[llvm] [InstCombine] Allow simplifying FP selects of cmpxchg instructions. (PR #181977)

[Antonio Frighetto via llvm-commits]

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@@ -2773,6 +2783,17 @@ static Value *foldSelectCmpXchg(SelectInst &SI) {
     return dyn_cast<AtomicCmpXchgInst>(Extract->getAggregateOperand());
   };
 
+  // Check if the compare value of a cmpxchg matches another value.
+  auto isCompareSameAsValue = [](Value *C, Value *V) {
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antoniofrighetto wrote:

Nit on naming:
```suggestion
  auto isCompareSameAsValue = [](Value *CmpVal, Value *SelVal) {
```

https://github.com/llvm/llvm-project/pull/181977