1 //===--- CGException.cpp - Emit LLVM Code for C++ exceptions --------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This contains code dealing with C++ exception related code generation.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "clang/AST/StmtCXX.h"
15 
16 #include "llvm/Intrinsics.h"
17 
18 #include "CodeGenFunction.h"
19 using namespace clang;
20 using namespace CodeGen;
21 
22 static llvm::Constant *getAllocateExceptionFn(CodeGenFunction &CGF) {
23   // void *__cxa_allocate_exception(size_t thrown_size);
24   const llvm::Type *SizeTy = CGF.ConvertType(CGF.getContext().getSizeType());
25   std::vector<const llvm::Type*> Args(1, SizeTy);
26 
27   const llvm::FunctionType *FTy =
28   llvm::FunctionType::get(llvm::Type::getInt8PtrTy(CGF.getLLVMContext()),
29                           Args, false);
30 
31   return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_allocate_exception");
32 }
33 
34 static llvm::Constant *getFreeExceptionFn(CodeGenFunction &CGF) {
35   // void __cxa_free_exception(void *thrown_exception);
36   const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGF.getLLVMContext());
37   std::vector<const llvm::Type*> Args(1, Int8PtrTy);
38 
39   const llvm::FunctionType *FTy =
40   llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()),
41                           Args, false);
42 
43   return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_free_exception");
44 }
45 
46 static llvm::Constant *getThrowFn(CodeGenFunction &CGF) {
47   // void __cxa_throw(void *thrown_exception, std::type_info *tinfo,
48   //                  void (*dest) (void *));
49 
50   const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGF.getLLVMContext());
51   std::vector<const llvm::Type*> Args(3, Int8PtrTy);
52 
53   const llvm::FunctionType *FTy =
54     llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()),
55                             Args, false);
56 
57   return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_throw");
58 }
59 
60 static llvm::Constant *getReThrowFn(CodeGenFunction &CGF) {
61   // void __cxa_rethrow();
62 
63   const llvm::FunctionType *FTy =
64     llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()), false);
65 
66   return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_rethrow");
67 }
68 
69 static llvm::Constant *getBeginCatchFn(CodeGenFunction &CGF) {
70   // void* __cxa_begin_catch();
71 
72   const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGF.getLLVMContext());
73   std::vector<const llvm::Type*> Args(1, Int8PtrTy);
74 
75   const llvm::FunctionType *FTy =
76     llvm::FunctionType::get(Int8PtrTy, Args, false);
77 
78   return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_begin_catch");
79 }
80 
81 static llvm::Constant *getEndCatchFn(CodeGenFunction &CGF) {
82   // void __cxa_end_catch();
83 
84   const llvm::FunctionType *FTy =
85     llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()), false);
86 
87   return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_end_catch");
88 }
89 
90 static llvm::Constant *getUnexpectedFn(CodeGenFunction &CGF) {
91   // void __cxa_call_unexepcted(void *thrown_exception);
92 
93   const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGF.getLLVMContext());
94   std::vector<const llvm::Type*> Args(1, Int8PtrTy);
95 
96   const llvm::FunctionType *FTy =
97     llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()),
98                             Args, false);
99 
100   return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_call_unexpected");
101 }
102 
103 static llvm::Constant *getUnwindResumeOrRethrowFn(CodeGenFunction &CGF) {
104   const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGF.getLLVMContext());
105   std::vector<const llvm::Type*> Args(1, Int8PtrTy);
106 
107   const llvm::FunctionType *FTy =
108     llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()), Args,
109                             false);
110 
111   if (CGF.CGM.getLangOptions().SjLjExceptions)
112     return CGF.CGM.CreateRuntimeFunction(FTy, "_Unwind_SjLj_Resume");
113   return CGF.CGM.CreateRuntimeFunction(FTy, "_Unwind_Resume_or_Rethrow");
114 }
115 
116 static llvm::Constant *getTerminateFn(CodeGenFunction &CGF) {
117   // void __terminate();
118 
119   const llvm::FunctionType *FTy =
120     llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()), false);
121 
122   return CGF.CGM.CreateRuntimeFunction(FTy, "_ZSt9terminatev");
123 }
124 
125 // CopyObject - Utility to copy an object.  Calls copy constructor as necessary.
