Continuing work on ObjC tidyup:

- Moved the CGObjCRuntime functions out of CGObjCMac.cpp into CGObjCRuntime.cpp

- Added generic functions in CGObjCRuntime for emitting @try and @synchronize
  blocks, usable by any runtime that uses DWARF exceptions.

- Made the GNU runtimes use these functions.

It should now be possible to replace the equivalent functions in
CGObjCNonFragileABIMac with simple calls to these two functions, providing the
runtime functions as arguments.  I'll post a diff to the list for review before
making any changes to the Mac runtime stuff.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@128274 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGObjCGNU.cpp b/lib/CodeGen/CGObjCGNU.cpp
index 864c73f..baf4ce4 100644
--- a/lib/CodeGen/CGObjCGNU.cpp
+++ b/lib/CodeGen/CGObjCGNU.cpp
@@ -74,6 +74,7 @@
        CGM =Mod;
        FunctionName = name;
        Function = 0;
+       ArgTys.clear();
        va_list Args;
        va_start(Args, RetTy);
          while (const llvm::Type *ArgTy = va_arg(Args, const llvm::Type*))
@@ -88,12 +89,15 @@
     */
    operator llvm::Function*() {
      if (!Function) {
-       assert(0 != CGM && "Using an uninitialized LazyRuntimeFunction!");
+       if (0 == FunctionName) return 0;
+       // We put the return type on the end of the vector, so pop it back off
        const llvm::Type *RetTy = ArgTys.back();
        ArgTys.pop_back();
        llvm::FunctionType *FTy = llvm::FunctionType::get(RetTy, ArgTys, false);
        Function =
          cast<llvm::Function>(CGM->CreateRuntimeFunction(FTy, FunctionName));
+       // We won't need to use the types again, so we may as well clean up the
+       // vector now
        ArgTys.resize(0);
      }
      return Function;
@@ -128,26 +132,64 @@
   const llvm::Type *BoolTy;
   /// Metadata kind used to tie method lookups to message sends.
   unsigned msgSendMDKind;
-  llvm::Constant *MakeConstantString(const std::string &Str, const std::string
+  llvm::Constant *MakeConstantString(const std::string &Str,
+                                     const std::string &Name="") {
+    llvm::Constant *ConstStr = CGM.GetAddrOfConstantCString(Str, Name.c_str());
+    return llvm::ConstantExpr::getGetElementPtr(ConstStr, Zeros, 2);
+  }
+  llvm::Constant *ExportUniqueString(const std::string &Str,
+                                     const std::string prefix) {
+    std::string name = prefix + Str;
+    llvm::Constant *ConstStr = TheModule.getGlobalVariable(name);
+    if (!ConstStr) {
+      llvm::Constant *value = llvm::ConstantArray::get(VMContext, Str, true);
+      ConstStr = new llvm::GlobalVariable(TheModule, value->getType(), true,
+              llvm::GlobalValue::LinkOnceODRLinkage, value, prefix + Str);
+    }
+    return llvm::ConstantExpr::getGetElementPtr(ConstStr, Zeros, 2);
+  }
 
