[PATCH] D52558: [PHIElimination] Lower a PHI node with only undef uses as IMPLICIT_DEF

[Bjorn Pettersson via Phabricator via llvm-commits]

bjope created this revision.
Herald added subscribers: nhaehnle, jvesely.

The lowering of PHI nodes used to detect if all inputs originated
from IMPLICIT_DEF's. If so the PHI node was replaced by an
IMPLICIT_DEF. Now we also consider undef uses when checking the
inputs. So if all inputs are implicitly defined or undef we
lower the PHI to an IMPLICIT_DEF. This makes
PHIElimination::LowerPHINode more consistent as it checks
both implicit and undef properties at later stages.


Repository:
  rL LLVM

https://reviews.llvm.org/D52558

Files:
  lib/CodeGen/PHIElimination.cpp
  test/CodeGen/AMDGPU/phi-elimination-assertion.mir

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