[PATCH] D143371: [DAG][AArch64][ARM] Recognize hadd from wrapping flags.

Mon Feb 6 05:56:40 PST 2023

spatel accepted this revision.
spatel added a comment.
This revision is now accepted and ready to land.

LGTM - see inline for possible logic simplification.

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Comment at: llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp:959-965
     if ((ConstOp = isConstOrConstSplat(Op1, DemandedElts)) &&
         ConstOp->isOne()) {
       ExtOpA = Op2;
       ExtOpB = Op3;
+      Add2 = A;
       return true;
     }
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It's semi-independent of this patch, but do we need this clause? We're looking for a "1" constant, so it would always get canonicalized to operand 1 of an incoming 'add'?

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https://reviews.llvm.org/D143371