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Anders Carlsson756b5c42009-10-30 01:42:31 +00001//===--- 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
Mike Stump2bf701e2009-11-20 23:44:51 +000014#include "clang/AST/StmtCXX.h"
15
16#include "llvm/Intrinsics.h"
John McCallf1549f62010-07-06 01:34:17 +000017#include "llvm/Support/CallSite.h"
Mike Stump2bf701e2009-11-20 23:44:51 +000018
Anders Carlsson756b5c42009-10-30 01:42:31 +000019#include "CodeGenFunction.h"
John McCallf1549f62010-07-06 01:34:17 +000020#include "CGException.h"
21
Anders Carlsson756b5c42009-10-30 01:42:31 +000022using namespace clang;
23using namespace CodeGen;
24
John McCallf1549f62010-07-06 01:34:17 +000025/// Push an entry of the given size onto this protected-scope stack.
26char *EHScopeStack::allocate(size_t Size) {
27 if (!StartOfBuffer) {
28 unsigned Capacity = 1024;
29 while (Capacity < Size) Capacity *= 2;
30 StartOfBuffer = new char[Capacity];
31 StartOfData = EndOfBuffer = StartOfBuffer + Capacity;
32 } else if (static_cast<size_t>(StartOfData - StartOfBuffer) < Size) {
33 unsigned CurrentCapacity = EndOfBuffer - StartOfBuffer;
34 unsigned UsedCapacity = CurrentCapacity - (StartOfData - StartOfBuffer);
35
36 unsigned NewCapacity = CurrentCapacity;
37 do {
38 NewCapacity *= 2;
39 } while (NewCapacity < UsedCapacity + Size);
40
41 char *NewStartOfBuffer = new char[NewCapacity];
42 char *NewEndOfBuffer = NewStartOfBuffer + NewCapacity;
43 char *NewStartOfData = NewEndOfBuffer - UsedCapacity;
44 memcpy(NewStartOfData, StartOfData, UsedCapacity);
45 delete [] StartOfBuffer;
46 StartOfBuffer = NewStartOfBuffer;
47 EndOfBuffer = NewEndOfBuffer;
48 StartOfData = NewStartOfData;
49 }
50
51 assert(StartOfBuffer + Size <= StartOfData);
52 StartOfData -= Size;
53 return StartOfData;
54}
55
56EHScopeStack::stable_iterator
57EHScopeStack::getEnclosingEHCleanup(iterator it) const {
58 assert(it != end());
59 do {
60 if (isa<EHCleanupScope>(*it)) {
61 if (cast<EHCleanupScope>(*it).isEHCleanup())
62 return stabilize(it);
63 return cast<EHCleanupScope>(*it).getEnclosingEHCleanup();
64 }
John McCallda65ea82010-07-13 20:32:21 +000065 if (isa<EHLazyCleanupScope>(*it)) {
66 if (cast<EHLazyCleanupScope>(*it).isEHCleanup())
67 return stabilize(it);
68 return cast<EHLazyCleanupScope>(*it).getEnclosingEHCleanup();
69 }
John McCallf1549f62010-07-06 01:34:17 +000070 ++it;
71 } while (it != end());
72 return stable_end();
73}
74
75
John McCallda65ea82010-07-13 20:32:21 +000076void *EHScopeStack::pushLazyCleanup(CleanupKind Kind, size_t Size) {
77 assert(((Size % sizeof(void*)) == 0) && "cleanup type is misaligned");
78 char *Buffer = allocate(EHLazyCleanupScope::getSizeForCleanupSize(Size));
79 bool IsNormalCleanup = Kind != EHCleanup;
80 bool IsEHCleanup = Kind != NormalCleanup;
81 EHLazyCleanupScope *Scope =
82 new (Buffer) EHLazyCleanupScope(IsNormalCleanup,
83 IsEHCleanup,
84 Size,
85 BranchFixups.size(),
86 InnermostNormalCleanup,
87 InnermostEHCleanup);
88 if (IsNormalCleanup)
89 InnermostNormalCleanup = stable_begin();
90 if (IsEHCleanup)
91 InnermostEHCleanup = stable_begin();
92
93 return Scope->getCleanupBuffer();
94}
95
John McCallf1549f62010-07-06 01:34:17 +000096void EHScopeStack::pushCleanup(llvm::BasicBlock *NormalEntry,
97 llvm::BasicBlock *NormalExit,
98 llvm::BasicBlock *EHEntry,
99 llvm::BasicBlock *EHExit) {
100 char *Buffer = allocate(EHCleanupScope::getSize());
101 new (Buffer) EHCleanupScope(BranchFixups.size(),
102 InnermostNormalCleanup,
103 InnermostEHCleanup,
104 NormalEntry, NormalExit, EHEntry, EHExit);
105 if (NormalEntry)
106 InnermostNormalCleanup = stable_begin();
107 if (EHEntry)
108 InnermostEHCleanup = stable_begin();
109}
110
111void EHScopeStack::popCleanup() {
112 assert(!empty() && "popping exception stack when not empty");
113
John McCallda65ea82010-07-13 20:32:21 +0000114 if (isa<EHLazyCleanupScope>(*begin())) {
115 EHLazyCleanupScope &Cleanup = cast<EHLazyCleanupScope>(*begin());
116 InnermostNormalCleanup = Cleanup.getEnclosingNormalCleanup();
117 InnermostEHCleanup = Cleanup.getEnclosingEHCleanup();
118 StartOfData += Cleanup.getAllocatedSize();
119 } else {
120 assert(isa<EHCleanupScope>(*begin()));
121 EHCleanupScope &Cleanup = cast<EHCleanupScope>(*begin());
122 InnermostNormalCleanup = Cleanup.getEnclosingNormalCleanup();
123 InnermostEHCleanup = Cleanup.getEnclosingEHCleanup();
124 StartOfData += EHCleanupScope::getSize();
125 }
John McCallf1549f62010-07-06 01:34:17 +0000126
127 // Check whether we can shrink the branch-fixups stack.
128 if (!BranchFixups.empty()) {
129 // If we no longer have any normal cleanups, all the fixups are
130 // complete.
131 if (!hasNormalCleanups())
132 BranchFixups.clear();
133
134 // Otherwise we can still trim out unnecessary nulls.
135 else
136 popNullFixups();
137 }
138}
139
140EHFilterScope *EHScopeStack::pushFilter(unsigned NumFilters) {
141 char *Buffer = allocate(EHFilterScope::getSizeForNumFilters(NumFilters));
142 CatchDepth++;
143 return new (Buffer) EHFilterScope(NumFilters);
144}
145
146void EHScopeStack::popFilter() {
147 assert(!empty() && "popping exception stack when not empty");
148
149 EHFilterScope &Filter = cast<EHFilterScope>(*begin());
150 StartOfData += EHFilterScope::getSizeForNumFilters(Filter.getNumFilters());
151
152 assert(CatchDepth > 0 && "mismatched filter push/pop");
153 CatchDepth--;
154}
155
156EHCatchScope *EHScopeStack::pushCatch(unsigned NumHandlers) {
157 char *Buffer = allocate(EHCatchScope::getSizeForNumHandlers(NumHandlers));
158 CatchDepth++;
159 return new (Buffer) EHCatchScope(NumHandlers);
160}
161
162void EHScopeStack::pushTerminate() {
163 char *Buffer = allocate(EHTerminateScope::getSize());
164 CatchDepth++;
165 new (Buffer) EHTerminateScope();
166}
167
168/// Remove any 'null' fixups on the stack. However, we can't pop more
169/// fixups than the fixup depth on the innermost normal cleanup, or
170/// else fixups that we try to add to that cleanup will end up in the
171/// wrong place. We *could* try to shrink fixup depths, but that's
172/// actually a lot of work for little benefit.
173void EHScopeStack::popNullFixups() {
174 // We expect this to only be called when there's still an innermost
175 // normal cleanup; otherwise there really shouldn't be any fixups.
