1 //===-- X86WinEHState - Insert EH state updates for win32 exceptions ------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // All functions using an MSVC EH personality use an explicitly updated state
11 // number stored in an exception registration stack object. The registration
12 // object is linked into a thread-local chain of registrations stored at fs:00.
13 // This pass adds the registration object and EH state updates.
15 //===----------------------------------------------------------------------===//
18 #include "llvm/ADT/PostOrderIterator.h"
19 #include "llvm/Analysis/CFG.h"
20 #include "llvm/Analysis/EHPersonalities.h"
21 #include "llvm/CodeGen/MachineModuleInfo.h"
22 #include "llvm/CodeGen/WinEHFuncInfo.h"
23 #include "llvm/IR/CallSite.h"
24 #include "llvm/IR/Function.h"
25 #include "llvm/IR/IRBuilder.h"
26 #include "llvm/IR/Instructions.h"
27 #include "llvm/IR/IntrinsicInst.h"
28 #include "llvm/IR/Module.h"
29 #include "llvm/Pass.h"
30 #include "llvm/Support/Debug.h"
35 #define DEBUG_TYPE "winehstate"
38 void initializeWinEHStatePassPass(PassRegistry &);
42 const int OverdefinedState = INT_MIN;
44 class WinEHStatePass : public FunctionPass {
46 static char ID; // Pass identification, replacement for typeid.
48 WinEHStatePass() : FunctionPass(ID) {
49 initializeWinEHStatePassPass(*PassRegistry::getPassRegistry());
52 bool runOnFunction(Function &Fn) override;
54 bool doInitialization(Module &M) override;
56 bool doFinalization(Module &M) override;
58 void getAnalysisUsage(AnalysisUsage &AU) const override;
60 StringRef getPassName() const override {
61 return "Windows 32-bit x86 EH state insertion";
65 void emitExceptionRegistrationRecord(Function *F);
67 void linkExceptionRegistration(IRBuilder<> &Builder, Function *Handler);
68 void unlinkExceptionRegistration(IRBuilder<> &Builder);
69 void addStateStores(Function &F, WinEHFuncInfo &FuncInfo);
70 void insertStateNumberStore(Instruction *IP, int State);
72 Value *emitEHLSDA(IRBuilder<> &Builder, Function *F);
74 Function *generateLSDAInEAXThunk(Function *ParentFunc);
76 bool isStateStoreNeeded(EHPersonality Personality, CallSite CS);
77 void rewriteSetJmpCallSite(IRBuilder<> &Builder, Function &F, CallSite CS,
79 int getBaseStateForBB(DenseMap<BasicBlock *, ColorVector> &BlockColors,
80 WinEHFuncInfo &FuncInfo, BasicBlock *BB);
81 int getStateForCallSite(DenseMap<BasicBlock *, ColorVector> &BlockColors,
82 WinEHFuncInfo &FuncInfo, CallSite CS);
84 // Module-level type getters.
85 Type *getEHLinkRegistrationType();
86 Type *getSEHRegistrationType();
87 Type *getCXXEHRegistrationType();
90 Module *TheModule = nullptr;
91 StructType *EHLinkRegistrationTy = nullptr;
92 StructType *CXXEHRegistrationTy = nullptr;
93 StructType *SEHRegistrationTy = nullptr;
94 Constant *SetJmp3 = nullptr;
95 Constant *CxxLongjmpUnwind = nullptr;
98 EHPersonality Personality = EHPersonality::Unknown;
99 Function *PersonalityFn = nullptr;
100 bool UseStackGuard = false;
102 Constant *SehLongjmpUnwind = nullptr;
103 Constant *Cookie = nullptr;
105 /// The stack allocation containing all EH data, including the link in the
106 /// fs:00 chain and the current state.
107 AllocaInst *RegNode = nullptr;
109 // The allocation containing the EH security guard.
110 AllocaInst *EHGuardNode = nullptr;
112 /// The index of the state field of RegNode.