-      &Name="");
-  llvm::Constant *ExportUniqueString(const std::string &Str, const std::string
-          prefix);
   llvm::GlobalVariable *MakeGlobal(const llvm::StructType *Ty,
-    std::vector<llvm::Constant*> &V, llvm::StringRef Name="",
-    llvm::GlobalValue::LinkageTypes linkage=llvm::GlobalValue::InternalLinkage);
+                                   std::vector<llvm::Constant*> &V,
+                                   llvm::StringRef Name="",
+                                   llvm::GlobalValue::LinkageTypes linkage
+                                         =llvm::GlobalValue::InternalLinkage) {
+    llvm::Constant *C = llvm::ConstantStruct::get(Ty, V);
+    return new llvm::GlobalVariable(TheModule, Ty, false,
+        linkage, C, Name);
+  }
+
   llvm::GlobalVariable *MakeGlobal(const llvm::ArrayType *Ty,
-    std::vector<llvm::Constant*> &V, llvm::StringRef Name="",
-    llvm::GlobalValue::LinkageTypes linkage=llvm::GlobalValue::InternalLinkage);
+                                   std::vector<llvm::Constant*> &V,
+                                   llvm::StringRef Name="",
+                                   llvm::GlobalValue::LinkageTypes linkage
+                                         =llvm::GlobalValue::InternalLinkage) {
+    llvm::Constant *C = llvm::ConstantArray::get(Ty, V);
+    return new llvm::GlobalVariable(TheModule, Ty, false,
+                                    linkage, C, Name);
+  }
   llvm::GlobalVariable *MakeGlobalArray(const llvm::Type *Ty,
-    std::vector<llvm::Constant*> &V, llvm::StringRef Name="",
-    llvm::GlobalValue::LinkageTypes linkage=llvm::GlobalValue::InternalLinkage);
+                                        std::vector<llvm::Constant*> &V,
+                                        llvm::StringRef Name="",
+                                        llvm::GlobalValue::LinkageTypes linkage
+                                         =llvm::GlobalValue::InternalLinkage) {
+    llvm::ArrayType *ArrayTy = llvm::ArrayType::get(Ty, V.size());
+    return MakeGlobal(ArrayTy, V, Name, linkage);
+  }
+  /**
+   * Ensures that the value has the required type, by inserting a bitcast if
+   * required.  This function lets us avoid inserting bitcasts that are
+   * redundant.
+   */
   llvm::Value* EnforceType(CGBuilderTy B, llvm::Value *V, const llvm::Type *Ty){
     if (V->getType() == Ty) return V;
     return B.CreateBitCast(V, Ty);
   }
   // Some zeros used for GEPs in lots of places.
   llvm::Constant *Zeros[2];
+  /**
+   * Null pointer value.  Mainly used as a terminator in various arrays.
+   */
   llvm::Constant *NULLPtr;
   llvm::LLVMContext &VMContext;
 private:
@@ -180,10 +222,16 @@
   LazyRuntimeFunction IvarAssignFn, StrongCastAssignFn, MemMoveFn, WeakReadFn, 
     WeakAssignFn, GlobalAssignFn;
 
+protected:
   LazyRuntimeFunction ExceptionThrowFn;
+  LazyRuntimeFunction ExceptionReThrowFn;
+  LazyRuntimeFunction EnterCatchFn;
+  LazyRuntimeFunction ExitCatchFn;
   LazyRuntimeFunction SyncEnterFn;
   LazyRuntimeFunction SyncExitFn;
 
+private:
+
   LazyRuntimeFunction EnumerationMutationFn;
   LazyRuntimeFunction GetPropertyFn;
   LazyRuntimeFunction SetPropertyFn;
@@ -237,7 +285,6 @@
   llvm::GlobalVariable *ObjCIvarOffsetVariable(const ObjCInterfaceDecl *ID,
       const ObjCIvarDecl *Ivar);
   void EmitClassRef(const std::string &className);
-  void EmitObjCXXTryStmt(CodeGenFunction &CGF, const ObjCAtTryStmt &S);
 protected:
   virtual llvm::Value *LookupIMP(CodeGenFunction &CGF,
                                  llvm::Value *&Receiver,
@@ -463,6 +510,16 @@
       // Slot_t objc_msg_lookup_super(struct objc_super*, SEL);
       SlotLookupSuperFn.init(&CGM, "objc_slot_lookup_super", SlotTy,
               PtrToObjCSuperTy, SelectorTy, NULL);
+      // If we're in ObjC++ mode, then we want to make 
+      if (CGM.getLangOptions().CPlusPlus) {
+        const llvm::Type *VoidTy = llvm::Type::getVoidTy(VMContext);
+        // void *__cxa_begin_catch(void *e)
+        EnterCatchFn.init(&CGM, "__cxa_begin_catch", PtrTy, PtrTy, NULL);
+        // void __cxa_end_catch(void)
+        EnterCatchFn.init(&CGM, "__cxa_end_catch", VoidTy, NULL);
+        // void _Unwind_Resume_or_Rethrow(void*)
+        EnterCatchFn.init(&CGM, "_Unwind_Resume_or_Rethrow", VoidTy, PtrTy, NULL);
+      }
     }
 };
 
@@ -551,6 +608,7 @@
 
   // void objc_exception_throw(id);
   ExceptionThrowFn.init(&CGM, "objc_exception_throw", VoidTy, IdTy, NULL);
+  ExceptionReThrowFn.init(&CGM, "objc_exception_throw", VoidTy, IdTy, NULL);
   // int objc_sync_enter(id);
   SyncEnterFn.init(&CGM, "objc_sync_enter", IntTy, IdTy, NULL);
   // int objc_sync_exit(id);
@@ -580,6 +638,7 @@
   IMPTy = llvm::PointerType::getUnqual(llvm::FunctionType::get(IdTy, IMPArgs,
               true));
 
