[clang] Replace uses of CreatePointerBitCastOrAddrSpaceCast (NFC) (#68277)

With opaque pointers, `CreatePointerBitCastOrAddrSpaceCast` can be replaced with `CreateAddrSpaceCast`.
Replace or remove uses of `CreatePointerBitCastOrAddrSpaceCast`.

Opaque pointer cleanup effort.

Author: JOE1994

clang/lib/CodeGen/CGCall.cpp

@@ -1380,7 +1380,7 @@ static void CreateCoercedStore(llvm::Value *Src,
   llvm::PointerType *DstPtrTy = llvm::dyn_cast<llvm::PointerType>(DstTy);
   if (SrcPtrTy && DstPtrTy &&
       SrcPtrTy->getAddressSpace() != DstPtrTy->getAddressSpace()) {
-    Src = CGF.Builder.CreatePointerBitCastOrAddrSpaceCast(Src, DstTy);
+    Src = CGF.Builder.CreateAddrSpaceCast(Src, DstTy);
     CGF.Builder.CreateStore(Src, Dst, DstIsVolatile);
     return;
   }

clang/lib/CodeGen/CodeGenFunction.cpp

@@ -1121,11 +1121,9 @@ void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
         Address(&*AI, ConvertType(RetTy),
                 CurFnInfo->getReturnInfo().getIndirectAlign(), KnownNonNull);
     if (!CurFnInfo->getReturnInfo().getIndirectByVal()) {
-      ReturnValuePointer =
-          CreateDefaultAlignTempAlloca(Int8PtrTy, "result.ptr");
-      Builder.CreateStore(Builder.CreatePointerBitCastOrAddrSpaceCast(
-                              ReturnValue.getPointer(), Int8PtrTy),
-                          ReturnValuePointer);
+      ReturnValuePointer = CreateDefaultAlignTempAlloca(
+          ReturnValue.getPointer()->getType(), "result.ptr");
+      Builder.CreateStore(ReturnValue.getPointer(), ReturnValuePointer);
     }
   } else if (CurFnInfo->getReturnInfo().getKind() == ABIArgInfo::InAlloca &&
              !hasScalarEvaluationKind(CurFnInfo->getReturnType())) {

clang/lib/CodeGen/ItaniumCXXABI.cpp

@@ -3095,9 +3095,6 @@ void ItaniumCXXABI::EmitThreadLocalInitFuncs(
       CharUnits Align = CGM.getContext().getDeclAlign(VD);
       Val = Builder.CreateAlignedLoad(Var->getValueType(), Val, Align);
     }
-    if (Val->getType() != Wrapper->getReturnType())
-      Val = Builder.CreatePointerBitCastOrAddrSpaceCast(
-          Val, Wrapper->getReturnType(), "");
 
     Builder.CreateRet(Val);
   }

clang/lib/CodeGen/TargetInfo.cpp

@@ -137,7 +137,7 @@ llvm::Value *TargetCodeGenInfo::performAddrSpaceCast(
   if (auto *C = dyn_cast<llvm::Constant>(Src))
     return performAddrSpaceCast(CGF.CGM, C, SrcAddr, DestAddr, DestTy);
   // Try to preserve the source's name to make IR more readable.
-  return CGF.Builder.CreatePointerBitCastOrAddrSpaceCast(
+  return CGF.Builder.CreateAddrSpaceCast(
       Src, DestTy, Src->hasName() ? Src->getName() + ".ascast" : "");
 }
 

llvm/include/llvm/IR/IRBuilder.h

@@ -2146,6 +2146,9 @@ class IRBuilderBase {
     return Insert(CastInst::CreatePointerCast(V, DestTy), Name);
   }
 
+  // With opaque pointers enabled, this can be substituted with
+  // CreateAddrSpaceCast.
+  // TODO: Replace uses of this method and remove the method itself.
   Value *CreatePointerBitCastOrAddrSpaceCast(Value *V, Type *DestTy,
                                              const Twine &Name = "") {
     if (V->getType() == DestTy)