[CodeGen] Emit destructor calls for non-trivial C structs returned by function calls and loaded from volatile objects

[ahatanak]

Summary

This is the patch I split out of https://reviews.llvm.org/D64464.

The cleanup is pushed in EmitCallExpr and EmitObjCMessageExpr so that the destructor is called to destruct function call and ObjC message returns. I also added test cases for block function calls since the patch in https://reviews.llvm.org/D64464 wasn't handling that case correctly.

rdar://problem/51867864

[ahatanak]

Revert changes I made to llvm that are unrelated to this patch.

[rjmccall]

clang/lib/CodeGen/CGCall.h

367–368

Does llvm::Value* actually guarantee three bits? Presumably on 64-bit platforms, but we do support 32-bit hosts.

Fortunately, I don't actually think there's any reason to be space-conscious in this class; all the values are short-lived. Might as well pull all the fields out into a bit-field or something.

371

I think the "is externally destructed" semantics make more sense — that is, the *default* should be that a destructor needs to get pushed, and maybe specific contexts should suppress that. That will also let you avoid all the ugly code to compute whether destruction is required in a bunch of generic places.

Actually, "externally destructed" is a really problematic idea; we need to come up with a better solution for contexts that need to be careful about destructor ordering like this, and it should probably be based on passing around and deactivating destructors. But that's for later.

[ahatanak]

Address review comments.

• Declare the flags in ReturnValueSlot as bitfields.
• Replace flag RequiresDestruction with flag IsExternallyDestructed and move the pushDestroy call to EmitCall. I audited all the places where ReturnValueSlot is constructed and there were only a few places where IsExternallyDestructed had to be set to true.

[rjmccall]

clang/lib/CodeGen/CGExprAgg.cpp

827

I don't think setExternallyDestructed can be used to communicate outwards like this; the code isn't set up to just do modifications on a single AggValueSlot that's passed around by reference. Instead, the flags are used to communicate downwards to the callees, and the expectation needs to be that callees will push a destructor when they're done initializing unless isExternallyDestructed is set on the dest slot they receive.

[ahatanak]

Fix the way IsExternallyDestructed is used.

[rjmccall]

clang/lib/Sema/SemaExpr.cpp

677

Why only when the l-value is volatile?

5733

You should do this in MaybeBindToTemporary, and then you probably don't need it in most of these other places.

[ahatanak]

Address review comments.

clang/lib/Sema/SemaExpr.cpp

677

I was trying to avoid emitting ExprWithCleanups when it wasn't needed and it seemed that it wasn't needed for non-volatile types. I'm not sure it's important, so I've removed the check for volatile. Also, ExprWithCleanups shouldn't' be emitted when this is in file scope, so I fixed that too.

[rjmccall]

clang/lib/Sema/SemaExpr.cpp

677

Hmm, not sure about this file-scope thing, since the combination of C++ dynamic initializers and statement-expressions means we can have pretty unrestricted code there.

[ahatanak]

clang/lib/Sema/SemaExpr.cpp

677

I should have explained why this was needed, but I wanted to prevent emitting ExprWithCleanups in the following example:

struct A {
  id f0;
};

typedef struct A A;

A g = (A){ .f0 = 0 };

The l-value to r-value conversion happens here because compound literals are l-values. Since g is a global of a non-trivial C struct type, we shouldn't try to push a cleanup and destruct the object.

We don't have to think about the C++ case since the line below checks the type is a non-trivial C type. I didn't think about statement expressions, but they aren't allowed in file scope, so I guess that's not a problem either.

[rjmccall]

clang/lib/Sema/SemaExpr.cpp

677

I would hope that the constant-evaluator here might be smart enough to ignore some elidable temporaries.

[ahatanak]

clang/lib/Sema/SemaExpr.cpp

677

Do you mean the constant-evaluator should evaluate initializers that are ExprWithCleanups to constants in a case like this? It's possible to do so by seeing whether the sub-expression of ExprWithCleanups is constant, but it looks like we also have to set the CleanupInfo::CleanupsHaveSideEffects flag to false when it's a file scope expression so that ConstExprEmitter::VisitExprWithCleanups can constant-fold the ExprWithCleanups initializer.