176 assert(hasNormalCleanups());
177
178 EHScopeStack::iterator it = find(InnermostNormalCleanup);
John McCallda65ea82010-07-13 20:32:21 +0000179 unsigned MinSize;
180 if (isa<EHCleanupScope>(*it))
181 MinSize = cast<EHCleanupScope>(*it).getFixupDepth();
182 else
183 MinSize = cast<EHLazyCleanupScope>(*it).getFixupDepth();
John McCallf1549f62010-07-06 01:34:17 +0000184 assert(BranchFixups.size() >= MinSize && "fixup stack out of order");
185
186 while (BranchFixups.size() > MinSize &&
187 BranchFixups.back().Destination == 0)
188 BranchFixups.pop_back();
189}
190
191void EHScopeStack::resolveBranchFixups(llvm::BasicBlock *Dest) {
192 assert(Dest && "null block passed to resolveBranchFixups");
193
194 if (BranchFixups.empty()) return;
195 assert(hasNormalCleanups() &&
196 "branch fixups exist with no normal cleanups on stack");
197
198 for (unsigned I = 0, E = BranchFixups.size(); I != E; ++I)
199 if (BranchFixups[I].Destination == Dest)
200 BranchFixups[I].Destination = 0;
201
202 popNullFixups();
203}
204
Anders Carlssond3379292009-10-30 02:27:02 +0000205static llvm::Constant *getAllocateExceptionFn(CodeGenFunction &CGF) {
206 // void *__cxa_allocate_exception(size_t thrown_size);
207 const llvm::Type *SizeTy = CGF.ConvertType(CGF.getContext().getSizeType());
208 std::vector<const llvm::Type*> Args(1, SizeTy);
Mike Stump8755ec32009-12-10 00:06:18 +0000209
210 const llvm::FunctionType *FTy =
Anders Carlssond3379292009-10-30 02:27:02 +0000211 llvm::FunctionType::get(llvm::Type::getInt8PtrTy(CGF.getLLVMContext()),
212 Args, false);
Mike Stump8755ec32009-12-10 00:06:18 +0000213
Anders Carlssond3379292009-10-30 02:27:02 +0000214 return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_allocate_exception");
215}
216
Mike Stump99533832009-12-02 07:41:41 +0000217static llvm::Constant *getFreeExceptionFn(CodeGenFunction &CGF) {
218 // void __cxa_free_exception(void *thrown_exception);
219 const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGF.getLLVMContext());
220 std::vector<const llvm::Type*> Args(1, Int8PtrTy);
Mike Stump8755ec32009-12-10 00:06:18 +0000221
222 const llvm::FunctionType *FTy =
Mike Stump99533832009-12-02 07:41:41 +0000223 llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()),
224 Args, false);
Mike Stump8755ec32009-12-10 00:06:18 +0000225
Mike Stump99533832009-12-02 07:41:41 +0000226 return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_free_exception");
227}
228
Anders Carlssond3379292009-10-30 02:27:02 +0000229static llvm::Constant *getThrowFn(CodeGenFunction &CGF) {
Mike Stump8755ec32009-12-10 00:06:18 +0000230 // void __cxa_throw(void *thrown_exception, std::type_info *tinfo,
Mike Stump99533832009-12-02 07:41:41 +0000231 // void (*dest) (void *));
Anders Carlssond3379292009-10-30 02:27:02 +0000232
233 const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGF.getLLVMContext());
234 std::vector<const llvm::Type*> Args(3, Int8PtrTy);
Mike Stump8755ec32009-12-10 00:06:18 +0000235
236 const llvm::FunctionType *FTy =
Mike Stumpb4eea692009-11-20 00:56:31 +0000237 llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()),
238 Args, false);
Mike Stump8755ec32009-12-10 00:06:18 +0000239
Anders Carlssond3379292009-10-30 02:27:02 +0000240 return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_throw");
241}
242
Mike Stumpb4eea692009-11-20 00:56:31 +0000243static llvm::Constant *getReThrowFn(CodeGenFunction &CGF) {
Mike Stump99533832009-12-02 07:41:41 +0000244 // void __cxa_rethrow();
Mike Stumpb4eea692009-11-20 00:56:31 +0000245
Mike Stump8755ec32009-12-10 00:06:18 +0000246 const llvm::FunctionType *FTy =
Mike Stumpb4eea692009-11-20 00:56:31 +0000247 llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()), false);
Mike Stump8755ec32009-12-10 00:06:18 +0000248
Mike Stumpb4eea692009-11-20 00:56:31 +0000249 return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_rethrow");
250}
251
John McCallf1549f62010-07-06 01:34:17 +0000252static llvm::Constant *getGetExceptionPtrFn(CodeGenFunction &CGF) {
253 // void *__cxa_get_exception_ptr(void*);
254 const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGF.getLLVMContext());
255 std::vector<const llvm::Type*> Args(1, Int8PtrTy);
256
257 const llvm::FunctionType *FTy =
258 llvm::FunctionType::get(Int8PtrTy, Args, false);
259
260 return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_get_exception_ptr");
261}
262
Mike Stump2bf701e2009-11-20 23:44:51 +0000263static llvm::Constant *getBeginCatchFn(CodeGenFunction &CGF) {
John McCallf1549f62010-07-06 01:34:17 +0000264 // void *__cxa_begin_catch(void*);
Mike Stump2bf701e2009-11-20 23:44:51 +0000265
266 const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGF.getLLVMContext());
267 std::vector<const llvm::Type*> Args(1, Int8PtrTy);
Mike Stump8755ec32009-12-10 00:06:18 +0000268
269 const llvm::FunctionType *FTy =
Mike Stump0f590be2009-12-01 03:41:18 +0000270 llvm::FunctionType::get(Int8PtrTy, Args, false);
Mike Stump8755ec32009-12-10 00:06:18 +0000271
Mike Stump2bf701e2009-11-20 23:44:51 +0000272 return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_begin_catch");
273}
274
275static llvm::Constant *getEndCatchFn(CodeGenFunction &CGF) {
Mike Stump99533832009-12-02 07:41:41 +0000276 // void __cxa_end_catch();
Mike Stump2bf701e2009-11-20 23:44:51 +0000277
Mike Stump8755ec32009-12-10 00:06:18 +0000278 const llvm::FunctionType *FTy =
Mike Stump2bf701e2009-11-20 23:44:51 +0000279 llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()), false);
Mike Stump8755ec32009-12-10 00:06:18 +0000280
Mike Stump2bf701e2009-11-20 23:44:51 +0000281 return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_end_catch");
282}
283
Mike Stumpcce3d4f2009-12-07 23:38:24 +0000284static llvm::Constant *getUnexpectedFn(CodeGenFunction &CGF) {
285 // void __cxa_call_unexepcted(void *thrown_exception);
286
287 const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGF.getLLVMContext());
288 std::vector<const llvm::Type*> Args(1, Int8PtrTy);
Mike Stump8755ec32009-12-10 00:06:18 +0000289
290 const llvm::FunctionType *FTy =
Mike Stumpcce3d4f2009-12-07 23:38:24 +0000291 llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()),
292 Args, false);
Mike Stump8755ec32009-12-10 00:06:18 +0000293
Mike Stumpcce3d4f2009-12-07 23:38:24 +0000294 return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_call_unexpected");
295}
296
Douglas Gregor86a3a032010-05-16 01:24:12 +0000297llvm::Constant *CodeGenFunction::getUnwindResumeOrRethrowFn() {
298 const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(getLLVMContext());
Mike Stump0f590be2009-12-01 03:41:18 +0000299 std::vector<const llvm::Type*> Args(1, Int8PtrTy);
Mike Stump8755ec32009-12-10 00:06:18 +0000300
301 const llvm::FunctionType *FTy =
Douglas Gregor86a3a032010-05-16 01:24:12 +0000302 llvm::FunctionType::get(llvm::Type::getVoidTy(getLLVMContext()), Args,
Mike Stump0f590be2009-12-01 03:41:18 +0000303 false);
Mike Stump8755ec32009-12-10 00:06:18 +0000304
Douglas Gregor86a3a032010-05-16 01:24:12 +0000305 if (CGM.getLangOptions().SjLjExceptions)
306 return CGM.CreateRuntimeFunction(FTy, "_Unwind_SjLj_Resume");
307 return CGM.CreateRuntimeFunction(FTy, "_Unwind_Resume_or_Rethrow");
Mike Stump0f590be2009-12-01 03:41:18 +0000308}
309
Mike Stump99533832009-12-02 07:41:41 +0000310static llvm::Constant *getTerminateFn(CodeGenFunction &CGF) {
311 // void __terminate();
312
Mike Stump8755ec32009-12-10 00:06:18 +0000313 const llvm::FunctionType *FTy =
Mike Stump99533832009-12-02 07:41:41 +0000314 llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()), false);
Mike Stump8755ec32009-12-10 00:06:18 +0000315
David Chisnall79a9ad82010-05-17 13:49:20 +0000316 return CGF.CGM.CreateRuntimeFunction(FTy,
317 CGF.CGM.getLangOptions().CPlusPlus ? "_ZSt9terminatev" : "abort");
318}
319
John McCall8262b6a2010-07-17 00:43:08 +0000320static llvm::Constant *getCatchallRethrowFn(CodeGenFunction &CGF,
321 const char *Name) {
322 const llvm::Type *Int8PtrTy =
323 llvm::Type::getInt8PtrTy(CGF.getLLVMContext());
324 std::vector<const llvm::Type*> Args(1, Int8PtrTy);
325
326 const llvm::Type *VoidTy = llvm::Type::getVoidTy(CGF.getLLVMContext());
327 const llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, Args, false);
328
329 return CGF.CGM.CreateRuntimeFunction(FTy, Name);
John McCallf1549f62010-07-06 01:34:17 +0000330}
331
John McCall8262b6a2010-07-17 00:43:08 +0000332const EHPersonality EHPersonality::GNU_C("__gcc_personality_v0");
333const EHPersonality EHPersonality::NeXT_ObjC("__objc_personality_v0");
334const EHPersonality EHPersonality::GNU_CPlusPlus("__gxx_personality_v0");
335const EHPersonality EHPersonality::GNU_CPlusPlus_SJLJ("__gxx_personality_sj0");
336const EHPersonality EHPersonality::GNU_ObjC("__gnu_objc_personality_v0",
337 "objc_exception_throw");
338
339static const EHPersonality &getCPersonality(const LangOptions &L) {
340 return EHPersonality::GNU_C;
341}
342
343static const EHPersonality &getObjCPersonality(const LangOptions &L) {
344 if (L.NeXTRuntime) {
345 if (L.ObjCNonFragileABI) return EHPersonality::NeXT_ObjC;
346 else return getCPersonality(L);
John McCallf1549f62010-07-06 01:34:17 +0000347 } else {
John McCall8262b6a2010-07-17 00:43:08 +0000348 return EHPersonality::GNU_ObjC;
John McCallf1549f62010-07-06 01:34:17 +0000349 }
350}
351
John McCall8262b6a2010-07-17 00:43:08 +0000352static const EHPersonality &getCXXPersonality(const LangOptions &L) {
353 if (L.SjLjExceptions)
354 return EHPersonality::GNU_CPlusPlus_SJLJ;
John McCallf1549f62010-07-06 01:34:17 +0000355 else
John McCall8262b6a2010-07-17 00:43:08 +0000356 return EHPersonality::GNU_CPlusPlus;
John McCallf1549f62010-07-06 01:34:17 +0000357}
358
359/// Determines the personality function to use when both C++
360/// and Objective-C exceptions are being caught.
John McCall8262b6a2010-07-17 00:43:08 +0000361static const EHPersonality &getObjCXXPersonality(const LangOptions &L) {
John McCallf1549f62010-07-06 01:34:17 +0000362 // The ObjC personality defers to the C++ personality for non-ObjC
363 // handlers. Unlike the C++ case, we use the same personality
364 // function on targets using (backend-driven) SJLJ EH.
John McCall8262b6a2010-07-17 00:43:08 +0000365 if (L.NeXTRuntime) {
366 if (L.ObjCNonFragileABI)
367 return EHPersonality::NeXT_ObjC;
John McCallf1549f62010-07-06 01:34:17 +0000368
369 // In the fragile ABI, just use C++ exception handling and hope
370 // they're not doing crazy exception mixing.
371 else
John McCall8262b6a2010-07-17 00:43:08 +0000372 return getCXXPersonality(L);
Chandler Carruthdcf22ad2010-05-17 20:58:49 +0000373 }
David Chisnall79a9ad82010-05-17 13:49:20 +0000374
John McCall8262b6a2010-07-17 00:43:08 +0000375 // The GNU runtime's personality function inherently doesn't support
376 // mixed EH. Use the C++ personality just to avoid returning null.
377 return getCXXPersonality(L);
John McCallf1549f62010-07-06 01:34:17 +0000378}
379
John McCall8262b6a2010-07-17 00:43:08 +0000380const EHPersonality &EHPersonality::get(const LangOptions &L) {
381 if (L.CPlusPlus && L.ObjC1)
382 return getObjCXXPersonality(L);
383 else if (L.CPlusPlus)
384 return getCXXPersonality(L);
385 else if (L.ObjC1)
386 return getObjCPersonality(L);
John McCallf1549f62010-07-06 01:34:17 +0000387 else
John McCall8262b6a2010-07-17 00:43:08 +0000388 return getCPersonality(L);
389}
John McCallf1549f62010-07-06 01:34:17 +0000390
John McCall8262b6a2010-07-17 00:43:08 +0000391static llvm::Constant *getPersonalityFn(CodeGenFunction &CGF,
392 const EHPersonality &Personality) {
393 const char *Name = Personality.getPersonalityFnName();
394
395 llvm::Constant *Fn =
John McCallf1549f62010-07-06 01:34:17 +0000396 CGF.CGM.CreateRuntimeFunction(llvm::FunctionType::get(
397 llvm::Type::getInt32Ty(
398 CGF.CGM.getLLVMContext()),
399 true),
400 Name);
John McCall8262b6a2010-07-17 00:43:08 +0000401 return llvm::ConstantExpr::getBitCast(Fn, CGF.CGM.PtrToInt8Ty);
John McCallf1549f62010-07-06 01:34:17 +0000402}
403
404/// Returns the value to inject into a selector to indicate the
405/// presence of a catch-all.
