cse.c (is_dead_reg): Change into inline function that is not called through for_each_rtx.
* cse.c (is_dead_reg): Change into inline function that is not called through for_each_rtx. (set_live_p): Adjust caller. (insn_live_p): Don't reset DEBUG_INSNs here. (struct dead_debug_insn_data): New data. (count_stores, is_dead_debug_insn, replace_dead_reg): New functions. (delete_trivially_dead_insns): If there is just one setter for the dead reg that is referenced by some DEBUG_INSNs, create a DEBUG_EXPR and add DEBUG_INSN for it right before the removed setter and use the DEBUG_EXPR instead of the dead pseudo. From-SVN: r165452
This commit is contained in:
Jakub Jelinek
Jakub Jelinek
parent
d2e60b7bc2
commit
6699b754e1
2 changed files with 180 additions and 25 deletions
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@ -1,4 +1,18 @@
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2010-10-14 Jakub Jelinek <jakub@redhat.com>
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* cse.c (is_dead_reg): Change into inline function that is not
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called through for_each_rtx.
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(set_live_p): Adjust caller.
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(insn_live_p): Don't reset DEBUG_INSNs here.
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(struct dead_debug_insn_data): New data.
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(count_stores, is_dead_debug_insn, replace_dead_reg): New functions.
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(delete_trivially_dead_insns): If there is just one setter for the
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dead reg that is referenced by some DEBUG_INSNs, create a DEBUG_EXPR
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and add DEBUG_INSN for it right before the removed setter and
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use the DEBUG_EXPR instead of the dead pseudo.
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2010-10-14 Zdenek Dvorak <rakdver@kam.uniff.cz>
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* et-forest.c (et_nca): Return NULL immediately when
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the dominance forest has disjoint components.
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191
gcc/cse.c
191
gcc/cse.c
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@ -1,6 +1,6 @@
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/* Common subexpression elimination for GNU compiler.
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Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998
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1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
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1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
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Free Software Foundation, Inc.
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This file is part of GCC.
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@ -6698,14 +6698,11 @@ count_reg_usage (rtx x, int *counts, rtx dest, int incr)
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}
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}
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/* Return true if a register is dead. Can be used in for_each_rtx. */
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/* Return true if X is a dead register. */
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static int
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is_dead_reg (rtx *loc, void *data)
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static inline int
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is_dead_reg (rtx x, int *counts)
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{
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rtx x = *loc;
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int *counts = (int *)data;
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return (REG_P (x)
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&& REGNO (x) >= FIRST_PSEUDO_REGISTER
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&& counts[REGNO (x)] == 0);
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@ -6731,7 +6728,7 @@ set_live_p (rtx set, rtx insn ATTRIBUTE_UNUSED, /* Only used with HAVE_cc0. */
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|| !reg_referenced_p (cc0_rtx, PATTERN (tem))))
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return false;
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#endif
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else if (!is_dead_reg (&SET_DEST (set), counts)
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else if (!is_dead_reg (SET_DEST (set), counts)
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|| side_effects_p (SET_SRC (set)))
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return true;
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return false;
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@ -6775,21 +6772,68 @@ insn_live_p (rtx insn, int *counts)
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else if (INSN_VAR_LOCATION_DECL (insn) == INSN_VAR_LOCATION_DECL (next))
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return false;
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/* If this debug insn references a dead register, drop the
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location expression for now. ??? We could try to find the
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def and see if propagation is possible. */
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if (for_each_rtx (&INSN_VAR_LOCATION_LOC (insn), is_dead_reg, counts))
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{
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INSN_VAR_LOCATION_LOC (insn) = gen_rtx_UNKNOWN_VAR_LOC ();
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df_insn_rescan (insn);
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}
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return true;
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}
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else
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return true;
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}
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/* Count the number of stores into pseudo. Callback for note_stores. */
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static void
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count_stores (rtx x, const_rtx set ATTRIBUTE_UNUSED, void *data)
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{
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int *counts = (int *) data;
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if (REG_P (x) && REGNO (x) >= FIRST_PSEUDO_REGISTER)
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counts[REGNO (x)]++;
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}
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struct dead_debug_insn_data
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{
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int *counts;
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rtx *replacements;
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bool seen_repl;
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};
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/* Return if a DEBUG_INSN needs to be reset because some dead
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pseudo doesn't have a replacement. Callback for for_each_rtx. */
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static int
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is_dead_debug_insn (rtx *loc, void *data)
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{
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rtx x = *loc;
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struct dead_debug_insn_data *ddid = (struct dead_debug_insn_data *) data;
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if (is_dead_reg (x, ddid->counts))
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{
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if (ddid->replacements && ddid->replacements[REGNO (x)] != NULL_RTX)
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ddid->seen_repl = true;
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else
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return 1;
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}
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return 0;
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}
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/* Replace a dead pseudo in a DEBUG_INSN with replacement DEBUG_EXPR.
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Callback for simplify_replace_fn_rtx. */
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static rtx
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replace_dead_reg (rtx x, const_rtx old_rtx ATTRIBUTE_UNUSED, void *data)
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{
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rtx *replacements = (rtx *) data;
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if (REG_P (x)
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&& REGNO (x) >= FIRST_PSEUDO_REGISTER
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&& replacements[REGNO (x)] != NULL_RTX)
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{
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if (GET_MODE (x) == GET_MODE (replacements[REGNO (x)]))
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return replacements[REGNO (x)];
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return lowpart_subreg (GET_MODE (x), replacements[REGNO (x)],
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GET_MODE (replacements[REGNO (x)]));
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}
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return NULL_RTX;
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}
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/* Scan all the insns and delete any that are dead; i.e., they store a register
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that is never used or they copy a register to itself.
