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/TargetBuiltins.h"
24 #include "llvm/IR/IntrinsicInst.h"
25 #include "llvm/IR/Intrinsics.h"
26 #include "llvm/IR/IntrinsicsWebAssembly.h"
27 #include "llvm/Support/SaveAndRestore.h"
29 using namespace clang;
30 using namespace CodeGen;
32 static llvm::FunctionCallee getFreeExceptionFn(CodeGenModule &CGM) {
33 // void __cxa_free_exception(void *thrown_exception);
35 llvm::FunctionType *FTy =
36 llvm::FunctionType::get(CGM.VoidTy, CGM.Int8PtrTy, /*isVarArg=*/false);
38 return CGM.CreateRuntimeFunction(FTy, "__cxa_free_exception");
41 static llvm::FunctionCallee getUnexpectedFn(CodeGenModule &CGM) {
42 // void __cxa_call_unexpected(void *thrown_exception);
44 llvm::FunctionType *FTy =
45 llvm::FunctionType::get(CGM.VoidTy, CGM.Int8PtrTy, /*isVarArg=*/false);
47 return CGM.CreateRuntimeFunction(FTy, "__cxa_call_unexpected");
50 llvm::FunctionCallee CodeGenModule::getTerminateFn() {
51 // void __terminate();
53 llvm::FunctionType *FTy =
54 llvm::FunctionType::get(VoidTy, /*isVarArg=*/false);
58 // In C++, use std::terminate().
59 if (getLangOpts().CPlusPlus &&
60 getTarget().getCXXABI().isItaniumFamily()) {
61 name = "_ZSt9terminatev";
62 } else if (getLangOpts().CPlusPlus &&
63 getTarget().getCXXABI().isMicrosoft()) {
64 if (getLangOpts().isCompatibleWithMSVC(LangOptions::MSVC2015))
65 name = "__std_terminate";
67 name = "?terminate@@YAXXZ";
68 } else if (getLangOpts().ObjC &&
69 getLangOpts().ObjCRuntime.hasTerminate())
70 name = "objc_terminate";
73 return CreateRuntimeFunction(FTy, name);
76 static llvm::FunctionCallee getCatchallRethrowFn(CodeGenModule &CGM,
78 llvm::FunctionType *FTy =
79 llvm::FunctionType::get(CGM.VoidTy, CGM.Int8PtrTy, /*isVarArg=*/false);
81 return CGM.CreateRuntimeFunction(FTy, Name);
84 const EHPersonality EHPersonality::GNU_C = { "__gcc_personality_v0", nullptr };
86 EHPersonality::GNU_C_SJLJ = { "__gcc_personality_sj0", nullptr };
88 EHPersonality::GNU_C_SEH = { "__gcc_personality_seh0", nullptr };
90 EHPersonality::NeXT_ObjC = { "__objc_personality_v0", nullptr };
92 EHPersonality::GNU_CPlusPlus = { "__gxx_personality_v0", nullptr };
94 EHPersonality::GNU_CPlusPlus_SJLJ = { "__gxx_personality_sj0", nullptr };
96 EHPersonality::GNU_CPlusPlus_SEH = { "__gxx_personality_seh0", nullptr };
98 EHPersonality::GNU_ObjC = {"__gnu_objc_personality_v0", "objc_exception_throw"};
100 EHPersonality::GNU_ObjC_SJLJ = {"__gnu_objc_personality_sj0", "objc_exception_throw"};
102 EHPersonality::GNU_ObjC_SEH = {"__gnu_objc_personality_seh0", "objc_exception_throw"};
104 EHPersonality::GNU_ObjCXX = { "__gnustep_objcxx_personality_v0", nullptr };
106 EHPersonality::GNUstep_ObjC = { "__gnustep_objc_personality_v0", nullptr };
108 EHPersonality::MSVC_except_handler = { "_except_handler3", nullptr };
110 EHPersonality::MSVC_C_specific_handler = { "__C_specific_handler", nullptr };
112 EHPersonality::MSVC_CxxFrameHandler3 = { "__CxxFrameHandler3", nullptr };
114 EHPersonality::GNU_Wasm_CPlusPlus = { "__gxx_wasm_personality_v0", nullptr };
116 static const EHPersonality &getCPersonality(const TargetInfo &Target,
117 const LangOptions &L) {
118 const llvm::Triple &T = Target.getTriple();
119 if (T.isWindowsMSVCEnvironment())
120 return EHPersonality::MSVC_CxxFrameHandler3;
121 if (L.SjLjExceptions)
122 return EHPersonality::GNU_C_SJLJ;
123 if (L.DWARFExceptions)
124 return EHPersonality::GNU_C;
126 return EHPersonality::GNU_C_SEH;
127 return EHPersonality::GNU_C;
130 static const EHPersonality &getObjCPersonality(const TargetInfo &Target,
131 const LangOptions &L) {
132 const llvm::Triple &T = Target.getTriple();
133 if (T.isWindowsMSVCEnvironment())
134 return EHPersonality::MSVC_CxxFrameHandler3;
136 switch (L.ObjCRuntime.getKind()) {
137 case ObjCRuntime::FragileMacOSX:
138 return getCPersonality(Target, L);
139 case ObjCRuntime::MacOSX:
140 case ObjCRuntime::iOS:
141 case ObjCRuntime::WatchOS:
142 return EHPersonality::NeXT_ObjC;
143 case ObjCRuntime::GNUstep:
144 if (L.ObjCRuntime.getVersion() >= VersionTuple(1, 7))
145 return EHPersonality::GNUstep_ObjC;
147 case ObjCRuntime::GCC:
148 case ObjCRuntime::ObjFW:
149 if (L.SjLjExceptions)
150 return EHPersonality::GNU_ObjC_SJLJ;
152 return EHPersonality::GNU_ObjC_SEH;
153 return EHPersonality::GNU_ObjC;
155 llvm_unreachable("bad runtime kind");
158 static const EHPersonality &getCXXPersonality(const TargetInfo &Target,
159 const LangOptions &L) {
160 const llvm::Triple &T = Target.getTriple();
161 if (T.isWindowsMSVCEnvironment())
162 return EHPersonality::MSVC_CxxFrameHandler3;
163 if (L.SjLjExceptions)
164 return EHPersonality::GNU_CPlusPlus_SJLJ;
165 if (L.DWARFExceptions)
166 return EHPersonality::GNU_CPlusPlus;
168 return EHPersonality::GNU_CPlusPlus_SEH;
169 if (L.WasmExceptions)
170 return EHPersonality::GNU_Wasm_CPlusPlus;
171 return EHPersonality::GNU_CPlusPlus;
174 /// Determines the personality function to use when both C++
175 /// and Objective-C exceptions are being caught.
176 static const EHPersonality &getObjCXXPersonality(const TargetInfo &Target,
177 const LangOptions &L) {
178 if (Target.getTriple().isWindowsMSVCEnvironment())
179 return EHPersonality::MSVC_CxxFrameHandler3;
181 switch (L.ObjCRuntime.getKind()) {
182 // In the fragile ABI, just use C++ exception handling and hope
183 // they're not doing crazy exception mixing.
184 case ObjCRuntime::FragileMacOSX:
185 return getCXXPersonality(Target, L);
187 // The ObjC personality defers to the C++ personality for non-ObjC
188 // handlers. Unlike the C++ case, we use the same personality
189 // function on targets using (backend-driven) SJLJ EH.
190 case ObjCRuntime::MacOSX:
191 case ObjCRuntime::iOS:
192 case ObjCRuntime::WatchOS:
193 return getObjCPersonality(Target, L);
195 case ObjCRuntime::GNUstep:
196 return EHPersonality::GNU_ObjCXX;
198 // The GCC runtime's personality function inherently doesn't support
199 // mixed EH. Use the ObjC personality just to avoid returning null.
200 case ObjCRuntime::GCC:
201 case ObjCRuntime::ObjFW:
202 return getObjCPersonality(Target, L);
204 llvm_unreachable("bad runtime kind");
207 static const EHPersonality &getSEHPersonalityMSVC(const llvm::Triple &T) {
208 if (T.getArch() == llvm::Triple::x86)
209 return EHPersonality::MSVC_except_handler;
210 return EHPersonality::MSVC_C_specific_handler;
213 const EHPersonality &EHPersonality::get(CodeGenModule &CGM,
214 const FunctionDecl *FD) {
215 const llvm::Triple &T = CGM.getTarget().getTriple();
216 const LangOptions &L = CGM.getLangOpts();
217 const TargetInfo &Target = CGM.getTarget();
219 // Functions using SEH get an SEH personality.
220 if (FD && FD->usesSEHTry())
221 return getSEHPersonalityMSVC(T);
224 return L.CPlusPlus ? getObjCXXPersonality(Target, L)
225 : getObjCPersonality(Target, L);
226 return L.CPlusPlus ? getCXXPersonality(Target, L)
227 : getCPersonality(Target, L);
230 const EHPersonality &EHPersonality::get(CodeGenFunction &CGF) {
231 const auto *FD = CGF.CurCodeDecl;
232 // For outlined finallys and filters, use the SEH personality in case they
233 // contain more SEH. This mostly only affects finallys. Filters could
234 // hypothetically use gnu statement expressions to sneak in nested SEH.
235 FD = FD ? FD : CGF.CurSEHParent;
236 return get(CGF.CGM, dyn_cast_or_null<FunctionDecl>(FD));
239 static llvm::FunctionCallee getPersonalityFn(CodeGenModule &CGM,
240 const EHPersonality &Personality) {
241 return CGM.CreateRuntimeFunction(llvm::FunctionType::get(CGM.Int32Ty, true),
242 Personality.PersonalityFn,
243 llvm::AttributeList(), /*Local=*/true);
246 static llvm::Constant *getOpaquePersonalityFn(CodeGenModule &CGM,
247 const EHPersonality &Personality) {
248 llvm::FunctionCallee Fn = getPersonalityFn(CGM, Personality);
249 llvm::PointerType* Int8PtrTy = llvm::PointerType::get(
250 llvm::Type::getInt8Ty(CGM.getLLVMContext()),
251 CGM.getDataLayout().getProgramAddressSpace());
253 return llvm::ConstantExpr::getBitCast(cast<llvm::Constant>(Fn.getCallee()),
257 /// Check whether a landingpad instruction only uses C++ features.
258 static bool LandingPadHasOnlyCXXUses(llvm::LandingPadInst *LPI) {
259 for (unsigned I = 0, E = LPI->getNumClauses(); I != E; ++I) {
260 // Look for something that would've been returned by the ObjC
261 // runtime's GetEHType() method.
262 llvm::Value *Val = LPI->getClause(I)->stripPointerCasts();
263 if (LPI->isCatch(I)) {
264 // Check if the catch value has the ObjC prefix.
265 if (llvm::GlobalVariable *GV = dyn_cast<llvm::GlobalVariable>(Val))
266 // ObjC EH selector entries are always global variables with
267 // names starting like this.
268 if (GV->getName().startswith("OBJC_EHTYPE"))
271 // Check if any of the filter values have the ObjC prefix.
