1 //===--- CGException.cpp - Emit LLVM Code for C++ exceptions ----*- C++ -*-===//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
9 // This contains code dealing with C++ exception related code generation.
11 //===----------------------------------------------------------------------===//
13 #include "CodeGenFunction.h"
15 #include "CGCleanup.h"
16 #include "CGObjCRuntime.h"
17 #include "ConstantEmitter.h"
18 #include "TargetInfo.h"
19 #include "clang/AST/Mangle.h"
20 #include "clang/AST/StmtCXX.h"
21 #include "clang/AST/StmtObjC.h"
22 #include "clang/AST/StmtVisitor.h"
23 #include "clang/Basic/TargetBuiltins.h"
24 #include "llvm/IR/Intrinsics.h"
25 #include "llvm/IR/IntrinsicInst.h"
26 #include "llvm/Support/SaveAndRestore.h"
28 using namespace clang;
29 using namespace CodeGen;
31 static llvm::FunctionCallee getFreeExceptionFn(CodeGenModule &CGM) {
32 // void __cxa_free_exception(void *thrown_exception);
34 llvm::FunctionType *FTy =
35 llvm::FunctionType::get(CGM.VoidTy, CGM.Int8PtrTy, /*isVarArg=*/false);
37 return CGM.CreateRuntimeFunction(FTy, "__cxa_free_exception");
40 static llvm::FunctionCallee getUnexpectedFn(CodeGenModule &CGM) {
41 // void __cxa_call_unexpected(void *thrown_exception);
43 llvm::FunctionType *FTy =
44 llvm::FunctionType::get(CGM.VoidTy, CGM.Int8PtrTy, /*isVarArg=*/false);
46 return CGM.CreateRuntimeFunction(FTy, "__cxa_call_unexpected");
49 llvm::FunctionCallee CodeGenModule::getTerminateFn() {
50 // void __terminate();
52 llvm::FunctionType *FTy =
53 llvm::FunctionType::get(VoidTy, /*isVarArg=*/false);
57 // In C++, use std::terminate().
58 if (getLangOpts().CPlusPlus &&
59 getTarget().getCXXABI().isItaniumFamily()) {
60 name = "_ZSt9terminatev";
61 } else if (getLangOpts().CPlusPlus &&
62 getTarget().getCXXABI().isMicrosoft()) {
63 if (getLangOpts().isCompatibleWithMSVC(LangOptions::MSVC2015))
64 name = "__std_terminate";
66 name = "?terminate@@YAXXZ";
67 } else if (getLangOpts().ObjC &&
68 getLangOpts().ObjCRuntime.hasTerminate())
69 name = "objc_terminate";
72 return CreateRuntimeFunction(FTy, name);
75 static llvm::FunctionCallee getCatchallRethrowFn(CodeGenModule &CGM,
77 llvm::FunctionType *FTy =
78 llvm::FunctionType::get(CGM.VoidTy, CGM.Int8PtrTy, /*isVarArg=*/false);
80 return CGM.CreateRuntimeFunction(FTy, Name);
83 const EHPersonality EHPersonality::GNU_C = { "__gcc_personality_v0", nullptr };
85 EHPersonality::GNU_C_SJLJ = { "__gcc_personality_sj0", nullptr };
87 EHPersonality::GNU_C_SEH = { "__gcc_personality_seh0", nullptr };
89 EHPersonality::NeXT_ObjC = { "__objc_personality_v0", nullptr };
91 EHPersonality::GNU_CPlusPlus = { "__gxx_personality_v0", nullptr };
93 EHPersonality::GNU_CPlusPlus_SJLJ = { "__gxx_personality_sj0", nullptr };
95 EHPersonality::GNU_CPlusPlus_SEH = { "__gxx_personality_seh0", nullptr };
97 EHPersonality::GNU_ObjC = {"__gnu_objc_personality_v0", "objc_exception_throw"};
99 EHPersonality::GNU_ObjC_SJLJ = {"__gnu_objc_personality_sj0", "objc_exception_throw"};
101 EHPersonality::GNU_ObjC_SEH = {"__gnu_objc_personality_seh0", "objc_exception_throw"};
103 EHPersonality::GNU_ObjCXX = { "__gnustep_objcxx_personality_v0", nullptr };
105 EHPersonality::GNUstep_ObjC = { "__gnustep_objc_personality_v0", nullptr };
107 EHPersonality::MSVC_except_handler = { "_except_handler3", nullptr };
109 EHPersonality::MSVC_C_specific_handler = { "__C_specific_handler", nullptr };
111 EHPersonality::MSVC_CxxFrameHandler3 = { "__CxxFrameHandler3", nullptr };
113 EHPersonality::GNU_Wasm_CPlusPlus = { "__gxx_wasm_personality_v0", nullptr };
115 static const EHPersonality &getCPersonality(const TargetInfo &Target,
116 const LangOptions &L) {
117 const llvm::Triple &T = Target.getTriple();
118 if (T.isWindowsMSVCEnvironment())
119 return EHPersonality::MSVC_CxxFrameHandler3;
120 if (L.SjLjExceptions)
121 return EHPersonality::GNU_C_SJLJ;
122 if (L.DWARFExceptions)
123 return EHPersonality::GNU_C;
125 return EHPersonality::GNU_C_SEH;
126 return EHPersonality::GNU_C;
129 static const EHPersonality &getObjCPersonality(const TargetInfo &Target,
130 const LangOptions &L) {
131 const llvm::Triple &T = Target.getTriple();
132 if (T.isWindowsMSVCEnvironment())
133 return EHPersonality::MSVC_CxxFrameHandler3;
135 switch (L.ObjCRuntime.getKind()) {
136 case ObjCRuntime::FragileMacOSX:
137 return getCPersonality(Target, L);
138 case ObjCRuntime::MacOSX:
139 case ObjCRuntime::iOS:
140 case ObjCRuntime::WatchOS:
141 return EHPersonality::NeXT_ObjC;
142 case ObjCRuntime::GNUstep:
143 if (L.ObjCRuntime.getVersion() >= VersionTuple(1, 7))
144 return EHPersonality::GNUstep_ObjC;
146 case ObjCRuntime::GCC:
147 case ObjCRuntime::ObjFW:
148 if (L.SjLjExceptions)
149 return EHPersonality::GNU_ObjC_SJLJ;
151 return EHPersonality::GNU_ObjC_SEH;
152 return EHPersonality::GNU_ObjC;
154 llvm_unreachable("bad runtime kind");
157 static const EHPersonality &getCXXPersonality(const TargetInfo &Target,
158 const LangOptions &L) {
159 const llvm::Triple &T = Target.getTriple();
160 if (T.isWindowsMSVCEnvironment())
161 return EHPersonality::MSVC_CxxFrameHandler3;
162 if (L.SjLjExceptions)
163 return EHPersonality::GNU_CPlusPlus_SJLJ;
164 if (L.DWARFExceptions)
165 return EHPersonality::GNU_CPlusPlus;
167 return EHPersonality::GNU_CPlusPlus_SEH;
168 // Wasm EH is a non-MVP feature for now.
169 if (Target.hasFeature("exception-handling") &&
170 (T.getArch() == llvm::Triple::wasm32 ||
171 T.getArch() == llvm::Triple::wasm64))
172 return EHPersonality::GNU_Wasm_CPlusPlus;
173 return EHPersonality::GNU_CPlusPlus;
176 /// Determines the personality function to use when both C++
177 /// and Objective-C exceptions are being caught.
178 static const EHPersonality &getObjCXXPersonality(const TargetInfo &Target,
179 const LangOptions &L) {
180 if (Target.getTriple().isWindowsMSVCEnvironment())
181 return EHPersonality::MSVC_CxxFrameHandler3;
183 switch (L.ObjCRuntime.getKind()) {
184 // In the fragile ABI, just use C++ exception handling and hope
185 // they're not doing crazy exception mixing.
186 case ObjCRuntime::FragileMacOSX:
187 return getCXXPersonality(Target, L);
189 // The ObjC personality defers to the C++ personality for non-ObjC
190 // handlers. Unlike the C++ case, we use the same personality
191 // function on targets using (backend-driven) SJLJ EH.
192 case ObjCRuntime::MacOSX:
193 case ObjCRuntime::iOS:
194 case ObjCRuntime::WatchOS:
195 return getObjCPersonality(Target, L);
197 case ObjCRuntime::GNUstep:
198 return EHPersonality::GNU_ObjCXX;
200 // The GCC runtime's personality function inherently doesn't support
201 // mixed EH. Use the ObjC personality just to avoid returning null.
202 case ObjCRuntime::GCC:
203 case ObjCRuntime::ObjFW:
204 return getObjCPersonality(Target, L);
206 llvm_unreachable("bad runtime kind");
209 static const EHPersonality &getSEHPersonalityMSVC(const llvm::Triple &T) {
210 if (T.getArch() == llvm::Triple::x86)
211 return EHPersonality::MSVC_except_handler;
212 return EHPersonality::MSVC_C_specific_handler;
215 const EHPersonality &EHPersonality::get(CodeGenModule &CGM,
216 const FunctionDecl *FD) {
217 const llvm::Triple &T = CGM.getTarget().getTriple();
218 const LangOptions &L = CGM.getLangOpts();
219 const TargetInfo &Target = CGM.getTarget();
221 // Functions using SEH get an SEH personality.
222 if (FD && FD->usesSEHTry())
223 return getSEHPersonalityMSVC(T);
226 return L.CPlusPlus ? getObjCXXPersonality(Target, L)
227 : getObjCPersonality(Target, L);
228 return L.CPlusPlus ? getCXXPersonality(Target, L)
229 : getCPersonality(Target, L);
232 const EHPersonality &EHPersonality::get(CodeGenFunction &CGF) {
233 const auto *FD = CGF.CurCodeDecl;
234 // For outlined finallys and filters, use the SEH personality in case they
235 // contain more SEH. This mostly only affects finallys. Filters could
236 // hypothetically use gnu statement expressions to sneak in nested SEH.
237 FD = FD ? FD : CGF.CurSEHParent;
238 return get(CGF.CGM, dyn_cast_or_null<FunctionDecl>(FD));
241 static llvm::FunctionCallee getPersonalityFn(CodeGenModule &CGM,
242 const EHPersonality &Personality) {
243 return CGM.CreateRuntimeFunction(llvm::FunctionType::get(CGM.Int32Ty, true),
244 Personality.PersonalityFn,
245 llvm::AttributeList(), /*Local=*/true);
248 static llvm::Constant *getOpaquePersonalityFn(CodeGenModule &CGM,
249 const EHPersonality &Personality) {
250 llvm::FunctionCallee Fn = getPersonalityFn(CGM, Personality);
251 llvm::PointerType* Int8PtrTy = llvm::PointerType::get(
252 llvm::Type::getInt8Ty(CGM.getLLVMContext()),
253 CGM.getDataLayout().getProgramAddressSpace());
255 return llvm::ConstantExpr::getBitCast(cast<llvm::Constant>(Fn.getCallee()),
259 /// Check whether a landingpad instruction only uses C++ features.
