[PATCH] D54719: [Intrinsic] Signed Fixed Point Multiplication Intrinsic

[Craig Topper via Phabricator via llvm-commits]

craig.topper added inline comments.


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Comment at: llvm/include/llvm/Target/TargetSelectionDAG.td:383
 def usubsat    : SDNode<"ISD::USUBSAT"   , SDTIntBinOp>;
+def smulfix    : SDNode<"ISD::SMULFIX"   , SDTIntBinOp, [SDNPCommutative]>;
 
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ebevhan wrote:
> It's marked SDTIntBinOp, but is supposed to have three input operands. I think these nodes might need a new SDT.
> 
> Also, multiplication is obviously commutative, but I don't know if SDNPCommutative works on nodes that have anything except two operands. It might not have an effect at all. Someone who knows more about DAG might have more info on that.
Tablegen should use the first two operands as the commutative ones. It used to be an error or an assertion. But I changed it sometime in the last year or so to make it work for FMA in X86.


Repository:
  rL LLVM

https://reviews.llvm.org/D54719