[llvm] [InstCombine] Add fold for fabs(-x) -> fabs(x) (PR #94183)

[Matt Arsenault via llvm-commits]

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@@ -2517,6 +2517,13 @@ Instruction *InstCombinerImpl::visitCallInst(CallInst &CI) {
   }
   case Intrinsic::fabs: {
     Value *Cond, *TVal, *FVal;
+    Value* Arg = II->getArgOperand(0);
+    Value* X;
+    // fabs (-X) --> fabs (X)
+    if (match(Arg, m_FNeg(m_Value(X)))) {
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arsenm wrote:

Somewhere is a strip sign operations helper function that also covers copysign 

https://github.com/llvm/llvm-project/pull/94183