int changed = 0;
|
||
|
||
const_prop_count = 0;
|
||
copy_prop_count = 0;
|
||
|
||
alloc_set_hash_table (max_cuid);
|
||
compute_set_hash_table (f);
|
||
if (gcse_file)
|
||
dump_hash_table (gcse_file, "SET", set_hash_table, set_hash_table_size,
|
||
n_sets);
|
||
if (n_sets > 0)
|
||
{
|
||
alloc_cprop_mem (n_basic_blocks, n_sets);
|
||
compute_cprop_data ();
|
||
changed = cprop ();
|
||
free_cprop_mem ();
|
||
}
|
||
free_set_hash_table ();
|
||
|
||
if (gcse_file)
|
||
{
|
||
fprintf (gcse_file, "CPROP of %s, pass %d: %d bytes needed, %d const props, %d copy props\n",
|
||
current_function_name, pass,
|
||
bytes_used, const_prop_count, copy_prop_count);
|
||
fprintf (gcse_file, "\n");
|
||
}
|
||
|
||
return changed;
|
||
}
|
||
|
||
/* Compute PRE working variables. */
|
||
|
||
/* Local properties of expressions. */
|
||
/* Nonzero for expressions that are transparent in the block. */
|
||
static sbitmap *pre_transp;
|
||
/* Nonzero for expressions that are computed (available) in the block. */
|
||
static sbitmap *pre_comp;
|
||
/* Nonzero for expressions that are locally anticipatable in the block. */
|
||
static sbitmap *pre_antloc;
|
||
|
||
/* Global properties (computed from the expression local properties). */
|
||
/* Nonzero for expressions that are available on block entry/exit. */
|
||
static sbitmap *pre_avin;
|
||
static sbitmap *pre_avout;
|
||
/* Nonzero for expressions that are anticipatable on block entry/exit. */
|
||
static sbitmap *pre_antin;
|
||
static sbitmap *pre_antout;
|
||
/* Nonzero for expressions that are partially available on block entry/exit. */
|
||
static sbitmap *pre_pavin;
|
||
static sbitmap *pre_pavout;
|
||
/* Nonzero for expressions that are "placement possible" on block entry/exit. */
|
||
static sbitmap *pre_ppin;
|
||
static sbitmap *pre_ppout;
|
||
|
||
/* Used while performing PRE to denote which insns are redundant. */
|
||
static sbitmap pre_redundant;
|
||
|
||
/* Allocate vars used for PRE analysis. */
|
||
|
||
static void
|
||
alloc_pre_mem (n_blocks, n_exprs)
|
||
int n_blocks, n_exprs;
|
||
{
|
||
pre_transp = sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
pre_comp = sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
pre_antloc = sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
|
||
pre_avin = sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
pre_avout = sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
pre_antin = sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
pre_antout = sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
|
||
pre_pavin = sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
pre_pavout = sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
pre_ppin = sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
pre_ppout = sbitmap_vector_alloc (n_blocks, n_exprs);
|
||
}
|
||
|
||
/* Free vars used for PRE analysis. */
|
||
|
||
static void
|
||
free_pre_mem ()
|
||
{
|
||
free (pre_transp);
|
||
free (pre_comp);
|
||
free (pre_antloc);
|
||
|
||
free (pre_avin);
|
||
free (pre_avout);
|
||
free (pre_antin);
|
||
free (pre_antout);
|
||
|
||
free (pre_pavin);
|
||
free (pre_pavout);
|
||
free (pre_ppin);
|
||
free (pre_ppout);
|
||
}
|
||
|
||
/* Dump PRE data. */
|
||
|
||
void
|
||
dump_pre_data (file)
|
||
FILE *file;
|
||
{
|
||
dump_sbitmap_vector (file, "PRE locally transparent expressions", "BB",
