[llvm] [InstCombine]Fold fcmp+select to min/max if its zero sign is missing (PR #213133)

[Yingwei Zheng via llvm-commits]

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@@ -4511,6 +4511,34 @@ static Instruction *foldSelectNegNot(SelectInst &SI,
   return nullptr;
 }
 
+// Return true if no use can observe the sign of zero of the select result,
+// looking through phis, selects and the loop back edge to the select itself.
+static bool isSelectZeroSignInsignificant(SelectInst &SI) {
+  // Bound the number of instructions to look through to keep the compile time
+  // in check.
+  constexpr unsigned MaxLookThroughNodes = 6;
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dtcxzyw wrote:

This threshold should bound the number of uses, not the number of phi/selects.


https://github.com/llvm/llvm-project/pull/213133