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Initialize vtorDisp in class constructors and destructors 

Reviewed at http://llvm-reviews.chandlerc.com/D1867

llvm-svn: 192312
This commit is contained in:
Timur Iskhodzhanov 2013-10-09 18:16:58 +00:00
parent 85cc66d85e
commit b648732230
4 changed files with 160 additions and 7 deletions
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6
clang/lib/CodeGen/CGCXXABI.h
View File

@ -234,6 +234,12 @@ public:
virtual llvm::BasicBlock *EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,
const CXXRecordDecl *RD);
/// Emit the code to initialize hidden members required
/// to handle virtual inheritance, if needed by the ABI.
virtual void
initializeHiddenVirtualInheritanceMembers(CodeGenFunction &CGF,
const CXXRecordDecl *RD) {}
/// Emit constructor variants required by this ABI.
virtual void EmitCXXConstructors(const CXXConstructorDecl *D) = 0;

3
clang/lib/CodeGen/CGClass.cpp
View File

@ -1992,6 +1992,9 @@ void CodeGenFunction::InitializeVTablePointers(const CXXRecordDecl *RD) {
/*NearestVBase=*/0,
/*OffsetFromNearestVBase=*/CharUnits::Zero(),
/*BaseIsNonVirtualPrimaryBase=*/false, RD, VBases);
if (RD->getNumVBases())
CGM.getCXXABI().initializeHiddenVirtualInheritanceMembers(*this, RD);
}
llvm::Value *CodeGenFunction::GetVTablePtr(llvm::Value *This,

58
clang/lib/CodeGen/MicrosoftCXXABI.cpp
View File

@ -67,6 +67,9 @@ public:
llvm::BasicBlock *EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,
const CXXRecordDecl *RD);
void initializeHiddenVirtualInheritanceMembers(CodeGenFunction &CGF,
const CXXRecordDecl *RD);
void EmitCXXConstructors(const CXXConstructorDecl *D);
// Background on MSVC destructors
@ -456,6 +459,61 @@ MicrosoftCXXABI::EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,
return SkipVbaseCtorsBB;
}
void MicrosoftCXXABI::initializeHiddenVirtualInheritanceMembers(
CodeGenFunction &CGF, const CXXRecordDecl *RD) {
// In most cases, an override for a vbase virtual method can adjust
// the "this" parameter by applying a constant offset.
// However, this is not enough while a constructor or a destructor of some
// class X is being executed if all the following conditions are met:
// - X has virtual bases, (1)
// - X overrides a virtual method M of a vbase Y, (2)
// - X itself is a vbase of the most derived class.
//
// If (1) and (2) are true, the vtorDisp for vbase Y is a hidden member of X
// which holds the extra amount of "this" adjustment we must do when we use
// the X vftables (i.e. during X ctor or dtor).
// Outside the ctors and dtors, the values of vtorDisps are zero.
const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD);
typedef ASTRecordLayout::VBaseOffsetsMapTy VBOffsets;
const VBOffsets &VBaseMap = Layout.getVBaseOffsetsMap();
CGBuilderTy &Builder = CGF.Builder;
unsigned AS =
cast<llvm::PointerType>(getThisValue(CGF)->getType())->getAddressSpace();
llvm::Value *Int8This = 0; // Initialize lazily.
for (VBOffsets::const_iterator I = VBaseMap.begin(), E = VBaseMap.end();
I != E; ++I) {
if (!I->second.hasVtorDisp())
continue;
llvm::Value *VBaseOffset = CGM.getCXXABI().GetVirtualBaseClassOffset(
CGF, getThisValue(CGF), RD, I->first);
// FIXME: it doesn't look right that we SExt in GetVirtualBaseClassOffset()
// just to Trunc back immediately.
VBaseOffset = Builder.CreateTruncOrBitCast(VBaseOffset, CGF.Int32Ty);
uint64_t ConstantVBaseOffset =
Layout.getVBaseClassOffset(I->first).getQuantity();
// vtorDisp_for_vbase = vbptr[vbase_idx] - offsetof(RD, vbase).
llvm::Value *VtorDispValue = Builder.CreateSub(
VBaseOffset, llvm::ConstantInt::get(CGM.Int32Ty, ConstantVBaseOffset),
"vtordisp.value");
if (!Int8This)
Int8This = Builder.CreateBitCast(getThisValue(CGF),
CGF.Int8Ty->getPointerTo(AS));
llvm::Value *VtorDispPtr = Builder.CreateInBoundsGEP(Int8This, VBaseOffset);
// vtorDisp is always the 32-bits before the vbase in the class layout.
VtorDispPtr = Builder.CreateConstGEP1_32(VtorDispPtr, -4);
VtorDispPtr = Builder.CreateBitCast(
VtorDispPtr, CGF.Int32Ty->getPointerTo(AS), "vtordisp.ptr");
Builder.CreateStore(VtorDispValue, VtorDispPtr);
}
}
void MicrosoftCXXABI::EmitCXXConstructors(const CXXConstructorDecl *D) {
// There's only one constructor type in this ABI.
CGM.EmitGlobal(GlobalDecl(D, Ctor_Complete));