406static llvm::Constant *getCatchAllValue(CodeGenFunction &CGF) {
407 // Possibly we should use @llvm.eh.catch.all.value here.
408 return llvm::ConstantPointerNull::get(CGF.CGM.PtrToInt8Ty);
409}
410
411/// Returns the value to inject into a selector to indicate the
412/// presence of a cleanup.
413static llvm::Constant *getCleanupValue(CodeGenFunction &CGF) {
414 return llvm::ConstantInt::get(CGF.Builder.getInt32Ty(), 0);
Mike Stump99533832009-12-02 07:41:41 +0000415}
416
John McCall09faeab2010-07-13 21:17:51 +0000417namespace {
418 /// A cleanup to free the exception object if its initialization
419 /// throws.
420 struct FreeExceptionCleanup : EHScopeStack::LazyCleanup {
421 FreeExceptionCleanup(llvm::Value *ShouldFreeVar,
422 llvm::Value *ExnLocVar)
423 : ShouldFreeVar(ShouldFreeVar), ExnLocVar(ExnLocVar) {}
424
425 llvm::Value *ShouldFreeVar;
426 llvm::Value *ExnLocVar;
427
428 void Emit(CodeGenFunction &CGF, bool IsForEH) {
429 llvm::BasicBlock *FreeBB = CGF.createBasicBlock("free-exnobj");
430 llvm::BasicBlock *DoneBB = CGF.createBasicBlock("free-exnobj.done");
431
432 llvm::Value *ShouldFree = CGF.Builder.CreateLoad(ShouldFreeVar,
433 "should-free-exnobj");
434 CGF.Builder.CreateCondBr(ShouldFree, FreeBB, DoneBB);
435 CGF.EmitBlock(FreeBB);
436 llvm::Value *ExnLocLocal = CGF.Builder.CreateLoad(ExnLocVar, "exnobj");
437 CGF.Builder.CreateCall(getFreeExceptionFn(CGF), ExnLocLocal)
438 ->setDoesNotThrow();
439 CGF.EmitBlock(DoneBB);
440 }
441 };
442}
443
John McCallac418162010-04-22 01:10:34 +0000444// Emits an exception expression into the given location. This
445// differs from EmitAnyExprToMem only in that, if a final copy-ctor
446// call is required, an exception within that copy ctor causes
447// std::terminate to be invoked.
448static void EmitAnyExprToExn(CodeGenFunction &CGF, const Expr *E,
449 llvm::Value *ExnLoc) {
450 // We want to release the allocated exception object if this
451 // expression throws. We do this by pushing an EH-only cleanup
452 // block which, furthermore, deactivates itself after the expression
453 // is complete.
454 llvm::AllocaInst *ShouldFreeVar =
455 CGF.CreateTempAlloca(llvm::Type::getInt1Ty(CGF.getLLVMContext()),
456 "should-free-exnobj.var");
457 CGF.InitTempAlloca(ShouldFreeVar,
458 llvm::ConstantInt::getFalse(CGF.getLLVMContext()));
Mike Stump0f590be2009-12-01 03:41:18 +0000459
John McCallac418162010-04-22 01:10:34 +0000460 // A variable holding the exception pointer. This is necessary
461 // because the throw expression does not necessarily dominate the
462 // cleanup, for example if it appears in a conditional expression.
463 llvm::AllocaInst *ExnLocVar =
464 CGF.CreateTempAlloca(ExnLoc->getType(), "exnobj.var");
Mike Stump8755ec32009-12-10 00:06:18 +0000465
John McCallf1549f62010-07-06 01:34:17 +0000466 // Make sure the exception object is cleaned up if there's an
467 // exception during initialization.
John McCall09faeab2010-07-13 21:17:51 +0000468 // FIXME: stmt expressions might require this to be a normal
469 // cleanup, too.
470 CGF.EHStack.pushLazyCleanup<FreeExceptionCleanup>(EHCleanup,
471 ShouldFreeVar,
472 ExnLocVar);
John McCallf1549f62010-07-06 01:34:17 +0000473 EHScopeStack::stable_iterator Cleanup = CGF.EHStack.stable_begin();
John McCallac418162010-04-22 01:10:34 +0000474
475 CGF.Builder.CreateStore(ExnLoc, ExnLocVar);
476 CGF.Builder.CreateStore(llvm::ConstantInt::getTrue(CGF.getLLVMContext()),
477 ShouldFreeVar);
478
479 // __cxa_allocate_exception returns a void*; we need to cast this
480 // to the appropriate type for the object.
481 const llvm::Type *Ty = CGF.ConvertType(E->getType())->getPointerTo();
482 llvm::Value *TypedExnLoc = CGF.Builder.CreateBitCast(ExnLoc, Ty);
483
484 // FIXME: this isn't quite right! If there's a final unelided call
485 // to a copy constructor, then according to [except.terminate]p1 we
486 // must call std::terminate() if that constructor throws, because
487 // technically that copy occurs after the exception expression is
488 // evaluated but before the exception is caught. But the best way
489 // to handle that is to teach EmitAggExpr to do the final copy
490 // differently if it can't be elided.
491 CGF.EmitAnyExprToMem(E, TypedExnLoc, /*Volatile*/ false);
492
493 CGF.Builder.CreateStore(llvm::ConstantInt::getFalse(CGF.getLLVMContext()),
494 ShouldFreeVar);
495
John McCallf1549f62010-07-06 01:34:17 +0000496 // Technically, the exception object is like a temporary; it has to
497 // be cleaned up when its full-expression is complete.
498 // Unfortunately, the AST represents full-expressions by creating a
499 // CXXExprWithTemporaries, which it only does when there are actually
500 // temporaries.
501 //
502 // If any cleanups have been added since we pushed ours, they must
503 // be from temporaries; this will get popped at the same time.
504 // Otherwise we need to pop ours off. FIXME: this is very brittle.
505 if (Cleanup == CGF.EHStack.stable_begin())
506 CGF.PopCleanupBlock();
Mike Stump0f590be2009-12-01 03:41:18 +0000507}
508
John McCallf1549f62010-07-06 01:34:17 +0000509llvm::Value *CodeGenFunction::getExceptionSlot() {
510 if (!ExceptionSlot) {
511 const llvm::Type *i8p = llvm::Type::getInt8PtrTy(getLLVMContext());
512 ExceptionSlot = CreateTempAlloca(i8p, "exn.slot");
Mike Stump0f590be2009-12-01 03:41:18 +0000513 }
John McCallf1549f62010-07-06 01:34:17 +0000514 return ExceptionSlot;
Mike Stump0f590be2009-12-01 03:41:18 +0000515}
516
Anders Carlsson756b5c42009-10-30 01:42:31 +0000517void CodeGenFunction::EmitCXXThrowExpr(const CXXThrowExpr *E) {
Anders Carlssond3379292009-10-30 02:27:02 +0000518 if (!E->getSubExpr()) {
Douglas Gregor1eb2e592010-05-16 00:44:00 +0000519 if (getInvokeDest()) {
John McCallf1549f62010-07-06 01:34:17 +0000520 Builder.CreateInvoke(getReThrowFn(*this),
521 getUnreachableBlock(),
522 getInvokeDest())
Douglas Gregor1eb2e592010-05-16 00:44:00 +0000523 ->setDoesNotReturn();
John McCallf1549f62010-07-06 01:34:17 +0000524 } else {
Douglas Gregor1eb2e592010-05-16 00:44:00 +0000525 Builder.CreateCall(getReThrowFn(*this))->setDoesNotReturn();
John McCallf1549f62010-07-06 01:34:17 +0000526 Builder.CreateUnreachable();
527 }
Douglas Gregor1eb2e592010-05-16 00:44:00 +0000528
529 // Clear the insertion point to indicate we are in unreachable code.
530 Builder.ClearInsertionPoint();
Anders Carlssond3379292009-10-30 02:27:02 +0000531 return;
532 }
Mike Stump8755ec32009-12-10 00:06:18 +0000533
Anders Carlssond3379292009-10-30 02:27:02 +0000534 QualType ThrowType = E->getSubExpr()->getType();
Mike Stump8755ec32009-12-10 00:06:18 +0000535
Anders Carlssond3379292009-10-30 02:27:02 +0000536 // Now allocate the exception object.
537 const llvm::Type *SizeTy = ConvertType(getContext().getSizeType());
John McCall3d3ec1c2010-04-21 10:05:39 +0000538 uint64_t TypeSize = getContext().getTypeSizeInChars(ThrowType).getQuantity();
Mike Stump8755ec32009-12-10 00:06:18 +0000539
Anders Carlssond3379292009-10-30 02:27:02 +0000540 llvm::Constant *AllocExceptionFn = getAllocateExceptionFn(*this);
John McCallf1549f62010-07-06 01:34:17 +0000541 llvm::CallInst *ExceptionPtr =
Mike Stump8755ec32009-12-10 00:06:18 +0000542 Builder.CreateCall(AllocExceptionFn,
Anders Carlssond3379292009-10-30 02:27:02 +0000543 llvm::ConstantInt::get(SizeTy, TypeSize),
544 "exception");
John McCallf1549f62010-07-06 01:34:17 +0000545 ExceptionPtr->setDoesNotThrow();
Anders Carlsson8370c582009-12-11 00:32:37 +0000546
John McCallac418162010-04-22 01:10:34 +0000547 EmitAnyExprToExn(*this, E->getSubExpr(), ExceptionPtr);
Mike Stump8755ec32009-12-10 00:06:18 +0000548
Anders Carlssond3379292009-10-30 02:27:02 +0000549 // Now throw the exception.
550 const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(getLLVMContext());
John McCall9dffe6f2010-04-30 01:15:21 +0000551 llvm::Constant *TypeInfo = CGM.GetAddrOfRTTIDescriptor(ThrowType, true);
John McCallac418162010-04-22 01:10:34 +0000552
553 // The address of the destructor. If the exception type has a
554 // trivial destructor (or isn't a record), we just pass null.
