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 //===----------------------------------------------------------------------===//
14 #include "CGCleanup.h"
15 #include "CGObjCRuntime.h"
16 #include "CodeGenFunction.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/DiagnosticSema.h"
24 #include "clang/Basic/TargetBuiltins.h"
25 #include "llvm/IR/IntrinsicInst.h"
26 #include "llvm/IR/Intrinsics.h"
27 #include "llvm/IR/IntrinsicsWebAssembly.h"
28 #include "llvm/Support/SaveAndRestore.h"
30 using namespace clang;
31 using namespace CodeGen;
33 static llvm::FunctionCallee getFreeExceptionFn(CodeGenModule &CGM) {
34 // void __cxa_free_exception(void *thrown_exception);
36 llvm::FunctionType *FTy =
37 llvm::FunctionType::get(CGM.VoidTy, CGM.Int8PtrTy, /*isVarArg=*/false);
39 return CGM.CreateRuntimeFunction(FTy, "__cxa_free_exception");
42 static llvm::FunctionCallee getUnexpectedFn(CodeGenModule &CGM) {
43 // void __cxa_call_unexpected(void *thrown_exception);
45 llvm::FunctionType *FTy =
46 llvm::FunctionType::get(CGM.VoidTy, CGM.Int8PtrTy, /*isVarArg=*/false);
48 return CGM.CreateRuntimeFunction(FTy, "__cxa_call_unexpected");
51 llvm::FunctionCallee CodeGenModule::getTerminateFn() {
52 // void __terminate();
54 llvm::FunctionType *FTy =
55 llvm::FunctionType::get(VoidTy, /*isVarArg=*/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 = "?terminate@@YAXXZ";
69 } else if (getLangOpts().ObjC &&
70 getLangOpts().ObjCRuntime.hasTerminate())
71 name = "objc_terminate";
74 return CreateRuntimeFunction(FTy, name);
77 static llvm::FunctionCallee getCatchallRethrowFn(CodeGenModule &CGM,
79 llvm::FunctionType *FTy =
80 llvm::FunctionType::get(CGM.VoidTy, CGM.Int8PtrTy, /*isVarArg=*/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 EHPersonality::GNU_Wasm_CPlusPlus = { "__gxx_wasm_personality_v0", nullptr };
117 static const EHPersonality &getCPersonality(const TargetInfo &Target,
118 const LangOptions &L) {
119 const llvm::Triple &T = Target.getTriple();
120 if (T.isWindowsMSVCEnvironment())
121 return EHPersonality::MSVC_CxxFrameHandler3;
122 if (L.SjLjExceptions)
123 return EHPersonality::GNU_C_SJLJ;
124 if (L.DWARFExceptions)
125 return EHPersonality::GNU_C;
127 return EHPersonality::GNU_C_SEH;
128 return EHPersonality::GNU_C;
131 static const EHPersonality &getObjCPersonality(const TargetInfo &Target,
132 const LangOptions &L) {
133 const llvm::Triple &T = Target.getTriple();
134 if (T.isWindowsMSVCEnvironment())
135 return EHPersonality::MSVC_CxxFrameHandler3;
137 switch (L.ObjCRuntime.getKind()) {
138 case ObjCRuntime::FragileMacOSX:
139 return getCPersonality(Target, L);
140 case ObjCRuntime::MacOSX:
141 case ObjCRuntime::iOS:
142 case ObjCRuntime::WatchOS:
143 return EHPersonality::NeXT_ObjC;
144 case ObjCRuntime::GNUstep:
145 if (L.ObjCRuntime.getVersion() >= VersionTuple(1, 7))
146 return EHPersonality::GNUstep_ObjC;
148 case ObjCRuntime::GCC:
149 case ObjCRuntime::ObjFW:
150 if (L.SjLjExceptions)
151 return EHPersonality::GNU_ObjC_SJLJ;
153 return EHPersonality::GNU_ObjC_SEH;
154 return EHPersonality::GNU_ObjC;
156 llvm_unreachable("bad runtime kind");
159 static const EHPersonality &getCXXPersonality(const TargetInfo &Target,
160 const LangOptions &L) {
161 const llvm::Triple &T = Target.getTriple();
162 if (T.isWindowsMSVCEnvironment())
163 return EHPersonality::MSVC_CxxFrameHandler3;
164 if (L.SjLjExceptions)
165 return EHPersonality::GNU_CPlusPlus_SJLJ;
166 if (L.DWARFExceptions)
167 return EHPersonality::GNU_CPlusPlus;
169 return EHPersonality::GNU_CPlusPlus_SEH;
170 if (L.WasmExceptions)
171 return EHPersonality::GNU_Wasm_CPlusPlus;
172 return EHPersonality::GNU_CPlusPlus;
175 /// Determines the personality function to use when both C++
176 /// and Objective-C exceptions are being caught.
177 static const EHPersonality &getObjCXXPersonality(const TargetInfo &Target,
178 const LangOptions &L) {
179 if (Target.getTriple().isWindowsMSVCEnvironment())
180 return EHPersonality::MSVC_CxxFrameHandler3;
182 switch (L.ObjCRuntime.getKind()) {
183 // In the fragile ABI, just use C++ exception handling and hope
184 // they're not doing crazy exception mixing.
185 case ObjCRuntime::FragileMacOSX:
186 return getCXXPersonality(Target, L);
188 // The ObjC personality defers to the C++ personality for non-ObjC
189 // handlers. Unlike the C++ case, we use the same personality
190 // function on targets using (backend-driven) SJLJ EH.
191 case ObjCRuntime::MacOSX:
192 case ObjCRuntime::iOS:
193 case ObjCRuntime::WatchOS:
194 return getObjCPersonality(Target, L);
196 case ObjCRuntime::GNUstep:
197 return EHPersonality::GNU_ObjCXX;
199 // The GCC runtime's personality function inherently doesn't support
200 // mixed EH. Use the ObjC personality just to avoid returning null.
201 case ObjCRuntime::GCC:
202 case ObjCRuntime::ObjFW:
203 return getObjCPersonality(Target, L);
205 llvm_unreachable("bad runtime kind");
208 static const EHPersonality &getSEHPersonalityMSVC(const llvm::Triple &T) {
209 if (T.getArch() == llvm::Triple::x86)
210 return EHPersonality::MSVC_except_handler;
211 return EHPersonality::MSVC_C_specific_handler;
214 const EHPersonality &EHPersonality::get(CodeGenModule &CGM,
215 const FunctionDecl *FD) {
216 const llvm::Triple &T = CGM.getTarget().getTriple();
217 const LangOptions &L = CGM.getLangOpts();
218 const TargetInfo &Target = CGM.getTarget();
220 // Functions using SEH get an SEH personality.
221 if (FD && FD->usesSEHTry())
222 return getSEHPersonalityMSVC(T);
225 return L.CPlusPlus ? getObjCXXPersonality(Target, L)
226 : getObjCPersonality(Target, L);
227 return L.CPlusPlus ? getCXXPersonality(Target, L)
228 : getCPersonality(Target, L);
231 const EHPersonality &EHPersonality::get(CodeGenFunction &CGF) {
232 const auto *FD = CGF.CurCodeDecl;
233 // For outlined finallys and filters, use the SEH personality in case they
234 // contain more SEH. This mostly only affects finallys. Filters could
235 // hypothetically use gnu statement expressions to sneak in nested SEH.
236 FD = FD ? FD : CGF.CurSEHParent;
237 return get(CGF.CGM, dyn_cast_or_null<FunctionDecl>(FD));
240 static llvm::FunctionCallee getPersonalityFn(CodeGenModule &CGM,
241 const EHPersonality &Personality) {
242 return CGM.CreateRuntimeFunction(llvm::FunctionType::get(CGM.Int32Ty, true),
243 Personality.PersonalityFn,
244 llvm::AttributeList(), /*Local=*/true);
247 static llvm::Constant *getOpaquePersonalityFn(CodeGenModule &CGM,
248 const EHPersonality &Personality) {
249 llvm::FunctionCallee Fn = getPersonalityFn(CGM, Personality);
250 llvm::PointerType* Int8PtrTy = llvm::PointerType::get(
251 llvm::Type::getInt8Ty(CGM.getLLVMContext()),
252 CGM.getDataLayout().getProgramAddressSpace());
254 return llvm::ConstantExpr::getBitCast(cast<llvm::Constant>(Fn.getCallee()),
258 /// Check whether a landingpad instruction only uses C++ features.
259 static bool LandingPadHasOnlyCXXUses(llvm::LandingPadInst *LPI) {
260 for (unsigned I = 0, E = LPI->getNumClauses(); I != E; ++I) {
261 // Look for something that would've been returned by the ObjC
262 // runtime's GetEHType() method.
263 llvm::Value *Val = LPI->getClause(I)->stripPointerCasts();
264 if (LPI->isCatch(I)) {
265 // Check if the catch value has the ObjC prefix.
266 if (llvm::GlobalVariable *GV = dyn_cast<llvm::GlobalVariable>(Val))
267 // ObjC EH selector entries are always global variables with
268 // names starting like this.
269 if (GV->getName().startswith("OBJC_EHTYPE"))
272 // Check if any of the filter values have the ObjC prefix.
273 llvm::Constant *CVal = cast<llvm::Constant>(Val);
274 for (llvm::User::op_iterator
275 II = CVal->op_begin(), IE = CVal->op_end(); II != IE; ++II) {
276 if (llvm::GlobalVariable *GV =
277 cast<llvm::GlobalVariable>((*II)->stripPointerCasts()))
278 // ObjC EH selector entries are always global variables with
279 // names starting like this.
280 if (GV->getName().startswith("OBJC_EHTYPE"))
288 /// Check whether a personality function could reasonably be swapped
289 /// for a C++ personality function.
290 static bool PersonalityHasOnlyCXXUses(llvm::Constant *Fn) {
291 for (llvm::User *U : Fn->users()) {
292 // Conditionally white-list bitcasts.
293 if (llvm::ConstantExpr *CE = dyn_cast<llvm::ConstantExpr>(U)) {
294 if (CE->getOpcode() != llvm::Instruction::BitCast) return false;
295 if (!PersonalityHasOnlyCXXUses(CE))
300 // Otherwise it must be a function.
301 llvm::Function *F = dyn_cast<llvm::Function>(U);
302 if (!F) return false;
304 for (auto BB = F->begin(), E = F->end(); BB != E; ++BB) {
305 if (BB->isLandingPad())
306 if (!LandingPadHasOnlyCXXUses(BB->getLandingPadInst()))
314 /// Try to use the C++ personality function in ObjC++. Not doing this
315 /// can cause some incompatibilities with gcc, which is more
316 /// aggressive about only using the ObjC++ personality in a function
317 /// when it really needs it.
318 void CodeGenModule::SimplifyPersonality() {
319 // If we're not in ObjC++ -fexceptions, there's nothing to do.
320 if (!LangOpts.CPlusPlus || !LangOpts.ObjC || !LangOpts.Exceptions)
323 // Both the problem this endeavors to fix and the way the logic
324 // above works is specific to the NeXT runtime.
325 if (!LangOpts.ObjCRuntime.isNeXTFamily())
328 const EHPersonality &ObjCXX = EHPersonality::get(*this, /*FD=*/nullptr);
329 const EHPersonality &CXX = getCXXPersonality(getTarget(), LangOpts);
333 assert(std::strcmp(ObjCXX.PersonalityFn, CXX.PersonalityFn) != 0 &&
334 "Different EHPersonalities using the same personality function.");
336 llvm::Function *Fn = getModule().getFunction(ObjCXX.PersonalityFn);
338 // Nothing to do if it's unused.