113 int StateFieldIndex = ~0U;
115 /// The linked list node subobject inside of RegNode.
116 Value *Link = nullptr;
120 FunctionPass *llvm::createX86WinEHStatePass() { return new WinEHStatePass(); }
122 char WinEHStatePass::ID = 0;
124 INITIALIZE_PASS(WinEHStatePass, "x86-winehstate",
125 "Insert stores for EH state numbers", false, false)
127 bool WinEHStatePass::doInitialization(Module &M) {
132 bool WinEHStatePass::doFinalization(Module &M) {
133 assert(TheModule == &M);
135 EHLinkRegistrationTy = nullptr;
136 CXXEHRegistrationTy = nullptr;
137 SEHRegistrationTy = nullptr;
139 CxxLongjmpUnwind = nullptr;
140 SehLongjmpUnwind = nullptr;
145 void WinEHStatePass::getAnalysisUsage(AnalysisUsage &AU) const {
146 // This pass should only insert a stack allocation, memory accesses, and
148 AU.setPreservesCFG();
151 bool WinEHStatePass::runOnFunction(Function &F) {
152 // Check the personality. Do nothing if this personality doesn't use funclets.
153 if (!F.hasPersonalityFn())
156 dyn_cast<Function>(F.getPersonalityFn()->stripPointerCasts());
159 Personality = classifyEHPersonality(PersonalityFn);
160 if (!isFuncletEHPersonality(Personality))
163 // Skip this function if there are no EH pads and we aren't using IR-level
165 bool HasPads = false;
166 for (BasicBlock &BB : F) {
175 Type *Int8PtrType = Type::getInt8PtrTy(TheModule->getContext());
176 SetJmp3 = TheModule->getOrInsertFunction(
177 "_setjmp3", FunctionType::get(
178 Type::getInt32Ty(TheModule->getContext()),
179 {Int8PtrType, Type::getInt32Ty(TheModule->getContext())},
182 // Disable frame pointer elimination in this function.
183 // FIXME: Do the nested handlers need to keep the parent ebp in ebp, or can we
184 // use an arbitrary register?
185 F.addFnAttr("no-frame-pointer-elim", "true");
187 emitExceptionRegistrationRecord(&F);
189 // The state numbers calculated here in IR must agree with what we calculate
190 // later on for the MachineFunction. In particular, if an IR pass deletes an
191 // unreachable EH pad after this point before machine CFG construction, we
192 // will be in trouble. If this assumption is ever broken, we should turn the
193 // numbers into an immutable analysis pass.
194 WinEHFuncInfo FuncInfo;
195 addStateStores(F, FuncInfo);
197 // Reset per-function state.
198 PersonalityFn = nullptr;
199 Personality = EHPersonality::Unknown;
200 UseStackGuard = false;
202 EHGuardNode = nullptr;
207 /// Get the common EH registration subobject:
208 /// typedef _EXCEPTION_DISPOSITION (*PEXCEPTION_ROUTINE)(
209 /// _EXCEPTION_RECORD *, void *, _CONTEXT *, void *);
210 /// struct EHRegistrationNode {
211 /// EHRegistrationNode *Next;
212 /// PEXCEPTION_ROUTINE Handler;
214 Type *WinEHStatePass::getEHLinkRegistrationType() {
215 if (EHLinkRegistrationTy)
216 return EHLinkRegistrationTy;
