[PATCH] D59633: [PowerPC] Look through copies for compare elimination

[Jinsong Ji via Phabricator via llvm-commits]

jsji requested changes to this revision.
jsji added a comment.
This revision now requires changes to proceed.

Might miss some opportunity related to parameters instead. Please have a look. Thanks.



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Comment at: lib/Target/PowerPC/PPCInstrInfo.cpp:1669
   // Get the unique definition of SrcReg.
+  SrcReg = TRI->lookThruCopyLike(SrcReg, MRI);
   MachineInstr *MI = MRI->getUniqueVRegDef(SrcReg);
----------------
This will have some problem with parameter/return COPY:  We will get HW reg instead, wrong `MI`, then mess up the search scope in line 1802 later.
See `test/CodeGen/PowerPC/optcmp.ll` for an example.


Repository:
  rL LLVM

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https://reviews.llvm.org/D59633