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[multiple changes] 

2007-07-01  Richard Sandiford  <richard@codesourcery.com>

	Unreverting Richard's Revert of:

	2007-06-27  Richard Sandiford  <richard@codesourcery.com>

	* dce.c (deletable_insn_p_1): New function, split out from...
	(deletable_insn_p): ...here.  Only treat bare USEs and CLOBBERs
	specially, not those inside PARALLELs.  Remove BODY argument
	and adjust recursive call accordingly.
	(prescan_insns_for_dce): Update call to delete_insn_p.

From-SVN: r126168
This commit is contained in:
Richard Sandiford 2007-07-01 14:43:47 +00:00 committed by Kenneth Zadeck
parent 7ee1ad8483
commit d4d7f1d1bb
2 changed files with 52 additions and 24 deletions
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12
gcc/ChangeLog
View File

@ -1,3 +1,15 @@
2007-07-01 Richard Sandiford <richard@codesourcery.com>
Unreverting Richard's Revert of:
2007-06-27 Richard Sandiford <richard@codesourcery.com>
* dce.c (deletable_insn_p_1): New function, split out from...
(deletable_insn_p): ...here. Only treat bare USEs and CLOBBERs
specially, not those inside PARALLELs. Remove BODY argument
and adjust recursive call accordingly.
(prescan_insns_for_dce): Update call to delete_insn_p.
2007-07-01 Vladimir Yanovsky <yanov@il.ibm.com>
Revital Eres <eres@il.ibm.com>

64
gcc/dce.c
View File

@ -58,16 +58,15 @@ static bitmap_obstack dce_tmp_bitmap_obstack;
static sbitmap marked = NULL;
/* Return true if INSN with BODY is a normal instruction that can be
deleted by the DCE pass. */
/* A subroutine for which BODY is part of the instruction being tested;
either the top-level pattern, or an element of a PARALLEL. The
instruction is known not to be a bare USE or CLOBBER. */
static bool
deletable_insn_p (rtx insn, rtx body, bool fast)
deletable_insn_p_1 (rtx body)
{
rtx x;
switch (GET_CODE (body))
{
case USE:
case PREFETCH:
case TRAP_IF:
/* The UNSPEC case was added here because the ia-64 claims that
@ -79,6 +78,35 @@ deletable_insn_p (rtx insn, rtx body, bool fast)
case UNSPEC:
return false;
default:
if (volatile_insn_p (body))
return false;
if (flag_non_call_exceptions && may_trap_p (body))
return false;
return true;
}
}
/* Return true if INSN is a normal instruction that can be deleted by
the DCE pass. */
static bool
deletable_insn_p (rtx insn, bool fast)
{
rtx body, x;
int i;
if (!NONJUMP_INSN_P (insn))
return false;
body = PATTERN (insn);
switch (GET_CODE (body))
{
case USE:
return false;
case CLOBBER:
if (fast)
{
@ -88,32 +116,20 @@ deletable_insn_p (rtx insn, rtx body, bool fast)
x = XEXP (body, 0);
return REG_P (x) && (!HARD_REGISTER_P (x) || reload_completed);
}
else
else
/* Because of the way that use-def chains are built, it is not
possible to tell if the clobber is dead because it can
never be the target of a use-def chain. */
return false;
case PARALLEL:
{
int i;
for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
if (!deletable_insn_p (insn, XVECEXP (body, 0, i), fast))
return false;
return true;
}
for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
if (!deletable_insn_p_1 (XVECEXP (body, 0, i)))
return false;
return true;
default:
if (!NONJUMP_INSN_P (insn))
return false;
if (volatile_insn_p (body))
return false;
if (flag_non_call_exceptions && may_trap_p (body))
return false;
return true;
return deletable_insn_p_1 (body);
}
}
@ -369,7 +385,7 @@ prescan_insns_for_dce (bool fast)
rtx note = find_reg_note (insn, REG_LIBCALL_ID, NULL_RTX);
if (note)
mark_libcall (insn, fast);
else if (deletable_insn_p (insn, PATTERN (insn), fast))
else if (deletable_insn_p (insn, fast))
mark_nonreg_stores (PATTERN (insn), insn, fast);
else
mark_insn (insn, fast);