[PATCH] D109953: [X86] Combine the FADD(A, FMA(B, C, 0)) to FMA(B, C, A)

[LiuChen via Phabricator via llvm-commits]

LiuChen3 added inline comments.


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Comment at: llvm/lib/Target/X86/X86ISelLowering.cpp:47481
 
 //  Try to combine the following nodes
 //  t21: v16f32 = X86ISD::VFMULC/VFCMULC t7, t8
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xbolva00 wrote:
> Do we really need this output here? Simplify it a bit? Something like you wrote "Combine the FADD(A, FMA(B, C, 0)) to FMA(B, C, A)"?
Good idea.


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Comment at: llvm/lib/Target/X86/X86ISelLowering.cpp:47522
   SDValue RHS = N->getOperand(1);
   SDValue CFmul, FAddOp1;
+  auto GetCFmulFrom = [&CFmul, &AllowContract, &DAG](SDValue N) -> bool {
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pengfei wrote:
> I think we can use `bool IsConj`, `SDValue MulOp0, MulOp0` instead of `CFmul`. Then you don't need to create a temp mul node.
It seems we create more temp node. Is it better?


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https://reviews.llvm.org/D109953