[PATCH] D120813: AMDGPU: Skip folding REG_SEQUENCE if found unknown regclasses for its users.

[Christudasan Devadasan via Phabricator via llvm-commits]

cdevadas added inline comments.


================
Comment at: llvm/lib/Target/AMDGPU/SIFoldOperands.cpp:1602
   unsigned OpIdx = Op - &UseMI->getOperand(0);
+  if (TII->isUnknownRegClass(*UseMI, OpIdx))
+    return false;
----------------
foad wrote:
> You could just use TargetInstrInfo::getRegClass(InstDesc, OpIdx, TRI, MF) instead of TRI->getRegClass and it would do all these checks for you already.
We can't use that equivalent of `getRegClass` here. The call to `adjustAllocatableRegClass` inside it would change AV classes to V thereby disabling the folding in almost all valid cases.



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  https://reviews.llvm.org/D120813/new/

https://reviews.llvm.org/D120813