126 // DestPtr is casted to the right type.
127 static void CopyObject(CodeGenFunction &CGF, const Expr *E,
128                        llvm::Value *DestPtr, llvm::Value *ExceptionPtrPtr) {
129   QualType ObjectType = E->getType();
130 
131   // Store the throw exception in the exception object.
132   if (!CGF.hasAggregateLLVMType(ObjectType)) {
133     llvm::Value *Value = CGF.EmitScalarExpr(E);
134     const llvm::Type *ValuePtrTy = Value->getType()->getPointerTo();
135 
136     CGF.Builder.CreateStore(Value,
137                             CGF.Builder.CreateBitCast(DestPtr, ValuePtrTy));
138   } else {
139     const llvm::Type *Ty = CGF.ConvertType(ObjectType)->getPointerTo();
140     const CXXRecordDecl *RD =
141       cast<CXXRecordDecl>(ObjectType->getAs<RecordType>()->getDecl());
142 
143     llvm::Value *This = CGF.Builder.CreateBitCast(DestPtr, Ty);
144     if (RD->hasTrivialCopyConstructor()) {
145       CGF.EmitAggExpr(E, This, false);
146     } else if (CXXConstructorDecl *CopyCtor
147                = RD->getCopyConstructor(CGF.getContext(), 0)) {
148       llvm::Value *CondPtr = 0;
149       if (CGF.Exceptions) {
150         CodeGenFunction::EHCleanupBlock Cleanup(CGF);
151         llvm::Constant *FreeExceptionFn = getFreeExceptionFn(CGF);
152 
153         llvm::BasicBlock *CondBlock = CGF.createBasicBlock("cond.free");
154         llvm::BasicBlock *Cont = CGF.createBasicBlock("cont");
155         CondPtr = CGF.CreateTempAlloca(llvm::Type::getInt1Ty(CGF.getLLVMContext()),
156                                        "doEHfree");
157 
158         CGF.Builder.CreateCondBr(CGF.Builder.CreateLoad(CondPtr),
159                                  CondBlock, Cont);
160         CGF.EmitBlock(CondBlock);
161 
162         // Load the exception pointer.
163         llvm::Value *ExceptionPtr = CGF.Builder.CreateLoad(ExceptionPtrPtr);
164         CGF.Builder.CreateCall(FreeExceptionFn, ExceptionPtr);
165 
166         CGF.EmitBlock(Cont);
167       }
168 
169       if (CondPtr)
170         CGF.Builder.CreateStore(llvm::ConstantInt::getTrue(CGF.getLLVMContext()),
171                                 CondPtr);
172 
173       llvm::Value *Src = CGF.EmitLValue(E).getAddress();
174 
175       if (CondPtr)
176         CGF.Builder.CreateStore(llvm::ConstantInt::getFalse(CGF.getLLVMContext()),
177                                 CondPtr);
178 
179       llvm::BasicBlock *TerminateHandler = CGF.getTerminateHandler();
180       llvm::BasicBlock *PrevLandingPad = CGF.getInvokeDest();
181       CGF.setInvokeDest(TerminateHandler);
182 
183       // Stolen from EmitClassAggrMemberwiseCopy
184       llvm::Value *Callee = CGF.CGM.GetAddrOfCXXConstructor(CopyCtor,
185                                                             Ctor_Complete);
186       CallArgList CallArgs;
187       CallArgs.push_back(std::make_pair(RValue::get(This),
188                                       CopyCtor->getThisType(CGF.getContext())));
189 
190       // Push the Src ptr.
191       CallArgs.push_back(std::make_pair(RValue::get(Src),
192                                         CopyCtor->getParamDecl(0)->getType()));
193       const FunctionProtoType *FPT
194         = CopyCtor->getType()->getAs<FunctionProtoType>();
195       CGF.EmitCall(CGF.CGM.getTypes().getFunctionInfo(CallArgs, FPT),
196                    Callee, ReturnValueSlot(), CallArgs, CopyCtor);
197       CGF.setInvokeDest(PrevLandingPad);
198     } else
199       llvm_unreachable("uncopyable object");
200   }
201 }
202 
203 // CopyObject - Utility to copy an object.  Calls copy constructor as necessary.
204 // N is casted to the right type.