272 llvm::Constant *CVal = cast<llvm::Constant>(Val);
273 for (llvm::User::op_iterator
274 II = CVal->op_begin(), IE = CVal->op_end(); II != IE; ++II) {
275 if (llvm::GlobalVariable *GV =
276 cast<llvm::GlobalVariable>((*II)->stripPointerCasts()))
277 // ObjC EH selector entries are always global variables with
278 // names starting like this.
279 if (GV->getName().startswith("OBJC_EHTYPE"))
287 /// Check whether a personality function could reasonably be swapped
288 /// for a C++ personality function.
289 static bool PersonalityHasOnlyCXXUses(llvm::Constant *Fn) {
290 for (llvm::User *U : Fn->users()) {
291 // Conditionally white-list bitcasts.
292 if (llvm::ConstantExpr *CE = dyn_cast<llvm::ConstantExpr>(U)) {
293 if (CE->getOpcode() != llvm::Instruction::BitCast) return false;
294 if (!PersonalityHasOnlyCXXUses(CE))
299 // Otherwise it must be a function.
300 llvm::Function *F = dyn_cast<llvm::Function>(U);
301 if (!F) return false;
303 for (auto BB = F->begin(), E = F->end(); BB != E; ++BB) {
304 if (BB->isLandingPad())
305 if (!LandingPadHasOnlyCXXUses(BB->getLandingPadInst()))
313 /// Try to use the C++ personality function in ObjC++. Not doing this
314 /// can cause some incompatibilities with gcc, which is more
315 /// aggressive about only using the ObjC++ personality in a function
316 /// when it really needs it.
317 void CodeGenModule::SimplifyPersonality() {
318 // If we're not in ObjC++ -fexceptions, there's nothing to do.
319 if (!LangOpts.CPlusPlus || !LangOpts.ObjC || !LangOpts.Exceptions)
322 // Both the problem this endeavors to fix and the way the logic
323 // above works is specific to the NeXT runtime.
324 if (!LangOpts.ObjCRuntime.isNeXTFamily())
327 const EHPersonality &ObjCXX = EHPersonality::get(*this, /*FD=*/nullptr);
328 const EHPersonality &CXX = getCXXPersonality(getTarget(), LangOpts);
332 assert(std::strcmp(ObjCXX.PersonalityFn, CXX.PersonalityFn) != 0 &&
333 "Different EHPersonalities using the same personality function.");
335 llvm::Function *Fn = getModule().getFunction(ObjCXX.PersonalityFn);
337 // Nothing to do if it's unused.
338 if (!Fn || Fn->use_empty()) return;
340 // Can't do the optimization if it has non-C++ uses.
341 if (!PersonalityHasOnlyCXXUses(Fn)) return;
343 // Create the C++ personality function and kill off the old
345 llvm::FunctionCallee CXXFn = getPersonalityFn(*this, CXX);
347 // This can happen if the user is screwing with us.
348 if (Fn->getType() != CXXFn.getCallee()->getType())
351 Fn->replaceAllUsesWith(CXXFn.getCallee());
352 Fn->eraseFromParent();
355 /// Returns the value to inject into a selector to indicate the
356 /// presence of a catch-all.
357 static llvm::Constant *getCatchAllValue(CodeGenFunction &CGF) {
358 // Possibly we should use @llvm.eh.catch.all.value here.
359 return llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
363 /// A cleanup to free the exception object if its initialization
365 struct FreeException final : EHScopeStack::Cleanup {
367 FreeException(llvm::Value *exn) : exn(exn) {}
368 void Emit(CodeGenFunction &CGF, Flags flags) override {
369 CGF.EmitNounwindRuntimeCall(getFreeExceptionFn(CGF.CGM), exn);
372 } // end anonymous namespace
374 // Emits an exception expression into the given location. This
375 // differs from EmitAnyExprToMem only in that, if a final copy-ctor
376 // call is required, an exception within that copy ctor causes
377 // std::terminate to be invoked.
378 void CodeGenFunction::EmitAnyExprToExn(const Expr *e, Address addr) {
379 // Make sure the exception object is cleaned up if there's an
380 // exception during initialization.
381 pushFullExprCleanup<FreeException>(EHCleanup, addr.getPointer());
382 EHScopeStack::stable_iterator cleanup = EHStack.stable_begin();
384 // __cxa_allocate_exception returns a void*; we need to cast this
385 // to the appropriate type for the object.
386 llvm::Type *ty = ConvertTypeForMem(e->getType())->getPointerTo();
387 Address typedAddr = Builder.CreateBitCast(addr, ty);
389 // FIXME: this isn't quite right! If there's a final unelided call
390 // to a copy constructor, then according to [except.terminate]p1 we
391 // must call std::terminate() if that constructor throws, because
392 // technically that copy occurs after the exception expression is
393 // evaluated but before the exception is caught. But the best way
394 // to handle that is to teach EmitAggExpr to do the final copy
395 // differently if it can't be elided.
396 EmitAnyExprToMem(e, typedAddr, e->getType().getQualifiers(),
399 // Deactivate the cleanup block.
400 DeactivateCleanupBlock(cleanup,
401 cast<llvm::Instruction>(typedAddr.getPointer()));
404 Address CodeGenFunction::getExceptionSlot() {
406 ExceptionSlot = CreateTempAlloca(Int8PtrTy, "exn.slot");
407 return Address(ExceptionSlot, getPointerAlign());
410 Address CodeGenFunction::getEHSelectorSlot() {
412 EHSelectorSlot = CreateTempAlloca(Int32Ty, "ehselector.slot");
413 return Address(EHSelectorSlot, CharUnits::fromQuantity(4));
416 llvm::Value *CodeGenFunction::getExceptionFromSlot() {
417 return Builder.CreateLoad(getExceptionSlot(), "exn");
420 llvm::Value *CodeGenFunction::getSelectorFromSlot() {
421 return Builder.CreateLoad(getEHSelectorSlot(), "sel");
424 void CodeGenFunction::EmitCXXThrowExpr(const CXXThrowExpr *E,
425 bool KeepInsertionPoint) {
426 if (const Expr *SubExpr = E->getSubExpr()) {
427 QualType ThrowType = SubExpr->getType();
428 if (ThrowType->isObjCObjectPointerType()) {
429 const Stmt *ThrowStmt = E->getSubExpr();
430 const ObjCAtThrowStmt S(E->getExprLoc(), const_cast<Stmt *>(ThrowStmt));
431 CGM.getObjCRuntime().EmitThrowStmt(*this, S, false);
433 CGM.getCXXABI().emitThrow(*this, E);
436 CGM.getCXXABI().emitRethrow(*this, /*isNoReturn=*/true);
439 // throw is an expression, and the expression emitters expect us
440 // to leave ourselves at a valid insertion point.
441 if (KeepInsertionPoint)
442 EmitBlock(createBasicBlock("throw.cont"));
445 void CodeGenFunction::EmitStartEHSpec(const Decl *D) {
446 if (!CGM.getLangOpts().CXXExceptions)
449 const FunctionDecl* FD = dyn_cast_or_null<FunctionDecl>(D);
451 // Check if CapturedDecl is nothrow and create terminate scope for it.
452 if (const CapturedDecl* CD = dyn_cast_or_null<CapturedDecl>(D)) {
454 EHStack.pushTerminate();
458 const FunctionProtoType *Proto = FD->getType()->getAs<FunctionProtoType>();
462 ExceptionSpecificationType EST = Proto->getExceptionSpecType();
463 if (isNoexceptExceptionSpec(EST) && Proto->canThrow() == CT_Cannot) {
464 // noexcept functions are simple terminate scopes.
465 EHStack.pushTerminate();
466 } else if (EST == EST_Dynamic || EST == EST_DynamicNone) {
467 // TODO: Revisit exception specifications for the MS ABI. There is a way to
468 // encode these in an object file but MSVC doesn't do anything with it.
469 if (getTarget().getCXXABI().isMicrosoft())
471 unsigned NumExceptions = Proto->getNumExceptions();
472 EHFilterScope *Filter = EHStack.pushFilter(NumExceptions);
474 for (unsigned I = 0; I != NumExceptions; ++I) {
475 QualType Ty = Proto->getExceptionType(I);
476 QualType ExceptType = Ty.getNonReferenceType().getUnqualifiedType();
477 llvm::Value *EHType = CGM.GetAddrOfRTTIDescriptor(ExceptType,
479 Filter->setFilter(I, EHType);
484 /// Emit the dispatch block for a filter scope if necessary.
485 static void emitFilterDispatchBlock(CodeGenFunction &CGF,
486 EHFilterScope &filterScope) {
487 llvm::BasicBlock *dispatchBlock = filterScope.getCachedEHDispatchBlock();
488 if (!dispatchBlock) return;
489 if (dispatchBlock->use_empty()) {
490 delete dispatchBlock;
494 CGF.EmitBlockAfterUses(dispatchBlock);
496 // If this isn't a catch-all filter, we need to check whether we got
497 // here because the filter triggered.
498 if (filterScope.getNumFilters()) {
499 // Load the selector value.
500 llvm::Value *selector = CGF.getSelectorFromSlot();
501 llvm::BasicBlock *unexpectedBB = CGF.createBasicBlock("ehspec.unexpected");
503 llvm::Value *zero = CGF.Builder.getInt32(0);
504 llvm::Value *failsFilter =
505 CGF.Builder.CreateICmpSLT(selector, zero, "ehspec.fails");
506 CGF.Builder.CreateCondBr(failsFilter, unexpectedBB,
507 CGF.getEHResumeBlock(false));
509 CGF.EmitBlock(unexpectedBB);
512 // Call __cxa_call_unexpected. This doesn't need to be an invoke
513 // because __cxa_call_unexpected magically filters exceptions
514 // according to the last landing pad the exception was thrown
516 llvm::Value *exn = CGF.getExceptionFromSlot();
517 CGF.EmitRuntimeCall(getUnexpectedFn(CGF.CGM), exn)
518 ->setDoesNotReturn();
519 CGF.Builder.CreateUnreachable();
522 void CodeGenFunction::EmitEndEHSpec(const Decl *D) {
523 if (!CGM.getLangOpts().CXXExceptions)
526 const FunctionDecl* FD = dyn_cast_or_null<FunctionDecl>(D);
528 // Check if CapturedDecl is nothrow and pop terminate scope for it.
529 if (const CapturedDecl* CD = dyn_cast_or_null<CapturedDecl>(D)) {
531 EHStack.popTerminate();
535 const FunctionProtoType *Proto = FD->getType()->getAs<FunctionProtoType>();
539 ExceptionSpecificationType EST = Proto->getExceptionSpecType();
540 if (isNoexceptExceptionSpec(EST) && Proto->canThrow() == CT_Cannot) {
541 EHStack.popTerminate();
542 } else if (EST == EST_Dynamic || EST == EST_DynamicNone) {
543 // TODO: Revisit exception specifications for the MS ABI. There is a way to
544 // encode these in an object file but MSVC doesn't do anything with it.