260 static bool LandingPadHasOnlyCXXUses(llvm::LandingPadInst *LPI) {
261 for (unsigned I = 0, E = LPI->getNumClauses(); I != E; ++I) {
262 // Look for something that would've been returned by the ObjC
263 // runtime's GetEHType() method.
264 llvm::Value *Val = LPI->getClause(I)->stripPointerCasts();
265 if (LPI->isCatch(I)) {
266 // Check if the catch value has the ObjC prefix.
267 if (llvm::GlobalVariable *GV = dyn_cast<llvm::GlobalVariable>(Val))
268 // ObjC EH selector entries are always global variables with
269 // names starting like this.
270 if (GV->getName().startswith("OBJC_EHTYPE"))
273 // Check if any of the filter values have the ObjC prefix.
274 llvm::Constant *CVal = cast<llvm::Constant>(Val);
275 for (llvm::User::op_iterator
276 II = CVal->op_begin(), IE = CVal->op_end(); II != IE; ++II) {
277 if (llvm::GlobalVariable *GV =
278 cast<llvm::GlobalVariable>((*II)->stripPointerCasts()))
279 // ObjC EH selector entries are always global variables with
280 // names starting like this.
281 if (GV->getName().startswith("OBJC_EHTYPE"))
289 /// Check whether a personality function could reasonably be swapped
290 /// for a C++ personality function.
291 static bool PersonalityHasOnlyCXXUses(llvm::Constant *Fn) {
292 for (llvm::User *U : Fn->users()) {
293 // Conditionally white-list bitcasts.
294 if (llvm::ConstantExpr *CE = dyn_cast<llvm::ConstantExpr>(U)) {
295 if (CE->getOpcode() != llvm::Instruction::BitCast) return false;
296 if (!PersonalityHasOnlyCXXUses(CE))
301 // Otherwise it must be a function.
302 llvm::Function *F = dyn_cast<llvm::Function>(U);
303 if (!F) return false;
305 for (auto BB = F->begin(), E = F->end(); BB != E; ++BB) {
306 if (BB->isLandingPad())
307 if (!LandingPadHasOnlyCXXUses(BB->getLandingPadInst()))
315 /// Try to use the C++ personality function in ObjC++. Not doing this
316 /// can cause some incompatibilities with gcc, which is more
317 /// aggressive about only using the ObjC++ personality in a function
318 /// when it really needs it.
319 void CodeGenModule::SimplifyPersonality() {
320 // If we're not in ObjC++ -fexceptions, there's nothing to do.
321 if (!LangOpts.CPlusPlus || !LangOpts.ObjC || !LangOpts.Exceptions)
324 // Both the problem this endeavors to fix and the way the logic
325 // above works is specific to the NeXT runtime.
326 if (!LangOpts.ObjCRuntime.isNeXTFamily())
329 const EHPersonality &ObjCXX = EHPersonality::get(*this, /*FD=*/nullptr);
330 const EHPersonality &CXX = getCXXPersonality(getTarget(), LangOpts);
334 assert(std::strcmp(ObjCXX.PersonalityFn, CXX.PersonalityFn) != 0 &&
335 "Different EHPersonalities using the same personality function.");
337 llvm::Function *Fn = getModule().getFunction(ObjCXX.PersonalityFn);
339 // Nothing to do if it's unused.
340 if (!Fn || Fn->use_empty()) return;
342 // Can't do the optimization if it has non-C++ uses.
343 if (!PersonalityHasOnlyCXXUses(Fn)) return;
345 // Create the C++ personality function and kill off the old
347 llvm::FunctionCallee CXXFn = getPersonalityFn(*this, CXX);
349 // This can happen if the user is screwing with us.
350 if (Fn->getType() != CXXFn.getCallee()->getType())
353 Fn->replaceAllUsesWith(CXXFn.getCallee());
354 Fn->eraseFromParent();
357 /// Returns the value to inject into a selector to indicate the
358 /// presence of a catch-all.
359 static llvm::Constant *getCatchAllValue(CodeGenFunction &CGF) {
360 // Possibly we should use @llvm.eh.catch.all.value here.
361 return llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
365 /// A cleanup to free the exception object if its initialization
367 struct FreeException final : EHScopeStack::Cleanup {
369 FreeException(llvm::Value *exn) : exn(exn) {}
370 void Emit(CodeGenFunction &CGF, Flags flags) override {
371 CGF.EmitNounwindRuntimeCall(getFreeExceptionFn(CGF.CGM), exn);
374 } // end anonymous namespace
376 // Emits an exception expression into the given location. This
377 // differs from EmitAnyExprToMem only in that, if a final copy-ctor
378 // call is required, an exception within that copy ctor causes
379 // std::terminate to be invoked.
380 void CodeGenFunction::EmitAnyExprToExn(const Expr *e, Address addr) {
381 // Make sure the exception object is cleaned up if there's an
382 // exception during initialization.
383 pushFullExprCleanup<FreeException>(EHCleanup, addr.getPointer());
384 EHScopeStack::stable_iterator cleanup = EHStack.stable_begin();
386 // __cxa_allocate_exception returns a void*; we need to cast this
387 // to the appropriate type for the object.
388 llvm::Type *ty = ConvertTypeForMem(e->getType())->getPointerTo();
389 Address typedAddr = Builder.CreateBitCast(addr, ty);
391 // FIXME: this isn't quite right! If there's a final unelided call
392 // to a copy constructor, then according to [except.terminate]p1 we
393 // must call std::terminate() if that constructor throws, because
394 // technically that copy occurs after the exception expression is
395 // evaluated but before the exception is caught. But the best way
396 // to handle that is to teach EmitAggExpr to do the final copy
397 // differently if it can't be elided.
398 EmitAnyExprToMem(e, typedAddr, e->getType().getQualifiers(),
401 // Deactivate the cleanup block.
402 DeactivateCleanupBlock(cleanup,
403 cast<llvm::Instruction>(typedAddr.getPointer()));
406 Address CodeGenFunction::getExceptionSlot() {
408 ExceptionSlot = CreateTempAlloca(Int8PtrTy, "exn.slot");
409 return Address(ExceptionSlot, getPointerAlign());
412 Address CodeGenFunction::getEHSelectorSlot() {
414 EHSelectorSlot = CreateTempAlloca(Int32Ty, "ehselector.slot");
415 return Address(EHSelectorSlot, CharUnits::fromQuantity(4));
418 llvm::Value *CodeGenFunction::getExceptionFromSlot() {
419 return Builder.CreateLoad(getExceptionSlot(), "exn");
422 llvm::Value *CodeGenFunction::getSelectorFromSlot() {
423 return Builder.CreateLoad(getEHSelectorSlot(), "sel");
426 void CodeGenFunction::EmitCXXThrowExpr(const CXXThrowExpr *E,
427 bool KeepInsertionPoint) {
428 if (const Expr *SubExpr = E->getSubExpr()) {
429 QualType ThrowType = SubExpr->getType();
430 if (ThrowType->isObjCObjectPointerType()) {
431 const Stmt *ThrowStmt = E->getSubExpr();
432 const ObjCAtThrowStmt S(E->getExprLoc(), const_cast<Stmt *>(ThrowStmt));
433 CGM.getObjCRuntime().EmitThrowStmt(*this, S, false);
435 CGM.getCXXABI().emitThrow(*this, E);
438 CGM.getCXXABI().emitRethrow(*this, /*isNoReturn=*/true);
441 // throw is an expression, and the expression emitters expect us
442 // to leave ourselves at a valid insertion point.
443 if (KeepInsertionPoint)
444 EmitBlock(createBasicBlock("throw.cont"));
447 void CodeGenFunction::EmitStartEHSpec(const Decl *D) {
448 if (!CGM.getLangOpts().CXXExceptions)
451 const FunctionDecl* FD = dyn_cast_or_null<FunctionDecl>(D);
453 // Check if CapturedDecl is nothrow and create terminate scope for it.
454 if (const CapturedDecl* CD = dyn_cast_or_null<CapturedDecl>(D)) {
456 EHStack.pushTerminate();
460 const FunctionProtoType *Proto = FD->getType()->getAs<FunctionProtoType>();
464 ExceptionSpecificationType EST = Proto->getExceptionSpecType();
465 if (isNoexceptExceptionSpec(EST) && Proto->canThrow() == CT_Cannot) {
466 // noexcept functions are simple terminate scopes.
467 EHStack.pushTerminate();
468 } else if (EST == EST_Dynamic || EST == EST_DynamicNone) {
469 // TODO: Revisit exception specifications for the MS ABI. There is a way to
470 // encode these in an object file but MSVC doesn't do anything with it.
471 if (getTarget().getCXXABI().isMicrosoft())
473 unsigned NumExceptions = Proto->getNumExceptions();
474 EHFilterScope *Filter = EHStack.pushFilter(NumExceptions);
476 for (unsigned I = 0; I != NumExceptions; ++I) {
477 QualType Ty = Proto->getExceptionType(I);
478 QualType ExceptType = Ty.getNonReferenceType().getUnqualifiedType();
479 llvm::Value *EHType = CGM.GetAddrOfRTTIDescriptor(ExceptType,
481 Filter->setFilter(I, EHType);
486 /// Emit the dispatch block for a filter scope if necessary.
487 static void emitFilterDispatchBlock(CodeGenFunction &CGF,
488 EHFilterScope &filterScope) {
489 llvm::BasicBlock *dispatchBlock = filterScope.getCachedEHDispatchBlock();
490 if (!dispatchBlock) return;
491 if (dispatchBlock->use_empty()) {
492 delete dispatchBlock;
496 CGF.EmitBlockAfterUses(dispatchBlock);
498 // If this isn't a catch-all filter, we need to check whether we got
499 // here because the filter triggered.
500 if (filterScope.getNumFilters()) {
501 // Load the selector value.
502 llvm::Value *selector = CGF.getSelectorFromSlot();
503 llvm::BasicBlock *unexpectedBB = CGF.createBasicBlock("ehspec.unexpected");
505 llvm::Value *zero = CGF.Builder.getInt32(0);
506 llvm::Value *failsFilter =
507 CGF.Builder.CreateICmpSLT(selector, zero, "ehspec.fails");
508 CGF.Builder.CreateCondBr(failsFilter, unexpectedBB,
509 CGF.getEHResumeBlock(false));
511 CGF.EmitBlock(unexpectedBB);
514 // Call __cxa_call_unexpected. This doesn't need to be an invoke
515 // because __cxa_call_unexpected magically filters exceptions
516 // according to the last landing pad the exception was thrown
518 llvm::Value *exn = CGF.getExceptionFromSlot();
519 CGF.EmitRuntimeCall(getUnexpectedFn(CGF.CGM), exn)
520 ->setDoesNotReturn();
521 CGF.Builder.CreateUnreachable();
524 void CodeGenFunction::EmitEndEHSpec(const Decl *D) {
525 if (!CGM.getLangOpts().CXXExceptions)
528 const FunctionDecl* FD = dyn_cast_or_null<FunctionDecl>(D);
530 // Check if CapturedDecl is nothrow and pop terminate scope for it.
