MS ABI: Insert copy-constructors into the CatchableType

Find all unambiguous public classes of the exception object's class type
and reference all of their copy constructors.  Yes, this is not
conforming but it is necessary in order to implement their ABI.  This is
because the copy constructor is actually referenced by the metadata
describing which catch handlers are eligible to handle the exception
object.

N.B.  This doesn't yet handle the copy constructor closure case yet,
that work is ongoing.

Differential Revision: http://reviews.llvm.org/D8101

llvm-svn: 231499

clang/include/clang/AST/ASTContext.h

@@ -2193,6 +2193,12 @@ public:
   /// it is not used.
   bool DeclMustBeEmitted(const Decl *D);
 
+  const CXXConstructorDecl *
+  getCopyConstructorForExceptionObject(CXXRecordDecl *RD);
+
+  void addCopyConstructorForExceptionObject(CXXRecordDecl *RD,
+                                            CXXConstructorDecl *CD);
+
   void setManglingNumber(const NamedDecl *ND, unsigned Number);
   unsigned getManglingNumber(const NamedDecl *ND) const;
 

clang/include/clang/AST/Mangle.h

@@ -203,8 +203,8 @@ public:
   virtual void mangleCXXCatchableTypeArray(QualType T, uint32_t NumEntries,
                                            raw_ostream &Out) = 0;
 
-  virtual void mangleCXXCatchableType(QualType T, uint32_t Size,
-                                      raw_ostream &Out) = 0;
+  virtual void mangleCXXCatchableType(QualType T, const CXXConstructorDecl *CD,
+                                      uint32_t Size, raw_ostream &Out) = 0;
 
   virtual void mangleCXXRTTIBaseClassDescriptor(
       const CXXRecordDecl *Derived, uint32_t NVOffset, int32_t VBPtrOffset,

clang/lib/AST/ASTContext.cpp

@@ -8189,6 +8189,19 @@ MangleNumberingContext *ASTContext::createMangleNumberingContext() const {
   return ABI->createMangleNumberingContext();
 }
 
+const CXXConstructorDecl *
+ASTContext::getCopyConstructorForExceptionObject(CXXRecordDecl *RD) {
+  return ABI->getCopyConstructorForExceptionObject(
+      cast<CXXRecordDecl>(RD->getFirstDecl()));
+}
+
+void ASTContext::addCopyConstructorForExceptionObject(CXXRecordDecl *RD,
+                                                      CXXConstructorDecl *CD) {
+  return ABI->addCopyConstructorForExceptionObject(
+      cast<CXXRecordDecl>(RD->getFirstDecl()),
+      cast<CXXConstructorDecl>(CD->getFirstDecl()));
+}
+
 void ASTContext::setParameterIndex(const ParmVarDecl *D, unsigned int index) {
   ParamIndices[D] = index;
 }

clang/lib/AST/CXXABI.h

@@ -20,6 +20,7 @@
 namespace clang {
 
 class ASTContext;
+class CXXConstructorDecl;
 class MemberPointerType;
 class MangleNumberingContext;
 
@@ -41,6 +42,14 @@ public:
 
   /// Returns a new mangling number context for this C++ ABI.
   virtual MangleNumberingContext *createMangleNumberingContext() const = 0;
+
+  /// Adds a mapping from class to copy constructor for this C++ ABI.
+  virtual void addCopyConstructorForExceptionObject(CXXRecordDecl *,
+                                                    CXXConstructorDecl *) = 0;
+
+  /// Retrieves the mapping from class to copy constructor for this C++ ABI.
+  virtual const CXXConstructorDecl *
+  getCopyConstructorForExceptionObject(CXXRecordDecl *) = 0;
 };
 
 /// Creates an instance of a C++ ABI class.

clang/lib/AST/ItaniumCXXABI.cpp

@@ -133,6 +133,14 @@ public:
     return Layout.getNonVirtualSize() == PointerSize;
   }
 
