[PATCH] D76585: [PowerPC] Require NSZ flag for c-a*b to FNMSUB
Qing Shan Zhang via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Tue Apr 14 19:03:36 PDT 2020
steven.zhang added inline comments.
================
Comment at: llvm/lib/Target/PowerPC/PPCISelLowering.cpp:15767
+ OptForSize, Cost, Depth + 1);
+ if (Cost == NegatibleCost::Expensive)
+ return SDValue();
----------------
You should check the value of NegN2 instead of the cost though their semantics might be the same.
================
Comment at: llvm/lib/Target/PowerPC/PPCISelLowering.cpp:15783
+
+ if (N0Cost < N1Cost)
+ return DAG.getNode(Opc, SDLoc(Op), VT, NegN0, N1, NegN2, Flags);
----------------
Please refer to how we did for FMA. i.e. Your implementation has problems when A=neutral, B=neutral, and C=cheaper
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D76585/new/
https://reviews.llvm.org/D76585
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