1//===--- CGException.cpp - Emit LLVM Code for C++ exceptions ----*- C++ -*-===//
2//
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
6//
7//===----------------------------------------------------------------------===//
8//
9// This contains code dealing with C++ exception related code generation.
10//
11//===----------------------------------------------------------------------===//
12
13#include "CGCXXABI.h"
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"
29
30using namespace clang;
31using namespace CodeGen;
32
33static llvm::FunctionCallee getFreeExceptionFn(CodeGenModule &CGM) {
34 // void __cxa_free_exception(void *thrown_exception);
35
36 llvm::FunctionType *FTy =
37 llvm::FunctionType::get(CGM.VoidTy, CGM.Int8PtrTy, /*isVarArg=*/false);
38
39 return CGM.CreateRuntimeFunction(FTy, "__cxa_free_exception");
40}
41
42static llvm::FunctionCallee getUnexpectedFn(CodeGenModule &CGM) {
43 // void __cxa_call_unexpected(void *thrown_exception);
44
45 llvm::FunctionType *FTy =
46 llvm::FunctionType::get(CGM.VoidTy, CGM.Int8PtrTy, /*isVarArg=*/false);
47
48 return CGM.CreateRuntimeFunction(FTy, "__cxa_call_unexpected");
49}
50
51llvm::FunctionCallee CodeGenModule::getTerminateFn() {
52 // void __terminate();
53
54 llvm::FunctionType *FTy =
55 llvm::FunctionType::get(VoidTy, /*isVarArg=*/false);
56
57 StringRef name;
58
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";
67 else
68 name = "?terminate@@YAXXZ";
69 } else if (getLangOpts().ObjC &&
70 getLangOpts().ObjCRuntime.hasTerminate())
71 name = "objc_terminate";
72 else
73 name = "abort";
74 return CreateRuntimeFunction(FTy, name);
75}
76
77static llvm::FunctionCallee getCatchallRethrowFn(CodeGenModule &CGM,
78 StringRef Name) {
79 llvm::FunctionType *FTy =
80 llvm::FunctionType::get(CGM.VoidTy, CGM.Int8PtrTy, /*isVarArg=*/false);
81
82 return CGM.CreateRuntimeFunction(FTy, Name);
83}
84
85const EHPersonality EHPersonality::GNU_C = { "__gcc_personality_v0", nullptr };
86const EHPersonality
87EHPersonality::GNU_C_SJLJ = { "__gcc_personality_sj0", nullptr };
88const EHPersonality
89EHPersonality::GNU_C_SEH = { "__gcc_personality_seh0", nullptr };
90const EHPersonality
91EHPersonality::NeXT_ObjC = { "__objc_personality_v0", nullptr };
92const EHPersonality
93EHPersonality::GNU_CPlusPlus = { "__gxx_personality_v0", nullptr };
94const EHPersonality
95EHPersonality::GNU_CPlusPlus_SJLJ = { "__gxx_personality_sj0", nullptr };
96const EHPersonality
97EHPersonality::GNU_CPlusPlus_SEH = { "__gxx_personality_seh0", nullptr };
98const EHPersonality
99EHPersonality::GNU_ObjC = {"__gnu_objc_personality_v0", "objc_exception_throw"};
100const EHPersonality
101EHPersonality::GNU_ObjC_SJLJ = {"__gnu_objc_personality_sj0", "objc_exception_throw"};
102const EHPersonality
103EHPersonality::GNU_ObjC_SEH = {"__gnu_objc_personality_seh0", "objc_exception_throw"};
104const EHPersonality
105EHPersonality::GNU_ObjCXX = { "__gnustep_objcxx_personality_v0", nullptr };
106const EHPersonality
107EHPersonality::GNUstep_ObjC = { "__gnustep_objc_personality_v0", nullptr };
108const EHPersonality
109EHPersonality::MSVC_except_handler = { "_except_handler3", nullptr };
110const EHPersonality
111EHPersonality::MSVC_C_specific_handler = { "__C_specific_handler", nullptr };
112const EHPersonality
113EHPersonality::MSVC_CxxFrameHandler3 = { "__CxxFrameHandler3", nullptr };
114const EHPersonality
115EHPersonality::GNU_Wasm_CPlusPlus = { "__gxx_wasm_personality_v0", nullptr };
116const EHPersonality EHPersonality::XL_CPlusPlus = {"__xlcxx_personality_v1",
117 nullptr};
118
119static const EHPersonality &getCPersonality(const TargetInfo &Target,
120 const LangOptions &L) {
121 const llvm::Triple &T = Target.getTriple();
122 if (T.isWindowsMSVCEnvironment())
123 return EHPersonality::MSVC_CxxFrameHandler3;
124 if (L.hasSjLjExceptions())
125 return EHPersonality::GNU_C_SJLJ;
126 if (L.hasDWARFExceptions())
127 return EHPersonality::GNU_C;
128 if (L.hasSEHExceptions())
129 return EHPersonality::GNU_C_SEH;
130 return EHPersonality::GNU_C;
131}
132
133static const EHPersonality &getObjCPersonality(const TargetInfo &Target,
134 const LangOptions &L) {
135 const llvm::Triple &T = Target.getTriple();
136 if (T.isWindowsMSVCEnvironment())
137 return EHPersonality::MSVC_CxxFrameHandler3;
138
139 switch (L.ObjCRuntime.getKind()) {
140 case ObjCRuntime::FragileMacOSX:
141 return getCPersonality(Target, L);
142 case ObjCRuntime::MacOSX:
143 case ObjCRuntime::iOS:
144 case ObjCRuntime::WatchOS:
145 return EHPersonality::NeXT_ObjC;
146 case ObjCRuntime::GNUstep:
147 if (L.ObjCRuntime.getVersion() >= VersionTuple(1, 7))
148 return EHPersonality::GNUstep_ObjC;
149 LLVM_FALLTHROUGH;
150 case ObjCRuntime::GCC:
151 case ObjCRuntime::ObjFW:
152 if (L.hasSjLjExceptions())
153 return EHPersonality::GNU_ObjC_SJLJ;
154 if (L.hasSEHExceptions())
155 return EHPersonality::GNU_ObjC_SEH;
156 return EHPersonality::GNU_ObjC;
157 }
158 llvm_unreachable("bad runtime kind");
159}
160
161static const EHPersonality &getCXXPersonality(const TargetInfo &Target,
162 const LangOptions &L) {
163 const llvm::Triple &T = Target.getTriple();
164 if (T.isWindowsMSVCEnvironment())
165 return EHPersonality::MSVC_CxxFrameHandler3;
166 if (T.isOSAIX())
167 return EHPersonality::XL_CPlusPlus;
168 if (L.hasSjLjExceptions())
169 return EHPersonality::GNU_CPlusPlus_SJLJ;
170 if (L.hasDWARFExceptions())
171 return EHPersonality::GNU_CPlusPlus;
172 if (L.hasSEHExceptions())
173 return EHPersonality::GNU_CPlusPlus_SEH;
174 if (L.hasWasmExceptions())
175 return EHPersonality::GNU_Wasm_CPlusPlus;
176 return EHPersonality::GNU_CPlusPlus;
177}
178
179/// Determines the personality function to use when both C++
180/// and Objective-C exceptions are being caught.
181static const EHPersonality &getObjCXXPersonality(const TargetInfo &Target,
182 const LangOptions &L) {
183 if (Target.getTriple().isWindowsMSVCEnvironment())
184 return EHPersonality::MSVC_CxxFrameHandler3;
185
186 switch (L.ObjCRuntime.getKind()) {
187 // In the fragile ABI, just use C++ exception handling and hope
188 // they're not doing crazy exception mixing.
189 case ObjCRuntime::FragileMacOSX:
190 return getCXXPersonality(Target, L);
191
192 // The ObjC personality defers to the C++ personality for non-ObjC
193 // handlers. Unlike the C++ case, we use the same personality
194 // function on targets using (backend-driven) SJLJ EH.
195 case ObjCRuntime::MacOSX:
196 case ObjCRuntime::iOS:
197 case ObjCRuntime::WatchOS:
198 return getObjCPersonality(Target, L);
199
200 case ObjCRuntime::GNUstep:
201 return EHPersonality::GNU_ObjCXX;
202
203 // The GCC runtime's personality function inherently doesn't support
204 // mixed EH. Use the ObjC personality just to avoid returning null.
205 case ObjCRuntime::GCC:
206 case ObjCRuntime::ObjFW:
207 return getObjCPersonality(Target, L);
208 }
209 llvm_unreachable("bad runtime kind");
210}
211
212static const EHPersonality &getSEHPersonalityMSVC(const llvm::Triple &T) {
213 if (T.getArch() == llvm::Triple::x86)
214 return EHPersonality::MSVC_except_handler;
215 return EHPersonality::MSVC_C_specific_handler;
216}
217
218const EHPersonality &EHPersonality::get(CodeGenModule &CGM,
219 const FunctionDecl *FD) {
220 const llvm::Triple &T = CGM.getTarget().getTriple();
221 const LangOptions &L = CGM.getLangOpts();
222 const TargetInfo &Target = CGM.getTarget();
223
224 // Functions using SEH get an SEH personality.
225 if (FD && FD->usesSEHTry())
226 return getSEHPersonalityMSVC(T);
227
228 if (L.ObjC)
229 return L.CPlusPlus ? getObjCXXPersonality(Target, L)
230 : getObjCPersonality(Target, L);
231 return L.CPlusPlus ? getCXXPersonality(Target, L)
232 : getCPersonality(Target, L);
233}
234
235const EHPersonality &EHPersonality::get(CodeGenFunction &CGF) {
236 const auto *FD = CGF.CurCodeDecl;
237 // For outlined finallys and filters, use the SEH personality in case they
238 // contain more SEH. This mostly only affects finallys. Filters could
239 // hypothetically use gnu statement expressions to sneak in nested SEH.
240 FD = FD ? FD : CGF.CurSEHParent;
241 return get(CGF.CGM, dyn_cast_or_null<FunctionDecl>(FD));
242}
243
244static llvm::FunctionCallee getPersonalityFn(CodeGenModule &CGM,
245 const EHPersonality &Personality) {
246 return CGM.CreateRuntimeFunction(llvm::FunctionType::get(CGM.Int32Ty, true),
247 Personality.PersonalityFn,
248 llvm::AttributeList(), /*Local=*/true);
249}
250
251static llvm::Constant *getOpaquePersonalityFn(CodeGenModule &CGM,
252 const EHPersonality &Personality) {
253 llvm::FunctionCallee Fn = getPersonalityFn(CGM, Personality);
254 llvm::PointerType* Int8PtrTy = llvm::PointerType::get(
255 llvm::Type::getInt8Ty(CGM.getLLVMContext()),
256 CGM.getDataLayout().getProgramAddressSpace());
257
258 return llvm::ConstantExpr::getBitCast(cast<llvm::Constant>(Fn.getCallee()),
259 Int8PtrTy);
260}
261
262/// Check whether a landingpad instruction only uses C++ features.
263static bool LandingPadHasOnlyCXXUses(llvm::LandingPadInst *LPI) {
264 for (unsigned I = 0, E = LPI->getNumClauses(); I != E; ++I) {
265 // Look for something that would've been returned by the ObjC
266 // runtime's GetEHType() method.
267 llvm::Value *Val = LPI->getClause(I)->stripPointerCasts();
268 if (LPI->isCatch(I)) {
269 // Check if the catch value has the ObjC prefix.
270 if (llvm::GlobalVariable *GV = dyn_cast<llvm::GlobalVariable>(Val))
271 // ObjC EH selector entries are always global variables with
272 // names starting like this.
273 if (GV->getName().startswith("OBJC_EHTYPE"))
274 return false;
275 } else {
276 // Check if any of the filter values have the ObjC prefix.
277 llvm::Constant *CVal = cast<llvm::Constant>(Val);
278 for (llvm::User::op_iterator
279 II = CVal->op_begin(), IE = CVal->op_end(); II != IE; ++II) {
280 if (llvm::GlobalVariable *GV =
281 cast<llvm::GlobalVariable>((*II)->stripPointerCasts()))
282 // ObjC EH selector entries are always global variables with
283 // names starting like this.
284 if (GV->getName().startswith("OBJC_EHTYPE"))
285 return false;
286 }
287 }
288 }
289 return true;
290}
291
292/// Check whether a personality function could reasonably be swapped
293/// for a C++ personality function.
294static bool PersonalityHasOnlyCXXUses(llvm::Constant *Fn) {
295 for (llvm::User *U : Fn->users()) {
296 // Conditionally white-list bitcasts.
297 if (llvm::ConstantExpr *CE = dyn_cast<llvm::ConstantExpr>(U)) {
298 if (CE->getOpcode() != llvm::Instruction::BitCast) return false;
299 if (!PersonalityHasOnlyCXXUses(CE))
300 return false;
301 continue;
302 }
303
304 // Otherwise it must be a function.
