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Fix a vftable mangling bug 

We need to walk the class hierarchy twice: once in depth-first base
specifier order for mangling and again in depth-first layout order for
vftable layout.

Vftable layout seems to depend on the full path from the most derived
class to the base containing the vfptr.

Fixes PR21031.

llvm-svn: 218285
This commit is contained in:
Reid Kleckner 2014-09-22 23:14:46 +00:00
parent 4bc685c206
commit 15fdcf19ba
2 changed files with 95 additions and 19 deletions
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69
clang/lib/AST/VTableBuilder.cpp
View File

@ -3162,16 +3162,9 @@ void MicrosoftVTableContext::computeVTablePaths(bool ForVBTables,
Paths.push_back(new VPtrInfo(RD));
// Recursive case: get all the vbtables from our bases and remove anything
// that shares a virtual base. Look at non-virtual bases first so we get
// longer inheritance paths from the derived class to the virtual bases.
llvm::SmallVector<CXXBaseSpecifier, 10> Bases;
std::copy_if(RD->bases_begin(), RD->bases_end(), std::back_inserter(Bases),
[](CXXBaseSpecifier bs) { return !bs.isVirtual(); });
std::copy_if(RD->bases_begin(), RD->bases_end(), std::back_inserter(Bases),
[](CXXBaseSpecifier bs) { return bs.isVirtual(); });
// that shares a virtual base.
llvm::SmallPtrSet<const CXXRecordDecl*, 4> VBasesSeen;
for (const auto &B : Bases) {
for (const auto &B : RD->bases()) {
const CXXRecordDecl *Base = B.getType()->getAsCXXRecordDecl();
if (B.isVirtual() && VBasesSeen.count(Base))
continue;
@ -3196,10 +3189,6 @@ void MicrosoftVTableContext::computeVTablePaths(bool ForVBTables,
if (P->MangledPath.empty() || P->MangledPath.back() != Base)
P->NextBaseToMangle = Base;
// Keep track of the full path.
// FIXME: Why do we need this?
P->PathToBaseWithVPtr.insert(P->PathToBaseWithVPtr.begin(), Base);
// Keep track of which vtable the derived class is going to extend with
// new methods or bases. We append to either the vftable of our primary
// base, or the first non-virtual base that has a vbtable.
@ -3287,6 +3276,59 @@ MicrosoftVTableContext::~MicrosoftVTableContext() {
llvm::DeleteContainerSeconds(VBaseInfo);
}
static bool
findPathForVPtr(ASTContext &Context, const ASTRecordLayout &MostDerivedLayout,
const CXXRecordDecl *RD, CharUnits Offset,
llvm::SmallPtrSetImpl<const CXXRecordDecl *> &VBasesSeen,
VPtrInfo::BasePath &FullPath, VPtrInfo *Info) {
if (RD == Info->BaseWithVPtr && Offset == Info->FullOffsetInMDC) {
Info->PathToBaseWithVPtr = FullPath;
return true;
}
const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
// Recurse with non-virtual bases first.
// FIXME: Does this need to be in layout order? Virtual bases will be in base
// specifier order, which isn't necessarily layout order.
SmallVector<CXXBaseSpecifier, 4> Bases(RD->bases_begin(), RD->bases_end());
std::stable_partition(Bases.begin(), Bases.end(),
[](CXXBaseSpecifier bs) { return !bs.isVirtual(); });
for (const auto &B : Bases) {
const CXXRecordDecl *Base = B.getType()->getAsCXXRecordDecl();
CharUnits NewOffset;
if (!B.isVirtual())
NewOffset = Offset + Layout.getBaseClassOffset(Base);
else {
if (VBasesSeen.count(Base))
return false;
VBasesSeen.insert(Base);
NewOffset = MostDerivedLayout.getVBaseClassOffset(Base);
}
FullPath.push_back(Base);
if (findPathForVPtr(Context, MostDerivedLayout, Base, NewOffset, VBasesSeen,
FullPath, Info))
return true;
FullPath.pop_back();
}
return false;
}
static void computeFullPathsForVFTables(ASTContext &Context,
const CXXRecordDecl *RD,
VPtrInfoVector &Paths) {
llvm::SmallPtrSet<const CXXRecordDecl*, 4> VBasesSeen;
const ASTRecordLayout &MostDerivedLayout = Context.getASTRecordLayout(RD);
VPtrInfo::BasePath FullPath;
for (VPtrInfo *Info : Paths) {
findPathForVPtr(Context, MostDerivedLayout, RD, CharUnits::Zero(),
VBasesSeen, FullPath, Info);
VBasesSeen.clear();
FullPath.clear();
}
}
void MicrosoftVTableContext::computeVTableRelatedInformation(
const CXXRecordDecl *RD) {
assert(RD->isDynamicClass());
@ -3299,6 +3341,7 @@ void MicrosoftVTableContext::computeVTableRelatedInformation(
VPtrInfoVector *VFPtrs = new VPtrInfoVector();
computeVTablePaths(/*ForVBTables=*/false, RD, *VFPtrs);
computeFullPathsForVFTables(Context, RD, *VFPtrs);
VFPtrLocations[RD] = VFPtrs;
MethodVFTableLocationsTy NewMethodLocations;

