883 lines
25 KiB
C
883 lines
25 KiB
C
/* Control flow graph building code for GNU compiler.
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Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
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1999, 2000, 2001 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 2, or (at your option) any later
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING. If not, write to the Free
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Software Foundation, 59 Temple Place - Suite 330, Boston, MA
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02111-1307, USA. */
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/* find_basic_blocks divides the current function's rtl into basic
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blocks and constructs the CFG. The blocks are recorded in the
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basic_block_info array; the CFG exists in the edge structures
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referenced by the blocks.
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find_basic_blocks also finds any unreachable loops and deletes them.
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Available functionality:
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- CFG construction
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find_basic_blocks
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- Local CFG construction
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find_sub_basic_blocks */
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#include "config.h"
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#include "system.h"
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#include "tree.h"
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#include "rtl.h"
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#include "hard-reg-set.h"
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#include "basic-block.h"
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#include "regs.h"
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#include "flags.h"
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#include "output.h"
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#include "function.h"
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#include "except.h"
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#include "toplev.h"
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#include "timevar.h"
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#include "obstack.h"
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static int count_basic_blocks PARAMS ((rtx));
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static void find_basic_blocks_1 PARAMS ((rtx));
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static rtx find_label_refs PARAMS ((rtx, rtx));
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static void make_edges PARAMS ((rtx, int, int, int));
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static void make_label_edge PARAMS ((sbitmap *, basic_block,
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rtx, int));
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static void make_eh_edge PARAMS ((sbitmap *, basic_block, rtx));
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static void find_bb_boundaries PARAMS ((basic_block));
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static void compute_outgoing_frequencies PARAMS ((basic_block));
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static bool inside_basic_block_p PARAMS ((rtx));
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static bool control_flow_insn_p PARAMS ((rtx));
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/* Return true if insn is something that should be contained inside basic
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block. */
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static bool
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inside_basic_block_p (insn)
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rtx insn;
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{
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switch (GET_CODE (insn))
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{
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case CODE_LABEL:
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/* Avoid creating of basic block for jumptables. */
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return (NEXT_INSN (insn) == 0
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|| GET_CODE (NEXT_INSN (insn)) != JUMP_INSN
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|| (GET_CODE (PATTERN (NEXT_INSN (insn))) != ADDR_VEC
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&& GET_CODE (PATTERN (NEXT_INSN (insn))) != ADDR_DIFF_VEC));
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case JUMP_INSN:
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return (GET_CODE (PATTERN (insn)) != ADDR_VEC
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&& GET_CODE (PATTERN (insn)) != ADDR_DIFF_VEC);
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case CALL_INSN:
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case INSN:
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return true;
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case BARRIER:
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case NOTE:
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return false;
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default:
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abort ();
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}
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}
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/* Return true if INSN may cause control flow transfer, so it should be last in
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the basic block. */
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static bool
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control_flow_insn_p (insn)
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rtx insn;
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{
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rtx note;
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switch (GET_CODE (insn))
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{
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case NOTE:
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case CODE_LABEL:
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return false;
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case JUMP_INSN:
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/* Jump insn always causes control transfer except for tablejumps. */
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return (GET_CODE (PATTERN (insn)) != ADDR_VEC
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&& GET_CODE (PATTERN (insn)) != ADDR_DIFF_VEC);
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case CALL_INSN:
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/* Call insn may return to the nonlocal goto handler. */
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return ((nonlocal_goto_handler_labels
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&& (0 == (note = find_reg_note (insn, REG_EH_REGION,
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NULL_RTX))
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|| INTVAL (XEXP (note, 0)) >= 0))
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/* Or may trap. */
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|| can_throw_internal (insn));
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case INSN:
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return (flag_non_call_exceptions && can_throw_internal (insn));
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case BARRIER:
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/* It is nonsence to reach barrier when looking for the
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end of basic block, but before dead code is eliminated
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this may happen. */
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return false;
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default:
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abort ();
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}
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}
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/* Count the basic blocks of the function. */
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static int
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count_basic_blocks (f)
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rtx f;
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{
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int count = 0;
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bool saw_insn = false;
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rtx insn;
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for (insn = f; insn; insn = NEXT_INSN (insn))
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{
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/* Code labels and barriers causes curent basic block to be
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terminated at previous real insn. */
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if ((GET_CODE (insn) == CODE_LABEL || GET_CODE (insn) == BARRIER)
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&& saw_insn)
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count++, saw_insn = false;
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/* Start basic block if needed. */
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if (!saw_insn && inside_basic_block_p (insn))
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saw_insn = true;
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/* Control flow insn causes current basic block to be terminated. */
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if (saw_insn && control_flow_insn_p (insn))
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count++, saw_insn = false;
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}
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if (saw_insn)
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count++;
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/* The rest of the compiler works a bit smoother when we don't have to
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check for the edge case of do-nothing functions with no basic blocks. */
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if (count == 0)
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{
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emit_insn (gen_rtx_USE (VOIDmode, const0_rtx));
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count = 1;
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}
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return count;
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}
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/* Scan a list of insns for labels referred to other than by jumps.
