[llvm] [ConstraintElimination] Add eq/ne facts to signed constraint system (PR #121423)

[Yingwei Zheng via llvm-commits]

================
@@ -1580,10 +1594,20 @@ static bool checkOrAndOpImpliedByOther(
 void ConstraintInfo::addFact(CmpInst::Predicate Pred, Value *A, Value *B,
                              unsigned NumIn, unsigned NumOut,
                              SmallVectorImpl<StackEntry> &DFSInStack) {
+  addFactImpl(Pred, A, B, NumIn, NumOut, DFSInStack, false);
+  // If the Pred is eq/ne, also add the fact to signed system.
+  if (Pred == ICmpInst::ICMP_EQ || Pred == ICmpInst::ICMP_NE)
----------------
dtcxzyw wrote:

```suggestion
  if (ICmpInst::isEquality(Pred))
```

https://github.com/llvm/llvm-project/pull/121423