Mikael Holmen af14a21e50 [UnreachableBlockElim] Check return value of constrainRegClass(). ...

Summary:
MachineRegisterInfo::constrainRegClass() can fail if two register classes
don't have a common subclass or if the register class doesn't contain
enough registers. Check the return value before trying to remove Phi nodes,
and if we can't constrain, we output a COPY instead of simply replacing
registers.

Reviewers: kparzysz, david2050, wmi

Reviewed By: kparzysz

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D32999

llvm-svn: 302622

2017-05-10 06:33:43 +00:00

8.2 KiB

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