+  const CXXConstructorDecl *
+  getCopyConstructorForExceptionObject(CXXRecordDecl *RD) override {
+    return nullptr;
+  }
+
+  void addCopyConstructorForExceptionObject(CXXRecordDecl *RD,
+                                            CXXConstructorDecl *CD) override {}
+
   MangleNumberingContext *createMangleNumberingContext() const override {
     return new ItaniumNumberingContext();
   }

clang/lib/AST/MicrosoftCXXABI.cpp

@@ -63,6 +63,8 @@ public:
 
 class MicrosoftCXXABI : public CXXABI {
   ASTContext &Context;
+  llvm::SmallDenseMap<CXXRecordDecl *, CXXConstructorDecl *> RecordToCopyCtor;
+
 public:
   MicrosoftCXXABI(ASTContext &Ctx) : Context(Ctx) { }
 
@@ -82,13 +84,26 @@ public:
       return false;
 
     const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
-    
+
     // In the Microsoft ABI, classes can have one or two vtable pointers.
-    CharUnits PointerSize = 
-      Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
+    CharUnits PointerSize =
+        Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
     return Layout.getNonVirtualSize() == PointerSize ||
       Layout.getNonVirtualSize() == PointerSize * 2;
-  }    
+  }
+
+  const CXXConstructorDecl *
+  getCopyConstructorForExceptionObject(CXXRecordDecl *RD) override {
+    return RecordToCopyCtor[RD];
+  }
+
+  void
+  addCopyConstructorForExceptionObject(CXXRecordDecl *RD,
+                                       CXXConstructorDecl *CD) override {
+    assert(CD != nullptr);
+    assert(RecordToCopyCtor[RD] == nullptr || RecordToCopyCtor[RD] == CD);
+    RecordToCopyCtor[RD] = CD;
+  }
 
   MangleNumberingContext *createMangleNumberingContext() const override {
     return new MicrosoftNumberingContext();

clang/lib/AST/MicrosoftMangle.cpp

@@ -114,8 +114,8 @@ public:
                           uint32_t NumEntries, raw_ostream &Out) override;
   void mangleCXXCatchableTypeArray(QualType T, uint32_t NumEntries,
                                    raw_ostream &Out) override;
-  void mangleCXXCatchableType(QualType T, uint32_t Size,
-                              raw_ostream &Out) override;
+  void mangleCXXCatchableType(QualType T, const CXXConstructorDecl *CD,
+                              uint32_t Size, raw_ostream &Out) override;
   void mangleCXXRTTI(QualType T, raw_ostream &Out) override;
   void mangleCXXRTTIName(QualType T, raw_ostream &Out) override;
   void mangleCXXRTTIBaseClassDescriptor(const CXXRecordDecl *Derived,
@@ -2307,13 +2307,25 @@ void MicrosoftMangleContextImpl::mangleCXXCatchableTypeArray(
   Mangler.mangleType(T, SourceRange(), MicrosoftCXXNameMangler::QMM_Result);
 }
 
-void MicrosoftMangleContextImpl::mangleCXXCatchableType(QualType T,
-                                                        uint32_t Size,
-                                                        raw_ostream &Out) {
+void MicrosoftMangleContextImpl::mangleCXXCatchableType(
+    QualType T, const CXXConstructorDecl *CD, uint32_t Size, raw_ostream &Out) {
   MicrosoftCXXNameMangler Mangler(*this, Out);
-  Mangler.getStream() << "_CT??_R0";
-  Mangler.mangleType(T, SourceRange(), MicrosoftCXXNameMangler::QMM_Result);
-  Mangler.getStream() << "@8";
+  Mangler.getStream() << "_CT";
+
+  llvm::SmallString<64> RTTIMangling;
+  {
+    llvm::raw_svector_ostream Stream(RTTIMangling);
+    mangleCXXRTTI(T, Stream);
+  }
+  Mangler.getStream() << RTTIMangling.substr(1);
+
+  llvm::SmallString<64> CopyCtorMangling;
+  if (CD) {
+    llvm::raw_svector_ostream Stream(CopyCtorMangling);
+    mangleCXXCtor(CD, Ctor_Complete, Stream);
+  }
+  Mangler.getStream() << CopyCtorMangling.substr(1);
+
   Mangler.getStream() << Size;
 }
 

clang/lib/CodeGen/MicrosoftCXXABI.cpp

@@ -17,6 +17,7 @@
 #include "CGCXXABI.h"
 #include "CGVTables.h"
 #include "CodeGenModule.h"
+#include "CodeGenTypes.h"
 #include "TargetInfo.h"
 #include "clang/AST/Decl.h"
 #include "clang/AST/DeclCXX.h"
@@ -3225,11 +3226,14 @@ llvm::Constant *MicrosoftCXXABI::getCatchableType(QualType T,
                                                   uint32_t VBIndex) {
   assert(!T->isReferenceType());
 
