[PATCH] D68813: [AMDGPU] Handle undef old operand in DPP combine

[Valery Pykhtin via Phabricator via llvm-commits]

vpykhtin accepted this revision.
vpykhtin added a comment.
This revision is now accepted and ready to land.
Herald added a subscriber: wuzish.

LGTM.



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Comment at: llvm/lib/Target/AMDGPU/GCNDPPCombine.cpp:181
       assert(isOfRegClass(CombOldVGPR, AMDGPU::VGPR_32RegClass, *MRI));
-      DPPInst.addReg(CombOldVGPR.Reg, 0, CombOldVGPR.SubReg);
+      auto *Def = getVRegSubRegDef(CombOldVGPR, *MRI);
+      DPPInst.addReg(CombOldVGPR.Reg, Def ? 0 : RegState::Undef,
----------------
ok, I missed the case when there is no defining instruction. It is not very good that the def is searched again, but lets submit this for the fix.


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  https://reviews.llvm.org/D68813/new/

https://reviews.llvm.org/D68813