531 if (const CapturedDecl* CD = dyn_cast_or_null<CapturedDecl>(D)) {
533 EHStack.popTerminate();
537 const FunctionProtoType *Proto = FD->getType()->getAs<FunctionProtoType>();
541 ExceptionSpecificationType EST = Proto->getExceptionSpecType();
542 if (isNoexceptExceptionSpec(EST) && Proto->canThrow() == CT_Cannot) {
543 EHStack.popTerminate();
544 } else if (EST == EST_Dynamic || EST == EST_DynamicNone) {
545 // TODO: Revisit exception specifications for the MS ABI. There is a way to
546 // encode these in an object file but MSVC doesn't do anything with it.
547 if (getTarget().getCXXABI().isMicrosoft())
549 EHFilterScope &filterScope = cast<EHFilterScope>(*EHStack.begin());
550 emitFilterDispatchBlock(*this, filterScope);
555 void CodeGenFunction::EmitCXXTryStmt(const CXXTryStmt &S) {
557 EmitStmt(S.getTryBlock());
561 void CodeGenFunction::EnterCXXTryStmt(const CXXTryStmt &S, bool IsFnTryBlock) {
562 unsigned NumHandlers = S.getNumHandlers();
563 EHCatchScope *CatchScope = EHStack.pushCatch(NumHandlers);
565 for (unsigned I = 0; I != NumHandlers; ++I) {
566 const CXXCatchStmt *C = S.getHandler(I);
568 llvm::BasicBlock *Handler = createBasicBlock("catch");
569 if (C->getExceptionDecl()) {
570 // FIXME: Dropping the reference type on the type into makes it
571 // impossible to correctly implement catch-by-reference
572 // semantics for pointers. Unfortunately, this is what all
573 // existing compilers do, and it's not clear that the standard
574 // personality routine is capable of doing this right. See C++ DR 388:
575 // http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#388
576 Qualifiers CaughtTypeQuals;
577 QualType CaughtType = CGM.getContext().getUnqualifiedArrayType(
578 C->getCaughtType().getNonReferenceType(), CaughtTypeQuals);
580 CatchTypeInfo TypeInfo{nullptr, 0};
581 if (CaughtType->isObjCObjectPointerType())
582 TypeInfo.RTTI = CGM.getObjCRuntime().GetEHType(CaughtType);
584 TypeInfo = CGM.getCXXABI().getAddrOfCXXCatchHandlerType(
585 CaughtType, C->getCaughtType());
586 CatchScope->setHandler(I, TypeInfo, Handler);
588 // No exception decl indicates '...', a catch-all.
589 CatchScope->setHandler(I, CGM.getCXXABI().getCatchAllTypeInfo(), Handler);
595 CodeGenFunction::getEHDispatchBlock(EHScopeStack::stable_iterator si) {
596 if (EHPersonality::get(*this).usesFuncletPads())
597 return getFuncletEHDispatchBlock(si);
599 // The dispatch block for the end of the scope chain is a block that
600 // just resumes unwinding.
601 if (si == EHStack.stable_end())
602 return getEHResumeBlock(true);
604 // Otherwise, we should look at the actual scope.
605 EHScope &scope = *EHStack.find(si);
607 llvm::BasicBlock *dispatchBlock = scope.getCachedEHDispatchBlock();
608 if (!dispatchBlock) {
609 switch (scope.getKind()) {
610 case EHScope::Catch: {
611 // Apply a special case to a single catch-all.
612 EHCatchScope &catchScope = cast<EHCatchScope>(scope);
613 if (catchScope.getNumHandlers() == 1 &&
614 catchScope.getHandler(0).isCatchAll()) {
615 dispatchBlock = catchScope.getHandler(0).Block;
617 // Otherwise, make a dispatch block.
619 dispatchBlock = createBasicBlock("catch.dispatch");
624 case EHScope::Cleanup:
625 dispatchBlock = createBasicBlock("ehcleanup");
628 case EHScope::Filter:
629 dispatchBlock = createBasicBlock("filter.dispatch");
632 case EHScope::Terminate:
633 dispatchBlock = getTerminateHandler();
636 case EHScope::PadEnd:
637 llvm_unreachable("PadEnd unnecessary for Itanium!");
639 scope.setCachedEHDispatchBlock(dispatchBlock);
641 return dispatchBlock;
645 CodeGenFunction::getFuncletEHDispatchBlock(EHScopeStack::stable_iterator SI) {
646 // Returning nullptr indicates that the previous dispatch block should unwind
648 if (SI == EHStack.stable_end())
651 // Otherwise, we should look at the actual scope.
652 EHScope &EHS = *EHStack.find(SI);
654 llvm::BasicBlock *DispatchBlock = EHS.getCachedEHDispatchBlock();
656 return DispatchBlock;
658 if (EHS.getKind() == EHScope::Terminate)
659 DispatchBlock = getTerminateFunclet();
661 DispatchBlock = createBasicBlock();
662 CGBuilderTy Builder(*this, DispatchBlock);
664 switch (EHS.getKind()) {
666 DispatchBlock->setName("catch.dispatch");
669 case EHScope::Cleanup:
670 DispatchBlock->setName("ehcleanup");
673 case EHScope::Filter:
674 llvm_unreachable("exception specifications not handled yet!");
676 case EHScope::Terminate:
677 DispatchBlock->setName("terminate");
680 case EHScope::PadEnd:
681 llvm_unreachable("PadEnd dispatch block missing!");
683 EHS.setCachedEHDispatchBlock(DispatchBlock);
684 return DispatchBlock;
687 /// Check whether this is a non-EH scope, i.e. a scope which doesn't
688 /// affect exception handling. Currently, the only non-EH scopes are
689 /// normal-only cleanup scopes.
690 static bool isNonEHScope(const EHScope &S) {
691 switch (S.getKind()) {
692 case EHScope::Cleanup:
693 return !cast<EHCleanupScope>(S).isEHCleanup();
694 case EHScope::Filter:
696 case EHScope::Terminate:
697 case EHScope::PadEnd:
701 llvm_unreachable("Invalid EHScope Kind!");
704 llvm::BasicBlock *CodeGenFunction::getInvokeDestImpl() {
705 assert(EHStack.requiresLandingPad());
706 assert(!EHStack.empty());
708 // If exceptions are disabled and SEH is not in use, then there is no invoke
709 // destination. SEH "works" even if exceptions are off. In practice, this
710 // means that C++ destructors and other EH cleanups don't run, which is
711 // consistent with MSVC's behavior.
712 const LangOptions &LO = CGM.getLangOpts();
713 if (!LO.Exceptions) {
714 if (!LO.Borland && !LO.MicrosoftExt)
716 if (!currentFunctionUsesSEHTry())
720 // CUDA device code doesn't have exceptions.
721 if (LO.CUDA && LO.CUDAIsDevice)
724 // Check the innermost scope for a cached landing pad. If this is
725 // a non-EH cleanup, we'll check enclosing scopes in EmitLandingPad.
726 llvm::BasicBlock *LP = EHStack.begin()->getCachedLandingPad();
729 const EHPersonality &Personality = EHPersonality::get(*this);
731 if (!CurFn->hasPersonalityFn())
732 CurFn->setPersonalityFn(getOpaquePersonalityFn(CGM, Personality));
734 if (Personality.usesFuncletPads()) {
735 // We don't need separate landing pads in the funclet model.
736 LP = getEHDispatchBlock(EHStack.getInnermostEHScope());
738 // Build the landing pad for this scope.
739 LP = EmitLandingPad();
744 // Cache the landing pad on the innermost scope. If this is a
745 // non-EH scope, cache the landing pad on the enclosing scope, too.
746 for (EHScopeStack::iterator ir = EHStack.begin(); true; ++ir) {
747 ir->setCachedLandingPad(LP);
748 if (!isNonEHScope(*ir)) break;
754 llvm::BasicBlock *CodeGenFunction::EmitLandingPad() {
755 assert(EHStack.requiresLandingPad());
757 EHScope &innermostEHScope = *EHStack.find(EHStack.getInnermostEHScope());
758 switch (innermostEHScope.getKind()) {
759 case EHScope::Terminate:
760 return getTerminateLandingPad();
762 case EHScope::PadEnd:
763 llvm_unreachable("PadEnd unnecessary for Itanium!");
766 case EHScope::Cleanup:
767 case EHScope::Filter:
768 if (llvm::BasicBlock *lpad = innermostEHScope.getCachedLandingPad())
772 // Save the current IR generation state.
773 CGBuilderTy::InsertPoint savedIP = Builder.saveAndClearIP();
774 auto DL = ApplyDebugLocation::CreateDefaultArtificial(*this, CurEHLocation);
776 // Create and configure the landing pad.
777 llvm::BasicBlock *lpad = createBasicBlock("lpad");
780 llvm::LandingPadInst *LPadInst =
781 Builder.CreateLandingPad(llvm::StructType::get(Int8PtrTy, Int32Ty), 0);
783 llvm::Value *LPadExn = Builder.CreateExtractValue(LPadInst, 0);
784 Builder.CreateStore(LPadExn, getExceptionSlot());
785 llvm::Value *LPadSel = Builder.CreateExtractValue(LPadInst, 1);
786 Builder.CreateStore(LPadSel, getEHSelectorSlot());
788 // Save the exception pointer. It's safe to use a single exception
789 // pointer per function because EH cleanups can never have nested
791 // Build the landingpad instruction.
793 // Accumulate all the handlers in scope.
794 bool hasCatchAll = false;
795 bool hasCleanup = false;
796 bool hasFilter = false;
797 SmallVector<llvm::Value*, 4> filterTypes;
798 llvm::SmallPtrSet<llvm::Value*, 4> catchTypes;
799 for (EHScopeStack::iterator I = EHStack.begin(), E = EHStack.end(); I != E;
802 switch (I->getKind()) {
803 case EHScope::Cleanup:
804 // If we have a cleanup, remember that.
805 hasCleanup = (hasCleanup || cast<EHCleanupScope>(*I).isEHCleanup());
808 case EHScope::Filter: {
809 assert(I.next() == EHStack.end() && "EH filter is not end of EH stack");
810 assert(!hasCatchAll && "EH filter reached after catch-all");
812 // Filter scopes get added to the landingpad in weird ways.
813 EHFilterScope &filter = cast<EHFilterScope>(*I);
816 // Add all the filter values.
817 for (unsigned i = 0, e = filter.getNumFilters(); i != e; ++i)
818 filterTypes.push_back(filter.getFilter(i));
822 case EHScope::Terminate:
823 // Terminate scopes are basically catch-alls.
824 assert(!hasCatchAll);
831 case EHScope::PadEnd:
832 llvm_unreachable("PadEnd unnecessary for Itanium!");
835 EHCatchScope &catchScope = cast<EHCatchScope>(*I);
836 for (unsigned hi = 0, he = catchScope.getNumHandlers(); hi != he; ++hi) {
837 EHCatchScope::Handler handler = catchScope.getHandler(hi);
838 assert(handler.Type.Flags == 0 &&
839 "landingpads do not support catch handler flags");
841 // If this is a catch-all, register that and abort.
842 if (!handler.Type.RTTI) {
843 assert(!hasCatchAll);
848 // Check whether we already have a handler for this type.
849 if (catchTypes.insert(handler.Type.RTTI).second)
850 // If not, add it directly to the landingpad.
851 LPadInst->addClause(handler.Type.RTTI);
856 // If we have a catch-all, add null to the landingpad.
