Abstract out parts of thunk emission code, add support for simple thunks when using -cxx-abi microsoft

Reviewed at http://llvm-reviews.chandlerc.com/D1787

llvm-svn: 192220

7 files changed, 172 insertions, 75 deletions

diff --git a/clang/lib/AST/MicrosoftMangle.cpp b/clang/lib/AST/MicrosoftMangle.cpp
index ab0db1acbf6..2c37709bcf1 100644
--- a/clang/lib/AST/MicrosoftMangle.cpp
+++ b/clang/lib/AST/MicrosoftMangle.cpp
@@ -15,6 +15,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Attr.h"
 #include "clang/AST/CharUnits.h"
+#include "clang/AST/CXXInheritance.h"
 #include "clang/AST/Decl.h"
 #include "clang/AST/DeclCXX.h"
 #include "clang/AST/DeclObjC.h"
@@ -1405,7 +1406,8 @@ void MicrosoftCXXNameMangler::mangleFunctionClass(const FunctionDecl *FD) {
   //                   ::= Z # global far
   if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) {
     switch (MD->getAccess()) {
-      default:
+      case AS_none:
+        llvm_unreachable("Unsupported access specifier");
       case AS_private:
         if (MD->isStatic())
           Out << 'C';
@@ -1858,36 +1860,70 @@ void MicrosoftMangleContextImpl::mangleName(const NamedDecl *D,
   return Mangler.mangle(D);
 }
 
+static void mangleThunkThisAdjustment(const CXXMethodDecl *MD,
+                                      const ThisAdjustment &Adjustment,
+                                      MicrosoftCXXNameMangler &Mangler,
+                                      raw_ostream &Out) {
+  // FIXME: add support for vtordisp thunks.
+  if (Adjustment.NonVirtual != 0) {
+    switch (MD->getAccess()) {
+    case AS_none:
+      llvm_unreachable("Unsupported access specifier");
+    case AS_private:
+      Out << 'G';
+      break;
+    case AS_protected:
+      Out << 'O';
+      break;
+    case AS_public:
+      Out << 'W';
+    }
+    llvm::APSInt APSNumber(/*BitWidth=*/32, /*isUnsigned=*/true);
+    APSNumber = -Adjustment.NonVirtual;
+    Mangler.mangleNumber(APSNumber);
+  } else {
+    switch (MD->getAccess()) {
+    case AS_none:
+      llvm_unreachable("Unsupported access specifier");
+    case AS_private:
+      Out << 'A';
+      break;
+    case AS_protected:
+      Out << 'I';
+      break;
+    case AS_public:
+      Out << 'Q';
+    }
+  }
+}
+
 void MicrosoftMangleContextImpl::mangleThunk(const CXXMethodDecl *MD,
                                              const ThunkInfo &Thunk,
                                              raw_ostream &Out) {
-  // FIXME: this is not yet a complete implementation, but merely a
-  // reasonably-working stub to avoid crashing when required to emit a thunk.
   MicrosoftCXXNameMangler Mangler(*this, Out);
   Out << "\01?";
   Mangler.mangleName(MD);
-  if (Thunk.This.NonVirtual != 0) {
-    // FIXME: add support for protected/private or use mangleFunctionClass.
-    Out << "W";
-    llvm::APSInt APSNumber(/*BitWidth=*/32 /*FIXME: check on x64*/,
-                           /*isUnsigned=*/true);
-    APSNumber = -Thunk.This.NonVirtual;
-    Mangler.mangleNumber(APSNumber);
-  } else {
-    // FIXME: add support for protected/private or use mangleFunctionClass.
-    Out << "Q";
-  }
-  // FIXME: mangle return adjustment? Most likely includes using an overridee FPT?
-  Mangler.mangleFunctionType(MD->getType()->castAs<FunctionProtoType>(), MD);
-}
-
-void MicrosoftMangleContextImpl::mangleCXXDtorThunk(const CXXDestructorDecl *DD,
-                                                    CXXDtorType Type,
-                                                    const ThisAdjustment &,
-                                                    raw_ostream &) {
-  unsigned DiagID = getDiags().getCustomDiagID(DiagnosticsEngine::Error,
-    "cannot mangle thunk for this destructor yet");
-  getDiags().Report(DD->getLocation(), DiagID);
+  mangleThunkThisAdjustment(MD, Thunk.This, Mangler, Out);
+  if (!Thunk.Return.isEmpty())
+    assert(Thunk.Method != 0 && "Thunk info should hold the overridee decl");
+
+  const CXXMethodDecl *DeclForFPT = Thunk.Method ? Thunk.Method : MD;
+  Mangler.mangleFunctionType(
+      DeclForFPT->getType()->castAs<FunctionProtoType>(), MD);
+}
+
+void MicrosoftMangleContextImpl::mangleCXXDtorThunk(
+    const CXXDestructorDecl *DD, CXXDtorType Type,
+    const ThisAdjustment &Adjustment, raw_ostream &Out) {
+  // FIXME: Actually, the dtor thunk should be emitted for vector deleting
+  // dtors rather than scalar deleting dtors. Just use the vector deleting dtor
+  // mangling manually until we support both deleting dtor types.
+  assert(Type == Dtor_Deleting);
+  MicrosoftCXXNameMangler Mangler(*this, Out, DD, Type);
+  Out << "\01??_E";
+  Mangler.mangleName(DD->getParent());
+  mangleThunkThisAdjustment(DD, Adjustment, Mangler, Out);
+  Mangler.mangleFunctionType(DD->getType()->castAs<FunctionProtoType>(), DD);
 }
 
