[PATCH] D38288: [InstCombine] Restrict transforming shared selects using SimplifySelectsFeedingBinaryOp when we cannot simplify the binary op.

[Chad Rosier via Phabricator via llvm-commits]

mcrosier added inline comments.


================
Comment at: lib/Transforms/InstCombine/InstructionCombining.cpp:740
     Value *V2 = SimplifyBinOp(Opcode, B, D, SQ.getWithInstruction(&I));
     if (V1 && V2)
       SI = Builder.CreateSelect(A, V2, V1);
----------------
I wonder if something like this would work:

    bool SelectsHaveOneUse = LHS->hasOneUse() && RHS->hasOneUse();
    if (V1 && V2)
      SI = Builder.CreateSelect(A, V2, V1);
    else if (V2 && SelectsHaveOneUse)
      SI = Builder.CreateSelect(A, V2, Builder.CreateBinOp(Opcode, C, E));
    else if (V1 && SelectsHaveOneUse)
      SI = Builder.CreateSelect(A, Builder.CreateBinOp(Opcode, B, D), V1);


https://reviews.llvm.org/D38288