305 llvm::Function *F = dyn_cast<llvm::Function>(U);
306 if (!F) return false;
307
308 for (auto BB = F->begin(), E = F->end(); BB != E; ++BB) {
309 if (BB->isLandingPad())
310 if (!LandingPadHasOnlyCXXUses(BB->getLandingPadInst()))
311 return false;
312 }
313 }
314
315 return true;
316}
317
318/// Try to use the C++ personality function in ObjC++. Not doing this
319/// can cause some incompatibilities with gcc, which is more
320/// aggressive about only using the ObjC++ personality in a function
321/// when it really needs it.
322void CodeGenModule::SimplifyPersonality() {
323 // If we're not in ObjC++ -fexceptions, there's nothing to do.
324 if (!LangOpts.CPlusPlus || !LangOpts.ObjC || !LangOpts.Exceptions)
325 return;
326
327 // Both the problem this endeavors to fix and the way the logic
328 // above works is specific to the NeXT runtime.
329 if (!LangOpts.ObjCRuntime.isNeXTFamily())
330 return;
331
332 const EHPersonality &ObjCXX = EHPersonality::get(*this, /*FD=*/nullptr);
333 const EHPersonality &CXX = getCXXPersonality(getTarget(), LangOpts);
334 if (&ObjCXX == &CXX)
335 return;
336
337 assert(std::strcmp(ObjCXX.PersonalityFn, CXX.PersonalityFn) != 0 &&
338 "Different EHPersonalities using the same personality function.");
339
340 llvm::Function *Fn = getModule().getFunction(ObjCXX.PersonalityFn);
341
342 // Nothing to do if it's unused.
343 if (!Fn || Fn->use_empty()) return;
344
345 // Can't do the optimization if it has non-C++ uses.
346 if (!PersonalityHasOnlyCXXUses(Fn)) return;
347
348 // Create the C++ personality function and kill off the old
349 // function.
350 llvm::FunctionCallee CXXFn = getPersonalityFn(*this, CXX);
351
352 // This can happen if the user is screwing with us.
353 if (Fn->getType() != CXXFn.getCallee()->getType())
354 return;
355
356 Fn->replaceAllUsesWith(CXXFn.getCallee());
357 Fn->eraseFromParent();
358}
359
360/// Returns the value to inject into a selector to indicate the
361/// presence of a catch-all.
362static llvm::Constant *getCatchAllValue(CodeGenFunction &CGF) {
363 // Possibly we should use @llvm.eh.catch.all.value here.
364 return llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
365}
366
367namespace {
368 /// A cleanup to free the exception object if its initialization
369 /// throws.
370 struct FreeException final : EHScopeStack::Cleanup {
371 llvm::Value *exn;
372 FreeException(llvm::Value *exn) : exn(exn) {}
373 void Emit(CodeGenFunction &CGF, Flags flags) override {
374 CGF.EmitNounwindRuntimeCall(getFreeExceptionFn(CGF.CGM), exn);
375 }
376 };
377} // end anonymous namespace
378
379// Emits an exception expression into the given location. This
380// differs from EmitAnyExprToMem only in that, if a final copy-ctor
381// call is required, an exception within that copy ctor causes
382// std::terminate to be invoked.
383void CodeGenFunction::EmitAnyExprToExn(const Expr *e, Address addr) {
384 // Make sure the exception object is cleaned up if there's an
385 // exception during initialization.
386 pushFullExprCleanup<FreeException>(EHCleanup, addr.getPointer());
387 EHScopeStack::stable_iterator cleanup = EHStack.stable_begin();
388
389 // __cxa_allocate_exception returns a void*; we need to cast this
390 // to the appropriate type for the object.
391 llvm::Type *ty = ConvertTypeForMem(e->getType())->getPointerTo();
392 Address typedAddr = Builder.CreateBitCast(addr, ty);
393
394 // FIXME: this isn't quite right! If there's a final unelided call
395 // to a copy constructor, then according to [except.terminate]p1 we
396 // must call std::terminate() if that constructor throws, because
397 // technically that copy occurs after the exception expression is
398 // evaluated but before the exception is caught. But the best way
399 // to handle that is to teach EmitAggExpr to do the final copy
400 // differently if it can't be elided.
401 EmitAnyExprToMem(e, typedAddr, e->getType().getQualifiers(),
402 /*IsInit*/ true);
403
404 // Deactivate the cleanup block.
405 DeactivateCleanupBlock(cleanup,
406 cast<llvm::Instruction>(typedAddr.getPointer()));
407}
408
409Address CodeGenFunction::getExceptionSlot() {
410 if (!ExceptionSlot)
411 ExceptionSlot = CreateTempAlloca(Int8PtrTy, "exn.slot");
412 return Address(ExceptionSlot, getPointerAlign());
413}
414
415Address CodeGenFunction::getEHSelectorSlot() {
416 if (!EHSelectorSlot)
417 EHSelectorSlot = CreateTempAlloca(Int32Ty, "ehselector.slot");
418 return Address(EHSelectorSlot, CharUnits::fromQuantity(4));
419}
420
421llvm::Value *CodeGenFunction::getExceptionFromSlot() {
422 return Builder.CreateLoad(getExceptionSlot(), "exn");
423}
424
425llvm::Value *CodeGenFunction::getSelectorFromSlot() {
426 return Builder.CreateLoad(getEHSelectorSlot(), "sel");
427}
428
429void CodeGenFunction::EmitCXXThrowExpr(const CXXThrowExpr *E,
430 bool KeepInsertionPoint) {
431 if (const Expr *SubExpr = E->getSubExpr()) {
432 QualType ThrowType = SubExpr->getType();
433 if (ThrowType->isObjCObjectPointerType()) {
434 const Stmt *ThrowStmt = E->getSubExpr();
435 const ObjCAtThrowStmt S(E->getExprLoc(), const_cast<Stmt *>(ThrowStmt));
436 CGM.getObjCRuntime().EmitThrowStmt(*this, S, false);
437 } else {
438 CGM.getCXXABI().emitThrow(*this, E);
439 }
440 } else {
441 CGM.getCXXABI().emitRethrow(*this, /*isNoReturn=*/true);
442 }
443
444 // throw is an expression, and the expression emitters expect us
445 // to leave ourselves at a valid insertion point.
446 if (KeepInsertionPoint)
447 EmitBlock(createBasicBlock("throw.cont"));
448}
449
450void CodeGenFunction::EmitStartEHSpec(const Decl *D) {
451 if (!CGM.getLangOpts().CXXExceptions)
452 return;
453
454 const FunctionDecl* FD = dyn_cast_or_null<FunctionDecl>(D);
455 if (!FD) {
456 // Check if CapturedDecl is nothrow and create terminate scope for it.
457 if (const CapturedDecl* CD = dyn_cast_or_null<CapturedDecl>(D)) {
458 if (CD->isNothrow())
459 EHStack.pushTerminate();
460 }
461 return;
462 }
463 const FunctionProtoType *Proto = FD->getType()->getAs<FunctionProtoType>();
464 if (!Proto)
465 return;
466
467 ExceptionSpecificationType EST = Proto->getExceptionSpecType();
468 if (isNoexceptExceptionSpec(EST) && Proto->canThrow() == CT_Cannot) {
469 // noexcept functions are simple terminate scopes.
470 EHStack.pushTerminate();
471 } else if (EST == EST_Dynamic || EST == EST_DynamicNone) {
472 // TODO: Revisit exception specifications for the MS ABI. There is a way to
473 // encode these in an object file but MSVC doesn't do anything with it.
474 if (getTarget().getCXXABI().isMicrosoft())
475 return;
476 // In wasm we currently treat 'throw()' in the same way as 'noexcept'. In
477 // case of throw with types, we ignore it and print a warning for now.
478 // TODO Correctly handle exception specification in wasm
479 if (CGM.getLangOpts().hasWasmExceptions()) {
480 if (EST == EST_DynamicNone)
481 EHStack.pushTerminate();
482 else
483 CGM.getDiags().Report(D->getLocation(),
484 diag::warn_wasm_dynamic_exception_spec_ignored)
485 << FD->getExceptionSpecSourceRange();
486 return;
487 }
488 unsigned NumExceptions = Proto->getNumExceptions();
489 EHFilterScope *Filter = EHStack.pushFilter(NumExceptions);
490
491 for (unsigned I = 0; I != NumExceptions; ++I) {
492 QualType Ty = Proto->getExceptionType(I);
493 QualType ExceptType = Ty.getNonReferenceType().getUnqualifiedType();
494 llvm::Value *EHType = CGM.GetAddrOfRTTIDescriptor(ExceptType,
495 /*ForEH=*/true);
496 Filter->setFilter(I, EHType);
497 }
498 }
499}
500
501/// Emit the dispatch block for a filter scope if necessary.
502static void emitFilterDispatchBlock(CodeGenFunction &CGF,
503 EHFilterScope &filterScope) {
504 llvm::BasicBlock *dispatchBlock = filterScope.getCachedEHDispatchBlock();
505 if (!dispatchBlock) return;
506 if (dispatchBlock->use_empty()) {
507 delete dispatchBlock;
508 return;
509 }
510
511 CGF.EmitBlockAfterUses(dispatchBlock);
512
513 // If this isn't a catch-all filter, we need to check whether we got
514 // here because the filter triggered.
515 if (filterScope.getNumFilters()) {
516 // Load the selector value.
517 llvm::Value *selector = CGF.getSelectorFromSlot();
518 llvm::BasicBlock *unexpectedBB = CGF.createBasicBlock("ehspec.unexpected");
519
520 llvm::Value *zero = CGF.Builder.getInt32(0);
521 llvm::Value *failsFilter =
522 CGF.Builder.CreateICmpSLT(selector, zero, "ehspec.fails");
523 CGF.Builder.CreateCondBr(failsFilter, unexpectedBB,
524 CGF.getEHResumeBlock(false));
525
526 CGF.EmitBlock(unexpectedBB);
527 }
528
529 // Call __cxa_call_unexpected. This doesn't need to be an invoke
530 // because __cxa_call_unexpected magically filters exceptions
531 // according to the last landing pad the exception was thrown
532 // into. Seriously.
533 llvm::Value *exn = CGF.getExceptionFromSlot();
534 CGF.EmitRuntimeCall(getUnexpectedFn(CGF.CGM), exn)
535 ->setDoesNotReturn();
536 CGF.Builder.CreateUnreachable();
537}
538
539void CodeGenFunction::EmitEndEHSpec(const Decl *D) {
540 if (!CGM.getLangOpts().CXXExceptions)
541 return;
542
543 const FunctionDecl* FD = dyn_cast_or_null<FunctionDecl>(D);
544 if (!FD) {
545 // Check if CapturedDecl is nothrow and pop terminate scope for it.
546 if (const CapturedDecl* CD = dyn_cast_or_null<CapturedDecl>(D)) {
547 if (CD->isNothrow())
548 EHStack.popTerminate();
549 }
550 return;
551 }
552 const FunctionProtoType *Proto = FD->getType()->getAs<FunctionProtoType>();
553 if (!Proto)
554 return;
555
556 ExceptionSpecificationType EST = Proto->getExceptionSpecType();
557 if (isNoexceptExceptionSpec(EST) && Proto->canThrow() == CT_Cannot) {
558 EHStack.popTerminate();
559 } else if (EST == EST_Dynamic || EST == EST_DynamicNone) {
560 // TODO: Revisit exception specifications for the MS ABI. There is a way to
561 // encode these in an object file but MSVC doesn't do anything with it.
562 if (getTarget().getCXXABI().isMicrosoft())
563 return;
564 // In wasm we currently treat 'throw()' in the same way as 'noexcept'. In
565 // case of throw with types, we ignore it and print a warning for now.
