1 //===--- CGException.cpp - Emit LLVM Code for C++ exceptions ----*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This contains code dealing with C++ exception related code generation.
12 //===----------------------------------------------------------------------===//
14 #include "CodeGenFunction.h"
16 #include "CGCleanup.h"
17 #include "CGObjCRuntime.h"
18 #include "ConstantEmitter.h"
19 #include "TargetInfo.h"
20 #include "clang/AST/Mangle.h"
21 #include "clang/AST/StmtCXX.h"
22 #include "clang/AST/StmtObjC.h"
23 #include "clang/AST/StmtVisitor.h"
24 #include "clang/Basic/TargetBuiltins.h"
25 #include "llvm/IR/CallSite.h"
26 #include "llvm/IR/Intrinsics.h"
27 #include "llvm/IR/IntrinsicInst.h"
28 #include "llvm/Support/SaveAndRestore.h"
30 using namespace clang;
31 using namespace CodeGen;
33 static llvm::Constant *getFreeExceptionFn(CodeGenModule &CGM) {
34 // void __cxa_free_exception(void *thrown_exception);
36 llvm::FunctionType *FTy =
37 llvm::FunctionType::get(CGM.VoidTy, CGM.Int8PtrTy, /*IsVarArgs=*/false);
39 return CGM.CreateRuntimeFunction(FTy, "__cxa_free_exception");
42 static llvm::Constant *getUnexpectedFn(CodeGenModule &CGM) {
43 // void __cxa_call_unexpected(void *thrown_exception);
45 llvm::FunctionType *FTy =
46 llvm::FunctionType::get(CGM.VoidTy, CGM.Int8PtrTy, /*IsVarArgs=*/false);
48 return CGM.CreateRuntimeFunction(FTy, "__cxa_call_unexpected");
51 llvm::Constant *CodeGenModule::getTerminateFn() {
52 // void __terminate();
54 llvm::FunctionType *FTy =
55 llvm::FunctionType::get(VoidTy, /*IsVarArgs=*/false);
59 // In C++, use std::terminate().
60 if (getLangOpts().CPlusPlus &&
61 getTarget().getCXXABI().isItaniumFamily()) {
62 name = "_ZSt9terminatev";
63 } else if (getLangOpts().CPlusPlus &&
64 getTarget().getCXXABI().isMicrosoft()) {
65 if (getLangOpts().isCompatibleWithMSVC(LangOptions::MSVC2015))
66 name = "__std_terminate";
68 name = "\01?terminate@@YAXXZ";
69 } else if (getLangOpts().ObjC1 &&
70 getLangOpts().ObjCRuntime.hasTerminate())
71 name = "objc_terminate";
74 return CreateRuntimeFunction(FTy, name);
77 static llvm::Constant *getCatchallRethrowFn(CodeGenModule &CGM,
79 llvm::FunctionType *FTy =
80 llvm::FunctionType::get(CGM.VoidTy, CGM.Int8PtrTy, /*IsVarArgs=*/false);
82 return CGM.CreateRuntimeFunction(FTy, Name);
85 const EHPersonality EHPersonality::GNU_C = { "__gcc_personality_v0", nullptr };
87 EHPersonality::GNU_C_SJLJ = { "__gcc_personality_sj0", nullptr };
89 EHPersonality::GNU_C_SEH = { "__gcc_personality_seh0", nullptr };
91 EHPersonality::NeXT_ObjC = { "__objc_personality_v0", nullptr };
93 EHPersonality::GNU_CPlusPlus = { "__gxx_personality_v0", nullptr };
95 EHPersonality::GNU_CPlusPlus_SJLJ = { "__gxx_personality_sj0", nullptr };
97 EHPersonality::GNU_CPlusPlus_SEH = { "__gxx_personality_seh0", nullptr };
99 EHPersonality::GNU_ObjC = {"__gnu_objc_personality_v0", "objc_exception_throw"};
101 EHPersonality::GNU_ObjC_SJLJ = {"__gnu_objc_personality_sj0", "objc_exception_throw"};
103 EHPersonality::GNU_ObjC_SEH = {"__gnu_objc_personality_seh0", "objc_exception_throw"};
105 EHPersonality::GNU_ObjCXX = { "__gnustep_objcxx_personality_v0", nullptr };
107 EHPersonality::GNUstep_ObjC = { "__gnustep_objc_personality_v0", nullptr };
109 EHPersonality::MSVC_except_handler = { "_except_handler3", nullptr };
111 EHPersonality::MSVC_C_specific_handler = { "__C_specific_handler", nullptr };
113 EHPersonality::MSVC_CxxFrameHandler3 = { "__CxxFrameHandler3", nullptr };
115 static const EHPersonality &getCPersonality(const llvm::Triple &T,
116 const LangOptions &L) {
117 if (L.SjLjExceptions)
118 return EHPersonality::GNU_C_SJLJ;
120 return EHPersonality::GNU_C_SEH;
121 return EHPersonality::GNU_C;
124 static const EHPersonality &getObjCPersonality(const llvm::Triple &T,
125 const LangOptions &L) {
126 switch (L.ObjCRuntime.getKind()) {
127 case ObjCRuntime::FragileMacOSX:
128 return getCPersonality(T, L);
129 case ObjCRuntime::MacOSX:
130 case ObjCRuntime::iOS:
131 case ObjCRuntime::WatchOS:
132 return EHPersonality::NeXT_ObjC;
133 case ObjCRuntime::GNUstep:
134 if (L.ObjCRuntime.getVersion() >= VersionTuple(1, 7))
135 return EHPersonality::GNUstep_ObjC;
137 case ObjCRuntime::GCC:
138 case ObjCRuntime::ObjFW:
139 if (L.SjLjExceptions)
140 return EHPersonality::GNU_ObjC_SJLJ;
142 return EHPersonality::GNU_ObjC_SEH;
143 return EHPersonality::GNU_ObjC;
145 llvm_unreachable("bad runtime kind");
148 static const EHPersonality &getCXXPersonality(const llvm::Triple &T,
149 const LangOptions &L) {
150 if (L.SjLjExceptions)
151 return EHPersonality::GNU_CPlusPlus_SJLJ;
153 return EHPersonality::GNU_CPlusPlus_SEH;
154 return EHPersonality::GNU_CPlusPlus;
157 /// Determines the personality function to use when both C++
158 /// and Objective-C exceptions are being caught.
159 static const EHPersonality &getObjCXXPersonality(const llvm::Triple &T,
160 const LangOptions &L) {
161 switch (L.ObjCRuntime.getKind()) {
162 // In the fragile ABI, just use C++ exception handling and hope
163 // they're not doing crazy exception mixing.
164 case ObjCRuntime::FragileMacOSX:
165 return getCXXPersonality(T, L);
167 // The ObjC personality defers to the C++ personality for non-ObjC
168 // handlers. Unlike the C++ case, we use the same personality
169 // function on targets using (backend-driven) SJLJ EH.
170 case ObjCRuntime::MacOSX:
171 case ObjCRuntime::iOS:
172 case ObjCRuntime::WatchOS:
173 return getObjCPersonality(T, L);
175 case ObjCRuntime::GNUstep:
176 return EHPersonality::GNU_ObjCXX;
178 // The GCC runtime's personality function inherently doesn't support
179 // mixed EH. Use the ObjC personality just to avoid returning null.
180 case ObjCRuntime::GCC:
181 case ObjCRuntime::ObjFW:
182 return getObjCPersonality(T, L);
184 llvm_unreachable("bad runtime kind");
187 static const EHPersonality &getSEHPersonalityMSVC(const llvm::Triple &T) {
188 if (T.getArch() == llvm::Triple::x86)
189 return EHPersonality::MSVC_except_handler;
190 return EHPersonality::MSVC_C_specific_handler;
193 const EHPersonality &EHPersonality::get(CodeGenModule &CGM,
194 const FunctionDecl *FD) {
195 const llvm::Triple &T = CGM.getTarget().getTriple();
196 const LangOptions &L = CGM.getLangOpts();
198 // Functions using SEH get an SEH personality.
199 if (FD && FD->usesSEHTry())
200 return getSEHPersonalityMSVC(T);
202 // Try to pick a personality function that is compatible with MSVC if we're
203 // not compiling Obj-C. Obj-C users better have an Obj-C runtime that supports
204 // the GCC-style personality function.
205 if (T.isWindowsMSVCEnvironment() && !L.ObjC1) {
206 if (L.SjLjExceptions)
207 return EHPersonality::GNU_CPlusPlus_SJLJ;
208 if (L.DWARFExceptions)
209 return EHPersonality::GNU_CPlusPlus;
210 return EHPersonality::MSVC_CxxFrameHandler3;
213 if (L.CPlusPlus && L.ObjC1)
214 return getObjCXXPersonality(T, L);
215 else if (L.CPlusPlus)
216 return getCXXPersonality(T, L);
218 return getObjCPersonality(T, L);
220 return getCPersonality(T, L);
223 const EHPersonality &EHPersonality::get(CodeGenFunction &CGF) {
224 const auto *FD = CGF.CurCodeDecl;
225 // For outlined finallys and filters, use the SEH personality in case they
226 // contain more SEH. This mostly only affects finallys. Filters could
227 // hypothetically use gnu statement expressions to sneak in nested SEH.
228 FD = FD ? FD : CGF.CurSEHParent;
229 return get(CGF.CGM, dyn_cast_or_null<FunctionDecl>(FD));
232 static llvm::Constant *getPersonalityFn(CodeGenModule &CGM,
233 const EHPersonality &Personality) {
234 return CGM.CreateRuntimeFunction(llvm::FunctionType::get(CGM.Int32Ty, true),
235 Personality.PersonalityFn,
236 llvm::AttributeList(), /*Local=*/true);
239 static llvm::Constant *getOpaquePersonalityFn(CodeGenModule &CGM,
240 const EHPersonality &Personality) {
241 llvm::Constant *Fn = getPersonalityFn(CGM, Personality);
242 return llvm::ConstantExpr::getBitCast(Fn, CGM.Int8PtrTy);
245 /// Check whether a landingpad instruction only uses C++ features.