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This is used to scan the alternatives of a call placeholder. */
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static rtx
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find_label_refs (f, lvl)
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rtx f;
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rtx lvl;
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{
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rtx insn;
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for (insn = f; insn; insn = NEXT_INSN (insn))
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if (INSN_P (insn) && GET_CODE (insn) != JUMP_INSN)
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{
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rtx note;
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/* Make a list of all labels referred to other than by jumps
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(which just don't have the REG_LABEL notes).
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Make a special exception for labels followed by an ADDR*VEC,
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as this would be a part of the tablejump setup code.
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Make a special exception to registers loaded with label
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values just before jump insns that use them. */
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for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
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if (REG_NOTE_KIND (note) == REG_LABEL)
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{
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rtx lab = XEXP (note, 0), next;
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if ((next = next_nonnote_insn (lab)) != NULL
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&& GET_CODE (next) == JUMP_INSN
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&& (GET_CODE (PATTERN (next)) == ADDR_VEC
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|| GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
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;
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else if (GET_CODE (lab) == NOTE)
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;
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else if (GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
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&& find_reg_note (NEXT_INSN (insn), REG_LABEL, lab))
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;
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else
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lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl);
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}
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}
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return lvl;
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}
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/* Create an edge between two basic blocks. FLAGS are auxiliary information
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about the edge that is accumulated between calls. */
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/* Create an edge from a basic block to a label. */
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static void
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make_label_edge (edge_cache, src, label, flags)
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sbitmap *edge_cache;
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basic_block src;
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rtx label;
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int flags;
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{
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if (GET_CODE (label) != CODE_LABEL)
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abort ();
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/* If the label was never emitted, this insn is junk, but avoid a
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crash trying to refer to BLOCK_FOR_INSN (label). This can happen
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as a result of a syntax error and a diagnostic has already been
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printed. */
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if (INSN_UID (label) == 0)
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return;
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cached_make_edge (edge_cache, src, BLOCK_FOR_INSN (label), flags);
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}
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/* Create the edges generated by INSN in REGION. */
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static void
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make_eh_edge (edge_cache, src, insn)
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sbitmap *edge_cache;
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basic_block src;
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rtx insn;
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{
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int is_call = GET_CODE (insn) == CALL_INSN ? EDGE_ABNORMAL_CALL : 0;
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rtx handlers, i;
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handlers = reachable_handlers (insn);
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for (i = handlers; i; i = XEXP (i, 1))
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make_label_edge (edge_cache, src, XEXP (i, 0),
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EDGE_ABNORMAL | EDGE_EH | is_call);
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free_INSN_LIST_list (&handlers);
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}
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/* Identify the edges between basic blocks MIN to MAX.
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NONLOCAL_LABEL_LIST is a list of non-local labels in the function. Blocks
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that are otherwise unreachable may be reachable with a non-local goto.