|
||
pre_transp, n_basic_blocks);
|
||
dump_sbitmap_vector (file, "PRE locally available expressions", "BB",
|
||
pre_comp, n_basic_blocks);
|
||
dump_sbitmap_vector (file, "PRE locally anticipatable expressions", "BB",
|
||
pre_antloc, n_basic_blocks);
|
||
|
||
dump_sbitmap_vector (file, "PRE available incoming expressions", "BB",
|
||
pre_avin, n_basic_blocks);
|
||
dump_sbitmap_vector (file, "PRE available outgoing expressions", "BB",
|
||
pre_avout, n_basic_blocks);
|
||
dump_sbitmap_vector (file, "PRE anticipatable incoming expressions", "BB",
|
||
pre_antin, n_basic_blocks);
|
||
dump_sbitmap_vector (file, "PRE anticipatable outgoing expressions", "BB",
|
||
pre_antout, n_basic_blocks);
|
||
|
||
dump_sbitmap_vector (file, "PRE partially available incoming expressions", "BB",
|
||
pre_pavin, n_basic_blocks);
|
||
dump_sbitmap_vector (file, "PRE partially available outgoing expressions", "BB",
|
||
pre_pavout, n_basic_blocks);
|
||
dump_sbitmap_vector (file, "PRE placement possible on incoming", "BB",
|
||
pre_ppin, n_basic_blocks);
|
||
dump_sbitmap_vector (file, "PRE placement possible on outgoing", "BB",
|
||
pre_ppout, n_basic_blocks);
|
||
}
|
||
|
||
/* 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. */
|
||
|
||
static void
|
||
compute_pre_local_properties ()
|
||
{
|
||
int i;
|
||
|
||
sbitmap_vector_ones (pre_transp, n_basic_blocks);
|
||
sbitmap_vector_zero (pre_comp, n_basic_blocks);
|
||
sbitmap_vector_zero (pre_antloc, n_basic_blocks);
|
||
|
||
for (i = 0; i < expr_hash_table_size; i++)
|
||
{
|
||
struct expr *expr;
|
||
|
||
for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash)
|
||
{
|
||
struct occr *occr;
|
||
int indx = expr->bitmap_index;
|
||
|
||
/* 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. */
|
||
|
||
compute_transp (expr->expr, indx, pre_transp, 0);
|
||
|
||
/* The occurrences recorded in antic_occr are exactly those that
|
||
we want to set to non-zero in ANTLOC. */
|
||
|
||
for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
|
||
{
|
||
int bb = BLOCK_NUM (occr->insn);
|
||
SET_BIT (pre_antloc[bb], 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 non-zero in COMP. */
|
||
|
||
for (occr = expr->avail_occr; occr != NULL; occr = occr->next)
|
||
{
|
||
int bb = BLOCK_NUM (occr->insn);
|
||
SET_BIT (pre_comp[bb], 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;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Compute expression availability at entrance and exit of each block. */
|
||
|
||
static void
|
||
compute_pre_avinout ()
|
||
{
|
||
int bb, changed, passes;
|
||
|
||
sbitmap_zero (pre_avin[0]);
|
||
sbitmap_vector_ones (pre_avout, n_basic_blocks);
|
||
|
||
passes = 0;
|
||
changed = 1;
|
||
while (changed)
|
||
{
|
||
changed = 0;
|
||
for (bb = 0; bb < n_basic_blocks; bb++)
|
||
{
|
||
if (bb != 0)
|
||
sbitmap_intersect_of_predecessors (pre_avin[bb], pre_avout,
|
||
bb, s_preds);
|
||
changed |= sbitmap_a_or_b_and_c (pre_avout[bb], pre_comp[bb],
|
||
pre_transp[bb], pre_avin[bb]);
|
||
}
|
||
passes++;
|
||
}
|
||
|
||
if (gcse_file)
|
||
fprintf (gcse_file, "avail expr computation: %d passes\n", passes);
|
||
}
|
||
|
||
/* Compute expression anticipatability at entrance and exit of each block. */
|
||
|
||
static void
|
||
compute_pre_antinout ()
|
||
{
|
||
int bb, changed, passes;
|
||
|
||
sbitmap_zero (pre_antout[n_basic_blocks - 1]);