555 llvm::Constant *Dtor = 0;
556 if (const RecordType *RecordTy = ThrowType->getAs<RecordType>()) {
557 CXXRecordDecl *Record = cast<CXXRecordDecl>(RecordTy->getDecl());
558 if (!Record->hasTrivialDestructor()) {
Douglas Gregor1d110e02010-07-01 14:13:13 +0000559 CXXDestructorDecl *DtorD = Record->getDestructor();
John McCallac418162010-04-22 01:10:34 +0000560 Dtor = CGM.GetAddrOfCXXDestructor(DtorD, Dtor_Complete);
561 Dtor = llvm::ConstantExpr::getBitCast(Dtor, Int8PtrTy);
562 }
563 }
564 if (!Dtor) Dtor = llvm::Constant::getNullValue(Int8PtrTy);
Mike Stump8755ec32009-12-10 00:06:18 +0000565
Mike Stump0a3816e2009-12-04 01:51:45 +0000566 if (getInvokeDest()) {
Mike Stump8755ec32009-12-10 00:06:18 +0000567 llvm::InvokeInst *ThrowCall =
John McCallf1549f62010-07-06 01:34:17 +0000568 Builder.CreateInvoke3(getThrowFn(*this),
569 getUnreachableBlock(), getInvokeDest(),
Mike Stump0a3816e2009-12-04 01:51:45 +0000570 ExceptionPtr, TypeInfo, Dtor);
571 ThrowCall->setDoesNotReturn();
Mike Stump0a3816e2009-12-04 01:51:45 +0000572 } else {
Mike Stump8755ec32009-12-10 00:06:18 +0000573 llvm::CallInst *ThrowCall =
Mike Stump0a3816e2009-12-04 01:51:45 +0000574 Builder.CreateCall3(getThrowFn(*this), ExceptionPtr, TypeInfo, Dtor);
575 ThrowCall->setDoesNotReturn();
John McCallf1549f62010-07-06 01:34:17 +0000576 Builder.CreateUnreachable();
Mike Stump0a3816e2009-12-04 01:51:45 +0000577 }
Mike Stump8755ec32009-12-10 00:06:18 +0000578
Anders Carlssond3379292009-10-30 02:27:02 +0000579 // Clear the insertion point to indicate we are in unreachable code.
580 Builder.ClearInsertionPoint();
Mike Stumpc2ab4862009-12-07 20:12:14 +0000581
582 // FIXME: For now, emit a dummy basic block because expr emitters in generally
583 // are not ready to handle emitting expressions at unreachable points.
584 EnsureInsertPoint();
Anders Carlsson756b5c42009-10-30 01:42:31 +0000585}
Mike Stump2bf701e2009-11-20 23:44:51 +0000586
Mike Stumpcce3d4f2009-12-07 23:38:24 +0000587void CodeGenFunction::EmitStartEHSpec(const Decl *D) {
Anders Carlssona994ee42010-02-06 23:59:05 +0000588 if (!Exceptions)
589 return;
590
Mike Stumpcce3d4f2009-12-07 23:38:24 +0000591 const FunctionDecl* FD = dyn_cast_or_null<FunctionDecl>(D);
592 if (FD == 0)
593 return;
594 const FunctionProtoType *Proto = FD->getType()->getAs<FunctionProtoType>();
595 if (Proto == 0)
596 return;
597
598 assert(!Proto->hasAnyExceptionSpec() && "function with parameter pack");
599
600 if (!Proto->hasExceptionSpec())
601 return;
602
John McCallf1549f62010-07-06 01:34:17 +0000603 unsigned NumExceptions = Proto->getNumExceptions();
604 EHFilterScope *Filter = EHStack.pushFilter(NumExceptions);
Mike Stumpcce3d4f2009-12-07 23:38:24 +0000605
John McCallf1549f62010-07-06 01:34:17 +0000606 for (unsigned I = 0; I != NumExceptions; ++I) {
607 QualType Ty = Proto->getExceptionType(I);
608 QualType ExceptType = Ty.getNonReferenceType().getUnqualifiedType();
John McCall9dffe6f2010-04-30 01:15:21 +0000609 llvm::Value *EHType = CGM.GetAddrOfRTTIDescriptor(ExceptType, true);
John McCallf1549f62010-07-06 01:34:17 +0000610 Filter->setFilter(I, EHType);
Mike Stumpcce3d4f2009-12-07 23:38:24 +0000611 }
Mike Stumpcce3d4f2009-12-07 23:38:24 +0000612}
613
614void CodeGenFunction::EmitEndEHSpec(const Decl *D) {
Anders Carlssona994ee42010-02-06 23:59:05 +0000615 if (!Exceptions)
616 return;
617
Mike Stumpcce3d4f2009-12-07 23:38:24 +0000618 const FunctionDecl* FD = dyn_cast_or_null<FunctionDecl>(D);
619 if (FD == 0)
620 return;
621 const FunctionProtoType *Proto = FD->getType()->getAs<FunctionProtoType>();
622 if (Proto == 0)
623 return;
624
625 if (!Proto->hasExceptionSpec())
626 return;
627
John McCallf1549f62010-07-06 01:34:17 +0000628 EHStack.popFilter();
Mike Stumpcce3d4f2009-12-07 23:38:24 +0000629}
630
Mike Stump2bf701e2009-11-20 23:44:51 +0000631void CodeGenFunction::EmitCXXTryStmt(const CXXTryStmt &S) {
John McCall59a70002010-07-07 06:56:46 +0000632 EnterCXXTryStmt(S);
John McCall9fc6a772010-02-19 09:25:03 +0000633 EmitStmt(S.getTryBlock());
John McCall59a70002010-07-07 06:56:46 +0000634 ExitCXXTryStmt(S);
John McCall9fc6a772010-02-19 09:25:03 +0000635}
636
John McCall59a70002010-07-07 06:56:46 +0000637void CodeGenFunction::EnterCXXTryStmt(const CXXTryStmt &S, bool IsFnTryBlock) {
John McCallf1549f62010-07-06 01:34:17 +0000638 unsigned NumHandlers = S.getNumHandlers();
639 EHCatchScope *CatchScope = EHStack.pushCatch(NumHandlers);
John McCall9fc6a772010-02-19 09:25:03 +0000640
John McCallf1549f62010-07-06 01:34:17 +0000641 for (unsigned I = 0; I != NumHandlers; ++I) {
642 const CXXCatchStmt *C = S.getHandler(I);
John McCall9fc6a772010-02-19 09:25:03 +0000643
John McCallf1549f62010-07-06 01:34:17 +0000644 llvm::BasicBlock *Handler = createBasicBlock("catch");
645 if (C->getExceptionDecl()) {
646 // FIXME: Dropping the reference type on the type into makes it
647 // impossible to correctly implement catch-by-reference
648 // semantics for pointers. Unfortunately, this is what all
649 // existing compilers do, and it's not clear that the standard
650 // personality routine is capable of doing this right. See C++ DR 388:
651 // http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#388
652 QualType CaughtType = C->getCaughtType();
653 CaughtType = CaughtType.getNonReferenceType().getUnqualifiedType();
654 llvm::Value *TypeInfo = CGM.GetAddrOfRTTIDescriptor(CaughtType, true);
655 CatchScope->setHandler(I, TypeInfo, Handler);
656 } else {
657 // No exception decl indicates '...', a catch-all.
658 CatchScope->setCatchAllHandler(I, Handler);
659 }
660 }
John McCallf1549f62010-07-06 01:34:17 +0000661}
662
663/// Check whether this is a non-EH scope, i.e. a scope which doesn't
664/// affect exception handling. Currently, the only non-EH scopes are
665/// normal-only cleanup scopes.
666static bool isNonEHScope(const EHScope &S) {
John McCallda65ea82010-07-13 20:32:21 +0000667 switch (S.getKind()) {
668 case EHScope::Cleanup:
669 return !cast<EHCleanupScope>(S).isEHCleanup();
670 case EHScope::LazyCleanup:
671 return !cast<EHLazyCleanupScope>(S).isEHCleanup();
672 case EHScope::Filter:
673 case EHScope::Catch:
674 case EHScope::Terminate:
675 return false;
676 }
677
678 // Suppress warning.
679 return false;
John McCallf1549f62010-07-06 01:34:17 +0000680}
681
682llvm::BasicBlock *CodeGenFunction::getInvokeDestImpl() {
683 assert(EHStack.requiresLandingPad());
684 assert(!EHStack.empty());
685
John McCallda65ea82010-07-13 20:32:21 +0000686 if (!Exceptions)
687 return 0;
688
John McCallf1549f62010-07-06 01:34:17 +0000689 // Check the innermost scope for a cached landing pad. If this is
690 // a non-EH cleanup, we'll check enclosing scopes in EmitLandingPad.
691 llvm::BasicBlock *LP = EHStack.begin()->getCachedLandingPad();
692 if (LP) return LP;
693
694 // Build the landing pad for this scope.
695 LP = EmitLandingPad();
696 assert(LP);
697
698 // Cache the landing pad on the innermost scope. If this is a
699 // non-EH scope, cache the landing pad on the enclosing scope, too.
700 for (EHScopeStack::iterator ir = EHStack.begin(); true; ++ir) {
701 ir->setCachedLandingPad(LP);
702 if (!isNonEHScope(*ir)) break;
703 }
704
705 return LP;
706}
707
708llvm::BasicBlock *CodeGenFunction::EmitLandingPad() {
709 assert(EHStack.requiresLandingPad());
710
711 // This function contains a hack to work around a design flaw in
712 // LLVM's EH IR which breaks semantics after inlining. This same
713 // hack is implemented in llvm-gcc.
714 //
715 // The LLVM EH abstraction is basically a thin veneer over the
716 // traditional GCC zero-cost design: for each range of instructions
717 // in the function, there is (at most) one "landing pad" with an
718 // associated chain of EH actions. A language-specific personality
719 // function interprets this chain of actions and (1) decides whether
720 // or not to resume execution at the landing pad and (2) if so,
721 // provides an integer indicating why it's stopping. In LLVM IR,
722 // the association of a landing pad with a range of instructions is
723 // achieved via an invoke instruction, the chain of actions becomes
724 // the arguments to the @llvm.eh.selector call, and the selector
725 // call returns the integer indicator. Other than the required
726 // presence of two intrinsic function calls in the landing pad,
727 // the IR exactly describes the layout of the output code.
728 //
729 // A principal advantage of this design is that it is completely
730 // language-agnostic; in theory, the LLVM optimizers can treat
731 // landing pads neutrally, and targets need only know how to lower
732 // the intrinsics to have a functioning exceptions system (assuming
733 // that platform exceptions follow something approximately like the
734 // GCC design). Unfortunately, landing pads cannot be combined in a
735 // language-agnostic way: given selectors A and B, there is no way
736 // to make a single landing pad which faithfully represents the
737 // semantics of propagating an exception first through A, then
738 // through B, without knowing how the personality will interpret the
739 // (lowered form of the) selectors. This means that inlining has no
740 // choice but to crudely chain invokes (i.e., to ignore invokes in
741 // the inlined function, but to turn all unwindable calls into
742 // invokes), which is only semantically valid if every unwind stops
743 // at every landing pad.