217 LLVMContext &Context = TheModule->getContext();
218 EHLinkRegistrationTy = StructType::create(Context, "EHRegistrationNode");
220 EHLinkRegistrationTy->getPointerTo(0), // EHRegistrationNode *Next
221 Type::getInt8PtrTy(Context) // EXCEPTION_DISPOSITION (*Handler)(...)
223 EHLinkRegistrationTy->setBody(FieldTys, false);
224 return EHLinkRegistrationTy;
227 /// The __CxxFrameHandler3 registration node:
228 /// struct CXXExceptionRegistration {
230 /// EHRegistrationNode SubRecord;
231 /// int32_t TryLevel;
233 Type *WinEHStatePass::getCXXEHRegistrationType() {
234 if (CXXEHRegistrationTy)
235 return CXXEHRegistrationTy;
236 LLVMContext &Context = TheModule->getContext();
238 Type::getInt8PtrTy(Context), // void *SavedESP
239 getEHLinkRegistrationType(), // EHRegistrationNode SubRecord
240 Type::getInt32Ty(Context) // int32_t TryLevel
242 CXXEHRegistrationTy =
243 StructType::create(FieldTys, "CXXExceptionRegistration");
244 return CXXEHRegistrationTy;
247 /// The _except_handler3/4 registration node:
248 /// struct EH4ExceptionRegistration {
250 /// _EXCEPTION_POINTERS *ExceptionPointers;
251 /// EHRegistrationNode SubRecord;
252 /// int32_t EncodedScopeTable;
253 /// int32_t TryLevel;
255 Type *WinEHStatePass::getSEHRegistrationType() {
256 if (SEHRegistrationTy)
257 return SEHRegistrationTy;
258 LLVMContext &Context = TheModule->getContext();
260 Type::getInt8PtrTy(Context), // void *SavedESP
261 Type::getInt8PtrTy(Context), // void *ExceptionPointers
262 getEHLinkRegistrationType(), // EHRegistrationNode SubRecord
263 Type::getInt32Ty(Context), // int32_t EncodedScopeTable
264 Type::getInt32Ty(Context) // int32_t TryLevel
266 SEHRegistrationTy = StructType::create(FieldTys, "SEHExceptionRegistration");
267 return SEHRegistrationTy;
270 // Emit an exception registration record. These are stack allocations with the
271 // common subobject of two pointers: the previous registration record (the old
272 // fs:00) and the personality function for the current frame. The data before
273 // and after that is personality function specific.
274 void WinEHStatePass::emitExceptionRegistrationRecord(Function *F) {
275 assert(Personality == EHPersonality::MSVC_CXX ||
276 Personality == EHPersonality::MSVC_X86SEH);
278 // Struct type of RegNode. Used for GEPing.
281 IRBuilder<> Builder(&F->getEntryBlock(), F->getEntryBlock().begin());
282 Type *Int8PtrType = Builder.getInt8PtrTy();
283 Type *Int32Ty = Builder.getInt32Ty();
284 Type *VoidTy = Builder.getVoidTy();
286 if (Personality == EHPersonality::MSVC_CXX) {
287 RegNodeTy = getCXXEHRegistrationType();
288 RegNode = Builder.CreateAlloca(RegNodeTy);
289 // SavedESP = llvm.stacksave()
290 Value *SP = Builder.CreateCall(
291 Intrinsic::getDeclaration(TheModule, Intrinsic::stacksave), {});
292 Builder.CreateStore(SP, Builder.CreateStructGEP(RegNodeTy, RegNode, 0));
295 ParentBaseState = -1;
296 insertStateNumberStore(&*Builder.GetInsertPoint(), ParentBaseState);
297 // Handler = __ehhandler$F
298 Function *Trampoline = generateLSDAInEAXThunk(F);
299 Link = Builder.CreateStructGEP(RegNodeTy, RegNode, 1);
300 linkExceptionRegistration(Builder, Trampoline);
302 CxxLongjmpUnwind = TheModule->getOrInsertFunction(
303 "__CxxLongjmpUnwind",
304 FunctionType::get(VoidTy, Int8PtrType, /*isVarArg=*/false));
305 cast<Function>(CxxLongjmpUnwind->stripPointerCasts())
306 ->setCallingConv(CallingConv::X86_StdCall);
307 } else if (Personality == EHPersonality::MSVC_X86SEH) {
308 // If _except_handler4 is in use, some additional guard checks and prologue
309 // stuff is required.