246 static bool LandingPadHasOnlyCXXUses(llvm::LandingPadInst *LPI) {
247 for (unsigned I = 0, E = LPI->getNumClauses(); I != E; ++I) {
248 // Look for something that would've been returned by the ObjC
249 // runtime's GetEHType() method.
250 llvm::Value *Val = LPI->getClause(I)->stripPointerCasts();
251 if (LPI->isCatch(I)) {
252 // Check if the catch value has the ObjC prefix.
253 if (llvm::GlobalVariable *GV = dyn_cast<llvm::GlobalVariable>(Val))
254 // ObjC EH selector entries are always global variables with
255 // names starting like this.
256 if (GV->getName().startswith("OBJC_EHTYPE"))
259 // Check if any of the filter values have the ObjC prefix.
260 llvm::Constant *CVal = cast<llvm::Constant>(Val);
261 for (llvm::User::op_iterator
262 II = CVal->op_begin(), IE = CVal->op_end(); II != IE; ++II) {
263 if (llvm::GlobalVariable *GV =
264 cast<llvm::GlobalVariable>((*II)->stripPointerCasts()))
265 // ObjC EH selector entries are always global variables with
266 // names starting like this.
267 if (GV->getName().startswith("OBJC_EHTYPE"))
275 /// Check whether a personality function could reasonably be swapped
276 /// for a C++ personality function.
277 static bool PersonalityHasOnlyCXXUses(llvm::Constant *Fn) {
278 for (llvm::User *U : Fn->users()) {
279 // Conditionally white-list bitcasts.
280 if (llvm::ConstantExpr *CE = dyn_cast<llvm::ConstantExpr>(U)) {
281 if (CE->getOpcode() != llvm::Instruction::BitCast) return false;
282 if (!PersonalityHasOnlyCXXUses(CE))
287 // Otherwise it must be a function.
288 llvm::Function *F = dyn_cast<llvm::Function>(U);
289 if (!F) return false;
291 for (auto BB = F->begin(), E = F->end(); BB != E; ++BB) {
292 if (BB->isLandingPad())
293 if (!LandingPadHasOnlyCXXUses(BB->getLandingPadInst()))
301 /// Try to use the C++ personality function in ObjC++. Not doing this
302 /// can cause some incompatibilities with gcc, which is more
303 /// aggressive about only using the ObjC++ personality in a function
304 /// when it really needs it.
305 void CodeGenModule::SimplifyPersonality() {
306 // If we're not in ObjC++ -fexceptions, there's nothing to do.
307 if (!LangOpts.CPlusPlus || !LangOpts.ObjC1 || !LangOpts.Exceptions)
310 // Both the problem this endeavors to fix and the way the logic
311 // above works is specific to the NeXT runtime.
312 if (!LangOpts.ObjCRuntime.isNeXTFamily())
315 const EHPersonality &ObjCXX = EHPersonality::get(*this, /*FD=*/nullptr);
316 const EHPersonality &CXX =
317 getCXXPersonality(getTarget().getTriple(), LangOpts);
321 assert(std::strcmp(ObjCXX.PersonalityFn, CXX.PersonalityFn) != 0 &&
322 "Different EHPersonalities using the same personality function.");
324 llvm::Function *Fn = getModule().getFunction(ObjCXX.PersonalityFn);
326 // Nothing to do if it's unused.
327 if (!Fn || Fn->use_empty()) return;
329 // Can't do the optimization if it has non-C++ uses.
330 if (!PersonalityHasOnlyCXXUses(Fn)) return;
332 // Create the C++ personality function and kill off the old
334 llvm::Constant *CXXFn = getPersonalityFn(*this, CXX);
336 // This can happen if the user is screwing with us.
337 if (Fn->getType() != CXXFn->getType()) return;
339 Fn->replaceAllUsesWith(CXXFn);
340 Fn->eraseFromParent();
343 /// Returns the value to inject into a selector to indicate the
344 /// presence of a catch-all.
345 static llvm::Constant *getCatchAllValue(CodeGenFunction &CGF) {
346 // Possibly we should use @llvm.eh.catch.all.value here.
347 return llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
351 /// A cleanup to free the exception object if its initialization
353 struct FreeException final : EHScopeStack::Cleanup {
355 FreeException(llvm::Value *exn) : exn(exn) {}
356 void Emit(CodeGenFunction &CGF, Flags flags) override {
357 CGF.EmitNounwindRuntimeCall(getFreeExceptionFn(CGF.CGM), exn);
360 } // end anonymous namespace
362 // Emits an exception expression into the given location. This
363 // differs from EmitAnyExprToMem only in that, if a final copy-ctor
364 // call is required, an exception within that copy ctor causes
365 // std::terminate to be invoked.
366 void CodeGenFunction::EmitAnyExprToExn(const Expr *e, Address addr) {
367 // Make sure the exception object is cleaned up if there's an
368 // exception during initialization.
369 pushFullExprCleanup<FreeException>(EHCleanup, addr.getPointer());
370 EHScopeStack::stable_iterator cleanup = EHStack.stable_begin();
372 // __cxa_allocate_exception returns a void*; we need to cast this
373 // to the appropriate type for the object.
374 llvm::Type *ty = ConvertTypeForMem(e->getType())->getPointerTo();
375 Address typedAddr = Builder.CreateBitCast(addr, ty);
377 // FIXME: this isn't quite right! If there's a final unelided call
378 // to a copy constructor, then according to [except.terminate]p1 we
379 // must call std::terminate() if that constructor throws, because
380 // technically that copy occurs after the exception expression is
381 // evaluated but before the exception is caught. But the best way
382 // to handle that is to teach EmitAggExpr to do the final copy
383 // differently if it can't be elided.
384 EmitAnyExprToMem(e, typedAddr, e->getType().getQualifiers(),
387 // Deactivate the cleanup block.
388 DeactivateCleanupBlock(cleanup,
389 cast<llvm::Instruction>(typedAddr.getPointer()));
392 Address CodeGenFunction::getExceptionSlot() {
394 ExceptionSlot = CreateTempAlloca(Int8PtrTy, "exn.slot");
395 return Address(ExceptionSlot, getPointerAlign());
398 Address CodeGenFunction::getEHSelectorSlot() {
400 EHSelectorSlot = CreateTempAlloca(Int32Ty, "ehselector.slot");
401 return Address(EHSelectorSlot, CharUnits::fromQuantity(4));
404 llvm::Value *CodeGenFunction::getExceptionFromSlot() {
405 return Builder.CreateLoad(getExceptionSlot(), "exn");
408 llvm::Value *CodeGenFunction::getSelectorFromSlot() {
409 return Builder.CreateLoad(getEHSelectorSlot(), "sel");
412 void CodeGenFunction::EmitCXXThrowExpr(const CXXThrowExpr *E,
413 bool KeepInsertionPoint) {
414 if (const Expr *SubExpr = E->getSubExpr()) {
415 QualType ThrowType = SubExpr->getType();
416 if (ThrowType->isObjCObjectPointerType()) {
417 const Stmt *ThrowStmt = E->getSubExpr();
418 const ObjCAtThrowStmt S(E->getExprLoc(), const_cast<Stmt *>(ThrowStmt));
419 CGM.getObjCRuntime().EmitThrowStmt(*this, S, false);
421 CGM.getCXXABI().emitThrow(*this, E);
424 CGM.getCXXABI().emitRethrow(*this, /*isNoReturn=*/true);
427 // throw is an expression, and the expression emitters expect us
428 // to leave ourselves at a valid insertion point.
429 if (KeepInsertionPoint)
430 EmitBlock(createBasicBlock("throw.cont"));
433 void CodeGenFunction::EmitStartEHSpec(const Decl *D) {
434 if (!CGM.getLangOpts().CXXExceptions)
437 const FunctionDecl* FD = dyn_cast_or_null<FunctionDecl>(D);
439 // Check if CapturedDecl is nothrow and create terminate scope for it.
440 if (const CapturedDecl* CD = dyn_cast_or_null<CapturedDecl>(D)) {
442 EHStack.pushTerminate();
446 const FunctionProtoType *Proto = FD->getType()->getAs<FunctionProtoType>();
450 ExceptionSpecificationType EST = Proto->getExceptionSpecType();
451 if (isNoexceptExceptionSpec(EST)) {
452 if (Proto->getNoexceptSpec(getContext()) == FunctionProtoType::NR_Nothrow) {
453 // noexcept functions are simple terminate scopes.
454 EHStack.pushTerminate();
456 } else if (EST == EST_Dynamic || EST == EST_DynamicNone) {
457 // TODO: Revisit exception specifications for the MS ABI. There is a way to
458 // encode these in an object file but MSVC doesn't do anything with it.
459 if (getTarget().getCXXABI().isMicrosoft())
461 unsigned NumExceptions = Proto->getNumExceptions();
462 EHFilterScope *Filter = EHStack.pushFilter(NumExceptions);
464 for (unsigned I = 0; I != NumExceptions; ++I) {
465 QualType Ty = Proto->getExceptionType(I);
466 QualType ExceptType = Ty.getNonReferenceType().getUnqualifiedType();
467 llvm::Value *EHType = CGM.GetAddrOfRTTIDescriptor(ExceptType,
469 Filter->setFilter(I, EHType);
474 /// Emit the dispatch block for a filter scope if necessary.
475 static void emitFilterDispatchBlock(CodeGenFunction &CGF,
476 EHFilterScope &filterScope) {
477 llvm::BasicBlock *dispatchBlock = filterScope.getCachedEHDispatchBlock();
478 if (!dispatchBlock) return;
479 if (dispatchBlock->use_empty()) {
480 delete dispatchBlock;
484 CGF.EmitBlockAfterUses(dispatchBlock);
486 // If this isn't a catch-all filter, we need to check whether we got
487 // here because the filter triggered.
