[llvm] [InstCombine] Fold abs(a * abs(b)) --> abs(a * b) (PR #78110)

[via llvm-commits]

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@@ -1601,6 +1601,15 @@ Instruction *InstCombinerImpl::visitCallInst(CallInst &CI) {
       return CastInst::Create(Instruction::ZExt, NarrowAbs, II->getType());
     }
 
+    // abs(a * abs(b)) --> abs(a * b)
+    Value *A, *B;
+    if (match(IIOperand,
+              m_OneUse(m_c_Mul(m_Value(A),
+                               m_Intrinsic<Intrinsic::abs>(m_Value(B)))))) {
+      Value *New = Builder.CreateMul(A, B);
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goldsteinn wrote:

Ah, seems to only be if the abs precludes INT_MIN. (outer abs)


https://github.com/llvm/llvm-project/pull/78110