[llvm] [InstCombine] Remove m_OneUse requirement only for max, not min (PR #81505)

[via llvm-commits]

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@@ -2288,11 +2288,18 @@ Instruction *InstCombinerImpl::visitCallInst(CallInst &CI) {
 
     // max X, -X --> fabs X
     // min X, -X --> -(fabs X)
-    // TODO: Remove one-use limitation? That is obviously better for max.
-    //       It would be an extra instruction for min (fnabs), but that is
-    //       still likely better for analysis and codegen.
-    if ((match(Arg0, m_OneUse(m_FNeg(m_Value(X)))) && Arg1 == X) ||
-        (match(Arg1, m_OneUse(m_FNeg(m_Value(X)))) && Arg0 == X)) {
+    // TODO: Remove one-use limitation? That is obviously better for max,
+    // hence why we don't check for one-use for that. However,
+    // it would be an extra instruction for min (fnabs), but
+    // that is still likely better for analysis and codegen.
+    auto IsMinMaxOrXNegX = [IID, &X](Value *Op0, Value *Op1) {
+      if (match(Op0, m_FNeg(m_Value(X))) && match(Op1, m_Specific(X)))
+        return Op0->hasOneUse() ||
+               (IID != Intrinsic::minimum && IID != Intrinsic::minnum);
+      return false;
+    };
+
+    if (IsMinMaxOrXNegX(Arg0, Arg1) || IsMinMaxOrXNegX(Arg1, Arg0)) {
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goldsteinn wrote:

Doesn't seem to be the case: https://godbolt.org/z/d9Gqqdneb
either way, its generally not reliable enough to rely on a true canonicalization.

https://github.com/llvm/llvm-project/pull/81505