Summary:
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.
Reviewers: MatzeB, tstellar
Reviewed By: MatzeB
Subscribers: jvesely, nhaehnle, llvm-commits
Differential Revision: https://reviews.llvm.org/D52558
llvm-svn: 343417
Bjorn Pettersson