310 StringRef PersonalityName = PersonalityFn->getName();
311 UseStackGuard = (PersonalityName == "_except_handler4");
313 // Allocate local structures.
314 RegNodeTy = getSEHRegistrationType();
315 RegNode = Builder.CreateAlloca(RegNodeTy);
317 EHGuardNode = Builder.CreateAlloca(Int32Ty);
319 // SavedESP = llvm.stacksave()
320 Value *SP = Builder.CreateCall(
321 Intrinsic::getDeclaration(TheModule, Intrinsic::stacksave), {});
322 Builder.CreateStore(SP, Builder.CreateStructGEP(RegNodeTy, RegNode, 0));
323 // TryLevel = -2 / -1
325 ParentBaseState = UseStackGuard ? -2 : -1;
326 insertStateNumberStore(&*Builder.GetInsertPoint(), ParentBaseState);
327 // ScopeTable = llvm.x86.seh.lsda(F)
328 Value *LSDA = emitEHLSDA(Builder, F);
329 LSDA = Builder.CreatePtrToInt(LSDA, Int32Ty);
330 // If using _except_handler4, xor the address of the table with
331 // __security_cookie.
333 Cookie = TheModule->getOrInsertGlobal("__security_cookie", Int32Ty);
334 Value *Val = Builder.CreateLoad(Int32Ty, Cookie, "cookie");
335 LSDA = Builder.CreateXor(LSDA, Val);
337 Builder.CreateStore(LSDA, Builder.CreateStructGEP(RegNodeTy, RegNode, 3));
339 // If using _except_handler4, the EHGuard contains: FramePtr xor Cookie.
341 Value *Val = Builder.CreateLoad(Int32Ty, Cookie);
342 Value *FrameAddr = Builder.CreateCall(
343 Intrinsic::getDeclaration(TheModule, Intrinsic::frameaddress),
344 Builder.getInt32(0), "frameaddr");
345 Value *FrameAddrI32 = Builder.CreatePtrToInt(FrameAddr, Int32Ty);
346 FrameAddrI32 = Builder.CreateXor(FrameAddrI32, Val);
347 Builder.CreateStore(FrameAddrI32, EHGuardNode);
350 // Register the exception handler.
351 Link = Builder.CreateStructGEP(RegNodeTy, RegNode, 2);
352 linkExceptionRegistration(Builder, PersonalityFn);
354 SehLongjmpUnwind = TheModule->getOrInsertFunction(
355 UseStackGuard ? "_seh_longjmp_unwind4" : "_seh_longjmp_unwind",
356 FunctionType::get(Type::getVoidTy(TheModule->getContext()), Int8PtrType,
357 /*isVarArg=*/false));
358 cast<Function>(SehLongjmpUnwind->stripPointerCasts())
359 ->setCallingConv(CallingConv::X86_StdCall);
361 llvm_unreachable("unexpected personality function");
364 // Insert an unlink before all returns.