100
clang/test/CodeGenCXX/microsoft-abi-virtual-inheritance.cpp
View File

@ -1,6 +1,10 @@
// RUN: %clang_cc1 %s -fno-rtti -cxx-abi microsoft -triple=i386-pc-win32 -emit-llvm -o - | FileCheck %s
// For now, just make sure x86_64 doesn't crash.
// RUN: %clang_cc1 %s -fno-rtti -cxx-abi microsoft -triple=x86_64-pc-win32 -emit-llvm -o %t
struct VBase {
virtual ~VBase();
virtual void foo();
virtual void bar();
int field;
@ -8,27 +12,74 @@ struct VBase {
struct B : virtual VBase {
B();
virtual ~B();
virtual void foo();
virtual void bar();
};
B::B() {
// CHECK: @"\01??0B@@QAE@XZ"
// CHECK-LABEL: define x86_thiscallcc %struct.B* @"\01??0B@@QAE@XZ"
// CHECK: %[[THIS:.*]] = load %struct.B**
// CHECK: br i1 %{{.*}}, label %[[INIT_VBASES:.*]], label %[[SKIP_VBASES:.*]]
// Don't check the INIT_VBASES case as it's covered by the ctor tests.
// CHECK: %[[SKIP_VBASES]]
// CHECK: %[[THIS_i8:.*]] = bitcast %struct.B* %[[THIS]] to i8*
// CHECK: %[[VBPTR:.*]] = getelementptr inbounds i8* %[[THIS_i8]], i32 0
// ...
// CHECK: %[[THIS_i8:.*]] = bitcast %struct.B* %[[THIS]] to i8*
// CHECK: %[[VFPTR_i8:.*]] = getelementptr inbounds i8* %[[THIS_i8]], i32 %{{.*}}
// CHECK: %[[VFPTR:.*]] = bitcast i8* %[[VFPTR_i8]] to [2 x i8*]**
// CHECK: store [2 x i8*]* @"\01??_7B@@6B@", [2 x i8*]** %[[VFPTR]]
// FIXME: Should initialize the vtorDisp here.
// CHECK: %[[VFPTR:.*]] = bitcast i8* %[[VFPTR_i8]] to [3 x i8*]**
// CHECK: store [3 x i8*]* @"\01??_7B@@6B@", [3 x i8*]** %[[VFPTR]]
// Initialize vtorDisp:
// CHECK: %[[THIS_i8:.*]] = bitcast %struct.B* %[[THIS]] to i8*
// CHECK: %[[VBPTR:.*]] = getelementptr inbounds i8* %[[THIS_i8]], i32 0
// ...
// CHECK: %[[VBASE_OFFSET:.*]] = add nsw i32 0, %{{.*}}
// CHECK: %[[VTORDISP_VAL:.*]] = sub i32 %[[VBASE_OFFSET]], 8
// CHECK: %[[THIS_i8:.*]] = bitcast %struct.B* %[[THIS]] to i8*
// CHECK: %[[VBASE_i8:.*]] = getelementptr inbounds i8* %[[THIS_i8]], i32 %[[VBASE_OFFSET]]
// CHECK: %[[VTORDISP_i8:.*]] = getelementptr i8* %[[VBASE_i8]], i32 -4
// CHECK: %[[VTORDISP_PTR:.*]] = bitcast i8* %[[VTORDISP_i8]] to i32*
// CHECK: store i32 %[[VTORDISP_VAL]], i32* %[[VTORDISP_PTR]]
// CHECK: ret
}
B::~B() {
// CHECK-LABEL: define x86_thiscallcc void @"\01??1B@@UAE@XZ"
// CHECK: %[[THIS:.*]] = load %struct.B**
// Restore the vfptr that could have been changed by a subclass.
// CHECK: %[[THIS_i8:.*]] = bitcast %struct.B* %[[THIS]] to i8*
// CHECK: %[[VBPTR:.*]] = getelementptr inbounds i8* %[[THIS_i8]], i32 0
// ...
// CHECK: %[[THIS_i8:.*]] = bitcast %struct.B* %[[THIS]] to i8*
// CHECK: %[[VFPTR_i8:.*]] = getelementptr inbounds i8* %[[THIS_i8]], i32 %{{.*}}
// CHECK: %[[VFPTR:.*]] = bitcast i8* %[[VFPTR_i8]] to [3 x i8*]**
// CHECK: store [3 x i8*]* @"\01??_7B@@6B@", [3 x i8*]** %[[VFPTR]]