545 if (getTarget().getCXXABI().isMicrosoft())
547 EHFilterScope &filterScope = cast<EHFilterScope>(*EHStack.begin());
548 emitFilterDispatchBlock(*this, filterScope);
553 void CodeGenFunction::EmitCXXTryStmt(const CXXTryStmt &S) {
555 EmitStmt(S.getTryBlock());
559 void CodeGenFunction::EnterCXXTryStmt(const CXXTryStmt &S, bool IsFnTryBlock) {
560 unsigned NumHandlers = S.getNumHandlers();
561 EHCatchScope *CatchScope = EHStack.pushCatch(NumHandlers);
563 for (unsigned I = 0; I != NumHandlers; ++I) {
564 const CXXCatchStmt *C = S.getHandler(I);
566 llvm::BasicBlock *Handler = createBasicBlock("catch");
567 if (C->getExceptionDecl()) {
568 // FIXME: Dropping the reference type on the type into makes it
569 // impossible to correctly implement catch-by-reference
570 // semantics for pointers. Unfortunately, this is what all
571 // existing compilers do, and it's not clear that the standard
572 // personality routine is capable of doing this right. See C++ DR 388:
573 // http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#388
574 Qualifiers CaughtTypeQuals;
575 QualType CaughtType = CGM.getContext().getUnqualifiedArrayType(
576 C->getCaughtType().getNonReferenceType(), CaughtTypeQuals);
578 CatchTypeInfo TypeInfo{nullptr, 0};
579 if (CaughtType->isObjCObjectPointerType())
580 TypeInfo.RTTI = CGM.getObjCRuntime().GetEHType(CaughtType);
582 TypeInfo = CGM.getCXXABI().getAddrOfCXXCatchHandlerType(
583 CaughtType, C->getCaughtType());
584 CatchScope->setHandler(I, TypeInfo, Handler);
586 // No exception decl indicates '...', a catch-all.
587 CatchScope->setHandler(I, CGM.getCXXABI().getCatchAllTypeInfo(), Handler);
593 CodeGenFunction::getEHDispatchBlock(EHScopeStack::stable_iterator si) {
594 if (EHPersonality::get(*this).usesFuncletPads())
595 return getFuncletEHDispatchBlock(si);
597 // The dispatch block for the end of the scope chain is a block that
598 // just resumes unwinding.
599 if (si == EHStack.stable_end())
600 return getEHResumeBlock(true);
602 // Otherwise, we should look at the actual scope.
603 EHScope &scope = *EHStack.find(si);
605 llvm::BasicBlock *dispatchBlock = scope.getCachedEHDispatchBlock();
606 if (!dispatchBlock) {
607 switch (scope.getKind()) {
608 case EHScope::Catch: {
609 // Apply a special case to a single catch-all.
610 EHCatchScope &catchScope = cast<EHCatchScope>(scope);
611 if (catchScope.getNumHandlers() == 1 &&
612 catchScope.getHandler(0).isCatchAll()) {
613 dispatchBlock = catchScope.getHandler(0).Block;
615 // Otherwise, make a dispatch block.
617 dispatchBlock = createBasicBlock("catch.dispatch");
622 case EHScope::Cleanup:
623 dispatchBlock = createBasicBlock("ehcleanup");
626 case EHScope::Filter:
627 dispatchBlock = createBasicBlock("filter.dispatch");
630 case EHScope::Terminate:
631 dispatchBlock = getTerminateHandler();
634 case EHScope::PadEnd:
635 llvm_unreachable("PadEnd unnecessary for Itanium!");
637 scope.setCachedEHDispatchBlock(dispatchBlock);
639 return dispatchBlock;
643 CodeGenFunction::getFuncletEHDispatchBlock(EHScopeStack::stable_iterator SI) {
644 // Returning nullptr indicates that the previous dispatch block should unwind
646 if (SI == EHStack.stable_end())
649 // Otherwise, we should look at the actual scope.
650 EHScope &EHS = *EHStack.find(SI);
652 llvm::BasicBlock *DispatchBlock = EHS.getCachedEHDispatchBlock();
654 return DispatchBlock;
656 if (EHS.getKind() == EHScope::Terminate)
657 DispatchBlock = getTerminateFunclet();
659 DispatchBlock = createBasicBlock();
660 CGBuilderTy Builder(*this, DispatchBlock);
662 switch (EHS.getKind()) {
664 DispatchBlock->setName("catch.dispatch");
667 case EHScope::Cleanup:
668 DispatchBlock->setName("ehcleanup");
671 case EHScope::Filter:
672 llvm_unreachable("exception specifications not handled yet!");
674 case EHScope::Terminate:
675 DispatchBlock->setName("terminate");
678 case EHScope::PadEnd:
679 llvm_unreachable("PadEnd dispatch block missing!");
681 EHS.setCachedEHDispatchBlock(DispatchBlock);
682 return DispatchBlock;
685 /// Check whether this is a non-EH scope, i.e. a scope which doesn't
686 /// affect exception handling. Currently, the only non-EH scopes are
687 /// normal-only cleanup scopes.
688 static bool isNonEHScope(const EHScope &S) {
689 switch (S.getKind()) {
690 case EHScope::Cleanup:
691 return !cast<EHCleanupScope>(S).isEHCleanup();
692 case EHScope::Filter:
694 case EHScope::Terminate:
695 case EHScope::PadEnd:
699 llvm_unreachable("Invalid EHScope Kind!");
702 llvm::BasicBlock *CodeGenFunction::getInvokeDestImpl() {
703 assert(EHStack.requiresLandingPad());
704 assert(!EHStack.empty());
706 // If exceptions are disabled and SEH is not in use, then there is no invoke
707 // destination. SEH "works" even if exceptions are off. In practice, this
708 // means that C++ destructors and other EH cleanups don't run, which is
709 // consistent with MSVC's behavior.
710 const LangOptions &LO = CGM.getLangOpts();
711 if (!LO.Exceptions) {
712 if (!LO.Borland && !LO.MicrosoftExt)
714 if (!currentFunctionUsesSEHTry())
718 // CUDA device code doesn't have exceptions.
719 if (LO.CUDA && LO.CUDAIsDevice)
722 // Check the innermost scope for a cached landing pad. If this is
723 // a non-EH cleanup, we'll check enclosing scopes in EmitLandingPad.
724 llvm::BasicBlock *LP = EHStack.begin()->getCachedLandingPad();
727 const EHPersonality &Personality = EHPersonality::get(*this);
729 if (!CurFn->hasPersonalityFn())
730 CurFn->setPersonalityFn(getOpaquePersonalityFn(CGM, Personality));
732 if (Personality.usesFuncletPads()) {
733 // We don't need separate landing pads in the funclet model.
734 LP = getEHDispatchBlock(EHStack.getInnermostEHScope());
736 // Build the landing pad for this scope.
737 LP = EmitLandingPad();
742 // Cache the landing pad on the innermost scope. If this is a
743 // non-EH scope, cache the landing pad on the enclosing scope, too.
744 for (EHScopeStack::iterator ir = EHStack.begin(); true; ++ir) {
745 ir->setCachedLandingPad(LP);
746 if (!isNonEHScope(*ir)) break;
752 llvm::BasicBlock *CodeGenFunction::EmitLandingPad() {
753 assert(EHStack.requiresLandingPad());
755 EHScope &innermostEHScope = *EHStack.find(EHStack.getInnermostEHScope());
756 switch (innermostEHScope.getKind()) {
757 case EHScope::Terminate:
758 return getTerminateLandingPad();
760 case EHScope::PadEnd:
761 llvm_unreachable("PadEnd unnecessary for Itanium!");
764 case EHScope::Cleanup:
765 case EHScope::Filter:
766 if (llvm::BasicBlock *lpad = innermostEHScope.getCachedLandingPad())
770 // Save the current IR generation state.
771 CGBuilderTy::InsertPoint savedIP = Builder.saveAndClearIP();
772 auto DL = ApplyDebugLocation::CreateDefaultArtificial(*this, CurEHLocation);
774 // Create and configure the landing pad.
775 llvm::BasicBlock *lpad = createBasicBlock("lpad");
778 llvm::LandingPadInst *LPadInst =
779 Builder.CreateLandingPad(llvm::StructType::get(Int8PtrTy, Int32Ty), 0);
781 llvm::Value *LPadExn = Builder.CreateExtractValue(LPadInst, 0);
782 Builder.CreateStore(LPadExn, getExceptionSlot());
783 llvm::Value *LPadSel = Builder.CreateExtractValue(LPadInst, 1);
784 Builder.CreateStore(LPadSel, getEHSelectorSlot());
786 // Save the exception pointer. It's safe to use a single exception
787 // pointer per function because EH cleanups can never have nested
789 // Build the landingpad instruction.
791 // Accumulate all the handlers in scope.
792 bool hasCatchAll = false;
793 bool hasCleanup = false;
794 bool hasFilter = false;
795 SmallVector<llvm::Value*, 4> filterTypes;
796 llvm::SmallPtrSet<llvm::Value*, 4> catchTypes;
797 for (EHScopeStack::iterator I = EHStack.begin(), E = EHStack.end(); I != E;
800 switch (I->getKind()) {
801 case EHScope::Cleanup:
802 // If we have a cleanup, remember that.
803 hasCleanup = (hasCleanup || cast<EHCleanupScope>(*I).isEHCleanup());
806 case EHScope::Filter: {
807 assert(I.next() == EHStack.end() && "EH filter is not end of EH stack");
808 assert(!hasCatchAll && "EH filter reached after catch-all");
810 // Filter scopes get added to the landingpad in weird ways.
811 EHFilterScope &filter = cast<EHFilterScope>(*I);
814 // Add all the filter values.
815 for (unsigned i = 0, e = filter.getNumFilters(); i != e; ++i)
816 filterTypes.push_back(filter.getFilter(i));
820 case EHScope::Terminate:
821 // Terminate scopes are basically catch-alls.
822 assert(!hasCatchAll);
829 case EHScope::PadEnd:
830 llvm_unreachable("PadEnd unnecessary for Itanium!");
833 EHCatchScope &catchScope = cast<EHCatchScope>(*I);
834 for (unsigned hi = 0, he = catchScope.getNumHandlers(); hi != he; ++hi) {
835 EHCatchScope::Handler handler = catchScope.getHandler(hi);
836 assert(handler.Type.Flags == 0 &&
837 "landingpads do not support catch handler flags");
839 // If this is a catch-all, register that and abort.
840 if (!handler.Type.RTTI) {
841 assert(!hasCatchAll);
846 // Check whether we already have a handler for this type.
847 if (catchTypes.insert(handler.Type.RTTI).second)
848 // If not, add it directly to the landingpad.
849 LPadInst->addClause(handler.Type.RTTI);
854 // If we have a catch-all, add null to the landingpad.
855 assert(!(hasCatchAll && hasFilter));
857 LPadInst->addClause(getCatchAllValue(*this));
859 // If we have an EH filter, we need to add those handlers in the
860 // right place in the landingpad, which is to say, at the end.
861 } else if (hasFilter) {
862 // Create a filter expression: a constant array indicating which filter
863 // types there are. The personality routine only lands here if the filter
865 SmallVector<llvm::Constant*, 8> Filters;
866 llvm::ArrayType *AType =
867 llvm::ArrayType::get(!filterTypes.empty() ?