[rjmccall]

clang/lib/Sema/SemaExpr.cpp

677

In this case, what we're doing is eliding a "temporary" (really an object with wider lifetime, but if the object isn't referenceable, we can compile as-if the object is really temporary) and therefore bypassing the need for a cleanup entirely. I wouldn't expect the AST to change to reflect that this is possible, just the constant evaluator. Basically, it needs to look through ExprWithCleanups; we probably already peephole the LValueToRValue(CompoundLiteralExpr) combination.

We do try to do constant-evaluation on local initializers as well as an optimization, and abstractly that should also work with these constructs.

[ahatanak]

Teach Expr::isConstantInitializer that ExprWithCleanups can be a constant.

[ahatanak]

clang/lib/Sema/SemaExpr.cpp

677

I taught Expr::isConstantInitializer to look through ExprWithCleanups and ConstExprEmitter::VisitExprWithCleanups to ignore whether the expression has side effects. For the latter, I'm assuming we don't have to care about the side effect of the cleanup if the need for a cleanup is elided. This change causes CodeGenFunction::EmitAutoVarInit to emit the initializer as a constant too.

[rjmccall]

Thank, this looks great.

clang/include/clang/Sema/Sema.h

   ExprResult ActOnInstanceMessage(Scope *S,
                                   Expr *Receiver,
                                   Selector Sel,
                                   SourceLocation LBracLoc,
                                   ArrayRef<SourceLocation> SelectorLocs,
                                   SourceLocation RBracLoc,
                                   MultiExprArg Args);
 
+  void ActOnFinishObjCMessageSend(ExprResult Result);
+
   ExprResult BuildObjCBridgedCast(SourceLocation LParenLoc,
                                   ObjCBridgeCastKind Kind,
                                   SourceLocation BridgeKeywordLoc,
                                   TypeSourceInfo *TSInfo,
                                   Expr *SubExpr);
 
   ExprResult ActOnObjCBridgedCast(Scope *S,
                                   SourceLocation LParenLoc,

clang/lib/CodeGen/CGCall.h

 /// FunctionArgList - Type for representing both the decl and type
 /// of parameters to a function. The decl must be either a
 /// ParmVarDecl or ImplicitParamDecl.
 class FunctionArgList : public SmallVector<const VarDecl *, 16> {};
 
 /// ReturnValueSlot - Contains the address where the return value of a
 /// function can be stored, and whether the address is volatile or not.
 class ReturnValueSlot {
-  llvm::PointerIntPair<llvm::Value *, 2, unsigned int> Value;
-  CharUnits Alignment;
+  Address Addr = Address::invalid();
 
   // Return value slot flags
-  enum Flags {
-    IS_VOLATILE = 0x1,
-    IS_UNUSED = 0x2,
-  };
+  unsigned IsVolatile : 1;
+  unsigned IsUnused : 1;
+  unsigned IsExternallyDestructed : 1;
 
 public:
-  ReturnValueSlot() {}
-  ReturnValueSlot(Address Addr, bool IsVolatile, bool IsUnused = false)
-      : Value(Addr.isValid() ? Addr.getPointer() : nullptr,
-              (IsVolatile ? IS_VOLATILE : 0) | (IsUnused ? IS_UNUSED : 0)),
-        Alignment(Addr.isValid() ? Addr.getAlignment() : CharUnits::Zero()) {}
-
-  bool isNull() const { return !getValue().isValid(); }
-
-  bool isVolatile() const { return Value.getInt() & IS_VOLATILE; }
-  Address getValue() const { return Address(Value.getPointer(), Alignment); }
-  bool isUnused() const { return Value.getInt() & IS_UNUSED; }
+  ReturnValueSlot()
+      : IsVolatile(false), IsUnused(false), IsExternallyDestructed(false) {}
+  ReturnValueSlot(Address Addr, bool IsVolatile, bool IsUnused = false,
+                  bool IsExternallyDestructed = false)
+      : Addr(Addr), IsVolatile(IsVolatile), IsUnused(IsUnused),
+        IsExternallyDestructed(IsExternallyDestructed) {}
+
+  bool isNull() const { return !Addr.isValid(); }
+  bool isVolatile() const { return IsVolatile; }
+  Address getValue() const { return Addr; }
+  bool isUnused() const { return IsUnused; }
+  bool isExternallyDestructed() const { return IsExternallyDestructed; }
 };
 
 } // end namespace CodeGen
 } // end namespace clang
 
 #endif

clang/lib/CodeGen/CGCall.cpp

if (Ret.isScalar() && TargetDecl) {
     AllocAlignAttrEmitter.EmitAsAnAssumption(Loc, RetTy, Ret);
   }
 
