[PATCH] D53739: InstCombine: Avoid introducing posion values when lowering llvm.amdgcn.[us]bfe

[Tom Stellard via Phabricator via llvm-commits]

tstellar created this revision.
tstellar added a reviewer: arsenm.
Herald added subscribers: nhaehnle, wdng, jvesely.

When the 3rd argument to these intrinsics is zero, lowering them
to shift instructions produces posion values, since we end up with
shift amounts equal to the number of bits in the shifted value.  This
means we can only lower these intrinsics if we can prove that the
3rd argument is not zero.


Repository:
  rL LLVM

https://reviews.llvm.org/D53739

Files:
  lib/Transforms/InstCombine/InstCombineCalls.cpp
  test/Transforms/InstCombine/AMDGPU/amdgcn-intrinsics.ll

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