868 filterTypes[0]->getType() : Int8PtrTy,
871 for (unsigned i = 0, e = filterTypes.size(); i != e; ++i)
872 Filters.push_back(cast<llvm::Constant>(filterTypes[i]));
873 llvm::Constant *FilterArray = llvm::ConstantArray::get(AType, Filters);
874 LPadInst->addClause(FilterArray);
876 // Also check whether we need a cleanup.
878 LPadInst->setCleanup(true);
880 // Otherwise, signal that we at least have cleanups.
881 } else if (hasCleanup) {
882 LPadInst->setCleanup(true);
885 assert((LPadInst->getNumClauses() > 0 || LPadInst->isCleanup()) &&
886 "landingpad instruction has no clauses!");
888 // Tell the backend how to generate the landing pad.
889 Builder.CreateBr(getEHDispatchBlock(EHStack.getInnermostEHScope()));
891 // Restore the old IR generation state.
892 Builder.restoreIP(savedIP);
897 static void emitCatchPadBlock(CodeGenFunction &CGF, EHCatchScope &CatchScope) {
898 llvm::BasicBlock *DispatchBlock = CatchScope.getCachedEHDispatchBlock();
899 assert(DispatchBlock);
901 CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveIP();
902 CGF.EmitBlockAfterUses(DispatchBlock);
904 llvm::Value *ParentPad = CGF.CurrentFuncletPad;
906 ParentPad = llvm::ConstantTokenNone::get(CGF.getLLVMContext());
907 llvm::BasicBlock *UnwindBB =
908 CGF.getEHDispatchBlock(CatchScope.getEnclosingEHScope());
910 unsigned NumHandlers = CatchScope.getNumHandlers();
911 llvm::CatchSwitchInst *CatchSwitch =
912 CGF.Builder.CreateCatchSwitch(ParentPad, UnwindBB, NumHandlers);
914 // Test against each of the exception types we claim to catch.
915 for (unsigned I = 0; I < NumHandlers; ++I) {
916 const EHCatchScope::Handler &Handler = CatchScope.getHandler(I);
918 CatchTypeInfo TypeInfo = Handler.Type;
920 TypeInfo.RTTI = llvm::Constant::getNullValue(CGF.VoidPtrTy);
922 CGF.Builder.SetInsertPoint(Handler.Block);
924 if (EHPersonality::get(CGF).isMSVCXXPersonality()) {
925 CGF.Builder.CreateCatchPad(
926 CatchSwitch, {TypeInfo.RTTI, CGF.Builder.getInt32(TypeInfo.Flags),
927 llvm::Constant::getNullValue(CGF.VoidPtrTy)});
929 CGF.Builder.CreateCatchPad(CatchSwitch, {TypeInfo.RTTI});
932 CatchSwitch->addHandler(Handler.Block);
934 CGF.Builder.restoreIP(SavedIP);
937 // Wasm uses Windows-style EH instructions, but it merges all catch clauses into
938 // one big catchpad, within which we use Itanium's landingpad-style selector
939 // comparison instructions.
940 static void emitWasmCatchPadBlock(CodeGenFunction &CGF,
941 EHCatchScope &CatchScope) {
942 llvm::BasicBlock *DispatchBlock = CatchScope.getCachedEHDispatchBlock();
943 assert(DispatchBlock);
945 CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveIP();
946 CGF.EmitBlockAfterUses(DispatchBlock);
948 llvm::Value *ParentPad = CGF.CurrentFuncletPad;
950 ParentPad = llvm::ConstantTokenNone::get(CGF.getLLVMContext());
951 llvm::BasicBlock *UnwindBB =
952 CGF.getEHDispatchBlock(CatchScope.getEnclosingEHScope());
954 unsigned NumHandlers = CatchScope.getNumHandlers();
955 llvm::CatchSwitchInst *CatchSwitch =
956 CGF.Builder.CreateCatchSwitch(ParentPad, UnwindBB, NumHandlers);
958 // We don't use a landingpad instruction, so generate intrinsic calls to
959 // provide exception and selector values.
960 llvm::BasicBlock *WasmCatchStartBlock = CGF.createBasicBlock("catch.start");
961 CatchSwitch->addHandler(WasmCatchStartBlock);
962 CGF.EmitBlockAfterUses(WasmCatchStartBlock);
964 // Create a catchpad instruction.
965 SmallVector<llvm::Value *, 4> CatchTypes;
966 for (unsigned I = 0, E = NumHandlers; I < E; ++I) {
967 const EHCatchScope::Handler &Handler = CatchScope.getHandler(I);
968 CatchTypeInfo TypeInfo = Handler.Type;
970 TypeInfo.RTTI = llvm::Constant::getNullValue(CGF.VoidPtrTy);
971 CatchTypes.push_back(TypeInfo.RTTI);
973 auto *CPI = CGF.Builder.CreateCatchPad(CatchSwitch, CatchTypes);
975 // Create calls to wasm.get.exception and wasm.get.ehselector intrinsics.
976 // Before they are lowered appropriately later, they provide values for the
977 // exception and selector.
978 llvm::Function *GetExnFn =
979 CGF.CGM.getIntrinsic(llvm::Intrinsic::wasm_get_exception);
980 llvm::Function *GetSelectorFn =
981 CGF.CGM.getIntrinsic(llvm::Intrinsic::wasm_get_ehselector);
982 llvm::CallInst *Exn = CGF.Builder.CreateCall(GetExnFn, CPI);
983 CGF.Builder.CreateStore(Exn, CGF.getExceptionSlot());
984 llvm::CallInst *Selector = CGF.Builder.CreateCall(GetSelectorFn, CPI);
986 llvm::Function *TypeIDFn = CGF.CGM.getIntrinsic(llvm::Intrinsic::eh_typeid_for);
988 // If there's only a single catch-all, branch directly to its handler.
989 if (CatchScope.getNumHandlers() == 1 &&
990 CatchScope.getHandler(0).isCatchAll()) {
991 CGF.Builder.CreateBr(CatchScope.getHandler(0).Block);
992 CGF.Builder.restoreIP(SavedIP);
996 // Test against each of the exception types we claim to catch.
997 for (unsigned I = 0, E = NumHandlers;; ++I) {
998 assert(I < E && "ran off end of handlers!");
999 const EHCatchScope::Handler &Handler = CatchScope.getHandler(I);
1000 CatchTypeInfo TypeInfo = Handler.Type;
1002 TypeInfo.RTTI = llvm::Constant::getNullValue(CGF.VoidPtrTy);
1004 // Figure out the next block.
1005 llvm::BasicBlock *NextBlock;
1007 bool EmitNextBlock = false, NextIsEnd = false;
1009 // If this is the last handler, we're at the end, and the next block is a
1010 // block that contains a call to the rethrow function, so we can unwind to
1011 // the enclosing EH scope. The call itself will be generated later.
1013 NextBlock = CGF.createBasicBlock("rethrow");
1014 EmitNextBlock = true;
1017 // If the next handler is a catch-all, we're at the end, and the
1018 // next block is that handler.
1019 } else if (CatchScope.getHandler(I + 1).isCatchAll()) {
1020 NextBlock = CatchScope.getHandler(I + 1).Block;
1023 // Otherwise, we're not at the end and we need a new block.
1025 NextBlock = CGF.createBasicBlock("catch.fallthrough");
1026 EmitNextBlock = true;
1029 // Figure out the catch type's index in the LSDA's type table.
1030 llvm::CallInst *TypeIndex = CGF.Builder.CreateCall(TypeIDFn, TypeInfo.RTTI);
1031 TypeIndex->setDoesNotThrow();
1033 llvm::Value *MatchesTypeIndex =
1034 CGF.Builder.CreateICmpEQ(Selector, TypeIndex, "matches");
1035 CGF.Builder.CreateCondBr(MatchesTypeIndex, Handler.Block, NextBlock);
1038 CGF.EmitBlock(NextBlock);
1043 CGF.Builder.restoreIP(SavedIP);
1046 /// Emit the structure of the dispatch block for the given catch scope.
1047 /// It is an invariant that the dispatch block already exists.
1048 static void emitCatchDispatchBlock(CodeGenFunction &CGF,
1049 EHCatchScope &catchScope) {
1050 if (EHPersonality::get(CGF).isWasmPersonality())
1051 return emitWasmCatchPadBlock(CGF, catchScope);
1052 if (EHPersonality::get(CGF).usesFuncletPads())
1053 return emitCatchPadBlock(CGF, catchScope);
1055 llvm::BasicBlock *dispatchBlock = catchScope.getCachedEHDispatchBlock();
1056 assert(dispatchBlock);
1058 // If there's only a single catch-all, getEHDispatchBlock returned
1059 // that catch-all as the dispatch block.
1060 if (catchScope.getNumHandlers() == 1 &&
1061 catchScope.getHandler(0).isCatchAll()) {
1062 assert(dispatchBlock == catchScope.getHandler(0).Block);
1066 CGBuilderTy::InsertPoint savedIP = CGF.Builder.saveIP();
1067 CGF.EmitBlockAfterUses(dispatchBlock);
1069 // Select the right handler.
1070 llvm::Function *llvm_eh_typeid_for =
1071 CGF.CGM.getIntrinsic(llvm::Intrinsic::eh_typeid_for);
1073 // Load the selector value.
1074 llvm::Value *selector = CGF.getSelectorFromSlot();
1076 // Test against each of the exception types we claim to catch.
1077 for (unsigned i = 0, e = catchScope.getNumHandlers(); ; ++i) {
1078 assert(i < e && "ran off end of handlers!");
1079 const EHCatchScope::Handler &handler = catchScope.getHandler(i);
1081 llvm::Value *typeValue = handler.Type.RTTI;
1082 assert(handler.Type.Flags == 0 &&
1083 "landingpads do not support catch handler flags");
1084 assert(typeValue && "fell into catch-all case!");
1085 typeValue = CGF.Builder.CreateBitCast(typeValue, CGF.Int8PtrTy);
1087 // Figure out the next block.
1089 llvm::BasicBlock *nextBlock;
1091 // If this is the last handler, we're at the end, and the next
1092 // block is the block for the enclosing EH scope.
1094 nextBlock = CGF.getEHDispatchBlock(catchScope.getEnclosingEHScope());
1097 // If the next handler is a catch-all, we're at the end, and the
1098 // next block is that handler.
1099 } else if (catchScope.getHandler(i+1).isCatchAll()) {
1100 nextBlock = catchScope.getHandler(i+1).Block;
1103 // Otherwise, we're not at the end and we need a new block.
1105 nextBlock = CGF.createBasicBlock("catch.fallthrough");
1109 // Figure out the catch type's index in the LSDA's type table.
1110 llvm::CallInst *typeIndex =
1111 CGF.Builder.CreateCall(llvm_eh_typeid_for, typeValue);
1112 typeIndex->setDoesNotThrow();
1114 llvm::Value *matchesTypeIndex =
1115 CGF.Builder.CreateICmpEQ(selector, typeIndex, "matches");
1116 CGF.Builder.CreateCondBr(matchesTypeIndex, handler.Block, nextBlock);
1118 // If the next handler is a catch-all, we're completely done.
