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Emit vbase offsets. 

llvm-svn: 96329
This commit is contained in:
Anders Carlsson 2010-02-16 04:59:55 +00:00
parent dc2dba306c
commit 77904f1d5b
2 changed files with 63 additions and 4 deletions
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40
clang/lib/CodeGen/CGVtable.cpp
View File

@ -912,6 +912,27 @@ VtableBuilder::AddVCallAndVBaseOffsets(const CXXRecordDecl *RD,
void VtableBuilder::AddVBaseOffsets(const CXXRecordDecl *RD,
int64_t OffsetToTop,
VisitedVirtualBasesSetTy &VBases) {
const ASTRecordLayout &MostDerivedClassLayout =
Context.getASTRecordLayout(MostDerivedClass);
// Add vbase offsets.
for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
E = RD->bases_end(); I != E; ++I) {
const CXXRecordDecl *BaseDecl =
cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
// Check if this is a virtual base that we haven't visited before.
if (I->isVirtual() && VBases.insert(BaseDecl)) {
// FIXME: We shouldn't use / 8 here.
uint64_t Offset =
OffsetToTop + MostDerivedClassLayout.getVBaseClassOffset(BaseDecl) / 8;
VCallAndVBaseOffsets.push_back(VtableComponent::MakeVBaseOffset(Offset));
}
// Check the base class looking for more vbase offsets.
AddVBaseOffsets(BaseDecl, OffsetToTop, VBases);
}
}
void
@ -1008,13 +1029,22 @@ VtableBuilder::AddMethods(BaseSubobject Base, PrimaryBasesSetTy &PrimaryBases) {
void VtableBuilder::LayoutVtable(BaseSubobject Base) {
const CXXRecordDecl *RD = Base.getBase();
assert(RD->isDynamicClass() && "class does not have a vtable!");
// First, add the offset to top.
int64_t OffsetToTop = -(int64_t)Base.getBaseOffset() / 8;
// Add vcall and vbase offsets for this vtable.
VisitedVirtualBasesSetTy VBases;
AddVCallAndVBaseOffsets(RD, OffsetToTop, VBases);
// Reverse them and add them to the vtable components.
std::reverse(VCallAndVBaseOffsets.begin(), VCallAndVBaseOffsets.end());
Components.append(VCallAndVBaseOffsets.begin(), VCallAndVBaseOffsets.end());
VCallAndVBaseOffsets.clear();
// Add the offset to top.
// FIXME: This is not going to be right for construction vtables.
// FIXME: We should not use / 8 here.
int64_t OffsetToTop = -(int64_t)Base.getBaseOffset() / 8;
Components.push_back(VtableComponent::MakeOffsetToTop(OffsetToTop));
// Next, add the RTTI.
@ -1138,6 +1168,10 @@ void VtableBuilder::dumpLayout(llvm::raw_ostream& Out) {
assert(false && "Unhandled component kind!");
break;
case VtableComponent::CK_VBaseOffset:
Out << "vbase_offset (" << Component.getVBaseOffset() << ")";
break;
case VtableComponent::CK_OffsetToTop:
Out << "offset_to_top (" << Component.getOffsetToTop() << ")";
break;

25
clang/test/CodeGenCXX/vtable-layout.cpp
View File

@ -340,3 +340,28 @@ struct B : A {
void B::f() { }
}
namespace Test9 {
// Simple test of vbase offsets.
struct A1 { int a1; };
struct A2 { int a2; };
// CHECK: Vtable for 'Test9::B' (5 entries).
// CHECK-NEXT: 0 | vbase_offset (16)
// CHECK-NEXT: 1 | vbase_offset (12)
// CHECK-NEXT: 2 | offset_to_top (0)
// CHECK-NEXT: 3 | Test9::B RTTI
// CHECK-NEXT: -- (Test9::B, 0) vtable address --
// CHECK-NEXT: 4 | void Test9::B::f()
struct B : virtual A1, virtual A2 {
int b;
virtual void f();
};
void B::f() { }
}