857 assert(!(hasCatchAll && hasFilter));
859 LPadInst->addClause(getCatchAllValue(*this));
861 // If we have an EH filter, we need to add those handlers in the
862 // right place in the landingpad, which is to say, at the end.
863 } else if (hasFilter) {
864 // Create a filter expression: a constant array indicating which filter
865 // types there are. The personality routine only lands here if the filter
867 SmallVector<llvm::Constant*, 8> Filters;
868 llvm::ArrayType *AType =
869 llvm::ArrayType::get(!filterTypes.empty() ?
870 filterTypes[0]->getType() : Int8PtrTy,
873 for (unsigned i = 0, e = filterTypes.size(); i != e; ++i)
874 Filters.push_back(cast<llvm::Constant>(filterTypes[i]));
875 llvm::Constant *FilterArray = llvm::ConstantArray::get(AType, Filters);
876 LPadInst->addClause(FilterArray);
878 // Also check whether we need a cleanup.
880 LPadInst->setCleanup(true);
882 // Otherwise, signal that we at least have cleanups.
883 } else if (hasCleanup) {
884 LPadInst->setCleanup(true);
887 assert((LPadInst->getNumClauses() > 0 || LPadInst->isCleanup()) &&
888 "landingpad instruction has no clauses!");
890 // Tell the backend how to generate the landing pad.
891 Builder.CreateBr(getEHDispatchBlock(EHStack.getInnermostEHScope()));
893 // Restore the old IR generation state.
894 Builder.restoreIP(savedIP);
899 static void emitCatchPadBlock(CodeGenFunction &CGF, EHCatchScope &CatchScope) {
900 llvm::BasicBlock *DispatchBlock = CatchScope.getCachedEHDispatchBlock();
901 assert(DispatchBlock);
903 CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveIP();
904 CGF.EmitBlockAfterUses(DispatchBlock);
906 llvm::Value *ParentPad = CGF.CurrentFuncletPad;
908 ParentPad = llvm::ConstantTokenNone::get(CGF.getLLVMContext());
909 llvm::BasicBlock *UnwindBB =
910 CGF.getEHDispatchBlock(CatchScope.getEnclosingEHScope());
912 unsigned NumHandlers = CatchScope.getNumHandlers();
913 llvm::CatchSwitchInst *CatchSwitch =
914 CGF.Builder.CreateCatchSwitch(ParentPad, UnwindBB, NumHandlers);
916 // Test against each of the exception types we claim to catch.
917 for (unsigned I = 0; I < NumHandlers; ++I) {
918 const EHCatchScope::Handler &Handler = CatchScope.getHandler(I);
920 CatchTypeInfo TypeInfo = Handler.Type;
922 TypeInfo.RTTI = llvm::Constant::getNullValue(CGF.VoidPtrTy);
924 CGF.Builder.SetInsertPoint(Handler.Block);
926 if (EHPersonality::get(CGF).isMSVCXXPersonality()) {
927 CGF.Builder.CreateCatchPad(
928 CatchSwitch, {TypeInfo.RTTI, CGF.Builder.getInt32(TypeInfo.Flags),
929 llvm::Constant::getNullValue(CGF.VoidPtrTy)});
931 CGF.Builder.CreateCatchPad(CatchSwitch, {TypeInfo.RTTI});
934 CatchSwitch->addHandler(Handler.Block);
936 CGF.Builder.restoreIP(SavedIP);
939 // Wasm uses Windows-style EH instructions, but it merges all catch clauses into
940 // one big catchpad, within which we use Itanium's landingpad-style selector
941 // comparison instructions.
942 static void emitWasmCatchPadBlock(CodeGenFunction &CGF,
943 EHCatchScope &CatchScope) {
944 llvm::BasicBlock *DispatchBlock = CatchScope.getCachedEHDispatchBlock();
945 assert(DispatchBlock);
947 CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveIP();
948 CGF.EmitBlockAfterUses(DispatchBlock);
950 llvm::Value *ParentPad = CGF.CurrentFuncletPad;
952 ParentPad = llvm::ConstantTokenNone::get(CGF.getLLVMContext());
953 llvm::BasicBlock *UnwindBB =
954 CGF.getEHDispatchBlock(CatchScope.getEnclosingEHScope());
956 unsigned NumHandlers = CatchScope.getNumHandlers();
957 llvm::CatchSwitchInst *CatchSwitch =
958 CGF.Builder.CreateCatchSwitch(ParentPad, UnwindBB, NumHandlers);
960 // We don't use a landingpad instruction, so generate intrinsic calls to
961 // provide exception and selector values.
962 llvm::BasicBlock *WasmCatchStartBlock = CGF.createBasicBlock("catch.start");
963 CatchSwitch->addHandler(WasmCatchStartBlock);
964 CGF.EmitBlockAfterUses(WasmCatchStartBlock);
966 // Create a catchpad instruction.
967 SmallVector<llvm::Value *, 4> CatchTypes;
968 for (unsigned I = 0, E = NumHandlers; I < E; ++I) {
969 const EHCatchScope::Handler &Handler = CatchScope.getHandler(I);
970 CatchTypeInfo TypeInfo = Handler.Type;
972 TypeInfo.RTTI = llvm::Constant::getNullValue(CGF.VoidPtrTy);
973 CatchTypes.push_back(TypeInfo.RTTI);
975 auto *CPI = CGF.Builder.CreateCatchPad(CatchSwitch, CatchTypes);
977 // Create calls to wasm.get.exception and wasm.get.ehselector intrinsics.
978 // Before they are lowered appropriately later, they provide values for the
979 // exception and selector.
980 llvm::Function *GetExnFn =
981 CGF.CGM.getIntrinsic(llvm::Intrinsic::wasm_get_exception);
982 llvm::Function *GetSelectorFn =
983 CGF.CGM.getIntrinsic(llvm::Intrinsic::wasm_get_ehselector);
984 llvm::CallInst *Exn = CGF.Builder.CreateCall(GetExnFn, CPI);
985 CGF.Builder.CreateStore(Exn, CGF.getExceptionSlot());
986 llvm::CallInst *Selector = CGF.Builder.CreateCall(GetSelectorFn, CPI);
988 llvm::Function *TypeIDFn = CGF.CGM.getIntrinsic(llvm::Intrinsic::eh_typeid_for);
990 // If there's only a single catch-all, branch directly to its handler.
991 if (CatchScope.getNumHandlers() == 1 &&
992 CatchScope.getHandler(0).isCatchAll()) {
993 CGF.Builder.CreateBr(CatchScope.getHandler(0).Block);
994 CGF.Builder.restoreIP(SavedIP);
998 // Test against each of the exception types we claim to catch.
999 for (unsigned I = 0, E = NumHandlers;; ++I) {
1000 assert(I < E && "ran off end of handlers!");
1001 const EHCatchScope::Handler &Handler = CatchScope.getHandler(I);
1002 CatchTypeInfo TypeInfo = Handler.Type;
1004 TypeInfo.RTTI = llvm::Constant::getNullValue(CGF.VoidPtrTy);
1006 // Figure out the next block.
1007 llvm::BasicBlock *NextBlock;
1009 bool EmitNextBlock = false, NextIsEnd = false;
1011 // If this is the last handler, we're at the end, and the next block is a
1012 // block that contains a call to the rethrow function, so we can unwind to
1013 // the enclosing EH scope. The call itself will be generated later.
1015 NextBlock = CGF.createBasicBlock("rethrow");
1016 EmitNextBlock = true;
1019 // If the next handler is a catch-all, we're at the end, and the
1020 // next block is that handler.
1021 } else if (CatchScope.getHandler(I + 1).isCatchAll()) {
1022 NextBlock = CatchScope.getHandler(I + 1).Block;
1025 // Otherwise, we're not at the end and we need a new block.
1027 NextBlock = CGF.createBasicBlock("catch.fallthrough");
1028 EmitNextBlock = true;
1031 // Figure out the catch type's index in the LSDA's type table.
1032 llvm::CallInst *TypeIndex = CGF.Builder.CreateCall(TypeIDFn, TypeInfo.RTTI);
1033 TypeIndex->setDoesNotThrow();
1035 llvm::Value *MatchesTypeIndex =
1036 CGF.Builder.CreateICmpEQ(Selector, TypeIndex, "matches");
1037 CGF.Builder.CreateCondBr(MatchesTypeIndex, Handler.Block, NextBlock);
1040 CGF.EmitBlock(NextBlock);
1045 CGF.Builder.restoreIP(SavedIP);
1048 /// Emit the structure of the dispatch block for the given catch scope.
1049 /// It is an invariant that the dispatch block already exists.
1050 static void emitCatchDispatchBlock(CodeGenFunction &CGF,
1051 EHCatchScope &catchScope) {
1052 if (EHPersonality::get(CGF).isWasmPersonality())
1053 return emitWasmCatchPadBlock(CGF, catchScope);
1054 if (EHPersonality::get(CGF).usesFuncletPads())
1055 return emitCatchPadBlock(CGF, catchScope);
1057 llvm::BasicBlock *dispatchBlock = catchScope.getCachedEHDispatchBlock();
1058 assert(dispatchBlock);
1060 // If there's only a single catch-all, getEHDispatchBlock returned
1061 // that catch-all as the dispatch block.
1062 if (catchScope.getNumHandlers() == 1 &&
1063 catchScope.getHandler(0).isCatchAll()) {
1064 assert(dispatchBlock == catchScope.getHandler(0).Block);
1068 CGBuilderTy::InsertPoint savedIP = CGF.Builder.saveIP();
1069 CGF.EmitBlockAfterUses(dispatchBlock);
1071 // Select the right handler.
1072 llvm::Function *llvm_eh_typeid_for =
1073 CGF.CGM.getIntrinsic(llvm::Intrinsic::eh_typeid_for);
1075 // Load the selector value.
1076 llvm::Value *selector = CGF.getSelectorFromSlot();
1078 // Test against each of the exception types we claim to catch.
1079 for (unsigned i = 0, e = catchScope.getNumHandlers(); ; ++i) {
1080 assert(i < e && "ran off end of handlers!");
1081 const EHCatchScope::Handler &handler = catchScope.getHandler(i);
1083 llvm::Value *typeValue = handler.Type.RTTI;
1084 assert(handler.Type.Flags == 0 &&
1085 "landingpads do not support catch handler flags");
1086 assert(typeValue && "fell into catch-all case!");
1087 typeValue = CGF.Builder.CreateBitCast(typeValue, CGF.Int8PtrTy);
1089 // Figure out the next block.
1091 llvm::BasicBlock *nextBlock;
1093 // If this is the last handler, we're at the end, and the next
1094 // block is the block for the enclosing EH scope.
1096 nextBlock = CGF.getEHDispatchBlock(catchScope.getEnclosingEHScope());
1099 // If the next handler is a catch-all, we're at the end, and the
1100 // next block is that handler.
1101 } else if (catchScope.getHandler(i+1).isCatchAll()) {
1102 nextBlock = catchScope.getHandler(i+1).Block;
1105 // Otherwise, we're not at the end and we need a new block.
1107 nextBlock = CGF.createBasicBlock("catch.fallthrough");
1111 // Figure out the catch type's index in the LSDA's type table.