744 //
745 // Therefore, the invoke-inline hack is to guarantee that every
746 // landing pad has a catch-all.
747 const bool UseInvokeInlineHack = true;
748
749 for (EHScopeStack::iterator ir = EHStack.begin(); ; ) {
750 assert(ir != EHStack.end() &&
751 "stack requiring landing pad is nothing but non-EH scopes?");
752
753 // If this is a terminate scope, just use the singleton terminate
754 // landing pad.
755 if (isa<EHTerminateScope>(*ir))
756 return getTerminateLandingPad();
757
758 // If this isn't an EH scope, iterate; otherwise break out.
759 if (!isNonEHScope(*ir)) break;
760 ++ir;
761
762 // We haven't checked this scope for a cached landing pad yet.
763 if (llvm::BasicBlock *LP = ir->getCachedLandingPad())
764 return LP;
765 }
766
767 // Save the current IR generation state.
768 CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
769
John McCall8262b6a2010-07-17 00:43:08 +0000770 const EHPersonality &Personality =
771 EHPersonality::get(CGF.CGM.getLangOptions());
772
John McCallf1549f62010-07-06 01:34:17 +0000773 // Create and configure the landing pad.
774 llvm::BasicBlock *LP = createBasicBlock("lpad");
775 EmitBlock(LP);
776
777 // Save the exception pointer. It's safe to use a single exception
778 // pointer per function because EH cleanups can never have nested
779 // try/catches.
780 llvm::CallInst *Exn =
781 Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::eh_exception), "exn");
782 Exn->setDoesNotThrow();
783 Builder.CreateStore(Exn, getExceptionSlot());
784
785 // Build the selector arguments.
786 llvm::SmallVector<llvm::Value*, 8> EHSelector;
787 EHSelector.push_back(Exn);
John McCall8262b6a2010-07-17 00:43:08 +0000788 EHSelector.push_back(getPersonalityFn(*this, Personality));
John McCallf1549f62010-07-06 01:34:17 +0000789
790 // Accumulate all the handlers in scope.
791 llvm::DenseMap<llvm::Value*, JumpDest> EHHandlers;
792 JumpDest CatchAll;
793 bool HasEHCleanup = false;
794 bool HasEHFilter = false;
795 llvm::SmallVector<llvm::Value*, 8> EHFilters;
796 for (EHScopeStack::iterator I = EHStack.begin(), E = EHStack.end();
797 I != E; ++I) {
798
799 switch (I->getKind()) {
John McCallda65ea82010-07-13 20:32:21 +0000800 case EHScope::LazyCleanup:
801 if (!HasEHCleanup)
802 HasEHCleanup = cast<EHLazyCleanupScope>(*I).isEHCleanup();
803 // We otherwise don't care about cleanups.
804 continue;
805
John McCallf1549f62010-07-06 01:34:17 +0000806 case EHScope::Cleanup:
807 if (!HasEHCleanup)
808 HasEHCleanup = cast<EHCleanupScope>(*I).isEHCleanup();
809 // We otherwise don't care about cleanups.
810 continue;
811
812 case EHScope::Filter: {
813 assert(I.next() == EHStack.end() && "EH filter is not end of EH stack");
814 assert(!CatchAll.Block && "EH filter reached after catch-all");
815
816 // Filter scopes get added to the selector in wierd ways.
817 EHFilterScope &Filter = cast<EHFilterScope>(*I);
818 HasEHFilter = true;
819
820 // Add all the filter values which we aren't already explicitly
821 // catching.
822 for (unsigned I = 0, E = Filter.getNumFilters(); I != E; ++I) {
823 llvm::Value *FV = Filter.getFilter(I);
824 if (!EHHandlers.count(FV))
825 EHFilters.push_back(FV);
826 }
827 goto done;
828 }
829
830 case EHScope::Terminate:
831 // Terminate scopes are basically catch-alls.
832 assert(!CatchAll.Block);
833 CatchAll.Block = getTerminateHandler();
834 CatchAll.ScopeDepth = EHStack.getEnclosingEHCleanup(I);
835 goto done;
836
837 case EHScope::Catch:
838 break;
839 }
840
841 EHCatchScope &Catch = cast<EHCatchScope>(*I);
842 for (unsigned HI = 0, HE = Catch.getNumHandlers(); HI != HE; ++HI) {
843 EHCatchScope::Handler Handler = Catch.getHandler(HI);
844
845 // Catch-all. We should only have one of these per catch.
846 if (!Handler.Type) {
847 assert(!CatchAll.Block);
848 CatchAll.Block = Handler.Block;
849 CatchAll.ScopeDepth = EHStack.getEnclosingEHCleanup(I);
850 continue;
851 }
852
853 // Check whether we already have a handler for this type.
854 JumpDest &Dest = EHHandlers[Handler.Type];
855 if (Dest.Block) continue;
856
857 EHSelector.push_back(Handler.Type);
858 Dest.Block = Handler.Block;
859 Dest.ScopeDepth = EHStack.getEnclosingEHCleanup(I);
860 }
861
862 // Stop if we found a catch-all.
863 if (CatchAll.Block) break;
864 }
865
866 done:
867 unsigned LastToEmitInLoop = EHSelector.size();
868
869 // If we have a catch-all, add null to the selector.
870 if (CatchAll.Block) {
871 EHSelector.push_back(getCatchAllValue(CGF));
872
873 // If we have an EH filter, we need to add those handlers in the
874 // right place in the selector, which is to say, at the end.
875 } else if (HasEHFilter) {
876 // Create a filter expression: an integer constant saying how many
877 // filters there are (+1 to avoid ambiguity with 0 for cleanup),
878 // followed by the filter types. The personality routine only
879 // lands here if the filter doesn't match.
880 EHSelector.push_back(llvm::ConstantInt::get(Builder.getInt32Ty(),
881 EHFilters.size() + 1));
882 EHSelector.append(EHFilters.begin(), EHFilters.end());
883
884 // Also check whether we need a cleanup.
885 if (UseInvokeInlineHack || HasEHCleanup)
886 EHSelector.push_back(UseInvokeInlineHack
887 ? getCatchAllValue(CGF)
888 : getCleanupValue(CGF));
889
890 // Otherwise, signal that we at least have cleanups.
891 } else if (UseInvokeInlineHack || HasEHCleanup) {
892 EHSelector.push_back(UseInvokeInlineHack
893 ? getCatchAllValue(CGF)
894 : getCleanupValue(CGF));
895 } else {
896 assert(LastToEmitInLoop > 2);
897 LastToEmitInLoop--;
898 }
899
900 assert(EHSelector.size() >= 3 && "selector call has only two arguments!");
901
902 // Tell the backend how to generate the landing pad.
903 llvm::CallInst *Selection =
904 Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::eh_selector),
905 EHSelector.begin(), EHSelector.end(), "eh.selector");
906 Selection->setDoesNotThrow();
907
908 // Select the right handler.
909 llvm::Value *llvm_eh_typeid_for =
910 CGM.getIntrinsic(llvm::Intrinsic::eh_typeid_for);
911
912 // The results of llvm_eh_typeid_for aren't reliable --- at least
913 // not locally --- so we basically have to do this as an 'if' chain.
914 // We walk through the first N-1 catch clauses, testing and chaining,
915 // and then fall into the final clause (which is either a cleanup, a
916 // filter (possibly with a cleanup), a catch-all, or another catch).
917 for (unsigned I = 2; I != LastToEmitInLoop; ++I) {
918 llvm::Value *Type = EHSelector[I];
919 JumpDest Dest = EHHandlers[Type];
920 assert(Dest.Block && "no handler entry for value in selector?");
921
922 // Figure out where to branch on a match. As a debug code-size
923 // optimization, if the scope depth matches the innermost cleanup,
924 // we branch directly to the catch handler.
925 llvm::BasicBlock *Match = Dest.Block;
926 bool MatchNeedsCleanup = Dest.ScopeDepth != EHStack.getInnermostEHCleanup();
927 if (MatchNeedsCleanup)
928 Match = createBasicBlock("eh.match");
929
930 llvm::BasicBlock *Next = createBasicBlock("eh.next");
931
932 // Check whether the exception matches.
933 llvm::CallInst *Id
934 = Builder.CreateCall(llvm_eh_typeid_for,
935 Builder.CreateBitCast(Type, CGM.PtrToInt8Ty));
936 Id->setDoesNotThrow();
937 Builder.CreateCondBr(Builder.CreateICmpEQ(Selection, Id),
938 Match, Next);
939
940 // Emit match code if necessary.
941 if (MatchNeedsCleanup) {
942 EmitBlock(Match);
943 EmitBranchThroughEHCleanup(Dest);
944 }
945
946 // Continue to the next match.
947 EmitBlock(Next);
948 }
949
950 // Emit the final case in the selector.
951 // This might be a catch-all....
952 if (CatchAll.Block) {
953 assert(isa<llvm::ConstantPointerNull>(EHSelector.back()));
954 EmitBranchThroughEHCleanup(CatchAll);
955
956 // ...or an EH filter...
957 } else if (HasEHFilter) {
958 llvm::Value *SavedSelection = Selection;
959
960 // First, unwind out to the outermost scope if necessary.
961 if (EHStack.hasEHCleanups()) {
962 // The end here might not dominate the beginning, so we might need to
963 // save the selector if we need it.
964 llvm::AllocaInst *SelectorVar = 0;
965 if (HasEHCleanup) {
966 SelectorVar = CreateTempAlloca(Builder.getInt32Ty(), "selector.var");
967 Builder.CreateStore(Selection, SelectorVar);
968 }
969
970 llvm::BasicBlock *CleanupContBB = createBasicBlock("ehspec.cleanup.cont");
971 EmitBranchThroughEHCleanup(JumpDest(CleanupContBB, EHStack.stable_end()));
972 EmitBlock(CleanupContBB);
973
974 if (HasEHCleanup)
975 SavedSelection = Builder.CreateLoad(SelectorVar, "ehspec.saved-selector");
976 }
977
978 // If there was a cleanup, we'll need to actually check whether we
979 // landed here because the filter triggered.
980 if (UseInvokeInlineHack || HasEHCleanup) {
981 llvm::BasicBlock *RethrowBB = createBasicBlock("cleanup");
982 llvm::BasicBlock *UnexpectedBB = createBasicBlock("ehspec.unexpected");
983
984 llvm::Constant *Zero = llvm::ConstantInt::get(Builder.getInt32Ty(), 0);
985 llvm::Value *FailsFilter =
986 Builder.CreateICmpSLT(SavedSelection, Zero, "ehspec.fails");
987 Builder.CreateCondBr(FailsFilter, UnexpectedBB, RethrowBB);
988
989 // The rethrow block is where we land if this was a cleanup.
