[PR40778] Preserve addr space in Derived to Base cast

[Anastasia]

Summary

The address space for the Base class pointer when up-casting from Derived should be taken from the Derived class pointer.

[rjmccall]

lib/Sema/SemaExpr.cpp

2674

This path (when the object is a gl-value) also needs an address-space qualifier, so you should probably add it above and then just add a pointer in the pointer case.

[Anastasia]

Moved adding address space to DestType earlier to cover pointer and non-pointer case.

[Anastasia]

lib/Sema/SemaExpr.cpp

2674

I updated this but I haven't really found any test case that would fail. I guess because casting non-pointer types in different address spaces works fine...

For example the IR is generated correctly with or without the fix.

1 struct S {
2    volatile int a;
3 }; 
4 
5 __global S g;
6 
7 void foo(){
8 g.a; 
9 }

However, I still think it's indeed good to add the address space in both cases for consistency.

[rjmccall]

lib/Sema/SemaExpr.cpp

2666

Please do a getAs<PointerType>() into a local and then use that here and below.

[Anastasia]

Use common pointer type.

[rjmccall]

lib/Sema/SemaExpr.cpp

2671

And here.

[Anastasia]

lib/Sema/SemaExpr.cpp

2671

Oh, yes... thanks!

[rjmccall]

Thanks, LGTM.

[Anastasia]

Committed in r355606.

lib/CodeGen/CGClass.cpp

if (VBase && Derived->hasAttr<FinalAttr>()) {
     const ASTRecordLayout &layout = getContext().getASTRecordLayout(Derived);
     CharUnits vBaseOffset = layout.getVBaseClassOffset(VBase);
     NonVirtualOffset += vBaseOffset;
     VBase = nullptr; // we no longer have a virtual step
   }
 
   // Get the base pointer type.
   llvm::Type *BasePtrTy =
-    ConvertType((PathEnd[-1])->getType())->getPointerTo();
+      ConvertType((PathEnd[-1])->getType())
+          ->getPointerTo(Value.getType()->getPointerAddressSpace());
 
   QualType DerivedTy = getContext().getRecordType(Derived);
   CharUnits DerivedAlign = CGM.getClassPointerAlignment(Derived);
 
   // If the static offset is zero and we don't have a virtual step,
   // just do a bitcast; null checks are unnecessary.
   if (NonVirtualOffset.isZero() && !VBase) {
     if (sanitizePerformTypeCheck()) {

lib/Sema/SemaExpr.cpp

Sema::PerformObjectMemberConversion(Expr *From,
 
   QualType DestRecordType;
   QualType DestType;
   QualType FromRecordType;
   QualType FromType = From->getType();
   bool PointerConversions = false;
   if (isa<FieldDecl>(Member)) {
     DestRecordType = Context.getCanonicalType(Context.getTypeDeclType(RD));
+    auto FromPtrType = FromType->getAs<PointerType>();
+    DestRecordType = Context.getAddrSpaceQualType(
+        DestRecordType, FromPtrType
+                            ? FromType->getPointeeType().getAddressSpace()
+                            : FromType.getAddressSpace());
 
-    if (FromType->getAs<PointerType>()) {
+    if (FromPtrType) {
       DestType = Context.getPointerType(DestRecordType);
-      FromRecordType = FromType->getPointeeType();
+      FromRecordType = FromPtrType->getPointeeType();
       PointerConversions = true;
     } else {
       DestType = DestRecordType;
       FromRecordType = FromType;
     }
   } else if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Member)) {
     if (Method->isStatic())
       return From;
 
     DestType = Method->getThisType();
     DestRecordType = DestType->getPointeeType();

test/CodeGenOpenCLCXX/addrspace-derived-base.cl

+// RUN: %clang_cc1 %s -triple spir -cl-std=c++ -emit-llvm -O0 -o - | FileCheck %s
+
+struct B {
+  int mb;
+};
+
+class D : public B {
+public:
+  int getmb() { return mb; }
+};
+
+void foo() {
+  D d;
+  //CHECK: addrspacecast %class.D* %d to %class.D addrspace(4)*
+  //CHECK: call i32 @_ZNU3AS41D5getmbEv(%class.D addrspace(4)*
+  d.getmb();
+}
+
+//Derived and Base are in the same address space.
+
+//CHECK: define linkonce_odr i32 @_ZNU3AS41D5getmbEv(%class.D addrspace(4)* %this)
+//CHECK: bitcast %class.D addrspace(4)* %this1 to %struct.B addrspace(4)*