/* Common subexpression elimination for GNU compiler.
Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998
- 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
+ 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
Free Software Foundation, Inc.
This file is part of GCC.
#include "regs.h"
#include "basic-block.h"
#include "flags.h"
-#include "real.h"
#include "insn-config.h"
#include "recog.h"
#include "function.h"
#include "expr.h"
+#include "diagnostic-core.h"
#include "toplev.h"
#include "output.h"
#include "ggc.h"
On all machines, we can't record any global registers.
Nor should we record any register that is in a small
- class, as defined by CLASS_LIKELY_SPILLED_P. */
+ class, as defined by TARGET_CLASS_LIKELY_SPILLED_P. */
bool record;
if (regno >= FIRST_PSEUDO_REGISTER)
record = true;
else if (targetm.small_register_classes_for_mode_p (GET_MODE (x)))
record = false;
- else if (CLASS_LIKELY_SPILLED_P (REGNO_REG_CLASS (regno)))
+ else if (targetm.class_likely_spilled_p (REGNO_REG_CLASS (regno)))
record = false;
else
record = true;
case MEM:
if (for_gcse)
{
+ /* Can't merge two expressions in different alias sets, since we
+ can decide that the expression is transparent in a block when
+ it isn't, due to it being set with the different alias set. */
+ if (MEM_ALIAS_SET (x) != MEM_ALIAS_SET (y))
+ return 0;
+
/* A volatile mem should not be considered equivalent to any
other. */
if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
return 0;
-
- /* Can't merge two expressions in different alias sets, since we
- can decide that the expression is transparent in a block when
- it isn't, due to it being set with the different alias set.
-
- Also, can't merge two expressions with different MEM_ATTRS.
- They could e.g. be two different entities allocated into the
- same space on the stack (see e.g. PR25130). In that case, the
- MEM addresses can be the same, even though the two MEMs are
- absolutely not equivalent.
-
- But because really all MEM attributes should be the same for
- equivalent MEMs, we just use the invariant that MEMs that have
- the same attributes share the same mem_attrs data structure. */
- if (MEM_ATTRS (x) != MEM_ATTRS (y))
- return 0;
}
break;
if (MEM_P (XEXP (x, 0)))
canon_reg (XEXP (x, 0), insn);
}
-
/* Canonicalize a USE of a pseudo register or memory location. */
else if (GET_CODE (x) == USE
&& ! (REG_P (XEXP (x, 0))
&& REGNO (XEXP (x, 0)) < FIRST_PSEUDO_REGISTER))
- canon_reg (XEXP (x, 0), insn);
+ canon_reg (x, insn);
+ else if (GET_CODE (x) == ASM_OPERANDS)
+ {
+ for (i = ASM_OPERANDS_INPUT_LENGTH (x) - 1; i >= 0; i--)
+ {
+ rtx input = ASM_OPERANDS_INPUT (x, i);
+ if (!(REG_P (input) && REGNO (input) < FIRST_PSEUDO_REGISTER))
+ {
+ input = canon_reg (input, insn);
+ validate_change (insn, &ASM_OPERANDS_INPUT (x, i), input, 1);
+ }
+ }
+ }
else if (GET_CODE (x) == CALL)
{
/* The result of apply_change_group can be ignored; see canon_reg. */
dest = canon_rtx (SET_DEST (sets[i].rtl));
if (!MEM_P (src) || !MEM_P (dest)
- || !nonoverlapping_memrefs_p (src, dest))
+ || !nonoverlapping_memrefs_p (src, dest, false))
break;
}
}
}
+ optimize_this_for_speed_p = optimize_bb_for_speed_p (bb);
FOR_BB_INSNS (bb, insn)
{
- optimize_this_for_speed_p = optimize_bb_for_speed_p (bb);
/* If we have processed 1,000 insns, flush the hash table to
avoid extreme quadratic behavior. We must not include NOTEs
in the count since there may be more of them when generating
recorded_label_ref = true;
#ifdef HAVE_cc0
- /* If the previous insn set CC0 and this insn no longer
- references CC0, delete the previous insn. Here we use
- fact that nothing expects CC0 to be valid over an insn,
- which is true until the final pass. */
- {
- rtx prev_insn, tem;
-
- prev_insn = PREV_INSN (insn);
- if (prev_insn && NONJUMP_INSN_P (prev_insn)
- && (tem = single_set (prev_insn)) != 0
- && SET_DEST (tem) == cc0_rtx
- && ! reg_mentioned_p (cc0_rtx, PATTERN (insn)))
- delete_insn (prev_insn);
- }
-
- /* If this insn is not the last insn in the basic block,
- it will be PREV_INSN(insn) in the next iteration. If
- we recorded any CC0-related information for this insn,
- remember it. */
- if (insn != BB_END (bb))
+ if (NONDEBUG_INSN_P (insn))
{
- prev_insn_cc0 = this_insn_cc0;
- prev_insn_cc0_mode = this_insn_cc0_mode;
+ /* If the previous insn sets CC0 and this insn no
+ longer references CC0, delete the previous insn.