 void MicrosoftMangleContextImpl::mangleCXXVFTable(
diff --git a/clang/lib/AST/VTableBuilder.cpp b/clang/lib/AST/VTableBuilder.cpp
index 9aad711748c..fbc5e3dd93a 100644
--- a/clang/lib/AST/VTableBuilder.cpp
+++ b/clang/lib/AST/VTableBuilder.cpp
@@ -992,6 +992,7 @@ public:
     MostDerivedClassIsVirtual(MostDerivedClassIsVirtual), 
     LayoutClass(LayoutClass), Context(MostDerivedClass->getASTContext()), 
     Overriders(MostDerivedClass, MostDerivedClassOffset, LayoutClass) {
+    assert(!Context.getTargetInfo().getCXXABI().isMicrosoft());
 
     LayoutVTable();
 
@@ -1904,6 +1905,21 @@ VTableBuilder::LayoutVTablesForVirtualBases(const CXXRecordDecl *RD,
   }
 }
 
+struct ItaniumThunkInfoComparator {
+  bool operator() (const ThunkInfo &LHS, const ThunkInfo &RHS) {
+    assert(LHS.Method == 0);
+    assert(RHS.Method == 0);
+
+    if (LHS.This != RHS.This)
+      return LHS.This < RHS.This;
+
+    if (LHS.Return != RHS.Return)
+      return LHS.Return < RHS.Return;
+
+    llvm_unreachable("Shouldn't observe two equal thunks");
+  }
+};
+
 /// dumpLayout - Dump the vtable layout.
 void VTableBuilder::dumpLayout(raw_ostream& Out) {
   // FIXME: write more tests that actually use the dumpLayout output to prevent
@@ -2146,7 +2162,8 @@ void VTableBuilder::dumpLayout(raw_ostream& Out) {
       const CXXMethodDecl *MD = I->second;
 
       ThunkInfoVectorTy ThunksVector = Thunks[MD];
-      std::sort(ThunksVector.begin(), ThunksVector.end());
+      std::sort(ThunksVector.begin(), ThunksVector.end(),
+                ItaniumThunkInfoComparator());
 
       Out << "Thunks for '" << MethodName << "' (" << ThunksVector.size();
       Out << (ThunksVector.size() == 1 ? " entry" : " entries") << ").\n";
@@ -2233,7 +2250,15 @@ void VTableBuilder::dumpLayout(raw_ostream& Out) {
 
   Out << '\n';
 }
-  
+
+struct VTableThunksComparator {
+  bool operator()(const VTableLayout::VTableThunkTy &LHS,
+                  const VTableLayout::VTableThunkTy &RHS) {
+    assert(LHS.first != RHS.first &&
+            "All thunks should have unique indices!");
+    return LHS.first < RHS.first;
+  }
+};
 }
 
 VTableLayout::VTableLayout(uint64_t NumVTableComponents,
@@ -2252,6 +2277,9 @@ VTableLayout::VTableLayout(uint64_t NumVTableComponents,
             this->VTableComponents.get());
   std::copy(VTableThunks, VTableThunks+NumVTableThunks,
             this->VTableThunks.get());
+  std::sort(this->VTableThunks.get(),
+            this->VTableThunks.get() + NumVTableThunks,
+            VTableThunksComparator());
 }
 
