diff options
Diffstat (limited to 'clang/lib/CodeGen/MicrosoftCXXABI.cpp')
| -rw-r--r-- | clang/lib/CodeGen/MicrosoftCXXABI.cpp | 48 |
1 files changed, 47 insertions, 1 deletions
diff --git a/clang/lib/CodeGen/MicrosoftCXXABI.cpp b/clang/lib/CodeGen/MicrosoftCXXABI.cpp index 22d548857b7..0e01d8bacfc 100644 --- a/clang/lib/CodeGen/MicrosoftCXXABI.cpp +++ b/clang/lib/CodeGen/MicrosoftCXXABI.cpp @@ -65,11 +65,51 @@ public: llvm::BasicBlock *EmitCtorCompleteObjectHandler(CodeGenFunction &CGF, const CXXRecordDecl *RD); - void BuildDestructorSignature(const CXXDestructorDecl *Ctor, + // Background on MSVC destructors + // ============================== + // + // Both Itanium and MSVC ABIs have destructor variants. The variant names + // roughly correspond in the following way: + // Itanium Microsoft + // Base -> no name, just ~Class + // Complete -> vbase destructor + // Deleting -> scalar deleting destructor + // vector deleting destructor + // + // The base and complete destructors are the same as in Itanium, although the + // complete destructor does not accept a VTT parameter when there are virtual + // bases. A separate mechanism involving vtordisps is used to ensure that + // virtual methods of destroyed subobjects are not called. + // + // The deleting destructors accept an i32 bitfield as a second parameter. Bit + // 1 indicates if the memory should be deleted. Bit 2 indicates if the this + // pointer points to an array. The scalar deleting destructor assumes that + // bit 2 is zero, and therefore does not contain a loop. + // + // For virtual destructors, only one entry is reserved in the vftable, and it + // always points to the vector deleting destructor. The vector deleting + // destructor is the most general, so it can be used to destroy objects in + // place, delete single heap objects, or delete arrays. + // + // A TU defining a non-inline destructor is only guaranteed to emit a base + // destructor, and all of the other variants are emitted on an as-needed basis + // in COMDATs. Because a non-base destructor can be emitted in a TU that + // lacks a definition for the destructor, non-base destructors must always + // delegate to or alias the base destructor. + + void BuildDestructorSignature(const CXXDestructorDecl *Dtor, CXXDtorType Type, CanQualType &ResTy, SmallVectorImpl<CanQualType> &ArgTys); + /// Non-base dtors should be emitted as delegating thunks in this ABI. + bool useThunkForDtorVariant(const CXXDestructorDecl *Dtor, + CXXDtorType DT) const { + return DT != Dtor_Base; + } + + void EmitCXXDestructors(const CXXDestructorDecl *D); + void BuildInstanceFunctionParams(CodeGenFunction &CGF, QualType &ResTy, FunctionArgList &Params); @@ -387,6 +427,12 @@ void MicrosoftCXXABI::BuildDestructorSignature(const CXXDestructorDecl *Dtor, } } +void MicrosoftCXXABI::EmitCXXDestructors(const CXXDestructorDecl *D) { + // The TU defining a dtor is only guaranteed to emit a base destructor. All + // other destructor variants are delegating thunks. + CGM.EmitGlobal(GlobalDecl(D, Dtor_Base)); +} + static bool IsDeletingDtor(GlobalDecl GD) { const CXXMethodDecl* MD = cast<CXXMethodDecl>(GD.getDecl()); if (isa<CXXDestructorDecl>(MD)) { |