   // Explicitly call CallLifetimeEnd::Emit just to re-use the code even though
   // we can't use the full cleanup mechanism.
   for (CallLifetimeEnd &LifetimeEnd : CallLifetimeEndAfterCall)
     LifetimeEnd.Emit(*this, /*Flags=*/{});
 
+  if (!ReturnValue.isExternallyDestructed() &&
+      RetTy.isDestructedType() == QualType::DK_nontrivial_c_struct)
+    pushDestroy(QualType::DK_nontrivial_c_struct, Ret.getAggregateAddress(),
+                RetTy);
+
   return Ret;
 }
 
 CGCallee CGCallee::prepareConcreteCallee(CodeGenFunction &CGF) const {
   if (isVirtual()) {
     const CallExpr *CE = getVirtualCallExpr();
     return CGF.CGM.getCXXABI().getVirtualFunctionPointer(
         CGF, getVirtualMethodDecl(), getThisAddress(), getVirtualFunctionType(),

clang/lib/CodeGen/CGClass.cpp

void CodeGenFunction::EmitForwardingCallToLambda(
   // Prepare the return slot.
   const FunctionProtoType *FPT =
     callOperator->getType()->castAs<FunctionProtoType>();
   QualType resultType = FPT->getReturnType();
   ReturnValueSlot returnSlot;
   if (!resultType->isVoidType() &&
       calleeFnInfo.getReturnInfo().getKind() == ABIArgInfo::Indirect &&
       !hasScalarEvaluationKind(calleeFnInfo.getReturnType()))
-    returnSlot = ReturnValueSlot(ReturnValue, resultType.isVolatileQualified());
+    returnSlot = ReturnValueSlot(ReturnValue, resultType.isVolatileQualified(),
+                                 /*IsUnused=*/false, /*IsExternallyDestructed=*/true);
 
   // We don't need to separately arrange the call arguments because
   // the call can't be variadic anyway --- it's impossible to forward
   // variadic arguments.
 
   // Now emit our call.
   auto callee = CGCallee::forDirect(calleePtr, GlobalDecl(callOperator));
   RValue RV = EmitCall(calleeFnInfo, callee, returnSlot, callArgs);

clang/lib/CodeGen/CGExprAgg.cpp

bool AggExprEmitter::TypeRequiresGCollection(QualType T) {
   // Check whether the type has an object member.
   return Record->hasObjectMember();
 }
 
 void AggExprEmitter::withReturnValueSlot(
     const Expr *E, llvm::function_ref<RValue(ReturnValueSlot)> EmitCall) {
   QualType RetTy = E->getType();
   bool RequiresDestruction =
-      Dest.isIgnored() &&
+      !Dest.isExternallyDestructed() &&
       RetTy.isDestructedType() == QualType::DK_nontrivial_c_struct;
 
   // If it makes no observable difference, save a memcpy + temporary.
   //
   // We need to always provide our own temporary if destruction is required.
   // Otherwise, EmitCall will emit its own, notice that it's "unused", and end
   // its lifetime before we have the chance to emit a proper destructor call.
   bool UseTemp = Dest.isPotentiallyAliased() || Dest.requiresGCollection() ||
if (LifetimeSizePtr) {
 
       CGF.pushFullExprCleanup<CodeGenFunction::CallLifetimeEnd>(
           NormalEHLifetimeMarker, RetAllocaAddr, LifetimeSizePtr);
       LifetimeEndBlock = CGF.EHStack.stable_begin();
     }
   }
 
   RValue Src =
-      EmitCall(ReturnValueSlot(RetAddr, Dest.isVolatile(), IsResultUnused));
-
-  if (RequiresDestruction)
-    CGF.pushDestroy(RetTy.isDestructedType(), Src.getAggregateAddress(), RetTy);
+      EmitCall(ReturnValueSlot(RetAddr, Dest.isVolatile(), IsResultUnused,
+                               Dest.isExternallyDestructed()));
 
   if (!UseTemp)
     return;
 
   assert(Dest.getPointer() != Src.getAggregatePointer());
   EmitFinalDestCopy(E->getType(), Src);
 
   if (!RequiresDestruction && LifetimeStartInst) {
void AggExprEmitter::VisitCastExpr(CastExpr *E) {
   }
   case CK_AddressSpaceConversion:
      return Visit(E->getSubExpr());
 