1112 llvm::CallInst *typeIndex =
1113 CGF.Builder.CreateCall(llvm_eh_typeid_for, typeValue);
1114 typeIndex->setDoesNotThrow();
1116 llvm::Value *matchesTypeIndex =
1117 CGF.Builder.CreateICmpEQ(selector, typeIndex, "matches");
1118 CGF.Builder.CreateCondBr(matchesTypeIndex, handler.Block, nextBlock);
1120 // If the next handler is a catch-all, we're completely done.
1122 CGF.Builder.restoreIP(savedIP);
1125 // Otherwise we need to emit and continue at that block.
1126 CGF.EmitBlock(nextBlock);
1130 void CodeGenFunction::popCatchScope() {
1131 EHCatchScope &catchScope = cast<EHCatchScope>(*EHStack.begin());
1132 if (catchScope.hasEHBranches())
1133 emitCatchDispatchBlock(*this, catchScope);
1137 void CodeGenFunction::ExitCXXTryStmt(const CXXTryStmt &S, bool IsFnTryBlock) {
1138 unsigned NumHandlers = S.getNumHandlers();
1139 EHCatchScope &CatchScope = cast<EHCatchScope>(*EHStack.begin());
1140 assert(CatchScope.getNumHandlers() == NumHandlers);
1141 llvm::BasicBlock *DispatchBlock = CatchScope.getCachedEHDispatchBlock();
1143 // If the catch was not required, bail out now.
1144 if (!CatchScope.hasEHBranches()) {
1145 CatchScope.clearHandlerBlocks();
1150 // Emit the structure of the EH dispatch for this catch.
1151 emitCatchDispatchBlock(*this, CatchScope);
1153 // Copy the handler blocks off before we pop the EH stack. Emitting
1154 // the handlers might scribble on this memory.
1155 SmallVector<EHCatchScope::Handler, 8> Handlers(
1156 CatchScope.begin(), CatchScope.begin() + NumHandlers);
1160 // The fall-through block.
1161 llvm::BasicBlock *ContBB = createBasicBlock("try.cont");
1163 // We just emitted the body of the try; jump to the continue block.
1164 if (HaveInsertPoint())
1165 Builder.CreateBr(ContBB);
1167 // Determine if we need an implicit rethrow for all these catch handlers;
1168 // see the comment below.
1169 bool doImplicitRethrow = false;
1171 doImplicitRethrow = isa<CXXDestructorDecl>(CurCodeDecl) ||
1172 isa<CXXConstructorDecl>(CurCodeDecl);
1174 // Wasm uses Windows-style EH instructions, but merges all catch clauses into
1175 // one big catchpad. So we save the old funclet pad here before we traverse
1176 // each catch handler.
1177 SaveAndRestore<llvm::Instruction *> RestoreCurrentFuncletPad(
1179 llvm::BasicBlock *WasmCatchStartBlock = nullptr;
1180 if (EHPersonality::get(*this).isWasmPersonality()) {
1182 cast<llvm::CatchSwitchInst>(DispatchBlock->getFirstNonPHI());
1183 WasmCatchStartBlock = CatchSwitch->hasUnwindDest()
1184 ? CatchSwitch->getSuccessor(1)
1185 : CatchSwitch->getSuccessor(0);
1186 auto *CPI = cast<llvm::CatchPadInst>(WasmCatchStartBlock->getFirstNonPHI());
1187 CurrentFuncletPad = CPI;
1190 // Perversely, we emit the handlers backwards precisely because we
1191 // want them to appear in source order. In all of these cases, the
1192 // catch block will have exactly one predecessor, which will be a
1193 // particular block in the catch dispatch. However, in the case of
1194 // a catch-all, one of the dispatch blocks will branch to two
1195 // different handlers, and EmitBlockAfterUses will cause the second
1196 // handler to be moved before the first.
1197 bool HasCatchAll = false;
1198 for (unsigned I = NumHandlers; I != 0; --I) {
1199 HasCatchAll |= Handlers[I - 1].isCatchAll();
1200 llvm::BasicBlock *CatchBlock = Handlers[I-1].Block;
1201 EmitBlockAfterUses(CatchBlock);
1203 // Catch the exception if this isn't a catch-all.
1204 const CXXCatchStmt *C = S.getHandler(I-1);
1206 // Enter a cleanup scope, including the catch variable and the
1208 RunCleanupsScope CatchScope(*this);
1210 // Initialize the catch variable and set up the cleanups.
1211 SaveAndRestore<llvm::Instruction *> RestoreCurrentFuncletPad(
1213 CGM.getCXXABI().emitBeginCatch(*this, C);
1215 // Emit the PGO counter increment.
1216 incrementProfileCounter(C);
1218 // Perform the body of the catch.
1219 EmitStmt(C->getHandlerBlock());
1221 // [except.handle]p11:
1222 // The currently handled exception is rethrown if control
1223 // reaches the end of a handler of the function-try-block of a
1224 // constructor or destructor.
1226 // It is important that we only do this on fallthrough and not on
1227 // return. Note that it's illegal to put a return in a
1228 // constructor function-try-block's catch handler (p14), so this
1229 // really only applies to destructors.
1230 if (doImplicitRethrow && HaveInsertPoint()) {
1231 CGM.getCXXABI().emitRethrow(*this, /*isNoReturn*/false);
1232 Builder.CreateUnreachable();
1233 Builder.ClearInsertionPoint();
1236 // Fall out through the catch cleanups.
1237 CatchScope.ForceCleanup();
1239 // Branch out of the try.
1240 if (HaveInsertPoint())
1241 Builder.CreateBr(ContBB);
1244 // Because in wasm we merge all catch clauses into one big catchpad, in case
1245 // none of the types in catch handlers matches after we test against each of
1246 // them, we should unwind to the next EH enclosing scope. We generate a call
1247 // to rethrow function here to do that.
1248 if (EHPersonality::get(*this).isWasmPersonality() && !HasCatchAll) {
1249 assert(WasmCatchStartBlock);
1250 // Navigate for the "rethrow" block we created in emitWasmCatchPadBlock().
1251 // Wasm uses landingpad-style conditional branches to compare selectors, so
1252 // we follow the false destination for each of the cond branches to reach
1253 // the rethrow block.
1254 llvm::BasicBlock *RethrowBlock = WasmCatchStartBlock;
1255 while (llvm::Instruction *TI = RethrowBlock->getTerminator()) {
1256 auto *BI = cast<llvm::BranchInst>(TI);
1257 assert(BI->isConditional());
1258 RethrowBlock = BI->getSuccessor(1);
1260 assert(RethrowBlock != WasmCatchStartBlock && RethrowBlock->empty());
1261 Builder.SetInsertPoint(RethrowBlock);
1262 llvm::Function *RethrowInCatchFn =
1263 CGM.getIntrinsic(llvm::Intrinsic::wasm_rethrow_in_catch);
1264 EmitNoreturnRuntimeCallOrInvoke(RethrowInCatchFn, {});
1268 incrementProfileCounter(&S);
1272 struct CallEndCatchForFinally final : EHScopeStack::Cleanup {
1273 llvm::Value *ForEHVar;
1274 llvm::FunctionCallee EndCatchFn;
1275 CallEndCatchForFinally(llvm::Value *ForEHVar,
1276 llvm::FunctionCallee EndCatchFn)
1277 : ForEHVar(ForEHVar), EndCatchFn(EndCatchFn) {}
1279 void Emit(CodeGenFunction &CGF, Flags flags) override {
1280 llvm::BasicBlock *EndCatchBB = CGF.createBasicBlock("finally.endcatch");
1281 llvm::BasicBlock *CleanupContBB =
1282 CGF.createBasicBlock("finally.cleanup.cont");
1284 llvm::Value *ShouldEndCatch =
1285 CGF.Builder.CreateFlagLoad(ForEHVar, "finally.endcatch");
1286 CGF.Builder.CreateCondBr(ShouldEndCatch, EndCatchBB, CleanupContBB);
1287 CGF.EmitBlock(EndCatchBB);
1288 CGF.EmitRuntimeCallOrInvoke(EndCatchFn); // catch-all, so might throw
1289 CGF.EmitBlock(CleanupContBB);
1293 struct PerformFinally final : EHScopeStack::Cleanup {
1295 llvm::Value *ForEHVar;
1296 llvm::FunctionCallee EndCatchFn;
1297 llvm::FunctionCallee RethrowFn;
1298 llvm::Value *SavedExnVar;
1300 PerformFinally(const Stmt *Body, llvm::Value *ForEHVar,
1301 llvm::FunctionCallee EndCatchFn,
1302 llvm::FunctionCallee RethrowFn, llvm::Value *SavedExnVar)
1303 : Body(Body), ForEHVar(ForEHVar), EndCatchFn(EndCatchFn),
1304 RethrowFn(RethrowFn), SavedExnVar(SavedExnVar) {}
1306 void Emit(CodeGenFunction &CGF, Flags flags) override {
1307 // Enter a cleanup to call the end-catch function if one was provided.
1309 CGF.EHStack.pushCleanup<CallEndCatchForFinally>(NormalAndEHCleanup,
1310 ForEHVar, EndCatchFn);
1312 // Save the current cleanup destination in case there are
1313 // cleanups in the finally block.
1314 llvm::Value *SavedCleanupDest =
1315 CGF.Builder.CreateLoad(CGF.getNormalCleanupDestSlot(),
1316 "cleanup.dest.saved");
1318 // Emit the finally block.
1321 // If the end of the finally is reachable, check whether this was
1322 // for EH. If so, rethrow.
1323 if (CGF.HaveInsertPoint()) {
1324 llvm::BasicBlock *RethrowBB = CGF.createBasicBlock("finally.rethrow");
1325 llvm::BasicBlock *ContBB = CGF.createBasicBlock("finally.cont");
1327 llvm::Value *ShouldRethrow =
1328 CGF.Builder.CreateFlagLoad(ForEHVar, "finally.shouldthrow");
1329 CGF.Builder.CreateCondBr(ShouldRethrow, RethrowBB, ContBB);
1331 CGF.EmitBlock(RethrowBB);
1333 CGF.EmitRuntimeCallOrInvoke(RethrowFn,
1334 CGF.Builder.CreateAlignedLoad(SavedExnVar, CGF.getPointerAlign()));
1336 CGF.EmitRuntimeCallOrInvoke(RethrowFn);
1338 CGF.Builder.CreateUnreachable();
1340 CGF.EmitBlock(ContBB);
1342 // Restore the cleanup destination.
1343 CGF.Builder.CreateStore(SavedCleanupDest,
1344 CGF.getNormalCleanupDestSlot());
1347 // Leave the end-catch cleanup. As an optimization, pretend that
1348 // the fallthrough path was inaccessible; we've dynamically proven
1349 // that we're not in the EH case along that path.
1351 CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveAndClearIP();
1352 CGF.PopCleanupBlock();
1353 CGF.Builder.restoreIP(SavedIP);
1356 // Now make sure we actually have an insertion point or the
1357 // cleanup gods will hate us.
1358 CGF.EnsureInsertPoint();
1361 } // end anonymous namespace
1363 /// Enters a finally block for an implementation using zero-cost
1364 /// exceptions. This is mostly general, but hard-codes some
1365 /// language/ABI-specific behavior in the catch-all sections.