365 for (BasicBlock &BB : *F) {
366 TerminatorInst *T = BB.getTerminator();
367 if (!isa<ReturnInst>(T))
369 Builder.SetInsertPoint(T);
370 unlinkExceptionRegistration(Builder);
374 Value *WinEHStatePass::emitEHLSDA(IRBuilder<> &Builder, Function *F) {
375 Value *FI8 = Builder.CreateBitCast(F, Type::getInt8PtrTy(F->getContext()));
376 return Builder.CreateCall(
377 Intrinsic::getDeclaration(TheModule, Intrinsic::x86_seh_lsda), FI8);
380 /// Generate a thunk that puts the LSDA of ParentFunc in EAX and then calls
381 /// PersonalityFn, forwarding the parameters passed to PEXCEPTION_ROUTINE:
382 /// typedef _EXCEPTION_DISPOSITION (*PEXCEPTION_ROUTINE)(
383 /// _EXCEPTION_RECORD *, void *, _CONTEXT *, void *);
384 /// We essentially want this code:
386 /// jmpl ___CxxFrameHandler3
387 Function *WinEHStatePass::generateLSDAInEAXThunk(Function *ParentFunc) {
388 LLVMContext &Context = ParentFunc->getContext();
389 Type *Int32Ty = Type::getInt32Ty(Context);
390 Type *Int8PtrType = Type::getInt8PtrTy(Context);
391 Type *ArgTys[5] = {Int8PtrType, Int8PtrType, Int8PtrType, Int8PtrType,
393 FunctionType *TrampolineTy =
394 FunctionType::get(Int32Ty, makeArrayRef(&ArgTys[0], 4),
396 FunctionType *TargetFuncTy =
397 FunctionType::get(Int32Ty, makeArrayRef(&ArgTys[0], 5),
399 Function *Trampoline =
400 Function::Create(TrampolineTy, GlobalValue::InternalLinkage,
401 Twine("__ehhandler$") + GlobalValue::dropLLVMManglingEscape(
402 ParentFunc->getName()),
404 BasicBlock *EntryBB = BasicBlock::Create(Context, "entry", Trampoline);
405 IRBuilder<> Builder(EntryBB);
406 Value *LSDA = emitEHLSDA(Builder, ParentFunc);
407 Value *CastPersonality =
408 Builder.CreateBitCast(PersonalityFn, TargetFuncTy->getPointerTo());
409 auto AI = Trampoline->arg_begin();
410 Value *Args[5] = {LSDA, &*AI++, &*AI++, &*AI++, &*AI++};
411 CallInst *Call = Builder.CreateCall(CastPersonality, Args);
412 // Can't use musttail due to prototype mismatch, but we can use tail.
413 Call->setTailCall(true);
414 // Set inreg so we pass it in EAX.
415 Call->addParamAttr(0, Attribute::InReg);
416 Builder.CreateRet(Call);
420 void WinEHStatePass::linkExceptionRegistration(IRBuilder<> &Builder,
422 // Emit the .safeseh directive for this function.
423 Handler->addFnAttr("safeseh");
425 Type *LinkTy = getEHLinkRegistrationType();
427 Value *HandlerI8 = Builder.CreateBitCast(Handler, Builder.getInt8PtrTy());
428 Builder.CreateStore(HandlerI8, Builder.CreateStructGEP(LinkTy, Link, 1));
431 Constant::getNullValue(LinkTy->getPointerTo()->getPointerTo(257));
432 Value *Next = Builder.CreateLoad(FSZero);
433 Builder.CreateStore(Next, Builder.CreateStructGEP(LinkTy, Link, 0));
435 Builder.CreateStore(Link, FSZero);
438 void WinEHStatePass::unlinkExceptionRegistration(IRBuilder<> &Builder) {
439 // Clone Link into the current BB for better address mode folding.
440 if (auto *GEP = dyn_cast<GetElementPtrInst>(Link)) {
441 GEP = cast<GetElementPtrInst>(GEP->clone());
445 Type *LinkTy = getEHLinkRegistrationType();
446 // [fs:00] = Link->Next
448 Builder.CreateLoad(Builder.CreateStructGEP(LinkTy, Link, 0));
450 Constant::getNullValue(LinkTy->getPointerTo()->getPointerTo(257));
451 Builder.CreateStore(Next, FSZero);
454 // Calls to setjmp(p) are lowered to _setjmp3(p, 0) by the frontend.
455 // The idea behind _setjmp3 is that it takes an optional number of personality
456 // specific parameters to indicate how to restore the personality-specific frame
457 // state when longjmp is initiated. Typically, the current TryLevel is saved.
458 void WinEHStatePass::rewriteSetJmpCallSite(IRBuilder<> &Builder, Function &F,
459 CallSite CS, Value *State) {
460 // Don't rewrite calls with a weird number of arguments.