|
||
sbitmap_vector_ones (pre_antin, n_basic_blocks);
|
||
|
||
passes = 0;
|
||
changed = 1;
|
||
while (changed)
|
||
{
|
||
changed = 0;
|
||
/* We scan the blocks in the reverse order to speed up
|
||
the convergence. */
|
||
for (bb = n_basic_blocks - 1; bb >= 0; bb--)
|
||
{
|
||
if (bb != n_basic_blocks - 1)
|
||
sbitmap_intersect_of_successors (pre_antout[bb], pre_antin,
|
||
bb, s_succs);
|
||
changed |= sbitmap_a_or_b_and_c (pre_antin[bb], pre_antloc[bb],
|
||
pre_transp[bb], pre_antout[bb]);
|
||
}
|
||
passes++;
|
||
}
|
||
|
||
if (gcse_file)
|
||
fprintf (gcse_file, "antic expr computation: %d passes\n", passes);
|
||
}
|
||
|
||
/* Compute expression partial availability at entrance and exit of
|
||
each block. */
|
||
|
||
static void
|
||
compute_pre_pavinout ()
|
||
{
|
||
int bb, changed, passes;
|
||
|
||
sbitmap_zero (pre_pavin[0]);
|
||
sbitmap_vector_zero (pre_pavout, n_basic_blocks);
|
||
|
||
passes = 0;
|
||
changed = 1;
|
||
while (changed)
|
||
{
|
||
changed = 0;
|
||
for (bb = 0; bb < n_basic_blocks; bb++)
|
||
{
|
||
if (bb != 0)
|
||
sbitmap_union_of_predecessors (pre_pavin[bb], pre_pavout,
|
||
bb, s_preds);
|
||
changed |= sbitmap_a_or_b_and_c (pre_pavout[bb], pre_comp[bb],
|
||
pre_transp[bb], pre_pavin[bb]);
|
||
}
|
||
passes++;
|
||
}
|
||
|
||
if (gcse_file)
|
||
fprintf (gcse_file, "partially avail expr computation: %d passes\n", passes);
|
||
}
|
||
|
||
/* Compute "placement possible" information on entrance and exit of
|
||
each block.
|
||
|
||
From Fred Chow's Thesis:
|
||
A computation `e' is PP at a point `p' if it is anticipated at `p' and
|
||
all the anticipated e's can be rendered redundant by zero or more
|
||
insertions at that point and some other points in the procedure, and
|
||
these insertions satisfy the conditions that the insertions are always
|
||
at points that `e' is anticipated and the first anticipated e's after the
|
||
insertions are rendered redundant. */
|
||
|
||
static void
|
||
compute_pre_ppinout ()
|
||
{
|
||
int bb, i, changed, size, passes;
|
||
|
||
sbitmap_vector_ones (pre_ppin, n_basic_blocks);
|
||
/* ??? Inefficient as we set pre_ppin[0] twice, but simple. */
|
||
sbitmap_zero (pre_ppin[0]);
|
||
|
||
sbitmap_vector_ones (pre_ppout, n_basic_blocks);
|
||
/* ??? Inefficient as we set pre_ppout[n_basic_blocks-1] twice, but simple. */
|
||
sbitmap_zero (pre_ppout[n_basic_blocks - 1]);
|
||
|
||
size = pre_ppin[0]->size;
|
||
passes = 0;
|
||
changed = 1;
|
||
while (changed)
|
||
{
|
||
changed = 0;
|
||
for (bb = 1; bb < n_basic_blocks; bb++)
|
||
{
|
||
sbitmap_ptr antin = pre_antin[bb]->elms;
|
||
sbitmap_ptr pavin = pre_pavin[bb]->elms;
|
||
sbitmap_ptr antloc = pre_antloc[bb]->elms;
|
||
sbitmap_ptr transp = pre_transp[bb]->elms;
|
||
sbitmap_ptr ppout = pre_ppout[bb]->elms;
|
||
sbitmap_ptr ppin = pre_ppin[bb]->elms;
|
||
|
||
for (i = 0; i < size; i++)
|
||
{
|
||
int_list_ptr pred;
|
||
SBITMAP_ELT_TYPE tmp = *antin & *pavin & (*antloc | (*transp & *ppout));
|
||
SBITMAP_ELT_TYPE pred_val = -1L;
|
||
|
||
for (pred = s_preds[bb]; pred != NULL; pred = pred->next)
|
||
{
|
||
int pred_bb = INT_LIST_VAL (pred);
|
||
sbitmap_ptr ppout_j,avout_j;
|
||
|
||
if (pred_bb == ENTRY_BLOCK)
|
||
continue;
|
||
|
||
/* If this is a back edge, propagate info along the back
|
||
edge to allow for loop invariant code motion.