339 if (!Fn || Fn->use_empty()) return;
341 // Can't do the optimization if it has non-C++ uses.
342 if (!PersonalityHasOnlyCXXUses(Fn)) return;
344 // Create the C++ personality function and kill off the old
346 llvm::FunctionCallee CXXFn = getPersonalityFn(*this, CXX);
348 // This can happen if the user is screwing with us.
349 if (Fn->getType() != CXXFn.getCallee()->getType())
352 Fn->replaceAllUsesWith(CXXFn.getCallee());
353 Fn->eraseFromParent();
356 /// Returns the value to inject into a selector to indicate the
357 /// presence of a catch-all.
358 static llvm::Constant *getCatchAllValue(CodeGenFunction &CGF) {
359 // Possibly we should use @llvm.eh.catch.all.value here.
360 return llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
364 /// A cleanup to free the exception object if its initialization
366 struct FreeException final : EHScopeStack::Cleanup {
368 FreeException(llvm::Value *exn) : exn(exn) {}
369 void Emit(CodeGenFunction &CGF, Flags flags) override {
370 CGF.EmitNounwindRuntimeCall(getFreeExceptionFn(CGF.CGM), exn);
373 } // end anonymous namespace
375 // Emits an exception expression into the given location. This
376 // differs from EmitAnyExprToMem only in that, if a final copy-ctor
377 // call is required, an exception within that copy ctor causes
378 // std::terminate to be invoked.
379 void CodeGenFunction::EmitAnyExprToExn(const Expr *e, Address addr) {
380 // Make sure the exception object is cleaned up if there's an
381 // exception during initialization.
382 pushFullExprCleanup<FreeException>(EHCleanup, addr.getPointer());
383 EHScopeStack::stable_iterator cleanup = EHStack.stable_begin();
385 // __cxa_allocate_exception returns a void*; we need to cast this
386 // to the appropriate type for the object.
387 llvm::Type *ty = ConvertTypeForMem(e->getType())->getPointerTo();
388 Address typedAddr = Builder.CreateBitCast(addr, ty);
390 // FIXME: this isn't quite right! If there's a final unelided call
391 // to a copy constructor, then according to [except.terminate]p1 we
392 // must call std::terminate() if that constructor throws, because
393 // technically that copy occurs after the exception expression is
394 // evaluated but before the exception is caught. But the best way
395 // to handle that is to teach EmitAggExpr to do the final copy
396 // differently if it can't be elided.
397 EmitAnyExprToMem(e, typedAddr, e->getType().getQualifiers(),
400 // Deactivate the cleanup block.
401 DeactivateCleanupBlock(cleanup,
402 cast<llvm::Instruction>(typedAddr.getPointer()));
405 Address CodeGenFunction::getExceptionSlot() {
407 ExceptionSlot = CreateTempAlloca(Int8PtrTy, "exn.slot");
408 return Address(ExceptionSlot, getPointerAlign());
411 Address CodeGenFunction::getEHSelectorSlot() {
413 EHSelectorSlot = CreateTempAlloca(Int32Ty, "ehselector.slot");
414 return Address(EHSelectorSlot, CharUnits::fromQuantity(4));
417 llvm::Value *CodeGenFunction::getExceptionFromSlot() {
418 return Builder.CreateLoad(getExceptionSlot(), "exn");
421 llvm::Value *CodeGenFunction::getSelectorFromSlot() {
422 return Builder.CreateLoad(getEHSelectorSlot(), "sel");
425 void CodeGenFunction::EmitCXXThrowExpr(const CXXThrowExpr *E,
426 bool KeepInsertionPoint) {
427 if (const Expr *SubExpr = E->getSubExpr()) {
428 QualType ThrowType = SubExpr->getType();
429 if (ThrowType->isObjCObjectPointerType()) {
430 const Stmt *ThrowStmt = E->getSubExpr();
431 const ObjCAtThrowStmt S(E->getExprLoc(), const_cast<Stmt *>(ThrowStmt));
432 CGM.getObjCRuntime().EmitThrowStmt(*this, S, false);
434 CGM.getCXXABI().emitThrow(*this, E);
437 CGM.getCXXABI().emitRethrow(*this, /*isNoReturn=*/true);
440 // throw is an expression, and the expression emitters expect us
441 // to leave ourselves at a valid insertion point.
442 if (KeepInsertionPoint)
443 EmitBlock(createBasicBlock("throw.cont"));
446 void CodeGenFunction::EmitStartEHSpec(const Decl *D) {
447 if (!CGM.getLangOpts().CXXExceptions)
450 const FunctionDecl* FD = dyn_cast_or_null<FunctionDecl>(D);
452 // Check if CapturedDecl is nothrow and create terminate scope for it.
453 if (const CapturedDecl* CD = dyn_cast_or_null<CapturedDecl>(D)) {
455 EHStack.pushTerminate();
459 const FunctionProtoType *Proto = FD->getType()->getAs<FunctionProtoType>();
463 ExceptionSpecificationType EST = Proto->getExceptionSpecType();
464 if (isNoexceptExceptionSpec(EST) && Proto->canThrow() == CT_Cannot) {
465 // noexcept functions are simple terminate scopes.
466 EHStack.pushTerminate();
467 } else if (EST == EST_Dynamic || EST == EST_DynamicNone) {
468 // TODO: Revisit exception specifications for the MS ABI. There is a way to
469 // encode these in an object file but MSVC doesn't do anything with it.
470 if (getTarget().getCXXABI().isMicrosoft())
472 // In wasm we currently treat 'throw()' in the same way as 'noexcept'. In
473 // case of throw with types, we ignore it and print a warning for now.
474 // TODO Correctly handle exception specification in wasm
475 if (CGM.getLangOpts().WasmExceptions) {
476 if (EST == EST_DynamicNone)
477 EHStack.pushTerminate();
479 CGM.getDiags().Report(D->getLocation(),
480 diag::warn_wasm_dynamic_exception_spec_ignored)
481 << FD->getExceptionSpecSourceRange();
484 unsigned NumExceptions = Proto->getNumExceptions();
485 EHFilterScope *Filter = EHStack.pushFilter(NumExceptions);
487 for (unsigned I = 0; I != NumExceptions; ++I) {
488 QualType Ty = Proto->getExceptionType(I);
489 QualType ExceptType = Ty.getNonReferenceType().getUnqualifiedType();
490 llvm::Value *EHType = CGM.GetAddrOfRTTIDescriptor(ExceptType,
492 Filter->setFilter(I, EHType);
497 /// Emit the dispatch block for a filter scope if necessary.
498 static void emitFilterDispatchBlock(CodeGenFunction &CGF,
499 EHFilterScope &filterScope) {
500 llvm::BasicBlock *dispatchBlock = filterScope.getCachedEHDispatchBlock();
501 if (!dispatchBlock) return;
502 if (dispatchBlock->use_empty()) {
503 delete dispatchBlock;
507 CGF.EmitBlockAfterUses(dispatchBlock);
509 // If this isn't a catch-all filter, we need to check whether we got
510 // here because the filter triggered.
511 if (filterScope.getNumFilters()) {
512 // Load the selector value.
513 llvm::Value *selector = CGF.getSelectorFromSlot();
514 llvm::BasicBlock *unexpectedBB = CGF.createBasicBlock("ehspec.unexpected");
516 llvm::Value *zero = CGF.Builder.getInt32(0);
517 llvm::Value *failsFilter =
518 CGF.Builder.CreateICmpSLT(selector, zero, "ehspec.fails");
519 CGF.Builder.CreateCondBr(failsFilter, unexpectedBB,
520 CGF.getEHResumeBlock(false));
522 CGF.EmitBlock(unexpectedBB);
525 // Call __cxa_call_unexpected. This doesn't need to be an invoke
526 // because __cxa_call_unexpected magically filters exceptions
527 // according to the last landing pad the exception was thrown
529 llvm::Value *exn = CGF.getExceptionFromSlot();
530 CGF.EmitRuntimeCall(getUnexpectedFn(CGF.CGM), exn)
531 ->setDoesNotReturn();
532 CGF.Builder.CreateUnreachable();
535 void CodeGenFunction::EmitEndEHSpec(const Decl *D) {
536 if (!CGM.getLangOpts().CXXExceptions)
539 const FunctionDecl* FD = dyn_cast_or_null<FunctionDecl>(D);
541 // Check if CapturedDecl is nothrow and pop terminate scope for it.
542 if (const CapturedDecl* CD = dyn_cast_or_null<CapturedDecl>(D)) {
544 EHStack.popTerminate();
548 const FunctionProtoType *Proto = FD->getType()->getAs<FunctionProtoType>();
552 ExceptionSpecificationType EST = Proto->getExceptionSpecType();
553 if (isNoexceptExceptionSpec(EST) && Proto->canThrow() == CT_Cannot) {
554 EHStack.popTerminate();
555 } else if (EST == EST_Dynamic || EST == EST_DynamicNone) {
556 // TODO: Revisit exception specifications for the MS ABI. There is a way to
557 // encode these in an object file but MSVC doesn't do anything with it.
558 if (getTarget().getCXXABI().isMicrosoft())
560 // In wasm we currently treat 'throw()' in the same way as 'noexcept'. In
561 // case of throw with types, we ignore it and print a warning for now.
562 // TODO Correctly handle exception specification in wasm
563 if (CGM.getLangOpts().WasmExceptions) {
564 if (EST == EST_DynamicNone)
565 EHStack.popTerminate();
568 EHFilterScope &filterScope = cast<EHFilterScope>(*EHStack.begin());
569 emitFilterDispatchBlock(*this, filterScope);
574 void CodeGenFunction::EmitCXXTryStmt(const CXXTryStmt &S) {
576 EmitStmt(S.getTryBlock());
580 void CodeGenFunction::EnterCXXTryStmt(const CXXTryStmt &S, bool IsFnTryBlock) {
581 unsigned NumHandlers = S.getNumHandlers();
582 EHCatchScope *CatchScope = EHStack.pushCatch(NumHandlers);
584 for (unsigned I = 0; I != NumHandlers; ++I) {
585 const CXXCatchStmt *C = S.getHandler(I);
587 llvm::BasicBlock *Handler = createBasicBlock("catch");
588 if (C->getExceptionDecl()) {
589 // FIXME: Dropping the reference type on the type into makes it
590 // impossible to correctly implement catch-by-reference
591 // semantics for pointers. Unfortunately, this is what all
592 // existing compilers do, and it's not clear that the standard
593 // personality routine is capable of doing this right. See C++ DR 388:
594 // http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#388
595 Qualifiers CaughtTypeQuals;
596 QualType CaughtType = CGM.getContext().getUnqualifiedArrayType(
597 C->getCaughtType().getNonReferenceType(), CaughtTypeQuals);
599 CatchTypeInfo TypeInfo{nullptr, 0};
600 if (CaughtType->isObjCObjectPointerType())
601 TypeInfo.RTTI = CGM.getObjCRuntime().GetEHType(CaughtType);
603 TypeInfo = CGM.getCXXABI().getAddrOfCXXCatchHandlerType(
604 CaughtType, C->getCaughtType());
605 CatchScope->setHandler(I, TypeInfo, Handler);
607 // No exception decl indicates '...', a catch-all.