205 static void CopyObject(CodeGenFunction &CGF, QualType ObjectType,
206                        bool WasPointer, bool WasPointerReference,
207                        llvm::Value *E, llvm::Value *N) {
208   // Store the throw exception in the exception object.
209   if (WasPointer || !CGF.hasAggregateLLVMType(ObjectType)) {
210     llvm::Value *Value = E;
211     if (!WasPointer)
212       Value = CGF.Builder.CreateLoad(Value);
213     const llvm::Type *ValuePtrTy = Value->getType()->getPointerTo(0);
214     if (WasPointerReference) {
215       llvm::Value *Tmp = CGF.CreateTempAlloca(Value->getType(), "catch.param");
216       CGF.Builder.CreateStore(Value, Tmp);
217       Value = Tmp;
218       ValuePtrTy = Value->getType()->getPointerTo(0);
219     }
220     N = CGF.Builder.CreateBitCast(N, ValuePtrTy);
221     CGF.Builder.CreateStore(Value, N);
222   } else {
223     const llvm::Type *Ty = CGF.ConvertType(ObjectType)->getPointerTo(0);
224     const CXXRecordDecl *RD;
225     RD = cast<CXXRecordDecl>(ObjectType->getAs<RecordType>()->getDecl());
226     llvm::Value *This = CGF.Builder.CreateBitCast(N, Ty);
227     if (RD->hasTrivialCopyConstructor()) {
228       CGF.EmitAggregateCopy(This, E, ObjectType);
229     } else if (CXXConstructorDecl *CopyCtor
230                = RD->getCopyConstructor(CGF.getContext(), 0)) {
231       llvm::Value *Src = E;
232 
233       // Stolen from EmitClassAggrMemberwiseCopy
234       llvm::Value *Callee = CGF.CGM.GetAddrOfCXXConstructor(CopyCtor,
235                                                             Ctor_Complete);
236       CallArgList CallArgs;
237       CallArgs.push_back(std::make_pair(RValue::get(This),
238                                       CopyCtor->getThisType(CGF.getContext())));
239 
240       // Push the Src ptr.
241       CallArgs.push_back(std::make_pair(RValue::get(Src),
242                                         CopyCtor->getParamDecl(0)->getType()));
243 
244       const FunctionProtoType *FPT
245         = CopyCtor->getType()->getAs<FunctionProtoType>();
246       CGF.EmitCall(CGF.CGM.getTypes().getFunctionInfo(CallArgs, FPT),
247                    Callee, ReturnValueSlot(), CallArgs, CopyCtor);
248     } else
249       llvm_unreachable("uncopyable object");
250   }
251 }
252 
253 void CodeGenFunction::EmitCXXThrowExpr(const CXXThrowExpr *E) {
254   if (!E->getSubExpr()) {
255     if (getInvokeDest()) {
256       llvm::BasicBlock *Cont = createBasicBlock("invoke.cont");
257       Builder.CreateInvoke(getReThrowFn(*this), Cont, getInvokeDest())
258         ->setDoesNotReturn();
259       EmitBlock(Cont);
260     } else
261       Builder.CreateCall(getReThrowFn(*this))->setDoesNotReturn();
262     Builder.CreateUnreachable();
263 
264     // Clear the insertion point to indicate we are in unreachable code.
265     Builder.ClearInsertionPoint();
266     return;
267   }
268 
269   QualType ThrowType = E->getSubExpr()->getType();
270 
271   // Now allocate the exception object.
272   const llvm::Type *SizeTy = ConvertType(getContext().getSizeType());
273   uint64_t TypeSize = getContext().getTypeSize(ThrowType) / 8;
274 
275   llvm::Constant *AllocExceptionFn = getAllocateExceptionFn(*this);
276   llvm::Value *ExceptionPtr =
277     Builder.CreateCall(AllocExceptionFn,
278                        llvm::ConstantInt::get(SizeTy, TypeSize),
279                        "exception");
280 
281   llvm::Value *ExceptionPtrPtr =
282     CreateTempAlloca(ExceptionPtr->getType(), "exception.ptr");
283   Builder.CreateStore(ExceptionPtr, ExceptionPtrPtr);
284 
285 
286   CopyObject(*this, E->getSubExpr(), ExceptionPtr, ExceptionPtrPtr);
287 
288   // Now throw the exception.