566 // TODO Correctly handle exception specification in wasm
567 if (CGM.getLangOpts().hasWasmExceptions()) {
568 if (EST == EST_DynamicNone)
569 EHStack.popTerminate();
570 return;
571 }
572 EHFilterScope &filterScope = cast<EHFilterScope>(*EHStack.begin());
573 emitFilterDispatchBlock(*this, filterScope);
574 EHStack.popFilter();
575 }
576}
577
578void CodeGenFunction::EmitCXXTryStmt(const CXXTryStmt &S) {
579 EnterCXXTryStmt(S);
580 EmitStmt(S.getTryBlock());
581 ExitCXXTryStmt(S);
582}
583
584void CodeGenFunction::EnterCXXTryStmt(const CXXTryStmt &S, bool IsFnTryBlock) {
585 unsigned NumHandlers = S.getNumHandlers();
586 EHCatchScope *CatchScope = EHStack.pushCatch(NumHandlers);
587
588 for (unsigned I = 0; I != NumHandlers; ++I) {
589 const CXXCatchStmt *C = S.getHandler(I);
590
591 llvm::BasicBlock *Handler = createBasicBlock("catch");
592 if (C->getExceptionDecl()) {
593 // FIXME: Dropping the reference type on the type into makes it
594 // impossible to correctly implement catch-by-reference
595 // semantics for pointers. Unfortunately, this is what all
596 // existing compilers do, and it's not clear that the standard
597 // personality routine is capable of doing this right. See C++ DR 388:
598 // http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#388
599 Qualifiers CaughtTypeQuals;
600 QualType CaughtType = CGM.getContext().getUnqualifiedArrayType(
601 C->getCaughtType().getNonReferenceType(), CaughtTypeQuals);
602
603 CatchTypeInfo TypeInfo{nullptr, 0};
604 if (CaughtType->isObjCObjectPointerType())
605 TypeInfo.RTTI = CGM.getObjCRuntime().GetEHType(CaughtType);
606 else
607 TypeInfo = CGM.getCXXABI().getAddrOfCXXCatchHandlerType(
608 CaughtType, C->getCaughtType());
609 CatchScope->setHandler(I, TypeInfo, Handler);
610 } else {
611 // No exception decl indicates '...', a catch-all.
612 CatchScope->setHandler(I, CGM.getCXXABI().getCatchAllTypeInfo(), Handler);
613 }
614 }
615}
616
617llvm::BasicBlock *
618CodeGenFunction::getEHDispatchBlock(EHScopeStack::stable_iterator si) {
619 if (EHPersonality::get(*this).usesFuncletPads())
620 return getFuncletEHDispatchBlock(si);
621
622 // The dispatch block for the end of the scope chain is a block that
623 // just resumes unwinding.
624 if (si == EHStack.stable_end())
625 return getEHResumeBlock(true);
626
627 // Otherwise, we should look at the actual scope.
628 EHScope &scope = *EHStack.find(si);
629
630 llvm::BasicBlock *dispatchBlock = scope.getCachedEHDispatchBlock();
631 if (!dispatchBlock) {
632 switch (scope.getKind()) {
633 case EHScope::Catch: {
634 // Apply a special case to a single catch-all.
635 EHCatchScope &catchScope = cast<EHCatchScope>(scope);
636 if (catchScope.getNumHandlers() == 1 &&
637 catchScope.getHandler(0).isCatchAll()) {
638 dispatchBlock = catchScope.getHandler(0).Block;
639
640 // Otherwise, make a dispatch block.
641 } else {
642 dispatchBlock = createBasicBlock("catch.dispatch");
643 }
644 break;
645 }
646
647 case EHScope::Cleanup:
648 dispatchBlock = createBasicBlock("ehcleanup");
649 break;
650
651 case EHScope::Filter:
652 dispatchBlock = createBasicBlock("filter.dispatch");
653 break;
654
655 case EHScope::Terminate:
656 dispatchBlock = getTerminateHandler();
657 break;
658 }
659 scope.setCachedEHDispatchBlock(dispatchBlock);
660 }
661 return dispatchBlock;
662}
663
664llvm::BasicBlock *
665CodeGenFunction::getFuncletEHDispatchBlock(EHScopeStack::stable_iterator SI) {
666 // Returning nullptr indicates that the previous dispatch block should unwind
667 // to caller.
668 if (SI == EHStack.stable_end())
669 return nullptr;
670
671 // Otherwise, we should look at the actual scope.
672 EHScope &EHS = *EHStack.find(SI);
673
674 llvm::BasicBlock *DispatchBlock = EHS.getCachedEHDispatchBlock();
675 if (DispatchBlock)
676 return DispatchBlock;
677
678 if (EHS.getKind() == EHScope::Terminate)
679 DispatchBlock = getTerminateFunclet();
680 else
681 DispatchBlock = createBasicBlock();
682 CGBuilderTy Builder(*this, DispatchBlock);
683
684 switch (EHS.getKind()) {
685 case EHScope::Catch:
686 DispatchBlock->setName("catch.dispatch");
687 break;
688
689 case EHScope::Cleanup:
690 DispatchBlock->setName("ehcleanup");
691 break;
692
693 case EHScope::Filter:
694 llvm_unreachable("exception specifications not handled yet!");
695
696 case EHScope::Terminate:
697 DispatchBlock->setName("terminate");
698 break;
699 }
700 EHS.setCachedEHDispatchBlock(DispatchBlock);
701 return DispatchBlock;
702}
703
704/// Check whether this is a non-EH scope, i.e. a scope which doesn't
705/// affect exception handling. Currently, the only non-EH scopes are
706/// normal-only cleanup scopes.
707static bool isNonEHScope(const EHScope &S) {
708 switch (S.getKind()) {
709 case EHScope::Cleanup:
710 return !cast<EHCleanupScope>(S).isEHCleanup();
711 case EHScope::Filter:
712 case EHScope::Catch:
713 case EHScope::Terminate:
714 return false;
715 }
716
717 llvm_unreachable("Invalid EHScope Kind!");
718}
719
720llvm::BasicBlock *CodeGenFunction::getInvokeDestImpl() {
721 assert(EHStack.requiresLandingPad());
722 assert(!EHStack.empty());
723
724 // If exceptions are disabled/ignored and SEH is not in use, then there is no
725 // invoke destination. SEH "works" even if exceptions are off. In practice,
726 // this means that C++ destructors and other EH cleanups don't run, which is
727 // consistent with MSVC's behavior.
728 const LangOptions &LO = CGM.getLangOpts();
729 if (!LO.Exceptions || LO.IgnoreExceptions) {
730 if (!LO.Borland && !LO.MicrosoftExt)
731 return nullptr;
732 if (!currentFunctionUsesSEHTry())
733 return nullptr;
734 }
735
736 // CUDA device code doesn't have exceptions.
737 if (LO.CUDA && LO.CUDAIsDevice)
738 return nullptr;
739
740 // Check the innermost scope for a cached landing pad. If this is
741 // a non-EH cleanup, we'll check enclosing scopes in EmitLandingPad.
742 llvm::BasicBlock *LP = EHStack.begin()->getCachedLandingPad();
743 if (LP) return LP;
744
745 const EHPersonality &Personality = EHPersonality::get(*this);
746
747 if (!CurFn->hasPersonalityFn())
748 CurFn->setPersonalityFn(getOpaquePersonalityFn(CGM, Personality));
749
750 if (Personality.usesFuncletPads()) {
751 // We don't need separate landing pads in the funclet model.
752 LP = getEHDispatchBlock(EHStack.getInnermostEHScope());
753 } else {
754 // Build the landing pad for this scope.
755 LP = EmitLandingPad();
756 }
757
758 assert(LP);
759
760 // Cache the landing pad on the innermost scope. If this is a
761 // non-EH scope, cache the landing pad on the enclosing scope, too.
762 for (EHScopeStack::iterator ir = EHStack.begin(); true; ++ir) {
763 ir->setCachedLandingPad(LP);
764 if (!isNonEHScope(*ir)) break;
765 }
766
767 return LP;
768}
769
770llvm::BasicBlock *CodeGenFunction::EmitLandingPad() {
771 assert(EHStack.requiresLandingPad());
772 assert(!CGM.getLangOpts().IgnoreExceptions &&
773 "LandingPad should not be emitted when -fignore-exceptions are in "
774 "effect.");
775 EHScope &innermostEHScope = *EHStack.find(EHStack.getInnermostEHScope());
776 switch (innermostEHScope.getKind()) {
777 case EHScope::Terminate:
778 return getTerminateLandingPad();
779
780 case EHScope::Catch:
781 case EHScope::Cleanup:
782 case EHScope::Filter:
783 if (llvm::BasicBlock *lpad = innermostEHScope.getCachedLandingPad())
784 return lpad;
785 }
786
787 // Save the current IR generation state.
788 CGBuilderTy::InsertPoint savedIP = Builder.saveAndClearIP();
789 auto DL = ApplyDebugLocation::CreateDefaultArtificial(*this, CurEHLocation);
790
791 // Create and configure the landing pad.
792 llvm::BasicBlock *lpad = createBasicBlock("lpad");
793 EmitBlock(lpad);
794
795 llvm::LandingPadInst *LPadInst =
796 Builder.CreateLandingPad(llvm::StructType::get(Int8PtrTy, Int32Ty), 0);
797
798 llvm::Value *LPadExn = Builder.CreateExtractValue(LPadInst, 0);
799 Builder.CreateStore(LPadExn, getExceptionSlot());
800 llvm::Value *LPadSel = Builder.CreateExtractValue(LPadInst, 1);
801 Builder.CreateStore(LPadSel, getEHSelectorSlot());
802
803 // Save the exception pointer. It's safe to use a single exception
804 // pointer per function because EH cleanups can never have nested
805 // try/catches.
806 // Build the landingpad instruction.
807
808 // Accumulate all the handlers in scope.
809 bool hasCatchAll = false;
810 bool hasCleanup = false;
811 bool hasFilter = false;
812 SmallVector<llvm::Value*, 4> filterTypes;
813 llvm::SmallPtrSet<llvm::Value*, 4> catchTypes;
814 for (EHScopeStack::iterator I = EHStack.begin(), E = EHStack.end(); I != E;
815 ++I) {
816
817 switch (I->getKind()) {
818 case EHScope::Cleanup:
819 // If we have a cleanup, remember that.
820 hasCleanup = (hasCleanup || cast<EHCleanupScope>(*I).isEHCleanup());
821 continue;
822
823 case EHScope::Filter: {
824 assert(I.next() == EHStack.end() && "EH filter is not end of EH stack");
825 assert(!hasCatchAll && "EH filter reached after catch-all");
826
827 // Filter scopes get added to the landingpad in weird ways.
828 EHFilterScope &filter = cast<EHFilterScope>(*I);
829 hasFilter = true;
830
831 // Add all the filter values.
832 for (unsigned i = 0, e = filter.getNumFilters(); i != e; ++i)
833 filterTypes.push_back(filter.getFilter(i));
834 goto done;
835 }
836
837 case EHScope::Terminate:
838 // Terminate scopes are basically catch-alls.
839 assert(!hasCatchAll);
840 hasCatchAll = true;
841 goto done;
842
843 case EHScope::Catch:
844 break;
845 }
846
847 EHCatchScope &catchScope = cast<EHCatchScope>(*I);
848 for (unsigned hi = 0, he = catchScope.getNumHandlers(); hi != he; ++hi) {
849 EHCatchScope::Handler handler = catchScope.getHandler(hi);
850 assert(handler.Type.Flags == 0 &&
851 "landingpads do not support catch handler flags");
852
853 // If this is a catch-all, register that and abort.
854 if (!handler.Type.RTTI) {
855 assert(!hasCatchAll);
856 hasCatchAll = true;
857 goto done;
858 }
859
860 // Check whether we already have a handler for this type.
861 if (catchTypes.insert(handler.Type.RTTI).second)
862 // If not, add it directly to the landingpad.
863 LPadInst->addClause(handler.Type.RTTI);
864 }
865 }
866
867 done:
868 // If we have a catch-all, add null to the landingpad.
869 assert(!(hasCatchAll && hasFilter));
870 if (hasCatchAll) {
871 LPadInst->addClause(getCatchAllValue(*this));
872
873 // If we have an EH filter, we need to add those handlers in the
874 // right place in the landingpad, which is to say, at the end.
875 } else if (hasFilter) {
876 // Create a filter expression: a constant array indicating which filter
877 // types there are. The personality routine only lands here if the filter
878 // doesn't match.
879 SmallVector<llvm::Constant*, 8> Filters;
880 llvm::ArrayType *AType =
881 llvm::ArrayType::get(!filterTypes.empty() ?
882 filterTypes[0]->getType() : Int8PtrTy,
883 filterTypes.size());
884
885 for (unsigned i = 0, e = filterTypes.size(); i != e; ++i)
886 Filters.push_back(cast<llvm::Constant>(filterTypes[i]));
887 llvm::Constant *FilterArray = llvm::ConstantArray::get(AType, Filters);
888 LPadInst->addClause(FilterArray);
889
890 // Also check whether we need a cleanup.
891 if (hasCleanup)
892 LPadInst->setCleanup(true);
893
894 // Otherwise, signal that we at least have cleanups.
895 } else if (hasCleanup) {
896 LPadInst->setCleanup(true);
897 }
898
899 assert((LPadInst->getNumClauses() > 0 || LPadInst->isCleanup()) &&
900 "landingpad instruction has no clauses!");
901
902 // Tell the backend how to generate the landing pad.
903 Builder.CreateBr(getEHDispatchBlock(EHStack.getInnermostEHScope()));
904
905 // Restore the old IR generation state.
