Teach IR generation to return 'this' from constructors and destructors
under the ARM ABI.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@112588 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/ItaniumCXXABI.cpp b/lib/CodeGen/ItaniumCXXABI.cpp
index 354e72f..920b833 100644
--- a/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/lib/CodeGen/ItaniumCXXABI.cpp
@@ -87,11 +87,55 @@
llvm::Value *EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
llvm::Value *Addr,
const MemberPointerType *MPT);
+
+ void BuildConstructorSignature(const CXXConstructorDecl *Ctor,
+ CXXCtorType T,
+ CanQualType &ResTy,
+ llvm::SmallVectorImpl<CanQualType> &ArgTys);
+
+ void BuildDestructorSignature(const CXXDestructorDecl *Dtor,
+ CXXDtorType T,
+ CanQualType &ResTy,
+ llvm::SmallVectorImpl<CanQualType> &ArgTys);
+
+ void BuildInstanceFunctionParams(CodeGenFunction &CGF,
+ QualType &ResTy,
+ FunctionArgList &Params);
+
+ void EmitInstanceFunctionProlog(CodeGenFunction &CGF);
};
class ARMCXXABI : public ItaniumCXXABI {
public:
ARMCXXABI(CodeGen::CodeGenModule &CGM) : ItaniumCXXABI(CGM, /*ARM*/ true) {}
+
+ void BuildConstructorSignature(const CXXConstructorDecl *Ctor,
+ CXXCtorType T,
+ CanQualType &ResTy,
+ llvm::SmallVectorImpl<CanQualType> &ArgTys);
+
+ void BuildDestructorSignature(const CXXDestructorDecl *Dtor,
+ CXXDtorType T,
+ CanQualType &ResTy,
+ llvm::SmallVectorImpl<CanQualType> &ArgTys);
+
+ void BuildInstanceFunctionParams(CodeGenFunction &CGF,
+ QualType &ResTy,
+ FunctionArgList &Params);
+
+ void EmitInstanceFunctionProlog(CodeGenFunction &CGF);
+
+ void EmitReturnFromThunk(CodeGenFunction &CGF, RValue RV, QualType ResTy);
+
+
+private:
+ /// \brief Returns true if the given instance method is one of the
+ /// kinds that the ARM ABI says returns 'this'.
+ static bool HasThisReturn(GlobalDecl GD) {
+ const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
+ return ((isa<CXXDestructorDecl>(MD) && GD.getDtorType() != Dtor_Deleting) ||
+ (isa<CXXConstructorDecl>(MD)));
+ }
};
}
@@ -586,3 +630,120 @@
bool ItaniumCXXABI::isZeroInitializable(const MemberPointerType *MPT) {
return MPT->getPointeeType()->isFunctionType();
}
+
+/// The generic ABI passes 'this', plus a VTT if it's initializing a
+/// base subobject.
+void ItaniumCXXABI::BuildConstructorSignature(const CXXConstructorDecl *Ctor,
+ CXXCtorType Type,
+ CanQualType &ResTy,
+ llvm::SmallVectorImpl<CanQualType> &ArgTys) {
+ ASTContext &Context = CGM.getContext();
+
+ // 'this' is already there.
+
+ // Check if we need to add a VTT parameter (which has type void **).
+ if (Type == Ctor_Base && Ctor->getParent()->getNumVBases() != 0)
+ ArgTys.push_back(Context.getPointerType(Context.VoidPtrTy));
+}
+
+/// The ARM ABI does the same as the Itanium ABI, but returns 'this'.
+void ARMCXXABI::BuildConstructorSignature(const CXXConstructorDecl *Ctor,
+ CXXCtorType Type,
+ CanQualType &ResTy,
+ llvm::SmallVectorImpl<CanQualType> &ArgTys) {
+ ItaniumCXXABI::BuildConstructorSignature(Ctor, Type, ResTy, ArgTys);
+ ResTy = ArgTys[0];
+}
+
+/// The generic ABI passes 'this', plus a VTT if it's destroying a
+/// base subobject.
