[llvm] [InstCombine][AMDGPU] Disable PtrReplacer when select has mismatch AS. (PR #98456)

[Shilei Tian via llvm-commits]

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@@ -270,16 +270,54 @@ class PointerReplacer {
     unsigned ToAS = ASC->getDestAddressSpace();
     return (FromAS == ToAS) || IC.isValidAddrSpaceCast(FromAS, ToAS);
   }
+  bool FoundASC(const Value *TrueOp) const;
+  bool hasConflictingAS(const Instruction *I) const;
 
   SmallPtrSet<Instruction *, 32> ValuesToRevisit;
+  SmallPtrSet<Instruction *, 32> ValuesToRevisitAS;
   SmallSetVector<Instruction *, 4> Worklist;
   MapVector<Value *, Value *> WorkMap;
   InstCombinerImpl &IC;
   Instruction &Root;
   unsigned FromAS;
+  bool HasASC = false;
 };
 } // end anonymous namespace
 
+/// Return true iff valid addrspacecast is found on
+/// path from end of branch to root of tree.
+bool PointerReplacer::FoundASC(const Value *Op) const {
+  const Instruction *TI;
+  while ((TI = dyn_cast<Instruction>(Op)) != &Root) {
+    if (auto *ASC = dyn_cast<AddrSpaceCastInst>(Op))
+      if (isEqualOrValidAddrSpaceCast(ASC, FromAS))
+        return true;
+    if (TI && isa<Instruction>(TI->getOperand(0)))
+      Op = TI->getOperand(0);
+    else if (TI)
+      Op = TI->getOperand(1);
+    else
+      break;
+  }
+  return false;
+}
+
+/// Return true iff valid ASCs are found on both true and false
+/// paths from the select to the root alloca.
+bool PointerReplacer::hasConflictingAS(const Instruction *I) const {
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shiltian wrote:

I'd make it `const SelectInst *SI`.

https://github.com/llvm/llvm-project/pull/98456