+ Here we use fact that nothing expects CC0 to be
+ valid over an insn, which is true until the final
+ pass. */
+ rtx prev_insn, tem;
+
+ prev_insn = prev_nonnote_nondebug_insn (insn);
+ if (prev_insn && NONJUMP_INSN_P (prev_insn)
+ && (tem = single_set (prev_insn)) != NULL_RTX
+ && SET_DEST (tem) == cc0_rtx
+ && ! reg_mentioned_p (cc0_rtx, PATTERN (insn)))
+ delete_insn (prev_insn);
+
+ /* If this insn is not the last insn in the basic
+ block, it will be PREV_INSN(insn) in the next
+ iteration. If we recorded any CC0-related
+ information for this insn, remember it. */
+ if (insn != BB_END (bb))
+ {
+ prev_insn_cc0 = this_insn_cc0;
+ prev_insn_cc0_mode = this_insn_cc0_mode;
+ }
}
#endif
}
/* With non-call exceptions, we are not always able to update
the CFG properly inside cse_insn. So clean up possibly
redundant EH edges here. */
- if (flag_non_call_exceptions && have_eh_succ_edges (bb))
+ if (cfun->can_throw_non_call_exceptions && have_eh_succ_edges (bb))
cse_cfg_altered |= purge_dead_edges (bb);
/* If we changed a conditional jump, we may have terminated
}
}
\f
-/* Return true if a register is dead. Can be used in for_each_rtx. */
+/* Return true if X is a dead register. */
-static int
-is_dead_reg (rtx *loc, void *data)
+static inline int
+is_dead_reg (rtx x, int *counts)
{
- rtx x = *loc;
- int *counts = (int *)data;
-
return (REG_P (x)
&& REGNO (x) >= FIRST_PSEUDO_REGISTER
&& counts[REGNO (x)] == 0);
#ifdef HAVE_cc0
else if (GET_CODE (SET_DEST (set)) == CC0
&& !side_effects_p (SET_SRC (set))
- && ((tem = next_nonnote_insn (insn)) == 0
+ && ((tem = next_nonnote_nondebug_insn (insn)) == NULL_RTX
|| !INSN_P (tem)
|| !reg_referenced_p (cc0_rtx, PATTERN (tem))))
return false;
#endif
- else if (!is_dead_reg (&SET_DEST (set), counts)
+ else if (!is_dead_reg (SET_DEST (set), counts)
|| side_effects_p (SET_SRC (set)))
return true;
return false;
else if (INSN_VAR_LOCATION_DECL (insn) == INSN_VAR_LOCATION_DECL (next))
return false;
- /* If this debug insn references a dead register, drop the
- location expression for now. ??? We could try to find the
- def and see if propagation is possible. */
- if (for_each_rtx (&INSN_VAR_LOCATION_LOC (insn), is_dead_reg, counts))
- {
- INSN_VAR_LOCATION_LOC (insn) = gen_rtx_UNKNOWN_VAR_LOC ();
- df_insn_rescan (insn);
- }
-
return true;
}
else
return true;
}
+/* Count the number of stores into pseudo. Callback for note_stores. */
+
+static void
+count_stores (rtx x, const_rtx set ATTRIBUTE_UNUSED, void *data)
+{
+ int *counts = (int *) data;
+ if (REG_P (x) && REGNO (x) >= FIRST_PSEUDO_REGISTER)
+ counts[REGNO (x)]++;
+}
+
+struct dead_debug_insn_data
+{
+ int *counts;