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BB_EH_END is an array indexed by basic block number in which we record
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the list of exception regions active at the end of the basic block. */
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static void
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make_edges (label_value_list, min, max, update_p)
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rtx label_value_list;
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int min, max, update_p;
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{
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int i;
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sbitmap *edge_cache = NULL;
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/* Assume no computed jump; revise as we create edges. */
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current_function_has_computed_jump = 0;
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/* Heavy use of computed goto in machine-generated code can lead to
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nearly fully-connected CFGs. In that case we spend a significant
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amount of time searching the edge lists for duplicates. */
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if (forced_labels || label_value_list)
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{
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edge_cache = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
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sbitmap_vector_zero (edge_cache, n_basic_blocks);
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if (update_p)
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for (i = min; i <= max; ++i)
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{
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edge e;
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for (e = BASIC_BLOCK (i)->succ; e ; e = e->succ_next)
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if (e->dest != EXIT_BLOCK_PTR)
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SET_BIT (edge_cache[i], e->dest->index);
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}
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}
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/* By nature of the way these get numbered, block 0 is always the entry. */
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if (min == 0)
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cached_make_edge (edge_cache, ENTRY_BLOCK_PTR, BASIC_BLOCK (0),
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EDGE_FALLTHRU);
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for (i = min; i <= max; ++i)
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{
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basic_block bb = BASIC_BLOCK (i);
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rtx insn, x;
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enum rtx_code code;
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int force_fallthru = 0;
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if (GET_CODE (bb->head) == CODE_LABEL && LABEL_ALTERNATE_NAME (bb->head))
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cached_make_edge (NULL, ENTRY_BLOCK_PTR, bb, 0);
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/* Examine the last instruction of the block, and discover the
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ways we can leave the block. */
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insn = bb->end;
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code = GET_CODE (insn);
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/* A branch. */
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if (code == JUMP_INSN)
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{
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rtx tmp;
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/* Recognize exception handling placeholders. */
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if (GET_CODE (PATTERN (insn)) == RESX)
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make_eh_edge (edge_cache, bb, insn);
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/* Recognize a non-local goto as a branch outside the
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current function. */
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else if (find_reg_note (insn, REG_NON_LOCAL_GOTO, NULL_RTX))
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;
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/* ??? Recognize a tablejump and do the right thing. */
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else if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
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&& (tmp = NEXT_INSN (tmp)) != NULL_RTX
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&& GET_CODE (tmp) == JUMP_INSN
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&& (GET_CODE (PATTERN (tmp)) == ADDR_VEC
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|| GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
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{
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rtvec vec;
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int j;
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if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
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vec = XVEC (PATTERN (tmp), 0);
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else
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vec = XVEC (PATTERN (tmp), 1);
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for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
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make_label_edge (edge_cache, bb,
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XEXP (RTVEC_ELT (vec, j), 0), 0);
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/* Some targets (eg, ARM) emit a conditional jump that also
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contains the out-of-range target. Scan for these and
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add an edge if necessary. */
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if ((tmp = single_set (insn)) != NULL
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&& SET_DEST (tmp) == pc_rtx
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&& GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
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&& GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF)
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make_label_edge (edge_cache, bb,
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XEXP (XEXP (SET_SRC (tmp), 2), 0), 0);
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#ifdef CASE_DROPS_THROUGH
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/* Silly VAXen. The ADDR_VEC is going to be in the way of
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us naturally detecting fallthru into the next block. */
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force_fallthru = 1;
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#endif
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}
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/* If this is a computed jump, then mark it as reaching
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everything on the label_value_list and forced_labels list. */
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else if (computed_jump_p (insn))
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{
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current_function_has_computed_jump = 1;
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for (x = label_value_list; x; x = XEXP (x, 1))
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make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL);
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for (x = forced_labels; x; x = XEXP (x, 1))
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make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL);
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}
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/* Returns create an exit out. */
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else if (returnjump_p (insn))
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cached_make_edge (edge_cache, bb, EXIT_BLOCK_PTR, 0);
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/* Otherwise, we have a plain conditional or unconditional jump. */
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else
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{
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if (! JUMP_LABEL (insn))
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abort ();
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make_label_edge (edge_cache, bb, JUMP_LABEL (insn), 0);
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}
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}
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/* If this is a sibling call insn, then this is in effect a combined call
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and return, and so we need an edge to the exit block. No need to
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worry about EH edges, since we wouldn't have created the sibling call
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in the first place. */
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if (code == CALL_INSN && SIBLING_CALL_P (insn))
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cached_make_edge (edge_cache, bb, EXIT_BLOCK_PTR,
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EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
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/* If this is a CALL_INSN, then mark it as reaching the active EH
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handler for this CALL_INSN. If we're handling non-call
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exceptions then any insn can reach any of the active handlers.
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Also mark the CALL_INSN as reaching any nonlocal goto handler. */
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else if (code == CALL_INSN || flag_non_call_exceptions)
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{
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/* Add any appropriate EH edges. */
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make_eh_edge (edge_cache, bb, insn);
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if (code == CALL_INSN && nonlocal_goto_handler_labels)
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{
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/* ??? This could be made smarter: in some cases it's possible
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to tell that certain calls will not do a nonlocal goto.
