[llvm] [InstCombine] Enable select freeze poison folding when storing value (PR #129776)

[Yingwei Zheng via llvm-commits]

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@@ -4812,15 +4812,20 @@ Instruction *InstCombinerImpl::visitFreeze(FreezeInst &I) {
   //
   // TODO: This could use getBinopAbsorber() / getBinopIdentity() to avoid
   //       duplicating logic for binops at least.
-  auto getUndefReplacement = [&I](Type *Ty) {
-    Constant *BestValue = nullptr;
-    Constant *NullValue = Constant::getNullValue(Ty);
+  auto getUndefReplacement = [&I, &AC = this->AC, &DT = this->DT](Type *Ty) {
+    Value *BestValue = nullptr;
+    Value *NullValue = Constant::getNullValue(Ty);
     for (const auto *U : I.users()) {
-      Constant *C = NullValue;
+      Value *C = NullValue;
       if (match(U, m_Or(m_Value(), m_Value())))
         C = ConstantInt::getAllOnesValue(Ty);
       else if (match(U, m_Select(m_Specific(&I), m_Constant(), m_Value())))
         C = ConstantInt::getTrue(Ty);
+      else if (match(&I, m_Freeze(m_Poison())) &&
+               match(U, m_c_Select(m_Specific(&I), m_Value(C)))) {
+        if (!isGuaranteedNotToBeUndefOrPoison(C, &AC, &I, &DT))
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dtcxzyw wrote:

We can sink this check (without context information) after picking out a common replacement.


https://github.com/llvm/llvm-project/pull/129776