diff --git a/clang/include/clang/AST/Decl.h b/clang/include/clang/AST/Decl.h index 193c3286f810..6ca14ce87496 100644 --- a/clang/include/clang/AST/Decl.h +++ b/clang/include/clang/AST/Decl.h @@ -1515,6 +1515,10 @@ public: return hasBody(Definition); } + /// hasTrivialBody - Returns whether the function has a trivial body that does + /// not require any specific codegen. + bool hasTrivialBody() const; + /// isDefined - Returns true if the function is defined at all, including /// a deleted definition. Except for the behavior when the function is /// deleted, behaves like hasBody. diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp index b57c6ab7d76d..d4df017383d1 100644 --- a/clang/lib/AST/Decl.cpp +++ b/clang/lib/AST/Decl.cpp @@ -1422,6 +1422,20 @@ bool FunctionDecl::hasBody(const FunctionDecl *&Definition) const { return false; } +bool FunctionDecl::hasTrivialBody() const +{ + Stmt *S = getBody(); + if (!S) { + // Since we don't have a body for this function, we don't know if it's + // trivial or not. + return false; + } + + if (isa(S) && cast(S)->body_empty()) + return true; + return false; +} + bool FunctionDecl::isDefined(const FunctionDecl *&Definition) const { for (redecl_iterator I = redecls_begin(), E = redecls_end(); I != E; ++I) { if (I->IsDeleted || I->Body || I->IsLateTemplateParsed) { diff --git a/clang/lib/CodeGen/CGCXX.cpp b/clang/lib/CodeGen/CGCXX.cpp index 4390f3a3e3e9..f6fc202eaae2 100644 --- a/clang/lib/CodeGen/CGCXX.cpp +++ b/clang/lib/CodeGen/CGCXX.cpp @@ -28,17 +28,6 @@ using namespace clang; using namespace CodeGen; -/// Determines whether the given function has a trivial body that does -/// not require any specific codegen. -static bool HasTrivialBody(const FunctionDecl *FD) { - Stmt *S = FD->getBody(); - if (!S) - return true; - if (isa(S) && cast(S)->body_empty()) - return true; - return false; -} - /// Try to emit a base destructor as an alias to its primary /// base-class destructor. bool CodeGenModule::TryEmitBaseDestructorAsAlias(const CXXDestructorDecl *D) { @@ -47,7 +36,7 @@ bool CodeGenModule::TryEmitBaseDestructorAsAlias(const CXXDestructorDecl *D) { // If the destructor doesn't have a trivial body, we have to emit it // separately. - if (!HasTrivialBody(D)) + if (!D->hasTrivialBody()) return true; const CXXRecordDecl *Class = D->getParent(); diff --git a/clang/lib/CodeGen/CGClass.cpp b/clang/lib/CodeGen/CGClass.cpp index 4172948b6023..785b9e129a1a 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()); diff --git a/clang/test/CodeGenCXX/mangle-subst-std.cpp b/clang/test/CodeGenCXX/mangle-subst-std.cpp index fea3582d321a..c54d3e5297f0 100644 --- a/clang/test/CodeGenCXX/mangle-subst-std.cpp +++ b/clang/test/CodeGenCXX/mangle-subst-std.cpp @@ -8,8 +8,8 @@ // CHECK: @_ZTCSd0_Si = linkonce_odr unnamed_addr constant // CHECK: @_ZTCSd16_So = linkonce_odr unnamed_addr constant // CHECK: @_ZTTSo = linkonce_odr unnamed_addr constant -// CHECK: @_ZTVSo = linkonce_odr unnamed_addr constant // CHECK: @_ZTTSi = linkonce_odr unnamed_addr constant +// CHECK: @_ZTVSo = linkonce_odr unnamed_addr constant // CHECK: @_ZTVSi = linkonce_odr unnamed_addr constant namespace std { struct A { A(); }; diff --git a/clang/test/CodeGenCXX/skip-vtable-pointer-initialization.cpp b/clang/test/CodeGenCXX/skip-vtable-pointer-initialization.cpp new file mode 100644 index 000000000000..f992bd339df0 --- /dev/null +++ b/clang/test/CodeGenCXX/skip-vtable-pointer-initialization.cpp @@ -0,0 +1,106 @@ +// RUN: %clang_cc1 %s -triple=x86_64-apple-darwin10 -emit-llvm -o - | FileCheck %s + +namespace Test1 { + +// Check that we don't initialize the vtable pointer in A::~A(), since the destructor body is trivial. +struct A { + virtual void f(); + ~A(); +}; + +// CHECK: define void @_ZN5Test11AD2Ev +// CHECK-NOT: store i8** getelementptr inbounds ([3 x i8*]* @_ZTVN5Test11AE, i64 0, i64 2), i8*** +A::~A() +{ +} + +} + +namespace Test2 { + +// Check that we do initialize the vtable pointer in A::~A() since the destructor body isn't trivial. +struct A { + virtual void f(); + ~A(); +}; + +// CHECK: define void @_ZN5Test21AD2Ev +// CHECK: store i8** getelementptr inbounds ([3 x i8*]* @_ZTVN5Test21AE, i64 0, i64 2), i8*** +A::~A() { + f(); +} + +} + +namespace Test3 { + +// Check that we don't initialize the vtable pointer in A::~A(), since the destructor body is trivial +// and Field's destructor body is also trivial. +struct Field { + ~Field() { } +}; + +struct A { + virtual void f(); + ~A(); + + Field field; +}; + +// CHECK: define void @_ZN5Test31AD2Ev +// CHECK-NOT: store i8** getelementptr inbounds ([3 x i8*]* @_ZTVN5Test31AE, i64 0, i64 2), i8*** +A::~A() { + +} + +} + +namespace Test4 { + +// Check that we do initialize the vtable pointer in A::~A(), since Field's destructor body +// isn't trivial. + +void f(); + +struct Field { + ~Field() { f(); } +}; + +struct A { + virtual void f(); + ~A(); + + Field field; +}; + +// CHECK: define void @_ZN5Test41AD2Ev +// CHECK: store i8** getelementptr inbounds ([3 x i8*]* @_ZTVN5Test41AE, i64 0, i64 2), i8*** +A::~A() +{ +} + +} + +namespace Test5 { + +// Check that we do initialize the vtable pointer in A::~A(), since Field's destructor isn't +// available in this translation unit. + +struct Field { + ~Field(); +}; + +struct A { + virtual void f(); + ~A(); + + Field field; +}; + +// CHECK: define void @_ZN5Test51AD2Ev +// CHECK: store i8** getelementptr inbounds ([3 x i8*]* @_ZTVN5Test51AE, i64 0, i64 2), i8*** +A::~A() +{ +} + +} \ No newline at end of file