990 // TODO: can this be _Unwind_Resume if the InvokeInlineHack is off?
991 EmitBlock(RethrowBB);
992 Builder.CreateCall(getUnwindResumeOrRethrowFn(),
993 Builder.CreateLoad(getExceptionSlot()))
994 ->setDoesNotReturn();
995 Builder.CreateUnreachable();
996
997 EmitBlock(UnexpectedBB);
998 }
999
1000 // Call __cxa_call_unexpected. This doesn't need to be an invoke
1001 // because __cxa_call_unexpected magically filters exceptions
1002 // according to the last landing pad the exception was thrown
1003 // into. Seriously.
1004 Builder.CreateCall(getUnexpectedFn(*this),
1005 Builder.CreateLoad(getExceptionSlot()))
1006 ->setDoesNotReturn();
1007 Builder.CreateUnreachable();
1008
1009 // ...or a normal catch handler...
1010 } else if (!UseInvokeInlineHack && !HasEHCleanup) {
1011 llvm::Value *Type = EHSelector.back();
1012 EmitBranchThroughEHCleanup(EHHandlers[Type]);
1013
1014 // ...or a cleanup.
1015 } else {
1016 // We emit a jump to a notional label at the outermost unwind state.
1017 llvm::BasicBlock *Unwind = createBasicBlock("eh.resume");
1018 JumpDest Dest(Unwind, EHStack.stable_end());
1019 EmitBranchThroughEHCleanup(Dest);
1020
1021 // The unwind block. We have to reload the exception here because
1022 // we might have unwound through arbitrary blocks, so the landing
1023 // pad might not dominate.
1024 EmitBlock(Unwind);
1025
1026 // This can always be a call because we necessarily didn't find
1027 // anything on the EH stack which needs our help.
John McCall8262b6a2010-07-17 00:43:08 +00001028 llvm::Constant *RethrowFn;
1029 if (const char *RethrowName = Personality.getCatchallRethrowFnName())
1030 RethrowFn = getCatchallRethrowFn(CGF, RethrowName);
1031 else
1032 RethrowFn = getUnwindResumeOrRethrowFn();
1033 Builder.CreateCall(RethrowFn, Builder.CreateLoad(getExceptionSlot()))
John McCallf1549f62010-07-06 01:34:17 +00001034 ->setDoesNotReturn();
1035 Builder.CreateUnreachable();
1036 }
1037
1038 // Restore the old IR generation state.
1039 Builder.restoreIP(SavedIP);
1040
1041 return LP;
1042}
1043
John McCall8e3f8612010-07-13 22:12:14 +00001044namespace {
1045 /// A cleanup to call __cxa_end_catch. In many cases, the caught
1046 /// exception type lets us state definitively that the thrown exception
1047 /// type does not have a destructor. In particular:
1048 /// - Catch-alls tell us nothing, so we have to conservatively
1049 /// assume that the thrown exception might have a destructor.
1050 /// - Catches by reference behave according to their base types.
1051 /// - Catches of non-record types will only trigger for exceptions
1052 /// of non-record types, which never have destructors.
1053 /// - Catches of record types can trigger for arbitrary subclasses
1054 /// of the caught type, so we have to assume the actual thrown
1055 /// exception type might have a throwing destructor, even if the
1056 /// caught type's destructor is trivial or nothrow.
1057 struct CallEndCatch : EHScopeStack::LazyCleanup {
1058 CallEndCatch(bool MightThrow) : MightThrow(MightThrow) {}
1059 bool MightThrow;
1060
1061 void Emit(CodeGenFunction &CGF, bool IsForEH) {
1062 if (!MightThrow) {
1063 CGF.Builder.CreateCall(getEndCatchFn(CGF))->setDoesNotThrow();
1064 return;
1065 }
1066
1067 CGF.EmitCallOrInvoke(getEndCatchFn(CGF), 0, 0);
1068 }
1069 };
1070}
1071
John McCallf1549f62010-07-06 01:34:17 +00001072/// Emits a call to __cxa_begin_catch and enters a cleanup to call
1073/// __cxa_end_catch.
John McCall8e3f8612010-07-13 22:12:14 +00001074///
1075/// \param EndMightThrow - true if __cxa_end_catch might throw
1076static llvm::Value *CallBeginCatch(CodeGenFunction &CGF,
1077 llvm::Value *Exn,
1078 bool EndMightThrow) {
John McCallf1549f62010-07-06 01:34:17 +00001079 llvm::CallInst *Call = CGF.Builder.CreateCall(getBeginCatchFn(CGF), Exn);
1080 Call->setDoesNotThrow();
1081
John McCall8e3f8612010-07-13 22:12:14 +00001082 CGF.EHStack.pushLazyCleanup<CallEndCatch>(NormalAndEHCleanup, EndMightThrow);
John McCallf1549f62010-07-06 01:34:17 +00001083
1084 return Call;
1085}
1086
1087/// A "special initializer" callback for initializing a catch
1088/// parameter during catch initialization.
1089static void InitCatchParam(CodeGenFunction &CGF,
1090 const VarDecl &CatchParam,
1091 llvm::Value *ParamAddr) {
1092 // Load the exception from where the landing pad saved it.
1093 llvm::Value *Exn = CGF.Builder.CreateLoad(CGF.getExceptionSlot(), "exn");
1094
1095 CanQualType CatchType =
1096 CGF.CGM.getContext().getCanonicalType(CatchParam.getType());
1097 const llvm::Type *LLVMCatchTy = CGF.ConvertTypeForMem(CatchType);
1098
1099 // If we're catching by reference, we can just cast the object
1100 // pointer to the appropriate pointer.
1101 if (isa<ReferenceType>(CatchType)) {
John McCall8e3f8612010-07-13 22:12:14 +00001102 bool EndCatchMightThrow = cast<ReferenceType>(CatchType)->getPointeeType()
1103 ->isRecordType();
1104
John McCallf1549f62010-07-06 01:34:17 +00001105 // __cxa_begin_catch returns the adjusted object pointer.
John McCall8e3f8612010-07-13 22:12:14 +00001106 llvm::Value *AdjustedExn = CallBeginCatch(CGF, Exn, EndCatchMightThrow);
John McCallf1549f62010-07-06 01:34:17 +00001107 llvm::Value *ExnCast =
1108 CGF.Builder.CreateBitCast(AdjustedExn, LLVMCatchTy, "exn.byref");
1109 CGF.Builder.CreateStore(ExnCast, ParamAddr);
1110 return;
1111 }
1112
1113 // Non-aggregates (plus complexes).
1114 bool IsComplex = false;
1115 if (!CGF.hasAggregateLLVMType(CatchType) ||
1116 (IsComplex = CatchType->isAnyComplexType())) {
John McCall8e3f8612010-07-13 22:12:14 +00001117 llvm::Value *AdjustedExn = CallBeginCatch(CGF, Exn, false);
John McCallf1549f62010-07-06 01:34:17 +00001118
1119 // If the catch type is a pointer type, __cxa_begin_catch returns
1120 // the pointer by value.
1121 if (CatchType->hasPointerRepresentation()) {
1122 llvm::Value *CastExn =
1123 CGF.Builder.CreateBitCast(AdjustedExn, LLVMCatchTy, "exn.casted");
1124 CGF.Builder.CreateStore(CastExn, ParamAddr);
1125 return;
1126 }
1127
1128 // Otherwise, it returns a pointer into the exception object.
1129
1130 const llvm::Type *PtrTy = LLVMCatchTy->getPointerTo(0); // addrspace 0 ok
1131 llvm::Value *Cast = CGF.Builder.CreateBitCast(AdjustedExn, PtrTy);
1132
1133 if (IsComplex) {
1134 CGF.StoreComplexToAddr(CGF.LoadComplexFromAddr(Cast, /*volatile*/ false),
1135 ParamAddr, /*volatile*/ false);
1136 } else {
1137 llvm::Value *ExnLoad = CGF.Builder.CreateLoad(Cast, "exn.scalar");
1138 CGF.EmitStoreOfScalar(ExnLoad, ParamAddr, /*volatile*/ false, CatchType);
1139 }
1140 return;
1141 }
1142
1143 // FIXME: this *really* needs to be done via a proper, Sema-emitted
1144 // initializer expression.
1145
1146 CXXRecordDecl *RD = CatchType.getTypePtr()->getAsCXXRecordDecl();
1147 assert(RD && "aggregate catch type was not a record!");
1148
1149 const llvm::Type *PtrTy = LLVMCatchTy->getPointerTo(0); // addrspace 0 ok
1150
1151 if (RD->hasTrivialCopyConstructor()) {
John McCall8e3f8612010-07-13 22:12:14 +00001152 llvm::Value *AdjustedExn = CallBeginCatch(CGF, Exn, true);
John McCallf1549f62010-07-06 01:34:17 +00001153 llvm::Value *Cast = CGF.Builder.CreateBitCast(AdjustedExn, PtrTy);
1154 CGF.EmitAggregateCopy(ParamAddr, Cast, CatchType);
1155 return;
1156 }
1157
1158 // We have to call __cxa_get_exception_ptr to get the adjusted
1159 // pointer before copying.
1160 llvm::CallInst *AdjustedExn =
1161 CGF.Builder.CreateCall(getGetExceptionPtrFn(CGF), Exn);
1162 AdjustedExn->setDoesNotThrow();
1163 llvm::Value *Cast = CGF.Builder.CreateBitCast(AdjustedExn, PtrTy);
1164
1165 CXXConstructorDecl *CD = RD->getCopyConstructor(CGF.getContext(), 0);
1166 assert(CD && "record has no copy constructor!");
1167 llvm::Value *CopyCtor = CGF.CGM.GetAddrOfCXXConstructor(CD, Ctor_Complete);
1168
1169 CallArgList CallArgs;
1170 CallArgs.push_back(std::make_pair(RValue::get(ParamAddr),
1171 CD->getThisType(CGF.getContext())));
1172 CallArgs.push_back(std::make_pair(RValue::get(Cast),
1173 CD->getParamDecl(0)->getType()));
1174
1175 const FunctionProtoType *FPT
1176 = CD->getType()->getAs<FunctionProtoType>();
1177
1178 // Call the copy ctor in a terminate scope.
1179 CGF.EHStack.pushTerminate();
1180 CGF.EmitCall(CGF.CGM.getTypes().getFunctionInfo(CallArgs, FPT),
1181 CopyCtor, ReturnValueSlot(), CallArgs, CD);
1182 CGF.EHStack.popTerminate();
1183
1184 // Finally we can call __cxa_begin_catch.
