[llvm] [InstCombine] Fix the correctness of missing check reassoc attribute (PR #71277)

[Matt Arsenault via llvm-commits]

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@@ -781,7 +781,7 @@ Instruction *InstCombinerImpl::visitFMul(BinaryOperator &I) {
   if (Value *V = SimplifySelectsFeedingBinaryOp(I, Op0, Op1))
     return replaceInstUsesWith(I, V);
 
-  if (I.hasAllowReassoc())
+  if (I.hasAllowReassoc() && I.hasAllowReassocOfAllOperand())
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arsenm wrote:

I think this is a bit too specific of a query to add to Instruction. It will also be imprecise in cases where the source is a constant / load /argument or other non-instruction source 

https://github.com/llvm/llvm-project/pull/71277