// Initialize vtorDisp:
// CHECK: %[[THIS_i8:.*]] = bitcast %struct.B* %[[THIS]] to i8*
// CHECK: %[[VBPTR:.*]] = getelementptr inbounds i8* %[[THIS_i8]], i32 0
// ...
// CHECK: %[[VBASE_OFFSET:.*]] = add nsw i32 0, %{{.*}}
// CHECK: %[[VTORDISP_VAL:.*]] = sub i32 %[[VBASE_OFFSET]], 8
// CHECK: %[[THIS_i8:.*]] = bitcast %struct.B* %[[THIS]] to i8*
// CHECK: %[[VBASE_i8:.*]] = getelementptr inbounds i8* %[[THIS_i8]], i32 %[[VBASE_OFFSET]]
// CHECK: %[[VTORDISP_i8:.*]] = getelementptr i8* %[[VBASE_i8]], i32 -4
// CHECK: %[[VTORDISP_PTR:.*]] = bitcast i8* %[[VTORDISP_i8]] to i32*
// CHECK: store i32 %[[VTORDISP_VAL]], i32* %[[VTORDISP_PTR]]
foo(); // Avoid the "trivial destructor" optimization.
// CHECK: ret
}
void B::foo() {
// CHECK: define x86_thiscallcc void @"\01?foo@B@@UAEXXZ"(i8*
// CHECK-LABEL: define x86_thiscallcc void @"\01?foo@B@@UAEXXZ"(i8*
//
// B::foo gets 'this' cast to VBase* in ECX (i.e. this+8) so we
// need to adjust 'this' before use.
@ -58,7 +109,7 @@ void B::foo() {
}
void call_vbase_bar(B *obj) {
// CHECK: define void @"\01?call_vbase_bar@@YAXPAUB@@@Z"(%struct.B* %obj)
// CHECK-LABEL: define void @"\01?call_vbase_bar@@YAXPAUB@@@Z"(%struct.B* %obj)
// CHECK: %[[OBJ:.*]] = load %struct.B
obj->bar();
@ -76,7 +127,7 @@ void call_vbase_bar(B *obj) {
// CHECK: %[[VBASE_i8:.*]] = getelementptr inbounds i8* %[[OBJ_i8]], i32 %[[VBOFFSET]]
// CHECK: %[[VFPTR:.*]] = bitcast i8* %[[VBASE_i8]] to void (i8*)***
// CHECK: %[[VFTABLE:.*]] = load void (i8*)*** %[[VFPTR]]
// CHECK: %[[VFUN:.*]] = getelementptr inbounds void (i8*)** %[[VFTABLE]], i64 1
// CHECK: %[[VFUN:.*]] = getelementptr inbounds void (i8*)** %[[VFTABLE]], i64 2
// CHECK: %[[VFUN_VALUE:.*]] = load void (i8*)** %[[VFUN]]
//
// CHECK: %[[OBJ_i8:.*]] = bitcast %struct.B* %[[OBJ]] to i8*
@ -101,3 +152,38 @@ struct C : B {
// Used to crash on an assertion.
C::C() {}
namespace multiple_vbases {
struct A {
virtual void a();
};
struct B {
virtual void b();
};
struct C {
virtual void c();
};
struct D : virtual A, virtual B, virtual C {
virtual void a();
virtual void b();
virtual void c();
D();
};
D::D() {
// CHECK-LABEL: define x86_thiscallcc %"struct.multiple_vbases::D"* @"\01??0D@multiple_vbases@@QAE@XZ"
// Just make sure we emit 3 vtordisps after initializing vfptrs.
// CHECK: store [1 x i8*]* @"\01??_7D@multiple_vbases@@6BA@1@@", [1 x i8*]** %{{.*}}
// CHECK: store [1 x i8*]* @"\01??_7D@multiple_vbases@@6BB@1@@", [1 x i8*]** %{{.*}}
// CHECK: store [1 x i8*]* @"\01??_7D@multiple_vbases@@6BC@1@@", [1 x i8*]** %{{.*}}
// ...
// CHECK: store i32 %{{.*}}, i32* %{{.*}}
// CHECK: store i32 %{{.*}}, i32* %{{.*}}
// CHECK: store i32 %{{.*}}, i32* %{{.*}}
// CHECK: ret
}
}