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Split adding the primary virtual base offsets out into a separate pass. This fixes a bug where we would lay out virtual bases in the wrong order. 

llvm-svn: 101373
This commit is contained in:
Anders Carlsson 2010-04-15 16:12:58 +00:00
parent c1cf814c8b
commit ea7b18298e
3 changed files with 158 additions and 35 deletions
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101
clang/lib/AST/RecordLayoutBuilder.cpp
View File

@ -207,10 +207,66 @@ void ASTRecordLayoutBuilder::LayoutNonVirtualBase(const CXXRecordDecl *RD) {
assert(false && "Added same base offset more than once!");
}
void
ASTRecordLayoutBuilder::AddPrimaryVirtualBaseOffsets(const CXXRecordDecl *RD,
uint64_t Offset,
const CXXRecordDecl *MostDerivedClass) {
// We already have the offset for the primary base of the most derived class.
if (RD != MostDerivedClass) {
const ASTRecordLayout &Layout = Ctx.getASTRecordLayout(RD);
const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
// If this is a primary virtual base and we haven't seen it before, add it.
if (PrimaryBase && Layout.getPrimaryBaseWasVirtual() &&
!VBases.count(PrimaryBase))
VBases.insert(std::make_pair(PrimaryBase, Offset));
}
for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
E = RD->bases_end(); I != E; ++I) {
assert(!I->getType()->isDependentType() &&
"Cannot layout class with dependent bases.");
const CXXRecordDecl *BaseDecl =
cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
if (!BaseDecl->getNumVBases()) {
// This base isn't interesting since it doesn't have any virtual bases.
continue;
}
// Compute the offset of this base.
uint64_t BaseOffset;
if (I->isVirtual()) {
// If we don't know this vbase yet, don't visit it. It will be visited
// later.
if (!VBases.count(BaseDecl)) {
continue;
}
// Check if we've already visited this base.
if (!VisitedVirtualBases.insert(BaseDecl))
continue;
// We want the vbase offset from the class we're currently laying out.
BaseOffset = VBases[BaseDecl];
} else if (RD == MostDerivedClass) {
// We want the base offset from the class we're currently laying out.
assert(Bases.count(BaseDecl) && "Did not find base!");
BaseOffset = Bases[BaseDecl];
} else {
const ASTRecordLayout &Layout = Ctx.getASTRecordLayout(RD);
BaseOffset = Offset + Layout.getBaseClassOffset(BaseDecl);
}
AddPrimaryVirtualBaseOffsets(BaseDecl, BaseOffset, MostDerivedClass);
}
}
void
ASTRecordLayoutBuilder::LayoutVirtualBases(const CXXRecordDecl *RD,
uint64_t Offset,
const CXXRecordDecl *MostDerivedClass) {
const CXXRecordDecl *MostDerivedClass) {
const CXXRecordDecl *PrimaryBase;
bool PrimaryBaseIsVirtual;
@ -223,14 +279,6 @@ ASTRecordLayoutBuilder::LayoutVirtualBases(const CXXRecordDecl *RD,
PrimaryBaseIsVirtual = Layout.getPrimaryBaseWasVirtual();
}
// Check the primary base first.
if (PrimaryBase && PrimaryBaseIsVirtual &&
VisitedVirtualBases.insert(PrimaryBase)) {
assert(!VBases.count(PrimaryBase) && "vbase offset already exists!");
VBases.insert(std::make_pair(PrimaryBase, Offset));
}
for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
E = RD->bases_end(); I != E; ++I) {
assert(!I->getType()->isDependentType() &&
@ -259,27 +307,7 @@ ASTRecordLayoutBuilder::LayoutVirtualBases(const CXXRecordDecl *RD,
continue;
}
// Compute the offset of this base.
uint64_t BaseOffset;
if (I->isVirtual()) {
// If we don't know this vbase yet, don't visit it. It will be visited
// later.
if (!VBases.count(Base))
continue;
// We want the vbase offset from the class we're currently laying out.
BaseOffset = VBases[Base];
} else if (RD == MostDerivedClass) {
// We want the base offset from the class we're currently laying out.
assert(Bases.count(Base) && "Did not find base!");
BaseOffset = Bases[Base];
} else {
const ASTRecordLayout &Layout = Ctx.getASTRecordLayout(RD);
BaseOffset = Offset + Layout.getBaseClassOffset(Base);
}
LayoutVirtualBases(Base, BaseOffset, MostDerivedClass);
LayoutVirtualBases(Base, MostDerivedClass);
}
}
@ -501,9 +529,14 @@ void ASTRecordLayoutBuilder::Layout(const RecordDecl *D) {
NonVirtualSize = Size;
NonVirtualAlignment = Alignment;
// If this is a C++ class, lay out its virtual bases.
if (RD)
LayoutVirtualBases(RD, 0, RD);
// If this is a C++ class, lay out its virtual bases and add its primary
// virtual base offsets.
if (RD) {
LayoutVirtualBases(RD, RD);
VisitedVirtualBases.clear();
AddPrimaryVirtualBaseOffsets(RD, 0, RD);
}
// Finally, round the size of the total struct up to the alignment of the
// struct itself.