   case CK_LValueToRValue:
     // If we're loading from a volatile type, force the destination
     // into existence.
     if (E->getSubExpr()->getType().isVolatileQualified()) {
+      bool Destruct =
+          !Dest.isExternallyDestructed() &&
+          E->getType().isDestructedType() == QualType::DK_nontrivial_c_struct;
+      if (Destruct)
+        Dest.setExternallyDestructed();
       EnsureDest(E->getType());
-      return Visit(E->getSubExpr());
+      Visit(E->getSubExpr());
+
+      if (Destruct)
+        CGF.pushDestroy(QualType::DK_nontrivial_c_struct, Dest.getAddress(),
+                        E->getType());
+
+      return;
     }
 
     LLVM_FALLTHROUGH;
 
 
   case CK_NoOp:
   case CK_UserDefinedConversion:
   case CK_ConstructorConversion:
     assert(CGF.getContext().hasSameUnqualifiedType(E->getSubExpr()->getType(),

clang/lib/CodeGen/CGVTables.cpp

#endif
   QualType ResultType = CGM.getCXXABI().HasThisReturn(CurGD)
                             ? ThisType
                             : CGM.getCXXABI().hasMostDerivedReturn(CurGD)
                                   ? CGM.getContext().VoidPtrTy
                                   : FPT->getReturnType();
   ReturnValueSlot Slot;
   if (!ResultType->isVoidType() &&
       CurFnInfo->getReturnInfo().getKind() == ABIArgInfo::Indirect)
-    Slot = ReturnValueSlot(ReturnValue, ResultType.isVolatileQualified());
+    Slot = ReturnValueSlot(ReturnValue, ResultType.isVolatileQualified(),
+                           /*IsUnused=*/false, /*IsExternallyDestructed=*/true);
 
   // Now emit our call.
   llvm::CallBase *CallOrInvoke;
   RValue RV = EmitCall(*CurFnInfo, CGCallee::forDirect(Callee, CurGD), Slot,
                        CallArgs, &CallOrInvoke);
 
   // Consider return adjustment if we have ThunkInfo.
   if (Thunk && !Thunk->Return.isEmpty())

clang/lib/Parse/ParseObjc.cpp

Parser::ParseObjCMessageExpressionBody(SourceLocation LBracLoc,
 
   unsigned nKeys = KeyIdents.size();
   if (nKeys == 0) {
     KeyIdents.push_back(selIdent);
     KeyLocs.push_back(Loc);
   }
   Selector Sel = PP.getSelectorTable().getSelector(nKeys, &KeyIdents[0]);
 
+  ExprResult Result;
   if (SuperLoc.isValid())
-    return Actions.ActOnSuperMessage(getCurScope(), SuperLoc, Sel,
+    Result = Actions.ActOnSuperMessage(getCurScope(), SuperLoc, Sel,
                                        LBracLoc, KeyLocs, RBracLoc, KeyExprs);
   else if (ReceiverType)
-    return Actions.ActOnClassMessage(getCurScope(), ReceiverType, Sel,
-                                     LBracLoc, KeyLocs, RBracLoc, KeyExprs);
-  return Actions.ActOnInstanceMessage(getCurScope(), ReceiverExpr, Sel,
+    Result = Actions.ActOnClassMessage(getCurScope(), ReceiverType, Sel,
                                        LBracLoc, KeyLocs, RBracLoc, KeyExprs);
+  else
+    Result = Actions.ActOnInstanceMessage(getCurScope(), ReceiverExpr, Sel,
+                                          LBracLoc, KeyLocs, RBracLoc,
+                                          KeyExprs);
+  Actions.ActOnFinishObjCMessageSend(Result);
+  return Result;
 }
 
 ExprResult Parser::ParseObjCStringLiteral(SourceLocation AtLoc) {
   ExprResult Res(ParseStringLiteralExpression());
   if (Res.isInvalid()) return Res;
 
   // @"foo" @"bar" is a valid concatenated string.  Eat any subsequent string
   // expressions.  At this point, we know that the only valid thing that starts

clang/lib/Sema/SemaExpr.cpp

if (Res.isInvalid())
     return Res;
   E = Res.get();
 
   // Loading a __weak object implicitly retains the value, so we need a cleanup to
   // balance that.
   if (E->getType().getObjCLifetime() == Qualifiers::OCL_Weak)
     Cleanup.setExprNeedsCleanups(true);
 