461 if (CS.getNumArgOperands() != 2)
464 Instruction *Inst = CS.getInstruction();
466 SmallVector<OperandBundleDef, 1> OpBundles;
467 CS.getOperandBundlesAsDefs(OpBundles);
469 SmallVector<Value *, 3> OptionalArgs;
470 if (Personality == EHPersonality::MSVC_CXX) {
471 OptionalArgs.push_back(CxxLongjmpUnwind);
472 OptionalArgs.push_back(State);
473 OptionalArgs.push_back(emitEHLSDA(Builder, &F));
474 } else if (Personality == EHPersonality::MSVC_X86SEH) {
475 OptionalArgs.push_back(SehLongjmpUnwind);
476 OptionalArgs.push_back(State);
478 OptionalArgs.push_back(Cookie);
480 llvm_unreachable("unhandled personality!");
483 SmallVector<Value *, 5> Args;
485 Builder.CreateBitCast(CS.getArgOperand(0), Builder.getInt8PtrTy()));
486 Args.push_back(Builder.getInt32(OptionalArgs.size()));
487 Args.append(OptionalArgs.begin(), OptionalArgs.end());
491 auto *CI = cast<CallInst>(Inst);
492 CallInst *NewCI = Builder.CreateCall(SetJmp3, Args, OpBundles);
493 NewCI->setTailCallKind(CI->getTailCallKind());
496 auto *II = cast<InvokeInst>(Inst);
497 NewCS = Builder.CreateInvoke(
498 SetJmp3, II->getNormalDest(), II->getUnwindDest(), Args, OpBundles);
500 NewCS.setCallingConv(CS.getCallingConv());
501 NewCS.setAttributes(CS.getAttributes());
502 NewCS->setDebugLoc(CS->getDebugLoc());
504 Instruction *NewInst = NewCS.getInstruction();
505 NewInst->takeName(Inst);
506 Inst->replaceAllUsesWith(NewInst);
507 Inst->eraseFromParent();
510 // Figure out what state we should assign calls in this block.
511 int WinEHStatePass::getBaseStateForBB(
512 DenseMap<BasicBlock *, ColorVector> &BlockColors, WinEHFuncInfo &FuncInfo,
514 int BaseState = ParentBaseState;
515 auto &BBColors = BlockColors[BB];
517 assert(BBColors.size() == 1 && "multi-color BB not removed by preparation");
518 BasicBlock *FuncletEntryBB = BBColors.front();
519 if (auto *FuncletPad =
520 dyn_cast<FuncletPadInst>(FuncletEntryBB->getFirstNonPHI())) {
521 auto BaseStateI = FuncInfo.FuncletBaseStateMap.find(FuncletPad);
522 if (BaseStateI != FuncInfo.FuncletBaseStateMap.end())
523 BaseState = BaseStateI->second;
529 // Calculate the state a call-site is in.
530 int WinEHStatePass::getStateForCallSite(
531 DenseMap<BasicBlock *, ColorVector> &BlockColors, WinEHFuncInfo &FuncInfo,
533 if (auto *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
534 // Look up the state number of the EH pad this unwinds to.
535 assert(FuncInfo.InvokeStateMap.count(II) && "invoke has no state!");
536 return FuncInfo.InvokeStateMap[II];
538 // Possibly throwing call instructions have no actions to take after
539 // an unwind. Ensure they are in the -1 state.
540 return getBaseStateForBB(BlockColors, FuncInfo, CS.getParent());
543 // Calculate the intersection of all the FinalStates for a BasicBlock's
545 static int getPredState(DenseMap<BasicBlock *, int> &FinalStates, Function &F,
546 int ParentBaseState, BasicBlock *BB) {
547 // The entry block has no predecessors but we know that the prologue always
548 // sets us up with a fixed state.
549 if (&F.getEntryBlock() == BB)
550 return ParentBaseState;
552 // This is an EH Pad, conservatively report this basic block as overdefined.
554 return OverdefinedState;
556 int CommonState = OverdefinedState;
557 for (BasicBlock *PredBB : predecessors(BB)) {
558 // We didn't manage to get a state for one of these predecessors,
559 // conservatively report this basic block as overdefined.