906 Builder.restoreIP(savedIP);
907
908 return lpad;
909}
910
911static void emitCatchPadBlock(CodeGenFunction &CGF, EHCatchScope &CatchScope) {
912 llvm::BasicBlock *DispatchBlock = CatchScope.getCachedEHDispatchBlock();
913 assert(DispatchBlock);
914
915 CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveIP();
916 CGF.EmitBlockAfterUses(DispatchBlock);
917
918 llvm::Value *ParentPad = CGF.CurrentFuncletPad;
919 if (!ParentPad)
920 ParentPad = llvm::ConstantTokenNone::get(CGF.getLLVMContext());
921 llvm::BasicBlock *UnwindBB =
922 CGF.getEHDispatchBlock(CatchScope.getEnclosingEHScope());
923
924 unsigned NumHandlers = CatchScope.getNumHandlers();
925 llvm::CatchSwitchInst *CatchSwitch =
926 CGF.Builder.CreateCatchSwitch(ParentPad, UnwindBB, NumHandlers);
927
928 // Test against each of the exception types we claim to catch.
929 for (unsigned I = 0; I < NumHandlers; ++I) {
930 const EHCatchScope::Handler &Handler = CatchScope.getHandler(I);
931
932 CatchTypeInfo TypeInfo = Handler.Type;
933 if (!TypeInfo.RTTI)
934 TypeInfo.RTTI = llvm::Constant::getNullValue(CGF.VoidPtrTy);
935
936 CGF.Builder.SetInsertPoint(Handler.Block);
937
938 if (EHPersonality::get(CGF).isMSVCXXPersonality()) {
939 CGF.Builder.CreateCatchPad(
940 CatchSwitch, {TypeInfo.RTTI, CGF.Builder.getInt32(TypeInfo.Flags),
941 llvm::Constant::getNullValue(CGF.VoidPtrTy)});
942 } else {
943 CGF.Builder.CreateCatchPad(CatchSwitch, {TypeInfo.RTTI});
944 }
945
946 CatchSwitch->addHandler(Handler.Block);
947 }
948 CGF.Builder.restoreIP(SavedIP);
949}
950
951// Wasm uses Windows-style EH instructions, but it merges all catch clauses into
952// one big catchpad, within which we use Itanium's landingpad-style selector
953// comparison instructions.
954static void emitWasmCatchPadBlock(CodeGenFunction &CGF,
955 EHCatchScope &CatchScope) {
956 llvm::BasicBlock *DispatchBlock = CatchScope.getCachedEHDispatchBlock();
957 assert(DispatchBlock);
958
959 CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveIP();
960 CGF.EmitBlockAfterUses(DispatchBlock);
961
962 llvm::Value *ParentPad = CGF.CurrentFuncletPad;
963 if (!ParentPad)
964 ParentPad = llvm::ConstantTokenNone::get(CGF.getLLVMContext());
965 llvm::BasicBlock *UnwindBB =
966 CGF.getEHDispatchBlock(CatchScope.getEnclosingEHScope());
967
968 unsigned NumHandlers = CatchScope.getNumHandlers();
969 llvm::CatchSwitchInst *CatchSwitch =
970 CGF.Builder.CreateCatchSwitch(ParentPad, UnwindBB, NumHandlers);
971
972 // We don't use a landingpad instruction, so generate intrinsic calls to
973 // provide exception and selector values.
974 llvm::BasicBlock *WasmCatchStartBlock = CGF.createBasicBlock("catch.start");
975 CatchSwitch->addHandler(WasmCatchStartBlock);
976 CGF.EmitBlockAfterUses(WasmCatchStartBlock);
977
978 // Create a catchpad instruction.
979 SmallVector<llvm::Value *, 4> CatchTypes;
980 for (unsigned I = 0, E = NumHandlers; I < E; ++I) {
981 const EHCatchScope::Handler &Handler = CatchScope.getHandler(I);
982 CatchTypeInfo TypeInfo = Handler.Type;
983 if (!TypeInfo.RTTI)
984 TypeInfo.RTTI = llvm::Constant::getNullValue(CGF.VoidPtrTy);
985 CatchTypes.push_back(TypeInfo.RTTI);
986 }
987 auto *CPI = CGF.Builder.CreateCatchPad(CatchSwitch, CatchTypes);
988
989 // Create calls to wasm.get.exception and wasm.get.ehselector intrinsics.
990 // Before they are lowered appropriately later, they provide values for the
991 // exception and selector.
992 llvm::Function *GetExnFn =
993 CGF.CGM.getIntrinsic(llvm::Intrinsic::wasm_get_exception);
994 llvm::Function *GetSelectorFn =
995 CGF.CGM.getIntrinsic(llvm::Intrinsic::wasm_get_ehselector);
996 llvm::CallInst *Exn = CGF.Builder.CreateCall(GetExnFn, CPI);
997 CGF.Builder.CreateStore(Exn, CGF.getExceptionSlot());
998 llvm::CallInst *Selector = CGF.Builder.CreateCall(GetSelectorFn, CPI);
999
1000 llvm::Function *TypeIDFn = CGF.CGM.getIntrinsic(llvm::Intrinsic::eh_typeid_for);
1001
1002 // If there's only a single catch-all, branch directly to its handler.
1003 if (CatchScope.getNumHandlers() == 1 &&
1004 CatchScope.getHandler(0).isCatchAll()) {
1005 CGF.Builder.CreateBr(CatchScope.getHandler(0).Block);
1006 CGF.Builder.restoreIP(SavedIP);
1007 return;
1008 }
1009
1010 // Test against each of the exception types we claim to catch.
1011 for (unsigned I = 0, E = NumHandlers;; ++I) {
1012 assert(I < E && "ran off end of handlers!");
1013 const EHCatchScope::Handler &Handler = CatchScope.getHandler(I);
1014 CatchTypeInfo TypeInfo = Handler.Type;
1015 if (!TypeInfo.RTTI)
1016 TypeInfo.RTTI = llvm::Constant::getNullValue(CGF.VoidPtrTy);
1017
1018 // Figure out the next block.
1019 llvm::BasicBlock *NextBlock;
1020
1021 bool EmitNextBlock = false, NextIsEnd = false;
1022
1023 // If this is the last handler, we're at the end, and the next block is a
1024 // block that contains a call to the rethrow function, so we can unwind to
1025 // the enclosing EH scope. The call itself will be generated later.
1026 if (I + 1 == E) {
1027 NextBlock = CGF.createBasicBlock("rethrow");
1028 EmitNextBlock = true;
1029 NextIsEnd = true;
1030
1031 // If the next handler is a catch-all, we're at the end, and the
1032 // next block is that handler.
1033 } else if (CatchScope.getHandler(I + 1).isCatchAll()) {
1034 NextBlock = CatchScope.getHandler(I + 1).Block;
1035 NextIsEnd = true;
1036
1037 // Otherwise, we're not at the end and we need a new block.
1038 } else {
1039 NextBlock = CGF.createBasicBlock("catch.fallthrough");
1040 EmitNextBlock = true;
1041 }
1042
1043 // Figure out the catch type's index in the LSDA's type table.
1044 llvm::CallInst *TypeIndex = CGF.Builder.CreateCall(TypeIDFn, TypeInfo.RTTI);
1045 TypeIndex->setDoesNotThrow();
1046
1047 llvm::Value *MatchesTypeIndex =
1048 CGF.Builder.CreateICmpEQ(Selector, TypeIndex, "matches");
1049 CGF.Builder.CreateCondBr(MatchesTypeIndex, Handler.Block, NextBlock);
1050
1051 if (EmitNextBlock)
1052 CGF.EmitBlock(NextBlock);
1053 if (NextIsEnd)
1054 break;
1055 }
1056
1057 CGF.Builder.restoreIP(SavedIP);
1058}
1059
1060/// Emit the structure of the dispatch block for the given catch scope.
1061/// It is an invariant that the dispatch block already exists.
1062static void emitCatchDispatchBlock(CodeGenFunction &CGF,
1063 EHCatchScope &catchScope) {
1064 if (EHPersonality::get(CGF).isWasmPersonality())
1065 return emitWasmCatchPadBlock(CGF, catchScope);
1066 if (EHPersonality::get(CGF).usesFuncletPads())
1067 return emitCatchPadBlock(CGF, catchScope);
1068
1069 llvm::BasicBlock *dispatchBlock = catchScope.getCachedEHDispatchBlock();
1070 assert(dispatchBlock);
1071
1072 // If there's only a single catch-all, getEHDispatchBlock returned
1073 // that catch-all as the dispatch block.
1074 if (catchScope.getNumHandlers() == 1 &&
1075 catchScope.getHandler(0).isCatchAll()) {
1076 assert(dispatchBlock == catchScope.getHandler(0).Block);
1077 return;
1078 }
1079
1080 CGBuilderTy::InsertPoint savedIP = CGF.Builder.saveIP();
1081 CGF.EmitBlockAfterUses(dispatchBlock);
1082
1083 // Select the right handler.
1084 llvm::Function *llvm_eh_typeid_for =
1085 CGF.CGM.getIntrinsic(llvm::Intrinsic::eh_typeid_for);
1086
1087 // Load the selector value.
1088 llvm::Value *selector = CGF.getSelectorFromSlot();
1089
1090 // Test against each of the exception types we claim to catch.
1091 for (unsigned i = 0, e = catchScope.getNumHandlers(); ; ++i) {
1092 assert(i < e && "ran off end of handlers!");
1093 const EHCatchScope::Handler &handler = catchScope.getHandler(i);
1094
1095 llvm::Value *typeValue = handler.Type.RTTI;
1096 assert(handler.Type.Flags == 0 &&
1097 "landingpads do not support catch handler flags");
1098 assert(typeValue && "fell into catch-all case!");
1099 typeValue = CGF.Builder.CreateBitCast(typeValue, CGF.Int8PtrTy);
1100
1101 // Figure out the next block.
1102 bool nextIsEnd;
1103 llvm::BasicBlock *nextBlock;
1104
1105 // If this is the last handler, we're at the end, and the next
1106 // block is the block for the enclosing EH scope.
1107 if (i + 1 == e) {
1108 nextBlock = CGF.getEHDispatchBlock(catchScope.getEnclosingEHScope());
1109 nextIsEnd = true;
1110
1111 // If the next handler is a catch-all, we're at the end, and the
1112 // next block is that handler.
1113 } else if (catchScope.getHandler(i+1).isCatchAll()) {
1114 nextBlock = catchScope.getHandler(i+1).Block;
1115 nextIsEnd = true;
1116
1117 // Otherwise, we're not at the end and we need a new block.
1118 } else {
1119 nextBlock = CGF.createBasicBlock("catch.fallthrough");
1120 nextIsEnd = false;
1121 }
1122
1123 // Figure out the catch type's index in the LSDA's type table.
1124 llvm::CallInst *typeIndex =
1125 CGF.Builder.CreateCall(llvm_eh_typeid_for, typeValue);
1126 typeIndex->setDoesNotThrow();
1127
1128 llvm::Value *matchesTypeIndex =
1129 CGF.Builder.CreateICmpEQ(selector, typeIndex, "matches");
1130 CGF.Builder.CreateCondBr(matchesTypeIndex, handler.Block, nextBlock);
1131
1132 // If the next handler is a catch-all, we're completely done.
1133 if (nextIsEnd) {
1134 CGF.Builder.restoreIP(savedIP);
1135 return;
1136 }
1137 // Otherwise we need to emit and continue at that block.
1138 CGF.EmitBlock(nextBlock);
1139 }
1140}
1141
1142void CodeGenFunction::popCatchScope() {
1143 EHCatchScope &catchScope = cast<EHCatchScope>(*EHStack.begin());
1144 if (catchScope.hasEHBranches())
1145 emitCatchDispatchBlock(*this, catchScope);
1146 EHStack.popCatch();
1147}
1148
1149void CodeGenFunction::ExitCXXTryStmt(const CXXTryStmt &S, bool IsFnTryBlock) {
1150 unsigned NumHandlers = S.getNumHandlers();
1151 EHCatchScope &CatchScope = cast<EHCatchScope>(*EHStack.begin());
1152 assert(CatchScope.getNumHandlers() == NumHandlers);
1153 llvm::BasicBlock *DispatchBlock = CatchScope.getCachedEHDispatchBlock();
1154
1155 // If the catch was not required, bail out now.
1156 if (!CatchScope.hasEHBranches()) {
1157 CatchScope.clearHandlerBlocks();
1158 EHStack.popCatch();
1159 return;
1160 }
1161
1162 // Emit the structure of the EH dispatch for this catch.
1163 emitCatchDispatchBlock(*this, CatchScope);
1164
1165 // Copy the handler blocks off before we pop the EH stack. Emitting
1166 // the handlers might scribble on this memory.