+  CXXRecordDecl *RD = T->getAsCXXRecordDecl();
+  const CXXConstructorDecl *CD =
+      RD ? CGM.getContext().getCopyConstructorForExceptionObject(RD) : nullptr;
   uint32_t Size = getContext().getTypeSizeInChars(T).getQuantity();
   SmallString<256> MangledName;
   {
     llvm::raw_svector_ostream Out(MangledName);
-    getMangleContext().mangleCXXCatchableType(T, Size, Out);
+    getMangleContext().mangleCXXCatchableType(T, CD, Size, Out);
   }
   if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(MangledName))
     return getImageRelativeConstant(GV);
@@ -3241,16 +3245,15 @@ llvm::Constant *MicrosoftCXXABI::getCatchableType(QualType T,
   // The runtime is responsible for calling the copy constructor if the
   // exception is caught by value.
   llvm::Constant *CopyCtor =
-      getImageRelativeConstant(llvm::Constant::getNullValue(CGM.Int8PtrTy));
+      CD ? llvm::ConstantExpr::getBitCast(
+               CGM.getAddrOfCXXStructor(CD, StructorType::Complete),
+               CGM.Int8PtrTy)
+         : llvm::Constant::getNullValue(CGM.Int8PtrTy);
+  CopyCtor = getImageRelativeConstant(CopyCtor);
 
-  bool IsScalar = true;
+  bool IsScalar = !RD;
   bool HasVirtualBases = false;
   bool IsStdBadAlloc = false; // std::bad_alloc is special for some reason.
-  if (T->getAsCXXRecordDecl()) {
-    IsScalar = false;
-    // TODO: Fill in the CopyCtor here!  This is not trivial due to
-    // copy-constructors possessing things like default arguments.
-  }
   QualType PointeeType = T;
   if (T->isPointerType())
     PointeeType = T->getPointeeType();

clang/lib/Sema/SemaExprCXX.cpp

@@ -657,6 +657,55 @@ ExprResult Sema::BuildCXXThrow(SourceLocation OpLoc, Expr *Ex,
       CXXThrowExpr(Ex, Context.VoidTy, OpLoc, IsThrownVarInScope);
 }
 
+static void
+collectPublicBases(CXXRecordDecl *RD,
+                   llvm::DenseMap<CXXRecordDecl *, unsigned> &SubobjectsSeen,
+                   llvm::SmallPtrSetImpl<CXXRecordDecl *> &VBases,
+                   llvm::SetVector<CXXRecordDecl *> &PublicSubobjectsSeen,
+                   bool ParentIsPublic) {
+  for (const CXXBaseSpecifier &BS : RD->bases()) {
+    CXXRecordDecl *BaseDecl = BS.getType()->getAsCXXRecordDecl();
+    bool NewSubobject;
+    // Virtual bases constitute the same subobject.  Non-virtual bases are
+    // always distinct subobjects.
+    if (BS.isVirtual())
+      NewSubobject = VBases.insert(BaseDecl).second;
+    else
+      NewSubobject = true;
+
+    if (NewSubobject)
+      ++SubobjectsSeen[BaseDecl];
+
+    // Only add subobjects which have public access throughout the entire chain.
+    bool PublicPath = ParentIsPublic && BS.getAccessSpecifier() == AS_public;
+    if (PublicPath)
+      PublicSubobjectsSeen.insert(BaseDecl);
+
+    // Recurse on to each base subobject.
+    collectPublicBases(BaseDecl, SubobjectsSeen, VBases, PublicSubobjectsSeen,
+                       PublicPath);
+  }
+}
+
+static void getUnambiguousPublicSubobjects(
+    CXXRecordDecl *RD, llvm::SmallVectorImpl<CXXRecordDecl *> &Objects) {
+  llvm::DenseMap<CXXRecordDecl *, unsigned> SubobjectsSeen;
+  llvm::SmallSet<CXXRecordDecl *, 2> VBases;
+  llvm::SetVector<CXXRecordDecl *> PublicSubobjectsSeen;
+  SubobjectsSeen[RD] = 1;
+  PublicSubobjectsSeen.insert(RD);
+  collectPublicBases(RD, SubobjectsSeen, VBases, PublicSubobjectsSeen,
+                     /*ParentIsPublic=*/true);
+
+  for (CXXRecordDecl *PublicSubobject : PublicSubobjectsSeen) {
+    // Skip ambiguous objects.
+    if (SubobjectsSeen[PublicSubobject] > 1)
+      continue;
+
+    Objects.push_back(PublicSubobject);
+  }
+}
+
 /// CheckCXXThrowOperand - Validate the operand of a throw.
 ExprResult Sema::CheckCXXThrowOperand(SourceLocation ThrowLoc, Expr *E,
                                       bool IsThrownVarInScope) {
@@ -723,18 +772,29 @@ ExprResult Sema::CheckCXXThrowOperand(SourceLocation ThrowLoc, Expr *E,
     return E;
 