289   const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(getLLVMContext());
290   llvm::Constant *TypeInfo = CGM.GetAddrOfRTTIDescriptor(ThrowType);
291   llvm::Constant *Dtor = llvm::Constant::getNullValue(Int8PtrTy);
292 
293   if (getInvokeDest()) {
294     llvm::BasicBlock *Cont = createBasicBlock("invoke.cont");
295     llvm::InvokeInst *ThrowCall =
296       Builder.CreateInvoke3(getThrowFn(*this), Cont, getInvokeDest(),
297                             ExceptionPtr, TypeInfo, Dtor);
298     ThrowCall->setDoesNotReturn();
299     EmitBlock(Cont);
300   } else {
301     llvm::CallInst *ThrowCall =
302       Builder.CreateCall3(getThrowFn(*this), ExceptionPtr, TypeInfo, Dtor);
303     ThrowCall->setDoesNotReturn();
304   }
305   Builder.CreateUnreachable();
306 
307   // Clear the insertion point to indicate we are in unreachable code.
308   Builder.ClearInsertionPoint();
309 
310   // FIXME: For now, emit a dummy basic block because expr emitters in generally
311   // are not ready to handle emitting expressions at unreachable points.
312   EnsureInsertPoint();
313 }
314 
315 void CodeGenFunction::EmitStartEHSpec(const Decl *D) {
316   if (!Exceptions)
317     return;
318 
319   const FunctionDecl* FD = dyn_cast_or_null<FunctionDecl>(D);
320   if (FD == 0)
321     return;
322   const FunctionProtoType *Proto = FD->getType()->getAs<FunctionProtoType>();
323   if (Proto == 0)
324     return;
325 
326   assert(!Proto->hasAnyExceptionSpec() && "function with parameter pack");
327 
328   if (!Proto->hasExceptionSpec())
329     return;
330 
331   llvm::Constant *Personality =
332     CGM.CreateRuntimeFunction(llvm::FunctionType::get(llvm::Type::getInt32Ty
333                                                       (VMContext),
334                                                       true),
335                               "__gxx_personality_v0");
336   Personality = llvm::ConstantExpr::getBitCast(Personality, PtrToInt8Ty);
337   llvm::Value *llvm_eh_exception =
338     CGM.getIntrinsic(llvm::Intrinsic::eh_exception);
339   llvm::Value *llvm_eh_selector =
340     CGM.getIntrinsic(llvm::Intrinsic::eh_selector);
341   const llvm::IntegerType *Int8Ty;
342   const llvm::PointerType *PtrToInt8Ty;
343   Int8Ty = llvm::Type::getInt8Ty(VMContext);
344   // C string type.  Used in lots of places.
345   PtrToInt8Ty = llvm::PointerType::getUnqual(Int8Ty);
346   llvm::Constant *Null = llvm::ConstantPointerNull::get(PtrToInt8Ty);
347   llvm::SmallVector<llvm::Value*, 8> SelectorArgs;
348 
349   llvm::BasicBlock *PrevLandingPad = getInvokeDest();
350   llvm::BasicBlock *EHSpecHandler = createBasicBlock("ehspec.handler");
351   llvm::BasicBlock *Match = createBasicBlock("match");
352   llvm::BasicBlock *Unwind = 0;
353 
354   assert(PrevLandingPad == 0 && "EHSpec has invoke context");
355   (void)PrevLandingPad;
356 
357   llvm::BasicBlock *Cont = createBasicBlock("cont");
358 
359   EmitBranchThroughCleanup(Cont);
360 
361   // Emit the statements in the try {} block
362   setInvokeDest(EHSpecHandler);
363 
364   EmitBlock(EHSpecHandler);
365   // Exception object
366   llvm::Value *Exc = Builder.CreateCall(llvm_eh_exception, "exc");
367   llvm::Value *RethrowPtr = CreateTempAlloca(Exc->getType(), "_rethrow");
368 
369   SelectorArgs.push_back(Exc);
370   SelectorArgs.push_back(Personality);
371   SelectorArgs.push_back(llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext),
372                                                 Proto->getNumExceptions()+1));
373 
374   for (unsigned i = 0; i < Proto->getNumExceptions(); ++i) {
375     QualType Ty = Proto->getExceptionType(i);
376     QualType ExceptType
377       = Ty.getNonReferenceType().getUnqualifiedType();
378     llvm::Value *EHType = CGM.GetAddrOfRTTIDescriptor(ExceptType);
379     SelectorArgs.push_back(EHType);
380   }
381   if (Proto->getNumExceptions())
382     SelectorArgs.push_back(Null);
383 
384   // Find which handler was matched.