608 CatchScope->setHandler(I, CGM.getCXXABI().getCatchAllTypeInfo(), Handler);
614 CodeGenFunction::getEHDispatchBlock(EHScopeStack::stable_iterator si) {
615 if (EHPersonality::get(*this).usesFuncletPads())
616 return getFuncletEHDispatchBlock(si);
618 // The dispatch block for the end of the scope chain is a block that
619 // just resumes unwinding.
620 if (si == EHStack.stable_end())
621 return getEHResumeBlock(true);
623 // Otherwise, we should look at the actual scope.
624 EHScope &scope = *EHStack.find(si);
626 llvm::BasicBlock *dispatchBlock = scope.getCachedEHDispatchBlock();
627 if (!dispatchBlock) {
628 switch (scope.getKind()) {
629 case EHScope::Catch: {
630 // Apply a special case to a single catch-all.
631 EHCatchScope &catchScope = cast<EHCatchScope>(scope);
632 if (catchScope.getNumHandlers() == 1 &&
633 catchScope.getHandler(0).isCatchAll()) {
634 dispatchBlock = catchScope.getHandler(0).Block;
636 // Otherwise, make a dispatch block.
638 dispatchBlock = createBasicBlock("catch.dispatch");
643 case EHScope::Cleanup:
644 dispatchBlock = createBasicBlock("ehcleanup");
647 case EHScope::Filter:
648 dispatchBlock = createBasicBlock("filter.dispatch");
651 case EHScope::Terminate:
652 dispatchBlock = getTerminateHandler();
655 scope.setCachedEHDispatchBlock(dispatchBlock);
657 return dispatchBlock;
661 CodeGenFunction::getFuncletEHDispatchBlock(EHScopeStack::stable_iterator SI) {
662 // Returning nullptr indicates that the previous dispatch block should unwind
664 if (SI == EHStack.stable_end())
667 // Otherwise, we should look at the actual scope.
668 EHScope &EHS = *EHStack.find(SI);
670 llvm::BasicBlock *DispatchBlock = EHS.getCachedEHDispatchBlock();
672 return DispatchBlock;
674 if (EHS.getKind() == EHScope::Terminate)
675 DispatchBlock = getTerminateFunclet();
677 DispatchBlock = createBasicBlock();
678 CGBuilderTy Builder(*this, DispatchBlock);
680 switch (EHS.getKind()) {
682 DispatchBlock->setName("catch.dispatch");
685 case EHScope::Cleanup:
686 DispatchBlock->setName("ehcleanup");
689 case EHScope::Filter:
690 llvm_unreachable("exception specifications not handled yet!");
692 case EHScope::Terminate:
693 DispatchBlock->setName("terminate");
696 EHS.setCachedEHDispatchBlock(DispatchBlock);
697 return DispatchBlock;
700 /// Check whether this is a non-EH scope, i.e. a scope which doesn't
701 /// affect exception handling. Currently, the only non-EH scopes are
702 /// normal-only cleanup scopes.
703 static bool isNonEHScope(const EHScope &S) {
704 switch (S.getKind()) {
705 case EHScope::Cleanup:
706 return !cast<EHCleanupScope>(S).isEHCleanup();
707 case EHScope::Filter:
709 case EHScope::Terminate:
713 llvm_unreachable("Invalid EHScope Kind!");
716 llvm::BasicBlock *CodeGenFunction::getInvokeDestImpl() {
717 assert(EHStack.requiresLandingPad());
718 assert(!EHStack.empty());
720 // If exceptions are disabled/ignored and SEH is not in use, then there is no
721 // invoke destination. SEH "works" even if exceptions are off. In practice,
722 // this means that C++ destructors and other EH cleanups don't run, which is
723 // consistent with MSVC's behavior.
724 const LangOptions &LO = CGM.getLangOpts();
725 if (!LO.Exceptions || LO.IgnoreExceptions) {
726 if (!LO.Borland && !LO.MicrosoftExt)
728 if (!currentFunctionUsesSEHTry())
732 // CUDA device code doesn't have exceptions.
733 if (LO.CUDA && LO.CUDAIsDevice)
736 // Check the innermost scope for a cached landing pad. If this is
737 // a non-EH cleanup, we'll check enclosing scopes in EmitLandingPad.
738 llvm::BasicBlock *LP = EHStack.begin()->getCachedLandingPad();
741 const EHPersonality &Personality = EHPersonality::get(*this);
743 if (!CurFn->hasPersonalityFn())
744 CurFn->setPersonalityFn(getOpaquePersonalityFn(CGM, Personality));
746 if (Personality.usesFuncletPads()) {
747 // We don't need separate landing pads in the funclet model.
748 LP = getEHDispatchBlock(EHStack.getInnermostEHScope());
750 // Build the landing pad for this scope.
751 LP = EmitLandingPad();
756 // Cache the landing pad on the innermost scope. If this is a
757 // non-EH scope, cache the landing pad on the enclosing scope, too.
758 for (EHScopeStack::iterator ir = EHStack.begin(); true; ++ir) {
759 ir->setCachedLandingPad(LP);
760 if (!isNonEHScope(*ir)) break;
766 llvm::BasicBlock *CodeGenFunction::EmitLandingPad() {
767 assert(EHStack.requiresLandingPad());
768 assert(!CGM.getLangOpts().IgnoreExceptions &&
769 "LandingPad should not be emitted when -fignore-exceptions are in "
771 EHScope &innermostEHScope = *EHStack.find(EHStack.getInnermostEHScope());
772 switch (innermostEHScope.getKind()) {
773 case EHScope::Terminate:
774 return getTerminateLandingPad();
777 case EHScope::Cleanup:
778 case EHScope::Filter:
779 if (llvm::BasicBlock *lpad = innermostEHScope.getCachedLandingPad())
783 // Save the current IR generation state.
784 CGBuilderTy::InsertPoint savedIP = Builder.saveAndClearIP();
785 auto DL = ApplyDebugLocation::CreateDefaultArtificial(*this, CurEHLocation);
787 // Create and configure the landing pad.
788 llvm::BasicBlock *lpad = createBasicBlock("lpad");
791 llvm::LandingPadInst *LPadInst =
792 Builder.CreateLandingPad(llvm::StructType::get(Int8PtrTy, Int32Ty), 0);
794 llvm::Value *LPadExn = Builder.CreateExtractValue(LPadInst, 0);
795 Builder.CreateStore(LPadExn, getExceptionSlot());
796 llvm::Value *LPadSel = Builder.CreateExtractValue(LPadInst, 1);
797 Builder.CreateStore(LPadSel, getEHSelectorSlot());
799 // Save the exception pointer. It's safe to use a single exception
800 // pointer per function because EH cleanups can never have nested
802 // Build the landingpad instruction.
804 // Accumulate all the handlers in scope.
805 bool hasCatchAll = false;
806 bool hasCleanup = false;
807 bool hasFilter = false;
808 SmallVector<llvm::Value*, 4> filterTypes;
809 llvm::SmallPtrSet<llvm::Value*, 4> catchTypes;
810 for (EHScopeStack::iterator I = EHStack.begin(), E = EHStack.end(); I != E;
813 switch (I->getKind()) {
814 case EHScope::Cleanup:
815 // If we have a cleanup, remember that.
816 hasCleanup = (hasCleanup || cast<EHCleanupScope>(*I).isEHCleanup());
819 case EHScope::Filter: {
820 assert(I.next() == EHStack.end() && "EH filter is not end of EH stack");
821 assert(!hasCatchAll && "EH filter reached after catch-all");
823 // Filter scopes get added to the landingpad in weird ways.
824 EHFilterScope &filter = cast<EHFilterScope>(*I);
827 // Add all the filter values.
828 for (unsigned i = 0, e = filter.getNumFilters(); i != e; ++i)
829 filterTypes.push_back(filter.getFilter(i));
833 case EHScope::Terminate:
834 // Terminate scopes are basically catch-alls.
835 assert(!hasCatchAll);
843 EHCatchScope &catchScope = cast<EHCatchScope>(*I);
844 for (unsigned hi = 0, he = catchScope.getNumHandlers(); hi != he; ++hi) {
845 EHCatchScope::Handler handler = catchScope.getHandler(hi);
846 assert(handler.Type.Flags == 0 &&
847 "landingpads do not support catch handler flags");
849 // If this is a catch-all, register that and abort.
850 if (!handler.Type.RTTI) {
851 assert(!hasCatchAll);
856 // Check whether we already have a handler for this type.
857 if (catchTypes.insert(handler.Type.RTTI).second)
858 // If not, add it directly to the landingpad.
859 LPadInst->addClause(handler.Type.RTTI);
864 // If we have a catch-all, add null to the landingpad.
865 assert(!(hasCatchAll && hasFilter));
867 LPadInst->addClause(getCatchAllValue(*this));
869 // If we have an EH filter, we need to add those handlers in the
870 // right place in the landingpad, which is to say, at the end.
871 } else if (hasFilter) {
872 // Create a filter expression: a constant array indicating which filter
873 // types there are. The personality routine only lands here if the filter
875 SmallVector<llvm::Constant*, 8> Filters;
876 llvm::ArrayType *AType =
877 llvm::ArrayType::get(!filterTypes.empty() ?
878 filterTypes[0]->getType() : Int8PtrTy,
881 for (unsigned i = 0, e = filterTypes.size(); i != e; ++i)
882 Filters.push_back(cast<llvm::Constant>(filterTypes[i]));
883 llvm::Constant *FilterArray = llvm::ConstantArray::get(AType, Filters);
884 LPadInst->addClause(FilterArray);
886 // Also check whether we need a cleanup.
888 LPadInst->setCleanup(true);
890 // Otherwise, signal that we at least have cleanups.
891 } else if (hasCleanup) {
892 LPadInst->setCleanup(true);
895 assert((LPadInst->getNumClauses() > 0 || LPadInst->isCleanup()) &&
896 "landingpad instruction has no clauses!");
898 // Tell the backend how to generate the landing pad.
899 Builder.CreateBr(getEHDispatchBlock(EHStack.getInnermostEHScope()));
901 // Restore the old IR generation state.
902 Builder.restoreIP(savedIP);
907 static void emitCatchPadBlock(CodeGenFunction &CGF, EHCatchScope &CatchScope) {
908 llvm::BasicBlock *DispatchBlock = CatchScope.getCachedEHDispatchBlock();
909 assert(DispatchBlock);
911 CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveIP();
912 CGF.EmitBlockAfterUses(DispatchBlock);
914 llvm::Value *ParentPad = CGF.CurrentFuncletPad;
916 ParentPad = llvm::ConstantTokenNone::get(CGF.getLLVMContext());
917 llvm::BasicBlock *UnwindBB =
918 CGF.getEHDispatchBlock(CatchScope.getEnclosingEHScope());
920 unsigned NumHandlers = CatchScope.getNumHandlers();
921 llvm::CatchSwitchInst *CatchSwitch =
922 CGF.Builder.CreateCatchSwitch(ParentPad, UnwindBB, NumHandlers);
924 // Test against each of the exception types we claim to catch.
