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

[Matt Arsenault via llvm-commits]

================
@@ -177,6 +177,15 @@ void Instruction::setNonNeg(bool b) {
                          (b * PossiblyNonNegInst::NonNeg);
 }
 
+bool Instruction::hasAllowReassocOfAllOperand() const {
----------------
arsenm wrote:

I think allowing the reassoc flag to spread to its neighbors is an overly aggressive interpretation. I think a strict interpretation where both instructions require the reassoc flag is the more expressive option. As in, I disagree with the premise of the comment in this test 

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