45
clang/test/CodeGenCXX/microsoft-abi-vtables-virtual-inheritance.cpp
View File

@ -573,10 +573,6 @@ struct Q {
// PR19172: Yet another diamond we miscompiled.
struct R : virtual Q, X {
// CHECK-LABEL: VFTable for 'vdtors::X' in 'vdtors::R' (2 entries).
// CHECK-NEXT: 0 | vdtors::R::~R() [scalar deleting]
// CHECK-NEXT: 1 | void vdtors::X::zzz()
// CHECK-LABEL: VFTable for 'vdtors::Q' in 'vdtors::R' (1 entry).
// CHECK-NEXT: 0 | vdtors::R::~R() [scalar deleting]
// CHECK-NEXT: [this adjustment: -8 non-virtual]
@ -584,6 +580,10 @@ struct R : virtual Q, X {
// CHECK-LABEL: Thunks for 'vdtors::R::~R()' (1 entry).
// CHECK-NEXT: 0 | [this adjustment: -8 non-virtual]
// CHECK-LABEL: VFTable for 'vdtors::X' in 'vdtors::R' (2 entries).
// CHECK-NEXT: 0 | vdtors::R::~R() [scalar deleting]
// CHECK-NEXT: 1 | void vdtors::X::zzz()
// CHECK-LABEL: VFTable indices for 'vdtors::R' (1 entry).
// CHECK-NEXT: 0 | vdtors::R::~R() [scalar deleting]
virtual ~R();
@ -694,10 +694,10 @@ struct X : virtual B {};
struct Y : virtual X, B {
Y();
// CHECK-LABEL: VFTable for 'B' in 'pr19066::Y' (1 entry).
// CHECK-LABEL: VFTable for 'B' in 'pr19066::X' in 'pr19066::Y' (1 entry).
// CHECK-NEXT: 0 | void B::g()
// CHECK-LABEL: VFTable for 'B' in 'pr19066::X' in 'pr19066::Y' (1 entry).
// CHECK-LABEL: VFTable for 'B' in 'pr19066::Y' (1 entry).
// CHECK-NEXT: 0 | void B::g()
};
@ -772,3 +772,36 @@ struct __declspec(dllexport) A {
virtual void f() = delete;
};
}
namespace pr21031_1 {
// This ordering of base specifiers regressed in r202425.
struct A { virtual void f(void); };
struct B : virtual A { virtual void g(void); };
struct C : virtual A, B { C(); };
C::C() {}
// CHECK-LABEL: VFTable for 'pr21031_1::A' in 'pr21031_1::B' in 'pr21031_1::C' (1 entry)
// CHECK-NEXT: 0 | void pr21031_1::A::f()
// CHECK-LABEL: VFTable for 'pr21031_1::B' in 'pr21031_1::C' (1 entry)
// CHECK-NEXT: 0 | void pr21031_1::B::g()
// MANGLING-DAG: @"\01??_7C@pr21031_1@@6BB@1@@" = {{.*}} constant [1 x i8*]
// MANGLING-DAG: @"\01??_7C@pr21031_1@@6B@" = {{.*}} constant [1 x i8*]
}
namespace pr21031_2 {
struct A { virtual void f(void); };
struct B : virtual A { virtual void g(void); };
struct C : B, virtual A { C(); };
C::C() {}
// CHECK-LABEL: VFTable for 'pr21031_2::B' in 'pr21031_2::C' (1 entry)
// CHECK-NEXT: 0 | void pr21031_2::B::g()
// CHECK-LABEL: VFTable for 'pr21031_2::A' in 'pr21031_2::B' in 'pr21031_2::C' (1 entry)
// CHECK-NEXT: 0 | void pr21031_2::A::f()
// MANGLING-DAG: @"\01??_7C@pr21031_2@@6BA@1@@" = {{.*}} constant [1 x i8*]
// MANGLING-DAG: @"\01??_7C@pr21031_2@@6BB@1@@" = {{.*}} constant [1 x i8*]
}