+  if (E->getType().isVolatileQualified() &&
+      E->getType().isDestructedType() == QualType::DK_nontrivial_c_struct)
+    Cleanup.setExprNeedsCleanups(true);
+
   // C++ [conv.lval]p3:
   //   If T is cv std::nullptr_t, the result is a null pointer constant.
   CastKind CK = T->isNullPtrType() ? CK_NullToPointer : CK_LValueToRValue;
   Res = ImplicitCastExpr::Create(Context, T, CK, E, nullptr, VK_RValue);
 
   // C11 6.3.2.1p2:
   //   ... if the lvalue has atomic type, the value has the non-atomic version
   //   of the type of the lvalue ...
if (ULE->hasExplicitTemplateArgs() &&
         ULE->decls_begin() == ULE->decls_end()) {
       Diag(Fn->getExprLoc(), getLangOpts().CPlusPlus2a
                                  ? diag::warn_cxx17_compat_adl_only_template_id
                                  : diag::ext_adl_only_template_id)
           << ULE->getName();
     }
   }
 
+  if (Call.get()->getType().isDestructedType() ==
+      QualType::DK_nontrivial_c_struct)
+    Cleanup.setExprNeedsCleanups(true);
+
   return Call;
 }
 
 /// BuildCallExpr - Handle a call to Fn with the specified array of arguments.
 /// This provides the location of the left/right parens and a list of comma
 /// locations.
 ExprResult Sema::BuildCallExpr(Scope *Scope, Expr *Fn, SourceLocation LParenLoc,
                                MultiExprArg ArgExprs, SourceLocation RParenLoc,

clang/lib/Sema/SemaExprObjC.cpp

if (Sel == RespondsToSelectorSel)
     RemoveSelectorFromWarningCache(*this, Args[0]);
 
   return BuildInstanceMessage(Receiver, Receiver->getType(),
                               /*SuperLoc=*/SourceLocation(), Sel,
                               /*Method=*/nullptr, LBracLoc, SelectorLocs,
                               RBracLoc, Args);
 }
 
+void Sema::ActOnFinishObjCMessageSend(ExprResult Result) {
+  if (!Result.isInvalid() &&
+      Result.get()->getType().isDestructedType() ==
+      QualType::DK_nontrivial_c_struct)
+    Cleanup.setExprNeedsCleanups(true);
+}
+
 enum ARCConversionTypeClass {
   /// int, void, struct A
   ACTC_none,
 
   /// id, void (^)()
   ACTC_retainable,
 
   /// id*, id***, void (^*)(),

clang/test/CodeGenObjC/arc.m

struct AggDtor {
   char cs[40];
   id x;
 };
 
 struct AggDtor getAggDtor(void);
 
 // CHECK-LABEL: define void @test71
 void test71(void) {
-  // FIXME: It would be nice if the __destructor_8_s40 for the first call (and
-  // the following lifetime.end) came before the second call.
-  //
   // CHECK: %[[T:[^ ]+]] = bitcast %struct.AggDtor* %[[TMP1:[^ ]+]] to i8*
   // CHECK: call void @llvm.lifetime.start.p0i8({{[^,]+}}, i8* %[[T]])
   // CHECK: call void @getAggDtor(%struct.AggDtor* sret %[[TMP1]])
+  // CHECK: %[[T:[^ ]+]] = bitcast %struct.AggDtor* %[[TMP1]] to i8**
+  // CHECK: call void @__destructor_8_s40(i8** %[[T]])
+  // CHECK: %[[T:[^ ]+]] = bitcast %struct.AggDtor* %[[TMP1:[^ ]+]] to i8*
+  // CHECK: call void @llvm.lifetime.end.p0i8({{[^,]+}}, i8* %[[T]])
   // CHECK: %[[T:[^ ]+]] = bitcast %struct.AggDtor* %[[TMP2:[^ ]+]] to i8*
   // CHECK: call void @llvm.lifetime.start.p0i8({{[^,]+}}, i8* %[[T]])
   // CHECK: call void @getAggDtor(%struct.AggDtor* sret %[[TMP2]])
   // CHECK: %[[T:[^ ]+]] = bitcast %struct.AggDtor* %[[TMP2]] to i8**
   // CHECK: call void @__destructor_8_s40(i8** %[[T]])
   // CHECK: %[[T:[^ ]+]] = bitcast %struct.AggDtor* %[[TMP2:[^ ]+]] to i8*
   // CHECK: call void @llvm.lifetime.end.p0i8({{[^,]+}}, i8* %[[T]])
-  // CHECK: %[[T:[^ ]+]] = bitcast %struct.AggDtor* %[[TMP1]] to i8**
-  // CHECK: call void @__destructor_8_s40(i8** %[[T]])
-  // CHECK: %[[T:[^ ]+]] = bitcast %struct.AggDtor* %[[TMP1:[^ ]+]] to i8*
-  // CHECK: call void @llvm.lifetime.end.p0i8({{[^,]+}}, i8* %[[T]])
   getAggDtor();
   getAggDtor();
 }
 