1120 CGF.Builder.restoreIP(savedIP);
1123 // Otherwise we need to emit and continue at that block.
1124 CGF.EmitBlock(nextBlock);
1128 void CodeGenFunction::popCatchScope() {
1129 EHCatchScope &catchScope = cast<EHCatchScope>(*EHStack.begin());
1130 if (catchScope.hasEHBranches())
1131 emitCatchDispatchBlock(*this, catchScope);
1135 void CodeGenFunction::ExitCXXTryStmt(const CXXTryStmt &S, bool IsFnTryBlock) {
1136 unsigned NumHandlers = S.getNumHandlers();
1137 EHCatchScope &CatchScope = cast<EHCatchScope>(*EHStack.begin());
1138 assert(CatchScope.getNumHandlers() == NumHandlers);
1139 llvm::BasicBlock *DispatchBlock = CatchScope.getCachedEHDispatchBlock();
1141 // If the catch was not required, bail out now.
1142 if (!CatchScope.hasEHBranches()) {
1143 CatchScope.clearHandlerBlocks();
1148 // Emit the structure of the EH dispatch for this catch.
1149 emitCatchDispatchBlock(*this, CatchScope);
1151 // Copy the handler blocks off before we pop the EH stack. Emitting
1152 // the handlers might scribble on this memory.
1153 SmallVector<EHCatchScope::Handler, 8> Handlers(
1154 CatchScope.begin(), CatchScope.begin() + NumHandlers);
1158 // The fall-through block.
1159 llvm::BasicBlock *ContBB = createBasicBlock("try.cont");
1161 // We just emitted the body of the try; jump to the continue block.
1162 if (HaveInsertPoint())
1163 Builder.CreateBr(ContBB);
1165 // Determine if we need an implicit rethrow for all these catch handlers;
1166 // see the comment below.
1167 bool doImplicitRethrow = false;
1169 doImplicitRethrow = isa<CXXDestructorDecl>(CurCodeDecl) ||
1170 isa<CXXConstructorDecl>(CurCodeDecl);
1172 // Wasm uses Windows-style EH instructions, but merges all catch clauses into
1173 // one big catchpad. So we save the old funclet pad here before we traverse
1174 // each catch handler.
1175 SaveAndRestore<llvm::Instruction *> RestoreCurrentFuncletPad(
1177 llvm::BasicBlock *WasmCatchStartBlock = nullptr;
1178 if (EHPersonality::get(*this).isWasmPersonality()) {
1180 cast<llvm::CatchSwitchInst>(DispatchBlock->getFirstNonPHI());
1181 WasmCatchStartBlock = CatchSwitch->hasUnwindDest()
1182 ? CatchSwitch->getSuccessor(1)
1183 : CatchSwitch->getSuccessor(0);
1184 auto *CPI = cast<llvm::CatchPadInst>(WasmCatchStartBlock->getFirstNonPHI());
1185 CurrentFuncletPad = CPI;
1188 // Perversely, we emit the handlers backwards precisely because we
1189 // want them to appear in source order. In all of these cases, the
1190 // catch block will have exactly one predecessor, which will be a
1191 // particular block in the catch dispatch. However, in the case of
1192 // a catch-all, one of the dispatch blocks will branch to two
1193 // different handlers, and EmitBlockAfterUses will cause the second
1194 // handler to be moved before the first.
1195 bool HasCatchAll = false;
1196 for (unsigned I = NumHandlers; I != 0; --I) {
1197 HasCatchAll |= Handlers[I - 1].isCatchAll();
1198 llvm::BasicBlock *CatchBlock = Handlers[I-1].Block;
1199 EmitBlockAfterUses(CatchBlock);
1201 // Catch the exception if this isn't a catch-all.
1202 const CXXCatchStmt *C = S.getHandler(I-1);
1204 // Enter a cleanup scope, including the catch variable and the
1206 RunCleanupsScope CatchScope(*this);
1208 // Initialize the catch variable and set up the cleanups.
1209 SaveAndRestore<llvm::Instruction *> RestoreCurrentFuncletPad(
1211 CGM.getCXXABI().emitBeginCatch(*this, C);
1213 // Emit the PGO counter increment.
1214 incrementProfileCounter(C);
1216 // Perform the body of the catch.
1217 EmitStmt(C->getHandlerBlock());
1219 // [except.handle]p11:
1220 // The currently handled exception is rethrown if control
1221 // reaches the end of a handler of the function-try-block of a
1222 // constructor or destructor.
1224 // It is important that we only do this on fallthrough and not on
1225 // return. Note that it's illegal to put a return in a
1226 // constructor function-try-block's catch handler (p14), so this
1227 // really only applies to destructors.
1228 if (doImplicitRethrow && HaveInsertPoint()) {
1229 CGM.getCXXABI().emitRethrow(*this, /*isNoReturn*/false);
1230 Builder.CreateUnreachable();
1231 Builder.ClearInsertionPoint();
1234 // Fall out through the catch cleanups.
1235 CatchScope.ForceCleanup();
1237 // Branch out of the try.
1238 if (HaveInsertPoint())
1239 Builder.CreateBr(ContBB);
1242 // Because in wasm we merge all catch clauses into one big catchpad, in case
1243 // none of the types in catch handlers matches after we test against each of
1244 // them, we should unwind to the next EH enclosing scope. We generate a call
1245 // to rethrow function here to do that.
1246 if (EHPersonality::get(*this).isWasmPersonality() && !HasCatchAll) {
1247 assert(WasmCatchStartBlock);
1248 // Navigate for the "rethrow" block we created in emitWasmCatchPadBlock().
1249 // Wasm uses landingpad-style conditional branches to compare selectors, so
1250 // we follow the false destination for each of the cond branches to reach
1251 // the rethrow block.
1252 llvm::BasicBlock *RethrowBlock = WasmCatchStartBlock;
1253 while (llvm::Instruction *TI = RethrowBlock->getTerminator()) {
1254 auto *BI = cast<llvm::BranchInst>(TI);
1255 assert(BI->isConditional());
1256 RethrowBlock = BI->getSuccessor(1);
1258 assert(RethrowBlock != WasmCatchStartBlock && RethrowBlock->empty());
1259 Builder.SetInsertPoint(RethrowBlock);
1260 llvm::Function *RethrowInCatchFn =
1261 CGM.getIntrinsic(llvm::Intrinsic::wasm_rethrow_in_catch);
1262 EmitNoreturnRuntimeCallOrInvoke(RethrowInCatchFn, {});
1266 incrementProfileCounter(&S);
1270 struct CallEndCatchForFinally final : EHScopeStack::Cleanup {
1271 llvm::Value *ForEHVar;
1272 llvm::FunctionCallee EndCatchFn;
1273 CallEndCatchForFinally(llvm::Value *ForEHVar,
1274 llvm::FunctionCallee EndCatchFn)
1275 : ForEHVar(ForEHVar), EndCatchFn(EndCatchFn) {}
1277 void Emit(CodeGenFunction &CGF, Flags flags) override {
1278 llvm::BasicBlock *EndCatchBB = CGF.createBasicBlock("finally.endcatch");
1279 llvm::BasicBlock *CleanupContBB =
1280 CGF.createBasicBlock("finally.cleanup.cont");
1282 llvm::Value *ShouldEndCatch =
1283 CGF.Builder.CreateFlagLoad(ForEHVar, "finally.endcatch");
1284 CGF.Builder.CreateCondBr(ShouldEndCatch, EndCatchBB, CleanupContBB);
1285 CGF.EmitBlock(EndCatchBB);
1286 CGF.EmitRuntimeCallOrInvoke(EndCatchFn); // catch-all, so might throw
1287 CGF.EmitBlock(CleanupContBB);
1291 struct PerformFinally final : EHScopeStack::Cleanup {
1293 llvm::Value *ForEHVar;
1294 llvm::FunctionCallee EndCatchFn;
1295 llvm::FunctionCallee RethrowFn;
1296 llvm::Value *SavedExnVar;
1298 PerformFinally(const Stmt *Body, llvm::Value *ForEHVar,
1299 llvm::FunctionCallee EndCatchFn,
1300 llvm::FunctionCallee RethrowFn, llvm::Value *SavedExnVar)
1301 : Body(Body), ForEHVar(ForEHVar), EndCatchFn(EndCatchFn),
1302 RethrowFn(RethrowFn), SavedExnVar(SavedExnVar) {}
1304 void Emit(CodeGenFunction &CGF, Flags flags) override {
1305 // Enter a cleanup to call the end-catch function if one was provided.
1307 CGF.EHStack.pushCleanup<CallEndCatchForFinally>(NormalAndEHCleanup,
1308 ForEHVar, EndCatchFn);
1310 // Save the current cleanup destination in case there are
1311 // cleanups in the finally block.
1312 llvm::Value *SavedCleanupDest =
1313 CGF.Builder.CreateLoad(CGF.getNormalCleanupDestSlot(),
1314 "cleanup.dest.saved");
1316 // Emit the finally block.
1319 // If the end of the finally is reachable, check whether this was
1320 // for EH. If so, rethrow.
1321 if (CGF.HaveInsertPoint()) {
1322 llvm::BasicBlock *RethrowBB = CGF.createBasicBlock("finally.rethrow");
1323 llvm::BasicBlock *ContBB = CGF.createBasicBlock("finally.cont");
1325 llvm::Value *ShouldRethrow =
1326 CGF.Builder.CreateFlagLoad(ForEHVar, "finally.shouldthrow");
1327 CGF.Builder.CreateCondBr(ShouldRethrow, RethrowBB, ContBB);
1329 CGF.EmitBlock(RethrowBB);
1331 CGF.EmitRuntimeCallOrInvoke(RethrowFn,
1332 CGF.Builder.CreateAlignedLoad(SavedExnVar, CGF.getPointerAlign()));
1334 CGF.EmitRuntimeCallOrInvoke(RethrowFn);
1336 CGF.Builder.CreateUnreachable();
1338 CGF.EmitBlock(ContBB);
1340 // Restore the cleanup destination.
1341 CGF.Builder.CreateStore(SavedCleanupDest,
1342 CGF.getNormalCleanupDestSlot());
1345 // Leave the end-catch cleanup. As an optimization, pretend that
1346 // the fallthrough path was inaccessible; we've dynamically proven
1347 // that we're not in the EH case along that path.
1349 CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveAndClearIP();
1350 CGF.PopCleanupBlock();
1351 CGF.Builder.restoreIP(SavedIP);
1354 // Now make sure we actually have an insertion point or the
1355 // cleanup gods will hate us.
1356 CGF.EnsureInsertPoint();
1359 } // end anonymous namespace
1361 /// Enters a finally block for an implementation using zero-cost
1362 /// exceptions. This is mostly general, but hard-codes some
1363 /// language/ABI-specific behavior in the catch-all sections.
