[llvm] [llvm][instcombine] Add Missed Optimization for Folding Min Max intrinsic into PHI instruction (PR #84619)

[Yingwei Zheng via llvm-commits]

================
@@ -611,6 +611,95 @@ Instruction *InstCombinerImpl::foldPHIArgGEPIntoPHI(PHINode &PN) {
   return NewGEP;
 }
 
+/// helper function for foldPHIWithMinMax
+Instruction *
+InstCombinerImpl::foldPHIWithMinMaxHelper(PHINode &PN, Instruction *I, Value *Z,
+                                          ICmpInst::Predicate Pred) {
+
+  auto IsCondKnownTrue = [](Value *Val) -> std::optional<bool> {
+    if (!Val)
+      return std::nullopt;
+    if (match(Val, m_One()))
+      return true;
+    if (match(Val, m_Zero()))
+      return false;
+    return std::nullopt;
+  };
+
+  ICmpInst::Predicate SwappedPred =
+      ICmpInst::getNonStrictPredicate(ICmpInst::getSwappedPredicate(Pred));
+  for (unsigned OpNum = 0; OpNum != PN.getNumIncomingValues(); ++OpNum) {
+    if (auto *MinMax = dyn_cast<MinMaxIntrinsic>(PN.getIncomingValue(OpNum))) {
+      if (Pred != MinMax->getPredicate())
+        continue;
+
+      Value *X = MinMax->getLHS();
+      Value *Y = MinMax->getRHS();
+
+      SimplifyQuery Q = SQ.getWithInstruction(I);
----------------
dtcxzyw wrote:

```suggestion
      SimplifyQuery Q = SQ.getWithInstruction(PN.getIncomingBlock(OpNum)->getTerminator());
```


https://github.com/llvm/llvm-project/pull/84619