 VTableLayout::~VTableLayout() { }
@@ -2312,7 +2340,6 @@ VTableContext::getVirtualBaseOffsetOffset(const CXXRecordDecl *RD,
 static VTableLayout *CreateVTableLayout(const VTableBuilder &Builder) {
   SmallVector<VTableLayout::VTableThunkTy, 1>
     VTableThunks(Builder.vtable_thunks_begin(), Builder.vtable_thunks_end());
-  std::sort(VTableThunks.begin(), VTableThunks.end());
 
   return new VTableLayout(Builder.getNumVTableComponents(),
                           Builder.vtable_component_begin(),
@@ -2520,18 +2547,14 @@ private:
 
   /// AddMethod - Add a single virtual member function to the vftable
   /// components vector.
-  void AddMethod(const CXXMethodDecl *MD, ThisAdjustment ThisAdjustment,
-                 ReturnAdjustment ReturnAdjustment) {
+  void AddMethod(const CXXMethodDecl *MD, ThunkInfo TI) {
     if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
-      assert(ReturnAdjustment.isEmpty() &&
+      assert(TI.Return.isEmpty() &&
              "Destructor can't have return adjustment!");
       Components.push_back(VTableComponent::MakeDeletingDtor(DD));
     } else {
-      // Add the return adjustment if necessary.
-      if (!ReturnAdjustment.isEmpty() || !ThisAdjustment.isEmpty()) {
-        VTableThunks[Components.size()].Return = ReturnAdjustment;
-        VTableThunks[Components.size()].This = ThisAdjustment;
-      }
+      if (!TI.isEmpty())
+        VTableThunks[Components.size()] = TI;
       Components.push_back(VTableComponent::MakeFunction(MD));
     }
   }
@@ -2816,6 +2839,7 @@ void VFTableBuilder::AddMethods(BaseSubobject Base, unsigned BaseDepth,
     FinalOverriders::OverriderInfo Overrider =
         Overriders.getOverrider(MD, Base.getBaseOffset());
     ThisAdjustment ThisAdjustmentOffset;
+    bool ForceThunk = false;
 
     // Check if this virtual member function overrides
     // a method in one of the visited bases.
@@ -2840,8 +2864,7 @@ void VFTableBuilder::AddMethods(BaseSubobject Base, unsigned BaseDepth,
         AddThunk(MD, VTableThunks[OverriddenMethodInfo.VFTableIndex]);
       }
 
-      if (ComputeReturnAdjustmentBaseOffset(Context, MD, OverriddenMD)
-              .isEmpty()) {
+      if (MD->getResultType() == OverriddenMD->getResultType()) {
         // No return adjustment needed - just replace the overridden method info
         // with the current info.
         MethodInfo MI(OverriddenMethodInfo.VBTableIndex,
@@ -2859,6 +2882,7 @@ void VFTableBuilder::AddMethods(BaseSubobject Base, unsigned BaseDepth,
         // method was in the vftable.
         // For now, just mark the overriden method as shadowed by a new slot.
         OverriddenMethodInfo.Shadowed = true;
+        ForceThunk = true;
 
         // Also apply this adjustment to the shadowed slots.
         if (!ThisAdjustmentOffset.isEmpty()) {
@@ -2907,6 +2931,7 @@ void VFTableBuilder::AddMethods(BaseSubobject Base, unsigned BaseDepth,
           ComputeReturnAdjustmentBaseOffset(Context, OverriderMD, MD);
     }
     if (!ReturnAdjustmentOffset.isEmpty()) {
+      ForceThunk = true;
       ReturnAdjustment.NonVirtual =
           ReturnAdjustmentOffset.NonVirtualOffset.getQuantity();
       if (ReturnAdjustmentOffset.VirtualBase) {
@@ -2918,7 +2943,8 @@ void VFTableBuilder::AddMethods(BaseSubobject Base, unsigned BaseDepth,
       }
     }
 
-    AddMethod(Overrider.Method, ThisAdjustmentOffset, ReturnAdjustment);
+    AddMethod(OverriderMD, ThunkInfo(ThisAdjustmentOffset, ReturnAdjustment,
+                                     ForceThunk ? MD : 0));
   }
 }
 