488 if (filterScope.getNumFilters()) {
489 // Load the selector value.
490 llvm::Value *selector = CGF.getSelectorFromSlot();
491 llvm::BasicBlock *unexpectedBB = CGF.createBasicBlock("ehspec.unexpected");
493 llvm::Value *zero = CGF.Builder.getInt32(0);
494 llvm::Value *failsFilter =
495 CGF.Builder.CreateICmpSLT(selector, zero, "ehspec.fails");
496 CGF.Builder.CreateCondBr(failsFilter, unexpectedBB,
497 CGF.getEHResumeBlock(false));
499 CGF.EmitBlock(unexpectedBB);
502 // Call __cxa_call_unexpected. This doesn't need to be an invoke
503 // because __cxa_call_unexpected magically filters exceptions
504 // according to the last landing pad the exception was thrown
506 llvm::Value *exn = CGF.getExceptionFromSlot();
507 CGF.EmitRuntimeCall(getUnexpectedFn(CGF.CGM), exn)
508 ->setDoesNotReturn();
509 CGF.Builder.CreateUnreachable();
512 void CodeGenFunction::EmitEndEHSpec(const Decl *D) {
513 if (!CGM.getLangOpts().CXXExceptions)
516 const FunctionDecl* FD = dyn_cast_or_null<FunctionDecl>(D);
518 // Check if CapturedDecl is nothrow and pop terminate scope for it.
519 if (const CapturedDecl* CD = dyn_cast_or_null<CapturedDecl>(D)) {
521 EHStack.popTerminate();
525 const FunctionProtoType *Proto = FD->getType()->getAs<FunctionProtoType>();
529 ExceptionSpecificationType EST = Proto->getExceptionSpecType();
530 if (isNoexceptExceptionSpec(EST)) {
531 if (Proto->getNoexceptSpec(getContext()) == FunctionProtoType::NR_Nothrow) {
532 EHStack.popTerminate();
534 } else if (EST == EST_Dynamic || EST == EST_DynamicNone) {
535 // TODO: Revisit exception specifications for the MS ABI. There is a way to
536 // encode these in an object file but MSVC doesn't do anything with it.
537 if (getTarget().getCXXABI().isMicrosoft())
539 EHFilterScope &filterScope = cast<EHFilterScope>(*EHStack.begin());
540 emitFilterDispatchBlock(*this, filterScope);
545 void CodeGenFunction::EmitCXXTryStmt(const CXXTryStmt &S) {
547 EmitStmt(S.getTryBlock());
551 void CodeGenFunction::EnterCXXTryStmt(const CXXTryStmt &S, bool IsFnTryBlock) {
552 unsigned NumHandlers = S.getNumHandlers();
553 EHCatchScope *CatchScope = EHStack.pushCatch(NumHandlers);
555 for (unsigned I = 0; I != NumHandlers; ++I) {
556 const CXXCatchStmt *C = S.getHandler(I);
558 llvm::BasicBlock *Handler = createBasicBlock("catch");
559 if (C->getExceptionDecl()) {
560 // FIXME: Dropping the reference type on the type into makes it
561 // impossible to correctly implement catch-by-reference
562 // semantics for pointers. Unfortunately, this is what all
563 // existing compilers do, and it's not clear that the standard
564 // personality routine is capable of doing this right. See C++ DR 388:
565 // http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#388
566 Qualifiers CaughtTypeQuals;
567 QualType CaughtType = CGM.getContext().getUnqualifiedArrayType(
568 C->getCaughtType().getNonReferenceType(), CaughtTypeQuals);
570 CatchTypeInfo TypeInfo{nullptr, 0};
571 if (CaughtType->isObjCObjectPointerType())
572 TypeInfo.RTTI = CGM.getObjCRuntime().GetEHType(CaughtType);
574 TypeInfo = CGM.getCXXABI().getAddrOfCXXCatchHandlerType(
575 CaughtType, C->getCaughtType());
576 CatchScope->setHandler(I, TypeInfo, Handler);
578 // No exception decl indicates '...', a catch-all.
579 CatchScope->setHandler(I, CGM.getCXXABI().getCatchAllTypeInfo(), Handler);
585 CodeGenFunction::getEHDispatchBlock(EHScopeStack::stable_iterator si) {
586 if (EHPersonality::get(*this).usesFuncletPads())
587 return getMSVCDispatchBlock(si);
589 // The dispatch block for the end of the scope chain is a block that
590 // just resumes unwinding.
591 if (si == EHStack.stable_end())
592 return getEHResumeBlock(true);
594 // Otherwise, we should look at the actual scope.
595 EHScope &scope = *EHStack.find(si);
597 llvm::BasicBlock *dispatchBlock = scope.getCachedEHDispatchBlock();
598 if (!dispatchBlock) {
599 switch (scope.getKind()) {
600 case EHScope::Catch: {
601 // Apply a special case to a single catch-all.
602 EHCatchScope &catchScope = cast<EHCatchScope>(scope);
603 if (catchScope.getNumHandlers() == 1 &&
604 catchScope.getHandler(0).isCatchAll()) {
605 dispatchBlock = catchScope.getHandler(0).Block;
607 // Otherwise, make a dispatch block.
609 dispatchBlock = createBasicBlock("catch.dispatch");
614 case EHScope::Cleanup:
615 dispatchBlock = createBasicBlock("ehcleanup");
618 case EHScope::Filter:
619 dispatchBlock = createBasicBlock("filter.dispatch");
622 case EHScope::Terminate:
623 dispatchBlock = getTerminateHandler();
626 case EHScope::PadEnd:
627 llvm_unreachable("PadEnd unnecessary for Itanium!");
629 scope.setCachedEHDispatchBlock(dispatchBlock);
631 return dispatchBlock;
635 CodeGenFunction::getMSVCDispatchBlock(EHScopeStack::stable_iterator SI) {
636 // Returning nullptr indicates that the previous dispatch block should unwind
638 if (SI == EHStack.stable_end())
641 // Otherwise, we should look at the actual scope.
642 EHScope &EHS = *EHStack.find(SI);
644 llvm::BasicBlock *DispatchBlock = EHS.getCachedEHDispatchBlock();
646 return DispatchBlock;
648 if (EHS.getKind() == EHScope::Terminate)
649 DispatchBlock = getTerminateHandler();
651 DispatchBlock = createBasicBlock();
652 CGBuilderTy Builder(*this, DispatchBlock);
654 switch (EHS.getKind()) {
656 DispatchBlock->setName("catch.dispatch");
659 case EHScope::Cleanup:
660 DispatchBlock->setName("ehcleanup");
663 case EHScope::Filter:
664 llvm_unreachable("exception specifications not handled yet!");
666 case EHScope::Terminate:
667 DispatchBlock->setName("terminate");
670 case EHScope::PadEnd:
671 llvm_unreachable("PadEnd dispatch block missing!");
673 EHS.setCachedEHDispatchBlock(DispatchBlock);
674 return DispatchBlock;
677 /// Check whether this is a non-EH scope, i.e. a scope which doesn't
678 /// affect exception handling. Currently, the only non-EH scopes are
679 /// normal-only cleanup scopes.
680 static bool isNonEHScope(const EHScope &S) {
681 switch (S.getKind()) {
682 case EHScope::Cleanup:
683 return !cast<EHCleanupScope>(S).isEHCleanup();
684 case EHScope::Filter:
686 case EHScope::Terminate:
687 case EHScope::PadEnd:
691 llvm_unreachable("Invalid EHScope Kind!");
694 llvm::BasicBlock *CodeGenFunction::getInvokeDestImpl() {
695 assert(EHStack.requiresLandingPad());
696 assert(!EHStack.empty());
698 // If exceptions are disabled and SEH is not in use, then there is no invoke
699 // destination. SEH "works" even if exceptions are off. In practice, this
700 // means that C++ destructors and other EH cleanups don't run, which is
701 // consistent with MSVC's behavior.
702 const LangOptions &LO = CGM.getLangOpts();
703 if (!LO.Exceptions) {
704 if (!LO.Borland && !LO.MicrosoftExt)
706 if (!currentFunctionUsesSEHTry())
710 // CUDA device code doesn't have exceptions.
711 if (LO.CUDA && LO.CUDAIsDevice)
714 // Check the innermost scope for a cached landing pad. If this is
715 // a non-EH cleanup, we'll check enclosing scopes in EmitLandingPad.
716 llvm::BasicBlock *LP = EHStack.begin()->getCachedLandingPad();
719 const EHPersonality &Personality = EHPersonality::get(*this);
721 if (!CurFn->hasPersonalityFn())
722 CurFn->setPersonalityFn(getOpaquePersonalityFn(CGM, Personality));
724 if (Personality.usesFuncletPads()) {
725 // We don't need separate landing pads in the funclet model.
726 LP = getEHDispatchBlock(EHStack.getInnermostEHScope());
728 // Build the landing pad for this scope.
729 LP = EmitLandingPad();
734 // Cache the landing pad on the innermost scope. If this is a
735 // non-EH scope, cache the landing pad on the enclosing scope, too.
736 for (EHScopeStack::iterator ir = EHStack.begin(); true; ++ir) {
737 ir->setCachedLandingPad(LP);
738 if (!isNonEHScope(*ir)) break;
744 llvm::BasicBlock *CodeGenFunction::EmitLandingPad() {
745 assert(EHStack.requiresLandingPad());
747 EHScope &innermostEHScope = *EHStack.find(EHStack.getInnermostEHScope());
748 switch (innermostEHScope.getKind()) {
749 case EHScope::Terminate:
750 return getTerminateLandingPad();
752 case EHScope::PadEnd:
753 llvm_unreachable("PadEnd unnecessary for Itanium!");
756 case EHScope::Cleanup:
757 case EHScope::Filter:
758 if (llvm::BasicBlock *lpad = innermostEHScope.getCachedLandingPad())
762 // Save the current IR generation state.