|
||
|
||
See FOLLOW_BACK_EDGES at the top of this file for a longer
|
||
discussion about loop invariant code motion in pre. */
|
||
if (! FOLLOW_BACK_EDGES
|
||
&& (INSN_CUID (BLOCK_HEAD (bb))
|
||
< INSN_CUID (BLOCK_END (pred_bb))))
|
||
{
|
||
pred_val = 0;
|
||
}
|
||
else
|
||
{
|
||
ppout_j = pre_ppout[pred_bb]->elms + i;
|
||
avout_j = pre_avout[pred_bb]->elms + i;
|
||
pred_val &= *ppout_j | *avout_j;
|
||
}
|
||
}
|
||
tmp &= pred_val;
|
||
*ppin = tmp;
|
||
antin++; pavin++; antloc++; transp++; ppout++; ppin++;
|
||
}
|
||
}
|
||
|
||
for (bb = 0; bb < n_basic_blocks - 1; bb++)
|
||
{
|
||
sbitmap_ptr ppout = pre_ppout[bb]->elms;
|
||
|
||
for (i = 0; i < size; i++)
|
||
{
|
||
int_list_ptr succ;
|
||
SBITMAP_ELT_TYPE tmp = -1L;
|
||
|
||
for (succ = s_succs[bb]; succ != NULL; succ = succ->next)
|
||
{
|
||
int succ_bb = INT_LIST_VAL (succ);
|
||
sbitmap_ptr ppin;
|
||
|
||
if (succ_bb == EXIT_BLOCK)
|
||
continue;
|
||
|
||
ppin = pre_ppin[succ_bb]->elms + i;
|
||
tmp &= *ppin;
|
||
}
|
||
if (*ppout != tmp)
|
||
{
|
||
changed = 1;
|
||
*ppout++ = tmp;
|
||
}
|
||
else
|
||
ppout++;
|
||
}
|
||
}
|
||
|
||
passes++;
|
||
}
|
||
|
||
if (gcse_file)
|
||
fprintf (gcse_file, "placement possible computation: %d passes\n", passes);
|
||
}
|
||
|
||
/* Top level routine to do the dataflow analysis needed by PRE. */
|
||
|
||
static void
|
||
compute_pre_data ()
|
||
{
|
||
compute_pre_local_properties ();
|
||
compute_pre_avinout ();
|
||
compute_pre_antinout ();
|
||
compute_pre_pavinout ();
|
||
compute_pre_ppinout ();
|
||
if (gcse_file)
|
||
fprintf (gcse_file, "\n");
|
||
}
|
||
|
||
/* PRE utilities */
|
||
|
||
/* Return non-zero if occurrence OCCR of expression EXPR reaches 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 (occr, expr, bb, visited)
|
||
struct occr *occr;
|
||
struct expr *expr;
|
||
int bb;
|
||
char *visited;
|
||
{
|
||
int_list_ptr pred;
|
||
|
||
if (visited == NULL)
|
||
{
|
||
visited = (char *) alloca (n_basic_blocks);
|
||
bzero (visited, n_basic_blocks);
|
||
}
|
||
|
||
for (pred = s_preds[bb]; pred != NULL; pred = pred->next)
|
||
{
|
||
int pred_bb = INT_LIST_VAL (pred);
|
||
|
||
if (pred_bb == ENTRY_BLOCK
|
||
/* Has predecessor has already been visited? */
|
||
|| visited[pred_bb])
|
||
{
|
||
/* Nothing to do. */
|
||
}
|
||
/* Does this predecessor generate this expression? */
|
||
else if (TEST_BIT (pre_comp[pred_bb], 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)
|
||
return 1;
|
||
visited[pred_bb] = 1;
|
||
}
|
||
/* Ignore this predecessor if it kills the expression. */
|
||
else if (! TEST_BIT (pre_transp[pred_bb], expr->bitmap_index))
|
||