@@ -2929,6 +2955,20 @@ void PrintBasePath(const VFPtrInfo::BasePath &Path, raw_ostream &Out) {
   }
 }
 
+struct MicrosoftThunkInfoStableSortComparator {
+  bool operator() (const ThunkInfo &LHS, const ThunkInfo &RHS) {
+    if (LHS.This != RHS.This)
+      return LHS.This < RHS.This;
+
+    if (LHS.Return != RHS.Return)
+      return LHS.Return < RHS.Return;
+
+    // Keep different thunks with the same adjustments in the order they
+    // were put into the vector.
+    return false;
+  }
+};
+
 void VFTableBuilder::dumpLayout(raw_ostream &Out) {
   Out << "VFTable for ";
   PrintBasePath(WhichVFPtr.PathToBaseWithVFPtr, Out);
@@ -3042,7 +3082,8 @@ void VFTableBuilder::dumpLayout(raw_ostream &Out) {
       const CXXMethodDecl *MD = I->second;
 
       ThunkInfoVectorTy ThunksVector = Thunks[MD];
-      std::sort(ThunksVector.begin(), ThunksVector.end());
+      std::stable_sort(ThunksVector.begin(), ThunksVector.end(),
+                       MicrosoftThunkInfoStableSortComparator());
 
       Out << "Thunks for '" << MethodName << "' (" << ThunksVector.size();
       Out << (ThunksVector.size() == 1 ? " entry" : " entries") << ").\n";
@@ -3218,7 +3259,6 @@ void MicrosoftVFTableContext::computeVTableRelatedInformation(
     assert(VFTableLayouts.count(id) == 0);
     SmallVector<VTableLayout::VTableThunkTy, 1> VTableThunks(
         Builder.vtable_thunks_begin(), Builder.vtable_thunks_end());
-    std::sort(VTableThunks.begin(), VTableThunks.end());
     VFTableLayouts[id] = new VTableLayout(
         Builder.getNumVTableComponents(), Builder.vtable_component_begin(),
         VTableThunks.size(), VTableThunks.data(), EmptyAddressPointsMap, true);
diff --git a/clang/lib/CodeGen/CGCXXABI.h b/clang/lib/CodeGen/CGCXXABI.h
index 3a1c8d198dc..eaeb971dc42 100644
--- a/clang/lib/CodeGen/CGCXXABI.h
+++ b/clang/lib/CodeGen/CGCXXABI.h
@@ -339,11 +339,17 @@ public:
                                          SourceLocation CallLoc,
                                          llvm::Value *This) = 0;
 
+  virtual void adjustCallArgsForDestructorThunk(CodeGenFunction &CGF,
+                                                GlobalDecl GD,
+                                                CallArgList &CallArgs) {}
+
   /// Emit any tables needed to implement virtual inheritance.  For Itanium,
   /// this emits virtual table tables.  For the MSVC++ ABI, this emits virtual
   /// base tables.
   virtual void emitVirtualInheritanceTables(const CXXRecordDecl *RD) = 0;
 
+  virtual void setThunkLinkage(llvm::Function *Thunk, bool ForVTable) = 0;
+
   virtual void EmitReturnFromThunk(CodeGenFunction &CGF,
                                    RValue RV, QualType ResultType);
 
diff --git a/clang/lib/CodeGen/CGVTables.cpp b/clang/lib/CodeGen/CGVTables.cpp
index b987eb4d079..5ede5650b93 100644
--- a/clang/lib/CodeGen/CGVTables.cpp
+++ b/clang/lib/CodeGen/CGVTables.cpp
@@ -333,6 +333,9 @@ void CodeGenFunction::GenerateThunk(llvm::Function *Fn,
   // Add our adjusted 'this' pointer.
   CallArgs.add(RValue::get(AdjustedThisPtr), ThisType);
 
+  if (isa<CXXDestructorDecl>(MD))
+    CGM.getCXXABI().adjustCallArgsForDestructorThunk(*this, GD, CallArgs);
+
   // Add the rest of the parameters.
   for (FunctionDecl::param_const_iterator I = MD->param_begin(),
        E = MD->param_end(); I != E; ++I) {
@@ -390,14 +393,8 @@ void CodeGenFunction::GenerateThunk(llvm::Function *Fn,
   setThunkVisibility(CGM, MD, Thunk, Fn);
 }
 