385   llvm::Value *Selector
386     = Builder.CreateCall(llvm_eh_selector, SelectorArgs.begin(),
387                          SelectorArgs.end(), "selector");
388   if (Proto->getNumExceptions()) {
389     Unwind = createBasicBlock("Unwind");
390 
391     Builder.CreateStore(Exc, RethrowPtr);
392     Builder.CreateCondBr(Builder.CreateICmpSLT(Selector,
393                                                llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext),
394                                                                       0)),
395                          Match, Unwind);
396 
397     EmitBlock(Match);
398   }
399   Builder.CreateCall(getUnexpectedFn(*this), Exc)->setDoesNotReturn();
400   Builder.CreateUnreachable();
401 
402   if (Proto->getNumExceptions()) {
403     EmitBlock(Unwind);
404     Builder.CreateCall(getUnwindResumeOrRethrowFn(*this),
405                        Builder.CreateLoad(RethrowPtr));
406     Builder.CreateUnreachable();
407   }
408 
409   EmitBlock(Cont);
410 }
411 
412 void CodeGenFunction::EmitEndEHSpec(const Decl *D) {
413   if (!Exceptions)
414     return;
415 
416   const FunctionDecl* FD = dyn_cast_or_null<FunctionDecl>(D);
417   if (FD == 0)
418     return;
419   const FunctionProtoType *Proto = FD->getType()->getAs<FunctionProtoType>();
420   if (Proto == 0)
421     return;
422 
423   if (!Proto->hasExceptionSpec())
424     return;
425 
426   setInvokeDest(0);
427 }
428 
429 void CodeGenFunction::EmitCXXTryStmt(const CXXTryStmt &S) {
430   CXXTryStmtInfo Info = EnterCXXTryStmt(S);
431   EmitStmt(S.getTryBlock());
432   ExitCXXTryStmt(S, Info);
433 }
434 
435 CodeGenFunction::CXXTryStmtInfo
436 CodeGenFunction::EnterCXXTryStmt(const CXXTryStmt &S) {
437   CXXTryStmtInfo Info;
438   Info.SavedLandingPad = getInvokeDest();
439   Info.HandlerBlock = createBasicBlock("try.handler");
440   Info.FinallyBlock = createBasicBlock("finally");
441 
442   PushCleanupBlock(Info.FinallyBlock);
443   setInvokeDest(Info.HandlerBlock);
444 
445   return Info;
446 }
447 
448 void CodeGenFunction::ExitCXXTryStmt(const CXXTryStmt &S,
449                                      CXXTryStmtInfo TryInfo) {
450   // Pointer to the personality function
451   llvm::Constant *Personality =
452     CGM.CreateRuntimeFunction(llvm::FunctionType::get(llvm::Type::getInt32Ty
453                                                       (VMContext),
454                                                       true),
455                               "__gxx_personality_v0");
456   Personality = llvm::ConstantExpr::getBitCast(Personality, PtrToInt8Ty);
457   llvm::Value *llvm_eh_exception =
458     CGM.getIntrinsic(llvm::Intrinsic::eh_exception);
459   llvm::Value *llvm_eh_selector =
460     CGM.getIntrinsic(llvm::Intrinsic::eh_selector);
461 
462   llvm::BasicBlock *PrevLandingPad = TryInfo.SavedLandingPad;
463   llvm::BasicBlock *TryHandler = TryInfo.HandlerBlock;
464   llvm::BasicBlock *FinallyBlock = TryInfo.FinallyBlock;
465   llvm::BasicBlock *FinallyRethrow = createBasicBlock("finally.throw");
466   llvm::BasicBlock *FinallyEnd = createBasicBlock("finally.end");
467 
468   // Jump to end if there is no exception
469   EmitBranchThroughCleanup(FinallyEnd);
470 
471   llvm::BasicBlock *TerminateHandler = getTerminateHandler();
472 
473   // Emit the handlers
474   EmitBlock(TryHandler);
475 
476   const llvm::IntegerType *Int8Ty;
477   const llvm::PointerType *PtrToInt8Ty;
478   Int8Ty = llvm::Type::getInt8Ty(VMContext);
479   // C string type.  Used in lots of places.
