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[codeview] Pass through vftable shape information 

The shape is really just the number of methods in the vftable, since we
don't support 16 bit far calls. All calls are near. Encode this number
in the size of the artificial __vtbl_ptr_type DIDerivedType that we
generate. For DWARF, this will be a normal pointer, but for codeview
this will be a wide pointer that gets pattern matched into a
VFTableShape record. Insert this type into the element list of all
dynamic classes when emitting CodeView, so that the backend can emit the
shape even if the vptr lives in a primary base class.

Fixes PR28150

llvm-svn: 280255
This commit is contained in:
Reid Kleckner 2016-08-31 16:11:43 +00:00
parent 9dac47319d
commit dc124996d2
3 changed files with 48 additions and 13 deletions
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49
clang/lib/CodeGen/CGDebugInfo.cpp
View File

@ -1549,22 +1549,49 @@ StringRef CGDebugInfo::getVTableName(const CXXRecordDecl *RD) {
}
void CGDebugInfo::CollectVTableInfo(const CXXRecordDecl *RD, llvm::DIFile *Unit,
SmallVectorImpl<llvm::Metadata *> &EltTys) {
const ASTRecordLayout &RL = CGM.getContext().getASTRecordLayout(RD);
// If there is a primary base then it will hold vtable info.
if (RL.getPrimaryBase())
return;
SmallVectorImpl<llvm::Metadata *> &EltTys,
llvm::DICompositeType *RecordTy) {
// If this class is not dynamic then there is not any vtable info to collect.
if (!RD->isDynamicClass())
return;
// CodeView needs to know how large the vtable of every dynamic class is, so
// emit a special named pointer type into the element list. The vptr type
// points to this type as well.
llvm::DIType *VPtrTy = nullptr;
bool NeedVTableShape = CGM.getCodeGenOpts().EmitCodeView &&
CGM.getTarget().getCXXABI().isMicrosoft();
if (NeedVTableShape) {
uint64_t PtrWidth =
CGM.getContext().getTypeSize(CGM.getContext().VoidPtrTy);
const VTableLayout &VFTLayout =
CGM.getMicrosoftVTableContext().getVFTableLayout(RD, CharUnits::Zero());
unsigned VSlotCount =
VFTLayout.getNumVTableComponents() - CGM.getLangOpts().RTTIData;
unsigned VTableWidth = PtrWidth * VSlotCount;
// Create a very wide void* type and insert it directly in the element list.
llvm::DIType *VTableType =
DBuilder.createPointerType(nullptr, VTableWidth, 0, "__vtbl_ptr_type");
EltTys.push_back(VTableType);
// The vptr is a pointer to this special vtable type.
VPtrTy = DBuilder.createPointerType(VTableType, PtrWidth);
}
// If there is a primary base then the artificial vptr member lives there.
const ASTRecordLayout &RL = CGM.getContext().getASTRecordLayout(RD);
if (RL.getPrimaryBase())
return;
if (!VPtrTy)
VPtrTy = getOrCreateVTablePtrType(Unit);
unsigned Size = CGM.getContext().getTypeSize(CGM.getContext().VoidPtrTy);
llvm::DIType *VPTR = DBuilder.createMemberType(
llvm::DIType *VPtrMember = DBuilder.createMemberType(
Unit, getVTableName(RD), Unit, 0, Size, 0, 0,
llvm::DINode::FlagArtificial, getOrCreateVTablePtrType(Unit));
EltTys.push_back(VPTR);
llvm::DINode::FlagArtificial, VPtrTy);
EltTys.push_back(VPtrMember);
}
llvm::DIType *CGDebugInfo::getOrCreateRecordType(QualType RTy,
@ -1761,7 +1788,7 @@ llvm::DIType *CGDebugInfo::CreateTypeDefinition(const RecordType *Ty) {
const auto *CXXDecl = dyn_cast<CXXRecordDecl>(RD);
if (CXXDecl) {
CollectCXXBases(CXXDecl, DefUnit, EltTys, FwdDecl);
CollectVTableInfo(CXXDecl, DefUnit, EltTys);
CollectVTableInfo(CXXDecl, DefUnit, EltTys, FwdDecl);
}
// Collect data fields (including static variables and any initializers).

3
clang/lib/CodeGen/CGDebugInfo.h
View File

@ -264,7 +264,8 @@ class CGDebugInfo {
/// If the C++ class has vtable info then insert appropriate debug
/// info entry in EltTys vector.
void CollectVTableInfo(const CXXRecordDecl *Decl, llvm::DIFile *F,
SmallVectorImpl<llvm::Metadata *> &EltTys);
SmallVectorImpl<llvm::Metadata *> &EltTys,
llvm::DICompositeType *RecordTy);
/// @}
/// Create a new lexical block node and push it on the stack.

9
clang/test/CodeGenCXX/debug-info-ms-abi.cpp
View File

@ -15,7 +15,14 @@ Foo::Nested n;
// CHECK-SAME: elements: ![[elements:[0-9]+]]
// CHECK-SAME: identifier: ".?AUFoo@@"
// CHECK: ![[elements]] = !{![[vptr:[0-9]+]], ![[Nested:[0-9]+]], ![[f:[0-9]+]], ![[g:[0-9]+]], ![[h:[0-9]+]]}
// CHECK: ![[elements]] = !{![[vshape:[0-9]+]], ![[vptr:[0-9]+]], ![[Nested:[0-9]+]], ![[f:[0-9]+]], ![[g:[0-9]+]], ![[h:[0-9]+]]}
// CHECK: ![[vshape]] = !DIDerivedType(tag: DW_TAG_pointer_type, name: "__vtbl_ptr_type", baseType: null, size: 96)
// CHECK: ![[vptr]] = !DIDerivedType(tag: DW_TAG_member, name: "_vptr$Foo",
// CHECK-SAME: baseType: ![[vptr_ty:[0-9]+]],
// CHECK: ![[vptr_ty]] = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: ![[vshape]], size: 32
// CHECK: ![[Nested]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "Nested",
// CHECK-SAME: identifier: ".?AUNested@Foo@@"