 // ARC-ALIEN: attributes [[NLB]] = { nonlazybind }
 // ARC-NATIVE: attributes [[NLB]] = { nonlazybind }
 // CHECK: attributes [[NUW]] = { nounwind }

clang/test/CodeGenObjC/strong-in-c-struct.m

 #ifdef USESTRUCT
 
 StrongSmall getStrongSmall(void);
 StrongOuter getStrongOuter(void);
 StrongOuter2 getStrongOuter2(void);
 void calleeStrongSmall(StrongSmall);
 void func(Strong *);
 
+@interface C
+-(StrongSmall)getStrongSmall;
++(StrongSmall)getStrongSmallClass;
+@end
+
+id g0;
+
 // CHECK: %[[STRUCT_STRONGOUTER:.*]] = type { %[[STRUCT_STRONG:.*]], i8*, double }
 // CHECK: %[[STRUCT_STRONG]] = type { %[[STRUCT_TRIVIAL:.*]], i8* }
 // CHECK: %[[STRUCT_TRIVIAL]] = type { [4 x i32] }
 // CHECK: %[[STRUCT_BLOCK_BYREF_T:.*]] = type { i8*, %[[STRUCT_BLOCK_BYREF_T]]*, i32, i32, i8*, i8*, i8*, %[[STRUCT_STRONGOUTER]] }
 // CHECK: %[[STRUCT_STRONGSMALL:.*]] = type { i32, i8* }
 // CHECK: %[[STRUCT_STRONGBLOCK:.*]] = type { void ()* }
 // CHECK: %[[STRUCT_BITFIELD1:.*]] = type { i8, i8, i8*, i32, i8*, [3 x i32], i8*, double, i8, i8 }
 

 // CHECK: %[[V1:.*]] = bitcast %[[STRUCT_STRONGSMALL]]* %[[COERCE]] to i8**
 // CHECK: call void @__destructor_8_s8(i8** %[[V1]])
 // CHECK: ret void
 
 void test_destructor_ignored_result(void) {
   getStrongSmall();
 }
 
+// CHECK: define void @test_destructor_ignored_result2(%{{.*}}* %[[C:.*]])
+// CHECK: %[[TMP:.*]] = alloca %[[STRUCT_STRONGSMALL]], align 8
+// CHECK: %[[CALL:.*]] = call [2 x i64]{{.*}}@objc_msgSend
+// CHECK: %[[V5:.*]] = bitcast %[[STRUCT_STRONGSMALL]]* %[[TMP]] to [2 x i64]*
+// CHECK: store [2 x i64] %[[CALL]], [2 x i64]* %[[V5]], align 8
+// CHECK: %[[V6:.*]] = bitcast %[[STRUCT_STRONGSMALL]]* %[[TMP]] to i8**
+// CHECK: call void @__destructor_8_s8(i8** %[[V6]])
+
+void test_destructor_ignored_result2(C *c) {
+  [c getStrongSmall];
+}
+
 // CHECK: define void @test_copy_constructor_StrongBlock(
 // CHECK: call void @__copy_constructor_8_8_sb0(
 // CHECK: call void @__destructor_8_sb0(
 // CHECK: ret void
 
 // CHECK: define linkonce_odr hidden void @__copy_constructor_8_8_sb0(i8** %[[DST:.*]], i8** %[[SRC:.*]])
 // CHECK: %[[DST_ADDR:.*]] = alloca i8**, align 8
 // CHECK: %[[SRC_ADDR:.*]] = alloca i8**, align 8

 // CHECK: ret void
 
 void test_copy_assignment_StrongBlock(StrongBlock *d, StrongBlock *s) {
   *d = *s;
 }
 