1167 SmallVector<EHCatchScope::Handler, 8> Handlers(
1168 CatchScope.begin(), CatchScope.begin() + NumHandlers);
1169
1170 EHStack.popCatch();
1171
1172 // The fall-through block.
1173 llvm::BasicBlock *ContBB = createBasicBlock("try.cont");
1174
1175 // We just emitted the body of the try; jump to the continue block.
1176 if (HaveInsertPoint())
1177 Builder.CreateBr(ContBB);
1178
1179 // Determine if we need an implicit rethrow for all these catch handlers;
1180 // see the comment below.
1181 bool doImplicitRethrow = false;
1182 if (IsFnTryBlock)
1183 doImplicitRethrow = isa<CXXDestructorDecl>(CurCodeDecl) ||
1184 isa<CXXConstructorDecl>(CurCodeDecl);
1185
1186 // Wasm uses Windows-style EH instructions, but merges all catch clauses into
1187 // one big catchpad. So we save the old funclet pad here before we traverse
1188 // each catch handler.
1189 SaveAndRestore<llvm::Instruction *> RestoreCurrentFuncletPad(
1190 CurrentFuncletPad);
1191 llvm::BasicBlock *WasmCatchStartBlock = nullptr;
1192 if (EHPersonality::get(*this).isWasmPersonality()) {
1193 auto *CatchSwitch =
1194 cast<llvm::CatchSwitchInst>(DispatchBlock->getFirstNonPHI());
1195 WasmCatchStartBlock = CatchSwitch->hasUnwindDest()
1196 ? CatchSwitch->getSuccessor(1)
1197 : CatchSwitch->getSuccessor(0);
1198 auto *CPI = cast<llvm::CatchPadInst>(WasmCatchStartBlock->getFirstNonPHI());
1199 CurrentFuncletPad = CPI;
1200 }
1201
1202 // Perversely, we emit the handlers backwards precisely because we
1203 // want them to appear in source order. In all of these cases, the
1204 // catch block will have exactly one predecessor, which will be a
1205 // particular block in the catch dispatch. However, in the case of
1206 // a catch-all, one of the dispatch blocks will branch to two
1207 // different handlers, and EmitBlockAfterUses will cause the second
1208 // handler to be moved before the first.
1209 bool HasCatchAll = false;
1210 for (unsigned I = NumHandlers; I != 0; --I) {
1211 HasCatchAll |= Handlers[I - 1].isCatchAll();
1212 llvm::BasicBlock *CatchBlock = Handlers[I-1].Block;
1213 EmitBlockAfterUses(CatchBlock);
1214
1215 // Catch the exception if this isn't a catch-all.
1216 const CXXCatchStmt *C = S.getHandler(I-1);
1217
1218 // Enter a cleanup scope, including the catch variable and the
1219 // end-catch.
1220 RunCleanupsScope CatchScope(*this);
1221
1222 // Initialize the catch variable and set up the cleanups.
1223 SaveAndRestore<llvm::Instruction *> RestoreCurrentFuncletPad(
1224 CurrentFuncletPad);
1225 CGM.getCXXABI().emitBeginCatch(*this, C);
1226
1227 // Emit the PGO counter increment.
1228 incrementProfileCounter(C);
1229
1230 // Perform the body of the catch.
1231 EmitStmt(C->getHandlerBlock());
1232
1233 // [except.handle]p11:
1234 // The currently handled exception is rethrown if control
1235 // reaches the end of a handler of the function-try-block of a
1236 // constructor or destructor.
1237
1238 // It is important that we only do this on fallthrough and not on
1239 // return. Note that it's illegal to put a return in a
1240 // constructor function-try-block's catch handler (p14), so this
1241 // really only applies to destructors.
1242 if (doImplicitRethrow && HaveInsertPoint()) {
1243 CGM.getCXXABI().emitRethrow(*this, /*isNoReturn*/false);
1244 Builder.CreateUnreachable();
1245 Builder.ClearInsertionPoint();
1246 }
1247
1248 // Fall out through the catch cleanups.
1249 CatchScope.ForceCleanup();
1250
1251 // Branch out of the try.
1252 if (HaveInsertPoint())
1253 Builder.CreateBr(ContBB);
1254 }
1255
1256 // Because in wasm we merge all catch clauses into one big catchpad, in case
1257 // none of the types in catch handlers matches after we test against each of
1258 // them, we should unwind to the next EH enclosing scope. We generate a call
1259 // to rethrow function here to do that.
1260 if (EHPersonality::get(*this).isWasmPersonality() && !HasCatchAll) {
1261 assert(WasmCatchStartBlock);
1262 // Navigate for the "rethrow" block we created in emitWasmCatchPadBlock().
1263 // Wasm uses landingpad-style conditional branches to compare selectors, so
1264 // we follow the false destination for each of the cond branches to reach
1265 // the rethrow block.
1266 llvm::BasicBlock *RethrowBlock = WasmCatchStartBlock;
1267 while (llvm::Instruction *TI = RethrowBlock->getTerminator()) {
1268 auto *BI = cast<llvm::BranchInst>(TI);
1269 assert(BI->isConditional());
1270 RethrowBlock = BI->getSuccessor(1);
1271 }
1272 assert(RethrowBlock != WasmCatchStartBlock && RethrowBlock->empty());
1273 Builder.SetInsertPoint(RethrowBlock);
1274 llvm::Function *RethrowInCatchFn =
1275 CGM.getIntrinsic(llvm::Intrinsic::wasm_rethrow);
1276 EmitNoreturnRuntimeCallOrInvoke(RethrowInCatchFn, {});
1277 }
1278
1279 EmitBlock(ContBB);
1280 incrementProfileCounter(&S);
1281}
1282
1283namespace {
1284 struct CallEndCatchForFinally final : EHScopeStack::Cleanup {
1285 llvm::Value *ForEHVar;
1286 llvm::FunctionCallee EndCatchFn;
1287 CallEndCatchForFinally(llvm::Value *ForEHVar,
1288 llvm::FunctionCallee EndCatchFn)
1289 : ForEHVar(ForEHVar), EndCatchFn(EndCatchFn) {}
1290
1291 void Emit(CodeGenFunction &CGF, Flags flags) override {
1292 llvm::BasicBlock *EndCatchBB = CGF.createBasicBlock("finally.endcatch");
1293 llvm::BasicBlock *CleanupContBB =
1294 CGF.createBasicBlock("finally.cleanup.cont");
1295
1296 llvm::Value *ShouldEndCatch =
1297 CGF.Builder.CreateFlagLoad(ForEHVar, "finally.endcatch");
1298 CGF.Builder.CreateCondBr(ShouldEndCatch, EndCatchBB, CleanupContBB);
1299 CGF.EmitBlock(EndCatchBB);
1300 CGF.EmitRuntimeCallOrInvoke(EndCatchFn); // catch-all, so might throw
1301 CGF.EmitBlock(CleanupContBB);
1302 }
1303 };
1304
1305 struct PerformFinally final : EHScopeStack::Cleanup {
1306 const Stmt *Body;
1307 llvm::Value *ForEHVar;
1308 llvm::FunctionCallee EndCatchFn;
1309 llvm::FunctionCallee RethrowFn;
1310 llvm::Value *SavedExnVar;
1311
1312 PerformFinally(const Stmt *Body, llvm::Value *ForEHVar,
1313 llvm::FunctionCallee EndCatchFn,
1314 llvm::FunctionCallee RethrowFn, llvm::Value *SavedExnVar)
1315 : Body(Body), ForEHVar(ForEHVar), EndCatchFn(EndCatchFn),
1316 RethrowFn(RethrowFn), SavedExnVar(SavedExnVar) {}
1317
1318 void Emit(CodeGenFunction &CGF, Flags flags) override {
1319 // Enter a cleanup to call the end-catch function if one was provided.
1320 if (EndCatchFn)
1321 CGF.EHStack.pushCleanup<CallEndCatchForFinally>(NormalAndEHCleanup,
1322 ForEHVar, EndCatchFn);
1323
1324 // Save the current cleanup destination in case there are
1325 // cleanups in the finally block.
1326 llvm::Value *SavedCleanupDest =
1327 CGF.Builder.CreateLoad(CGF.getNormalCleanupDestSlot(),
1328 "cleanup.dest.saved");
1329
1330 // Emit the finally block.
1331 CGF.EmitStmt(Body);
1332
1333 // If the end of the finally is reachable, check whether this was
1334 // for EH. If so, rethrow.
1335 if (CGF.HaveInsertPoint()) {
1336 llvm::BasicBlock *RethrowBB = CGF.createBasicBlock("finally.rethrow");
1337 llvm::BasicBlock *ContBB = CGF.createBasicBlock("finally.cont");
1338
1339 llvm::Value *ShouldRethrow =
1340 CGF.Builder.CreateFlagLoad(ForEHVar, "finally.shouldthrow");
1341 CGF.Builder.CreateCondBr(ShouldRethrow, RethrowBB, ContBB);
1342
1343 CGF.EmitBlock(RethrowBB);
1344 if (SavedExnVar) {
1345 CGF.EmitRuntimeCallOrInvoke(RethrowFn,
1346 CGF.Builder.CreateAlignedLoad(CGF.Int8PtrTy, SavedExnVar,
1347 CGF.getPointerAlign()));
1348 } else {
1349 CGF.EmitRuntimeCallOrInvoke(RethrowFn);
1350 }
1351 CGF.Builder.CreateUnreachable();
1352
1353 CGF.EmitBlock(ContBB);
1354
1355 // Restore the cleanup destination.
1356 CGF.Builder.CreateStore(SavedCleanupDest,
1357 CGF.getNormalCleanupDestSlot());
1358 }
1359
1360 // Leave the end-catch cleanup. As an optimization, pretend that
1361 // the fallthrough path was inaccessible; we've dynamically proven
1362 // that we're not in the EH case along that path.
1363 if (EndCatchFn) {
1364 CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveAndClearIP();
1365 CGF.PopCleanupBlock();
1366 CGF.Builder.restoreIP(SavedIP);
1367 }
1368
1369 // Now make sure we actually have an insertion point or the
1370 // cleanup gods will hate us.
1371 CGF.EnsureInsertPoint();
1372 }
1373 };
1374} // end anonymous namespace
1375
1376/// Enters a finally block for an implementation using zero-cost
1377/// exceptions. This is mostly general, but hard-codes some
1378/// language/ABI-specific behavior in the catch-all sections.
1379void CodeGenFunction::FinallyInfo::enter(CodeGenFunction &CGF, const Stmt *body,
1380 llvm::FunctionCallee beginCatchFn,
1381 llvm::FunctionCallee endCatchFn,
1382 llvm::FunctionCallee rethrowFn) {
1383 assert((!!beginCatchFn) == (!!endCatchFn) &&
1384 "begin/end catch functions not paired");
1385 assert(rethrowFn && "rethrow function is required");
1386
1387 BeginCatchFn = beginCatchFn;
1388
1389 // The rethrow function has one of the following two types:
1390 // void (*)()
1391 // void (*)(void*)
1392 // In the latter case we need to pass it the exception object.
1393 // But we can't use the exception slot because the @finally might
1394 // have a landing pad (which would overwrite the exception slot).
1395 llvm::FunctionType *rethrowFnTy = rethrowFn.getFunctionType();
1396 SavedExnVar = nullptr;
1397 if (rethrowFnTy->getNumParams())
1398 SavedExnVar = CGF.CreateTempAlloca(CGF.Int8PtrTy, "finally.exn");
1399
1400 // A finally block is a statement which must be executed on any edge
1401 // out of a given scope. Unlike a cleanup, the finally block may
1402 // contain arbitrary control flow leading out of itself. In
1403 // addition, finally blocks should always be executed, even if there
1404 // are no catch handlers higher on the stack. Therefore, we
1405 // surround the protected scope with a combination of a normal
1406 // cleanup (to catch attempts to break out of the block via normal
1407 // control flow) and an EH catch-all (semantically "outside" any try
1408 // statement to which the finally block might have been attached).
1409 // The finally block itself is generated in the context of a cleanup
1410 // which conditionally leaves the catch-all.
1411
1412 // Jump destination for performing the finally block on an exception
1413 // edge. We'll never actually reach this block, so unreachable is
1414 // fine.
1415 RethrowDest = CGF.getJumpDestInCurrentScope(CGF.getUnreachableBlock());
1416
1417 // Whether the finally block is being executed for EH purposes.
1418 ForEHVar = CGF.CreateTempAlloca(CGF.Builder.getInt1Ty(), "finally.for-eh");
1419 CGF.Builder.CreateFlagStore(false, ForEHVar);
1420
1421 // Enter a normal cleanup which will perform the @finally block.
1422 CGF.EHStack.pushCleanup<PerformFinally>(NormalCleanup, body,
1423 ForEHVar, endCatchFn,
1424 rethrowFn, SavedExnVar);
1425
1426 // Enter a catch-all scope.