1364 void CodeGenFunction::FinallyInfo::enter(CodeGenFunction &CGF, const Stmt *body,
1365 llvm::FunctionCallee beginCatchFn,
1366 llvm::FunctionCallee endCatchFn,
1367 llvm::FunctionCallee rethrowFn) {
1368 assert((!!beginCatchFn) == (!!endCatchFn) &&
1369 "begin/end catch functions not paired");
1370 assert(rethrowFn && "rethrow function is required");
1372 BeginCatchFn = beginCatchFn;
1374 // The rethrow function has one of the following two types:
1377 // In the latter case we need to pass it the exception object.
1378 // But we can't use the exception slot because the @finally might
1379 // have a landing pad (which would overwrite the exception slot).
1380 llvm::FunctionType *rethrowFnTy = rethrowFn.getFunctionType();
1381 SavedExnVar = nullptr;
1382 if (rethrowFnTy->getNumParams())
1383 SavedExnVar = CGF.CreateTempAlloca(CGF.Int8PtrTy, "finally.exn");
1385 // A finally block is a statement which must be executed on any edge
1386 // out of a given scope. Unlike a cleanup, the finally block may
1387 // contain arbitrary control flow leading out of itself. In
1388 // addition, finally blocks should always be executed, even if there
1389 // are no catch handlers higher on the stack. Therefore, we
1390 // surround the protected scope with a combination of a normal
1391 // cleanup (to catch attempts to break out of the block via normal
1392 // control flow) and an EH catch-all (semantically "outside" any try
1393 // statement to which the finally block might have been attached).
1394 // The finally block itself is generated in the context of a cleanup
1395 // which conditionally leaves the catch-all.
1397 // Jump destination for performing the finally block on an exception
1398 // edge. We'll never actually reach this block, so unreachable is
1400 RethrowDest = CGF.getJumpDestInCurrentScope(CGF.getUnreachableBlock());
1402 // Whether the finally block is being executed for EH purposes.
1403 ForEHVar = CGF.CreateTempAlloca(CGF.Builder.getInt1Ty(), "finally.for-eh");
1404 CGF.Builder.CreateFlagStore(false, ForEHVar);
1406 // Enter a normal cleanup which will perform the @finally block.
1407 CGF.EHStack.pushCleanup<PerformFinally>(NormalCleanup, body,
1408 ForEHVar, endCatchFn,
1409 rethrowFn, SavedExnVar);
1411 // Enter a catch-all scope.
1412 llvm::BasicBlock *catchBB = CGF.createBasicBlock("finally.catchall");
1413 EHCatchScope *catchScope = CGF.EHStack.pushCatch(1);
1414 catchScope->setCatchAllHandler(0, catchBB);
1417 void CodeGenFunction::FinallyInfo::exit(CodeGenFunction &CGF) {
1418 // Leave the finally catch-all.
1419 EHCatchScope &catchScope = cast<EHCatchScope>(*CGF.EHStack.begin());
1420 llvm::BasicBlock *catchBB = catchScope.getHandler(0).Block;
1422 CGF.popCatchScope();
1424 // If there are any references to the catch-all block, emit it.
1425 if (catchBB->use_empty()) {
1428 CGBuilderTy::InsertPoint savedIP = CGF.Builder.saveAndClearIP();
1429 CGF.EmitBlock(catchBB);
1431 llvm::Value *exn = nullptr;
1433 // If there's a begin-catch function, call it.
1435 exn = CGF.getExceptionFromSlot();
1436 CGF.EmitNounwindRuntimeCall(BeginCatchFn, exn);
1439 // If we need to remember the exception pointer to rethrow later, do so.
1441 if (!exn) exn = CGF.getExceptionFromSlot();
1442 CGF.Builder.CreateAlignedStore(exn, SavedExnVar, CGF.getPointerAlign());
1445 // Tell the cleanups in the finally block that we're do this for EH.
1446 CGF.Builder.CreateFlagStore(true, ForEHVar);
1448 // Thread a jump through the finally cleanup.
1449 CGF.EmitBranchThroughCleanup(RethrowDest);
1451 CGF.Builder.restoreIP(savedIP);
1454 // Finally, leave the @finally cleanup.
1455 CGF.PopCleanupBlock();
1458 llvm::BasicBlock *CodeGenFunction::getTerminateLandingPad() {
1459 if (TerminateLandingPad)
1460 return TerminateLandingPad;
1462 CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
1464 // This will get inserted at the end of the function.
1465 TerminateLandingPad = createBasicBlock("terminate.lpad");
1466 Builder.SetInsertPoint(TerminateLandingPad);
1468 // Tell the backend that this is a landing pad.
1469 const EHPersonality &Personality = EHPersonality::get(*this);
1471 if (!CurFn->hasPersonalityFn())
1472 CurFn->setPersonalityFn(getOpaquePersonalityFn(CGM, Personality));
1474 llvm::LandingPadInst *LPadInst =
1475 Builder.CreateLandingPad(llvm::StructType::get(Int8PtrTy, Int32Ty), 0);
1476 LPadInst->addClause(getCatchAllValue(*this));
1478 llvm::Value *Exn = nullptr;
1479 if (getLangOpts().CPlusPlus)
1480 Exn = Builder.CreateExtractValue(LPadInst, 0);
1481 llvm::CallInst *terminateCall =
1482 CGM.getCXXABI().emitTerminateForUnexpectedException(*this, Exn);
1483 terminateCall->setDoesNotReturn();
1484 Builder.CreateUnreachable();
1486 // Restore the saved insertion state.
1487 Builder.restoreIP(SavedIP);
1489 return TerminateLandingPad;
1492 llvm::BasicBlock *CodeGenFunction::getTerminateHandler() {
1493 if (TerminateHandler)
1494 return TerminateHandler;
1496 // Set up the terminate handler. This block is inserted at the very
1497 // end of the function by FinishFunction.
1498 TerminateHandler = createBasicBlock("terminate.handler");
1499 CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
1500 Builder.SetInsertPoint(TerminateHandler);
1502 llvm::Value *Exn = nullptr;
1503 if (getLangOpts().CPlusPlus)
1504 Exn = getExceptionFromSlot();
1505 llvm::CallInst *terminateCall =
1506 CGM.getCXXABI().emitTerminateForUnexpectedException(*this, Exn);
1507 terminateCall->setDoesNotReturn();
1508 Builder.CreateUnreachable();
1510 // Restore the saved insertion state.
1511 Builder.restoreIP(SavedIP);
1513 return TerminateHandler;
1516 llvm::BasicBlock *CodeGenFunction::getTerminateFunclet() {
1517 assert(EHPersonality::get(*this).usesFuncletPads() &&
1518 "use getTerminateLandingPad for non-funclet EH");
1520 llvm::BasicBlock *&TerminateFunclet = TerminateFunclets[CurrentFuncletPad];
1521 if (TerminateFunclet)
1522 return TerminateFunclet;
1524 CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
1526 // Set up the terminate handler. This block is inserted at the very
1527 // end of the function by FinishFunction.
1528 TerminateFunclet = createBasicBlock("terminate.handler");
1529 Builder.SetInsertPoint(TerminateFunclet);
1531 // Create the cleanuppad using the current parent pad as its token. Use 'none'
1532 // if this is a top-level terminate scope, which is the common case.
1533 SaveAndRestore<llvm::Instruction *> RestoreCurrentFuncletPad(
1535 llvm::Value *ParentPad = CurrentFuncletPad;
1537 ParentPad = llvm::ConstantTokenNone::get(CGM.getLLVMContext());
1538 CurrentFuncletPad = Builder.CreateCleanupPad(ParentPad);
1540 // Emit the __std_terminate call.
1541 llvm::Value *Exn = nullptr;
1542 // In case of wasm personality, we need to pass the exception value to
1543 // __clang_call_terminate function.
1544 if (getLangOpts().CPlusPlus &&
1545 EHPersonality::get(*this).isWasmPersonality()) {
1546 llvm::Function *GetExnFn =
1547 CGM.getIntrinsic(llvm::Intrinsic::wasm_get_exception);
1548 Exn = Builder.CreateCall(GetExnFn, CurrentFuncletPad);
1550 llvm::CallInst *terminateCall =
1551 CGM.getCXXABI().emitTerminateForUnexpectedException(*this, Exn);
1552 terminateCall->setDoesNotReturn();
1553 Builder.CreateUnreachable();
1555 // Restore the saved insertion state.
1556 Builder.restoreIP(SavedIP);
1558 return TerminateFunclet;
1561 llvm::BasicBlock *CodeGenFunction::getEHResumeBlock(bool isCleanup) {
1562 if (EHResumeBlock) return EHResumeBlock;
1564 CGBuilderTy::InsertPoint SavedIP = Builder.saveIP();
1566 // We emit a jump to a notional label at the outermost unwind state.
1567 EHResumeBlock = createBasicBlock("eh.resume");
1568 Builder.SetInsertPoint(EHResumeBlock);
1570 const EHPersonality &Personality = EHPersonality::get(*this);
1572 // This can always be a call because we necessarily didn't find
1573 // anything on the EH stack which needs our help.
1574 const char *RethrowName = Personality.CatchallRethrowFn;
1575 if (RethrowName != nullptr && !isCleanup) {
1576 EmitRuntimeCall(getCatchallRethrowFn(CGM, RethrowName),
1577 getExceptionFromSlot())->setDoesNotReturn();
1578 Builder.CreateUnreachable();
1579 Builder.restoreIP(SavedIP);
1580 return EHResumeBlock;
1583 // Recreate the landingpad's return value for the 'resume' instruction.
1584 llvm::Value *Exn = getExceptionFromSlot();
1585 llvm::Value *Sel = getSelectorFromSlot();
1587 llvm::Type *LPadType = llvm::StructType::get(Exn->getType(), Sel->getType());
1588 llvm::Value *LPadVal = llvm::UndefValue::get(LPadType);
1589 LPadVal = Builder.CreateInsertValue(LPadVal, Exn, 0, "lpad.val");
1590 LPadVal = Builder.CreateInsertValue(LPadVal, Sel, 1, "lpad.val");
1592 Builder.CreateResume(LPadVal);
1593 Builder.restoreIP(SavedIP);
1594 return EHResumeBlock;
1597 void CodeGenFunction::EmitSEHTryStmt(const SEHTryStmt &S) {
1600 JumpDest TryExit = getJumpDestInCurrentScope("__try.__leave");
1602 SEHTryEpilogueStack.push_back(&TryExit);
1603 EmitStmt(S.getTryBlock());
1604 SEHTryEpilogueStack.pop_back();
1606 if (!TryExit.getBlock()->use_empty())
1607 EmitBlock(TryExit.getBlock(), /*IsFinished=*/true);
1609 delete TryExit.getBlock();
1615 struct PerformSEHFinally final : EHScopeStack::Cleanup {
1616 llvm::Function *OutlinedFinally;
1617 PerformSEHFinally(llvm::Function *OutlinedFinally)
1618 : OutlinedFinally(OutlinedFinally) {}
1620 void Emit(CodeGenFunction &CGF, Flags F) override {
1621 ASTContext &Context = CGF.getContext();
1622 CodeGenModule &CGM = CGF.CGM;
1626 // Compute the two argument values.