 // CHECK: define void @test_copy_constructor_StrongVolatile0(
 // CHECK: call void @__copy_constructor_8_8_t0w4_sv8(
+// CHECK-NOT: call
 // CHECK: call void @__destructor_8_sv8(
+// CHECK-NOT: call
 
 // CHECK: define linkonce_odr hidden void @__copy_constructor_8_8_t0w4_sv8(
 // CHECK: %[[V8:.*]] = load volatile i8*, i8** %{{.*}}, align 8
 // CHECK: %[[V9:.*]] = call i8* @llvm.objc.retain(i8* %[[V8]])
 // CHECK: store volatile i8* %[[V9]], i8** %{{.*}}, align 8
 
 void test_copy_constructor_StrongVolatile0(StrongVolatile *s) {
   StrongVolatile t = *s;

 // CHECK: %[[V13:.*]] = bitcast i8** %[[ADDR_CUR1]] to i32*
 // CHECK: %[[V14:.*]] = load volatile i32, i32* %[[V13]], align 4
 // CHECK: store volatile i32 %[[V14]], i32* %[[V12]], align 4
 
 void test_copy_constructor_VolatileArray(VolatileArray *a) {
   VolatileArray t = *a;
 }
 
+// CHECK: define void @test_member_access(
+// CHECK: %[[TMP:.*]] = alloca %[[STRUCT_STRONGSMALL]],
+// CHECK: %[[V3:.*]] = bitcast %[[STRUCT_STRONGSMALL]]* %[[TMP]] to i8**
+// CHECK: call void @__destructor_8_s8(i8** %[[V3]])
+// CHECK: call void @func(
+
+void test_member_access(void) {
+  g0 = getStrongSmall().f1;
+  func(0);
+}
+
+// CHECK: define void @test_member_access2(%{{.*}}* %[[C:.*]])
+// CHECK: %[[COERCE:.*]] = alloca %[[STRUCT_STRONGSMALL]], align 8
+// CHECK: %[[V8:.*]] = bitcast %[[STRUCT_STRONGSMALL]]* %[[COERCE]] to i8**
+// CHECK: call void @__destructor_8_s8(i8** %[[V8]])
+// CHECK: call void @func(
+
+void test_member_access2(C *c) {
+  g0 = [c getStrongSmall].f1;
+  func(0);
+}
+
+// CHECK: define void @test_member_access3(
+// CHECK: %[[COERCE:.*]] = alloca %[[STRUCT_STRONGSMALL]], align 8
+// CHECK: %[[V8:.*]] = bitcast %[[STRUCT_STRONGSMALL]]* %[[COERCE]] to i8**
+// CHECK: call void @__destructor_8_s8(i8** %[[V8]])
+// CHECK: call void @func(
+
+void test_member_access3(void) {
+  g0 = [C getStrongSmallClass].f1;
+  func(0);
+}
+
+// CHECK: define void @test_member_access4()
+// CHECK: %[[COERCE:.*]] = alloca %[[STRUCT_STRONGSMALL]], align 8
+// CHECK: %[[V5:.*]] = bitcast %[[STRUCT_STRONGSMALL]]* %[[COERCE]] to i8**
+// CHECK: call void @__destructor_8_s8(i8** %[[V5]])
+// CHECK: call void @func(
+
+void test_member_access4(void) {
+  g0 = ^{ StrongSmall s; return s; }().f1;
+  func(0);
+}
+
+// CHECK: define void @test_volatile_variable_reference(
+// CHECK: %[[AGG_TMP_ENSURED:.*]] = alloca %[[STRUCT_STRONGSMALL]],
+// CHECK: %[[V1:.*]] = bitcast %[[STRUCT_STRONGSMALL]]* %[[AGG_TMP_ENSURED]] to i8**
+// CHECK: %[[V2:.*]] = bitcast %[[STRUCT_STRONGSMALL]]* %{{.*}} to i8**
+// CHECK: call void @__copy_constructor_8_8_tv0w32_sv8(i8** %[[V1]], i8** %[[V2]])
+// CHECK: %[[V3:.*]] = bitcast %[[STRUCT_STRONGSMALL]]* %[[AGG_TMP_ENSURED]] to i8**
+// CHECK: call void @__destructor_8_s8(i8** %[[V3]])
+// CHECK: call void @func(
+
+void test_volatile_variable_reference(volatile StrongSmall *a) {
+  (void)*a;
+  func(0);
+}
+
 #endif /* USESTRUCT */