560 auto PredEndState = FinalStates.find(PredBB);
561 if (PredEndState == FinalStates.end())
562 return OverdefinedState;
564 // This code is reachable via exceptional control flow,
565 // conservatively report this basic block as overdefined.
566 if (isa<CatchReturnInst>(PredBB->getTerminator()))
567 return OverdefinedState;
569 int PredState = PredEndState->second;
570 assert(PredState != OverdefinedState &&
571 "overdefined BBs shouldn't be in FinalStates");
572 if (CommonState == OverdefinedState)
573 CommonState = PredState;
575 // At least two predecessors have different FinalStates,
576 // conservatively report this basic block as overdefined.
577 if (CommonState != PredState)
578 return OverdefinedState;
584 // Calculate the intersection of all the InitialStates for a BasicBlock's
586 static int getSuccState(DenseMap<BasicBlock *, int> &InitialStates, Function &F,
587 int ParentBaseState, BasicBlock *BB) {
588 // This block rejoins normal control flow,
589 // conservatively report this basic block as overdefined.
590 if (isa<CatchReturnInst>(BB->getTerminator()))
591 return OverdefinedState;
593 int CommonState = OverdefinedState;
594 for (BasicBlock *SuccBB : successors(BB)) {
595 // We didn't manage to get a state for one of these predecessors,
596 // conservatively report this basic block as overdefined.
597 auto SuccStartState = InitialStates.find(SuccBB);
598 if (SuccStartState == InitialStates.end())
599 return OverdefinedState;
601 // This is an EH Pad, conservatively report this basic block as overdefined.
602 if (SuccBB->isEHPad())
603 return OverdefinedState;
605 int SuccState = SuccStartState->second;
606 assert(SuccState != OverdefinedState &&
607 "overdefined BBs shouldn't be in FinalStates");
608 if (CommonState == OverdefinedState)
609 CommonState = SuccState;
611 // At least two successors have different InitialStates,
612 // conservatively report this basic block as overdefined.
613 if (CommonState != SuccState)
614 return OverdefinedState;
620 bool WinEHStatePass::isStateStoreNeeded(EHPersonality Personality,
625 // If the function touches memory, it needs a state store.
626 if (isAsynchronousEHPersonality(Personality))
627 return !CS.doesNotAccessMemory();
629 // If the function throws, it needs a state store.
630 return !CS.doesNotThrow();
633 void WinEHStatePass::addStateStores(Function &F, WinEHFuncInfo &FuncInfo) {
634 // Mark the registration node. The backend needs to know which alloca it is so
635 // that it can recover the original frame pointer.
636 IRBuilder<> Builder(RegNode->getNextNode());
637 Value *RegNodeI8 = Builder.CreateBitCast(RegNode, Builder.getInt8PtrTy());
639 Intrinsic::getDeclaration(TheModule, Intrinsic::x86_seh_ehregnode),
643 IRBuilder<> Builder(EHGuardNode->getNextNode());
644 Value *EHGuardNodeI8 =
645 Builder.CreateBitCast(EHGuardNode, Builder.getInt8PtrTy());
647 Intrinsic::getDeclaration(TheModule, Intrinsic::x86_seh_ehguard),
651 // Calculate state numbers.
652 if (isAsynchronousEHPersonality(Personality))
653 calculateSEHStateNumbers(&F, FuncInfo);
655 calculateWinCXXEHStateNumbers(&F, FuncInfo);
657 // Iterate all the instructions and emit state number stores.
658 DenseMap<BasicBlock *, ColorVector> BlockColors = colorEHFunclets(F);
659 ReversePostOrderTraversal<Function *> RPOT(&F);
661 // InitialStates yields the state of the first call-site for a BasicBlock.
662 DenseMap<BasicBlock *, int> InitialStates;
663 // FinalStates yields the state of the last call-site for a BasicBlock.