1627 QualType ArgTys[2] = {Context.UnsignedCharTy, Context.VoidPtrTy};
1628 llvm::Value *FP = nullptr;
1629 // If CFG.IsOutlinedSEHHelper is true, then we are within a finally block.
1630 if (CGF.IsOutlinedSEHHelper) {
1631 FP = &CGF.CurFn->arg_begin()[1];
1633 llvm::Function *LocalAddrFn =
1634 CGM.getIntrinsic(llvm::Intrinsic::localaddress);
1635 FP = CGF.Builder.CreateCall(LocalAddrFn);
1638 llvm::Value *IsForEH =
1639 llvm::ConstantInt::get(CGF.ConvertType(ArgTys[0]), F.isForEHCleanup());
1640 Args.add(RValue::get(IsForEH), ArgTys[0]);
1641 Args.add(RValue::get(FP), ArgTys[1]);
1643 // Arrange a two-arg function info and type.
1644 const CGFunctionInfo &FnInfo =
1645 CGM.getTypes().arrangeBuiltinFunctionCall(Context.VoidTy, Args);
1647 auto Callee = CGCallee::forDirect(OutlinedFinally);
1648 CGF.EmitCall(FnInfo, Callee, ReturnValueSlot(), Args);
1651 } // end anonymous namespace
1654 /// Find all local variable captures in the statement.
1655 struct CaptureFinder : ConstStmtVisitor<CaptureFinder> {
1656 CodeGenFunction &ParentCGF;
1657 const VarDecl *ParentThis;
1658 llvm::SmallSetVector<const VarDecl *, 4> Captures;
1659 Address SEHCodeSlot = Address::invalid();
1660 CaptureFinder(CodeGenFunction &ParentCGF, const VarDecl *ParentThis)
1661 : ParentCGF(ParentCGF), ParentThis(ParentThis) {}
1663 // Return true if we need to do any capturing work.
1664 bool foundCaptures() {
1665 return !Captures.empty() || SEHCodeSlot.isValid();
1668 void Visit(const Stmt *S) {
1669 // See if this is a capture, then recurse.
1670 ConstStmtVisitor<CaptureFinder>::Visit(S);
1671 for (const Stmt *Child : S->children())
1676 void VisitDeclRefExpr(const DeclRefExpr *E) {
1677 // If this is already a capture, just make sure we capture 'this'.
1678 if (E->refersToEnclosingVariableOrCapture()) {
1679 Captures.insert(ParentThis);
1683 const auto *D = dyn_cast<VarDecl>(E->getDecl());
1684 if (D && D->isLocalVarDeclOrParm() && D->hasLocalStorage())
1688 void VisitCXXThisExpr(const CXXThisExpr *E) {
1689 Captures.insert(ParentThis);
1692 void VisitCallExpr(const CallExpr *E) {
1693 // We only need to add parent frame allocations for these builtins in x86.
1694 if (ParentCGF.getTarget().getTriple().getArch() != llvm::Triple::x86)
1697 unsigned ID = E->getBuiltinCallee();
1699 case Builtin::BI__exception_code:
1700 case Builtin::BI_exception_code:
1701 // This is the simple case where we are the outermost finally. All we
1702 // have to do here is make sure we escape this and recover it in the
1703 // outlined handler.
1704 if (!SEHCodeSlot.isValid())
1705 SEHCodeSlot = ParentCGF.SEHCodeSlotStack.back();
1710 } // end anonymous namespace
1712 Address CodeGenFunction::recoverAddrOfEscapedLocal(CodeGenFunction &ParentCGF,
1714 llvm::Value *ParentFP) {
1715 llvm::CallInst *RecoverCall = nullptr;
1716 CGBuilderTy Builder(*this, AllocaInsertPt);
1717 if (auto *ParentAlloca = dyn_cast<llvm::AllocaInst>(ParentVar.getPointer())) {
1718 // Mark the variable escaped if nobody else referenced it and compute the
1719 // localescape index.
1720 auto InsertPair = ParentCGF.EscapedLocals.insert(
1721 std::make_pair(ParentAlloca, ParentCGF.EscapedLocals.size()));
1722 int FrameEscapeIdx = InsertPair.first->second;
1723 // call i8* @llvm.localrecover(i8* bitcast(@parentFn), i8* %fp, i32 N)
1724 llvm::Function *FrameRecoverFn = llvm::Intrinsic::getDeclaration(
1725 &CGM.getModule(), llvm::Intrinsic::localrecover);
1726 llvm::Constant *ParentI8Fn =
1727 llvm::ConstantExpr::getBitCast(ParentCGF.CurFn, Int8PtrTy);
1728 RecoverCall = Builder.CreateCall(
1729 FrameRecoverFn, {ParentI8Fn, ParentFP,
1730 llvm::ConstantInt::get(Int32Ty, FrameEscapeIdx)});
1733 // If the parent didn't have an alloca, we're doing some nested outlining.
1734 // Just clone the existing localrecover call, but tweak the FP argument to
1735 // use our FP value. All other arguments are constants.
1736 auto *ParentRecover =
1737 cast<llvm::IntrinsicInst>(ParentVar.getPointer()->stripPointerCasts());
1738 assert(ParentRecover->getIntrinsicID() == llvm::Intrinsic::localrecover &&
1739 "expected alloca or localrecover in parent LocalDeclMap");
1740 RecoverCall = cast<llvm::CallInst>(ParentRecover->clone());
1741 RecoverCall->setArgOperand(1, ParentFP);
1742 RecoverCall->insertBefore(AllocaInsertPt);
1745 // Bitcast the variable, rename it, and insert it in the local decl map.
1746 llvm::Value *ChildVar =
1747 Builder.CreateBitCast(RecoverCall, ParentVar.getType());
1748 ChildVar->setName(ParentVar.getName());
1749 return Address(ChildVar, ParentVar.getAlignment());
1752 void CodeGenFunction::EmitCapturedLocals(CodeGenFunction &ParentCGF,
1753 const Stmt *OutlinedStmt,
1755 // Find all captures in the Stmt.
1756 CaptureFinder Finder(ParentCGF, ParentCGF.CXXABIThisDecl);
1757 Finder.Visit(OutlinedStmt);
1759 // We can exit early on x86_64 when there are no captures. We just have to
1760 // save the exception code in filters so that __exception_code() works.
1761 if (!Finder.foundCaptures() &&
1762 CGM.getTarget().getTriple().getArch() != llvm::Triple::x86) {
1764 EmitSEHExceptionCodeSave(ParentCGF, nullptr, nullptr);
1768 llvm::Value *EntryFP = nullptr;
1769 CGBuilderTy Builder(CGM, AllocaInsertPt);
1770 if (IsFilter && CGM.getTarget().getTriple().getArch() == llvm::Triple::x86) {
1771 // 32-bit SEH filters need to be careful about FP recovery. The end of the
1772 // EH registration is passed in as the EBP physical register. We can
1773 // recover that with llvm.frameaddress(1).
1774 EntryFP = Builder.CreateCall(
1775 CGM.getIntrinsic(llvm::Intrinsic::frameaddress, AllocaInt8PtrTy),
1776 {Builder.getInt32(1)});
1778 // Otherwise, for x64 and 32-bit finally functions, the parent FP is the
1779 // second parameter.
1780 auto AI = CurFn->arg_begin();
1785 llvm::Value *ParentFP = EntryFP;
1787 // Given whatever FP the runtime provided us in EntryFP, recover the true
1788 // frame pointer of the parent function. We only need to do this in filters,
1789 // since finally funclets recover the parent FP for us.
1790 llvm::Function *RecoverFPIntrin =
1791 CGM.getIntrinsic(llvm::Intrinsic::eh_recoverfp);
1792 llvm::Constant *ParentI8Fn =
1793 llvm::ConstantExpr::getBitCast(ParentCGF.CurFn, Int8PtrTy);
1794 ParentFP = Builder.CreateCall(RecoverFPIntrin, {ParentI8Fn, EntryFP});
1797 // Create llvm.localrecover calls for all captures.
1798 for (const VarDecl *VD : Finder.Captures) {
1799 if (isa<ImplicitParamDecl>(VD)) {
1800 CGM.ErrorUnsupported(VD, "'this' captured by SEH");
1801 CXXThisValue = llvm::UndefValue::get(ConvertTypeForMem(VD->getType()));
1804 if (VD->getType()->isVariablyModifiedType()) {
1805 CGM.ErrorUnsupported(VD, "VLA captured by SEH");
1808 assert((isa<ImplicitParamDecl>(VD) || VD->isLocalVarDeclOrParm()) &&
1809 "captured non-local variable");
1811 // If this decl hasn't been declared yet, it will be declared in the
1813 auto I = ParentCGF.LocalDeclMap.find(VD);
1814 if (I == ParentCGF.LocalDeclMap.end())
1817 Address ParentVar = I->second;
1819 VD, recoverAddrOfEscapedLocal(ParentCGF, ParentVar, ParentFP));
1822 if (Finder.SEHCodeSlot.isValid()) {
1823 SEHCodeSlotStack.push_back(
1824 recoverAddrOfEscapedLocal(ParentCGF, Finder.SEHCodeSlot, ParentFP));
1828 EmitSEHExceptionCodeSave(ParentCGF, ParentFP, EntryFP);
1831 /// Arrange a function prototype that can be called by Windows exception
1832 /// handling personalities. On Win64, the prototype looks like:
1833 /// RetTy func(void *EHPtrs, void *ParentFP);
1834 void CodeGenFunction::startOutlinedSEHHelper(CodeGenFunction &ParentCGF,
1836 const Stmt *OutlinedStmt) {
1837 SourceLocation StartLoc = OutlinedStmt->getBeginLoc();
1839 // Get the mangled function name.
1840 SmallString<128> Name;
1842 llvm::raw_svector_ostream OS(Name);
1843 const NamedDecl *ParentSEHFn = ParentCGF.CurSEHParent;
1844 assert(ParentSEHFn && "No CurSEHParent!");
1845 MangleContext &Mangler = CGM.getCXXABI().getMangleContext();
1847 Mangler.mangleSEHFilterExpression(ParentSEHFn, OS);
1849 Mangler.mangleSEHFinallyBlock(ParentSEHFn, OS);
1852 FunctionArgList Args;
1853 if (CGM.getTarget().getTriple().getArch() != llvm::Triple::x86 || !IsFilter) {
1854 // All SEH finally functions take two parameters. Win64 filters take two
1855 // parameters. Win32 filters take no parameters.