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For example, if the nested functions that do the nonlocal
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gotos do not have their addresses taken, then only calls to
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those functions or to other nested functions that use them
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could possibly do nonlocal gotos. */
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/* We do know that a REG_EH_REGION note with a value less
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than 0 is guaranteed not to perform a non-local goto. */
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rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
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if (!note || INTVAL (XEXP (note, 0)) >= 0)
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for (x = nonlocal_goto_handler_labels; x; x = XEXP (x, 1))
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make_label_edge (edge_cache, bb, XEXP (x, 0),
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EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
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}
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}
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/* Find out if we can drop through to the next block. */
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insn = next_nonnote_insn (insn);
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if (!insn || (i + 1 == n_basic_blocks && force_fallthru))
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cached_make_edge (edge_cache, bb, EXIT_BLOCK_PTR, EDGE_FALLTHRU);
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else if (i + 1 < n_basic_blocks)
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{
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rtx tmp = BLOCK_HEAD (i + 1);
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if (GET_CODE (tmp) == NOTE)
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tmp = next_nonnote_insn (tmp);
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if (force_fallthru || insn == tmp)
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cached_make_edge (edge_cache, bb, BASIC_BLOCK (i + 1),
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EDGE_FALLTHRU);
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}
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}
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if (edge_cache)
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sbitmap_vector_free (edge_cache);
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}
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/* Find all basic blocks of the function whose first insn is F.
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Collect and return a list of labels whose addresses are taken. This
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will be used in make_edges for use with computed gotos. */
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static void
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find_basic_blocks_1 (f)
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rtx f;
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{
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rtx insn, next;
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int i = 0;
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rtx bb_note = NULL_RTX;
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rtx lvl = NULL_RTX;
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rtx trll = NULL_RTX;
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rtx head = NULL_RTX;
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rtx end = NULL_RTX;
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/* We process the instructions in a slightly different way than we did
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previously. This is so that we see a NOTE_BASIC_BLOCK after we have
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closed out the previous block, so that it gets attached at the proper
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place. Since this form should be equivalent to the previous,
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count_basic_blocks continues to use the old form as a check. */
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for (insn = f; insn; insn = next)
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{
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enum rtx_code code = GET_CODE (insn);
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next = NEXT_INSN (insn);
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if ((GET_CODE (insn) == CODE_LABEL || GET_CODE (insn) == BARRIER)
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&& head)
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{
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create_basic_block_structure (i++, head, end, bb_note);
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head = end = NULL_RTX;
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bb_note = NULL_RTX;
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}
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if (inside_basic_block_p (insn))
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{
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if (head == NULL_RTX)
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head = insn;
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end = insn;
|
||
}
|
||
|
||
if (head && control_flow_insn_p (insn))
|
||
{
|
||
create_basic_block_structure (i++, head, end, bb_note);
|
||
head = end = NULL_RTX;
|
||
bb_note = NULL_RTX;
|
||
}
|
||
|
||
switch (code)
|
||
{
|
||
case NOTE:
|
||
{
|
||
int kind = NOTE_LINE_NUMBER (insn);
|
||
|
||
/* Look for basic block notes with which to keep the
|
||
basic_block_info pointers stable. Unthread the note now;
|
||
we'll put it back at the right place in create_basic_block.
|
||
Or not at all if we've already found a note in this block. */
|
||
if (kind == NOTE_INSN_BASIC_BLOCK)
|
||
{
|
||
if (bb_note == NULL_RTX)
|
||
bb_note = insn;
|
||
else
|
||
next = delete_insn (insn);
|
||
}
|
||
break;
|
||
}
|
||
|
||
case CODE_LABEL:
|
||
case JUMP_INSN:
|
||
case INSN:
|
||
case BARRIER:
|
||
break;
|
||
|
||
case CALL_INSN:
|
||
if (GET_CODE (PATTERN (insn)) == CALL_PLACEHOLDER)
|
||
{
|
||
/* Scan each of the alternatives for label refs. */
|
||
lvl = find_label_refs (XEXP (PATTERN (insn), 0), lvl);
|
||
lvl = find_label_refs (XEXP (PATTERN (insn), 1), lvl);
|
||
lvl = find_label_refs (XEXP (PATTERN (insn), 2), lvl);
|
||
/* Record its tail recursion label, if any. */
|
||
if (XEXP (PATTERN (insn), 3) != NULL_RTX)
|
||
trll = alloc_EXPR_LIST (0, XEXP (PATTERN (insn), 3), trll);
|
||
}
|
||
break;
|
||
|
||
default:
|
||
abort ();
|
||
}
|
||
|
||
if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
|
||
{
|
||
rtx note;
|
||
|
||
/* Make a list of all labels referred to other than by jumps.