-void CodeGenVTables::EmitThunk(GlobalDecl GD, const ThunkInfo &Thunk, 
-                               bool UseAvailableExternallyLinkage)
-{
-  if (CGM.getTarget().getCXXABI().isMicrosoft()) {
-    // Emission of thunks is not supported yet in Microsoft ABI.
-    return;
-  }
-
+void CodeGenVTables::emitThunk(GlobalDecl GD, const ThunkInfo &Thunk,
+                               bool ForVTable) {
   const CGFunctionInfo &FnInfo = CGM.getTypes().arrangeGlobalDeclaration(GD);
 
   // FIXME: re-use FnInfo in this computation.
@@ -435,9 +432,11 @@ void CodeGenVTables::EmitThunk(GlobalDecl GD, const ThunkInfo &Thunk,
   }
 
   llvm::Function *ThunkFn = cast<llvm::Function>(Entry);
+  bool ABIHasKeyFunctions = CGM.getTarget().getCXXABI().hasKeyFunctions();
+  bool UseAvailableExternallyLinkage = ForVTable && ABIHasKeyFunctions;
 
   if (!ThunkFn->isDeclaration()) {
-    if (UseAvailableExternallyLinkage) {
+    if (!ABIHasKeyFunctions || UseAvailableExternallyLinkage) {
       // There is already a thunk emitted for this function, do nothing.
       return;
     }
@@ -466,14 +465,17 @@ void CodeGenVTables::EmitThunk(GlobalDecl GD, const ThunkInfo &Thunk,
     CodeGenFunction(CGM).GenerateThunk(ThunkFn, FnInfo, GD, Thunk);
   }
 
-  if (UseAvailableExternallyLinkage)
-    ThunkFn->setLinkage(llvm::GlobalValue::AvailableExternallyLinkage);
+  CGM.getCXXABI().setThunkLinkage(ThunkFn, ForVTable);
 }
 
-void CodeGenVTables::MaybeEmitThunkAvailableExternally(GlobalDecl GD,
-                                                       const ThunkInfo &Thunk) {
-  // We only want to do this when building with optimizations.
-  if (!CGM.getCodeGenOpts().OptimizationLevel)
+void CodeGenVTables::maybeEmitThunkForVTable(GlobalDecl GD,
+                                             const ThunkInfo &Thunk) {
+  // If the ABI has key functions, only the TU with the key function should emit
+  // the thunk. However, we can allow inlining of thunks if we emit them with
+  // available_externally linkage together with vtables when optimizations are
+  // enabled.
+  if (CGM.getTarget().getCXXABI().hasKeyFunctions() &&
+      !CGM.getCodeGenOpts().OptimizationLevel)
     return;
 
   // We can't emit thunks for member functions with incomplete types.
@@ -482,7 +484,7 @@ void CodeGenVTables::MaybeEmitThunkAvailableExternally(GlobalDecl GD,
                                 cast<FunctionType>(MD->getType().getTypePtr())))
     return;
 
-  EmitThunk(GD, Thunk, /*UseAvailableExternallyLinkage=*/true);
+  emitThunk(GD, Thunk, /*ForVTable=*/true);
 }
 
 void CodeGenVTables::EmitThunks(GlobalDecl GD)
@@ -494,21 +496,18 @@ void CodeGenVTables::EmitThunks(GlobalDecl GD)
   if (isa<CXXDestructorDecl>(MD) && GD.getDtorType() == Dtor_Base)
     return;
 
+  const VTableContext::ThunkInfoVectorTy *ThunkInfoVector;
   if (VFTContext.isValid()) {
-    // FIXME: This is a temporary solution to force generation of vftables in
-    // Microsoft ABI. Remove when we thread VFTableContext through CodeGen.
-    VFTContext->getVFPtrOffsets(MD->getParent());
-    return;
+    ThunkInfoVector = VFTContext->getThunkInfo(GD);
+  } else {
+    ThunkInfoVector = VTContext.getThunkInfo(GD);
   }
 