John McCall8e3f8612010-07-13 22:12:14 +00001185 CallBeginCatch(CGF, Exn, true);
John McCallf1549f62010-07-06 01:34:17 +00001186}
1187
1188/// Begins a catch statement by initializing the catch variable and
1189/// calling __cxa_begin_catch.
1190static void BeginCatch(CodeGenFunction &CGF,
1191 const CXXCatchStmt *S) {
1192 // We have to be very careful with the ordering of cleanups here:
1193 // C++ [except.throw]p4:
1194 // The destruction [of the exception temporary] occurs
1195 // immediately after the destruction of the object declared in
1196 // the exception-declaration in the handler.
1197 //
1198 // So the precise ordering is:
1199 // 1. Construct catch variable.
1200 // 2. __cxa_begin_catch
1201 // 3. Enter __cxa_end_catch cleanup
1202 // 4. Enter dtor cleanup
1203 //
1204 // We do this by initializing the exception variable with a
1205 // "special initializer", InitCatchParam. Delegation sequence:
1206 // - ExitCXXTryStmt opens a RunCleanupsScope
1207 // - EmitLocalBlockVarDecl creates the variable and debug info
1208 // - InitCatchParam initializes the variable from the exception
1209 // - CallBeginCatch calls __cxa_begin_catch
1210 // - CallBeginCatch enters the __cxa_end_catch cleanup
1211 // - EmitLocalBlockVarDecl enters the variable destructor cleanup
1212 // - EmitCXXTryStmt emits the code for the catch body
1213 // - EmitCXXTryStmt close the RunCleanupsScope
1214
1215 VarDecl *CatchParam = S->getExceptionDecl();
1216 if (!CatchParam) {
1217 llvm::Value *Exn = CGF.Builder.CreateLoad(CGF.getExceptionSlot(), "exn");
John McCall8e3f8612010-07-13 22:12:14 +00001218 CallBeginCatch(CGF, Exn, true);
John McCallf1549f62010-07-06 01:34:17 +00001219 return;
1220 }
1221
1222 // Emit the local.
1223 CGF.EmitLocalBlockVarDecl(*CatchParam, &InitCatchParam);
John McCall9fc6a772010-02-19 09:25:03 +00001224}
1225
John McCallfcd5c0c2010-07-13 22:24:23 +00001226namespace {
1227 struct CallRethrow : EHScopeStack::LazyCleanup {
1228 void Emit(CodeGenFunction &CGF, bool IsForEH) {
1229 CGF.EmitCallOrInvoke(getReThrowFn(CGF), 0, 0);
1230 }
1231 };
1232}
1233
John McCall59a70002010-07-07 06:56:46 +00001234void CodeGenFunction::ExitCXXTryStmt(const CXXTryStmt &S, bool IsFnTryBlock) {
John McCallf1549f62010-07-06 01:34:17 +00001235 unsigned NumHandlers = S.getNumHandlers();
1236 EHCatchScope &CatchScope = cast<EHCatchScope>(*EHStack.begin());
1237 assert(CatchScope.getNumHandlers() == NumHandlers);
Mike Stump2bf701e2009-11-20 23:44:51 +00001238
John McCallf1549f62010-07-06 01:34:17 +00001239 // Copy the handler blocks off before we pop the EH stack. Emitting
1240 // the handlers might scribble on this memory.
1241 llvm::SmallVector<EHCatchScope::Handler, 8> Handlers(NumHandlers);
1242 memcpy(Handlers.data(), CatchScope.begin(),
1243 NumHandlers * sizeof(EHCatchScope::Handler));
1244 EHStack.popCatch();
Mike Stump2bf701e2009-11-20 23:44:51 +00001245
John McCallf1549f62010-07-06 01:34:17 +00001246 // The fall-through block.
1247 llvm::BasicBlock *ContBB = createBasicBlock("try.cont");
Mike Stump2bf701e2009-11-20 23:44:51 +00001248
John McCallf1549f62010-07-06 01:34:17 +00001249 // We just emitted the body of the try; jump to the continue block.
1250 if (HaveInsertPoint())
1251 Builder.CreateBr(ContBB);
Mike Stump639787c2009-12-02 19:53:57 +00001252
John McCall59a70002010-07-07 06:56:46 +00001253 // Determine if we need an implicit rethrow for all these catch handlers.
1254 bool ImplicitRethrow = false;
1255 if (IsFnTryBlock)
1256 ImplicitRethrow = isa<CXXDestructorDecl>(CurCodeDecl) ||
1257 isa<CXXConstructorDecl>(CurCodeDecl);
1258
John McCallf1549f62010-07-06 01:34:17 +00001259 for (unsigned I = 0; I != NumHandlers; ++I) {
1260 llvm::BasicBlock *CatchBlock = Handlers[I].Block;
1261 EmitBlock(CatchBlock);
Mike Stump8755ec32009-12-10 00:06:18 +00001262
John McCallf1549f62010-07-06 01:34:17 +00001263 // Catch the exception if this isn't a catch-all.
1264 const CXXCatchStmt *C = S.getHandler(I);
Mike Stump2bf701e2009-11-20 23:44:51 +00001265
John McCallf1549f62010-07-06 01:34:17 +00001266 // Enter a cleanup scope, including the catch variable and the
1267 // end-catch.
1268 RunCleanupsScope CatchScope(*this);
Mike Stump2bf701e2009-11-20 23:44:51 +00001269
John McCallf1549f62010-07-06 01:34:17 +00001270 // Initialize the catch variable and set up the cleanups.
1271 BeginCatch(*this, C);
1272
John McCall59a70002010-07-07 06:56:46 +00001273 // If there's an implicit rethrow, push a normal "cleanup" to call
John McCallfcd5c0c2010-07-13 22:24:23 +00001274 // _cxa_rethrow. This needs to happen before __cxa_end_catch is
1275 // called, and so it is pushed after BeginCatch.
1276 if (ImplicitRethrow)
1277 EHStack.pushLazyCleanup<CallRethrow>(NormalCleanup);
John McCall59a70002010-07-07 06:56:46 +00001278
John McCallf1549f62010-07-06 01:34:17 +00001279 // Perform the body of the catch.
1280 EmitStmt(C->getHandlerBlock());
1281
1282 // Fall out through the catch cleanups.
1283 CatchScope.ForceCleanup();
1284
1285 // Branch out of the try.
1286 if (HaveInsertPoint())
1287 Builder.CreateBr(ContBB);
Mike Stump2bf701e2009-11-20 23:44:51 +00001288 }
1289
John McCallf1549f62010-07-06 01:34:17 +00001290 EmitBlock(ContBB);
Mike Stump2bf701e2009-11-20 23:44:51 +00001291}
Mike Stumpd88ea562009-12-09 03:35:49 +00001292
John McCallf1549f62010-07-06 01:34:17 +00001293/// Enters a finally block for an implementation using zero-cost
1294/// exceptions. This is mostly general, but hard-codes some
1295/// language/ABI-specific behavior in the catch-all sections.
1296CodeGenFunction::FinallyInfo
1297CodeGenFunction::EnterFinallyBlock(const Stmt *Body,
1298 llvm::Constant *BeginCatchFn,
1299 llvm::Constant *EndCatchFn,
1300 llvm::Constant *RethrowFn) {
1301 assert((BeginCatchFn != 0) == (EndCatchFn != 0) &&
1302 "begin/end catch functions not paired");
1303 assert(RethrowFn && "rethrow function is required");
Mike Stumpd88ea562009-12-09 03:35:49 +00001304
John McCallf1549f62010-07-06 01:34:17 +00001305 // The rethrow function has one of the following two types:
1306 // void (*)()
1307 // void (*)(void*)
1308 // In the latter case we need to pass it the exception object.
1309 // But we can't use the exception slot because the @finally might
1310 // have a landing pad (which would overwrite the exception slot).
1311 const llvm::FunctionType *RethrowFnTy =
1312 cast<llvm::FunctionType>(
1313 cast<llvm::PointerType>(RethrowFn->getType())
1314 ->getElementType());
1315 llvm::Value *SavedExnVar = 0;
1316 if (RethrowFnTy->getNumParams())
1317 SavedExnVar = CreateTempAlloca(Builder.getInt8PtrTy(), "finally.exn");
Mike Stumpd88ea562009-12-09 03:35:49 +00001318
John McCallf1549f62010-07-06 01:34:17 +00001319 // A finally block is a statement which must be executed on any edge
1320 // out of a given scope. Unlike a cleanup, the finally block may
1321 // contain arbitrary control flow leading out of itself. In
1322 // addition, finally blocks should always be executed, even if there
1323 // are no catch handlers higher on the stack. Therefore, we
1324 // surround the protected scope with a combination of a normal
1325 // cleanup (to catch attempts to break out of the block via normal
1326 // control flow) and an EH catch-all (semantically "outside" any try
1327 // statement to which the finally block might have been attached).
1328 // The finally block itself is generated in the context of a cleanup
1329 // which conditionally leaves the catch-all.
John McCall3d3ec1c2010-04-21 10:05:39 +00001330
John McCallf1549f62010-07-06 01:34:17 +00001331 FinallyInfo Info;
John McCall3d3ec1c2010-04-21 10:05:39 +00001332
John McCallf1549f62010-07-06 01:34:17 +00001333 // Jump destination for performing the finally block on an exception
1334 // edge. We'll never actually reach this block, so unreachable is
1335 // fine.
1336 JumpDest RethrowDest = getJumpDestInCurrentScope(getUnreachableBlock());
John McCall3d3ec1c2010-04-21 10:05:39 +00001337
John McCallf1549f62010-07-06 01:34:17 +00001338 // Whether the finally block is being executed for EH purposes.
1339 llvm::AllocaInst *ForEHVar = CreateTempAlloca(CGF.Builder.getInt1Ty(),
1340 "finally.for-eh");
1341 InitTempAlloca(ForEHVar, llvm::ConstantInt::getFalse(getLLVMContext()));
Mike Stumpd88ea562009-12-09 03:35:49 +00001342
John McCallf1549f62010-07-06 01:34:17 +00001343 // Enter a normal cleanup which will perform the @finally block.
1344 {
John McCallda65ea82010-07-13 20:32:21 +00001345 CodeGenFunction::CleanupBlock Cleanup(*this, NormalCleanup);
Mike Stumpd88ea562009-12-09 03:35:49 +00001346
John McCallf1549f62010-07-06 01:34:17 +00001347 // Enter a cleanup to call the end-catch function if one was provided.