|
||
|
||
Make a special exception for labels followed by an ADDR*VEC,
|
||
as this would be a part of the tablejump setup code.
|
||
|
||
Make a special exception to registers loaded with label
|
||
values just before jump insns that use them. */
|
||
|
||
for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
|
||
if (REG_NOTE_KIND (note) == REG_LABEL)
|
||
{
|
||
rtx lab = XEXP (note, 0), next;
|
||
|
||
if ((next = next_nonnote_insn (lab)) != NULL
|
||
&& GET_CODE (next) == JUMP_INSN
|
||
&& (GET_CODE (PATTERN (next)) == ADDR_VEC
|
||
|| GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
|
||
;
|
||
else if (GET_CODE (lab) == NOTE)
|
||
;
|
||
else if (GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
|
||
&& find_reg_note (NEXT_INSN (insn), REG_LABEL, lab))
|
||
;
|
||
else
|
||
lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl);
|
||
}
|
||
}
|
||
}
|
||
|
||
if (head != NULL_RTX)
|
||
create_basic_block_structure (i++, head, end, bb_note);
|
||
else if (bb_note)
|
||
delete_insn (bb_note);
|
||
|
||
if (i != n_basic_blocks)
|
||
abort ();
|
||
|
||
label_value_list = lvl;
|
||
tail_recursion_label_list = trll;
|
||
}
|
||
|
||
|
||
/* Find basic blocks of the current function.
|
||
F is the first insn of the function and NREGS the number of register
|
||
numbers in use. */
|
||
|
||
void
|
||
find_basic_blocks (f, nregs, file)
|
||
rtx f;
|
||
int nregs ATTRIBUTE_UNUSED;
|
||
FILE *file ATTRIBUTE_UNUSED;
|
||
{
|
||
int max_uid;
|
||
timevar_push (TV_CFG);
|
||
|
||
basic_block_for_insn = 0;
|
||
|
||
/* Flush out existing data. */
|
||
if (basic_block_info != NULL)
|
||
{
|
||
int i;
|
||
|
||
clear_edges ();
|
||
|
||
/* Clear bb->aux on all extant basic blocks. We'll use this as a
|
||
tag for reuse during create_basic_block, just in case some pass
|
||
copies around basic block notes improperly. */
|
||
for (i = 0; i < n_basic_blocks; ++i)
|
||
BASIC_BLOCK (i)->aux = NULL;
|
||
|
||
VARRAY_FREE (basic_block_info);
|
||
}
|
||
|
||
n_basic_blocks = count_basic_blocks (f);
|
||
|
||
/* Size the basic block table. The actual structures will be allocated
|
||
by find_basic_blocks_1, since we want to keep the structure pointers
|
||
stable across calls to find_basic_blocks. */
|
||
/* ??? This whole issue would be much simpler if we called find_basic_blocks
|
||
exactly once, and thereafter we don't have a single long chain of
|
||
instructions at all until close to the end of compilation when we
|
||
actually lay them out. */
|
||
|
||
VARRAY_BB_INIT (basic_block_info, n_basic_blocks, "basic_block_info");
|
||
|
||
find_basic_blocks_1 (f);
|
||
|
||
/* Record the block to which an insn belongs. */
|
||
/* ??? This should be done another way, by which (perhaps) a label is
|
||
tagged directly with the basic block that it starts. It is used for
|
||
more than that currently, but IMO that is the only valid use. */
|
||
|
||
max_uid = get_max_uid ();
|
||
#ifdef AUTO_INC_DEC
|
||
/* Leave space for insns life_analysis makes in some cases for auto-inc.
