[clang] [clang][CodeGen] Make `UnqualPtrTy` truly unqualified (PR #94388)

[Alex Voicu via cfe-commits]

https://github.com/AlexVlx created https://github.com/llvm/llvm-project/pull/94388

At the moment we alias `UnqualPtrTy` with the other default AS pointer types, which means that for certain targets using it doesn't actually yield an unqualified pointer. This patch changes that so that it does exactly what it says on the tin, under the assumption that if someone asks for an unqualified pointer they do so knowingly and expect to get exactly that.

>From cdf95a804614950167d2d4df227d06a86a70d4bb Mon Sep 17 00:00:00 2001
From: Alex Voicu <alexandru.voicu at amd.com>
Date: Tue, 4 Jun 2024 19:52:28 +0100
Subject: [PATCH] Unqualified `ptr`s should be truly unqualified, and not AS0
 ptrs.

---
 clang/lib/CodeGen/CodeGenModule.cpp  | 1 +
 clang/lib/CodeGen/CodeGenTypeCache.h | 4 +++-
 clang/lib/CodeGen/ItaniumCXXABI.cpp  | 6 +++---
 3 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index be7bf0b72dc0c..b58ca03ce69da 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -368,6 +368,7 @@ CodeGenModule::CodeGenModule(ASTContext &C,
   IntTy = llvm::IntegerType::get(LLVMContext, C.getTargetInfo().getIntWidth());
   IntPtrTy = llvm::IntegerType::get(LLVMContext,
     C.getTargetInfo().getMaxPointerWidth());
+  UnqualPtrTy = llvm::PointerType::getUnqual(LLVMContext);
   Int8PtrTy = llvm::PointerType::get(LLVMContext,
                                      C.getTargetAddressSpace(LangAS::Default));
   const llvm::DataLayout &DL = M.getDataLayout();
diff --git a/clang/lib/CodeGen/CodeGenTypeCache.h b/clang/lib/CodeGen/CodeGenTypeCache.h
index e273ebe3b060f..3b659bc182aa4 100644
--- a/clang/lib/CodeGen/CodeGenTypeCache.h
+++ b/clang/lib/CodeGen/CodeGenTypeCache.h
@@ -51,9 +51,11 @@ struct CodeGenTypeCache {
     llvm::IntegerType *PtrDiffTy;
   };
 
+  /// unqualified void*
+  llvm::PointerType *UnqualPtrTy;
+
   /// void*, void** in the target's default address space (often 0)
   union {
-    llvm::PointerType *UnqualPtrTy;
     llvm::PointerType *VoidPtrTy;
     llvm::PointerType *Int8PtrTy;
     llvm::PointerType *VoidPtrPtrTy;
diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index 8427286dee887..8952e7ca072da 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -4656,14 +4656,14 @@ static void InitCatchParam(CodeGenFunction &CGF,
   auto catchRD = CatchType->getAsCXXRecordDecl();
   CharUnits caughtExnAlignment = CGF.CGM.getClassPointerAlignment(catchRD);
 
-  llvm::Type *PtrTy = CGF.UnqualPtrTy; // addrspace 0 ok
+  llvm::Type *PtrTy = CGF.UnqualPtrTy; // unqualified is ok
 
   // Check for a copy expression.  If we don't have a copy expression,
   // that means a trivial copy is okay.
   const Expr *copyExpr = CatchParam.getInit();
   if (!copyExpr) {
     llvm::Value *rawAdjustedExn = CallBeginCatch(CGF, Exn, true);
-    Address adjustedExn(CGF.Builder.CreateBitCast(rawAdjustedExn, PtrTy),
+    Address adjustedExn(CGF.Builder.CreatePointerCast(rawAdjustedExn, PtrTy),
                         LLVMCatchTy, caughtExnAlignment);
     LValue Dest = CGF.MakeAddrLValue(ParamAddr, CatchType);
     LValue Src = CGF.MakeAddrLValue(adjustedExn, CatchType);
@@ -4677,7 +4677,7 @@ static void InitCatchParam(CodeGenFunction &CGF,
     CGF.EmitNounwindRuntimeCall(getGetExceptionPtrFn(CGF.CGM), Exn);
 
   // Cast that to the appropriate type.
-  Address adjustedExn(CGF.Builder.CreateBitCast(rawAdjustedExn, PtrTy),
+  Address adjustedExn(CGF.Builder.CreatePointerCast(rawAdjustedExn, PtrTy),
                       LLVMCatchTy, caughtExnAlignment);
 
   // The copy expression is defined in terms of an OpaqueValueExpr.