diff options
| -rw-r--r-- | lib/CodeGen/CGClass.cpp | 30 | ||||
| -rw-r--r-- | test/CodeGenCXX/constructor-init.cpp | 32 |
2 files changed, 62 insertions, 0 deletions
diff --git a/lib/CodeGen/CGClass.cpp b/lib/CodeGen/CGClass.cpp index a6ac0acfb9..c8f23f3f0c 100644 --- a/lib/CodeGen/CGClass.cpp +++ b/lib/CodeGen/CGClass.cpp @@ -14,6 +14,7 @@ #include "CGDebugInfo.h" #include "CodeGenFunction.h" #include "clang/AST/CXXInheritance.h" +#include "clang/AST/EvaluatedExprVisitor.h" #include "clang/AST/RecordLayout.h" #include "clang/AST/StmtCXX.h" @@ -334,6 +335,29 @@ namespace { CGF.EmitCXXDestructorCall(D, Dtor_Base, BaseIsVirtual, Addr); } }; + + /// A visitor which checks whether an initializer uses 'this' in a + /// way which requires the vtable to be properly set. + struct DynamicThisUseChecker : EvaluatedExprVisitor<DynamicThisUseChecker> { + typedef EvaluatedExprVisitor<DynamicThisUseChecker> super; + + bool UsesThis; + + DynamicThisUseChecker(ASTContext &C) : super(C), UsesThis(false) {} + + // Black-list all explicit and implicit references to 'this'. + // + // Do we need to worry about external references to 'this' derived + // from arbitrary code? If so, then anything which runs arbitrary + // external code might potentially access the vtable. + void VisitCXXThisExpr(CXXThisExpr *E) { UsesThis = true; } + }; +} + +static bool BaseInitializerUsesThis(ASTContext &C, const Expr *Init) { + DynamicThisUseChecker Checker(C); + Checker.Visit(const_cast<Expr*>(Init)); + return Checker.UsesThis; } static void EmitBaseInitializer(CodeGenFunction &CGF, @@ -355,6 +379,12 @@ static void EmitBaseInitializer(CodeGenFunction &CGF, if (CtorType == Ctor_Base && isBaseVirtual) return; + // If the initializer for the base (other than the constructor + // itself) accesses 'this' in any way, we need to initialize the + // vtables. + if (BaseInitializerUsesThis(CGF.getContext(), BaseInit->getInit())) + CGF.InitializeVTablePointers(ClassDecl); + // We can pretend to be a complete class because it only matters for // virtual bases, and we only do virtual bases for complete ctors. llvm::Value *V = diff --git a/test/CodeGenCXX/constructor-init.cpp b/test/CodeGenCXX/constructor-init.cpp index 284b8b5938..d610fd5ad8 100644 --- a/test/CodeGenCXX/constructor-init.cpp +++ b/test/CodeGenCXX/constructor-init.cpp @@ -81,6 +81,38 @@ void f() { // CHECK: ret void } +// Make sure we initialize the vtable pointer if it's required by a +// base initializer. +namespace InitVTable { + struct A { A(int); }; + struct B : A { + virtual int foo(); + B(); + B(int); + }; + + // CHECK: define void @_ZN10InitVTable1BC2Ev( + // CHECK: [[T0:%.*]] = bitcast [[B:%.*]]* [[THIS:%.*]] to i8*** + // CHECK-NEXT: store i8** getelementptr inbounds ([3 x i8*]* @_ZTVN10InitVTable1BE, i64 0, i64 2), i8*** [[T0]] + // CHECK: [[VTBL:%.*]] = load i32 ([[B]]*)*** {{%.*}} + // CHECK-NEXT: [[FNP:%.*]] = getelementptr inbounds i32 ([[B]]*)** [[VTBL]], i64 0 + // CHECK-NEXT: [[FN:%.*]] = load i32 ([[B]]*)** [[FNP]] + // CHECK-NEXT: [[ARG:%.*]] = call i32 [[FN]]([[B]]* [[THIS]]) + // CHECK-NEXT: call void @_ZN10InitVTable1AC2Ei({{.*}}* %1, i32 [[ARG]]) + // CHECK-NEXT: [[T0:%.*]] = bitcast [[B]]* [[THIS]] to i8*** + // CHECK-NEXT: store i8** getelementptr inbounds ([3 x i8*]* @_ZTVN10InitVTable1BE, i64 0, i64 2), i8*** [[T0]] + // CHECK-NEXT: ret void + B::B() : A(foo()) {} + + // CHECK: define void @_ZN10InitVTable1BC2Ei( + // CHECK: [[ARG:%.*]] = add nsw i32 {{%.*}}, 5 + // CHECK-NEXT: call void @_ZN10InitVTable1AC2Ei({{.*}}* {{%.*}}, i32 [[ARG]]) + // CHECK-NEXT: [[T0:%.*]] = bitcast [[B]]* {{%.*}} to i8*** + // CHECK-NEXT: store i8** getelementptr inbounds ([3 x i8*]* @_ZTVN10InitVTable1BE, i64 0, i64 2), i8*** [[T0]] + // CHECK-NEXT: ret void + B::B(int x) : A(x + 5) {} +} + template<typename T> struct X { X(const X &); |