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Fix PR rtl-optimization/42461
- From: Eric Botcazou <ebotcazou at adacore dot com>
- To: gcc-patches at gcc dot gnu dot org
- Date: Mon, 7 Jun 2010 23:02:03 +0200
- Subject: Fix PR rtl-optimization/42461
This is a missed optimization due the EH rewrite from last year: the RTL DCE
pass doesn't eliminate calls to pure/const functions any longer.
Tested on x86_64-suse-linux. I'd like to put this on the 4.5 branch as well,
any objections from RMs?
2010-06-07 Eric Botcazou <ebotcazou@adacore.com>
PR rtl-optimization/42461
* dce.c (deletable_insn_p): Return true for const or pure calls again.
* except.c (insn_could_throw_p): Return false if !flag_exceptions.
2010-06-07 Eric Botcazou <ebotcazou@adacore.com>
* gcc.dg/pr42461.c: New test.
--
Eric Botcazou
Index: dce.c
===================================================================
--- dce.c (revision 160359)
+++ dce.c (working copy)
@@ -94,14 +94,6 @@ deletable_insn_p (rtx insn, bool fast, b
rtx body, x;
int i;
- /* Don't delete jumps, notes and the like. */
- if (!NONJUMP_INSN_P (insn))
- return false;
-
- /* Don't delete insns that can throw. */
- if (!insn_nothrow_p (insn))
- return false;
-
if (CALL_P (insn)
/* We cannot delete calls inside of the recursive dce because
this may cause basic blocks to be deleted and this messes up
@@ -116,6 +108,14 @@ deletable_insn_p (rtx insn, bool fast, b
&& !RTL_LOOPING_CONST_OR_PURE_CALL_P (insn)))
return find_call_stack_args (insn, false, fast, arg_stores);
+ /* Don't delete jumps, notes and the like. */
+ if (!NONJUMP_INSN_P (insn))
+ return false;
+
+ /* Don't delete insns that can throw. */
+ if (!insn_nothrow_p (insn))
+ return false;
+
body = PATTERN (insn);
switch (GET_CODE (body))
{
Index: except.c
===================================================================
--- except.c (revision 160359)
+++ except.c (working copy)
@@ -1617,6 +1617,8 @@ make_reg_eh_region_note_nothrow_nononloc
bool
insn_could_throw_p (const_rtx insn)
{
+ if (!flag_exceptions)
+ return false;
if (CALL_P (insn))
return true;
if (INSN_P (insn) && cfun->can_throw_non_call_exceptions)
/* PR rtl-optimization/42461 */
/* Reported by Patrick Pelissier <patrick.pelissier@gmail.com> */
/* { dg-do link } */
/* { dg-options "-O" } */
extern int link_failure (int) __attribute__ ((pure));
int main (void)
{
if (link_failure (0) < 1)
__builtin_unreachable ();
return 0;
}