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Fix shl folding in DAG combiner.
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Authored by chfast on Jun 22 2015, 7:58 AM.

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Summary

The code responsible for shl folding in the DAGCombiner was assuming incorrectly that all constants are less than 64 bits. This patch simply changes the way values are compared.

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rL LLVM

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chfast updated this revision to Diff 28109.Jun 22 2015, 7:58 AM
chfast retitled this revision from to Fix shl folding in DAG combiner..
chfast updated this object.
chfast edited the test plan for this revision. (Show Details)
chfast added a subscriber: Unknown Object (MLST).
andreadb accepted this revision.Jun 22 2015, 8:39 AM
andreadb added a reviewer: andreadb.
andreadb added subscribers: test, andreadb.

Hi Pawel,

The change looks good to me.
You can simplify the test case (see comment below).

Thanks,
Andrea

test/CodeGen/X86/fold-vector-shl-crash.ll
4–8 ↗(On Diff #28109)

if you define @test as a function returning a <2 x i256> vector value, then you can get rid of basic block 'Loop' and simply return %B.
Basically, the loop is not needed to reproduce the crash in the dag combiner.

This revision is now accepted and ready to land.Jun 22 2015, 8:39 AM
chfast updated this revision to Diff 28117.Jun 22 2015, 8:53 AM
chfast edited edge metadata.
  • Simplify the regression test.
This revision was automatically updated to reflect the committed changes.