925 for (unsigned I = 0; I < NumHandlers; ++I) {
926 const EHCatchScope::Handler &Handler = CatchScope.getHandler(I);
928 CatchTypeInfo TypeInfo = Handler.Type;
930 TypeInfo.RTTI = llvm::Constant::getNullValue(CGF.VoidPtrTy);
932 CGF.Builder.SetInsertPoint(Handler.Block);
934 if (EHPersonality::get(CGF).isMSVCXXPersonality()) {
935 CGF.Builder.CreateCatchPad(
936 CatchSwitch, {TypeInfo.RTTI, CGF.Builder.getInt32(TypeInfo.Flags),
937 llvm::Constant::getNullValue(CGF.VoidPtrTy)});
939 CGF.Builder.CreateCatchPad(CatchSwitch, {TypeInfo.RTTI});
942 CatchSwitch->addHandler(Handler.Block);
944 CGF.Builder.restoreIP(SavedIP);
947 // Wasm uses Windows-style EH instructions, but it merges all catch clauses into
948 // one big catchpad, within which we use Itanium's landingpad-style selector
949 // comparison instructions.
950 static void emitWasmCatchPadBlock(CodeGenFunction &CGF,
951 EHCatchScope &CatchScope) {
952 llvm::BasicBlock *DispatchBlock = CatchScope.getCachedEHDispatchBlock();
953 assert(DispatchBlock);
955 CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveIP();
956 CGF.EmitBlockAfterUses(DispatchBlock);
958 llvm::Value *ParentPad = CGF.CurrentFuncletPad;
960 ParentPad = llvm::ConstantTokenNone::get(CGF.getLLVMContext());
961 llvm::BasicBlock *UnwindBB =
962 CGF.getEHDispatchBlock(CatchScope.getEnclosingEHScope());
964 unsigned NumHandlers = CatchScope.getNumHandlers();
965 llvm::CatchSwitchInst *CatchSwitch =
966 CGF.Builder.CreateCatchSwitch(ParentPad, UnwindBB, NumHandlers);
968 // We don't use a landingpad instruction, so generate intrinsic calls to
969 // provide exception and selector values.
970 llvm::BasicBlock *WasmCatchStartBlock = CGF.createBasicBlock("catch.start");
971 CatchSwitch->addHandler(WasmCatchStartBlock);
972 CGF.EmitBlockAfterUses(WasmCatchStartBlock);
974 // Create a catchpad instruction.
975 SmallVector<llvm::Value *, 4> CatchTypes;
976 for (unsigned I = 0, E = NumHandlers; I < E; ++I) {
977 const EHCatchScope::Handler &Handler = CatchScope.getHandler(I);
978 CatchTypeInfo TypeInfo = Handler.Type;
980 TypeInfo.RTTI = llvm::Constant::getNullValue(CGF.VoidPtrTy);
981 CatchTypes.push_back(TypeInfo.RTTI);
983 auto *CPI = CGF.Builder.CreateCatchPad(CatchSwitch, CatchTypes);
985 // Create calls to wasm.get.exception and wasm.get.ehselector intrinsics.
986 // Before they are lowered appropriately later, they provide values for the
987 // exception and selector.
988 llvm::Function *GetExnFn =
989 CGF.CGM.getIntrinsic(llvm::Intrinsic::wasm_get_exception);
990 llvm::Function *GetSelectorFn =
991 CGF.CGM.getIntrinsic(llvm::Intrinsic::wasm_get_ehselector);
992 llvm::CallInst *Exn = CGF.Builder.CreateCall(GetExnFn, CPI);
993 CGF.Builder.CreateStore(Exn, CGF.getExceptionSlot());
994 llvm::CallInst *Selector = CGF.Builder.CreateCall(GetSelectorFn, CPI);
996 llvm::Function *TypeIDFn = CGF.CGM.getIntrinsic(llvm::Intrinsic::eh_typeid_for);
998 // If there's only a single catch-all, branch directly to its handler.
999 if (CatchScope.getNumHandlers() == 1 &&
1000 CatchScope.getHandler(0).isCatchAll()) {
1001 CGF.Builder.CreateBr(CatchScope.getHandler(0).Block);
1002 CGF.Builder.restoreIP(SavedIP);
1006 // Test against each of the exception types we claim to catch.
1007 for (unsigned I = 0, E = NumHandlers;; ++I) {
1008 assert(I < E && "ran off end of handlers!");
1009 const EHCatchScope::Handler &Handler = CatchScope.getHandler(I);
1010 CatchTypeInfo TypeInfo = Handler.Type;
1012 TypeInfo.RTTI = llvm::Constant::getNullValue(CGF.VoidPtrTy);
1014 // Figure out the next block.
1015 llvm::BasicBlock *NextBlock;
1017 bool EmitNextBlock = false, NextIsEnd = false;
1019 // If this is the last handler, we're at the end, and the next block is a
1020 // block that contains a call to the rethrow function, so we can unwind to
1021 // the enclosing EH scope. The call itself will be generated later.
1023 NextBlock = CGF.createBasicBlock("rethrow");
1024 EmitNextBlock = true;
1027 // If the next handler is a catch-all, we're at the end, and the
1028 // next block is that handler.
1029 } else if (CatchScope.getHandler(I + 1).isCatchAll()) {
1030 NextBlock = CatchScope.getHandler(I + 1).Block;
1033 // Otherwise, we're not at the end and we need a new block.
1035 NextBlock = CGF.createBasicBlock("catch.fallthrough");
1036 EmitNextBlock = true;
1039 // Figure out the catch type's index in the LSDA's type table.
1040 llvm::CallInst *TypeIndex = CGF.Builder.CreateCall(TypeIDFn, TypeInfo.RTTI);
1041 TypeIndex->setDoesNotThrow();
1043 llvm::Value *MatchesTypeIndex =
1044 CGF.Builder.CreateICmpEQ(Selector, TypeIndex, "matches");
1045 CGF.Builder.CreateCondBr(MatchesTypeIndex, Handler.Block, NextBlock);
1048 CGF.EmitBlock(NextBlock);
1053 CGF.Builder.restoreIP(SavedIP);
1056 /// Emit the structure of the dispatch block for the given catch scope.
1057 /// It is an invariant that the dispatch block already exists.
1058 static void emitCatchDispatchBlock(CodeGenFunction &CGF,
1059 EHCatchScope &catchScope) {
1060 if (EHPersonality::get(CGF).isWasmPersonality())
1061 return emitWasmCatchPadBlock(CGF, catchScope);
1062 if (EHPersonality::get(CGF).usesFuncletPads())
1063 return emitCatchPadBlock(CGF, catchScope);
1065 llvm::BasicBlock *dispatchBlock = catchScope.getCachedEHDispatchBlock();
1066 assert(dispatchBlock);
1068 // If there's only a single catch-all, getEHDispatchBlock returned
1069 // that catch-all as the dispatch block.
1070 if (catchScope.getNumHandlers() == 1 &&
1071 catchScope.getHandler(0).isCatchAll()) {
1072 assert(dispatchBlock == catchScope.getHandler(0).Block);
1076 CGBuilderTy::InsertPoint savedIP = CGF.Builder.saveIP();
1077 CGF.EmitBlockAfterUses(dispatchBlock);
1079 // Select the right handler.
1080 llvm::Function *llvm_eh_typeid_for =
1081 CGF.CGM.getIntrinsic(llvm::Intrinsic::eh_typeid_for);
1083 // Load the selector value.
1084 llvm::Value *selector = CGF.getSelectorFromSlot();
1086 // Test against each of the exception types we claim to catch.
1087 for (unsigned i = 0, e = catchScope.getNumHandlers(); ; ++i) {
1088 assert(i < e && "ran off end of handlers!");
1089 const EHCatchScope::Handler &handler = catchScope.getHandler(i);
1091 llvm::Value *typeValue = handler.Type.RTTI;
1092 assert(handler.Type.Flags == 0 &&
1093 "landingpads do not support catch handler flags");
1094 assert(typeValue && "fell into catch-all case!");
1095 typeValue = CGF.Builder.CreateBitCast(typeValue, CGF.Int8PtrTy);
1097 // Figure out the next block.
1099 llvm::BasicBlock *nextBlock;
1101 // If this is the last handler, we're at the end, and the next
1102 // block is the block for the enclosing EH scope.
1104 nextBlock = CGF.getEHDispatchBlock(catchScope.getEnclosingEHScope());
1107 // If the next handler is a catch-all, we're at the end, and the
1108 // next block is that handler.
1109 } else if (catchScope.getHandler(i+1).isCatchAll()) {
1110 nextBlock = catchScope.getHandler(i+1).Block;
1113 // Otherwise, we're not at the end and we need a new block.
1115 nextBlock = CGF.createBasicBlock("catch.fallthrough");
1119 // Figure out the catch type's index in the LSDA's type table.
1120 llvm::CallInst *typeIndex =
1121 CGF.Builder.CreateCall(llvm_eh_typeid_for, typeValue);
1122 typeIndex->setDoesNotThrow();
1124 llvm::Value *matchesTypeIndex =
1125 CGF.Builder.CreateICmpEQ(selector, typeIndex, "matches");
1126 CGF.Builder.CreateCondBr(matchesTypeIndex, handler.Block, nextBlock);
1128 // If the next handler is a catch-all, we're completely done.
1130 CGF.Builder.restoreIP(savedIP);
1133 // Otherwise we need to emit and continue at that block.
1134 CGF.EmitBlock(nextBlock);
1138 void CodeGenFunction::popCatchScope() {
1139 EHCatchScope &catchScope = cast<EHCatchScope>(*EHStack.begin());
1140 if (catchScope.hasEHBranches())
1141 emitCatchDispatchBlock(*this, catchScope);
1145 void CodeGenFunction::ExitCXXTryStmt(const CXXTryStmt &S, bool IsFnTryBlock) {
1146 unsigned NumHandlers = S.getNumHandlers();
1147 EHCatchScope &CatchScope = cast<EHCatchScope>(*EHStack.begin());
1148 assert(CatchScope.getNumHandlers() == NumHandlers);
1149 llvm::BasicBlock *DispatchBlock = CatchScope.getCachedEHDispatchBlock();
1151 // If the catch was not required, bail out now.
1152 if (!CatchScope.hasEHBranches()) {
1153 CatchScope.clearHandlerBlocks();
1158 // Emit the structure of the EH dispatch for this catch.
1159 emitCatchDispatchBlock(*this, CatchScope);
1161 // Copy the handler blocks off before we pop the EH stack. Emitting
1162 // the handlers might scribble on this memory.
1163 SmallVector<EHCatchScope::Handler, 8> Handlers(
1164 CatchScope.begin(), CatchScope.begin() + NumHandlers);
1168 // The fall-through block.
1169 llvm::BasicBlock *ContBB = createBasicBlock("try.cont");
1171 // We just emitted the body of the try; jump to the continue block.
1172 if (HaveInsertPoint())
1173 Builder.CreateBr(ContBB);
1175 // Determine if we need an implicit rethrow for all these catch handlers;
1176 // see the comment below.
1177 bool doImplicitRethrow = false;
1179 doImplicitRethrow = isa<CXXDestructorDecl>(CurCodeDecl) ||
1180 isa<CXXConstructorDecl>(CurCodeDecl);
1182 // Wasm uses Windows-style EH instructions, but merges all catch clauses into
1183 // one big catchpad. So we save the old funclet pad here before we traverse
1184 // each catch handler.