|
||
These cases are rare, so we don't need too much space. */
|
||
max_uid += max_uid / 10;
|
||
#endif
|
||
|
||
compute_bb_for_insn (max_uid);
|
||
|
||
/* Discover the edges of our cfg. */
|
||
make_edges (label_value_list, 0, n_basic_blocks - 1, 0);
|
||
|
||
/* Do very simple cleanup now, for the benefit of code that runs between
|
||
here and cleanup_cfg, e.g. thread_prologue_and_epilogue_insns. */
|
||
tidy_fallthru_edges ();
|
||
|
||
#ifdef ENABLE_CHECKING
|
||
verify_flow_info ();
|
||
#endif
|
||
timevar_pop (TV_CFG);
|
||
}
|
||
|
||
/* State of basic block as seen by find_sub_basic_blocks. */
|
||
enum state {BLOCK_NEW = 0, BLOCK_ORIGINAL, BLOCK_TO_SPLIT};
|
||
|
||
#define STATE(BB) (enum state) ((size_t) (BB)->aux)
|
||
#define SET_STATE(BB, STATE) ((BB)->aux = (void *) (size_t) (STATE))
|
||
|
||
/* Scan basic block BB for possible BB boundaries inside the block
|
||
and create new basic blocks in the progress. */
|
||
|
||
static void
|
||
find_bb_boundaries (bb)
|
||
basic_block bb;
|
||
{
|
||
rtx insn = bb->head;
|
||
rtx end = bb->end;
|
||
rtx flow_transfer_insn = NULL_RTX;
|
||
edge fallthru = NULL;
|
||
|
||
if (insn == bb->end)
|
||
return;
|
||
|
||
if (GET_CODE (insn) == CODE_LABEL)
|
||
insn = NEXT_INSN (insn);
|
||
|
||
/* Scan insn chain and try to find new basic block boundaries. */
|
||
while (1)
|
||
{
|
||
enum rtx_code code = GET_CODE (insn);
|
||
|
||
/* On code label, split current basic block. */
|
||
if (code == CODE_LABEL)
|
||
{
|
||
fallthru = split_block (bb, PREV_INSN (insn));
|
||
if (flow_transfer_insn)
|
||
bb->end = flow_transfer_insn;
|
||
|
||
bb = fallthru->dest;
|
||
remove_edge (fallthru);
|
||
flow_transfer_insn = NULL_RTX;
|
||
if (LABEL_ALTERNATE_NAME (insn))
|
||
make_edge (ENTRY_BLOCK_PTR, bb, 0);
|
||
}
|
||
|
||
/* In case we've previously seen an insn that effects a control
|
||
flow transfer, split the block. */
|
||
if (flow_transfer_insn && inside_basic_block_p (insn))
|
||
{
|
||
fallthru = split_block (bb, PREV_INSN (insn));
|
||
bb->end = flow_transfer_insn;
|
||
bb = fallthru->dest;
|
||
remove_edge (fallthru);
|
||
flow_transfer_insn = NULL_RTX;
|
||
}
|
||
|
||
if (control_flow_insn_p (insn))
|
||
flow_transfer_insn = insn;
|
||
if (insn == end)
|
||
break;
|
||
insn = NEXT_INSN (insn);
|
||
}
|
||
|
||
/* In case expander replaced normal insn by sequence terminating by
|
||
return and barrier, or possibly other sequence not behaving like
|
||
ordinary jump, we need to take care and move basic block boundary. */
|
||
if (flow_transfer_insn)
|
||
bb->end = flow_transfer_insn;
|
||
|
||
/* We've possibly replaced the conditional jump by conditional jump
|
||
followed by cleanup at fallthru edge, so the outgoing edges may
|
||
be dead. */
|
||
purge_dead_edges (bb);
|
||
}
|
||
|
||
/* Assume that frequency of basic block B is known. Compute frequencies
|
||
and probabilities of outgoing edges. */
|
||
|
||
static void
|
||
compute_outgoing_frequencies (b)
|
||
basic_block b;
|
||
{
|
||
edge e, f;
|
||
|
||
if (b->succ && b->succ->succ_next && !b->succ->succ_next->succ_next)
|
||
{
|
||
rtx note = find_reg_note (b->end, REG_BR_PROB, NULL);
|
||