+  // Don't bother initialising the GC stuff unless we're compiling in GC mode
   if (CGM.getLangOptions().getGCMode() != LangOptions::NonGC) {
     // Get selectors needed in GC mode
     RetainSel = GetNullarySelector("retain", CGM.getContext());
@@ -671,6 +730,29 @@
 }
 
 llvm::Constant *CGObjCGNU::GetEHType(QualType T) {
+  if (!CGM.getLangOptions().CPlusPlus) {
+      if (T->isObjCIdType()
+          || T->isObjCQualifiedIdType()) {
+        // With the old ABI, there was only one kind of catchall, which broke
+        // foreign exceptions.  With the new ABI, we use __objc_id_typeinfo as
+        // a pointer indicating object catchalls, and NULL to indicate real
+        // catchalls
+        if (CGM.getLangOptions().ObjCNonFragileABI) {
+          return MakeConstantString("@id");
+        } else {
+          return 0;
+        }
+      }
+
+      // All other types should be Objective-C interface pointer types.
+      const ObjCObjectPointerType *OPT =
+        T->getAs<ObjCObjectPointerType>();
+      assert(OPT && "Invalid @catch type.");
+      const ObjCInterfaceDecl *IDecl =
+        OPT->getObjectType()->getInterface();
+      assert(IDecl && "Invalid @catch type.");
+      return MakeConstantString(IDecl->getIdentifier()->getName());
+  }
   // For Objective-C++, we want to provide the ability to catch both C++ and
   // Objective-C objects in the same function.
 
@@ -729,44 +811,6 @@
   return llvm::ConstantExpr::getBitCast(TI, PtrToInt8Ty);
 }
 
-llvm::Constant *CGObjCGNU::MakeConstantString(const std::string &Str,
-                                              const std::string &Name) {
-  llvm::Constant *ConstStr = CGM.GetAddrOfConstantCString(Str, Name.c_str());
-  return llvm::ConstantExpr::getGetElementPtr(ConstStr, Zeros, 2);
-}
-llvm::Constant *CGObjCGNU::ExportUniqueString(const std::string &Str,
-        const std::string prefix) {
-  std::string name = prefix + Str;
-  llvm::Constant *ConstStr = TheModule.getGlobalVariable(name);
-  if (!ConstStr) {
-    llvm::Constant *value = llvm::ConstantArray::get(VMContext, Str, true);
-    ConstStr = new llvm::GlobalVariable(TheModule, value->getType(), true,
-            llvm::GlobalValue::LinkOnceODRLinkage, value, prefix + Str);
-  }
-  return llvm::ConstantExpr::getGetElementPtr(ConstStr, Zeros, 2);
-}
-
-llvm::GlobalVariable *CGObjCGNU::MakeGlobal(const llvm::StructType *Ty,
-    std::vector<llvm::Constant*> &V, llvm::StringRef Name,
-    llvm::GlobalValue::LinkageTypes linkage) {
-  llvm::Constant *C = llvm::ConstantStruct::get(Ty, V);
-  return new llvm::GlobalVariable(TheModule, Ty, false,
-      linkage, C, Name);
-}
-
-llvm::GlobalVariable *CGObjCGNU::MakeGlobal(const llvm::ArrayType *Ty,
-    std::vector<llvm::Constant*> &V, llvm::StringRef Name,
-    llvm::GlobalValue::LinkageTypes linkage) {
-  llvm::Constant *C = llvm::ConstantArray::get(Ty, V);
-  return new llvm::GlobalVariable(TheModule, Ty, false,
-                                  linkage, C, Name);
-}
-llvm::GlobalVariable *CGObjCGNU::MakeGlobalArray(const llvm::Type *Ty,
-  std::vector<llvm::Constant*> &V, llvm::StringRef Name,
-  llvm::GlobalValue::LinkageTypes linkage) {
-  llvm::ArrayType *ArrayTy = llvm::ArrayType::get(Ty, V.size());
-  return MakeGlobal(ArrayTy, V, Name, linkage);
-}
 /// Generate an NSConstantString object.
 llvm::Constant *CGObjCGNU::GenerateConstantString(const StringLiteral *SL) {
 
