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[Bug tree-optimization/42614] [4.4 Regression] FRE optimizes away valid code after IPA inlining
- 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: 5 Jan 2010 12:16:55 -0000
- Subject: [Bug tree-optimization/42614] [4.4 Regression] FRE optimizes away valid code after IPA inlining
- References: <bug-42614-17160@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #9 from rguenth at gcc dot gnu dot org 2010-01-05 12:16 -------
Ok, it's simple. We add false aliases to &index to both SMTs of SEntry and
STable because may_alias_p (SEntry, char) returns true as every alias-set
is a subset of alias-set zero.
But then when coming along to adding SMT aliases we do not add STable as
an alias of SEntry because they already have (false) aliases in common.
These false aliases are pruned by access_can_touch_variable later and
boom - there we go.
I have a fix.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42614