5
clang/lib/AST/RecordLayoutBuilder.h
View File

@ -112,8 +112,11 @@ class ASTRecordLayoutBuilder {
/// LayoutNonVirtualBase - Lays out a single non-virtual base.
void LayoutNonVirtualBase(const CXXRecordDecl *RD);
void AddPrimaryVirtualBaseOffsets(const CXXRecordDecl *RD, uint64_t Offset,
const CXXRecordDecl *MostDerivedClass);
/// LayoutVirtualBases - Lays out all the virtual bases.
void LayoutVirtualBases(const CXXRecordDecl *RD, uint64_t Offset,
void LayoutVirtualBases(const CXXRecordDecl *RD,
const CXXRecordDecl *MostDerivedClass);
/// LayoutVirtualBase - Lays out a single virtual base.

87
clang/test/CodeGenCXX/vtable-layout.cpp
View File

@ -1511,3 +1511,90 @@ struct F : E {
void F::f() { }
}
namespace Test35 {
// Test that we lay out the virtual bases of 'Test35::H' in the correct order.
struct A {
virtual void a();
int i;
};
struct B : virtual A {
virtual void b();
};
struct C {
virtual void c();
};
struct D : C, virtual B {
virtual void d();
};
struct E : D {
virtual void e();
bool b;
};
struct F : virtual D { };
struct G : virtual E { };
// CHECK: Vtable for 'Test35::H' (32 entries).
// CHECK-NEXT: 0 | vbase_offset (32)
// CHECK-NEXT: 1 | vbase_offset (0)
// CHECK-NEXT: 2 | vcall_offset (0)
// CHECK-NEXT: 3 | vcall_offset (0)
// CHECK-NEXT: 4 | vbase_offset (16)
// CHECK-NEXT: 5 | vbase_offset (8)
// CHECK-NEXT: 6 | offset_to_top (0)
// CHECK-NEXT: 7 | Test35::H RTTI
// CHECK-NEXT: -- (Test35::C, 0) vtable address --
// CHECK-NEXT: -- (Test35::D, 0) vtable address --
// CHECK-NEXT: -- (Test35::F, 0) vtable address --
// CHECK-NEXT: -- (Test35::H, 0) vtable address --
// CHECK-NEXT: 8 | void Test35::C::c()
// CHECK-NEXT: 9 | void Test35::D::d()
// CHECK-NEXT: 10 | void Test35::H::h()
// CHECK-NEXT: 11 | vbase_offset (0)
// CHECK-NEXT: 12 | vbase_offset (24)
// CHECK-NEXT: 13 | vcall_offset (0)
// CHECK-NEXT: 14 | vbase_offset (8)
// CHECK-NEXT: 15 | offset_to_top (-8)
// CHECK-NEXT: 16 | Test35::H RTTI
// CHECK-NEXT: -- (Test35::B, 8) vtable address --
// CHECK-NEXT: -- (Test35::G, 8) vtable address --
// CHECK-NEXT: 17 | void Test35::B::b()
// CHECK-NEXT: 18 | vcall_offset (0)
// CHECK-NEXT: 19 | offset_to_top (-16)
// CHECK-NEXT: 20 | Test35::H RTTI
// CHECK-NEXT: -- (Test35::A, 16) vtable address --
// CHECK-NEXT: 21 | void Test35::A::a()
// CHECK-NEXT: 22 | vcall_offset (0)
// CHECK-NEXT: 23 | vcall_offset (0)
// CHECK-NEXT: 24 | vcall_offset (0)
// CHECK-NEXT: 25 | vbase_offset (-16)
// CHECK-NEXT: 26 | vbase_offset (-24)
// CHECK-NEXT: 27 | offset_to_top (-32)
// CHECK-NEXT: 28 | Test35::H RTTI
// CHECK-NEXT: -- (Test35::C, 32) vtable address --
// CHECK-NEXT: -- (Test35::D, 32) vtable address --
// CHECK-NEXT: -- (Test35::E, 32) vtable address --
// CHECK-NEXT: 29 | void Test35::C::c()
// CHECK-NEXT: 30 | void Test35::D::d()
// CHECK-NEXT: 31 | void Test35::E::e()
// CHECK: Virtual base offset offsets for 'Test35::H' (4 entries).
// CHECK-NEXT: Test35::A | -32
// CHECK-NEXT: Test35::B | -24
// CHECK-NEXT: Test35::D | -56
// CHECK-NEXT: Test35::E | -64
struct H : F, G {
virtual void h();
};
void H::h() { }
}