480   PtrToInt8Ty = llvm::PointerType::getUnqual(Int8Ty);
481   llvm::Constant *Null = llvm::ConstantPointerNull::get(PtrToInt8Ty);
482   llvm::SmallVector<llvm::Value*, 8> SelectorArgs;
483   llvm::Value *llvm_eh_typeid_for =
484     CGM.getIntrinsic(llvm::Intrinsic::eh_typeid_for);
485   // Exception object
486   llvm::Value *Exc = Builder.CreateCall(llvm_eh_exception, "exc");
487   llvm::Value *RethrowPtr = CreateTempAlloca(Exc->getType(), "_rethrow");
488 
489   llvm::SmallVector<llvm::Value*, 8> Args;
490   Args.clear();
491   SelectorArgs.push_back(Exc);
492   SelectorArgs.push_back(Personality);
493 
494   bool HasCatchAll = false;
495   for (unsigned i = 0; i<S.getNumHandlers(); ++i) {
496     const CXXCatchStmt *C = S.getHandler(i);
497     VarDecl *CatchParam = C->getExceptionDecl();
498     if (CatchParam) {
499       // C++ [except.handle]p3 indicates that top-level cv-qualifiers
500       // are ignored.
501       QualType CaughtType = C->getCaughtType().getNonReferenceType();
502       llvm::Value *EHTypeInfo
503         = CGM.GetAddrOfRTTIDescriptor(CaughtType.getUnqualifiedType());
504       SelectorArgs.push_back(EHTypeInfo);
505     } else {
506       // null indicates catch all
507       SelectorArgs.push_back(Null);
508       HasCatchAll = true;
509     }
510   }
511 
512   // We use a cleanup unless there was already a catch all.
513   if (!HasCatchAll) {
514     SelectorArgs.push_back(Null);
515   }
516 
517   // Find which handler was matched.
518   llvm::Value *Selector
519     = Builder.CreateCall(llvm_eh_selector, SelectorArgs.begin(),
520                          SelectorArgs.end(), "selector");
521   for (unsigned i = 0; i<S.getNumHandlers(); ++i) {
522     const CXXCatchStmt *C = S.getHandler(i);
523     VarDecl *CatchParam = C->getExceptionDecl();
524     Stmt *CatchBody = C->getHandlerBlock();
525 
526     llvm::BasicBlock *Next = 0;
527 
528     if (SelectorArgs[i+2] != Null) {
529       llvm::BasicBlock *Match = createBasicBlock("match");
530       Next = createBasicBlock("catch.next");
531       const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(getLLVMContext());
532       llvm::Value *Id
533         = Builder.CreateCall(llvm_eh_typeid_for,
534                              Builder.CreateBitCast(SelectorArgs[i+2],
535                                                    Int8PtrTy));
536       Builder.CreateCondBr(Builder.CreateICmpEQ(Selector, Id),
537                            Match, Next);
538       EmitBlock(Match);
539     }
540 
541     llvm::BasicBlock *MatchEnd = createBasicBlock("match.end");
542     llvm::BasicBlock *MatchHandler = createBasicBlock("match.handler");
543 
544     PushCleanupBlock(MatchEnd);
545     setInvokeDest(MatchHandler);
546 
547     llvm::Value *ExcObject = Builder.CreateCall(getBeginCatchFn(*this), Exc);
548 
549     {
550       CleanupScope CatchScope(*this);
551       // Bind the catch parameter if it exists.
