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[Bug tree-optimization/17064] -falias-noargument-global doesn't eliminate dead stores/loads
- From: "rguenth at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 3 Apr 2009 11:57:06 -0000
- Subject: [Bug tree-optimization/17064] -falias-noargument-global doesn't eliminate dead stores/loads
- References: <bug-17064-6527@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #16 from rguenth at gcc dot gnu dot org 2009-04-03 11:57 -------
Re-confirmed with current trunk. The issue is that PTA computes
Flow-insensitive points-to information for foo
p_1(D), points-to vars: { PARM_NOALIAS.28 } (includes global vars)
foo (int * p)
{
<bb 2>:
*p_1(D) = 1;
bar ();
*p_1(D) = 2;
return;
note the 'includes global vars' flag. Note that "fixing" this would
really make _both_ stores to *p dead, as "does-not-point-to-global"
does not mean "does-point-to-local".
A more proper definition of the effect of this flag should be given.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed|2006-01-05 14:24:50 |2009-04-03 11:57:05
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17064