From 9bd7d16440f97821fe2d036f3118c5c7aae926bb Mon Sep 17 00:00:00 2001 From: Anders Carlsson Date: Sat, 14 May 2011 23:26:09 +0000 Subject: When emitting the destructor for a class with a vtable, if we can determine that the destructor body is trivial and that all member variables also have either trivial destructors or trivial destructor bodies, we don't need to initialize the vtable pointers since no virtual member functions will be called on the destructor. Fixes PR9181. llvm-svn: 131368 --- clang/lib/CodeGen/CGClass.cpp | 35 ++++++++++++++++++++++++++++++++++- 1 file changed, 34 insertions(+), 1 deletion(-) (limited to 'clang/lib/CodeGen/CGClass.cpp') diff --git a/clang/lib/CodeGen/CGClass.cpp b/clang/lib/CodeGen/CGClass.cpp index 4172948b602..785b9e129a1 100644 --- a/clang/lib/CodeGen/CGClass.cpp +++ b/clang/lib/CodeGen/CGClass.cpp @@ -741,6 +741,38 @@ void CodeGenFunction::EmitCtorPrologue(const CXXConstructorDecl *CD, EmitMemberInitializer(*this, ClassDecl, MemberInitializers[I], CD, Args); } +/// CanSkipVTablePointerInitialization - Check whether we need to initialize +/// any vtable pointers before calling this destructor. +static bool CanSkipVTablePointerInitialization(ASTContext &Context, + const CXXDestructorDecl *Dtor) { + if (!Dtor->hasTrivialBody()) + return false; + + // Check the fields. + const CXXRecordDecl *ClassDecl = Dtor->getParent(); + for (CXXRecordDecl::field_iterator I = ClassDecl->field_begin(), + E = ClassDecl->field_end(); I != E; ++I) { + const FieldDecl *Field = *I; + + QualType FieldBaseElementType = + Context.getBaseElementType(Field->getType()); + + const RecordType *RT = FieldBaseElementType->getAs(); + if (!RT) + continue; + + CXXRecordDecl *FieldClassDecl = cast(RT->getDecl()); + if (FieldClassDecl->hasTrivialDestructor()) + continue; + if (FieldClassDecl->getDestructor()->hasTrivialBody()) + continue; + + return false; + } + + return true; +} + /// EmitDestructorBody - Emits the body of the current destructor. void CodeGenFunction::EmitDestructorBody(FunctionArgList &Args) { const CXXDestructorDecl *Dtor = cast(CurGD.getDecl()); @@ -792,7 +824,8 @@ void CodeGenFunction::EmitDestructorBody(FunctionArgList &Args) { EnterDtorCleanups(Dtor, Dtor_Base); // Initialize the vtable pointers before entering the body. - InitializeVTablePointers(Dtor->getParent()); + if (!CanSkipVTablePointerInitialization(getContext(), Dtor)) + InitializeVTablePointers(Dtor->getParent()); if (isTryBody) EmitStmt(cast(Body)->getTryBlock()); -- cgit v1.2.3