[PATCH] D156448: [TwoAddressInstruction] Tweak constraining of tied operands w/undef source

[Jay Foad via Phabricator via llvm-commits]

foad added a comment.

Just trying to clarify my own thoughts:

- I have no objection to your patch, though I do wonder if we can simplify this code even more.
- The specific AMDGPU case that prompted D110944 <https://reviews.llvm.org/D110944> no longer exists, and if it or anything like it comes back, we can re-examine it afresh.
- If I was trying to fix that AMDGPU case today I think I would do it differently anyway: the part of TwoAddressInstructionPass::runOnMachineFunction that rewrites INSERT_SUBREG as COPY should probably just call getSubClassWithSubReg to constrain the dst operand when it sets the subreg.


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https://reviews.llvm.org/D156448