1185 SaveAndRestore<llvm::Instruction *> RestoreCurrentFuncletPad(
1187 llvm::BasicBlock *WasmCatchStartBlock = nullptr;
1188 if (EHPersonality::get(*this).isWasmPersonality()) {
1190 cast<llvm::CatchSwitchInst>(DispatchBlock->getFirstNonPHI());
1191 WasmCatchStartBlock = CatchSwitch->hasUnwindDest()
1192 ? CatchSwitch->getSuccessor(1)
1193 : CatchSwitch->getSuccessor(0);
1194 auto *CPI = cast<llvm::CatchPadInst>(WasmCatchStartBlock->getFirstNonPHI());
1195 CurrentFuncletPad = CPI;
1198 // Perversely, we emit the handlers backwards precisely because we
1199 // want them to appear in source order. In all of these cases, the
1200 // catch block will have exactly one predecessor, which will be a
1201 // particular block in the catch dispatch. However, in the case of
1202 // a catch-all, one of the dispatch blocks will branch to two
1203 // different handlers, and EmitBlockAfterUses will cause the second
1204 // handler to be moved before the first.
1205 bool HasCatchAll = false;
1206 for (unsigned I = NumHandlers; I != 0; --I) {
1207 HasCatchAll |= Handlers[I - 1].isCatchAll();
1208 llvm::BasicBlock *CatchBlock = Handlers[I-1].Block;
1209 EmitBlockAfterUses(CatchBlock);
1211 // Catch the exception if this isn't a catch-all.
1212 const CXXCatchStmt *C = S.getHandler(I-1);
1214 // Enter a cleanup scope, including the catch variable and the
1216 RunCleanupsScope CatchScope(*this);
1218 // Initialize the catch variable and set up the cleanups.
1219 SaveAndRestore<llvm::Instruction *> RestoreCurrentFuncletPad(
1221 CGM.getCXXABI().emitBeginCatch(*this, C);
1223 // Emit the PGO counter increment.
1224 incrementProfileCounter(C);
1226 // Perform the body of the catch.
1227 EmitStmt(C->getHandlerBlock());
1229 // [except.handle]p11:
1230 // The currently handled exception is rethrown if control
1231 // reaches the end of a handler of the function-try-block of a
1232 // constructor or destructor.
1234 // It is important that we only do this on fallthrough and not on
1235 // return. Note that it's illegal to put a return in a
1236 // constructor function-try-block's catch handler (p14), so this
1237 // really only applies to destructors.
1238 if (doImplicitRethrow && HaveInsertPoint()) {
1239 CGM.getCXXABI().emitRethrow(*this, /*isNoReturn*/false);
1240 Builder.CreateUnreachable();
1241 Builder.ClearInsertionPoint();
1244 // Fall out through the catch cleanups.
1245 CatchScope.ForceCleanup();
1247 // Branch out of the try.
1248 if (HaveInsertPoint())
1249 Builder.CreateBr(ContBB);
1252 // Because in wasm we merge all catch clauses into one big catchpad, in case
1253 // none of the types in catch handlers matches after we test against each of
1254 // them, we should unwind to the next EH enclosing scope. We generate a call
1255 // to rethrow function here to do that.
1256 if (EHPersonality::get(*this).isWasmPersonality() && !HasCatchAll) {
1257 assert(WasmCatchStartBlock);
1258 // Navigate for the "rethrow" block we created in emitWasmCatchPadBlock().
1259 // Wasm uses landingpad-style conditional branches to compare selectors, so
1260 // we follow the false destination for each of the cond branches to reach
1261 // the rethrow block.
1262 llvm::BasicBlock *RethrowBlock = WasmCatchStartBlock;
1263 while (llvm::Instruction *TI = RethrowBlock->getTerminator()) {
1264 auto *BI = cast<llvm::BranchInst>(TI);
1265 assert(BI->isConditional());
1266 RethrowBlock = BI->getSuccessor(1);
1268 assert(RethrowBlock != WasmCatchStartBlock && RethrowBlock->empty());
1269 Builder.SetInsertPoint(RethrowBlock);
1270 llvm::Function *RethrowInCatchFn =
1271 CGM.getIntrinsic(llvm::Intrinsic::wasm_rethrow_in_catch);
1272 EmitNoreturnRuntimeCallOrInvoke(RethrowInCatchFn, {});
1276 incrementProfileCounter(&S);
1280 struct CallEndCatchForFinally final : EHScopeStack::Cleanup {
1281 llvm::Value *ForEHVar;
1282 llvm::FunctionCallee EndCatchFn;
1283 CallEndCatchForFinally(llvm::Value *ForEHVar,
1284 llvm::FunctionCallee EndCatchFn)
1285 : ForEHVar(ForEHVar), EndCatchFn(EndCatchFn) {}
1287 void Emit(CodeGenFunction &CGF, Flags flags) override {
1288 llvm::BasicBlock *EndCatchBB = CGF.createBasicBlock("finally.endcatch");
1289 llvm::BasicBlock *CleanupContBB =
1290 CGF.createBasicBlock("finally.cleanup.cont");
1292 llvm::Value *ShouldEndCatch =
1293 CGF.Builder.CreateFlagLoad(ForEHVar, "finally.endcatch");
1294 CGF.Builder.CreateCondBr(ShouldEndCatch, EndCatchBB, CleanupContBB);
1295 CGF.EmitBlock(EndCatchBB);
1296 CGF.EmitRuntimeCallOrInvoke(EndCatchFn); // catch-all, so might throw
1297 CGF.EmitBlock(CleanupContBB);
1301 struct PerformFinally final : EHScopeStack::Cleanup {
1303 llvm::Value *ForEHVar;
1304 llvm::FunctionCallee EndCatchFn;
1305 llvm::FunctionCallee RethrowFn;
1306 llvm::Value *SavedExnVar;
1308 PerformFinally(const Stmt *Body, llvm::Value *ForEHVar,
1309 llvm::FunctionCallee EndCatchFn,
1310 llvm::FunctionCallee RethrowFn, llvm::Value *SavedExnVar)
1311 : Body(Body), ForEHVar(ForEHVar), EndCatchFn(EndCatchFn),
1312 RethrowFn(RethrowFn), SavedExnVar(SavedExnVar) {}
1314 void Emit(CodeGenFunction &CGF, Flags flags) override {
1315 // Enter a cleanup to call the end-catch function if one was provided.
1317 CGF.EHStack.pushCleanup<CallEndCatchForFinally>(NormalAndEHCleanup,
1318 ForEHVar, EndCatchFn);
1320 // Save the current cleanup destination in case there are
1321 // cleanups in the finally block.
1322 llvm::Value *SavedCleanupDest =
1323 CGF.Builder.CreateLoad(CGF.getNormalCleanupDestSlot(),
1324 "cleanup.dest.saved");
1326 // Emit the finally block.
1329 // If the end of the finally is reachable, check whether this was
1330 // for EH. If so, rethrow.
1331 if (CGF.HaveInsertPoint()) {
1332 llvm::BasicBlock *RethrowBB = CGF.createBasicBlock("finally.rethrow");
1333 llvm::BasicBlock *ContBB = CGF.createBasicBlock("finally.cont");
1335 llvm::Value *ShouldRethrow =
1336 CGF.Builder.CreateFlagLoad(ForEHVar, "finally.shouldthrow");
1337 CGF.Builder.CreateCondBr(ShouldRethrow, RethrowBB, ContBB);
1339 CGF.EmitBlock(RethrowBB);
1341 CGF.EmitRuntimeCallOrInvoke(RethrowFn,
1342 CGF.Builder.CreateAlignedLoad(SavedExnVar, CGF.getPointerAlign()));
1344 CGF.EmitRuntimeCallOrInvoke(RethrowFn);
1346 CGF.Builder.CreateUnreachable();
1348 CGF.EmitBlock(ContBB);
1350 // Restore the cleanup destination.
1351 CGF.Builder.CreateStore(SavedCleanupDest,
1352 CGF.getNormalCleanupDestSlot());
1355 // Leave the end-catch cleanup. As an optimization, pretend that
1356 // the fallthrough path was inaccessible; we've dynamically proven
1357 // that we're not in the EH case along that path.
1359 CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveAndClearIP();
1360 CGF.PopCleanupBlock();
1361 CGF.Builder.restoreIP(SavedIP);
1364 // Now make sure we actually have an insertion point or the
1365 // cleanup gods will hate us.
1366 CGF.EnsureInsertPoint();
1369 } // end anonymous namespace
1371 /// Enters a finally block for an implementation using zero-cost
1372 /// exceptions. This is mostly general, but hard-codes some
1373 /// language/ABI-specific behavior in the catch-all sections.
1374 void CodeGenFunction::FinallyInfo::enter(CodeGenFunction &CGF, const Stmt *body,
1375 llvm::FunctionCallee beginCatchFn,
1376 llvm::FunctionCallee endCatchFn,
1377 llvm::FunctionCallee rethrowFn) {
1378 assert((!!beginCatchFn) == (!!endCatchFn) &&
1379 "begin/end catch functions not paired");
1380 assert(rethrowFn && "rethrow function is required");
1382 BeginCatchFn = beginCatchFn;
1384 // The rethrow function has one of the following two types:
1387 // In the latter case we need to pass it the exception object.
1388 // But we can't use the exception slot because the @finally might
1389 // have a landing pad (which would overwrite the exception slot).
1390 llvm::FunctionType *rethrowFnTy = rethrowFn.getFunctionType();
1391 SavedExnVar = nullptr;
1392 if (rethrowFnTy->getNumParams())
1393 SavedExnVar = CGF.CreateTempAlloca(CGF.Int8PtrTy, "finally.exn");
1395 // A finally block is a statement which must be executed on any edge
1396 // out of a given scope. Unlike a cleanup, the finally block may
1397 // contain arbitrary control flow leading out of itself. In
1398 // addition, finally blocks should always be executed, even if there
1399 // are no catch handlers higher on the stack. Therefore, we
1400 // surround the protected scope with a combination of a normal
1401 // cleanup (to catch attempts to break out of the block via normal
1402 // control flow) and an EH catch-all (semantically "outside" any try
1403 // statement to which the finally block might have been attached).
1404 // The finally block itself is generated in the context of a cleanup
1405 // which conditionally leaves the catch-all.
1407 // Jump destination for performing the finally block on an exception
1408 // edge. We'll never actually reach this block, so unreachable is
1410 RethrowDest = CGF.getJumpDestInCurrentScope(CGF.getUnreachableBlock());
1412 // Whether the finally block is being executed for EH purposes.
1413 ForEHVar = CGF.CreateTempAlloca(CGF.Builder.getInt1Ty(), "finally.for-eh");
1414 CGF.Builder.CreateFlagStore(false, ForEHVar);
1416 // Enter a normal cleanup which will perform the @finally block.
1417 CGF.EHStack.pushCleanup<PerformFinally>(NormalCleanup, body,
1418 ForEHVar, endCatchFn,
1419 rethrowFn, SavedExnVar);
1421 // Enter a catch-all scope.
1422 llvm::BasicBlock *catchBB = CGF.createBasicBlock("finally.catchall");
1423 EHCatchScope *catchScope = CGF.EHStack.pushCatch(1);
1424 catchScope->setCatchAllHandler(0, catchBB);
1427 void CodeGenFunction::FinallyInfo::exit(CodeGenFunction &CGF) {
1428 // Leave the finally catch-all.