1427 llvm::BasicBlock *catchBB = CGF.createBasicBlock("finally.catchall");
1428 EHCatchScope *catchScope = CGF.EHStack.pushCatch(1);
1429 catchScope->setCatchAllHandler(0, catchBB);
1430}
1431
1432void CodeGenFunction::FinallyInfo::exit(CodeGenFunction &CGF) {
1433 // Leave the finally catch-all.
1434 EHCatchScope &catchScope = cast<EHCatchScope>(*CGF.EHStack.begin());
1435 llvm::BasicBlock *catchBB = catchScope.getHandler(0).Block;
1436
1437 CGF.popCatchScope();
1438
1439 // If there are any references to the catch-all block, emit it.
1440 if (catchBB->use_empty()) {
1441 delete catchBB;
1442 } else {
1443 CGBuilderTy::InsertPoint savedIP = CGF.Builder.saveAndClearIP();
1444 CGF.EmitBlock(catchBB);
1445
1446 llvm::Value *exn = nullptr;
1447
1448 // If there's a begin-catch function, call it.
1449 if (BeginCatchFn) {
1450 exn = CGF.getExceptionFromSlot();
1451 CGF.EmitNounwindRuntimeCall(BeginCatchFn, exn);
1452 }
1453
1454 // If we need to remember the exception pointer to rethrow later, do so.
1455 if (SavedExnVar) {
1456 if (!exn) exn = CGF.getExceptionFromSlot();
1457 CGF.Builder.CreateAlignedStore(exn, SavedExnVar, CGF.getPointerAlign());
1458 }
1459
1460 // Tell the cleanups in the finally block that we're do this for EH.
1461 CGF.Builder.CreateFlagStore(true, ForEHVar);
1462
1463 // Thread a jump through the finally cleanup.
1464 CGF.EmitBranchThroughCleanup(RethrowDest);
1465
1466 CGF.Builder.restoreIP(savedIP);
1467 }
1468
1469 // Finally, leave the @finally cleanup.
1470 CGF.PopCleanupBlock();
1471}
1472
1473llvm::BasicBlock *CodeGenFunction::getTerminateLandingPad() {
1474 if (TerminateLandingPad)
1475 return TerminateLandingPad;
1476
1477 CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
1478
1479 // This will get inserted at the end of the function.
1480 TerminateLandingPad = createBasicBlock("terminate.lpad");
1481 Builder.SetInsertPoint(TerminateLandingPad);
1482
1483 // Tell the backend that this is a landing pad.
1484 const EHPersonality &Personality = EHPersonality::get(*this);
1485
1486 if (!CurFn->hasPersonalityFn())
1487 CurFn->setPersonalityFn(getOpaquePersonalityFn(CGM, Personality));
1488
1489 llvm::LandingPadInst *LPadInst =
1490 Builder.CreateLandingPad(llvm::StructType::get(Int8PtrTy, Int32Ty), 0);
1491 LPadInst->addClause(getCatchAllValue(*this));
1492
1493 llvm::Value *Exn = nullptr;
1494 if (getLangOpts().CPlusPlus)
1495 Exn = Builder.CreateExtractValue(LPadInst, 0);
1496 llvm::CallInst *terminateCall =
1497 CGM.getCXXABI().emitTerminateForUnexpectedException(*this, Exn);
1498 terminateCall->setDoesNotReturn();
1499 Builder.CreateUnreachable();
1500
1501 // Restore the saved insertion state.
1502 Builder.restoreIP(SavedIP);
1503
1504 return TerminateLandingPad;
1505}
1506
1507llvm::BasicBlock *CodeGenFunction::getTerminateHandler() {
1508 if (TerminateHandler)
1509 return TerminateHandler;
1510
1511 // Set up the terminate handler. This block is inserted at the very
1512 // end of the function by FinishFunction.
1513 TerminateHandler = createBasicBlock("terminate.handler");
1514 CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
1515 Builder.SetInsertPoint(TerminateHandler);
1516
1517 llvm::Value *Exn = nullptr;
1518 if (getLangOpts().CPlusPlus)
1519 Exn = getExceptionFromSlot();
1520 llvm::CallInst *terminateCall =
1521 CGM.getCXXABI().emitTerminateForUnexpectedException(*this, Exn);
1522 terminateCall->setDoesNotReturn();
1523 Builder.CreateUnreachable();
1524
1525 // Restore the saved insertion state.
1526 Builder.restoreIP(SavedIP);
1527
1528 return TerminateHandler;
1529}
1530
1531llvm::BasicBlock *CodeGenFunction::getTerminateFunclet() {
1532 assert(EHPersonality::get(*this).usesFuncletPads() &&
1533 "use getTerminateLandingPad for non-funclet EH");
1534
1535 llvm::BasicBlock *&TerminateFunclet = TerminateFunclets[CurrentFuncletPad];
1536 if (TerminateFunclet)
1537 return TerminateFunclet;
1538
1539 CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
1540
1541 // Set up the terminate handler. This block is inserted at the very
1542 // end of the function by FinishFunction.
1543 TerminateFunclet = createBasicBlock("terminate.handler");
1544 Builder.SetInsertPoint(TerminateFunclet);
1545
1546 // Create the cleanuppad using the current parent pad as its token. Use 'none'
1547 // if this is a top-level terminate scope, which is the common case.
1548 SaveAndRestore<llvm::Instruction *> RestoreCurrentFuncletPad(
1549 CurrentFuncletPad);
1550 llvm::Value *ParentPad = CurrentFuncletPad;
1551 if (!ParentPad)
1552 ParentPad = llvm::ConstantTokenNone::get(CGM.getLLVMContext());
1553 CurrentFuncletPad = Builder.CreateCleanupPad(ParentPad);
1554
1555 // Emit the __std_terminate call.
1556 llvm::CallInst *terminateCall =
1557 CGM.getCXXABI().emitTerminateForUnexpectedException(*this, nullptr);
1558 terminateCall->setDoesNotReturn();
1559 Builder.CreateUnreachable();
1560
1561 // Restore the saved insertion state.
1562 Builder.restoreIP(SavedIP);
1563
1564 return TerminateFunclet;
1565}
1566
1567llvm::BasicBlock *CodeGenFunction::getEHResumeBlock(bool isCleanup) {
1568 if (EHResumeBlock) return EHResumeBlock;
1569
1570 CGBuilderTy::InsertPoint SavedIP = Builder.saveIP();
1571
1572 // We emit a jump to a notional label at the outermost unwind state.
1573 EHResumeBlock = createBasicBlock("eh.resume");
1574 Builder.SetInsertPoint(EHResumeBlock);
1575
1576 const EHPersonality &Personality = EHPersonality::get(*this);
1577
1578 // This can always be a call because we necessarily didn't find
1579 // anything on the EH stack which needs our help.
1580 const char *RethrowName = Personality.CatchallRethrowFn;
1581 if (RethrowName != nullptr && !isCleanup) {
1582 EmitRuntimeCall(getCatchallRethrowFn(CGM, RethrowName),
1583 getExceptionFromSlot())->setDoesNotReturn();
1584 Builder.CreateUnreachable();
1585 Builder.restoreIP(SavedIP);
1586 return EHResumeBlock;
1587 }
1588
1589 // Recreate the landingpad's return value for the 'resume' instruction.
1590 llvm::Value *Exn = getExceptionFromSlot();
1591 llvm::Value *Sel = getSelectorFromSlot();
1592
1593 llvm::Type *LPadType = llvm::StructType::get(Exn->getType(), Sel->getType());
1594 llvm::Value *LPadVal = llvm::UndefValue::get(LPadType);
1595 LPadVal = Builder.CreateInsertValue(LPadVal, Exn, 0, "lpad.val");
1596 LPadVal = Builder.CreateInsertValue(LPadVal, Sel, 1, "lpad.val");
1597
1598 Builder.CreateResume(LPadVal);
1599 Builder.restoreIP(SavedIP);
1600 return EHResumeBlock;
1601}
1602
1603void CodeGenFunction::EmitSEHTryStmt(const SEHTryStmt &S) {
1604 EnterSEHTryStmt(S);
1605 {
1606 JumpDest TryExit = getJumpDestInCurrentScope("__try.__leave");
1607
1608 SEHTryEpilogueStack.push_back(&TryExit);
1609 EmitStmt(S.getTryBlock());
1610 SEHTryEpilogueStack.pop_back();
1611
1612 if (!TryExit.getBlock()->use_empty())
1613 EmitBlock(TryExit.getBlock(), /*IsFinished=*/true);
1614 else
1615 delete TryExit.getBlock();
1616 }
1617 ExitSEHTryStmt(S);
1618}
1619
1620namespace {
1621struct PerformSEHFinally final : EHScopeStack::Cleanup {
1622 llvm::Function *OutlinedFinally;
1623 PerformSEHFinally(llvm::Function *OutlinedFinally)
1624 : OutlinedFinally(OutlinedFinally) {}
1625
1626 void Emit(CodeGenFunction &CGF, Flags F) override {
1627 ASTContext &Context = CGF.getContext();
1628 CodeGenModule &CGM = CGF.CGM;
1629
1630 CallArgList Args;
1631
1632 // Compute the two argument values.
1633 QualType ArgTys[2] = {Context.UnsignedCharTy, Context.VoidPtrTy};
1634 llvm::Value *FP = nullptr;
1635 // If CFG.IsOutlinedSEHHelper is true, then we are within a finally block.
1636 if (CGF.IsOutlinedSEHHelper) {
1637 FP = &CGF.CurFn->arg_begin()[1];
1638 } else {
1639 llvm::Function *LocalAddrFn =
1640 CGM.getIntrinsic(llvm::Intrinsic::localaddress);
1641 FP = CGF.Builder.CreateCall(LocalAddrFn);
1642 }
1643
1644 llvm::Value *IsForEH =
1645 llvm::ConstantInt::get(CGF.ConvertType(ArgTys[0]), F.isForEHCleanup());
1646
1647 // Except _leave and fall-through at the end, all other exits in a _try
1648 // (return/goto/continue/break) are considered as abnormal terminations
1649 // since _leave/fall-through is always Indexed 0,
1650 // just use NormalCleanupDestSlot (>= 1 for goto/return/..),
1651 // as 1st Arg to indicate abnormal termination
1652 if (!F.isForEHCleanup() && F.hasExitSwitch()) {
1653 Address Addr = CGF.getNormalCleanupDestSlot();
1654 llvm::Value *Load = CGF.Builder.CreateLoad(Addr, "cleanup.dest");
1655 llvm::Value *Zero = llvm::Constant::getNullValue(CGM.Int32Ty);
1656 IsForEH = CGF.Builder.CreateICmpNE(Load, Zero);
1657 }
1658
1659 Args.add(RValue::get(IsForEH), ArgTys[0]);
1660 Args.add(RValue::get(FP), ArgTys[1]);
1661
1662 // Arrange a two-arg function info and type.
1663 const CGFunctionInfo &FnInfo =
1664 CGM.getTypes().arrangeBuiltinFunctionCall(Context.VoidTy, Args);
1665
1666 auto Callee = CGCallee::forDirect(OutlinedFinally);
1667 CGF.EmitCall(FnInfo, Callee, ReturnValueSlot(), Args);
1668 }
1669};
1670} // end anonymous namespace
1671
1672namespace {
1673/// Find all local variable captures in the statement.
1674struct CaptureFinder : ConstStmtVisitor<CaptureFinder> {
1675 CodeGenFunction &ParentCGF;
1676 const VarDecl *ParentThis;
1677 llvm::SmallSetVector<const VarDecl *, 4> Captures;
1678 Address SEHCodeSlot = Address::invalid();
1679 CaptureFinder(CodeGenFunction &ParentCGF, const VarDecl *ParentThis)
1680 : ParentCGF(ParentCGF), ParentThis(ParentThis) {}
1681
1682 // Return true if we need to do any capturing work.
1683 bool foundCaptures() {
1684 return !Captures.empty() || SEHCodeSlot.isValid();
1685 }
1686
1687 void Visit(const Stmt *S) {
1688 // See if this is a capture, then recurse.
1689 ConstStmtVisitor<CaptureFinder>::Visit(S);
1690 for (const Stmt *Child : S->children())
1691 if (Child)
1692 Visit(Child);
1693 }
1694
1695 void VisitDeclRefExpr(const DeclRefExpr *E) {
1696 // If this is already a capture, just make sure we capture 'this'.
1697 if (E->refersToEnclosingVariableOrCapture())
1698 Captures.insert(ParentThis);
1699
1700 const auto *D = dyn_cast<VarDecl>(E->getDecl());
1701 if (D && D->isLocalVarDeclOrParm() && D->hasLocalStorage())
1702 Captures.insert(D);
1703 }
1704
1705 void VisitCXXThisExpr(const CXXThisExpr *E) {
1706 Captures.insert(ParentThis);
1707 }
1708
1709 void VisitCallExpr(const CallExpr *E) {
1710 // We only need to add parent frame allocations for these builtins in x86.