1366 void CodeGenFunction::FinallyInfo::enter(CodeGenFunction &CGF, const Stmt *body,
1367 llvm::FunctionCallee beginCatchFn,
1368 llvm::FunctionCallee endCatchFn,
1369 llvm::FunctionCallee rethrowFn) {
1370 assert((!!beginCatchFn) == (!!endCatchFn) &&
1371 "begin/end catch functions not paired");
1372 assert(rethrowFn && "rethrow function is required");
1374 BeginCatchFn = beginCatchFn;
1376 // The rethrow function has one of the following two types:
1379 // In the latter case we need to pass it the exception object.
1380 // But we can't use the exception slot because the @finally might
1381 // have a landing pad (which would overwrite the exception slot).
1382 llvm::FunctionType *rethrowFnTy = rethrowFn.getFunctionType();
1383 SavedExnVar = nullptr;
1384 if (rethrowFnTy->getNumParams())
1385 SavedExnVar = CGF.CreateTempAlloca(CGF.Int8PtrTy, "finally.exn");
1387 // A finally block is a statement which must be executed on any edge
1388 // out of a given scope. Unlike a cleanup, the finally block may
1389 // contain arbitrary control flow leading out of itself. In
1390 // addition, finally blocks should always be executed, even if there
1391 // are no catch handlers higher on the stack. Therefore, we
1392 // surround the protected scope with a combination of a normal
1393 // cleanup (to catch attempts to break out of the block via normal
1394 // control flow) and an EH catch-all (semantically "outside" any try
1395 // statement to which the finally block might have been attached).
1396 // The finally block itself is generated in the context of a cleanup
1397 // which conditionally leaves the catch-all.
1399 // Jump destination for performing the finally block on an exception
1400 // edge. We'll never actually reach this block, so unreachable is
1402 RethrowDest = CGF.getJumpDestInCurrentScope(CGF.getUnreachableBlock());
1404 // Whether the finally block is being executed for EH purposes.
1405 ForEHVar = CGF.CreateTempAlloca(CGF.Builder.getInt1Ty(), "finally.for-eh");
1406 CGF.Builder.CreateFlagStore(false, ForEHVar);
1408 // Enter a normal cleanup which will perform the @finally block.
1409 CGF.EHStack.pushCleanup<PerformFinally>(NormalCleanup, body,
1410 ForEHVar, endCatchFn,
1411 rethrowFn, SavedExnVar);
1413 // Enter a catch-all scope.
1414 llvm::BasicBlock *catchBB = CGF.createBasicBlock("finally.catchall");
1415 EHCatchScope *catchScope = CGF.EHStack.pushCatch(1);
1416 catchScope->setCatchAllHandler(0, catchBB);
1419 void CodeGenFunction::FinallyInfo::exit(CodeGenFunction &CGF) {
1420 // Leave the finally catch-all.
1421 EHCatchScope &catchScope = cast<EHCatchScope>(*CGF.EHStack.begin());
1422 llvm::BasicBlock *catchBB = catchScope.getHandler(0).Block;
1424 CGF.popCatchScope();
1426 // If there are any references to the catch-all block, emit it.
1427 if (catchBB->use_empty()) {
1430 CGBuilderTy::InsertPoint savedIP = CGF.Builder.saveAndClearIP();
1431 CGF.EmitBlock(catchBB);
1433 llvm::Value *exn = nullptr;
1435 // If there's a begin-catch function, call it.
1437 exn = CGF.getExceptionFromSlot();
1438 CGF.EmitNounwindRuntimeCall(BeginCatchFn, exn);
1441 // If we need to remember the exception pointer to rethrow later, do so.
1443 if (!exn) exn = CGF.getExceptionFromSlot();
1444 CGF.Builder.CreateAlignedStore(exn, SavedExnVar, CGF.getPointerAlign());
1447 // Tell the cleanups in the finally block that we're do this for EH.
1448 CGF.Builder.CreateFlagStore(true, ForEHVar);
1450 // Thread a jump through the finally cleanup.
1451 CGF.EmitBranchThroughCleanup(RethrowDest);
1453 CGF.Builder.restoreIP(savedIP);
1456 // Finally, leave the @finally cleanup.
1457 CGF.PopCleanupBlock();
1460 llvm::BasicBlock *CodeGenFunction::getTerminateLandingPad() {
1461 if (TerminateLandingPad)
1462 return TerminateLandingPad;
1464 CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
1466 // This will get inserted at the end of the function.
1467 TerminateLandingPad = createBasicBlock("terminate.lpad");
1468 Builder.SetInsertPoint(TerminateLandingPad);
1470 // Tell the backend that this is a landing pad.
1471 const EHPersonality &Personality = EHPersonality::get(*this);
1473 if (!CurFn->hasPersonalityFn())
1474 CurFn->setPersonalityFn(getOpaquePersonalityFn(CGM, Personality));
1476 llvm::LandingPadInst *LPadInst =
1477 Builder.CreateLandingPad(llvm::StructType::get(Int8PtrTy, Int32Ty), 0);
1478 LPadInst->addClause(getCatchAllValue(*this));
1480 llvm::Value *Exn = nullptr;
1481 if (getLangOpts().CPlusPlus)
1482 Exn = Builder.CreateExtractValue(LPadInst, 0);
1483 llvm::CallInst *terminateCall =
1484 CGM.getCXXABI().emitTerminateForUnexpectedException(*this, Exn);
1485 terminateCall->setDoesNotReturn();
1486 Builder.CreateUnreachable();
1488 // Restore the saved insertion state.
1489 Builder.restoreIP(SavedIP);
1491 return TerminateLandingPad;
1494 llvm::BasicBlock *CodeGenFunction::getTerminateHandler() {
1495 if (TerminateHandler)
1496 return TerminateHandler;
1498 // Set up the terminate handler. This block is inserted at the very
1499 // end of the function by FinishFunction.
1500 TerminateHandler = createBasicBlock("terminate.handler");
1501 CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
1502 Builder.SetInsertPoint(TerminateHandler);
1504 llvm::Value *Exn = nullptr;
1505 if (getLangOpts().CPlusPlus)
1506 Exn = getExceptionFromSlot();
1507 llvm::CallInst *terminateCall =
1508 CGM.getCXXABI().emitTerminateForUnexpectedException(*this, Exn);
1509 terminateCall->setDoesNotReturn();
1510 Builder.CreateUnreachable();
1512 // Restore the saved insertion state.
1513 Builder.restoreIP(SavedIP);
1515 return TerminateHandler;
1518 llvm::BasicBlock *CodeGenFunction::getTerminateFunclet() {
1519 assert(EHPersonality::get(*this).usesFuncletPads() &&
1520 "use getTerminateLandingPad for non-funclet EH");
1522 llvm::BasicBlock *&TerminateFunclet = TerminateFunclets[CurrentFuncletPad];
1523 if (TerminateFunclet)
1524 return TerminateFunclet;
1526 CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
1528 // Set up the terminate handler. This block is inserted at the very
1529 // end of the function by FinishFunction.
1530 TerminateFunclet = createBasicBlock("terminate.handler");
1531 Builder.SetInsertPoint(TerminateFunclet);
1533 // Create the cleanuppad using the current parent pad as its token. Use 'none'
1534 // if this is a top-level terminate scope, which is the common case.
1535 SaveAndRestore<llvm::Instruction *> RestoreCurrentFuncletPad(
1537 llvm::Value *ParentPad = CurrentFuncletPad;
1539 ParentPad = llvm::ConstantTokenNone::get(CGM.getLLVMContext());
1540 CurrentFuncletPad = Builder.CreateCleanupPad(ParentPad);
1542 // Emit the __std_terminate call.
1543 llvm::Value *Exn = nullptr;
1544 // In case of wasm personality, we need to pass the exception value to
1545 // __clang_call_terminate function.
1546 if (getLangOpts().CPlusPlus &&
1547 EHPersonality::get(*this).isWasmPersonality()) {
1548 llvm::Function *GetExnFn =
1549 CGM.getIntrinsic(llvm::Intrinsic::wasm_get_exception);
1550 Exn = Builder.CreateCall(GetExnFn, CurrentFuncletPad);
1552 llvm::CallInst *terminateCall =
1553 CGM.getCXXABI().emitTerminateForUnexpectedException(*this, Exn);
1554 terminateCall->setDoesNotReturn();
1555 Builder.CreateUnreachable();
1557 // Restore the saved insertion state.
1558 Builder.restoreIP(SavedIP);
1560 return TerminateFunclet;
1563 llvm::BasicBlock *CodeGenFunction::getEHResumeBlock(bool isCleanup) {
1564 if (EHResumeBlock) return EHResumeBlock;
1566 CGBuilderTy::InsertPoint SavedIP = Builder.saveIP();
1568 // We emit a jump to a notional label at the outermost unwind state.
1569 EHResumeBlock = createBasicBlock("eh.resume");
1570 Builder.SetInsertPoint(EHResumeBlock);
1572 const EHPersonality &Personality = EHPersonality::get(*this);
1574 // This can always be a call because we necessarily didn't find
1575 // anything on the EH stack which needs our help.
1576 const char *RethrowName = Personality.CatchallRethrowFn;
1577 if (RethrowName != nullptr && !isCleanup) {
1578 EmitRuntimeCall(getCatchallRethrowFn(CGM, RethrowName),
1579 getExceptionFromSlot())->setDoesNotReturn();
1580 Builder.CreateUnreachable();
1581 Builder.restoreIP(SavedIP);
1582 return EHResumeBlock;
1585 // Recreate the landingpad's return value for the 'resume' instruction.
1586 llvm::Value *Exn = getExceptionFromSlot();
1587 llvm::Value *Sel = getSelectorFromSlot();
1589 llvm::Type *LPadType = llvm::StructType::get(Exn->getType(), Sel->getType());
1590 llvm::Value *LPadVal = llvm::UndefValue::get(LPadType);
1591 LPadVal = Builder.CreateInsertValue(LPadVal, Exn, 0, "lpad.val");
1592 LPadVal = Builder.CreateInsertValue(LPadVal, Sel, 1, "lpad.val");
1594 Builder.CreateResume(LPadVal);
1595 Builder.restoreIP(SavedIP);
1596 return EHResumeBlock;
1599 void CodeGenFunction::EmitSEHTryStmt(const SEHTryStmt &S) {
1602 JumpDest TryExit = getJumpDestInCurrentScope("__try.__leave");
1604 SEHTryEpilogueStack.push_back(&TryExit);
1605 EmitStmt(S.getTryBlock());
1606 SEHTryEpilogueStack.pop_back();
1608 if (!TryExit.getBlock()->use_empty())
1609 EmitBlock(TryExit.getBlock(), /*IsFinished=*/true);
1611 delete TryExit.getBlock();
1617 struct PerformSEHFinally final : EHScopeStack::Cleanup {
1618 llvm::Function *OutlinedFinally;
1619 PerformSEHFinally(llvm::Function *OutlinedFinally)
1620 : OutlinedFinally(OutlinedFinally) {}
1622 void Emit(CodeGenFunction &CGF, Flags F) override {
1623 ASTContext &Context = CGF.getContext();
1624 CodeGenModule &CGM = CGF.CGM;
1628 // Compute the two argument values.