+ rtx *replacements;
+ bool seen_repl;
+};
+
+/* Return if a DEBUG_INSN needs to be reset because some dead
+ pseudo doesn't have a replacement. Callback for for_each_rtx. */
+
+static int
+is_dead_debug_insn (rtx *loc, void *data)
+{
+ rtx x = *loc;
+ struct dead_debug_insn_data *ddid = (struct dead_debug_insn_data *) data;
+
+ if (is_dead_reg (x, ddid->counts))
+ {
+ if (ddid->replacements && ddid->replacements[REGNO (x)] != NULL_RTX)
+ ddid->seen_repl = true;
+ else
+ return 1;
+ }
+ return 0;
+}
+
+/* Replace a dead pseudo in a DEBUG_INSN with replacement DEBUG_EXPR.
+ Callback for simplify_replace_fn_rtx. */
+
+static rtx
+replace_dead_reg (rtx x, const_rtx old_rtx ATTRIBUTE_UNUSED, void *data)
+{
+ rtx *replacements = (rtx *) data;
+
+ if (REG_P (x)
+ && REGNO (x) >= FIRST_PSEUDO_REGISTER
+ && replacements[REGNO (x)] != NULL_RTX)
+ {
+ if (GET_MODE (x) == GET_MODE (replacements[REGNO (x)]))
+ return replacements[REGNO (x)];
+ return lowpart_subreg (GET_MODE (x), replacements[REGNO (x)],
+ GET_MODE (replacements[REGNO (x)]));
+ }
+ return NULL_RTX;
+}
+
/* Scan all the insns and delete any that are dead; i.e., they store a register
that is never used or they copy a register to itself.
{
int *counts;
rtx insn, prev;
+ rtx *replacements = NULL;
int ndead = 0;
timevar_push (TV_DELETE_TRIVIALLY_DEAD);
/* First count the number of times each register is used. */
- counts = XCNEWVEC (int, nreg);
- for (insn = insns; insn; insn = NEXT_INSN (insn))
- if (INSN_P (insn))
- count_reg_usage (insn, counts, NULL_RTX, 1);
-
+ if (MAY_HAVE_DEBUG_INSNS)
+ {
+ counts = XCNEWVEC (int, nreg * 3);
+ for (insn = insns; insn; insn = NEXT_INSN (insn))
+ if (DEBUG_INSN_P (insn))
+ count_reg_usage (INSN_VAR_LOCATION_LOC (insn), counts + nreg,
+ NULL_RTX, 1);
+ else if (INSN_P (insn))
+ {
+ count_reg_usage (insn, counts, NULL_RTX, 1);
+ note_stores (PATTERN (insn), count_stores, counts + nreg * 2);
+ }
+ /* If there can be debug insns, COUNTS are 3 consecutive arrays.
+ First one counts how many times each pseudo is used outside
+ of debug insns, second counts how many times each pseudo is
+ used in debug insns and third counts how many times a pseudo
+ is stored. */
+ }
+ else
+ {
+ counts = XCNEWVEC (int, nreg);
+ for (insn = insns; insn; insn = NEXT_INSN (insn))
+ if (INSN_P (insn))
+ count_reg_usage (insn, counts, NULL_RTX, 1);
+ /* If no debug insns can be present, COUNTS is just an array
+ which counts how many times each pseudo is used. */
+ }
/* Go from the last insn to the first and delete insns that only set unused
registers or copy a register to itself. As we delete an insn, remove
usage counts for registers it uses.