763 CGBuilderTy::InsertPoint savedIP = Builder.saveAndClearIP();
764 auto DL = ApplyDebugLocation::CreateDefaultArtificial(*this, CurEHLocation);
766 // Create and configure the landing pad.
767 llvm::BasicBlock *lpad = createBasicBlock("lpad");
770 llvm::LandingPadInst *LPadInst =
771 Builder.CreateLandingPad(llvm::StructType::get(Int8PtrTy, Int32Ty), 0);
773 llvm::Value *LPadExn = Builder.CreateExtractValue(LPadInst, 0);
774 Builder.CreateStore(LPadExn, getExceptionSlot());
775 llvm::Value *LPadSel = Builder.CreateExtractValue(LPadInst, 1);
776 Builder.CreateStore(LPadSel, getEHSelectorSlot());
778 // Save the exception pointer. It's safe to use a single exception
779 // pointer per function because EH cleanups can never have nested
781 // Build the landingpad instruction.
783 // Accumulate all the handlers in scope.
784 bool hasCatchAll = false;
785 bool hasCleanup = false;
786 bool hasFilter = false;
787 SmallVector<llvm::Value*, 4> filterTypes;
788 llvm::SmallPtrSet<llvm::Value*, 4> catchTypes;
789 for (EHScopeStack::iterator I = EHStack.begin(), E = EHStack.end(); I != E;
792 switch (I->getKind()) {
793 case EHScope::Cleanup:
794 // If we have a cleanup, remember that.
795 hasCleanup = (hasCleanup || cast<EHCleanupScope>(*I).isEHCleanup());
798 case EHScope::Filter: {
799 assert(I.next() == EHStack.end() && "EH filter is not end of EH stack");
800 assert(!hasCatchAll && "EH filter reached after catch-all");
802 // Filter scopes get added to the landingpad in weird ways.
803 EHFilterScope &filter = cast<EHFilterScope>(*I);
806 // Add all the filter values.
807 for (unsigned i = 0, e = filter.getNumFilters(); i != e; ++i)
808 filterTypes.push_back(filter.getFilter(i));
812 case EHScope::Terminate:
813 // Terminate scopes are basically catch-alls.
814 assert(!hasCatchAll);
821 case EHScope::PadEnd:
822 llvm_unreachable("PadEnd unnecessary for Itanium!");
825 EHCatchScope &catchScope = cast<EHCatchScope>(*I);
826 for (unsigned hi = 0, he = catchScope.getNumHandlers(); hi != he; ++hi) {
827 EHCatchScope::Handler handler = catchScope.getHandler(hi);
828 assert(handler.Type.Flags == 0 &&
829 "landingpads do not support catch handler flags");
831 // If this is a catch-all, register that and abort.
832 if (!handler.Type.RTTI) {
833 assert(!hasCatchAll);
838 // Check whether we already have a handler for this type.
839 if (catchTypes.insert(handler.Type.RTTI).second)
840 // If not, add it directly to the landingpad.
841 LPadInst->addClause(handler.Type.RTTI);
846 // If we have a catch-all, add null to the landingpad.
847 assert(!(hasCatchAll && hasFilter));
849 LPadInst->addClause(getCatchAllValue(*this));
851 // If we have an EH filter, we need to add those handlers in the
852 // right place in the landingpad, which is to say, at the end.
853 } else if (hasFilter) {
854 // Create a filter expression: a constant array indicating which filter
855 // types there are. The personality routine only lands here if the filter
857 SmallVector<llvm::Constant*, 8> Filters;
858 llvm::ArrayType *AType =
859 llvm::ArrayType::get(!filterTypes.empty() ?
860 filterTypes[0]->getType() : Int8PtrTy,
863 for (unsigned i = 0, e = filterTypes.size(); i != e; ++i)
864 Filters.push_back(cast<llvm::Constant>(filterTypes[i]));
865 llvm::Constant *FilterArray = llvm::ConstantArray::get(AType, Filters);
866 LPadInst->addClause(FilterArray);
868 // Also check whether we need a cleanup.
870 LPadInst->setCleanup(true);
872 // Otherwise, signal that we at least have cleanups.
873 } else if (hasCleanup) {
874 LPadInst->setCleanup(true);
877 assert((LPadInst->getNumClauses() > 0 || LPadInst->isCleanup()) &&
878 "landingpad instruction has no clauses!");
880 // Tell the backend how to generate the landing pad.
881 Builder.CreateBr(getEHDispatchBlock(EHStack.getInnermostEHScope()));
883 // Restore the old IR generation state.
884 Builder.restoreIP(savedIP);
889 static void emitCatchPadBlock(CodeGenFunction &CGF, EHCatchScope &CatchScope) {
890 llvm::BasicBlock *DispatchBlock = CatchScope.getCachedEHDispatchBlock();
891 assert(DispatchBlock);
893 CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveIP();
894 CGF.EmitBlockAfterUses(DispatchBlock);
896 llvm::Value *ParentPad = CGF.CurrentFuncletPad;
898 ParentPad = llvm::ConstantTokenNone::get(CGF.getLLVMContext());
899 llvm::BasicBlock *UnwindBB =
900 CGF.getEHDispatchBlock(CatchScope.getEnclosingEHScope());
902 unsigned NumHandlers = CatchScope.getNumHandlers();
903 llvm::CatchSwitchInst *CatchSwitch =
904 CGF.Builder.CreateCatchSwitch(ParentPad, UnwindBB, NumHandlers);
906 // Test against each of the exception types we claim to catch.
907 for (unsigned I = 0; I < NumHandlers; ++I) {
908 const EHCatchScope::Handler &Handler = CatchScope.getHandler(I);
910 CatchTypeInfo TypeInfo = Handler.Type;
912 TypeInfo.RTTI = llvm::Constant::getNullValue(CGF.VoidPtrTy);
914 CGF.Builder.SetInsertPoint(Handler.Block);
916 if (EHPersonality::get(CGF).isMSVCXXPersonality()) {
917 CGF.Builder.CreateCatchPad(
918 CatchSwitch, {TypeInfo.RTTI, CGF.Builder.getInt32(TypeInfo.Flags),
919 llvm::Constant::getNullValue(CGF.VoidPtrTy)});
921 CGF.Builder.CreateCatchPad(CatchSwitch, {TypeInfo.RTTI});
924 CatchSwitch->addHandler(Handler.Block);
926 CGF.Builder.restoreIP(SavedIP);
929 /// Emit the structure of the dispatch block for the given catch scope.
930 /// It is an invariant that the dispatch block already exists.
931 static void emitCatchDispatchBlock(CodeGenFunction &CGF,
932 EHCatchScope &catchScope) {
933 if (EHPersonality::get(CGF).usesFuncletPads())
934 return emitCatchPadBlock(CGF, catchScope);
936 llvm::BasicBlock *dispatchBlock = catchScope.getCachedEHDispatchBlock();
937 assert(dispatchBlock);
939 // If there's only a single catch-all, getEHDispatchBlock returned
940 // that catch-all as the dispatch block.
941 if (catchScope.getNumHandlers() == 1 &&
942 catchScope.getHandler(0).isCatchAll()) {
943 assert(dispatchBlock == catchScope.getHandler(0).Block);
947 CGBuilderTy::InsertPoint savedIP = CGF.Builder.saveIP();
948 CGF.EmitBlockAfterUses(dispatchBlock);
950 // Select the right handler.
951 llvm::Value *llvm_eh_typeid_for =
952 CGF.CGM.getIntrinsic(llvm::Intrinsic::eh_typeid_for);
954 // Load the selector value.
955 llvm::Value *selector = CGF.getSelectorFromSlot();
957 // Test against each of the exception types we claim to catch.
958 for (unsigned i = 0, e = catchScope.getNumHandlers(); ; ++i) {
959 assert(i < e && "ran off end of handlers!");
960 const EHCatchScope::Handler &handler = catchScope.getHandler(i);
962 llvm::Value *typeValue = handler.Type.RTTI;
963 assert(handler.Type.Flags == 0 &&
964 "landingpads do not support catch handler flags");
965 assert(typeValue && "fell into catch-all case!");
966 typeValue = CGF.Builder.CreateBitCast(typeValue, CGF.Int8PtrTy);
968 // Figure out the next block.
970 llvm::BasicBlock *nextBlock;
972 // If this is the last handler, we're at the end, and the next
973 // block is the block for the enclosing EH scope.
975 nextBlock = CGF.getEHDispatchBlock(catchScope.getEnclosingEHScope());
978 // If the next handler is a catch-all, we're at the end, and the
979 // next block is that handler.
980 } else if (catchScope.getHandler(i+1).isCatchAll()) {
981 nextBlock = catchScope.getHandler(i+1).Block;
984 // Otherwise, we're not at the end and we need a new block.
986 nextBlock = CGF.createBasicBlock("catch.fallthrough");
990 // Figure out the catch type's index in the LSDA's type table.
991 llvm::CallInst *typeIndex =
992 CGF.Builder.CreateCall(llvm_eh_typeid_for, typeValue);
993 typeIndex->setDoesNotThrow();
995 llvm::Value *matchesTypeIndex =
996 CGF.Builder.CreateICmpEQ(selector, typeIndex, "matches");
997 CGF.Builder.CreateCondBr(matchesTypeIndex, handler.Block, nextBlock);
999 // If the next handler is a catch-all, we're completely done.
1001 CGF.Builder.restoreIP(savedIP);
1004 // Otherwise we need to emit and continue at that block.