@@ -2073,180 +2117,11 @@
   return EnumerationMutationFn;
 }
 
-namespace {
-  struct CallSyncExit : EHScopeStack::Cleanup {
-    llvm::Value *SyncExitFn;
-    llvm::Value *SyncArg;
-    CallSyncExit(llvm::Value *SyncExitFn, llvm::Value *SyncArg)
-      : SyncExitFn(SyncExitFn), SyncArg(SyncArg) {}
-
-    void Emit(CodeGenFunction &CGF, bool IsForEHCleanup) {
-      CGF.Builder.CreateCall(SyncExitFn, SyncArg)->setDoesNotThrow();
-    }
-  };
-}
-
 void CGObjCGNU::EmitSynchronizedStmt(CodeGenFunction &CGF,
                                      const ObjCAtSynchronizedStmt &S) {
-  // Evaluate the lock operand.  This should dominate the cleanup.
-  llvm::Value *SyncArg =
-    CGF.EmitScalarExpr(S.getSynchExpr());
-
-  // Acquire the lock.
-  SyncArg = CGF.Builder.CreateBitCast(SyncArg, IdTy);
-  CGF.Builder.CreateCall(SyncEnterFn, SyncArg);
-
-  // Register an all-paths cleanup to release the lock.
-  CGF.EHStack.pushCleanup<CallSyncExit>(NormalAndEHCleanup, SyncExitFn,
-      SyncArg);
-
-  // Emit the body of the statement.
-  CGF.EmitStmt(S.getSynchBody());
-
-  // Pop the lock-release cleanup.
-  CGF.PopCleanupBlock();
+  EmitAtSynchronizedStmt(CGF, S, SyncEnterFn, SyncExitFn);
 }
 