+void ItaniumCXXABI::BuildDestructorSignature(const CXXDestructorDecl *Dtor,
+ CXXDtorType Type,
+ CanQualType &ResTy,
+ llvm::SmallVectorImpl<CanQualType> &ArgTys) {
+ ASTContext &Context = CGM.getContext();
+
+ // 'this' is already there.
+
+ // Check if we need to add a VTT parameter (which has type void **).
+ if (Type == Dtor_Base && Dtor->getParent()->getNumVBases() != 0)
+ ArgTys.push_back(Context.getPointerType(Context.VoidPtrTy));
+}
+
+/// The ARM ABI does the same as the Itanium ABI, but returns 'this'
+/// for non-deleting destructors.
+void ARMCXXABI::BuildDestructorSignature(const CXXDestructorDecl *Dtor,
+ CXXDtorType Type,
+ CanQualType &ResTy,
+ llvm::SmallVectorImpl<CanQualType> &ArgTys) {
+ ItaniumCXXABI::BuildDestructorSignature(Dtor, Type, ResTy, ArgTys);
+
+ if (Type != Dtor_Deleting)
+ ResTy = ArgTys[0];
+}
+
+void ItaniumCXXABI::BuildInstanceFunctionParams(CodeGenFunction &CGF,
+ QualType &ResTy,
+ FunctionArgList &Params) {
+ /// Create the 'this' variable.
+ BuildThisParam(CGF, Params);
+
+ const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());
+ assert(MD->isInstance());
+
+ // Check if we need a VTT parameter as well.
+ if (CodeGenVTables::needsVTTParameter(CGF.CurGD)) {
+ ASTContext &Context = CGF.getContext();
+
+ // FIXME: avoid the fake decl
+ QualType T = Context.getPointerType(Context.VoidPtrTy);
+ ImplicitParamDecl *VTTDecl
+ = ImplicitParamDecl::Create(Context, 0, MD->getLocation(),
+ &Context.Idents.get("vtt"), T);
+ Params.push_back(std::make_pair(VTTDecl, VTTDecl->getType()));
+ getVTTDecl(CGF) = VTTDecl;
+ }
+}
+
+void ARMCXXABI::BuildInstanceFunctionParams(CodeGenFunction &CGF,
+ QualType &ResTy,
+ FunctionArgList &Params) {
+ ItaniumCXXABI::BuildInstanceFunctionParams(CGF, ResTy, Params);
+
+ // Return 'this' from certain constructors and destructors.
+ if (HasThisReturn(CGF.CurGD))
+ ResTy = Params[0].second;
+}
+
+void ItaniumCXXABI::EmitInstanceFunctionProlog(CodeGenFunction &CGF) {
+ /// Initialize the 'this' slot.
+ EmitThisParam(CGF);
+
+ /// Initialize the 'vtt' slot if needed.
+ if (getVTTDecl(CGF)) {
+ getVTTValue(CGF)
+ = CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(getVTTDecl(CGF)),
+ "vtt");
+ }
+}
+
+void ARMCXXABI::EmitInstanceFunctionProlog(CodeGenFunction &CGF) {
+ ItaniumCXXABI::EmitInstanceFunctionProlog(CGF);
+
+ /// Initialize the return slot to 'this' at the start of the
+ /// function.
+ if (HasThisReturn(CGF.CurGD))
+ CGF.Builder.CreateStore(CGF.LoadCXXThis(), CGF.ReturnValue);
+}
+
+void ARMCXXABI::EmitReturnFromThunk(CodeGenFunction &CGF,
+ RValue RV, QualType ResultType) {
+ if (!isa<CXXDestructorDecl>(CGF.CurGD.getDecl()))
+ return ItaniumCXXABI::EmitReturnFromThunk(CGF, RV, ResultType);
+
+ // Destructor thunks in the ARM ABI have indeterminate results.
+ const llvm::Type *T =
+ cast<llvm::PointerType>(CGF.ReturnValue->getType())->getElementType();
+ RValue Undef = RValue::get(llvm::UndefValue::get(T));
+ return ItaniumCXXABI::EmitReturnFromThunk(CGF, Undef, ResultType);
+}