visited[pred_bb] = 1;
|
||
/* Neither gen nor kill. */
|
||
else
|
||
{
|
||
visited[pred_bb] = 1;
|
||
if (pre_expr_reaches_here_p (occr, expr, pred_bb, visited))
|
||
return 1;
|
||
}
|
||
}
|
||
|
||
/* All paths have been checked. */
|
||
return 0;
|
||
}
|
||
|
||
/* Add EXPR to the end of basic block BB. */
|
||
|
||
static void
|
||
pre_insert_insn (expr, bb)
|
||
struct expr *expr;
|
||
int bb;
|
||
{
|
||
rtx insn = BLOCK_END (bb);
|
||
rtx new_insn;
|
||
rtx reg = expr->reaching_reg;
|
||
int regno = REGNO (reg);
|
||
rtx pat;
|
||
|
||
pat = gen_rtx_SET (VOIDmode, reg, copy_rtx (expr->expr));
|
||
|
||
/* If the last insn is a jump, insert EXPR in front [taking care to
|
||
handle cc0, etc. properly]. */
|
||
|
||
if (GET_CODE (insn) == JUMP_INSN)
|
||
{
|
||
#ifdef HAVE_cc0
|
||
rtx note;
|
||
#endif
|
||
|
||
/* 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
|
||
&& GET_RTX_CLASS (GET_CODE (maybe_cc0_setter)) == 'i'
|
||
&& 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 (pat, insn);
|
||
add_label_notes (SET_SRC (pat), new_insn);
|
||
if (BLOCK_HEAD (bb) == insn)
|
||
BLOCK_HEAD (bb) = new_insn;
|
||
/* Keep block number table up to date. */
|
||
set_block_num (new_insn, bb);
|
||
/* Keep register set table up to date. */
|
||
record_one_set (regno, new_insn);
|
||
}
|
||
else
|
||
{
|
||
new_insn = emit_insn_after (pat, insn);
|
||
add_label_notes (SET_SRC (pat), new_insn);
|
||
BLOCK_END (bb) = new_insn;
|
||
/* Keep block number table up to date. */
|
||
set_block_num (new_insn, bb);
|
||
/* Keep register set table up to date. */
|
||
record_one_set (regno, new_insn);
|
||
}
|
||
|
||
gcse_create_count++;
|
||
|
||
if (gcse_file)
|
||
{
|
||
fprintf (gcse_file, "PRE: end of bb %d, insn %d, copying expression %d to reg %d\n",
|
||
bb, INSN_UID (new_insn), expr->bitmap_index, regno);
|
||
}
|
||
}
|
||
|
||
/* Insert partially redundant expressions at the ends of appropriate basic
|
||
blocks making them now redundant. */
|
||
|
||
static void
|
||
pre_insert (index_map)
|
||
struct expr **index_map;
|
||
{
|
||
int bb, i, size;
|
||
|
||
/* Compute INSERT = PPOUT & (~AVOUT) & (~PPIN | ~TRANSP) for each
|
||
expression. Where INSERT == TRUE, add the expression at the end of
|
||
the basic block. */
|
||
|
||
size = pre_ppout[0]->size;
|
||
for (bb = 0; bb < n_basic_blocks; bb++)
|
||
{
|
||
int indx;
|
||
sbitmap_ptr ppout = pre_ppout[bb]->elms;
|
||
sbitmap_ptr avout = pre_avout[bb]->elms;
|
||
sbitmap_ptr ppin = pre_ppin[bb]->elms;
|
||
sbitmap_ptr transp = pre_transp[bb]->elms;
|
||
|
||
for (i = indx = 0;
|
||
i < size;
|
||
i++, indx += SBITMAP_ELT_BITS, ppout++, avout++, ppin++, transp++)
|
||