1348 if (EndCatchFn) {
John McCallda65ea82010-07-13 20:32:21 +00001349 CodeGenFunction::CleanupBlock FinallyExitCleanup(CGF, NormalAndEHCleanup);
John McCallf1549f62010-07-06 01:34:17 +00001350
1351 llvm::BasicBlock *EndCatchBB = createBasicBlock("finally.endcatch");
1352 llvm::BasicBlock *CleanupContBB = createBasicBlock("finally.cleanup.cont");
1353
1354 llvm::Value *ShouldEndCatch =
1355 Builder.CreateLoad(ForEHVar, "finally.endcatch");
1356 Builder.CreateCondBr(ShouldEndCatch, EndCatchBB, CleanupContBB);
1357 EmitBlock(EndCatchBB);
John McCall8e3f8612010-07-13 22:12:14 +00001358 EmitCallOrInvoke(EndCatchFn, 0, 0); // catch-all, so might throw
John McCallf1549f62010-07-06 01:34:17 +00001359 EmitBlock(CleanupContBB);
1360 }
1361
1362 // Emit the finally block.
1363 EmitStmt(Body);
1364
1365 // If the end of the finally is reachable, check whether this was
1366 // for EH. If so, rethrow.
1367 if (HaveInsertPoint()) {
1368 llvm::BasicBlock *RethrowBB = createBasicBlock("finally.rethrow");
1369 llvm::BasicBlock *ContBB = createBasicBlock("finally.cont");
1370
1371 llvm::Value *ShouldRethrow =
1372 Builder.CreateLoad(ForEHVar, "finally.shouldthrow");
1373 Builder.CreateCondBr(ShouldRethrow, RethrowBB, ContBB);
1374
1375 EmitBlock(RethrowBB);
1376 if (SavedExnVar) {
1377 llvm::Value *Args[] = { Builder.CreateLoad(SavedExnVar) };
1378 EmitCallOrInvoke(RethrowFn, Args, Args+1);
1379 } else {
1380 EmitCallOrInvoke(RethrowFn, 0, 0);
1381 }
1382 Builder.CreateUnreachable();
1383
1384 EmitBlock(ContBB);
1385 }
1386
1387 // Leave the end-catch cleanup. As an optimization, pretend that
1388 // the fallthrough path was inaccessible; we've dynamically proven
1389 // that we're not in the EH case along that path.
1390 if (EndCatchFn) {
1391 CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
1392 PopCleanupBlock();
1393 Builder.restoreIP(SavedIP);
1394 }
1395
1396 // Now make sure we actually have an insertion point or the
1397 // cleanup gods will hate us.
1398 EnsureInsertPoint();
1399 }
1400
1401 // Enter a catch-all scope.
1402 llvm::BasicBlock *CatchAllBB = createBasicBlock("finally.catchall");
1403 CGBuilderTy::InsertPoint SavedIP = Builder.saveIP();
1404 Builder.SetInsertPoint(CatchAllBB);
1405
1406 // If there's a begin-catch function, call it.
1407 if (BeginCatchFn) {
1408 Builder.CreateCall(BeginCatchFn, Builder.CreateLoad(getExceptionSlot()))
1409 ->setDoesNotThrow();
1410 }
1411
1412 // If we need to remember the exception pointer to rethrow later, do so.
1413 if (SavedExnVar) {
1414 llvm::Value *SavedExn = Builder.CreateLoad(getExceptionSlot());
1415 Builder.CreateStore(SavedExn, SavedExnVar);
1416 }
1417
1418 // Tell the finally block that we're in EH.
1419 Builder.CreateStore(llvm::ConstantInt::getTrue(getLLVMContext()), ForEHVar);
1420
1421 // Thread a jump through the finally cleanup.
1422 EmitBranchThroughCleanup(RethrowDest);
1423
1424 Builder.restoreIP(SavedIP);
1425
1426 EHCatchScope *CatchScope = EHStack.pushCatch(1);
1427 CatchScope->setCatchAllHandler(0, CatchAllBB);
1428
1429 return Info;
1430}
1431
1432void CodeGenFunction::ExitFinallyBlock(FinallyInfo &Info) {
1433 // Leave the finally catch-all.
1434 EHCatchScope &Catch = cast<EHCatchScope>(*EHStack.begin());
1435 llvm::BasicBlock *CatchAllBB = Catch.getHandler(0).Block;
1436 EHStack.popCatch();
1437
1438 // And leave the normal cleanup.
1439 PopCleanupBlock();
1440
1441 CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
1442 EmitBlock(CatchAllBB, true);
1443
1444 Builder.restoreIP(SavedIP);
1445}
1446
1447llvm::BasicBlock *CodeGenFunction::getTerminateLandingPad() {
1448 if (TerminateLandingPad)
1449 return TerminateLandingPad;
1450
1451 CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
1452
1453 // This will get inserted at the end of the function.
1454 TerminateLandingPad = createBasicBlock("terminate.lpad");
1455 Builder.SetInsertPoint(TerminateLandingPad);
1456
1457 // Tell the backend that this is a landing pad.
1458 llvm::CallInst *Exn =
1459 Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::eh_exception), "exn");
1460 Exn->setDoesNotThrow();
John McCall8262b6a2010-07-17 00:43:08 +00001461
1462 const EHPersonality &Personality = EHPersonality::get(CGM.getLangOptions());
John McCallf1549f62010-07-06 01:34:17 +00001463
1464 // Tell the backend what the exception table should be:
1465 // nothing but a catch-all.
John McCall8262b6a2010-07-17 00:43:08 +00001466 llvm::Value *Args[3] = { Exn, getPersonalityFn(*this, Personality),
John McCallf1549f62010-07-06 01:34:17 +00001467 getCatchAllValue(*this) };
1468 Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::eh_selector),
1469 Args, Args+3, "eh.selector")
1470 ->setDoesNotThrow();
1471
1472 llvm::CallInst *TerminateCall = Builder.CreateCall(getTerminateFn(*this));
1473 TerminateCall->setDoesNotReturn();
1474 TerminateCall->setDoesNotThrow();
Mike Stumpd88ea562009-12-09 03:35:49 +00001475 CGF.Builder.CreateUnreachable();
1476
John McCallf1549f62010-07-06 01:34:17 +00001477 // Restore the saved insertion state.
1478 Builder.restoreIP(SavedIP);
John McCall891f80e2010-04-30 00:06:43 +00001479
John McCallf1549f62010-07-06 01:34:17 +00001480 return TerminateLandingPad;
Mike Stumpd88ea562009-12-09 03:35:49 +00001481}
Mike Stump9b39c512009-12-09 22:59:31 +00001482
1483llvm::BasicBlock *CodeGenFunction::getTerminateHandler() {
Mike Stump182f3832009-12-10 00:02:42 +00001484 if (TerminateHandler)
1485 return TerminateHandler;
1486
John McCallf1549f62010-07-06 01:34:17 +00001487 CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
Mike Stump76958092009-12-09 23:31:35 +00001488
John McCallf1549f62010-07-06 01:34:17 +00001489 // Set up the terminate handler. This block is inserted at the very
1490 // end of the function by FinishFunction.
Mike Stump182f3832009-12-10 00:02:42 +00001491 TerminateHandler = createBasicBlock("terminate.handler");
John McCallf1549f62010-07-06 01:34:17 +00001492 Builder.SetInsertPoint(TerminateHandler);
1493 llvm::CallInst *TerminateCall = Builder.CreateCall(getTerminateFn(*this));
Mike Stump9b39c512009-12-09 22:59:31 +00001494 TerminateCall->setDoesNotReturn();
1495 TerminateCall->setDoesNotThrow();
1496 Builder.CreateUnreachable();
1497
John McCall3d3ec1c2010-04-21 10:05:39 +00001498 // Restore the saved insertion state.
John McCallf1549f62010-07-06 01:34:17 +00001499 Builder.restoreIP(SavedIP);
Mike Stump76958092009-12-09 23:31:35 +00001500
Mike Stump9b39c512009-12-09 22:59:31 +00001501 return TerminateHandler;
1502}
John McCallf1549f62010-07-06 01:34:17 +00001503
1504CodeGenFunction::CleanupBlock::CleanupBlock(CodeGenFunction &CGF,
1505 CleanupKind Kind)
1506 : CGF(CGF), SavedIP(CGF.Builder.saveIP()), NormalCleanupExitBB(0) {
1507 llvm::BasicBlock *EntryBB = CGF.createBasicBlock("cleanup");
1508 CGF.Builder.SetInsertPoint(EntryBB);
1509
1510 switch (Kind) {
1511 case NormalAndEHCleanup:
1512 NormalCleanupEntryBB = EHCleanupEntryBB = EntryBB;
1513 break;
1514
1515 case NormalCleanup:
1516 NormalCleanupEntryBB = EntryBB;
1517 EHCleanupEntryBB = 0;
1518 break;
1519
1520 case EHCleanup:
1521 NormalCleanupEntryBB = 0;
1522 EHCleanupEntryBB = EntryBB;
1523 CGF.EHStack.pushTerminate();
1524 break;
1525 }
1526}
1527
1528void CodeGenFunction::CleanupBlock::beginEHCleanup() {
1529 assert(EHCleanupEntryBB == 0 && "already started an EH cleanup");
1530 NormalCleanupExitBB = CGF.Builder.GetInsertBlock();
1531 assert(NormalCleanupExitBB && "end of normal cleanup is unreachable");
1532
1533 EHCleanupEntryBB = CGF.createBasicBlock("eh.cleanup");
1534 CGF.Builder.SetInsertPoint(EHCleanupEntryBB);
1535 CGF.EHStack.pushTerminate();
1536}
1537
1538CodeGenFunction::CleanupBlock::~CleanupBlock() {
1539 llvm::BasicBlock *EHCleanupExitBB = 0;
1540
1541 // If we're currently writing the EH cleanup...
1542 if (EHCleanupEntryBB) {
1543 // Set the EH cleanup exit block.
1544 EHCleanupExitBB = CGF.Builder.GetInsertBlock();
1545 assert(EHCleanupExitBB && "end of EH cleanup is unreachable");
1546
1547 // If we're actually writing both at once, set the normal exit, too.
1548 if (EHCleanupEntryBB == NormalCleanupEntryBB)
1549 NormalCleanupExitBB = EHCleanupExitBB;
1550
1551 // Otherwise, we must have pushed a terminate handler.
1552 else
1553 CGF.EHStack.popTerminate();
1554
1555 // Otherwise, just set the normal cleanup exit block.
1556 } else {
1557 NormalCleanupExitBB = CGF.Builder.GetInsertBlock();
1558 assert(NormalCleanupExitBB && "end of normal cleanup is unreachable");
1559 }
1560
1561 CGF.EHStack.pushCleanup(NormalCleanupEntryBB, NormalCleanupExitBB,
1562 EHCleanupEntryBB, EHCleanupExitBB);
1563
1564 CGF.Builder.restoreIP(SavedIP);
1565}
1566
John McCall3e29f962010-07-13 23:19:49 +00001567EHScopeStack::LazyCleanup::~LazyCleanup() {
1568 llvm_unreachable("LazyCleanup is indestructable");
1569}