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When performing a derived-to-base cast on the right-hand side of the 

synthesized move assignment within an implicitly-defined move
assignment operator, be sure to treat the derived-to-base cast as an
xvalue (rather than an lvalue). Otherwise, we'll end up getting the
wrong constructor.

Optimize a direct call to a trivial move assignment operator to an
aggregate copy, as we do for trivial copy assignment operators, and
update the the assertion in CodeGenFunction::EmitAggregateCopy() to
cope with this optimization.

Fixes PR10860.

llvm-svn: 139143
This commit is contained in:
Douglas Gregor 2011-09-06 16:26:56 +00:00
parent a098436b32
commit 146b8e9a58
4 changed files with 32 additions and 14 deletions
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4
clang/lib/CodeGen/CGExprAgg.cpp
View File

@ -1069,7 +1069,9 @@ void CodeGenFunction::EmitAggregateCopy(llvm::Value *DestPtr,
if (const RecordType *RT = Ty->getAs<RecordType>()) {
CXXRecordDecl *Record = cast<CXXRecordDecl>(RT->getDecl());
assert((Record->hasTrivialCopyConstructor() ||
Record->hasTrivialCopyAssignment()) &&
Record->hasTrivialCopyAssignment() ||
Record->hasTrivialMoveConstructor() ||
Record->hasTrivialMoveAssignment()) &&
"Trying to aggregate-copy a type without a trivial copy "
"constructor or assignment operator");
// Ignore empty classes in C++.

16
clang/lib/CodeGen/CGExprCXX.cpp
View File

@ -334,16 +334,12 @@ CodeGenFunction::EmitCXXOperatorMemberCallExpr(const CXXOperatorCallExpr *E,
LValue LV = EmitLValue(E->getArg(0));
llvm::Value *This = LV.getAddress();
if (MD->isCopyAssignmentOperator()) {
const CXXRecordDecl *ClassDecl = cast<CXXRecordDecl>(MD->getDeclContext());
if (ClassDecl->hasTrivialCopyAssignment()) {
assert(!ClassDecl->hasUserDeclaredCopyAssignment() &&
"EmitCXXOperatorMemberCallExpr - user declared copy assignment");
llvm::Value *Src = EmitLValue(E->getArg(1)).getAddress();
QualType Ty = E->getType();
EmitAggregateCopy(This, Src, Ty);
return RValue::get(This);
}
if ((MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator()) &&
MD->isTrivial()) {
llvm::Value *Src = EmitLValue(E->getArg(1)).getAddress();
QualType Ty = E->getType();
EmitAggregateCopy(This, Src, Ty);
return RValue::get(This);
}
llvm::Value *Callee = EmitCXXOperatorMemberCallee(E, MD, This);

2
clang/lib/Sema/SemaDeclCXX.cpp
View File

@ -7847,7 +7847,7 @@ void Sema::DefineImplicitMoveAssignment(SourceLocation CurrentLocation,
// appropriately-qualified base type.
Expr *From = OtherRef;
From = ImpCastExprToType(From, BaseType, CK_UncheckedDerivedToBase,
VK_RValue, &BasePath).take();
VK_XValue, &BasePath).take();
// Dereference "this".
ExprResult To = CreateBuiltinUnaryOp(Loc, UO_Deref, This);

24
clang/test/CXX/special/class.copy/implicit-move-def.cpp
View File

@ -61,9 +61,25 @@ struct I {
unsigned var[1];
};
// CHECK: define void @_Z1hv() nounwind {
void h() {
I i;
// CHECK: call void @llvm.memcpy.
i = I();
// CHECK-NEXT: ret void
}
// PR10860
struct Empty { };
struct VirtualWithEmptyBase : Empty {
virtual void f();
};
// CHECK: define void @_Z25move_VirtualWithEmptyBaseR20VirtualWithEmptyBaseS0_
void move_VirtualWithEmptyBase(VirtualWithEmptyBase &x, VirtualWithEmptyBase &y) {
// CHECK: call {{.*}} @_ZN20VirtualWithEmptyBaseaSEOS_
x = static_cast<VirtualWithEmptyBase&&>(y);
// CHECK-NEXT: ret void
}
// move assignment ops
@ -76,8 +92,12 @@ void h() {
// CHECK-ASSIGN: br i1
// CHECK-ASSIGN: call {{.*}} @_ZN1AaSEOS_
// CHECK-ASSIGN: define linkonce_odr {{.*}} @_ZN1IaSEOS_
// call void @llvm.memcpy.
// VirtualWithEmptyBase move assignment operatpr
// CHECK-ASSIGN: define linkonce_odr {{.*}} @_ZN20VirtualWithEmptyBaseaSEOS_
// CHECK-ASSIGN: store
// CHECK-ASSIGN-NEXT: store
// CHECK-NOT: call
// CHECK: ret
// CHECK-ASSIGN: define linkonce_odr {{.*}} @_ZN1CaSEOS_
// CHECK-ASSIGN: call {{.*}} @_ZN1AaSEOS_