-  const VTableContext::ThunkInfoVectorTy *ThunkInfoVector =
-    VTContext.getThunkInfo(MD);
   if (!ThunkInfoVector)
     return;
 
   for (unsigned I = 0, E = ThunkInfoVector->size(); I != E; ++I)
-    EmitThunk(GD, (*ThunkInfoVector)[I],
-              /*UseAvailableExternallyLinkage=*/false);
+    emitThunk(GD, (*ThunkInfoVector)[I], /*ForVTable=*/false);
 }
 
 llvm::Constant *
@@ -603,7 +602,7 @@ CodeGenVTables::CreateVTableInitializer(const CXXRecordDecl *RD,
             VTableThunks[NextVTableThunkIndex].first == I) {
           const ThunkInfo &Thunk = VTableThunks[NextVTableThunkIndex].second;
         
-          MaybeEmitThunkAvailableExternally(GD, Thunk);
+          maybeEmitThunkForVTable(GD, Thunk);
           Init = CGM.GetAddrOfThunk(GD, Thunk);
 
           NextVTableThunkIndex++;
diff --git a/clang/lib/CodeGen/CGVTables.h b/clang/lib/CodeGen/CGVTables.h
index 9b95952e5e8..e17ad89c5e7 100644
--- a/clang/lib/CodeGen/CGVTables.h
+++ b/clang/lib/CodeGen/CGVTables.h
@@ -52,15 +52,12 @@ class CodeGenVTables {
   /// indices.
   SecondaryVirtualPointerIndicesMapTy SecondaryVirtualPointerIndices;
 
-  /// EmitThunk - Emit a single thunk.
-  void EmitThunk(GlobalDecl GD, const ThunkInfo &Thunk, 
-                 bool UseAvailableExternallyLinkage);
-
-  /// MaybeEmitThunkAvailableExternally - Try to emit the given thunk with
-  /// available_externally linkage to allow for inlining of thunks.
-  /// This will be done iff optimizations are enabled and the member function
-  /// doesn't contain any incomplete types.
-  void MaybeEmitThunkAvailableExternally(GlobalDecl GD, const ThunkInfo &Thunk);
+  /// emitThunk - Emit a single thunk.
+  void emitThunk(GlobalDecl GD, const ThunkInfo &Thunk, bool ForVTable);
+
+  /// maybeEmitThunkForVTable - Emit the given thunk for the vtable if needed by
+  /// the ABI.
+  void maybeEmitThunkForVTable(GlobalDecl GD, const ThunkInfo &Thunk);
 
 public:
   /// CreateVTableInitializer - Create a vtable initializer for the given record
diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index ecf5d577981..1e34a16dd99 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -173,6 +173,13 @@ public:
 
   void emitVirtualInheritanceTables(const CXXRecordDecl *RD);
 
+  void setThunkLinkage(llvm::Function *Thunk, bool ForVTable) {
+    // Allow inlining of thunks by emitting them with available_externally
+    // linkage together with vtables when needed.
+    if (ForVTable)
+      Thunk->setLinkage(llvm::GlobalValue::AvailableExternallyLinkage);
+  }
+
   StringRef GetPureVirtualCallName() { return "__cxa_pure_virtual"; }
   StringRef GetDeletedVirtualCallName() { return "__cxa_deleted_virtual"; }
 
diff --git a/clang/lib/CodeGen/MicrosoftCXXABI.cpp b/clang/lib/CodeGen/MicrosoftCXXABI.cpp
index 1d73b213b7d..7452c860d0b 100644
--- a/clang/lib/CodeGen/MicrosoftCXXABI.cpp
+++ b/clang/lib/CodeGen/MicrosoftCXXABI.cpp
@@ -173,8 +173,20 @@ public:
                                  CXXDtorType DtorType, SourceLocation CallLoc,
                                  llvm::Value *This);
 
+  void adjustCallArgsForDestructorThunk(CodeGenFunction &CGF, GlobalDecl GD,
+                                        CallArgList &CallArgs) {
+    assert(GD.getDtorType() == Dtor_Deleting &&
+           "Only deleting destructor thunks are available in this ABI");
+    CallArgs.add(RValue::get(getStructorImplicitParamValue(CGF)),
+                             CGM.getContext().IntTy);
+  }
+
   void emitVirtualInheritanceTables(const CXXRecordDecl *RD);
 
+  void setThunkLinkage(llvm::Function *Thunk, bool ForVTable) {
+    Thunk->setLinkage(llvm::GlobalValue::WeakAnyLinkage);
+  }
+
   void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
                        llvm::GlobalVariable *DeclPtr,
                        bool PerformInit);