1005 CGF.EmitBlock(nextBlock);
1009 void CodeGenFunction::popCatchScope() {
1010 EHCatchScope &catchScope = cast<EHCatchScope>(*EHStack.begin());
1011 if (catchScope.hasEHBranches())
1012 emitCatchDispatchBlock(*this, catchScope);
1016 void CodeGenFunction::ExitCXXTryStmt(const CXXTryStmt &S, bool IsFnTryBlock) {
1017 unsigned NumHandlers = S.getNumHandlers();
1018 EHCatchScope &CatchScope = cast<EHCatchScope>(*EHStack.begin());
1019 assert(CatchScope.getNumHandlers() == NumHandlers);
1021 // If the catch was not required, bail out now.
1022 if (!CatchScope.hasEHBranches()) {
1023 CatchScope.clearHandlerBlocks();
1028 // Emit the structure of the EH dispatch for this catch.
1029 emitCatchDispatchBlock(*this, CatchScope);
1031 // Copy the handler blocks off before we pop the EH stack. Emitting
1032 // the handlers might scribble on this memory.
1033 SmallVector<EHCatchScope::Handler, 8> Handlers(
1034 CatchScope.begin(), CatchScope.begin() + NumHandlers);
1038 // The fall-through block.
1039 llvm::BasicBlock *ContBB = createBasicBlock("try.cont");
1041 // We just emitted the body of the try; jump to the continue block.
1042 if (HaveInsertPoint())
1043 Builder.CreateBr(ContBB);
1045 // Determine if we need an implicit rethrow for all these catch handlers;
1046 // see the comment below.
1047 bool doImplicitRethrow = false;
1049 doImplicitRethrow = isa<CXXDestructorDecl>(CurCodeDecl) ||
1050 isa<CXXConstructorDecl>(CurCodeDecl);
1052 // Perversely, we emit the handlers backwards precisely because we
1053 // want them to appear in source order. In all of these cases, the
1054 // catch block will have exactly one predecessor, which will be a
1055 // particular block in the catch dispatch. However, in the case of
1056 // a catch-all, one of the dispatch blocks will branch to two
1057 // different handlers, and EmitBlockAfterUses will cause the second
1058 // handler to be moved before the first.
1059 for (unsigned I = NumHandlers; I != 0; --I) {
1060 llvm::BasicBlock *CatchBlock = Handlers[I-1].Block;
1061 EmitBlockAfterUses(CatchBlock);
1063 // Catch the exception if this isn't a catch-all.
1064 const CXXCatchStmt *C = S.getHandler(I-1);
1066 // Enter a cleanup scope, including the catch variable and the
1068 RunCleanupsScope CatchScope(*this);
1070 // Initialize the catch variable and set up the cleanups.
1071 SaveAndRestore<llvm::Instruction *> RestoreCurrentFuncletPad(
1073 CGM.getCXXABI().emitBeginCatch(*this, C);
1075 // Emit the PGO counter increment.
1076 incrementProfileCounter(C);
1078 // Perform the body of the catch.
1079 EmitStmt(C->getHandlerBlock());
1081 // [except.handle]p11:
1082 // The currently handled exception is rethrown if control
1083 // reaches the end of a handler of the function-try-block of a
1084 // constructor or destructor.
1086 // It is important that we only do this on fallthrough and not on
1087 // return. Note that it's illegal to put a return in a
1088 // constructor function-try-block's catch handler (p14), so this
1089 // really only applies to destructors.
1090 if (doImplicitRethrow && HaveInsertPoint()) {
1091 CGM.getCXXABI().emitRethrow(*this, /*isNoReturn*/false);
1092 Builder.CreateUnreachable();
1093 Builder.ClearInsertionPoint();
1096 // Fall out through the catch cleanups.
1097 CatchScope.ForceCleanup();
1099 // Branch out of the try.
1100 if (HaveInsertPoint())
1101 Builder.CreateBr(ContBB);
1105 incrementProfileCounter(&S);
1109 struct CallEndCatchForFinally final : EHScopeStack::Cleanup {
1110 llvm::Value *ForEHVar;
1111 llvm::Value *EndCatchFn;
1112 CallEndCatchForFinally(llvm::Value *ForEHVar, llvm::Value *EndCatchFn)
1113 : ForEHVar(ForEHVar), EndCatchFn(EndCatchFn) {}
1115 void Emit(CodeGenFunction &CGF, Flags flags) override {
1116 llvm::BasicBlock *EndCatchBB = CGF.createBasicBlock("finally.endcatch");
1117 llvm::BasicBlock *CleanupContBB =
1118 CGF.createBasicBlock("finally.cleanup.cont");
1120 llvm::Value *ShouldEndCatch =
1121 CGF.Builder.CreateFlagLoad(ForEHVar, "finally.endcatch");
1122 CGF.Builder.CreateCondBr(ShouldEndCatch, EndCatchBB, CleanupContBB);
1123 CGF.EmitBlock(EndCatchBB);
1124 CGF.EmitRuntimeCallOrInvoke(EndCatchFn); // catch-all, so might throw
1125 CGF.EmitBlock(CleanupContBB);
1129 struct PerformFinally final : EHScopeStack::Cleanup {
1131 llvm::Value *ForEHVar;
1132 llvm::Value *EndCatchFn;
1133 llvm::Value *RethrowFn;
1134 llvm::Value *SavedExnVar;
1136 PerformFinally(const Stmt *Body, llvm::Value *ForEHVar,
1137 llvm::Value *EndCatchFn,
1138 llvm::Value *RethrowFn, llvm::Value *SavedExnVar)
1139 : Body(Body), ForEHVar(ForEHVar), EndCatchFn(EndCatchFn),
1140 RethrowFn(RethrowFn), SavedExnVar(SavedExnVar) {}
1142 void Emit(CodeGenFunction &CGF, Flags flags) override {
1143 // Enter a cleanup to call the end-catch function if one was provided.
1145 CGF.EHStack.pushCleanup<CallEndCatchForFinally>(NormalAndEHCleanup,
1146 ForEHVar, EndCatchFn);
1148 // Save the current cleanup destination in case there are
1149 // cleanups in the finally block.
1150 llvm::Value *SavedCleanupDest =
1151 CGF.Builder.CreateLoad(CGF.getNormalCleanupDestSlot(),
1152 "cleanup.dest.saved");
1154 // Emit the finally block.
1157 // If the end of the finally is reachable, check whether this was
1158 // for EH. If so, rethrow.
1159 if (CGF.HaveInsertPoint()) {
1160 llvm::BasicBlock *RethrowBB = CGF.createBasicBlock("finally.rethrow");
1161 llvm::BasicBlock *ContBB = CGF.createBasicBlock("finally.cont");
1163 llvm::Value *ShouldRethrow =
1164 CGF.Builder.CreateFlagLoad(ForEHVar, "finally.shouldthrow");
1165 CGF.Builder.CreateCondBr(ShouldRethrow, RethrowBB, ContBB);
1167 CGF.EmitBlock(RethrowBB);
1169 CGF.EmitRuntimeCallOrInvoke(RethrowFn,
1170 CGF.Builder.CreateAlignedLoad(SavedExnVar, CGF.getPointerAlign()));
1172 CGF.EmitRuntimeCallOrInvoke(RethrowFn);
1174 CGF.Builder.CreateUnreachable();
1176 CGF.EmitBlock(ContBB);
1178 // Restore the cleanup destination.
1179 CGF.Builder.CreateStore(SavedCleanupDest,
1180 CGF.getNormalCleanupDestSlot());
1183 // Leave the end-catch cleanup. As an optimization, pretend that
1184 // the fallthrough path was inaccessible; we've dynamically proven
1185 // that we're not in the EH case along that path.
1187 CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveAndClearIP();
1188 CGF.PopCleanupBlock();
1189 CGF.Builder.restoreIP(SavedIP);
1192 // Now make sure we actually have an insertion point or the
1193 // cleanup gods will hate us.
1194 CGF.EnsureInsertPoint();
1197 } // end anonymous namespace
1199 /// Enters a finally block for an implementation using zero-cost
1200 /// exceptions. This is mostly general, but hard-codes some
1201 /// language/ABI-specific behavior in the catch-all sections.
1202 void CodeGenFunction::FinallyInfo::enter(CodeGenFunction &CGF,
1204 llvm::Constant *beginCatchFn,
1205 llvm::Constant *endCatchFn,
1206 llvm::Constant *rethrowFn) {
1207 assert((beginCatchFn != nullptr) == (endCatchFn != nullptr) &&
1208 "begin/end catch functions not paired");
1209 assert(rethrowFn && "rethrow function is required");
1211 BeginCatchFn = beginCatchFn;
1213 // The rethrow function has one of the following two types:
1216 // In the latter case we need to pass it the exception object.
1217 // But we can't use the exception slot because the @finally might
1218 // have a landing pad (which would overwrite the exception slot).
1219 llvm::FunctionType *rethrowFnTy =
1220 cast<llvm::FunctionType>(
1221 cast<llvm::PointerType>(rethrowFn->getType())->getElementType());
1222 SavedExnVar = nullptr;
1223 if (rethrowFnTy->getNumParams())
1224 SavedExnVar = CGF.CreateTempAlloca(CGF.Int8PtrTy, "finally.exn");
1226 // A finally block is a statement which must be executed on any edge
1227 // out of a given scope. Unlike a cleanup, the finally block may
1228 // contain arbitrary control flow leading out of itself. In
1229 // addition, finally blocks should always be executed, even if there
1230 // are no catch handlers higher on the stack. Therefore, we
1231 // surround the protected scope with a combination of a normal
1232 // cleanup (to catch attempts to break out of the block via normal
1233 // control flow) and an EH catch-all (semantically "outside" any try
1234 // statement to which the finally block might have been attached).
1235 // The finally block itself is generated in the context of a cleanup
1236 // which conditionally leaves the catch-all.
1238 // Jump destination for performing the finally block on an exception
1239 // edge. We'll never actually reach this block, so unreachable is
1241 RethrowDest = CGF.getJumpDestInCurrentScope(CGF.getUnreachableBlock());
1243 // Whether the finally block is being executed for EH purposes.