1857 Args.push_back(ImplicitParamDecl::Create(
1858 getContext(), /*DC=*/nullptr, StartLoc,
1859 &getContext().Idents.get("exception_pointers"),
1860 getContext().VoidPtrTy, ImplicitParamDecl::Other));
1862 Args.push_back(ImplicitParamDecl::Create(
1863 getContext(), /*DC=*/nullptr, StartLoc,
1864 &getContext().Idents.get("abnormal_termination"),
1865 getContext().UnsignedCharTy, ImplicitParamDecl::Other));
1867 Args.push_back(ImplicitParamDecl::Create(
1868 getContext(), /*DC=*/nullptr, StartLoc,
1869 &getContext().Idents.get("frame_pointer"), getContext().VoidPtrTy,
1870 ImplicitParamDecl::Other));
1873 QualType RetTy = IsFilter ? getContext().LongTy : getContext().VoidTy;
1875 const CGFunctionInfo &FnInfo =
1876 CGM.getTypes().arrangeBuiltinFunctionDeclaration(RetTy, Args);
1878 llvm::FunctionType *FnTy = CGM.getTypes().GetFunctionType(FnInfo);
1879 llvm::Function *Fn = llvm::Function::Create(
1880 FnTy, llvm::GlobalValue::InternalLinkage, Name.str(), &CGM.getModule());
1882 IsOutlinedSEHHelper = true;
1884 StartFunction(GlobalDecl(), RetTy, Fn, FnInfo, Args,
1885 OutlinedStmt->getBeginLoc(), OutlinedStmt->getBeginLoc());
1886 CurSEHParent = ParentCGF.CurSEHParent;
1888 CGM.SetLLVMFunctionAttributes(GlobalDecl(), FnInfo, CurFn);
1889 EmitCapturedLocals(ParentCGF, OutlinedStmt, IsFilter);
1892 /// Create a stub filter function that will ultimately hold the code of the
1893 /// filter expression. The EH preparation passes in LLVM will outline the code
1894 /// from the main function body into this stub.
1896 CodeGenFunction::GenerateSEHFilterFunction(CodeGenFunction &ParentCGF,
1897 const SEHExceptStmt &Except) {
1898 const Expr *FilterExpr = Except.getFilterExpr();
1899 startOutlinedSEHHelper(ParentCGF, true, FilterExpr);
1901 // Emit the original filter expression, convert to i32, and return.
1902 llvm::Value *R = EmitScalarExpr(FilterExpr);
1903 R = Builder.CreateIntCast(R, ConvertType(getContext().LongTy),
1904 FilterExpr->getType()->isSignedIntegerType());
1905 Builder.CreateStore(R, ReturnValue);
1907 FinishFunction(FilterExpr->getEndLoc());
1913 CodeGenFunction::GenerateSEHFinallyFunction(CodeGenFunction &ParentCGF,
1914 const SEHFinallyStmt &Finally) {
1915 const Stmt *FinallyBlock = Finally.getBlock();
1916 startOutlinedSEHHelper(ParentCGF, false, FinallyBlock);
1918 // Emit the original filter expression, convert to i32, and return.
1919 EmitStmt(FinallyBlock);
1921 FinishFunction(FinallyBlock->getEndLoc());
1926 void CodeGenFunction::EmitSEHExceptionCodeSave(CodeGenFunction &ParentCGF,
1927 llvm::Value *ParentFP,
1928 llvm::Value *EntryFP) {
1929 // Get the pointer to the EXCEPTION_POINTERS struct. This is returned by the
1930 // __exception_info intrinsic.
1931 if (CGM.getTarget().getTriple().getArch() != llvm::Triple::x86) {
1932 // On Win64, the info is passed as the first parameter to the filter.
1933 SEHInfo = &*CurFn->arg_begin();
1934 SEHCodeSlotStack.push_back(
1935 CreateMemTemp(getContext().IntTy, "__exception_code"));
1937 // On Win32, the EBP on entry to the filter points to the end of an
1938 // exception registration object. It contains 6 32-bit fields, and the info
1939 // pointer is stored in the second field. So, GEP 20 bytes backwards and
1940 // load the pointer.
1941 SEHInfo = Builder.CreateConstInBoundsGEP1_32(Int8Ty, EntryFP, -20);
1942 SEHInfo = Builder.CreateBitCast(SEHInfo, Int8PtrTy->getPointerTo());
1943 SEHInfo = Builder.CreateAlignedLoad(Int8PtrTy, SEHInfo, getPointerAlign());
1944 SEHCodeSlotStack.push_back(recoverAddrOfEscapedLocal(
1945 ParentCGF, ParentCGF.SEHCodeSlotStack.back(), ParentFP));
1948 // Save the exception code in the exception slot to unify exception access in
1949 // the filter function and the landing pad.
1950 // struct EXCEPTION_POINTERS {
1951 // EXCEPTION_RECORD *ExceptionRecord;
1952 // CONTEXT *ContextRecord;
1954 // int exceptioncode = exception_pointers->ExceptionRecord->ExceptionCode;
1955 llvm::Type *RecordTy = CGM.Int32Ty->getPointerTo();
1956 llvm::Type *PtrsTy = llvm::StructType::get(RecordTy, CGM.VoidPtrTy);
1957 llvm::Value *Ptrs = Builder.CreateBitCast(SEHInfo, PtrsTy->getPointerTo());
1958 llvm::Value *Rec = Builder.CreateStructGEP(PtrsTy, Ptrs, 0);
1959 Rec = Builder.CreateAlignedLoad(Rec, getPointerAlign());
1960 llvm::Value *Code = Builder.CreateAlignedLoad(Rec, getIntAlign());
1961 assert(!SEHCodeSlotStack.empty() && "emitting EH code outside of __except");
1962 Builder.CreateStore(Code, SEHCodeSlotStack.back());
1965 llvm::Value *CodeGenFunction::EmitSEHExceptionInfo() {
1966 // Sema should diagnose calling this builtin outside of a filter context, but
1967 // don't crash if we screw up.
1969 return llvm::UndefValue::get(Int8PtrTy);
1970 assert(SEHInfo->getType() == Int8PtrTy);
1974 llvm::Value *CodeGenFunction::EmitSEHExceptionCode() {
1975 assert(!SEHCodeSlotStack.empty() && "emitting EH code outside of __except");
1976 return Builder.CreateLoad(SEHCodeSlotStack.back());
1979 llvm::Value *CodeGenFunction::EmitSEHAbnormalTermination() {
1980 // Abnormal termination is just the first parameter to the outlined finally
1982 auto AI = CurFn->arg_begin();
1983 return Builder.CreateZExt(&*AI, Int32Ty);
1986 void CodeGenFunction::pushSEHCleanup(CleanupKind Kind,
1987 llvm::Function *FinallyFunc) {
1988 EHStack.pushCleanup<PerformSEHFinally>(Kind, FinallyFunc);
1991 void CodeGenFunction::EnterSEHTryStmt(const SEHTryStmt &S) {
1992 CodeGenFunction HelperCGF(CGM, /*suppressNewContext=*/true);
1993 if (const SEHFinallyStmt *Finally = S.getFinallyHandler()) {
1994 // Outline the finally block.
1995 llvm::Function *FinallyFunc =
1996 HelperCGF.GenerateSEHFinallyFunction(*this, *Finally);
1998 // Push a cleanup for __finally blocks.
1999 EHStack.pushCleanup<PerformSEHFinally>(NormalAndEHCleanup, FinallyFunc);
2003 // Otherwise, we must have an __except block.
2004 const SEHExceptStmt *Except = S.getExceptHandler();
2006 EHCatchScope *CatchScope = EHStack.pushCatch(1);
2007 SEHCodeSlotStack.push_back(
2008 CreateMemTemp(getContext().IntTy, "__exception_code"));
2010 // If the filter is known to evaluate to 1, then we can use the clause
2011 // "catch i8* null". We can't do this on x86 because the filter has to save
2012 // the exception code.
2014 ConstantEmitter(*this).tryEmitAbstract(Except->getFilterExpr(),
2015 getContext().IntTy);
2016 if (CGM.getTarget().getTriple().getArch() != llvm::Triple::x86 && C &&
2018 CatchScope->setCatchAllHandler(0, createBasicBlock("__except"));
2022 // In general, we have to emit an outlined filter function. Use the function
2023 // in place of the RTTI typeinfo global that C++ EH uses.
2024 llvm::Function *FilterFunc =
2025 HelperCGF.GenerateSEHFilterFunction(*this, *Except);
2026 llvm::Constant *OpaqueFunc =
2027 llvm::ConstantExpr::getBitCast(FilterFunc, Int8PtrTy);
2028 CatchScope->setHandler(0, OpaqueFunc, createBasicBlock("__except.ret"));
2031 void CodeGenFunction::ExitSEHTryStmt(const SEHTryStmt &S) {
2032 // Just pop the cleanup if it's a __finally block.
2033 if (S.getFinallyHandler()) {
2038 // Otherwise, we must have an __except block.
2039 const SEHExceptStmt *Except = S.getExceptHandler();
2040 assert(Except && "__try must have __finally xor __except");
2041 EHCatchScope &CatchScope = cast<EHCatchScope>(*EHStack.begin());
2043 // Don't emit the __except block if the __try block lacked invokes.
2044 // TODO: Model unwind edges from instructions, either with iload / istore or
2045 // a try body function.
2046 if (!CatchScope.hasEHBranches()) {
2047 CatchScope.clearHandlerBlocks();
2049 SEHCodeSlotStack.pop_back();
2053 // The fall-through block.
2054 llvm::BasicBlock *ContBB = createBasicBlock("__try.cont");
2056 // We just emitted the body of the __try; jump to the continue block.
2057 if (HaveInsertPoint())
2058 Builder.CreateBr(ContBB);
2060 // Check if our filter function returned true.
2061 emitCatchDispatchBlock(*this, CatchScope);
2063 // Grab the block before we pop the handler.
2064 llvm::BasicBlock *CatchPadBB = CatchScope.getHandler(0).Block;
2067 EmitBlockAfterUses(CatchPadBB);
2069 // __except blocks don't get outlined into funclets, so immediately do a
2071 llvm::CatchPadInst *CPI =
2072 cast<llvm::CatchPadInst>(CatchPadBB->getFirstNonPHI());
2073 llvm::BasicBlock *ExceptBB = createBasicBlock("__except");
2074 Builder.CreateCatchRet(CPI, ExceptBB);
2075 EmitBlock(ExceptBB);
2077 // On Win64, the exception code is returned in EAX. Copy it into the slot.
2078 if (CGM.getTarget().getTriple().getArch() != llvm::Triple::x86) {
2079 llvm::Function *SEHCodeIntrin =
2080 CGM.getIntrinsic(llvm::Intrinsic::eh_exceptioncode);
2081 llvm::Value *Code = Builder.CreateCall(SEHCodeIntrin, {CPI});
2082 Builder.CreateStore(Code, SEHCodeSlotStack.back());
2085 // Emit the __except body.
2086 EmitStmt(Except->getBlock());
2088 // End the lifetime of the exception code.
2089 SEHCodeSlotStack.pop_back();
2091 if (HaveInsertPoint())
2092 Builder.CreateBr(ContBB);
2097 void CodeGenFunction::EmitSEHLeaveStmt(const SEHLeaveStmt &S) {
2098 // If this code is reachable then emit a stop point (if generating
2099 // debug info). We have to do this ourselves because we are on the
2100 // "simple" statement path.
2101 if (HaveInsertPoint())
2104 // This must be a __leave from a __finally block, which we warn on and is UB.
2105 // Just emit unreachable.
2106 if (!isSEHTryScope()) {
2107 Builder.CreateUnreachable();
2108 Builder.ClearInsertionPoint();
2112 EmitBranchThroughCleanup(*SEHTryEpilogueStack.back());