-namespace {
-  struct CatchHandler {
-    const VarDecl *Variable;
-    const Stmt *Body;
-    llvm::BasicBlock *Block;
-    llvm::Value *TypeInfo;
-  };
-
-  struct CallObjCEndCatch : EHScopeStack::Cleanup {
-    CallObjCEndCatch(bool MightThrow, llvm::Value *Fn) :
-      MightThrow(MightThrow), Fn(Fn) {}
-    bool MightThrow;
-    llvm::Value *Fn;
-
-    void Emit(CodeGenFunction &CGF, bool IsForEH) {
-      if (!MightThrow) {
-        CGF.Builder.CreateCall(Fn)->setDoesNotThrow();
-        return;
-      }
-
-      CGF.EmitCallOrInvoke(Fn, 0, 0);
-    }
-  };
-}
-
-void CGObjCGNU::EmitObjCXXTryStmt(CodeGenFunction &CGF,
-                                  const ObjCAtTryStmt &S) {
-  std::vector<const llvm::Type*> Args(1, PtrToInt8Ty);
-  llvm::FunctionType *FTy = llvm::FunctionType::get(PtrToInt8Ty, Args, false);
-  const llvm::Type *VoidTy = llvm::Type::getVoidTy(VMContext);
-
-  llvm::Constant *beginCatchFn =
-    CGM.CreateRuntimeFunction(FTy, "__cxa_begin_catch");
-
-  FTy = llvm::FunctionType::get(VoidTy, false);
-  llvm::Constant *endCatchFn =
-    CGM.CreateRuntimeFunction(FTy, "__cxa_end_catch");
-  FTy = llvm::FunctionType::get(VoidTy, Args, false);
-  llvm::Constant *exceptionRethrowFn =
-    CGM.CreateRuntimeFunction(FTy, "_Unwind_Resume_or_Rethrow");
-
-  // Jump destination for falling out of catch bodies.
-  CodeGenFunction::JumpDest Cont;
-  if (S.getNumCatchStmts())
-    Cont = CGF.getJumpDestInCurrentScope("eh.cont");
-
-  CodeGenFunction::FinallyInfo FinallyInfo;
-  if (const ObjCAtFinallyStmt *Finally = S.getFinallyStmt())
-    FinallyInfo = CGF.EnterFinallyBlock(Finally->getFinallyBody(),
-                                        beginCatchFn,
-                                        endCatchFn,
-                                        exceptionRethrowFn);
-
-  llvm::SmallVector<CatchHandler, 8> Handlers;
-
-  // Enter the catch, if there is one.
-  if (S.getNumCatchStmts()) {
-    for (unsigned I = 0, N = S.getNumCatchStmts(); I != N; ++I) {
-      const ObjCAtCatchStmt *CatchStmt = S.getCatchStmt(I);
-      const VarDecl *CatchDecl = CatchStmt->getCatchParamDecl();
-
-      Handlers.push_back(CatchHandler());
-      CatchHandler &Handler = Handlers.back();
-      Handler.Variable = CatchDecl;
-      Handler.Body = CatchStmt->getCatchBody();
-      Handler.Block = CGF.createBasicBlock("catch");
-
-      // @catch(...) always matches.
-      if (!CatchDecl) {
-        Handler.TypeInfo = 0; // catch-all
-        // Don't consider any other catches.
-        break;
-      }
-
-      Handler.TypeInfo = GetEHType(CatchDecl->getType());
-    }
-
-    EHCatchScope *Catch = CGF.EHStack.pushCatch(Handlers.size());
-    for (unsigned I = 0, E = Handlers.size(); I != E; ++I)
-      Catch->setHandler(I, Handlers[I].TypeInfo, Handlers[I].Block);
-  }
-  
-  // Emit the try body.
-  CGF.EmitStmt(S.getTryBody());
-
-  // Leave the try.
-  if (S.getNumCatchStmts())
-    CGF.EHStack.popCatch();
-
-  // Remember where we were.
-  CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveAndClearIP();
-
-  // Emit the handlers.
-  for (unsigned I = 0, E = Handlers.size(); I != E; ++I) {
-    CatchHandler &Handler = Handlers[I];
-
-    CGF.EmitBlock(Handler.Block);
-    llvm::Value *RawExn = CGF.Builder.CreateLoad(CGF.getExceptionSlot());
-
-    // Enter the catch.
-    llvm::CallInst *Exn =
-      CGF.Builder.CreateCall(beginCatchFn, RawExn,
-                             "exn.adjusted");
-    Exn->setDoesNotThrow();
-
-    // Add a cleanup to leave the catch.
-    bool EndCatchMightThrow = (Handler.Variable == 0);
-    CGF.EHStack.pushCleanup<CallObjCEndCatch>(NormalAndEHCleanup,
-                                              EndCatchMightThrow,
-                                              endCatchFn);
-
-    // Bind the catch parameter if it exists.
-    if (const VarDecl *CatchParam = Handler.Variable) {
-      const llvm::Type *CatchType = CGF.ConvertType(CatchParam->getType());
-      llvm::Value *CastExn = CGF.Builder.CreateBitCast(Exn, CatchType);
-
-      CGF.EmitAutoVarDecl(*CatchParam);
-      CGF.Builder.CreateStore(CastExn, CGF.GetAddrOfLocalVar(CatchParam));
-    }
-
-    CGF.ObjCEHValueStack.push_back(Exn);
-    CGF.EmitStmt(Handler.Body);
-    CGF.ObjCEHValueStack.pop_back();
-
-    // Leave the earlier cleanup.
-    CGF.PopCleanupBlock();
-
-    CGF.EmitBranchThroughCleanup(Cont);
-  }  
-
-  // Go back to the try-statement fallthrough.
-  CGF.Builder.restoreIP(SavedIP);
-
-  // Pop out of the normal cleanup on the finally.
-  if (S.getFinallyStmt())
-    CGF.ExitFinallyBlock(FinallyInfo);
-
-  if (Cont.isValid())
-    CGF.EmitBlock(Cont.getBlock());
-}
 