1429 EHCatchScope &catchScope = cast<EHCatchScope>(*CGF.EHStack.begin());
1430 llvm::BasicBlock *catchBB = catchScope.getHandler(0).Block;
1432 CGF.popCatchScope();
1434 // If there are any references to the catch-all block, emit it.
1435 if (catchBB->use_empty()) {
1438 CGBuilderTy::InsertPoint savedIP = CGF.Builder.saveAndClearIP();
1439 CGF.EmitBlock(catchBB);
1441 llvm::Value *exn = nullptr;
1443 // If there's a begin-catch function, call it.
1445 exn = CGF.getExceptionFromSlot();
1446 CGF.EmitNounwindRuntimeCall(BeginCatchFn, exn);
1449 // If we need to remember the exception pointer to rethrow later, do so.
1451 if (!exn) exn = CGF.getExceptionFromSlot();
1452 CGF.Builder.CreateAlignedStore(exn, SavedExnVar, CGF.getPointerAlign());
1455 // Tell the cleanups in the finally block that we're do this for EH.
1456 CGF.Builder.CreateFlagStore(true, ForEHVar);
1458 // Thread a jump through the finally cleanup.
1459 CGF.EmitBranchThroughCleanup(RethrowDest);
1461 CGF.Builder.restoreIP(savedIP);
1464 // Finally, leave the @finally cleanup.
1465 CGF.PopCleanupBlock();
1468 llvm::BasicBlock *CodeGenFunction::getTerminateLandingPad() {
1469 if (TerminateLandingPad)
1470 return TerminateLandingPad;
1472 CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
1474 // This will get inserted at the end of the function.
1475 TerminateLandingPad = createBasicBlock("terminate.lpad");
1476 Builder.SetInsertPoint(TerminateLandingPad);
1478 // Tell the backend that this is a landing pad.
1479 const EHPersonality &Personality = EHPersonality::get(*this);
1481 if (!CurFn->hasPersonalityFn())
1482 CurFn->setPersonalityFn(getOpaquePersonalityFn(CGM, Personality));
1484 llvm::LandingPadInst *LPadInst =
1485 Builder.CreateLandingPad(llvm::StructType::get(Int8PtrTy, Int32Ty), 0);
1486 LPadInst->addClause(getCatchAllValue(*this));
1488 llvm::Value *Exn = nullptr;
1489 if (getLangOpts().CPlusPlus)
1490 Exn = Builder.CreateExtractValue(LPadInst, 0);
1491 llvm::CallInst *terminateCall =
1492 CGM.getCXXABI().emitTerminateForUnexpectedException(*this, Exn);
1493 terminateCall->setDoesNotReturn();
1494 Builder.CreateUnreachable();
1496 // Restore the saved insertion state.
1497 Builder.restoreIP(SavedIP);
1499 return TerminateLandingPad;
1502 llvm::BasicBlock *CodeGenFunction::getTerminateHandler() {
1503 if (TerminateHandler)
1504 return TerminateHandler;
1506 // Set up the terminate handler. This block is inserted at the very
1507 // end of the function by FinishFunction.
1508 TerminateHandler = createBasicBlock("terminate.handler");
1509 CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
1510 Builder.SetInsertPoint(TerminateHandler);
1512 llvm::Value *Exn = nullptr;
1513 if (getLangOpts().CPlusPlus)
1514 Exn = getExceptionFromSlot();
1515 llvm::CallInst *terminateCall =
1516 CGM.getCXXABI().emitTerminateForUnexpectedException(*this, Exn);
1517 terminateCall->setDoesNotReturn();
1518 Builder.CreateUnreachable();
1520 // Restore the saved insertion state.
1521 Builder.restoreIP(SavedIP);
1523 return TerminateHandler;
1526 llvm::BasicBlock *CodeGenFunction::getTerminateFunclet() {
1527 assert(EHPersonality::get(*this).usesFuncletPads() &&
1528 "use getTerminateLandingPad for non-funclet EH");
1530 llvm::BasicBlock *&TerminateFunclet = TerminateFunclets[CurrentFuncletPad];
1531 if (TerminateFunclet)
1532 return TerminateFunclet;
1534 CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
1536 // Set up the terminate handler. This block is inserted at the very
1537 // end of the function by FinishFunction.
1538 TerminateFunclet = createBasicBlock("terminate.handler");
1539 Builder.SetInsertPoint(TerminateFunclet);
1541 // Create the cleanuppad using the current parent pad as its token. Use 'none'
1542 // if this is a top-level terminate scope, which is the common case.
1543 SaveAndRestore<llvm::Instruction *> RestoreCurrentFuncletPad(
1545 llvm::Value *ParentPad = CurrentFuncletPad;
1547 ParentPad = llvm::ConstantTokenNone::get(CGM.getLLVMContext());
1548 CurrentFuncletPad = Builder.CreateCleanupPad(ParentPad);
1550 // Emit the __std_terminate call.
1551 llvm::Value *Exn = nullptr;
1552 // In case of wasm personality, we need to pass the exception value to
1553 // __clang_call_terminate function.
1554 if (getLangOpts().CPlusPlus &&
1555 EHPersonality::get(*this).isWasmPersonality()) {
1556 llvm::Function *GetExnFn =
1557 CGM.getIntrinsic(llvm::Intrinsic::wasm_get_exception);
1558 Exn = Builder.CreateCall(GetExnFn, CurrentFuncletPad);
1560 llvm::CallInst *terminateCall =
1561 CGM.getCXXABI().emitTerminateForUnexpectedException(*this, Exn);
1562 terminateCall->setDoesNotReturn();
1563 Builder.CreateUnreachable();
1565 // Restore the saved insertion state.
1566 Builder.restoreIP(SavedIP);
1568 return TerminateFunclet;
1571 llvm::BasicBlock *CodeGenFunction::getEHResumeBlock(bool isCleanup) {
1572 if (EHResumeBlock) return EHResumeBlock;
1574 CGBuilderTy::InsertPoint SavedIP = Builder.saveIP();
1576 // We emit a jump to a notional label at the outermost unwind state.
1577 EHResumeBlock = createBasicBlock("eh.resume");
1578 Builder.SetInsertPoint(EHResumeBlock);
1580 const EHPersonality &Personality = EHPersonality::get(*this);
1582 // This can always be a call because we necessarily didn't find
1583 // anything on the EH stack which needs our help.
1584 const char *RethrowName = Personality.CatchallRethrowFn;
1585 if (RethrowName != nullptr && !isCleanup) {
1586 EmitRuntimeCall(getCatchallRethrowFn(CGM, RethrowName),
1587 getExceptionFromSlot())->setDoesNotReturn();
1588 Builder.CreateUnreachable();
1589 Builder.restoreIP(SavedIP);
1590 return EHResumeBlock;
1593 // Recreate the landingpad's return value for the 'resume' instruction.
1594 llvm::Value *Exn = getExceptionFromSlot();
1595 llvm::Value *Sel = getSelectorFromSlot();
1597 llvm::Type *LPadType = llvm::StructType::get(Exn->getType(), Sel->getType());
1598 llvm::Value *LPadVal = llvm::UndefValue::get(LPadType);
1599 LPadVal = Builder.CreateInsertValue(LPadVal, Exn, 0, "lpad.val");
1600 LPadVal = Builder.CreateInsertValue(LPadVal, Sel, 1, "lpad.val");
1602 Builder.CreateResume(LPadVal);
1603 Builder.restoreIP(SavedIP);
1604 return EHResumeBlock;
1607 void CodeGenFunction::EmitSEHTryStmt(const SEHTryStmt &S) {
1610 JumpDest TryExit = getJumpDestInCurrentScope("__try.__leave");
1612 SEHTryEpilogueStack.push_back(&TryExit);
1613 EmitStmt(S.getTryBlock());
1614 SEHTryEpilogueStack.pop_back();
1616 if (!TryExit.getBlock()->use_empty())
1617 EmitBlock(TryExit.getBlock(), /*IsFinished=*/true);
1619 delete TryExit.getBlock();
1625 struct PerformSEHFinally final : EHScopeStack::Cleanup {
1626 llvm::Function *OutlinedFinally;
1627 PerformSEHFinally(llvm::Function *OutlinedFinally)
1628 : OutlinedFinally(OutlinedFinally) {}
1630 void Emit(CodeGenFunction &CGF, Flags F) override {
1631 ASTContext &Context = CGF.getContext();
1632 CodeGenModule &CGM = CGF.CGM;
1636 // Compute the two argument values.
1637 QualType ArgTys[2] = {Context.UnsignedCharTy, Context.VoidPtrTy};
1638 llvm::Value *FP = nullptr;
1639 // If CFG.IsOutlinedSEHHelper is true, then we are within a finally block.
1640 if (CGF.IsOutlinedSEHHelper) {
1641 FP = &CGF.CurFn->arg_begin()[1];
1643 llvm::Function *LocalAddrFn =
1644 CGM.getIntrinsic(llvm::Intrinsic::localaddress);
1645 FP = CGF.Builder.CreateCall(LocalAddrFn);
1648 llvm::Value *IsForEH =
1649 llvm::ConstantInt::get(CGF.ConvertType(ArgTys[0]), F.isForEHCleanup());
1651 // Except _leave and fall-through at the end, all other exits in a _try
1652 // (return/goto/continue/break) are considered as abnormal terminations
1653 // since _leave/fall-through is always Indexed 0,
1654 // just use NormalCleanupDestSlot (>= 1 for goto/return/..),
1655 // as 1st Arg to indicate abnormal termination
1656 if (!F.isForEHCleanup() && F.hasExitSwitch()) {
1657 Address Addr = CGF.getNormalCleanupDestSlot();
1658 llvm::Value *Load = CGF.Builder.CreateLoad(Addr, "cleanup.dest");
1659 llvm::Value *Zero = llvm::Constant::getNullValue(CGM.Int32Ty);
1660 IsForEH = CGF.Builder.CreateICmpNE(Load, Zero);
1663 Args.add(RValue::get(IsForEH), ArgTys[0]);
1664 Args.add(RValue::get(FP), ArgTys[1]);
1666 // Arrange a two-arg function info and type.
1667 const CGFunctionInfo &FnInfo =
1668 CGM.getTypes().arrangeBuiltinFunctionCall(Context.VoidTy, Args);
1670 auto Callee = CGCallee::forDirect(OutlinedFinally);
1671 CGF.EmitCall(FnInfo, Callee, ReturnValueSlot(), Args);
1674 } // end anonymous namespace
1677 /// Find all local variable captures in the statement.
1678 struct CaptureFinder : ConstStmtVisitor<CaptureFinder> {
1679 CodeGenFunction &ParentCGF;
1680 const VarDecl *ParentThis;
1681 llvm::SmallSetVector<const VarDecl *, 4> Captures;
1682 Address SEHCodeSlot = Address::invalid();
1683 CaptureFinder(CodeGenFunction &ParentCGF, const VarDecl *ParentThis)
1684 : ParentCGF(ParentCGF), ParentThis(ParentThis) {}
1686 // Return true if we need to do any capturing work.
1687 bool foundCaptures() {
1688 return !Captures.empty() || SEHCodeSlot.isValid();
1691 void Visit(const Stmt *S) {
1692 // See if this is a capture, then recurse.
1693 ConstStmtVisitor<CaptureFinder>::Visit(S);
1694 for (const Stmt *Child : S->children())
1699 void VisitDeclRefExpr(const DeclRefExpr *E) {
1700 // If this is already a capture, just make sure we capture 'this'.