1711 if (ParentCGF.getTarget().getTriple().getArch() != llvm::Triple::x86)
1712 return;
1713
1714 unsigned ID = E->getBuiltinCallee();
1715 switch (ID) {
1716 case Builtin::BI__exception_code:
1717 case Builtin::BI_exception_code:
1718 // This is the simple case where we are the outermost finally. All we
1719 // have to do here is make sure we escape this and recover it in the
1720 // outlined handler.
1721 if (!SEHCodeSlot.isValid())
1722 SEHCodeSlot = ParentCGF.SEHCodeSlotStack.back();
1723 break;
1724 }
1725 }
1726};
1727} // end anonymous namespace
1728
1729Address CodeGenFunction::recoverAddrOfEscapedLocal(CodeGenFunction &ParentCGF,
1730 Address ParentVar,
1731 llvm::Value *ParentFP) {
1732 llvm::CallInst *RecoverCall = nullptr;
1733 CGBuilderTy Builder(*this, AllocaInsertPt);
1734 if (auto *ParentAlloca = dyn_cast<llvm::AllocaInst>(ParentVar.getPointer())) {
1735 // Mark the variable escaped if nobody else referenced it and compute the
1736 // localescape index.
1737 auto InsertPair = ParentCGF.EscapedLocals.insert(
1738 std::make_pair(ParentAlloca, ParentCGF.EscapedLocals.size()));
1739 int FrameEscapeIdx = InsertPair.first->second;
1740 // call i8* @llvm.localrecover(i8* bitcast(@parentFn), i8* %fp, i32 N)
1741 llvm::Function *FrameRecoverFn = llvm::Intrinsic::getDeclaration(
1742 &CGM.getModule(), llvm::Intrinsic::localrecover);
1743 llvm::Constant *ParentI8Fn =
1744 llvm::ConstantExpr::getBitCast(ParentCGF.CurFn, Int8PtrTy);
1745 RecoverCall = Builder.CreateCall(
1746 FrameRecoverFn, {ParentI8Fn, ParentFP,
1747 llvm::ConstantInt::get(Int32Ty, FrameEscapeIdx)});
1748
1749 } else {
1750 // If the parent didn't have an alloca, we're doing some nested outlining.
1751 // Just clone the existing localrecover call, but tweak the FP argument to
1752 // use our FP value. All other arguments are constants.
1753 auto *ParentRecover =
1754 cast<llvm::IntrinsicInst>(ParentVar.getPointer()->stripPointerCasts());
1755 assert(ParentRecover->getIntrinsicID() == llvm::Intrinsic::localrecover &&
1756 "expected alloca or localrecover in parent LocalDeclMap");
1757 RecoverCall = cast<llvm::CallInst>(ParentRecover->clone());
1758 RecoverCall->setArgOperand(1, ParentFP);
1759 RecoverCall->insertBefore(AllocaInsertPt);
1760 }
1761
1762 // Bitcast the variable, rename it, and insert it in the local decl map.
1763 llvm::Value *ChildVar =
1764 Builder.CreateBitCast(RecoverCall, ParentVar.getType());
1765 ChildVar->setName(ParentVar.getName());
1766 return Address(ChildVar, ParentVar.getAlignment());
1767}
1768
1769void CodeGenFunction::EmitCapturedLocals(CodeGenFunction &ParentCGF,
1770 const Stmt *OutlinedStmt,
1771 bool IsFilter) {
1772 // Find all captures in the Stmt.
1773 CaptureFinder Finder(ParentCGF, ParentCGF.CXXABIThisDecl);
1774 Finder.Visit(OutlinedStmt);
1775
1776 // We can exit early on x86_64 when there are no captures. We just have to
1777 // save the exception code in filters so that __exception_code() works.
1778 if (!Finder.foundCaptures() &&
1779 CGM.getTarget().getTriple().getArch() != llvm::Triple::x86) {
1780 if (IsFilter)
1781 EmitSEHExceptionCodeSave(ParentCGF, nullptr, nullptr);
1782 return;
1783 }
1784
1785 llvm::Value *EntryFP = nullptr;
1786 CGBuilderTy Builder(CGM, AllocaInsertPt);
1787 if (IsFilter && CGM.getTarget().getTriple().getArch() == llvm::Triple::x86) {
1788 // 32-bit SEH filters need to be careful about FP recovery. The end of the
1789 // EH registration is passed in as the EBP physical register. We can
1790 // recover that with llvm.frameaddress(1).
1791 EntryFP = Builder.CreateCall(
1792 CGM.getIntrinsic(llvm::Intrinsic::frameaddress, AllocaInt8PtrTy),
1793 {Builder.getInt32(1)});
1794 } else {
1795 // Otherwise, for x64 and 32-bit finally functions, the parent FP is the
1796 // second parameter.
1797 auto AI = CurFn->arg_begin();
1798 ++AI;
1799 EntryFP = &*AI;
1800 }
1801
1802 llvm::Value *ParentFP = EntryFP;
1803 if (IsFilter) {
1804 // Given whatever FP the runtime provided us in EntryFP, recover the true
1805 // frame pointer of the parent function. We only need to do this in filters,
1806 // since finally funclets recover the parent FP for us.
1807 llvm::Function *RecoverFPIntrin =
1808 CGM.getIntrinsic(llvm::Intrinsic::eh_recoverfp);
1809 llvm::Constant *ParentI8Fn =
1810 llvm::ConstantExpr::getBitCast(ParentCGF.CurFn, Int8PtrTy);
1811 ParentFP = Builder.CreateCall(RecoverFPIntrin, {ParentI8Fn, EntryFP});
1812
1813 // if the parent is a _finally, the passed-in ParentFP is the FP
1814 // of parent _finally, not Establisher's FP (FP of outermost function).
1815 // Establkisher FP is 2nd paramenter passed into parent _finally.
1816 // Fortunately, it's always saved in parent's frame. The following
1817 // code retrieves it, and escapes it so that spill instruction won't be
1818 // optimized away.
1819 if (ParentCGF.ParentCGF != nullptr) {
1820 // Locate and escape Parent's frame_pointer.addr alloca
1821 // Depending on target, should be 1st/2nd one in LocalDeclMap.
1822 // Let's just scan for ImplicitParamDecl with VoidPtrTy.
1823 llvm::AllocaInst *FramePtrAddrAlloca = nullptr;
1824 for (auto &I : ParentCGF.LocalDeclMap) {
1825 const VarDecl *D = cast<VarDecl>(I.first);
1826 if (isa<ImplicitParamDecl>(D) &&
1827 D->getType() == getContext().VoidPtrTy) {
1828 assert(D->getName().startswith("frame_pointer"));
1829 FramePtrAddrAlloca = cast<llvm::AllocaInst>(I.second.getPointer());
1830 break;
1831 }
1832 }
1833 assert(FramePtrAddrAlloca);
1834 auto InsertPair = ParentCGF.EscapedLocals.insert(
1835 std::make_pair(FramePtrAddrAlloca, ParentCGF.EscapedLocals.size()));
1836 int FrameEscapeIdx = InsertPair.first->second;
1837
1838 // an example of a filter's prolog::
1839 // %0 = call i8* @llvm.eh.recoverfp(bitcast(@"?fin$0@0@main@@"),..)
1840 // %1 = call i8* @llvm.localrecover(bitcast(@"?fin$0@0@main@@"),..)
1841 // %2 = bitcast i8* %1 to i8**
1842 // %3 = load i8*, i8* *%2, align 8
1843 // ==> %3 is the frame-pointer of outermost host function
1844 llvm::Function *FrameRecoverFn = llvm::Intrinsic::getDeclaration(
1845 &CGM.getModule(), llvm::Intrinsic::localrecover);
1846 llvm::Constant *ParentI8Fn =
1847 llvm::ConstantExpr::getBitCast(ParentCGF.CurFn, Int8PtrTy);
1848 ParentFP = Builder.CreateCall(
1849 FrameRecoverFn, {ParentI8Fn, ParentFP,
1850 llvm::ConstantInt::get(Int32Ty, FrameEscapeIdx)});
1851 ParentFP = Builder.CreateBitCast(ParentFP, CGM.VoidPtrPtrTy);
1852 ParentFP = Builder.CreateLoad(Address(ParentFP, getPointerAlign()));
1853 }
1854 }
1855
1856 // Create llvm.localrecover calls for all captures.
1857 for (const VarDecl *VD : Finder.Captures) {
1858 if (VD->getType()->isVariablyModifiedType()) {
1859 CGM.ErrorUnsupported(VD, "VLA captured by SEH");
1860 continue;
1861 }
1862 assert((isa<ImplicitParamDecl>(VD) || VD->isLocalVarDeclOrParm()) &&
1863 "captured non-local variable");
1864
1865 auto L = ParentCGF.LambdaCaptureFields.find(VD);
1866 if (L != ParentCGF.LambdaCaptureFields.end()) {
1867 LambdaCaptureFields[VD] = L->second;
1868 continue;
1869 }
1870
1871 // If this decl hasn't been declared yet, it will be declared in the
1872 // OutlinedStmt.
1873 auto I = ParentCGF.LocalDeclMap.find(VD);
1874 if (I == ParentCGF.LocalDeclMap.end())
1875 continue;
1876
1877 Address ParentVar = I->second;
1878 Address Recovered =
1879 recoverAddrOfEscapedLocal(ParentCGF, ParentVar, ParentFP);
1880 setAddrOfLocalVar(VD, Recovered);
1881
1882 if (isa<ImplicitParamDecl>(VD)) {
1883 CXXABIThisAlignment = ParentCGF.CXXABIThisAlignment;
1884 CXXThisAlignment = ParentCGF.CXXThisAlignment;
1885 CXXABIThisValue = Builder.CreateLoad(Recovered, "this");
1886 if (ParentCGF.LambdaThisCaptureField) {
1887 LambdaThisCaptureField = ParentCGF.LambdaThisCaptureField;
1888 // We are in a lambda function where "this" is captured so the
1889 // CXXThisValue need to be loaded from the lambda capture
1890 LValue ThisFieldLValue =
1891 EmitLValueForLambdaField(LambdaThisCaptureField);
1892 if (!LambdaThisCaptureField->getType()->isPointerType()) {
1893 CXXThisValue = ThisFieldLValue.getAddress(*this).getPointer();
1894 } else {
1895 CXXThisValue = EmitLoadOfLValue(ThisFieldLValue, SourceLocation())
1896 .getScalarVal();
1897 }
1898 } else {
1899 CXXThisValue = CXXABIThisValue;
1900 }
1901 }
1902 }
1903
1904 if (Finder.SEHCodeSlot.isValid()) {
1905 SEHCodeSlotStack.push_back(
1906 recoverAddrOfEscapedLocal(ParentCGF, Finder.SEHCodeSlot, ParentFP));
1907 }
1908
1909 if (IsFilter)
1910 EmitSEHExceptionCodeSave(ParentCGF, ParentFP, EntryFP);
1911}
1912
1913/// Arrange a function prototype that can be called by Windows exception
1914/// handling personalities. On Win64, the prototype looks like:
1915/// RetTy func(void *EHPtrs, void *ParentFP);
1916void CodeGenFunction::startOutlinedSEHHelper(CodeGenFunction &ParentCGF,
1917 bool IsFilter,
1918 const Stmt *OutlinedStmt) {
1919 SourceLocation StartLoc = OutlinedStmt->getBeginLoc();
1920
1921 // Get the mangled function name.
1922 SmallString<128> Name;
1923 {
1924 llvm::raw_svector_ostream OS(Name);
1925 const NamedDecl *ParentSEHFn = ParentCGF.CurSEHParent;
1926 assert(ParentSEHFn && "No CurSEHParent!");
1927 MangleContext &Mangler = CGM.getCXXABI().getMangleContext();
1928 if (IsFilter)
1929 Mangler.mangleSEHFilterExpression(ParentSEHFn, OS);
1930 else
1931 Mangler.mangleSEHFinallyBlock(ParentSEHFn, OS);
1932 }
1933
1934 FunctionArgList Args;
1935 if (CGM.getTarget().getTriple().getArch() != llvm::Triple::x86 || !IsFilter) {
1936 // All SEH finally functions take two parameters. Win64 filters take two
1937 // parameters. Win32 filters take no parameters.