{
|
||
int j;
|
||
SBITMAP_ELT_TYPE insert = *ppout & (~*avout) & (~*ppin | ~*transp);
|
||
|
||
for (j = indx; insert != 0 && j < n_exprs; j++, insert >>= 1)
|
||
{
|
||
if ((insert & 1) != 0
|
||
/* 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. */
|
||
&& index_map[j]->reaching_reg != NULL)
|
||
pre_insert_insn (index_map[j], bb);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Copy the result of INSN to REG.
|
||
INDX is the expression number. */
|
||
|
||
static void
|
||
pre_insert_copy_insn (expr, insn)
|
||
struct expr *expr;
|
||
rtx insn;
|
||
{
|
||
rtx reg = expr->reaching_reg;
|
||
int regno = REGNO (reg);
|
||
int indx = expr->bitmap_index;
|
||
rtx set = single_set (insn);
|
||
rtx new_insn;
|
||
|
||
if (!set)
|
||
abort ();
|
||
new_insn = emit_insn_after (gen_rtx_SET (VOIDmode, reg, SET_DEST (set)),
|
||
insn);
|
||
/* Keep block number table up to date. */
|
||
set_block_num (new_insn, BLOCK_NUM (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, copying 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 ()
|
||
{
|
||
int i;
|
||
|
||
/* 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++)
|
||
{
|
||
struct expr *expr;
|
||
|
||
for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash)
|
||
{
|
||
struct occr *occr;
|
||
|
||
/* 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;
|
||
|
||
for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
|
||
{
|
||
struct occr *avail;
|
||
|
||
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, INSN_CUID (insn)))
|
||
continue;
|
||
/* Or if the expression doesn't reach the deleted one. */
|
||
if (! pre_expr_reaches_here_p (avail, expr,
|
||
BLOCK_NUM (occr->insn),
|
||
NULL))
|
||
continue;
|
||
|
||
/* Copy the result of avail to reaching_reg. */
|
||
pre_insert_copy_insn (expr, insn);
|
||
avail->copied_p = 1;
|
||
}
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Delete redundant computations.
|
||
These are ones that satisy ANTLOC & PPIN.
|
||
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 non-zero if a change is made. */
|
||
|
||
static int
|
||
pre_delete ()
|
||
{
|
||
int i, changed;
|
||
|
||
changed = 0;
|
||
for (i = 0; i < expr_hash_table_size; i++)
|
||
{
|
||
struct expr *expr;
|
||
|
||
for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash)
|
||
{
|
||
struct occr *occr;
|
||
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;
|
||
int bb = BLOCK_NUM (insn);
|
||
sbitmap ppin = pre_ppin[bb];
|
||
|
||
if (TEST_BIT (ppin, indx))
|
||
{
|
||
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)));
|
||
|
||
/* In theory this should never fail since we're creating
|
||
a reg->reg copy.
