[llvm] [ValueTracking] Refactor `isKnownNonEqualFromContext` (PR #127388)

[Ramkumar Ramachandra via llvm-commits]

================
@@ -3786,6 +3786,63 @@ static bool isNonEqualPointersWithRecursiveGEP(const Value *A, const Value *B,
           (StartOffset.sle(OffsetB) && StepOffset.isNegative()));
 }
 
+static bool isKnownNonEqualFromContext(const Value *V1, const Value *V2,
+                                       unsigned Depth, const SimplifyQuery &Q) {
+  if (!Q.CxtI)
+    return false;
+
+  // Try to infer NonEqual based on information from dominating conditions.
+  if (Q.DC && Q.DT) {
+    auto IsKnownNonEqualFromDominatingCondition = [&](const Value *V) {
+      for (BranchInst *BI : Q.DC->conditionsFor(V)) {
+        Value *Cond = BI->getCondition();
+        BasicBlockEdge Edge0(BI->getParent(), BI->getSuccessor(0));
+        if (Q.DT->dominates(Edge0, Q.CxtI->getParent()) &&
+            isImpliedCondition(Cond, ICmpInst::ICMP_NE, V1, V2, Q.DL,
+                               /*LHSIsTrue=*/true, Depth)
+                .value_or(false))
+          return true;
+
+        BasicBlockEdge Edge1(BI->getParent(), BI->getSuccessor(1));
+        if (Q.DT->dominates(Edge1, Q.CxtI->getParent()) &&
+            isImpliedCondition(Cond, ICmpInst::ICMP_NE, V1, V2, Q.DL,
+                               /*LHSIsTrue=*/false, Depth)
+                .value_or(false))
+          return true;
+      }
+
+      return false;
+    };
+
+    if (IsKnownNonEqualFromDominatingCondition(V1) ||
+        IsKnownNonEqualFromDominatingCondition(V2))
+      return true;
+  }
+
+  if (!Q.AC)
+    return false;
+
+  // Try to infer NonEqual based on information from assumptions.
+  for (auto &AssumeVH : Q.AC->assumptionsFor(V1)) {
+    if (!AssumeVH)
+      continue;
----------------
artagnon wrote:

I wonder if this check is dead?

https://github.com/llvm/llvm-project/pull/127388