1701 if (E->refersToEnclosingVariableOrCapture()) {
1702 Captures.insert(ParentThis);
1706 const auto *D = dyn_cast<VarDecl>(E->getDecl());
1707 if (D && D->isLocalVarDeclOrParm() && D->hasLocalStorage())
1711 void VisitCXXThisExpr(const CXXThisExpr *E) {
1712 Captures.insert(ParentThis);
1715 void VisitCallExpr(const CallExpr *E) {
1716 // We only need to add parent frame allocations for these builtins in x86.
1717 if (ParentCGF.getTarget().getTriple().getArch() != llvm::Triple::x86)
1720 unsigned ID = E->getBuiltinCallee();
1722 case Builtin::BI__exception_code:
1723 case Builtin::BI_exception_code:
1724 // This is the simple case where we are the outermost finally. All we
1725 // have to do here is make sure we escape this and recover it in the
1726 // outlined handler.
1727 if (!SEHCodeSlot.isValid())
1728 SEHCodeSlot = ParentCGF.SEHCodeSlotStack.back();
1733 } // end anonymous namespace
1735 Address CodeGenFunction::recoverAddrOfEscapedLocal(CodeGenFunction &ParentCGF,
1737 llvm::Value *ParentFP) {
1738 llvm::CallInst *RecoverCall = nullptr;
1739 CGBuilderTy Builder(*this, AllocaInsertPt);
1740 if (auto *ParentAlloca = dyn_cast<llvm::AllocaInst>(ParentVar.getPointer())) {
1741 // Mark the variable escaped if nobody else referenced it and compute the
1742 // localescape index.
1743 auto InsertPair = ParentCGF.EscapedLocals.insert(
1744 std::make_pair(ParentAlloca, ParentCGF.EscapedLocals.size()));
1745 int FrameEscapeIdx = InsertPair.first->second;
1746 // call i8* @llvm.localrecover(i8* bitcast(@parentFn), i8* %fp, i32 N)
1747 llvm::Function *FrameRecoverFn = llvm::Intrinsic::getDeclaration(
1748 &CGM.getModule(), llvm::Intrinsic::localrecover);
1749 llvm::Constant *ParentI8Fn =
1750 llvm::ConstantExpr::getBitCast(ParentCGF.CurFn, Int8PtrTy);
1751 RecoverCall = Builder.CreateCall(
1752 FrameRecoverFn, {ParentI8Fn, ParentFP,
1753 llvm::ConstantInt::get(Int32Ty, FrameEscapeIdx)});
1756 // If the parent didn't have an alloca, we're doing some nested outlining.
1757 // Just clone the existing localrecover call, but tweak the FP argument to
1758 // use our FP value. All other arguments are constants.
1759 auto *ParentRecover =
1760 cast<llvm::IntrinsicInst>(ParentVar.getPointer()->stripPointerCasts());
1761 assert(ParentRecover->getIntrinsicID() == llvm::Intrinsic::localrecover &&
1762 "expected alloca or localrecover in parent LocalDeclMap");
1763 RecoverCall = cast<llvm::CallInst>(ParentRecover->clone());
1764 RecoverCall->setArgOperand(1, ParentFP);
1765 RecoverCall->insertBefore(AllocaInsertPt);
1768 // Bitcast the variable, rename it, and insert it in the local decl map.
1769 llvm::Value *ChildVar =
1770 Builder.CreateBitCast(RecoverCall, ParentVar.getType());
1771 ChildVar->setName(ParentVar.getName());
1772 return Address(ChildVar, ParentVar.getAlignment());
1775 void CodeGenFunction::EmitCapturedLocals(CodeGenFunction &ParentCGF,
1776 const Stmt *OutlinedStmt,
1778 // Find all captures in the Stmt.
1779 CaptureFinder Finder(ParentCGF, ParentCGF.CXXABIThisDecl);
1780 Finder.Visit(OutlinedStmt);
1782 // We can exit early on x86_64 when there are no captures. We just have to
1783 // save the exception code in filters so that __exception_code() works.
1784 if (!Finder.foundCaptures() &&
1785 CGM.getTarget().getTriple().getArch() != llvm::Triple::x86) {
1787 EmitSEHExceptionCodeSave(ParentCGF, nullptr, nullptr);
1791 llvm::Value *EntryFP = nullptr;
1792 CGBuilderTy Builder(CGM, AllocaInsertPt);
1793 if (IsFilter && CGM.getTarget().getTriple().getArch() == llvm::Triple::x86) {
1794 // 32-bit SEH filters need to be careful about FP recovery. The end of the
1795 // EH registration is passed in as the EBP physical register. We can
1796 // recover that with llvm.frameaddress(1).
1797 EntryFP = Builder.CreateCall(
1798 CGM.getIntrinsic(llvm::Intrinsic::frameaddress, AllocaInt8PtrTy),
1799 {Builder.getInt32(1)});
1801 // Otherwise, for x64 and 32-bit finally functions, the parent FP is the
1802 // second parameter.
1803 auto AI = CurFn->arg_begin();
1808 llvm::Value *ParentFP = EntryFP;
1810 // Given whatever FP the runtime provided us in EntryFP, recover the true
1811 // frame pointer of the parent function. We only need to do this in filters,
1812 // since finally funclets recover the parent FP for us.
1813 llvm::Function *RecoverFPIntrin =
1814 CGM.getIntrinsic(llvm::Intrinsic::eh_recoverfp);
1815 llvm::Constant *ParentI8Fn =
1816 llvm::ConstantExpr::getBitCast(ParentCGF.CurFn, Int8PtrTy);
1817 ParentFP = Builder.CreateCall(RecoverFPIntrin, {ParentI8Fn, EntryFP});
1819 // if the parent is a _finally, the passed-in ParentFP is the FP
1820 // of parent _finally, not Establisher's FP (FP of outermost function).
1821 // Establkisher FP is 2nd paramenter passed into parent _finally.
1822 // Fortunately, it's always saved in parent's frame. The following
1823 // code retrieves it, and escapes it so that spill instruction won't be
1825 if (ParentCGF.ParentCGF != nullptr) {
1826 // Locate and escape Parent's frame_pointer.addr alloca
1827 // Depending on target, should be 1st/2nd one in LocalDeclMap.
1828 // Let's just scan for ImplicitParamDecl with VoidPtrTy.
1829 llvm::AllocaInst *FramePtrAddrAlloca = nullptr;
1830 for (auto &I : ParentCGF.LocalDeclMap) {
1831 const VarDecl *D = cast<VarDecl>(I.first);
1832 if (isa<ImplicitParamDecl>(D) &&
1833 D->getType() == getContext().VoidPtrTy) {
1834 assert(D->getName().startswith("frame_pointer"));
1835 FramePtrAddrAlloca = cast<llvm::AllocaInst>(I.second.getPointer());
1839 assert(FramePtrAddrAlloca);
1840 auto InsertPair = ParentCGF.EscapedLocals.insert(
1841 std::make_pair(FramePtrAddrAlloca, ParentCGF.EscapedLocals.size()));
1842 int FrameEscapeIdx = InsertPair.first->second;
1844 // an example of a filter's prolog::
1845 // %0 = call i8* @llvm.eh.recoverfp(bitcast(@"?fin$0@0@main@@"),..)
1846 // %1 = call i8* @llvm.localrecover(bitcast(@"?fin$0@0@main@@"),..)
1847 // %2 = bitcast i8* %1 to i8**
1848 // %3 = load i8*, i8* *%2, align 8
1849 // ==> %3 is the frame-pointer of outermost host function
1850 llvm::Function *FrameRecoverFn = llvm::Intrinsic::getDeclaration(
1851 &CGM.getModule(), llvm::Intrinsic::localrecover);
1852 llvm::Constant *ParentI8Fn =
1853 llvm::ConstantExpr::getBitCast(ParentCGF.CurFn, Int8PtrTy);
1854 ParentFP = Builder.CreateCall(
1855 FrameRecoverFn, {ParentI8Fn, ParentFP,
1856 llvm::ConstantInt::get(Int32Ty, FrameEscapeIdx)});
1857 ParentFP = Builder.CreateBitCast(ParentFP, CGM.VoidPtrPtrTy);
1858 ParentFP = Builder.CreateLoad(Address(ParentFP, getPointerAlign()));
1862 // Create llvm.localrecover calls for all captures.
1863 for (const VarDecl *VD : Finder.Captures) {
1864 if (isa<ImplicitParamDecl>(VD)) {
1865 CGM.ErrorUnsupported(VD, "'this' captured by SEH");
1866 CXXThisValue = llvm::UndefValue::get(ConvertTypeForMem(VD->getType()));
1869 if (VD->getType()->isVariablyModifiedType()) {
1870 CGM.ErrorUnsupported(VD, "VLA captured by SEH");
1873 assert((isa<ImplicitParamDecl>(VD) || VD->isLocalVarDeclOrParm()) &&
1874 "captured non-local variable");
1876 // If this decl hasn't been declared yet, it will be declared in the
1878 auto I = ParentCGF.LocalDeclMap.find(VD);
1879 if (I == ParentCGF.LocalDeclMap.end())
1882 Address ParentVar = I->second;
1884 VD, recoverAddrOfEscapedLocal(ParentCGF, ParentVar, ParentFP));
1887 if (Finder.SEHCodeSlot.isValid()) {
1888 SEHCodeSlotStack.push_back(
1889 recoverAddrOfEscapedLocal(ParentCGF, Finder.SEHCodeSlot, ParentFP));
1893 EmitSEHExceptionCodeSave(ParentCGF, ParentFP, EntryFP);
1896 /// Arrange a function prototype that can be called by Windows exception
1897 /// handling personalities. On Win64, the prototype looks like:
1898 /// RetTy func(void *EHPtrs, void *ParentFP);
1899 void CodeGenFunction::startOutlinedSEHHelper(CodeGenFunction &ParentCGF,
1901 const Stmt *OutlinedStmt) {
1902 SourceLocation StartLoc = OutlinedStmt->getBeginLoc();
1904 // Get the mangled function name.
1905 SmallString<128> Name;
1907 llvm::raw_svector_ostream OS(Name);
1908 const NamedDecl *ParentSEHFn = ParentCGF.CurSEHParent;
1909 assert(ParentSEHFn && "No CurSEHParent!");
1910 MangleContext &Mangler = CGM.getCXXABI().getMangleContext();
1912 Mangler.mangleSEHFilterExpression(ParentSEHFn, OS);
1914 Mangler.mangleSEHFinallyBlock(ParentSEHFn, OS);
1917 FunctionArgList Args;
1918 if (CGM.getTarget().getTriple().getArch() != llvm::Triple::x86 || !IsFilter) {
1919 // All SEH finally functions take two parameters. Win64 filters take two
1920 // parameters. Win32 filters take no parameters.
