[llvm] [InstCombine]combine mul(abs(x), abs(y)) to abs(mul(x, y)) (PR #78395)

[Nikita Popov via llvm-commits]

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@@ -330,6 +330,23 @@ Instruction *InstCombinerImpl::visitMul(BinaryOperator &I) {
       return BinaryOperator::CreateMul(X, X);
   }
 
+  {
+    Value *X, *Y, *Z;
+    // abs(X) * abs(Y) -> abs(X * Y)
+    // nabs(X) * nabs(Y) -> abs(X * Y)
+    SelectPatternFlavor SPF0 = matchSelectPattern(Op0, X, Z).Flavor;
+    SelectPatternFlavor SPF1 = matchSelectPattern(Op1, Y, Z).Flavor;
+    if ((SPF0 == SPF1) && (SPF0 == SPF_ABS || SPF0 == SPF_NABS))
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nikic wrote:

Remove SPF handling.

https://github.com/llvm/llvm-project/pull/78395