1938 if (IsFilter) {
1939 Args.push_back(ImplicitParamDecl::Create(
1940 getContext(), /*DC=*/nullptr, StartLoc,
1941 &getContext().Idents.get("exception_pointers"),
1942 getContext().VoidPtrTy, ImplicitParamDecl::Other));
1943 } else {
1944 Args.push_back(ImplicitParamDecl::Create(
1945 getContext(), /*DC=*/nullptr, StartLoc,
1946 &getContext().Idents.get("abnormal_termination"),
1947 getContext().UnsignedCharTy, ImplicitParamDecl::Other));
1948 }
1949 Args.push_back(ImplicitParamDecl::Create(
1950 getContext(), /*DC=*/nullptr, StartLoc,
1951 &getContext().Idents.get("frame_pointer"), getContext().VoidPtrTy,
1952 ImplicitParamDecl::Other));
1953 }
1954
1955 QualType RetTy = IsFilter ? getContext().LongTy : getContext().VoidTy;
1956
1957 const CGFunctionInfo &FnInfo =
1958 CGM.getTypes().arrangeBuiltinFunctionDeclaration(RetTy, Args);
1959
1960 llvm::FunctionType *FnTy = CGM.getTypes().GetFunctionType(FnInfo);
1961 llvm::Function *Fn = llvm::Function::Create(
1962 FnTy, llvm::GlobalValue::InternalLinkage, Name.str(), &CGM.getModule());
1963
1964 IsOutlinedSEHHelper = true;
1965
1966 StartFunction(GlobalDecl(), RetTy, Fn, FnInfo, Args,
1967 OutlinedStmt->getBeginLoc(), OutlinedStmt->getBeginLoc());
1968 CurSEHParent = ParentCGF.CurSEHParent;
1969 CurCodeDecl = ParentCGF.CurCodeDecl;
1970
1971 CGM.SetInternalFunctionAttributes(GlobalDecl(), CurFn, FnInfo);
1972 EmitCapturedLocals(ParentCGF, OutlinedStmt, IsFilter);
1973}
1974
1975/// Create a stub filter function that will ultimately hold the code of the
1976/// filter expression. The EH preparation passes in LLVM will outline the code
1977/// from the main function body into this stub.
1978llvm::Function *
1979CodeGenFunction::GenerateSEHFilterFunction(CodeGenFunction &ParentCGF,
1980 const SEHExceptStmt &Except) {
1981 const Expr *FilterExpr = Except.getFilterExpr();
1982 startOutlinedSEHHelper(ParentCGF, true, FilterExpr);
1983
1984 // Emit the original filter expression, convert to i32, and return.
1985 llvm::Value *R = EmitScalarExpr(FilterExpr);
1986 R = Builder.CreateIntCast(R, ConvertType(getContext().LongTy),
1987 FilterExpr->getType()->isSignedIntegerType());
1988 Builder.CreateStore(R, ReturnValue);
1989
1990 FinishFunction(FilterExpr->getEndLoc());
1991
1992 return CurFn;
1993}
1994
1995llvm::Function *
1996CodeGenFunction::GenerateSEHFinallyFunction(CodeGenFunction &ParentCGF,
1997 const SEHFinallyStmt &Finally) {
1998 const Stmt *FinallyBlock = Finally.getBlock();
1999 startOutlinedSEHHelper(ParentCGF, false, FinallyBlock);
2000
2001 // Emit the original filter expression, convert to i32, and return.
2002 EmitStmt(FinallyBlock);
2003
2004 FinishFunction(FinallyBlock->getEndLoc());
2005
2006 return CurFn;
2007}
2008
2009void CodeGenFunction::EmitSEHExceptionCodeSave(CodeGenFunction &ParentCGF,
2010 llvm::Value *ParentFP,
2011 llvm::Value *EntryFP) {
2012 // Get the pointer to the EXCEPTION_POINTERS struct. This is returned by the
2013 // __exception_info intrinsic.
2014 if (CGM.getTarget().getTriple().getArch() != llvm::Triple::x86) {
2015 // On Win64, the info is passed as the first parameter to the filter.
2016 SEHInfo = &*CurFn->arg_begin();
2017 SEHCodeSlotStack.push_back(
2018 CreateMemTemp(getContext().IntTy, "__exception_code"));
2019 } else {
2020 // On Win32, the EBP on entry to the filter points to the end of an
2021 // exception registration object. It contains 6 32-bit fields, and the info
2022 // pointer is stored in the second field. So, GEP 20 bytes backwards and
2023 // load the pointer.
2024 SEHInfo = Builder.CreateConstInBoundsGEP1_32(Int8Ty, EntryFP, -20);
2025 SEHInfo = Builder.CreateBitCast(SEHInfo, Int8PtrTy->getPointerTo());
2026 SEHInfo = Builder.CreateAlignedLoad(Int8PtrTy, SEHInfo, getPointerAlign());
2027 SEHCodeSlotStack.push_back(recoverAddrOfEscapedLocal(
2028 ParentCGF, ParentCGF.SEHCodeSlotStack.back(), ParentFP));
2029 }
2030
2031 // Save the exception code in the exception slot to unify exception access in
2032 // the filter function and the landing pad.
2033 // struct EXCEPTION_POINTERS {
2034 // EXCEPTION_RECORD *ExceptionRecord;
2035 // CONTEXT *ContextRecord;
2036 // };
2037 // int exceptioncode = exception_pointers->ExceptionRecord->ExceptionCode;
2038 llvm::Type *RecordTy = CGM.Int32Ty->getPointerTo();
2039 llvm::Type *PtrsTy = llvm::StructType::get(RecordTy, CGM.VoidPtrTy);
2040 llvm::Value *Ptrs = Builder.CreateBitCast(SEHInfo, PtrsTy->getPointerTo());
2041 llvm::Value *Rec = Builder.CreateStructGEP(PtrsTy, Ptrs, 0);
2042 Rec = Builder.CreateAlignedLoad(RecordTy, Rec, getPointerAlign());
2043 llvm::Value *Code = Builder.CreateAlignedLoad(Int32Ty, Rec, getIntAlign());
2044 assert(!SEHCodeSlotStack.empty() && "emitting EH code outside of __except");
2045 Builder.CreateStore(Code, SEHCodeSlotStack.back());
2046}
2047
2048llvm::Value *CodeGenFunction::EmitSEHExceptionInfo() {
2049 // Sema should diagnose calling this builtin outside of a filter context, but
2050 // don't crash if we screw up.
2051 if (!SEHInfo)
2052 return llvm::UndefValue::get(Int8PtrTy);
2053 assert(SEHInfo->getType() == Int8PtrTy);
2054 return SEHInfo;
2055}
2056
2057llvm::Value *CodeGenFunction::EmitSEHExceptionCode() {
2058 assert(!SEHCodeSlotStack.empty() && "emitting EH code outside of __except");
2059 return Builder.CreateLoad(SEHCodeSlotStack.back());
2060}
2061
2062llvm::Value *CodeGenFunction::EmitSEHAbnormalTermination() {
2063 // Abnormal termination is just the first parameter to the outlined finally
2064 // helper.
2065 auto AI = CurFn->arg_begin();
2066 return Builder.CreateZExt(&*AI, Int32Ty);
2067}
2068
2069void CodeGenFunction::pushSEHCleanup(CleanupKind Kind,
2070 llvm::Function *FinallyFunc) {
2071 EHStack.pushCleanup<PerformSEHFinally>(Kind, FinallyFunc);
2072}
2073
2074void CodeGenFunction::EnterSEHTryStmt(const SEHTryStmt &S) {
2075 CodeGenFunction HelperCGF(CGM, /*suppressNewContext=*/true);
2076 HelperCGF.ParentCGF = this;
2077 if (const SEHFinallyStmt *Finally = S.getFinallyHandler()) {
2078 // Outline the finally block.
2079 llvm::Function *FinallyFunc =
2080 HelperCGF.GenerateSEHFinallyFunction(*this, *Finally);
2081
2082 // Push a cleanup for __finally blocks.
2083 EHStack.pushCleanup<PerformSEHFinally>(NormalAndEHCleanup, FinallyFunc);
2084 return;
2085 }
2086
2087 // Otherwise, we must have an __except block.
2088 const SEHExceptStmt *Except = S.getExceptHandler();
2089 assert(Except);
2090 EHCatchScope *CatchScope = EHStack.pushCatch(1);
2091 SEHCodeSlotStack.push_back(
2092 CreateMemTemp(getContext().IntTy, "__exception_code"));
2093
2094 // If the filter is known to evaluate to 1, then we can use the clause
2095 // "catch i8* null". We can't do this on x86 because the filter has to save
2096 // the exception code.
2097 llvm::Constant *C =
2098 ConstantEmitter(*this).tryEmitAbstract(Except->getFilterExpr(),
2099 getContext().IntTy);
2100 if (CGM.getTarget().getTriple().getArch() != llvm::Triple::x86 && C &&
2101 C->isOneValue()) {
2102 CatchScope->setCatchAllHandler(0, createBasicBlock("__except"));
2103 return;
2104 }
2105
2106 // In general, we have to emit an outlined filter function. Use the function
2107 // in place of the RTTI typeinfo global that C++ EH uses.
2108 llvm::Function *FilterFunc =
2109 HelperCGF.GenerateSEHFilterFunction(*this, *Except);
2110 llvm::Constant *OpaqueFunc =
2111 llvm::ConstantExpr::getBitCast(FilterFunc, Int8PtrTy);
2112 CatchScope->setHandler(0, OpaqueFunc, createBasicBlock("__except.ret"));
2113}
2114
2115void CodeGenFunction::ExitSEHTryStmt(const SEHTryStmt &S) {
2116 // Just pop the cleanup if it's a __finally block.
2117 if (S.getFinallyHandler()) {
2118 PopCleanupBlock();
2119 return;
2120 }
2121
2122 // Otherwise, we must have an __except block.
2123 const SEHExceptStmt *Except = S.getExceptHandler();
2124 assert(Except && "__try must have __finally xor __except");
2125 EHCatchScope &CatchScope = cast<EHCatchScope>(*EHStack.begin());
2126
2127 // Don't emit the __except block if the __try block lacked invokes.
2128 // TODO: Model unwind edges from instructions, either with iload / istore or
2129 // a try body function.
2130 if (!CatchScope.hasEHBranches()) {
2131 CatchScope.clearHandlerBlocks();
2132 EHStack.popCatch();
2133 SEHCodeSlotStack.pop_back();
2134 return;
2135 }
2136
2137 // The fall-through block.
2138 llvm::BasicBlock *ContBB = createBasicBlock("__try.cont");
2139
2140 // We just emitted the body of the __try; jump to the continue block.
2141 if (HaveInsertPoint())
2142 Builder.CreateBr(ContBB);
2143
2144 // Check if our filter function returned true.
2145 emitCatchDispatchBlock(*this, CatchScope);
2146
2147 // Grab the block before we pop the handler.
2148 llvm::BasicBlock *CatchPadBB = CatchScope.getHandler(0).Block;
2149 EHStack.popCatch();
2150
2151 EmitBlockAfterUses(CatchPadBB);
2152
2153 // __except blocks don't get outlined into funclets, so immediately do a
2154 // catchret.
2155 llvm::CatchPadInst *CPI =
2156 cast<llvm::CatchPadInst>(CatchPadBB->getFirstNonPHI());
2157 llvm::BasicBlock *ExceptBB = createBasicBlock("__except");
2158 Builder.CreateCatchRet(CPI, ExceptBB);
2159 EmitBlock(ExceptBB);
2160
2161 // On Win64, the exception code is returned in EAX. Copy it into the slot.
2162 if (CGM.getTarget().getTriple().getArch() != llvm::Triple::x86) {
2163 llvm::Function *SEHCodeIntrin =
2164 CGM.getIntrinsic(llvm::Intrinsic::eh_exceptioncode);
2165 llvm::Value *Code = Builder.CreateCall(SEHCodeIntrin, {CPI});
2166 Builder.CreateStore(Code, SEHCodeSlotStack.back());
2167 }
2168
2169 // Emit the __except body.
2170 EmitStmt(Except->getBlock());
2171
2172 // End the lifetime of the exception code.
2173 SEHCodeSlotStack.pop_back();
2174
2175 if (HaveInsertPoint())
2176 Builder.CreateBr(ContBB);
2177
2178 EmitBlock(ContBB);
2179}
2180
2181void CodeGenFunction::EmitSEHLeaveStmt(const SEHLeaveStmt &S) {
2182 // If this code is reachable then emit a stop point (if generating
2183 // debug info). We have to do this ourselves because we are on the
2184 // "simple" statement path.
2185 if (HaveInsertPoint())
2186 EmitStopPoint(&S);
2187
2188 // This must be a __leave from a __finally block, which we warn on and is UB.
2189 // Just emit unreachable.
2190 if (!isSEHTryScope()) {
2191 Builder.CreateUnreachable();
2192 Builder.ClearInsertionPoint();
2193 return;
2194 }
2195
2196 EmitBranchThroughCleanup(*SEHTryEpilogueStack.back());
2197}
2198