1922 Args.push_back(ImplicitParamDecl::Create(
1923 getContext(), /*DC=*/nullptr, StartLoc,
1924 &getContext().Idents.get("exception_pointers"),
1925 getContext().VoidPtrTy, ImplicitParamDecl::Other));
1927 Args.push_back(ImplicitParamDecl::Create(
1928 getContext(), /*DC=*/nullptr, StartLoc,
1929 &getContext().Idents.get("abnormal_termination"),
1930 getContext().UnsignedCharTy, ImplicitParamDecl::Other));
1932 Args.push_back(ImplicitParamDecl::Create(
1933 getContext(), /*DC=*/nullptr, StartLoc,
1934 &getContext().Idents.get("frame_pointer"), getContext().VoidPtrTy,
1935 ImplicitParamDecl::Other));
1938 QualType RetTy = IsFilter ? getContext().LongTy : getContext().VoidTy;
1940 const CGFunctionInfo &FnInfo =
1941 CGM.getTypes().arrangeBuiltinFunctionDeclaration(RetTy, Args);
1943 llvm::FunctionType *FnTy = CGM.getTypes().GetFunctionType(FnInfo);
1944 llvm::Function *Fn = llvm::Function::Create(
1945 FnTy, llvm::GlobalValue::InternalLinkage, Name.str(), &CGM.getModule());
1947 IsOutlinedSEHHelper = true;
1949 StartFunction(GlobalDecl(), RetTy, Fn, FnInfo, Args,
1950 OutlinedStmt->getBeginLoc(), OutlinedStmt->getBeginLoc());
1951 CurSEHParent = ParentCGF.CurSEHParent;
1953 CGM.SetInternalFunctionAttributes(GlobalDecl(), CurFn, FnInfo);
1954 EmitCapturedLocals(ParentCGF, OutlinedStmt, IsFilter);
1957 /// Create a stub filter function that will ultimately hold the code of the
1958 /// filter expression. The EH preparation passes in LLVM will outline the code
1959 /// from the main function body into this stub.
1961 CodeGenFunction::GenerateSEHFilterFunction(CodeGenFunction &ParentCGF,
1962 const SEHExceptStmt &Except) {
1963 const Expr *FilterExpr = Except.getFilterExpr();
1964 startOutlinedSEHHelper(ParentCGF, true, FilterExpr);
1966 // Emit the original filter expression, convert to i32, and return.
1967 llvm::Value *R = EmitScalarExpr(FilterExpr);
1968 R = Builder.CreateIntCast(R, ConvertType(getContext().LongTy),
1969 FilterExpr->getType()->isSignedIntegerType());
1970 Builder.CreateStore(R, ReturnValue);
1972 FinishFunction(FilterExpr->getEndLoc());
1978 CodeGenFunction::GenerateSEHFinallyFunction(CodeGenFunction &ParentCGF,
1979 const SEHFinallyStmt &Finally) {
1980 const Stmt *FinallyBlock = Finally.getBlock();
1981 startOutlinedSEHHelper(ParentCGF, false, FinallyBlock);
1983 // Emit the original filter expression, convert to i32, and return.
1984 EmitStmt(FinallyBlock);
1986 FinishFunction(FinallyBlock->getEndLoc());
1991 void CodeGenFunction::EmitSEHExceptionCodeSave(CodeGenFunction &ParentCGF,
1992 llvm::Value *ParentFP,
1993 llvm::Value *EntryFP) {
1994 // Get the pointer to the EXCEPTION_POINTERS struct. This is returned by the
1995 // __exception_info intrinsic.
1996 if (CGM.getTarget().getTriple().getArch() != llvm::Triple::x86) {
1997 // On Win64, the info is passed as the first parameter to the filter.
1998 SEHInfo = &*CurFn->arg_begin();
1999 SEHCodeSlotStack.push_back(
2000 CreateMemTemp(getContext().IntTy, "__exception_code"));
2002 // On Win32, the EBP on entry to the filter points to the end of an
2003 // exception registration object. It contains 6 32-bit fields, and the info
2004 // pointer is stored in the second field. So, GEP 20 bytes backwards and
2005 // load the pointer.
2006 SEHInfo = Builder.CreateConstInBoundsGEP1_32(Int8Ty, EntryFP, -20);
2007 SEHInfo = Builder.CreateBitCast(SEHInfo, Int8PtrTy->getPointerTo());
2008 SEHInfo = Builder.CreateAlignedLoad(Int8PtrTy, SEHInfo, getPointerAlign());
2009 SEHCodeSlotStack.push_back(recoverAddrOfEscapedLocal(
2010 ParentCGF, ParentCGF.SEHCodeSlotStack.back(), ParentFP));
2013 // Save the exception code in the exception slot to unify exception access in
2014 // the filter function and the landing pad.
2015 // struct EXCEPTION_POINTERS {
2016 // EXCEPTION_RECORD *ExceptionRecord;
2017 // CONTEXT *ContextRecord;
2019 // int exceptioncode = exception_pointers->ExceptionRecord->ExceptionCode;
2020 llvm::Type *RecordTy = CGM.Int32Ty->getPointerTo();
2021 llvm::Type *PtrsTy = llvm::StructType::get(RecordTy, CGM.VoidPtrTy);
2022 llvm::Value *Ptrs = Builder.CreateBitCast(SEHInfo, PtrsTy->getPointerTo());
2023 llvm::Value *Rec = Builder.CreateStructGEP(PtrsTy, Ptrs, 0);
2024 Rec = Builder.CreateAlignedLoad(Rec, getPointerAlign());
2025 llvm::Value *Code = Builder.CreateAlignedLoad(Rec, getIntAlign());
2026 assert(!SEHCodeSlotStack.empty() && "emitting EH code outside of __except");
2027 Builder.CreateStore(Code, SEHCodeSlotStack.back());
2030 llvm::Value *CodeGenFunction::EmitSEHExceptionInfo() {
2031 // Sema should diagnose calling this builtin outside of a filter context, but
2032 // don't crash if we screw up.
2034 return llvm::UndefValue::get(Int8PtrTy);
2035 assert(SEHInfo->getType() == Int8PtrTy);
2039 llvm::Value *CodeGenFunction::EmitSEHExceptionCode() {
2040 assert(!SEHCodeSlotStack.empty() && "emitting EH code outside of __except");
2041 return Builder.CreateLoad(SEHCodeSlotStack.back());
2044 llvm::Value *CodeGenFunction::EmitSEHAbnormalTermination() {
2045 // Abnormal termination is just the first parameter to the outlined finally
2047 auto AI = CurFn->arg_begin();
2048 return Builder.CreateZExt(&*AI, Int32Ty);
2051 void CodeGenFunction::pushSEHCleanup(CleanupKind Kind,
2052 llvm::Function *FinallyFunc) {
2053 EHStack.pushCleanup<PerformSEHFinally>(Kind, FinallyFunc);
2056 void CodeGenFunction::EnterSEHTryStmt(const SEHTryStmt &S) {
2057 CodeGenFunction HelperCGF(CGM, /*suppressNewContext=*/true);
2058 HelperCGF.ParentCGF = this;
2059 if (const SEHFinallyStmt *Finally = S.getFinallyHandler()) {
2060 // Outline the finally block.
2061 llvm::Function *FinallyFunc =
2062 HelperCGF.GenerateSEHFinallyFunction(*this, *Finally);
2064 // Push a cleanup for __finally blocks.
2065 EHStack.pushCleanup<PerformSEHFinally>(NormalAndEHCleanup, FinallyFunc);
2069 // Otherwise, we must have an __except block.
2070 const SEHExceptStmt *Except = S.getExceptHandler();
2072 EHCatchScope *CatchScope = EHStack.pushCatch(1);
2073 SEHCodeSlotStack.push_back(
2074 CreateMemTemp(getContext().IntTy, "__exception_code"));
2076 // If the filter is known to evaluate to 1, then we can use the clause
2077 // "catch i8* null". We can't do this on x86 because the filter has to save
2078 // the exception code.
2080 ConstantEmitter(*this).tryEmitAbstract(Except->getFilterExpr(),
2081 getContext().IntTy);
2082 if (CGM.getTarget().getTriple().getArch() != llvm::Triple::x86 && C &&
2084 CatchScope->setCatchAllHandler(0, createBasicBlock("__except"));
2088 // In general, we have to emit an outlined filter function. Use the function
2089 // in place of the RTTI typeinfo global that C++ EH uses.
2090 llvm::Function *FilterFunc =
2091 HelperCGF.GenerateSEHFilterFunction(*this, *Except);
2092 llvm::Constant *OpaqueFunc =
2093 llvm::ConstantExpr::getBitCast(FilterFunc, Int8PtrTy);
2094 CatchScope->setHandler(0, OpaqueFunc, createBasicBlock("__except.ret"));
2097 void CodeGenFunction::ExitSEHTryStmt(const SEHTryStmt &S) {
2098 // Just pop the cleanup if it's a __finally block.
2099 if (S.getFinallyHandler()) {
2104 // Otherwise, we must have an __except block.
2105 const SEHExceptStmt *Except = S.getExceptHandler();
2106 assert(Except && "__try must have __finally xor __except");
2107 EHCatchScope &CatchScope = cast<EHCatchScope>(*EHStack.begin());
2109 // Don't emit the __except block if the __try block lacked invokes.
2110 // TODO: Model unwind edges from instructions, either with iload / istore or
2111 // a try body function.
2112 if (!CatchScope.hasEHBranches()) {
2113 CatchScope.clearHandlerBlocks();
2115 SEHCodeSlotStack.pop_back();
2119 // The fall-through block.
2120 llvm::BasicBlock *ContBB = createBasicBlock("__try.cont");
2122 // We just emitted the body of the __try; jump to the continue block.
2123 if (HaveInsertPoint())
2124 Builder.CreateBr(ContBB);
2126 // Check if our filter function returned true.
2127 emitCatchDispatchBlock(*this, CatchScope);
2129 // Grab the block before we pop the handler.
2130 llvm::BasicBlock *CatchPadBB = CatchScope.getHandler(0).Block;
2133 EmitBlockAfterUses(CatchPadBB);
2135 // __except blocks don't get outlined into funclets, so immediately do a
2137 llvm::CatchPadInst *CPI =
2138 cast<llvm::CatchPadInst>(CatchPadBB->getFirstNonPHI());
2139 llvm::BasicBlock *ExceptBB = createBasicBlock("__except");
2140 Builder.CreateCatchRet(CPI, ExceptBB);
2141 EmitBlock(ExceptBB);
2143 // On Win64, the exception code is returned in EAX. Copy it into the slot.
2144 if (CGM.getTarget().getTriple().getArch() != llvm::Triple::x86) {
2145 llvm::Function *SEHCodeIntrin =
2146 CGM.getIntrinsic(llvm::Intrinsic::eh_exceptioncode);
2147 llvm::Value *Code = Builder.CreateCall(SEHCodeIntrin, {CPI});
2148 Builder.CreateStore(Code, SEHCodeSlotStack.back());
2151 // Emit the __except body.
2152 EmitStmt(Except->getBlock());
2154 // End the lifetime of the exception code.
2155 SEHCodeSlotStack.pop_back();
2157 if (HaveInsertPoint())
2158 Builder.CreateBr(ContBB);
2163 void CodeGenFunction::EmitSEHLeaveStmt(const SEHLeaveStmt &S) {
2164 // If this code is reachable then emit a stop point (if generating
2165 // debug info). We have to do this ourselves because we are on the
2166 // "simple" statement path.
2167 if (HaveInsertPoint())
2170 // This must be a __leave from a __finally block, which we warn on and is UB.
2171 // Just emit unreachable.
2172 if (!isSEHTryScope()) {
2173 Builder.CreateUnreachable();
2174 Builder.ClearInsertionPoint();
2178 EmitBranchThroughCleanup(*SEHTryEpilogueStack.back());