1629 QualType ArgTys[2] = {Context.UnsignedCharTy, Context.VoidPtrTy};
1630 llvm::Value *FP = nullptr;
1631 // If CFG.IsOutlinedSEHHelper is true, then we are within a finally block.
1632 if (CGF.IsOutlinedSEHHelper) {
1633 FP = &CGF.CurFn->arg_begin()[1];
1635 llvm::Function *LocalAddrFn =
1636 CGM.getIntrinsic(llvm::Intrinsic::localaddress);
1637 FP = CGF.Builder.CreateCall(LocalAddrFn);
1640 llvm::Value *IsForEH =
1641 llvm::ConstantInt::get(CGF.ConvertType(ArgTys[0]), F.isForEHCleanup());
1642 Args.add(RValue::get(IsForEH), ArgTys[0]);
1643 Args.add(RValue::get(FP), ArgTys[1]);
1645 // Arrange a two-arg function info and type.
1646 const CGFunctionInfo &FnInfo =
1647 CGM.getTypes().arrangeBuiltinFunctionCall(Context.VoidTy, Args);
1649 auto Callee = CGCallee::forDirect(OutlinedFinally);
1650 CGF.EmitCall(FnInfo, Callee, ReturnValueSlot(), Args);
1653 } // end anonymous namespace
1656 /// Find all local variable captures in the statement.
1657 struct CaptureFinder : ConstStmtVisitor<CaptureFinder> {
1658 CodeGenFunction &ParentCGF;
1659 const VarDecl *ParentThis;
1660 llvm::SmallSetVector<const VarDecl *, 4> Captures;
1661 Address SEHCodeSlot = Address::invalid();
1662 CaptureFinder(CodeGenFunction &ParentCGF, const VarDecl *ParentThis)
1663 : ParentCGF(ParentCGF), ParentThis(ParentThis) {}
1665 // Return true if we need to do any capturing work.
1666 bool foundCaptures() {
1667 return !Captures.empty() || SEHCodeSlot.isValid();
1670 void Visit(const Stmt *S) {
1671 // See if this is a capture, then recurse.
1672 ConstStmtVisitor<CaptureFinder>::Visit(S);
1673 for (const Stmt *Child : S->children())
1678 void VisitDeclRefExpr(const DeclRefExpr *E) {
1679 // If this is already a capture, just make sure we capture 'this'.
1680 if (E->refersToEnclosingVariableOrCapture()) {
1681 Captures.insert(ParentThis);
1685 const auto *D = dyn_cast<VarDecl>(E->getDecl());
1686 if (D && D->isLocalVarDeclOrParm() && D->hasLocalStorage())
1690 void VisitCXXThisExpr(const CXXThisExpr *E) {
1691 Captures.insert(ParentThis);
1694 void VisitCallExpr(const CallExpr *E) {
1695 // We only need to add parent frame allocations for these builtins in x86.
1696 if (ParentCGF.getTarget().getTriple().getArch() != llvm::Triple::x86)
1699 unsigned ID = E->getBuiltinCallee();
1701 case Builtin::BI__exception_code:
1702 case Builtin::BI_exception_code:
1703 // This is the simple case where we are the outermost finally. All we
1704 // have to do here is make sure we escape this and recover it in the
1705 // outlined handler.
1706 if (!SEHCodeSlot.isValid())
1707 SEHCodeSlot = ParentCGF.SEHCodeSlotStack.back();
1712 } // end anonymous namespace
1714 Address CodeGenFunction::recoverAddrOfEscapedLocal(CodeGenFunction &ParentCGF,
1716 llvm::Value *ParentFP) {
1717 llvm::CallInst *RecoverCall = nullptr;
1718 CGBuilderTy Builder(*this, AllocaInsertPt);
1719 if (auto *ParentAlloca = dyn_cast<llvm::AllocaInst>(ParentVar.getPointer())) {
1720 // Mark the variable escaped if nobody else referenced it and compute the
1721 // localescape index.
1722 auto InsertPair = ParentCGF.EscapedLocals.insert(
1723 std::make_pair(ParentAlloca, ParentCGF.EscapedLocals.size()));
1724 int FrameEscapeIdx = InsertPair.first->second;
1725 // call i8* @llvm.localrecover(i8* bitcast(@parentFn), i8* %fp, i32 N)
1726 llvm::Function *FrameRecoverFn = llvm::Intrinsic::getDeclaration(
1727 &CGM.getModule(), llvm::Intrinsic::localrecover);
1728 llvm::Constant *ParentI8Fn =
1729 llvm::ConstantExpr::getBitCast(ParentCGF.CurFn, Int8PtrTy);
1730 RecoverCall = Builder.CreateCall(
1731 FrameRecoverFn, {ParentI8Fn, ParentFP,
1732 llvm::ConstantInt::get(Int32Ty, FrameEscapeIdx)});
1735 // If the parent didn't have an alloca, we're doing some nested outlining.
1736 // Just clone the existing localrecover call, but tweak the FP argument to
1737 // use our FP value. All other arguments are constants.
1738 auto *ParentRecover =
1739 cast<llvm::IntrinsicInst>(ParentVar.getPointer()->stripPointerCasts());
1740 assert(ParentRecover->getIntrinsicID() == llvm::Intrinsic::localrecover &&
1741 "expected alloca or localrecover in parent LocalDeclMap");
1742 RecoverCall = cast<llvm::CallInst>(ParentRecover->clone());
1743 RecoverCall->setArgOperand(1, ParentFP);
1744 RecoverCall->insertBefore(AllocaInsertPt);
1747 // Bitcast the variable, rename it, and insert it in the local decl map.
1748 llvm::Value *ChildVar =
1749 Builder.CreateBitCast(RecoverCall, ParentVar.getType());
1750 ChildVar->setName(ParentVar.getName());
1751 return Address(ChildVar, ParentVar.getAlignment());
1754 void CodeGenFunction::EmitCapturedLocals(CodeGenFunction &ParentCGF,
1755 const Stmt *OutlinedStmt,
1757 // Find all captures in the Stmt.
1758 CaptureFinder Finder(ParentCGF, ParentCGF.CXXABIThisDecl);
1759 Finder.Visit(OutlinedStmt);
1761 // We can exit early on x86_64 when there are no captures. We just have to
1762 // save the exception code in filters so that __exception_code() works.
1763 if (!Finder.foundCaptures() &&
1764 CGM.getTarget().getTriple().getArch() != llvm::Triple::x86) {
1766 EmitSEHExceptionCodeSave(ParentCGF, nullptr, nullptr);
1770 llvm::Value *EntryFP = nullptr;
1771 CGBuilderTy Builder(CGM, AllocaInsertPt);
1772 if (IsFilter && CGM.getTarget().getTriple().getArch() == llvm::Triple::x86) {
1773 // 32-bit SEH filters need to be careful about FP recovery. The end of the
1774 // EH registration is passed in as the EBP physical register. We can
1775 // recover that with llvm.frameaddress(1).
1776 EntryFP = Builder.CreateCall(
1777 CGM.getIntrinsic(llvm::Intrinsic::frameaddress), {Builder.getInt32(1)});
1779 // Otherwise, for x64 and 32-bit finally functions, the parent FP is the
1780 // second parameter.
1781 auto AI = CurFn->arg_begin();
1786 llvm::Value *ParentFP = EntryFP;
1788 // Given whatever FP the runtime provided us in EntryFP, recover the true
1789 // frame pointer of the parent function. We only need to do this in filters,
1790 // since finally funclets recover the parent FP for us.
1791 llvm::Function *RecoverFPIntrin =
1792 CGM.getIntrinsic(llvm::Intrinsic::eh_recoverfp);
1793 llvm::Constant *ParentI8Fn =
1794 llvm::ConstantExpr::getBitCast(ParentCGF.CurFn, Int8PtrTy);
1795 ParentFP = Builder.CreateCall(RecoverFPIntrin, {ParentI8Fn, EntryFP});
1798 // Create llvm.localrecover calls for all captures.
1799 for (const VarDecl *VD : Finder.Captures) {
1800 if (isa<ImplicitParamDecl>(VD)) {
1801 CGM.ErrorUnsupported(VD, "'this' captured by SEH");
1802 CXXThisValue = llvm::UndefValue::get(ConvertTypeForMem(VD->getType()));
1805 if (VD->getType()->isVariablyModifiedType()) {
1806 CGM.ErrorUnsupported(VD, "VLA captured by SEH");
1809 assert((isa<ImplicitParamDecl>(VD) || VD->isLocalVarDeclOrParm()) &&
1810 "captured non-local variable");
1812 // If this decl hasn't been declared yet, it will be declared in the
1814 auto I = ParentCGF.LocalDeclMap.find(VD);
1815 if (I == ParentCGF.LocalDeclMap.end())
1818 Address ParentVar = I->second;
1820 VD, recoverAddrOfEscapedLocal(ParentCGF, ParentVar, ParentFP));
1823 if (Finder.SEHCodeSlot.isValid()) {
1824 SEHCodeSlotStack.push_back(
1825 recoverAddrOfEscapedLocal(ParentCGF, Finder.SEHCodeSlot, ParentFP));
1829 EmitSEHExceptionCodeSave(ParentCGF, ParentFP, EntryFP);
1832 /// Arrange a function prototype that can be called by Windows exception
1833 /// handling personalities. On Win64, the prototype looks like:
1834 /// RetTy func(void *EHPtrs, void *ParentFP);
1835 void CodeGenFunction::startOutlinedSEHHelper(CodeGenFunction &ParentCGF,
1837 const Stmt *OutlinedStmt) {
1838 SourceLocation StartLoc = OutlinedStmt->getBeginLoc();
1840 // Get the mangled function name.
1841 SmallString<128> Name;
1843 llvm::raw_svector_ostream OS(Name);
1844 const NamedDecl *ParentSEHFn = ParentCGF.CurSEHParent;
1845 assert(ParentSEHFn && "No CurSEHParent!");
1846 MangleContext &Mangler = CGM.getCXXABI().getMangleContext();
1848 Mangler.mangleSEHFilterExpression(ParentSEHFn, OS);
1850 Mangler.mangleSEHFinallyBlock(ParentSEHFn, OS);
1853 FunctionArgList Args;
1854 if (CGM.getTarget().getTriple().getArch() != llvm::Triple::x86 || !IsFilter) {
1855 // All SEH finally functions take two parameters. Win64 filters take two
1856 // parameters. Win32 filters take no parameters.
