[llvm] Update foldFMulReassoc to respect absent fast-math flags (PR #88589)

[Matt Arsenault via llvm-commits]

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@@ -311,6 +312,31 @@ class BinaryOperator : public Instruction {
     return BO;
   }
 
+  static BinaryOperator *
+  CreateWithFMF(BinaryOps Opc, Value *V1, Value *V2, FastMathFlags FMF,
+                const Twine &Name = "", Instruction *InsertBefore = nullptr) {
+    BinaryOperator *BO = Create(Opc, V1, V2, Name, InsertBefore);
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arsenm wrote:

If you added a new operand/overload to Create, can you avoid the new include? 

https://github.com/llvm/llvm-project/pull/88589