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@ -6803,22 +6847,51 @@ delete_trivially_dead_insns (rtx insns, int nreg)
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{
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int *counts;
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rtx insn, prev;
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rtx *replacements = NULL;
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int ndead = 0;
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timevar_push (TV_DELETE_TRIVIALLY_DEAD);
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/* First count the number of times each register is used. */
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counts = XCNEWVEC (int, nreg);
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for (insn = insns; insn; insn = NEXT_INSN (insn))
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if (INSN_P (insn))
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count_reg_usage (insn, counts, NULL_RTX, 1);
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if (MAY_HAVE_DEBUG_INSNS)
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{
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counts = XCNEWVEC (int, nreg * 3);
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for (insn = insns; insn; insn = NEXT_INSN (insn))
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if (DEBUG_INSN_P (insn))
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count_reg_usage (INSN_VAR_LOCATION_LOC (insn), counts + nreg,
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NULL_RTX, 1);
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else if (INSN_P (insn))
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{
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count_reg_usage (insn, counts, NULL_RTX, 1);
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note_stores (PATTERN (insn), count_stores, counts + nreg * 2);
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}
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/* If there can be debug insns, COUNTS are 3 consecutive arrays.
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First one counts how many times each pseudo is used outside
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of debug insns, second counts how many times each pseudo is
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used in debug insns and third counts how many times a pseudo
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is stored. */
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}
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else
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{
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counts = XCNEWVEC (int, nreg);
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for (insn = insns; insn; insn = NEXT_INSN (insn))
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if (INSN_P (insn))
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count_reg_usage (insn, counts, NULL_RTX, 1);
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/* If no debug insns can be present, COUNTS is just an array
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which counts how many times each pseudo is used. */
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}
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/* Go from the last insn to the first and delete insns that only set unused
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registers or copy a register to itself. As we delete an insn, remove
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usage counts for registers it uses.
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The first jump optimization pass may leave a real insn as the last
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insn in the function. We must not skip that insn or we may end
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up deleting code that is not really dead. */
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up deleting code that is not really dead.
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If some otherwise unused register is only used in DEBUG_INSNs,
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try to create a DEBUG_EXPR temporary and emit a DEBUG_INSN before
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the setter. Then go through DEBUG_INSNs and if a DEBUG_EXPR
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has been created for the unused register, replace it with
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the DEBUG_EXPR, otherwise reset the DEBUG_INSN. */
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for (insn = get_last_insn (); insn; insn = prev)
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{
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int live_insn = 0;
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@ -6834,12 +6907,80 @@ delete_trivially_dead_insns (rtx insns, int nreg)
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if (! live_insn && dbg_cnt (delete_trivial_dead))
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{
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count_reg_usage (insn, counts, NULL_RTX, -1);
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if (DEBUG_INSN_P (insn))
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count_reg_usage (INSN_VAR_LOCATION_LOC (insn), counts + nreg,
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NULL_RTX, -1);
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else
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{
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rtx set;
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if (MAY_HAVE_DEBUG_INSNS
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&& (set = single_set (insn)) != NULL_RTX
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&& is_dead_reg (SET_DEST (set), counts)
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/* Used at least once in some DEBUG_INSN. */
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&& counts[REGNO (SET_DEST (set)) + nreg] > 0
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/* And set exactly once. */
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&& counts[REGNO (SET_DEST (set)) + nreg * 2] == 1
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&& !side_effects_p (SET_SRC (set))
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&& asm_noperands (PATTERN (insn)) < 0)
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{
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rtx dval, bind;
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/* Create DEBUG_EXPR (and DEBUG_EXPR_DECL). */
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dval = make_debug_expr_from_rtl (SET_DEST (set));
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/* Emit a debug bind insn before the insn in which
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reg dies. */
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bind = gen_rtx_VAR_LOCATION (GET_MODE (SET_DEST (set)),
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DEBUG_EXPR_TREE_DECL (dval),
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SET_SRC (set),
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VAR_INIT_STATUS_INITIALIZED);
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count_reg_usage (bind, counts + nreg, NULL_RTX, 1);
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bind = emit_debug_insn_before (bind, insn);
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df_insn_rescan (bind);
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if (replacements == NULL)
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replacements = XCNEWVEC (rtx, nreg);
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replacements[REGNO (SET_DEST (set))] = dval;
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}
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count_reg_usage (insn, counts, NULL_RTX, -1);
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ndead++;
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}
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delete_insn_and_edges (insn);
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ndead++;
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}
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}
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if (MAY_HAVE_DEBUG_INSNS)
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{
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struct dead_debug_insn_data ddid;
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ddid.counts = counts;
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ddid.replacements = replacements;
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for (insn = get_last_insn (); insn; insn = PREV_INSN (insn))
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if (DEBUG_INSN_P (insn))
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{
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/* If this debug insn references a dead register that wasn't replaced
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with an DEBUG_EXPR, reset the DEBUG_INSN. */
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ddid.seen_repl = false;
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if (for_each_rtx (&INSN_VAR_LOCATION_LOC (insn),
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is_dead_debug_insn, &ddid))
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{
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INSN_VAR_LOCATION_LOC (insn) = gen_rtx_UNKNOWN_VAR_LOC ();
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df_insn_rescan (insn);
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}
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else if (ddid.seen_repl)
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{
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INSN_VAR_LOCATION_LOC (insn)
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= simplify_replace_fn_rtx (INSN_VAR_LOCATION_LOC (insn),
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NULL_RTX, replace_dead_reg,
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replacements);
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df_insn_rescan (insn);
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}
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}
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if (replacements)
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free (replacements);
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}
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if (dump_file && ndead)
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fprintf (dump_file, "Deleted %i trivially dead insns\n",
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ndead);
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