The first jump optimization pass may leave a real insn as the last
insn in the function. We must not skip that insn or we may end
- up deleting code that is not really dead. */
+ up deleting code that is not really dead.
+
+ If some otherwise unused register is only used in DEBUG_INSNs,
+ try to create a DEBUG_EXPR temporary and emit a DEBUG_INSN before
+ the setter. Then go through DEBUG_INSNs and if a DEBUG_EXPR
+ has been created for the unused register, replace it with
+ the DEBUG_EXPR, otherwise reset the DEBUG_INSN. */
for (insn = get_last_insn (); insn; insn = prev)
{
int live_insn = 0;
if (! live_insn && dbg_cnt (delete_trivial_dead))
{
- count_reg_usage (insn, counts, NULL_RTX, -1);
+ if (DEBUG_INSN_P (insn))
+ count_reg_usage (INSN_VAR_LOCATION_LOC (insn), counts + nreg,
+ NULL_RTX, -1);
+ else
+ {
+ rtx set;
+ if (MAY_HAVE_DEBUG_INSNS
+ && (set = single_set (insn)) != NULL_RTX
+ && is_dead_reg (SET_DEST (set), counts)
+ /* Used at least once in some DEBUG_INSN. */
+ && counts[REGNO (SET_DEST (set)) + nreg] > 0
+ /* And set exactly once. */
+ && counts[REGNO (SET_DEST (set)) + nreg * 2] == 1
+ && !side_effects_p (SET_SRC (set))
+ && asm_noperands (PATTERN (insn)) < 0)
+ {
+ rtx dval, bind;
+
+ /* Create DEBUG_EXPR (and DEBUG_EXPR_DECL). */
+ dval = make_debug_expr_from_rtl (SET_DEST (set));
+
+ /* Emit a debug bind insn before the insn in which
+ reg dies. */
+ bind = gen_rtx_VAR_LOCATION (GET_MODE (SET_DEST (set)),
+ DEBUG_EXPR_TREE_DECL (dval),
+ SET_SRC (set),
+ VAR_INIT_STATUS_INITIALIZED);
+ count_reg_usage (bind, counts + nreg, NULL_RTX, 1);
+
+ bind = emit_debug_insn_before (bind, insn);
+ df_insn_rescan (bind);
+
+ if (replacements == NULL)
+ replacements = XCNEWVEC (rtx, nreg);
+ replacements[REGNO (SET_DEST (set))] = dval;
+ }
+
+ count_reg_usage (insn, counts, NULL_RTX, -1);
+ ndead++;
+ }
delete_insn_and_edges (insn);
- ndead++;
}
}
+ if (MAY_HAVE_DEBUG_INSNS)
+ {
+ struct dead_debug_insn_data ddid;
+ ddid.counts = counts;
+ ddid.replacements = replacements;
+ for (insn = get_last_insn (); insn; insn = PREV_INSN (insn))
+ if (DEBUG_INSN_P (insn))
+ {
+ /* If this debug insn references a dead register that wasn't replaced
+ with an DEBUG_EXPR, reset the DEBUG_INSN. */
+ ddid.seen_repl = false;
+ if (for_each_rtx (&INSN_VAR_LOCATION_LOC (insn),
+ is_dead_debug_insn, &ddid))
+ {
+ INSN_VAR_LOCATION_LOC (insn) = gen_rtx_UNKNOWN_VAR_LOC ();
+ df_insn_rescan (insn);
+ }
+ else if (ddid.seen_repl)
+ {
+ INSN_VAR_LOCATION_LOC (insn)
+ = simplify_replace_fn_rtx (INSN_VAR_LOCATION_LOC (insn),
+ NULL_RTX, replace_dead_reg,
+ replacements);
+ df_insn_rescan (insn);
+ }
+ }
+ if (replacements)
+ free (replacements);
+ }
+
if (dump_file && ndead)
fprintf (dump_file, "Deleted %i trivially dead insns\n",
ndead);