1244 ForEHVar = CGF.CreateTempAlloca(CGF.Builder.getInt1Ty(), "finally.for-eh");
1245 CGF.Builder.CreateFlagStore(false, ForEHVar);
1247 // Enter a normal cleanup which will perform the @finally block.
1248 CGF.EHStack.pushCleanup<PerformFinally>(NormalCleanup, body,
1249 ForEHVar, endCatchFn,
1250 rethrowFn, SavedExnVar);
1252 // Enter a catch-all scope.
1253 llvm::BasicBlock *catchBB = CGF.createBasicBlock("finally.catchall");
1254 EHCatchScope *catchScope = CGF.EHStack.pushCatch(1);
1255 catchScope->setCatchAllHandler(0, catchBB);
1258 void CodeGenFunction::FinallyInfo::exit(CodeGenFunction &CGF) {
1259 // Leave the finally catch-all.
1260 EHCatchScope &catchScope = cast<EHCatchScope>(*CGF.EHStack.begin());
1261 llvm::BasicBlock *catchBB = catchScope.getHandler(0).Block;
1263 CGF.popCatchScope();
1265 // If there are any references to the catch-all block, emit it.
1266 if (catchBB->use_empty()) {
1269 CGBuilderTy::InsertPoint savedIP = CGF.Builder.saveAndClearIP();
1270 CGF.EmitBlock(catchBB);
1272 llvm::Value *exn = nullptr;
1274 // If there's a begin-catch function, call it.
1276 exn = CGF.getExceptionFromSlot();
1277 CGF.EmitNounwindRuntimeCall(BeginCatchFn, exn);
1280 // If we need to remember the exception pointer to rethrow later, do so.
1282 if (!exn) exn = CGF.getExceptionFromSlot();
1283 CGF.Builder.CreateAlignedStore(exn, SavedExnVar, CGF.getPointerAlign());
1286 // Tell the cleanups in the finally block that we're do this for EH.
1287 CGF.Builder.CreateFlagStore(true, ForEHVar);
1289 // Thread a jump through the finally cleanup.
1290 CGF.EmitBranchThroughCleanup(RethrowDest);
1292 CGF.Builder.restoreIP(savedIP);
1295 // Finally, leave the @finally cleanup.
1296 CGF.PopCleanupBlock();
1299 llvm::BasicBlock *CodeGenFunction::getTerminateLandingPad() {
1300 if (TerminateLandingPad)
1301 return TerminateLandingPad;
1303 CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
1305 // This will get inserted at the end of the function.
1306 TerminateLandingPad = createBasicBlock("terminate.lpad");
1307 Builder.SetInsertPoint(TerminateLandingPad);
1309 // Tell the backend that this is a landing pad.
1310 const EHPersonality &Personality = EHPersonality::get(*this);
1312 if (!CurFn->hasPersonalityFn())
1313 CurFn->setPersonalityFn(getOpaquePersonalityFn(CGM, Personality));
1315 llvm::LandingPadInst *LPadInst =
1316 Builder.CreateLandingPad(llvm::StructType::get(Int8PtrTy, Int32Ty), 0);
1317 LPadInst->addClause(getCatchAllValue(*this));
1319 llvm::Value *Exn = nullptr;
1320 if (getLangOpts().CPlusPlus)
1321 Exn = Builder.CreateExtractValue(LPadInst, 0);
1322 llvm::CallInst *terminateCall =
1323 CGM.getCXXABI().emitTerminateForUnexpectedException(*this, Exn);
1324 terminateCall->setDoesNotReturn();
1325 Builder.CreateUnreachable();
1327 // Restore the saved insertion state.
1328 Builder.restoreIP(SavedIP);
1330 return TerminateLandingPad;
1333 llvm::BasicBlock *CodeGenFunction::getTerminateHandler() {
1334 if (TerminateHandler)
1335 return TerminateHandler;
1337 CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
1339 // Set up the terminate handler. This block is inserted at the very
1340 // end of the function by FinishFunction.
1341 TerminateHandler = createBasicBlock("terminate.handler");
1342 Builder.SetInsertPoint(TerminateHandler);
1343 llvm::Value *Exn = nullptr;
1344 SaveAndRestore<llvm::Instruction *> RestoreCurrentFuncletPad(
1346 if (EHPersonality::get(*this).usesFuncletPads()) {
1347 llvm::Value *ParentPad = CurrentFuncletPad;
1349 ParentPad = llvm::ConstantTokenNone::get(CGM.getLLVMContext());
1350 CurrentFuncletPad = Builder.CreateCleanupPad(ParentPad);
1352 if (getLangOpts().CPlusPlus)
1353 Exn = getExceptionFromSlot();
1355 llvm::CallInst *terminateCall =
1356 CGM.getCXXABI().emitTerminateForUnexpectedException(*this, Exn);
1357 terminateCall->setDoesNotReturn();
1358 Builder.CreateUnreachable();
1360 // Restore the saved insertion state.
1361 Builder.restoreIP(SavedIP);
1363 return TerminateHandler;
1366 llvm::BasicBlock *CodeGenFunction::getEHResumeBlock(bool isCleanup) {
1367 if (EHResumeBlock) return EHResumeBlock;
1369 CGBuilderTy::InsertPoint SavedIP = Builder.saveIP();
1371 // We emit a jump to a notional label at the outermost unwind state.
1372 EHResumeBlock = createBasicBlock("eh.resume");
1373 Builder.SetInsertPoint(EHResumeBlock);
1375 const EHPersonality &Personality = EHPersonality::get(*this);
1377 // This can always be a call because we necessarily didn't find
1378 // anything on the EH stack which needs our help.
1379 const char *RethrowName = Personality.CatchallRethrowFn;
1380 if (RethrowName != nullptr && !isCleanup) {
1381 EmitRuntimeCall(getCatchallRethrowFn(CGM, RethrowName),
1382 getExceptionFromSlot())->setDoesNotReturn();
1383 Builder.CreateUnreachable();
1384 Builder.restoreIP(SavedIP);
1385 return EHResumeBlock;
1388 // Recreate the landingpad's return value for the 'resume' instruction.
1389 llvm::Value *Exn = getExceptionFromSlot();
1390 llvm::Value *Sel = getSelectorFromSlot();
1392 llvm::Type *LPadType = llvm::StructType::get(Exn->getType(), Sel->getType());
1393 llvm::Value *LPadVal = llvm::UndefValue::get(LPadType);
1394 LPadVal = Builder.CreateInsertValue(LPadVal, Exn, 0, "lpad.val");
1395 LPadVal = Builder.CreateInsertValue(LPadVal, Sel, 1, "lpad.val");
1397 Builder.CreateResume(LPadVal);
1398 Builder.restoreIP(SavedIP);
1399 return EHResumeBlock;
1402 void CodeGenFunction::EmitSEHTryStmt(const SEHTryStmt &S) {
1405 JumpDest TryExit = getJumpDestInCurrentScope("__try.__leave");
1407 SEHTryEpilogueStack.push_back(&TryExit);
1408 EmitStmt(S.getTryBlock());
1409 SEHTryEpilogueStack.pop_back();
1411 if (!TryExit.getBlock()->use_empty())
1412 EmitBlock(TryExit.getBlock(), /*IsFinished=*/true);
1414 delete TryExit.getBlock();
1420 struct PerformSEHFinally final : EHScopeStack::Cleanup {
1421 llvm::Function *OutlinedFinally;
1422 PerformSEHFinally(llvm::Function *OutlinedFinally)
1423 : OutlinedFinally(OutlinedFinally) {}
1425 void Emit(CodeGenFunction &CGF, Flags F) override {
1426 ASTContext &Context = CGF.getContext();
1427 CodeGenModule &CGM = CGF.CGM;
1431 // Compute the two argument values.
1432 QualType ArgTys[2] = {Context.UnsignedCharTy, Context.VoidPtrTy};
1433 llvm::Value *LocalAddrFn = CGM.getIntrinsic(llvm::Intrinsic::localaddress);
1434 llvm::Value *FP = CGF.Builder.CreateCall(LocalAddrFn);
1435 llvm::Value *IsForEH =
1436 llvm::ConstantInt::get(CGF.ConvertType(ArgTys[0]), F.isForEHCleanup());
1437 Args.add(RValue::get(IsForEH), ArgTys[0]);
1438 Args.add(RValue::get(FP), ArgTys[1]);
1440 // Arrange a two-arg function info and type.
1441 const CGFunctionInfo &FnInfo =
1442 CGM.getTypes().arrangeBuiltinFunctionCall(Context.VoidTy, Args);
1444 auto Callee = CGCallee::forDirect(OutlinedFinally);
1445 CGF.EmitCall(FnInfo, Callee, ReturnValueSlot(), Args);
1448 } // end anonymous namespace
1451 /// Find all local variable captures in the statement.
1452 struct CaptureFinder : ConstStmtVisitor<CaptureFinder> {
1453 CodeGenFunction &ParentCGF;
1454 const VarDecl *ParentThis;
1455 llvm::SmallSetVector<const VarDecl *, 4> Captures;
1456 Address SEHCodeSlot = Address::invalid();
1457 CaptureFinder(CodeGenFunction &ParentCGF, const VarDecl *ParentThis)
1458 : ParentCGF(ParentCGF), ParentThis(ParentThis) {}
1460 // Return true if we need to do any capturing work.
1461 bool foundCaptures() {
1462 return !Captures.empty() || SEHCodeSlot.isValid();
1465 void Visit(const Stmt *S) {
1466 // See if this is a capture, then recurse.
1467 ConstStmtVisitor<CaptureFinder>::Visit(S);
1468 for (const Stmt *Child : S->children())
1473 void VisitDeclRefExpr(const DeclRefExpr *E) {
1474 // If this is already a capture, just make sure we capture 'this'.