|
||
|
||
However, on the x86 some of the movXX patterns actually
|
||
contain clobbers of scratch regs. This may cause the
|
||
insn created by validate_change to not patch any pattern
|
||
and thus cause validate_change to fail. */
|
||
if (validate_change (insn, &SET_SRC (set),
|
||
expr->reaching_reg, 0))
|
||
{
|
||
occr->deleted_p = 1;
|
||
SET_BIT (pre_redundant, INSN_CUID (insn));
|
||
changed = 1;
|
||
gcse_subst_count++;
|
||
}
|
||
|
||
if (gcse_file)
|
||
{
|
||
fprintf (gcse_file, "PRE: redundant insn %d (expression %d) in bb %d, reaching reg is %d\n",
|
||
INSN_UID (insn), indx, bb, 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 and Fred Chow's thesis.
|
||
|
||
The M-R paper uses "TRANSP" to describe an expression as being transparent
|
||
in a block where as Chow's thesis uses "ALTERED". We use TRANSP.
|
||
|
||
??? 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 ()
|
||
{
|
||
int i;
|
||
int changed;
|
||
struct expr **index_map;
|
||
|
||
/* Compute a mapping from expression number (`bitmap_index') to
|
||
hash table entry. */
|
||
|
||
index_map = (struct expr **) alloca (n_exprs * sizeof (struct expr *));
|
||
bzero ((char *) index_map, n_exprs * sizeof (struct expr *));
|
||
for (i = 0; i < expr_hash_table_size; i++)
|
||
{
|
||
struct expr *expr;
|
||
|
||
for (expr = expr_hash_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 = sbitmap_alloc (max_cuid);
|
||
sbitmap_zero (pre_redundant);
|
||
|
||
/* 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 ();
|
||
|
||
/* Insert insns in places that make partially redundant expressions
|
||
fully redundant. */
|
||
pre_insert (index_map);
|
||
|
||
/* In other places with reaching expressions, copy the expression to the
|
||
specially allocated pseudo-reg that reaches the redundant expression. */
|
||
pre_insert_copies ();
|
||
|
||
free (pre_redundant);
|
||
|
||
return changed;
|
||
}
|
||
|
||
/* Top level routine to perform one PRE GCSE pass.
|
||
|
||
Return non-zero if a change was made. */
|
||
|
||
static int
|
||
one_pre_gcse_pass (f, pass)
|
||
rtx f;
|
||
int pass;
|
||
{
|
||
int changed = 0;
|
||
|
||
gcse_subst_count = 0;
|
||
gcse_create_count = 0;
|
||
|
||
alloc_expr_hash_table (max_cuid);
|
||
compute_expr_hash_table (f);
|
||
if (gcse_file)
|
||
dump_hash_table (gcse_file, "Expression", expr_hash_table,
|
||
expr_hash_table_size, n_exprs);
|
||
if (n_exprs > 0)
|
||
{
|
||
alloc_pre_mem (n_basic_blocks, n_exprs);
|
||
compute_pre_data ();
|
||
changed |= pre_gcse ();
|
||
free_pre_mem ();
|
||
}
|
||
free_expr_hash_table ();
|
||
|
||
if (gcse_file)
|
||
{
|
||
fprintf (gcse_file, "\n");
|
||
fprintf (gcse_file, "PRE GCSE of %s, pass %d: %d bytes needed, %d substs, %d insns created\n",
|
||
current_function_name, pass,
|
||
bytes_used, gcse_subst_count, gcse_create_count);
|
||
}
|
||
|
||
return changed;
|
||
}
|
||
|
||
/* If X contains any LABEL_REF's, add REG_LABEL notes for them to INSN.
|
||
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 (x, insn)
|
||
rtx x;
|
||
rtx insn;
|
||
{
|
||
enum rtx_code code = GET_CODE (x);
|
||
int i, j;
|
||
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 (slighly) 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_EXPR_LIST (REG_LABEL, XEXP (x, 0),
|
||
REG_NOTES (insn));
|
||
return;
|
||
}
|
||
|
||
fmt = GET_RTX_FORMAT (code);
|
||
for (i = GET_RTX_LENGTH (code) - 1; 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);
|
||
}
|
||
}
|