GlobalISel: Use a callback to compute constrained reg class for unallocatble registers
Summary:
constrainOperandRegClass() currently fails if it tries to constrain the
register class of an operand that is defeined with an unallocatable register
class. This patch resolves this by adding a target callback to compute
register constriants in this case.
This is required by the AMDGPU because many of its instructions have source opreands
defined with the unallocatable register classe VS_32 which is a union of two allocatable
register classes VGPR_32 and SReg_32.
Reviewers: dsanders, aditya_nandakumar
Reviewed By: aditya_nandakumar
Subscribers: rovka, kristof.beyls, tpr, llvm-commits
Differential Revision: https://reviews.llvm.org/D45991
llvm-svn: 331485
2 files changed