1475 if (E->refersToEnclosingVariableOrCapture()) {
1476 Captures.insert(ParentThis);
1480 const auto *D = dyn_cast<VarDecl>(E->getDecl());
1481 if (D && D->isLocalVarDeclOrParm() && D->hasLocalStorage())
1485 void VisitCXXThisExpr(const CXXThisExpr *E) {
1486 Captures.insert(ParentThis);
1489 void VisitCallExpr(const CallExpr *E) {
1490 // We only need to add parent frame allocations for these builtins in x86.
1491 if (ParentCGF.getTarget().getTriple().getArch() != llvm::Triple::x86)
1494 unsigned ID = E->getBuiltinCallee();
1496 case Builtin::BI__exception_code:
1497 case Builtin::BI_exception_code:
1498 // This is the simple case where we are the outermost finally. All we
1499 // have to do here is make sure we escape this and recover it in the
1500 // outlined handler.
1501 if (!SEHCodeSlot.isValid())
1502 SEHCodeSlot = ParentCGF.SEHCodeSlotStack.back();
1507 } // end anonymous namespace
1509 Address CodeGenFunction::recoverAddrOfEscapedLocal(CodeGenFunction &ParentCGF,
1511 llvm::Value *ParentFP) {
1512 llvm::CallInst *RecoverCall = nullptr;
1513 CGBuilderTy Builder(*this, AllocaInsertPt);
1514 if (auto *ParentAlloca = dyn_cast<llvm::AllocaInst>(ParentVar.getPointer())) {
1515 // Mark the variable escaped if nobody else referenced it and compute the
1516 // localescape index.
1517 auto InsertPair = ParentCGF.EscapedLocals.insert(
1518 std::make_pair(ParentAlloca, ParentCGF.EscapedLocals.size()));
1519 int FrameEscapeIdx = InsertPair.first->second;
1520 // call i8* @llvm.localrecover(i8* bitcast(@parentFn), i8* %fp, i32 N)
1521 llvm::Function *FrameRecoverFn = llvm::Intrinsic::getDeclaration(
1522 &CGM.getModule(), llvm::Intrinsic::localrecover);
1523 llvm::Constant *ParentI8Fn =
1524 llvm::ConstantExpr::getBitCast(ParentCGF.CurFn, Int8PtrTy);
1525 RecoverCall = Builder.CreateCall(
1526 FrameRecoverFn, {ParentI8Fn, ParentFP,
1527 llvm::ConstantInt::get(Int32Ty, FrameEscapeIdx)});
1530 // If the parent didn't have an alloca, we're doing some nested outlining.
1531 // Just clone the existing localrecover call, but tweak the FP argument to
1532 // use our FP value. All other arguments are constants.
1533 auto *ParentRecover =
1534 cast<llvm::IntrinsicInst>(ParentVar.getPointer()->stripPointerCasts());
1535 assert(ParentRecover->getIntrinsicID() == llvm::Intrinsic::localrecover &&
1536 "expected alloca or localrecover in parent LocalDeclMap");
1537 RecoverCall = cast<llvm::CallInst>(ParentRecover->clone());
1538 RecoverCall->setArgOperand(1, ParentFP);
1539 RecoverCall->insertBefore(AllocaInsertPt);
1542 // Bitcast the variable, rename it, and insert it in the local decl map.
1543 llvm::Value *ChildVar =
1544 Builder.CreateBitCast(RecoverCall, ParentVar.getType());
1545 ChildVar->setName(ParentVar.getName());
1546 return Address(ChildVar, ParentVar.getAlignment());
1549 void CodeGenFunction::EmitCapturedLocals(CodeGenFunction &ParentCGF,
1550 const Stmt *OutlinedStmt,
1552 // Find all captures in the Stmt.
1553 CaptureFinder Finder(ParentCGF, ParentCGF.CXXABIThisDecl);
1554 Finder.Visit(OutlinedStmt);
1556 // We can exit early on x86_64 when there are no captures. We just have to
1557 // save the exception code in filters so that __exception_code() works.
1558 if (!Finder.foundCaptures() &&
1559 CGM.getTarget().getTriple().getArch() != llvm::Triple::x86) {
1561 EmitSEHExceptionCodeSave(ParentCGF, nullptr, nullptr);
1565 llvm::Value *EntryFP = nullptr;
1566 CGBuilderTy Builder(CGM, AllocaInsertPt);
1567 if (IsFilter && CGM.getTarget().getTriple().getArch() == llvm::Triple::x86) {
1568 // 32-bit SEH filters need to be careful about FP recovery. The end of the
1569 // EH registration is passed in as the EBP physical register. We can
1570 // recover that with llvm.frameaddress(1).
1571 EntryFP = Builder.CreateCall(
1572 CGM.getIntrinsic(llvm::Intrinsic::frameaddress), {Builder.getInt32(1)});
1574 // Otherwise, for x64 and 32-bit finally functions, the parent FP is the
1575 // second parameter.
1576 auto AI = CurFn->arg_begin();
1581 llvm::Value *ParentFP = EntryFP;
1583 // Given whatever FP the runtime provided us in EntryFP, recover the true
1584 // frame pointer of the parent function. We only need to do this in filters,
1585 // since finally funclets recover the parent FP for us.
1586 llvm::Function *RecoverFPIntrin =
1587 CGM.getIntrinsic(llvm::Intrinsic::x86_seh_recoverfp);
1588 llvm::Constant *ParentI8Fn =
1589 llvm::ConstantExpr::getBitCast(ParentCGF.CurFn, Int8PtrTy);
1590 ParentFP = Builder.CreateCall(RecoverFPIntrin, {ParentI8Fn, EntryFP});
1593 // Create llvm.localrecover calls for all captures.
1594 for (const VarDecl *VD : Finder.Captures) {
1595 if (isa<ImplicitParamDecl>(VD)) {
1596 CGM.ErrorUnsupported(VD, "'this' captured by SEH");
1597 CXXThisValue = llvm::UndefValue::get(ConvertTypeForMem(VD->getType()));
1600 if (VD->getType()->isVariablyModifiedType()) {
1601 CGM.ErrorUnsupported(VD, "VLA captured by SEH");
1604 assert((isa<ImplicitParamDecl>(VD) || VD->isLocalVarDeclOrParm()) &&
1605 "captured non-local variable");
1607 // If this decl hasn't been declared yet, it will be declared in the
1609 auto I = ParentCGF.LocalDeclMap.find(VD);
1610 if (I == ParentCGF.LocalDeclMap.end())
1613 Address ParentVar = I->second;
1615 VD, recoverAddrOfEscapedLocal(ParentCGF, ParentVar, ParentFP));
1618 if (Finder.SEHCodeSlot.isValid()) {
1619 SEHCodeSlotStack.push_back(
1620 recoverAddrOfEscapedLocal(ParentCGF, Finder.SEHCodeSlot, ParentFP));
1624 EmitSEHExceptionCodeSave(ParentCGF, ParentFP, EntryFP);
1627 /// Arrange a function prototype that can be called by Windows exception
1628 /// handling personalities. On Win64, the prototype looks like:
1629 /// RetTy func(void *EHPtrs, void *ParentFP);
1630 void CodeGenFunction::startOutlinedSEHHelper(CodeGenFunction &ParentCGF,
1632 const Stmt *OutlinedStmt) {
1633 SourceLocation StartLoc = OutlinedStmt->getLocStart();
1635 // Get the mangled function name.
1636 SmallString<128> Name;
1638 llvm::raw_svector_ostream OS(Name);
1639 const FunctionDecl *ParentSEHFn = ParentCGF.CurSEHParent;
1640 assert(ParentSEHFn && "No CurSEHParent!");
1641 MangleContext &Mangler = CGM.getCXXABI().getMangleContext();
1643 Mangler.mangleSEHFilterExpression(ParentSEHFn, OS);
1645 Mangler.mangleSEHFinallyBlock(ParentSEHFn, OS);
1648 FunctionArgList Args;
1649 if (CGM.getTarget().getTriple().getArch() != llvm::Triple::x86 || !IsFilter) {
1650 // All SEH finally functions take two parameters. Win64 filters take two
1651 // parameters. Win32 filters take no parameters.
1653 Args.push_back(ImplicitParamDecl::Create(
1654 getContext(), /*DC=*/nullptr, StartLoc,
1655 &getContext().Idents.get("exception_pointers"),
1656 getContext().VoidPtrTy, ImplicitParamDecl::Other));
1658 Args.push_back(ImplicitParamDecl::Create(
1659 getContext(), /*DC=*/nullptr, StartLoc,
1660 &getContext().Idents.get("abnormal_termination"),
1661 getContext().UnsignedCharTy, ImplicitParamDecl::Other));
1663 Args.push_back(ImplicitParamDecl::Create(
1664 getContext(), /*DC=*/nullptr, StartLoc,
1665 &getContext().Idents.get("frame_pointer"), getContext().VoidPtrTy,
1666 ImplicitParamDecl::Other));
1669 QualType RetTy = IsFilter ? getContext().LongTy : getContext().VoidTy;
1671 const CGFunctionInfo &FnInfo =
1672 CGM.getTypes().arrangeBuiltinFunctionDeclaration(RetTy, Args);
1674 llvm::FunctionType *FnTy = CGM.getTypes().GetFunctionType(FnInfo);
1675 llvm::Function *Fn = llvm::Function::Create(
1676 FnTy, llvm::GlobalValue::InternalLinkage, Name.str(), &CGM.getModule());
1678 IsOutlinedSEHHelper = true;
1680 StartFunction(GlobalDecl(), RetTy, Fn, FnInfo, Args,
1681 OutlinedStmt->getLocStart(), OutlinedStmt->getLocStart());
1682 CurSEHParent = ParentCGF.CurSEHParent;
1684 CGM.SetLLVMFunctionAttributes(nullptr, FnInfo, CurFn);
1685 EmitCapturedLocals(ParentCGF, OutlinedStmt, IsFilter);
1688 /// Create a stub filter function that will ultimately hold the code of the
1689 /// filter expression. The EH preparation passes in LLVM will outline the code
1690 /// from the main function body into this stub.