552       if (CatchParam) {
553         QualType CatchType = CatchParam->getType().getNonReferenceType();
554         setInvokeDest(TerminateHandler);
555         bool WasPointer = true;
556         bool WasPointerReference = false;
557         CatchType = CGM.getContext().getCanonicalType(CatchType);
558         if (CatchType.getTypePtr()->isPointerType()) {
559           if (isa<ReferenceType>(CatchParam->getType()))
560             WasPointerReference = true;
561         } else {
562           if (!isa<ReferenceType>(CatchParam->getType()))
563             WasPointer = false;
564           CatchType = getContext().getPointerType(CatchType);
565         }
566         ExcObject = Builder.CreateBitCast(ExcObject, ConvertType(CatchType));
567         EmitLocalBlockVarDecl(*CatchParam);
568         // FIXME: we need to do this sooner so that the EH region for the
569         // cleanup doesn't start until after the ctor completes, use a decl
570         // init?
571         CopyObject(*this, CatchParam->getType().getNonReferenceType(),
572                    WasPointer, WasPointerReference, ExcObject,
573                    GetAddrOfLocalVar(CatchParam));
574         setInvokeDest(MatchHandler);
575       }
576 
577       EmitStmt(CatchBody);
578     }
579 
580     EmitBranchThroughCleanup(FinallyEnd);
581 
582     EmitBlock(MatchHandler);
583 
584     llvm::Value *Exc = Builder.CreateCall(llvm_eh_exception, "exc");
585     // We are required to emit this call to satisfy LLVM, even
586     // though we don't use the result.
587     Args.clear();
588     Args.push_back(Exc);
589     Args.push_back(Personality);
590     Args.push_back(llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext),
591                                           0));
592     Builder.CreateCall(llvm_eh_selector, Args.begin(), Args.end());
593     Builder.CreateStore(Exc, RethrowPtr);
594     EmitBranchThroughCleanup(FinallyRethrow);
595 
596     CodeGenFunction::CleanupBlockInfo Info = PopCleanupBlock();
597 
598     EmitBlock(MatchEnd);
599 
600     llvm::BasicBlock *Cont = createBasicBlock("invoke.cont");
601     Builder.CreateInvoke(getEndCatchFn(*this),
602                          Cont, TerminateHandler,
603                          Args.begin(), Args.begin());
604     EmitBlock(Cont);
605     if (Info.SwitchBlock)
606       EmitBlock(Info.SwitchBlock);
607     if (Info.EndBlock)
608       EmitBlock(Info.EndBlock);
609 
610     Exc = Builder.CreateCall(llvm_eh_exception, "exc");
611     Builder.CreateStore(Exc, RethrowPtr);
612     EmitBranchThroughCleanup(FinallyRethrow);
613 
614     if (Next)
615       EmitBlock(Next);
616   }
617   if (!HasCatchAll) {
618     Builder.CreateStore(Exc, RethrowPtr);
619     EmitBranchThroughCleanup(FinallyRethrow);
620   }
621 
622   CodeGenFunction::CleanupBlockInfo Info = PopCleanupBlock();
623 
624   setInvokeDest(PrevLandingPad);
625 
626   EmitBlock(FinallyBlock);
627 
628   if (Info.SwitchBlock)
629     EmitBlock(Info.SwitchBlock);
630   if (Info.EndBlock)
631     EmitBlock(Info.EndBlock);
632 
633   // Branch around the rethrow code.
634   EmitBranch(FinallyEnd);
635 
636   EmitBlock(FinallyRethrow);
637   // FIXME: Eventually we can chain the handlers together and just do a call
638   // here.
639   if (getInvokeDest()) {
640     llvm::BasicBlock *Cont = createBasicBlock("invoke.cont");
641     Builder.CreateInvoke(getUnwindResumeOrRethrowFn(*this), Cont,
642                          getInvokeDest(),
643                          Builder.CreateLoad(RethrowPtr));
644     EmitBlock(Cont);
645   } else
646     Builder.CreateCall(getUnwindResumeOrRethrowFn(*this),
647                        Builder.CreateLoad(RethrowPtr));
648 
649   Builder.CreateUnreachable();
650 
651   EmitBlock(FinallyEnd);
652 }
653 
654 CodeGenFunction::EHCleanupBlock::~EHCleanupBlock() {
655   llvm::BasicBlock *Cont1 = CGF.createBasicBlock("cont");
656   CGF.EmitBranch(Cont1);
657   CGF.setInvokeDest(PreviousInvokeDest);
658 
659 
660   CGF.EmitBlock(CleanupHandler);
661 
662   llvm::Constant *Personality =
663     CGF.CGM.CreateRuntimeFunction(llvm::FunctionType::get(llvm::Type::getInt32Ty
664                                                           (CGF.VMContext),
665                                                           true),
666                                   "__gxx_personality_v0");
667   Personality = llvm::ConstantExpr::getBitCast(Personality, CGF.PtrToInt8Ty);
668   llvm::Value *llvm_eh_exception =
669     CGF.CGM.getIntrinsic(llvm::Intrinsic::eh_exception);
670   llvm::Value *llvm_eh_selector =
671     CGF.CGM.getIntrinsic(llvm::Intrinsic::eh_selector);
672 
673   llvm::Value *Exc = CGF.Builder.CreateCall(llvm_eh_exception, "exc");
674   const llvm::IntegerType *Int8Ty;
675   const llvm::PointerType *PtrToInt8Ty;
676   Int8Ty = llvm::Type::getInt8Ty(CGF.VMContext);
677   // C string type.  Used in lots of places.