   // If the class has a destructor, we must be able to call it.
-  if (RD->hasIrrelevantDestructor())
-    return E;
+  if (!RD->hasIrrelevantDestructor()) {
+    if (CXXDestructorDecl *Destructor = LookupDestructor(RD)) {
+      MarkFunctionReferenced(E->getExprLoc(), Destructor);
+      CheckDestructorAccess(E->getExprLoc(), Destructor,
+                            PDiag(diag::err_access_dtor_exception) << Ty);
+      if (DiagnoseUseOfDecl(Destructor, E->getExprLoc()))
+        return ExprError();
+    }
+  }
 
-  CXXDestructorDecl *Destructor = LookupDestructor(RD);
-  if (!Destructor)
-    return E;
+  if (Context.getTargetInfo().getCXXABI().isMicrosoft()) {
+    llvm::SmallVector<CXXRecordDecl *, 2> UnambiguousPublicSubobjects;
+    getUnambiguousPublicSubobjects(RD, UnambiguousPublicSubobjects);
+    for (CXXRecordDecl *Subobject : UnambiguousPublicSubobjects) {
+      if (CXXConstructorDecl *CD = LookupCopyingConstructor(Subobject, 0)) {
+        if (CD->isTrivial())
+          continue;
+        MarkFunctionReferenced(E->getExprLoc(), CD);
+        Context.addCopyConstructorForExceptionObject(Subobject, CD);
+      }
+    }
+  }
 
-  MarkFunctionReferenced(E->getExprLoc(), Destructor);
-  CheckDestructorAccess(E->getExprLoc(), Destructor,
-                        PDiag(diag::err_access_dtor_exception) << Ty);
-  if (DiagnoseUseOfDecl(Destructor, E->getExprLoc()))
-    return ExprError();
   return E;
 }
 

clang/test/CodeGenCXX/microsoft-abi-throw.cpp

@@ -1,16 +1,16 @@
 // RUN: %clang_cc1 -emit-llvm -o - -triple=i386-pc-win32 %s -fcxx-exceptions | FileCheck %s
 