1692 CodeGenFunction::GenerateSEHFilterFunction(CodeGenFunction &ParentCGF,
1693 const SEHExceptStmt &Except) {
1694 const Expr *FilterExpr = Except.getFilterExpr();
1695 startOutlinedSEHHelper(ParentCGF, true, FilterExpr);
1697 // Emit the original filter expression, convert to i32, and return.
1698 llvm::Value *R = EmitScalarExpr(FilterExpr);
1699 R = Builder.CreateIntCast(R, ConvertType(getContext().LongTy),
1700 FilterExpr->getType()->isSignedIntegerType());
1701 Builder.CreateStore(R, ReturnValue);
1703 FinishFunction(FilterExpr->getLocEnd());
1709 CodeGenFunction::GenerateSEHFinallyFunction(CodeGenFunction &ParentCGF,
1710 const SEHFinallyStmt &Finally) {
1711 const Stmt *FinallyBlock = Finally.getBlock();
1712 startOutlinedSEHHelper(ParentCGF, false, FinallyBlock);
1714 // Emit the original filter expression, convert to i32, and return.
1715 EmitStmt(FinallyBlock);
1717 FinishFunction(FinallyBlock->getLocEnd());
1722 void CodeGenFunction::EmitSEHExceptionCodeSave(CodeGenFunction &ParentCGF,
1723 llvm::Value *ParentFP,
1724 llvm::Value *EntryFP) {
1725 // Get the pointer to the EXCEPTION_POINTERS struct. This is returned by the
1726 // __exception_info intrinsic.
1727 if (CGM.getTarget().getTriple().getArch() != llvm::Triple::x86) {
1728 // On Win64, the info is passed as the first parameter to the filter.
1729 SEHInfo = &*CurFn->arg_begin();
1730 SEHCodeSlotStack.push_back(
1731 CreateMemTemp(getContext().IntTy, "__exception_code"));
1733 // On Win32, the EBP on entry to the filter points to the end of an
1734 // exception registration object. It contains 6 32-bit fields, and the info
1735 // pointer is stored in the second field. So, GEP 20 bytes backwards and
1736 // load the pointer.
1737 SEHInfo = Builder.CreateConstInBoundsGEP1_32(Int8Ty, EntryFP, -20);
1738 SEHInfo = Builder.CreateBitCast(SEHInfo, Int8PtrTy->getPointerTo());
1739 SEHInfo = Builder.CreateAlignedLoad(Int8PtrTy, SEHInfo, getPointerAlign());
1740 SEHCodeSlotStack.push_back(recoverAddrOfEscapedLocal(
1741 ParentCGF, ParentCGF.SEHCodeSlotStack.back(), ParentFP));
1744 // Save the exception code in the exception slot to unify exception access in
1745 // the filter function and the landing pad.
1746 // struct EXCEPTION_POINTERS {
1747 // EXCEPTION_RECORD *ExceptionRecord;
1748 // CONTEXT *ContextRecord;
1750 // int exceptioncode = exception_pointers->ExceptionRecord->ExceptionCode;
1751 llvm::Type *RecordTy = CGM.Int32Ty->getPointerTo();
1752 llvm::Type *PtrsTy = llvm::StructType::get(RecordTy, CGM.VoidPtrTy);
1753 llvm::Value *Ptrs = Builder.CreateBitCast(SEHInfo, PtrsTy->getPointerTo());
1754 llvm::Value *Rec = Builder.CreateStructGEP(PtrsTy, Ptrs, 0);
1755 Rec = Builder.CreateAlignedLoad(Rec, getPointerAlign());
1756 llvm::Value *Code = Builder.CreateAlignedLoad(Rec, getIntAlign());
1757 assert(!SEHCodeSlotStack.empty() && "emitting EH code outside of __except");
1758 Builder.CreateStore(Code, SEHCodeSlotStack.back());
1761 llvm::Value *CodeGenFunction::EmitSEHExceptionInfo() {
1762 // Sema should diagnose calling this builtin outside of a filter context, but
1763 // don't crash if we screw up.
1765 return llvm::UndefValue::get(Int8PtrTy);
1766 assert(SEHInfo->getType() == Int8PtrTy);
1770 llvm::Value *CodeGenFunction::EmitSEHExceptionCode() {
1771 assert(!SEHCodeSlotStack.empty() && "emitting EH code outside of __except");
1772 return Builder.CreateLoad(SEHCodeSlotStack.back());
1775 llvm::Value *CodeGenFunction::EmitSEHAbnormalTermination() {
1776 // Abnormal termination is just the first parameter to the outlined finally
1778 auto AI = CurFn->arg_begin();
1779 return Builder.CreateZExt(&*AI, Int32Ty);
1782 void CodeGenFunction::EnterSEHTryStmt(const SEHTryStmt &S) {
1783 CodeGenFunction HelperCGF(CGM, /*suppressNewContext=*/true);
1784 if (const SEHFinallyStmt *Finally = S.getFinallyHandler()) {
1785 // Outline the finally block.
1786 llvm::Function *FinallyFunc =
1787 HelperCGF.GenerateSEHFinallyFunction(*this, *Finally);
1789 // Push a cleanup for __finally blocks.
1790 EHStack.pushCleanup<PerformSEHFinally>(NormalAndEHCleanup, FinallyFunc);
1794 // Otherwise, we must have an __except block.
1795 const SEHExceptStmt *Except = S.getExceptHandler();
1797 EHCatchScope *CatchScope = EHStack.pushCatch(1);
1798 SEHCodeSlotStack.push_back(
1799 CreateMemTemp(getContext().IntTy, "__exception_code"));
1801 // If the filter is known to evaluate to 1, then we can use the clause
1802 // "catch i8* null". We can't do this on x86 because the filter has to save
1803 // the exception code.
1805 ConstantEmitter(*this).tryEmitAbstract(Except->getFilterExpr(),
1806 getContext().IntTy);
1807 if (CGM.getTarget().getTriple().getArch() != llvm::Triple::x86 && C &&
1809 CatchScope->setCatchAllHandler(0, createBasicBlock("__except"));
1813 // In general, we have to emit an outlined filter function. Use the function
1814 // in place of the RTTI typeinfo global that C++ EH uses.
1815 llvm::Function *FilterFunc =
1816 HelperCGF.GenerateSEHFilterFunction(*this, *Except);
1817 llvm::Constant *OpaqueFunc =
1818 llvm::ConstantExpr::getBitCast(FilterFunc, Int8PtrTy);
1819 CatchScope->setHandler(0, OpaqueFunc, createBasicBlock("__except.ret"));
1822 void CodeGenFunction::ExitSEHTryStmt(const SEHTryStmt &S) {
1823 // Just pop the cleanup if it's a __finally block.
1824 if (S.getFinallyHandler()) {
1829 // Otherwise, we must have an __except block.
1830 const SEHExceptStmt *Except = S.getExceptHandler();
1831 assert(Except && "__try must have __finally xor __except");
1832 EHCatchScope &CatchScope = cast<EHCatchScope>(*EHStack.begin());
1834 // Don't emit the __except block if the __try block lacked invokes.
1835 // TODO: Model unwind edges from instructions, either with iload / istore or
1836 // a try body function.
1837 if (!CatchScope.hasEHBranches()) {
1838 CatchScope.clearHandlerBlocks();
1840 SEHCodeSlotStack.pop_back();
1844 // The fall-through block.
1845 llvm::BasicBlock *ContBB = createBasicBlock("__try.cont");
1847 // We just emitted the body of the __try; jump to the continue block.
1848 if (HaveInsertPoint())
1849 Builder.CreateBr(ContBB);
1851 // Check if our filter function returned true.
1852 emitCatchDispatchBlock(*this, CatchScope);
1854 // Grab the block before we pop the handler.
1855 llvm::BasicBlock *CatchPadBB = CatchScope.getHandler(0).Block;
1858 EmitBlockAfterUses(CatchPadBB);
1860 // __except blocks don't get outlined into funclets, so immediately do a
1862 llvm::CatchPadInst *CPI =
1863 cast<llvm::CatchPadInst>(CatchPadBB->getFirstNonPHI());
1864 llvm::BasicBlock *ExceptBB = createBasicBlock("__except");
1865 Builder.CreateCatchRet(CPI, ExceptBB);
1866 EmitBlock(ExceptBB);
1868 // On Win64, the exception code is returned in EAX. Copy it into the slot.
1869 if (CGM.getTarget().getTriple().getArch() != llvm::Triple::x86) {
1870 llvm::Function *SEHCodeIntrin =
1871 CGM.getIntrinsic(llvm::Intrinsic::eh_exceptioncode);
1872 llvm::Value *Code = Builder.CreateCall(SEHCodeIntrin, {CPI});
1873 Builder.CreateStore(Code, SEHCodeSlotStack.back());
1876 // Emit the __except body.
1877 EmitStmt(Except->getBlock());
1879 // End the lifetime of the exception code.
1880 SEHCodeSlotStack.pop_back();
1882 if (HaveInsertPoint())
1883 Builder.CreateBr(ContBB);
1888 void CodeGenFunction::EmitSEHLeaveStmt(const SEHLeaveStmt &S) {
1889 // If this code is reachable then emit a stop point (if generating
1890 // debug info). We have to do this ourselves because we are on the
1891 // "simple" statement path.
1892 if (HaveInsertPoint())
1895 // This must be a __leave from a __finally block, which we warn on and is UB.
1896 // Just emit unreachable.
1897 if (!isSEHTryScope()) {
1898 Builder.CreateUnreachable();
1899 Builder.ClearInsertionPoint();
1903 EmitBranchThroughCleanup(*SEHTryEpilogueStack.back());