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[Bug tree-optimization/74881] New: re-align optimization blocks vectorization on powerpc
- From: "amker at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Fri, 12 Aug 2016 16:20:22 +0000
- Subject: [Bug tree-optimization/74881] New: re-align optimization blocks vectorization on powerpc
- Authentication-results: sourceware.org; auth=none
- Auto-submitted: auto-generated
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=74881
Bug ID: 74881
Summary: re-align optimization blocks vectorization on powerpc
Product: gcc
Version: 7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: amker at gcc dot gnu.org
Target Milestone: ---
Hi,
gcc.dg/vect/vect-117.c starts failing with patch at r238301. After
investigation I think it exposed a latent vectorizer issue. Before patch, the
loop is vectorized but guarded by alias check that is always false. That is,
the vectorized loop will never be executed in reality. The patch only skips
known to be false alias check.
Detailed analysis and possible fix is at
https://gcc.gnu.org/ml/gcc-patches/2016-08/msg01035.html