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[DAGCombiner] Fix invalid alias analysis.
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Authored by courbet on May 13 2019, 1:08 AM.

Details

Summary

When we know for sure whether two addresses do or do not alias, we
should immediately return from DAGCombiner::isAlias().

I think this comes from a bad copy/paste, Sorry for not catching that during the
code review.

Fixes PR41855.

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Repository
rL LLVM

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courbet created this revision.May 13 2019, 1:08 AM
Herald added a project: Restricted Project. · View Herald TranscriptMay 13 2019, 1:08 AM
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courbet marked an inline comment as done.May 13 2019, 1:54 AM
courbet added inline comments.
llvm/test/CodeGen/X86/lifetime-alias.ll
44 ↗(On Diff #199221)

Note how the string size for "FunnyItWorkedLastTime" was incorrectly set to 15 before, and is now correctly set to 21.

gchatelet accepted this revision.May 13 2019, 2:00 AM
This revision is now accepted and ready to land.May 13 2019, 2:00 AM
This revision was automatically updated to reflect the committed changes.
echristo added inline comments.
llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
19802

Can you comment this? Given it's already caused a problem and isn't obvious what's going on necessarily.

courbet marked 2 inline comments as done.May 15 2019, 1:17 AM
courbet added inline comments.
llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
19802

Sure.