[PATCH] D93191: [PowerPC] Fold select_cc constants when comparing zero into trivial ops

[ChenZheng via Phabricator via llvm-commits]

shchenz added inline comments.


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Comment at: llvm/lib/Target/PowerPC/PPCISelLowering.cpp:16726
+  if (!N2C || !N3C || !VT.isInteger() || !CmpOpVT.isInteger() ||
+      !isNullConstant(N1) || CC != ISD::SETLT || !CmpOpVT.bitsGE(VT))
+    return SDValue();
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Can we handle `CmpOpVT.bitsLT(VT)` case by using extend operation?


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Comment at: llvm/lib/Target/PowerPC/PPCISelLowering.cpp:16748
+
+  unsigned LastOp = FalseVal.slt(TrueVal) ? ISD::ADD : ISD::SUB;
+  // In general, select_cc x, 0, y, z, lt ->
----------------
Is it better to check `Diff.isNegative()`?


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Comment at: llvm/test/CodeGen/PowerPC/select.ll:7
 ; RUN:   -mtriple=powerpc-linux-gnu < %s | FileCheck \
 ; RUN:   -check-prefix=CHECK-32 %s
 
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Could you please add some run lines for AIX too?


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D93191/new/

https://reviews.llvm.org/D93191