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[Bug tree-optimization/79669] New: tree-loop-vectorize generates movdqa for unaligned address
- From: "lee.duhem at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Wed, 22 Feb 2017 09:04:57 +0000
- Subject: [Bug tree-optimization/79669] New: tree-loop-vectorize generates movdqa for unaligned address
- Auto-submitted: auto-generated
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79669
Bug ID: 79669
Summary: tree-loop-vectorize generates movdqa for unaligned
address
Product: gcc
Version: 7.0.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: lee.duhem at gmail dot com
Target Milestone: ---
Created attachment 40810
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=40810&action=edit
source file to reproduce the issue
If the attached test program is compiled with -O3 on x86-64 platform, the
program will crash at a movdqa instruction which is trying to access an
unaligned address:
~/works/gcc/build0/./gcc/xgcc -B$HOME/works/gcc/build0/./gcc/ -Wall -g -O3 -c
-o t00.o t00.c
However, if it is compiled with -O3 -fno-tree-loop-vectorize on the same
platform, this program will finish successfully:
~/works/gcc/build0/./gcc/xgcc -B$HOME/works/gcc/build0/./gcc/ -Wall -g -O3
-fno-tree-loop-vectorize -c -o t00.o t00.c
And the final executable file does not include movdqa instruction at all.