 // CHECK-DAG: @"\01??_R0?AUY@@@8" = linkonce_odr global %rtti.TypeDescriptor7 { i8** @"\01??_7type_info@@6B@", i8* null, [8 x i8] c".?AUY@@\00" }, comdat
-// CHECK-DAG: @"_CT??_R0?AUY@@@88" = linkonce_odr unnamed_addr constant %eh.CatchableType { i32 4, i8* bitcast (%rtti.TypeDescriptor7* @"\01??_R0?AUY@@@8" to i8*), i32 0, i32 -1, i32 0, i32 8, i8* null }, comdat
+// CHECK-DAG: @"_CT??_R0?AUY@@@8??0Y@@QAE@ABU0@@Z8" = linkonce_odr unnamed_addr constant %eh.CatchableType { i32 4, i8* bitcast (%rtti.TypeDescriptor7* @"\01??_R0?AUY@@@8" to i8*), i32 0, i32 -1, i32 0, i32 8, i8* bitcast (%struct.Y* (%struct.Y*, %struct.Y*, i32)* @"\01??0Y@@QAE@ABU0@@Z" to i8*) }, comdat
 // CHECK-DAG: @"\01??_R0?AUZ@@@8" = linkonce_odr global %rtti.TypeDescriptor7 { i8** @"\01??_7type_info@@6B@", i8* null, [8 x i8] c".?AUZ@@\00" }, comdat
 // CHECK-DAG: @"_CT??_R0?AUZ@@@81" = linkonce_odr unnamed_addr constant %eh.CatchableType { i32 0, i8* bitcast (%rtti.TypeDescriptor7* @"\01??_R0?AUZ@@@8" to i8*), i32 0, i32 -1, i32 0, i32 1, i8* null }, comdat
 // CHECK-DAG: @"\01??_R0?AUW@@@8" = linkonce_odr global %rtti.TypeDescriptor7 { i8** @"\01??_7type_info@@6B@", i8* null, [8 x i8] c".?AUW@@\00" }, comdat
-// CHECK-DAG: @"_CT??_R0?AUW@@@84" = linkonce_odr unnamed_addr constant %eh.CatchableType { i32 4, i8* bitcast (%rtti.TypeDescriptor7* @"\01??_R0?AUW@@@8" to i8*), i32 4, i32 -1, i32 0, i32 4, i8* null }, comdat
+// CHECK-DAG: @"_CT??_R0?AUW@@@8??0W@@QAE@ABU0@@Z4" = linkonce_odr unnamed_addr constant %eh.CatchableType { i32 4, i8* bitcast (%rtti.TypeDescriptor7* @"\01??_R0?AUW@@@8" to i8*), i32 4, i32 -1, i32 0, i32 4, i8* bitcast (%struct.W* (%struct.W*, %struct.W*, i32)* @"\01??0W@@QAE@ABU0@@Z" to i8*) }, comdat
 // CHECK-DAG: @"\01??_R0?AUM@@@8" = linkonce_odr global %rtti.TypeDescriptor7 { i8** @"\01??_7type_info@@6B@", i8* null, [8 x i8] c".?AUM@@\00" }, comdat
 // CHECK-DAG: @"_CT??_R0?AUM@@@81" = linkonce_odr unnamed_addr constant %eh.CatchableType { i32 0, i8* bitcast (%rtti.TypeDescriptor7* @"\01??_R0?AUM@@@8" to i8*), i32 8, i32 -1, i32 0, i32 1, i8* null }, comdat
 // CHECK-DAG: @"\01??_R0?AUV@@@8" = linkonce_odr global %rtti.TypeDescriptor7 { i8** @"\01??_7type_info@@6B@", i8* null, [8 x i8] c".?AUV@@\00" }, comdat
 // CHECK-DAG: @"_CT??_R0?AUV@@@81" = linkonce_odr unnamed_addr constant %eh.CatchableType { i32 0, i8* bitcast (%rtti.TypeDescriptor7* @"\01??_R0?AUV@@@8" to i8*), i32 0, i32 4, i32 4, i32 1, i8* null }, comdat
-// CHECK-DAG: @"_CTA5?AUY@@" = linkonce_odr unnamed_addr constant %eh.CatchableTypeArray.5 { i32 5, [5 x %eh.CatchableType*] [%eh.CatchableType* @"_CT??_R0?AUY@@@88", %eh.CatchableType* @"_CT??_R0?AUZ@@@81", %eh.CatchableType* @"_CT??_R0?AUW@@@84", %eh.CatchableType* @"_CT??_R0?AUM@@@81", %eh.CatchableType* @"_CT??_R0?AUV@@@81"] }, comdat
+// CHECK-DAG: @"_CTA5?AUY@@" = linkonce_odr unnamed_addr constant %eh.CatchableTypeArray.5 { i32 5, [5 x %eh.CatchableType*] [%eh.CatchableType* @"_CT??_R0?AUY@@@8??0Y@@QAE@ABU0@@Z8", %eh.CatchableType* @"_CT??_R0?AUZ@@@81", %eh.CatchableType* @"_CT??_R0?AUW@@@8??0W@@QAE@ABU0@@Z4", %eh.CatchableType* @"_CT??_R0?AUM@@@81", %eh.CatchableType* @"_CT??_R0?AUV@@@81"] }, comdat
 // CHECK-DAG: @"_TI5?AUY@@" = linkonce_odr unnamed_addr constant %eh.ThrowInfo { i32 0, i8* bitcast (void (%struct.Y*)* @"\01??_DY@@QAE@XZ" to i8*), i8* null, i8* bitcast (%eh.CatchableTypeArray.5* @"_CTA5?AUY@@" to i8*) }, comdat