678   PtrToInt8Ty = llvm::PointerType::getUnqual(Int8Ty);
679   llvm::Constant *Null = llvm::ConstantPointerNull::get(PtrToInt8Ty);
680   llvm::SmallVector<llvm::Value*, 8> Args;
681   Args.clear();
682   Args.push_back(Exc);
683   Args.push_back(Personality);
684   Args.push_back(Null);
685   CGF.Builder.CreateCall(llvm_eh_selector, Args.begin(), Args.end());
686 
687   CGF.EmitBlock(CleanupEntryBB);
688 
689   CGF.EmitBlock(Cont1);
690 
691   if (CGF.getInvokeDest()) {
692     llvm::BasicBlock *Cont = CGF.createBasicBlock("invoke.cont");
693     CGF.Builder.CreateInvoke(getUnwindResumeOrRethrowFn(CGF), Cont,
694                              CGF.getInvokeDest(), Exc);
695     CGF.EmitBlock(Cont);
696   } else
697     CGF.Builder.CreateCall(getUnwindResumeOrRethrowFn(CGF), Exc);
698 
699   CGF.Builder.CreateUnreachable();
700 
701   CGF.EmitBlock(Cont);
702   if (CGF.Exceptions)
703     CGF.setInvokeDest(CleanupHandler);
704 }
705 
706 llvm::BasicBlock *CodeGenFunction::getTerminateHandler() {
707   if (TerminateHandler)
708     return TerminateHandler;
709 
710   llvm::BasicBlock *Cont = 0;
711 
712   if (HaveInsertPoint()) {
713     Cont = createBasicBlock("cont");
714     EmitBranch(Cont);
715   }
716 
717   llvm::Constant *Personality =
718     CGM.CreateRuntimeFunction(llvm::FunctionType::get(llvm::Type::getInt32Ty
719                                                       (VMContext),
720                                                       true),
721                               "__gxx_personality_v0");
722   Personality = llvm::ConstantExpr::getBitCast(Personality, PtrToInt8Ty);
723   llvm::Value *llvm_eh_exception =
724     CGM.getIntrinsic(llvm::Intrinsic::eh_exception);
725   llvm::Value *llvm_eh_selector =
726     CGM.getIntrinsic(llvm::Intrinsic::eh_selector);
727 
728   // Set up terminate handler
729   TerminateHandler = createBasicBlock("terminate.handler");
730   EmitBlock(TerminateHandler);
731   llvm::Value *Exc = Builder.CreateCall(llvm_eh_exception, "exc");
732   // We are required to emit this call to satisfy LLVM, even
733   // though we don't use the result.
734   llvm::SmallVector<llvm::Value*, 8> Args;
735   Args.push_back(Exc);
736   Args.push_back(Personality);
737   Args.push_back(llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext),
738                                         1));
739   Builder.CreateCall(llvm_eh_selector, Args.begin(), Args.end());
740   llvm::CallInst *TerminateCall =
741     Builder.CreateCall(getTerminateFn(*this));
742   TerminateCall->setDoesNotReturn();
743   TerminateCall->setDoesNotThrow();
744   Builder.CreateUnreachable();
745 
746   // Clear the insertion point to indicate we are in unreachable code.
747   Builder.ClearInsertionPoint();
748 
749   if (Cont)
750     EmitBlock(Cont);
751 
752   return TerminateHandler;
753 }
754