1858 Args.push_back(ImplicitParamDecl::Create(
1859 getContext(), /*DC=*/nullptr, StartLoc,
1860 &getContext().Idents.get("exception_pointers"),
1861 getContext().VoidPtrTy, ImplicitParamDecl::Other));
1863 Args.push_back(ImplicitParamDecl::Create(
1864 getContext(), /*DC=*/nullptr, StartLoc,
1865 &getContext().Idents.get("abnormal_termination"),
1866 getContext().UnsignedCharTy, ImplicitParamDecl::Other));
1868 Args.push_back(ImplicitParamDecl::Create(
1869 getContext(), /*DC=*/nullptr, StartLoc,
1870 &getContext().Idents.get("frame_pointer"), getContext().VoidPtrTy,
1871 ImplicitParamDecl::Other));
1874 QualType RetTy = IsFilter ? getContext().LongTy : getContext().VoidTy;
1876 const CGFunctionInfo &FnInfo =
1877 CGM.getTypes().arrangeBuiltinFunctionDeclaration(RetTy, Args);
1879 llvm::FunctionType *FnTy = CGM.getTypes().GetFunctionType(FnInfo);
1880 llvm::Function *Fn = llvm::Function::Create(
1881 FnTy, llvm::GlobalValue::InternalLinkage, Name.str(), &CGM.getModule());
1883 IsOutlinedSEHHelper = true;
1885 StartFunction(GlobalDecl(), RetTy, Fn, FnInfo, Args,
1886 OutlinedStmt->getBeginLoc(), OutlinedStmt->getBeginLoc());
1887 CurSEHParent = ParentCGF.CurSEHParent;
1889 CGM.SetLLVMFunctionAttributes(GlobalDecl(), FnInfo, CurFn);
1890 EmitCapturedLocals(ParentCGF, OutlinedStmt, IsFilter);
1893 /// Create a stub filter function that will ultimately hold the code of the
1894 /// filter expression. The EH preparation passes in LLVM will outline the code
1895 /// from the main function body into this stub.
1897 CodeGenFunction::GenerateSEHFilterFunction(CodeGenFunction &ParentCGF,
1898 const SEHExceptStmt &Except) {
1899 const Expr *FilterExpr = Except.getFilterExpr();
1900 startOutlinedSEHHelper(ParentCGF, true, FilterExpr);
1902 // Emit the original filter expression, convert to i32, and return.
1903 llvm::Value *R = EmitScalarExpr(FilterExpr);
1904 R = Builder.CreateIntCast(R, ConvertType(getContext().LongTy),
1905 FilterExpr->getType()->isSignedIntegerType());
1906 Builder.CreateStore(R, ReturnValue);
1908 FinishFunction(FilterExpr->getEndLoc());
1914 CodeGenFunction::GenerateSEHFinallyFunction(CodeGenFunction &ParentCGF,
1915 const SEHFinallyStmt &Finally) {
1916 const Stmt *FinallyBlock = Finally.getBlock();
1917 startOutlinedSEHHelper(ParentCGF, false, FinallyBlock);
1919 // Emit the original filter expression, convert to i32, and return.
1920 EmitStmt(FinallyBlock);
1922 FinishFunction(FinallyBlock->getEndLoc());
1927 void CodeGenFunction::EmitSEHExceptionCodeSave(CodeGenFunction &ParentCGF,
1928 llvm::Value *ParentFP,
1929 llvm::Value *EntryFP) {
1930 // Get the pointer to the EXCEPTION_POINTERS struct. This is returned by the
1931 // __exception_info intrinsic.
1932 if (CGM.getTarget().getTriple().getArch() != llvm::Triple::x86) {
1933 // On Win64, the info is passed as the first parameter to the filter.
1934 SEHInfo = &*CurFn->arg_begin();
1935 SEHCodeSlotStack.push_back(
1936 CreateMemTemp(getContext().IntTy, "__exception_code"));
1938 // On Win32, the EBP on entry to the filter points to the end of an
1939 // exception registration object. It contains 6 32-bit fields, and the info
1940 // pointer is stored in the second field. So, GEP 20 bytes backwards and
1941 // load the pointer.
1942 SEHInfo = Builder.CreateConstInBoundsGEP1_32(Int8Ty, EntryFP, -20);
1943 SEHInfo = Builder.CreateBitCast(SEHInfo, Int8PtrTy->getPointerTo());
1944 SEHInfo = Builder.CreateAlignedLoad(Int8PtrTy, SEHInfo, getPointerAlign());
1945 SEHCodeSlotStack.push_back(recoverAddrOfEscapedLocal(
1946 ParentCGF, ParentCGF.SEHCodeSlotStack.back(), ParentFP));
1949 // Save the exception code in the exception slot to unify exception access in
1950 // the filter function and the landing pad.
1951 // struct EXCEPTION_POINTERS {
1952 // EXCEPTION_RECORD *ExceptionRecord;
1953 // CONTEXT *ContextRecord;
1955 // int exceptioncode = exception_pointers->ExceptionRecord->ExceptionCode;
1956 llvm::Type *RecordTy = CGM.Int32Ty->getPointerTo();
1957 llvm::Type *PtrsTy = llvm::StructType::get(RecordTy, CGM.VoidPtrTy);
1958 llvm::Value *Ptrs = Builder.CreateBitCast(SEHInfo, PtrsTy->getPointerTo());
1959 llvm::Value *Rec = Builder.CreateStructGEP(PtrsTy, Ptrs, 0);
1960 Rec = Builder.CreateAlignedLoad(Rec, getPointerAlign());
1961 llvm::Value *Code = Builder.CreateAlignedLoad(Rec, getIntAlign());
1962 assert(!SEHCodeSlotStack.empty() && "emitting EH code outside of __except");
1963 Builder.CreateStore(Code, SEHCodeSlotStack.back());
1966 llvm::Value *CodeGenFunction::EmitSEHExceptionInfo() {
1967 // Sema should diagnose calling this builtin outside of a filter context, but
1968 // don't crash if we screw up.
1970 return llvm::UndefValue::get(Int8PtrTy);
1971 assert(SEHInfo->getType() == Int8PtrTy);
1975 llvm::Value *CodeGenFunction::EmitSEHExceptionCode() {
1976 assert(!SEHCodeSlotStack.empty() && "emitting EH code outside of __except");
1977 return Builder.CreateLoad(SEHCodeSlotStack.back());
1980 llvm::Value *CodeGenFunction::EmitSEHAbnormalTermination() {
1981 // Abnormal termination is just the first parameter to the outlined finally
1983 auto AI = CurFn->arg_begin();
1984 return Builder.CreateZExt(&*AI, Int32Ty);
1987 void CodeGenFunction::pushSEHCleanup(CleanupKind Kind,
1988 llvm::Function *FinallyFunc) {
1989 EHStack.pushCleanup<PerformSEHFinally>(Kind, FinallyFunc);
1992 void CodeGenFunction::EnterSEHTryStmt(const SEHTryStmt &S) {
1993 CodeGenFunction HelperCGF(CGM, /*suppressNewContext=*/true);
1994 if (const SEHFinallyStmt *Finally = S.getFinallyHandler()) {
1995 // Outline the finally block.
1996 llvm::Function *FinallyFunc =
1997 HelperCGF.GenerateSEHFinallyFunction(*this, *Finally);
1999 // Push a cleanup for __finally blocks.
2000 EHStack.pushCleanup<PerformSEHFinally>(NormalAndEHCleanup, FinallyFunc);
2004 // Otherwise, we must have an __except block.
2005 const SEHExceptStmt *Except = S.getExceptHandler();
2007 EHCatchScope *CatchScope = EHStack.pushCatch(1);
2008 SEHCodeSlotStack.push_back(
2009 CreateMemTemp(getContext().IntTy, "__exception_code"));
2011 // If the filter is known to evaluate to 1, then we can use the clause
2012 // "catch i8* null". We can't do this on x86 because the filter has to save
2013 // the exception code.
2015 ConstantEmitter(*this).tryEmitAbstract(Except->getFilterExpr(),
2016 getContext().IntTy);
2017 if (CGM.getTarget().getTriple().getArch() != llvm::Triple::x86 && C &&
2019 CatchScope->setCatchAllHandler(0, createBasicBlock("__except"));
2023 // In general, we have to emit an outlined filter function. Use the function
2024 // in place of the RTTI typeinfo global that C++ EH uses.
2025 llvm::Function *FilterFunc =
2026 HelperCGF.GenerateSEHFilterFunction(*this, *Except);
2027 llvm::Constant *OpaqueFunc =
2028 llvm::ConstantExpr::getBitCast(FilterFunc, Int8PtrTy);
2029 CatchScope->setHandler(0, OpaqueFunc, createBasicBlock("__except.ret"));
2032 void CodeGenFunction::ExitSEHTryStmt(const SEHTryStmt &S) {
2033 // Just pop the cleanup if it's a __finally block.
2034 if (S.getFinallyHandler()) {
2039 // Otherwise, we must have an __except block.
2040 const SEHExceptStmt *Except = S.getExceptHandler();
2041 assert(Except && "__try must have __finally xor __except");
2042 EHCatchScope &CatchScope = cast<EHCatchScope>(*EHStack.begin());
2044 // Don't emit the __except block if the __try block lacked invokes.
2045 // TODO: Model unwind edges from instructions, either with iload / istore or
2046 // a try body function.
2047 if (!CatchScope.hasEHBranches()) {
2048 CatchScope.clearHandlerBlocks();
2050 SEHCodeSlotStack.pop_back();
2054 // The fall-through block.
2055 llvm::BasicBlock *ContBB = createBasicBlock("__try.cont");
2057 // We just emitted the body of the __try; jump to the continue block.
2058 if (HaveInsertPoint())
2059 Builder.CreateBr(ContBB);
2061 // Check if our filter function returned true.
2062 emitCatchDispatchBlock(*this, CatchScope);
2064 // Grab the block before we pop the handler.
2065 llvm::BasicBlock *CatchPadBB = CatchScope.getHandler(0).Block;
2068 EmitBlockAfterUses(CatchPadBB);
2070 // __except blocks don't get outlined into funclets, so immediately do a
2072 llvm::CatchPadInst *CPI =
2073 cast<llvm::CatchPadInst>(CatchPadBB->getFirstNonPHI());
2074 llvm::BasicBlock *ExceptBB = createBasicBlock("__except");
2075 Builder.CreateCatchRet(CPI, ExceptBB);
2076 EmitBlock(ExceptBB);
2078 // On Win64, the exception code is returned in EAX. Copy it into the slot.
2079 if (CGM.getTarget().getTriple().getArch() != llvm::Triple::x86) {
2080 llvm::Function *SEHCodeIntrin =
2081 CGM.getIntrinsic(llvm::Intrinsic::eh_exceptioncode);
2082 llvm::Value *Code = Builder.CreateCall(SEHCodeIntrin, {CPI});
2083 Builder.CreateStore(Code, SEHCodeSlotStack.back());
2086 // Emit the __except body.
2087 EmitStmt(Except->getBlock());
2089 // End the lifetime of the exception code.
2090 SEHCodeSlotStack.pop_back();
2092 if (HaveInsertPoint())
2093 Builder.CreateBr(ContBB);
2098 void CodeGenFunction::EmitSEHLeaveStmt(const SEHLeaveStmt &S) {
2099 // If this code is reachable then emit a stop point (if generating
2100 // debug info). We have to do this ourselves because we are on the
2101 // "simple" statement path.
2102 if (HaveInsertPoint())
2105 // This must be a __leave from a __finally block, which we warn on and is UB.
2106 // Just emit unreachable.
2107 if (!isSEHTryScope()) {
2108 Builder.CreateUnreachable();
2109 Builder.ClearInsertionPoint();
2113 EmitBranchThroughCleanup(*SEHTryEpilogueStack.back());