 void CGObjCGNU::EmitTryStmt(CodeGenFunction &CGF,
                             const ObjCAtTryStmt &S) {
@@ -2258,127 +2133,11 @@
   // catch handlers with calls to __blah_begin_catch/__blah_end_catch
   // (or even _Unwind_DeleteException), but probably doesn't
   // interoperate very well with foreign exceptions.
-
+  //
   // In Objective-C++ mode, we actually emit something equivalent to the C++
-  // exception handler.
-  if (CGM.getLangOptions().CPlusPlus) {
-    EmitObjCXXTryStmt(CGF, S);
-    return;
-  }
-
-  // Jump destination for falling out of catch bodies.
-  CodeGenFunction::JumpDest Cont;
-  if (S.getNumCatchStmts())
-    Cont = CGF.getJumpDestInCurrentScope("eh.cont");
-
-  // We handle @finally statements by pushing them as a cleanup
-  // before entering the catch.
-  CodeGenFunction::FinallyInfo FinallyInfo;
-  if (const ObjCAtFinallyStmt *Finally = S.getFinallyStmt()) {
-    FinallyInfo = CGF.EnterFinallyBlock(Finally->getFinallyBody(), 0, 0,
-                                        ExceptionThrowFn);
-  }
-
-  llvm::SmallVector<CatchHandler, 8> Handlers;
-
-  // Enter the catch, if there is one.
-  if (S.getNumCatchStmts()) {
-    for (unsigned I = 0, N = S.getNumCatchStmts(); I != N; ++I) {
-      const ObjCAtCatchStmt *CatchStmt = S.getCatchStmt(I);
-      const VarDecl *CatchDecl = CatchStmt->getCatchParamDecl();
-
-      Handlers.push_back(CatchHandler());
-      CatchHandler &Handler = Handlers.back();
-      Handler.Variable = CatchDecl;
-      Handler.Body = CatchStmt->getCatchBody();
-      Handler.Block = CGF.createBasicBlock("catch");
-
-      // @catch() and @catch(id) both catch any ObjC exception.
-      // Treat them as catch-alls.
-      // really be catching foreign exceptions?
-      
-      if (!CatchDecl) {
-        Handler.TypeInfo = 0; // catch-all
-        // Don't consider any other catches.
-        break;
-      }
-      if (CatchDecl->getType()->isObjCIdType()
-          || CatchDecl->getType()->isObjCQualifiedIdType()) {
-        // With the old ABI, there was only one kind of catchall, which broke
-        // foreign exceptions.  With the new ABI, we use __objc_id_typeinfo as
-        // a pointer indicating object catchalls, and NULL to indicate real
-        // catchalls
-        if (CGM.getLangOptions().ObjCNonFragileABI) {
-          Handler.TypeInfo = MakeConstantString("@id");
-          continue;
-        } else {
-          Handler.TypeInfo = 0; // catch-all
-          // Don't consider any other catches.
-          break;
-        }
-      }
-
-      // All other types should be Objective-C interface pointer types.
-      const ObjCObjectPointerType *OPT =
-        CatchDecl->getType()->getAs<ObjCObjectPointerType>();
-      assert(OPT && "Invalid @catch type.");
-      const ObjCInterfaceDecl *IDecl =
-        OPT->getObjectType()->getInterface();
-      assert(IDecl && "Invalid @catch type.");
-      Handler.TypeInfo = MakeConstantString(IDecl->getNameAsString());
-    }
-
-    EHCatchScope *Catch = CGF.EHStack.pushCatch(Handlers.size());
-    for (unsigned I = 0, E = Handlers.size(); I != E; ++I)
-      Catch->setHandler(I, Handlers[I].TypeInfo, Handlers[I].Block);
-  }
-  
-  // Emit the try body.
-  CGF.EmitStmt(S.getTryBody());
-
-  // Leave the try.
-  if (S.getNumCatchStmts())
-    CGF.EHStack.popCatch();
-
-  // Remember where we were.
-  CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveAndClearIP();
-
-  // Emit the handlers.
-  for (unsigned I = 0, E = Handlers.size(); I != E; ++I) {
-    CatchHandler &Handler = Handlers[I];
-    CGF.EmitBlock(Handler.Block);
-
-    llvm::Value *Exn = CGF.Builder.CreateLoad(CGF.getExceptionSlot());
-
-    // Bind the catch parameter if it exists.
-    if (const VarDecl *CatchParam = Handler.Variable) {
-      const llvm::Type *CatchType = CGF.ConvertType(CatchParam->getType());
-      Exn = CGF.Builder.CreateBitCast(Exn, CatchType);
-
-      CGF.EmitAutoVarDecl(*CatchParam);
-      CGF.Builder.CreateStore(Exn, CGF.GetAddrOfLocalVar(CatchParam));
-    }
-
-    CGF.ObjCEHValueStack.push_back(Exn);
-    CGF.EmitStmt(Handler.Body);
-    CGF.ObjCEHValueStack.pop_back();
-
-    CGF.EmitBranchThroughCleanup(Cont);
-  }  
-
-  // Go back to the try-statement fallthrough.
-  CGF.Builder.restoreIP(SavedIP);
-
-  // Pop out of the finally.
-  if (S.getFinallyStmt())
-    CGF.ExitFinallyBlock(FinallyInfo);
-
-  if (Cont.isValid()) {
-    if (Cont.getBlock()->use_empty())
-      delete Cont.getBlock();
-    else
-      CGF.EmitBlock(Cont.getBlock());
-  }
+  // exception handler. 
+  EmitTryCatchStmt(CGF, S, EnterCatchFn, ExitCatchFn, ExceptionReThrowFn);
+  return ;
 }
 
 void CGObjCGNU::EmitThrowStmt(CodeGenFunction &CGF,