int probability;
|
||
|
||
if (!note)
|
||
return;
|
||
|
||
probability = INTVAL (XEXP (find_reg_note (b->end,
|
||
REG_BR_PROB, NULL),
|
||
0));
|
||
e = BRANCH_EDGE (b);
|
||
e->probability = probability;
|
||
e->count = ((b->count * probability + REG_BR_PROB_BASE / 2)
|
||
/ REG_BR_PROB_BASE);
|
||
f = FALLTHRU_EDGE (b);
|
||
f->probability = REG_BR_PROB_BASE - probability;
|
||
f->count = b->count - e->count;
|
||
}
|
||
|
||
if (b->succ && !b->succ->succ_next)
|
||
{
|
||
e = b->succ;
|
||
e->probability = REG_BR_PROB_BASE;
|
||
e->count = b->count;
|
||
}
|
||
}
|
||
|
||
/* Assume that someone emitted code with control flow instructions to the
|
||
basic block. Update the data structure. */
|
||
|
||
void
|
||
find_many_sub_basic_blocks (blocks)
|
||
sbitmap blocks;
|
||
{
|
||
int i;
|
||
int min, max;
|
||
|
||
for (i = 0; i < n_basic_blocks; i++)
|
||
SET_STATE (BASIC_BLOCK (i),
|
||
TEST_BIT (blocks, i) ? BLOCK_TO_SPLIT : BLOCK_ORIGINAL);
|
||
|
||
for (i = 0; i < n_basic_blocks; i++)
|
||
if (STATE (BASIC_BLOCK (i)) == BLOCK_TO_SPLIT)
|
||
find_bb_boundaries (BASIC_BLOCK (i));
|
||
|
||
for (i = 0; i < n_basic_blocks; i++)
|
||
if (STATE (BASIC_BLOCK (i)) != BLOCK_ORIGINAL)
|
||
break;
|
||
|
||
min = max = i;
|
||
for (; i < n_basic_blocks; i++)
|
||
if (STATE (BASIC_BLOCK (i)) != BLOCK_ORIGINAL)
|
||
max = i;
|
||
|
||
/* Now re-scan and wire in all edges. This expect simple (conditional)
|
||
jumps at the end of each new basic blocks. */
|
||
make_edges (NULL, min, max, 1);
|
||
|
||
/* Update branch probabilities. Expect only (un)conditional jumps
|
||
to be created with only the forward edges. */
|
||
for (i = min; i <= max; i++)
|
||
{
|
||
edge e;
|
||
basic_block b = BASIC_BLOCK (i);
|
||
|
||
if (STATE (b) == BLOCK_ORIGINAL)
|
||
continue;
|
||
if (STATE (b) == BLOCK_NEW)
|
||
{
|
||
b->count = 0;
|
||
b->frequency = 0;
|
||
for (e = b->pred; e; e=e->pred_next)
|
||
{
|
||
b->count += e->count;
|
||
b->frequency += EDGE_FREQUENCY (e);
|
||
}
|
||
}
|
||
|
||
compute_outgoing_frequencies (b);
|
||
}
|
||
|
||
for (i = 0; i < n_basic_blocks; i++)
|
||
SET_STATE (BASIC_BLOCK (i), 0);
|
||
}
|
||
|
||
/* Like above but for single basic block only. */
|
||
|
||
void
|
||
find_sub_basic_blocks (bb)
|
||
basic_block bb;
|
||
{
|
||
int i;
|
||
int min, max;
|
||
basic_block next = (bb->index == n_basic_blocks - 1
|
||
? NULL : BASIC_BLOCK (bb->index + 1));
|
||
|
||
min = bb->index;
|
||
find_bb_boundaries (bb);
|
||
max = (next ? next->index : n_basic_blocks) - 1;
|
||
|
||
/* Now re-scan and wire in all edges. This expect simple (conditional)
|
||
jumps at the end of each new basic blocks. */
|
||
make_edges (NULL, min, max, 1);
|
||
|
||
/* Update branch probabilities. Expect only (un)conditional jumps
|
||
to be created with only the forward edges. */
|
||
for (i = min; i <= max; i++)
|
||
{
|
||
edge e;
|
||
basic_block b = BASIC_BLOCK (i);
|
||
|
||
if (i != min)
|
||
{
|
||
b->count = 0;
|
||
b->frequency = 0;
|
||
for (e = b->pred; e; e=e->pred_next)
|
||
{
|
||
b->count += e->count;
|
||
b->frequency += EDGE_FREQUENCY (e);
|
||
}
|
||
}
|
||
|
||
compute_outgoing_frequencies (b);
|
||
}
|
||
}
|