664 DenseMap<BasicBlock *, int> FinalStates;
665 // Worklist used to revisit BasicBlocks with indeterminate
666 // Initial/Final-States.
667 std::deque<BasicBlock *> Worklist;
668 // Fill in InitialStates and FinalStates for BasicBlocks with call-sites.
669 for (BasicBlock *BB : RPOT) {
670 int InitialState = OverdefinedState;
672 if (&F.getEntryBlock() == BB)
673 InitialState = FinalState = ParentBaseState;
674 for (Instruction &I : *BB) {
676 if (!isStateStoreNeeded(Personality, CS))
679 int State = getStateForCallSite(BlockColors, FuncInfo, CS);
680 if (InitialState == OverdefinedState)
681 InitialState = State;
684 // No call-sites in this basic block? That's OK, we will come back to these
686 if (InitialState == OverdefinedState) {
687 Worklist.push_back(BB);
690 DEBUG(dbgs() << "X86WinEHState: " << BB->getName()
691 << " InitialState=" << InitialState << '\n');
692 DEBUG(dbgs() << "X86WinEHState: " << BB->getName()
693 << " FinalState=" << FinalState << '\n');
694 InitialStates.insert({BB, InitialState});
695 FinalStates.insert({BB, FinalState});
698 // Try to fill-in InitialStates and FinalStates which have no call-sites.
699 while (!Worklist.empty()) {
700 BasicBlock *BB = Worklist.front();
701 Worklist.pop_front();
702 // This BasicBlock has already been figured out, nothing more we can do.
703 if (InitialStates.count(BB) != 0)
706 int PredState = getPredState(FinalStates, F, ParentBaseState, BB);
707 if (PredState == OverdefinedState)
710 // We successfully inferred this BasicBlock's state via it's predecessors;
711 // enqueue it's successors to see if we can infer their states.
712 InitialStates.insert({BB, PredState});
713 FinalStates.insert({BB, PredState});
714 for (BasicBlock *SuccBB : successors(BB))
715 Worklist.push_back(SuccBB);
718 // Try to hoist stores from successors.
719 for (BasicBlock *BB : RPOT) {
720 int SuccState = getSuccState(InitialStates, F, ParentBaseState, BB);
721 if (SuccState == OverdefinedState)
724 // Update our FinalState to reflect the common InitialState of our
726 FinalStates.insert({BB, SuccState});
729 // Finally, insert state stores before call-sites which transition us to a new
731 for (BasicBlock *BB : RPOT) {
732 auto &BBColors = BlockColors[BB];
733 BasicBlock *FuncletEntryBB = BBColors.front();
734 if (isa<CleanupPadInst>(FuncletEntryBB->getFirstNonPHI()))
737 int PrevState = getPredState(FinalStates, F, ParentBaseState, BB);
738 DEBUG(dbgs() << "X86WinEHState: " << BB->getName()
739 << " PrevState=" << PrevState << '\n');
741 for (Instruction &I : *BB) {
743 if (!isStateStoreNeeded(Personality, CS))
746 int State = getStateForCallSite(BlockColors, FuncInfo, CS);
747 if (State != PrevState)
748 insertStateNumberStore(&I, State);
752 // We might have hoisted a state store into this block, emit it now.
753 auto EndState = FinalStates.find(BB);
754 if (EndState != FinalStates.end())
755 if (EndState->second != PrevState)
756 insertStateNumberStore(BB->getTerminator(), EndState->second);
759 SmallVector<CallSite, 1> SetJmp3CallSites;
760 for (BasicBlock *BB : RPOT) {
761 for (Instruction &I : *BB) {
765 if (CS.getCalledValue()->stripPointerCasts() !=
766 SetJmp3->stripPointerCasts())
769 SetJmp3CallSites.push_back(CS);
773 for (CallSite CS : SetJmp3CallSites) {
774 auto &BBColors = BlockColors[CS->getParent()];
775 BasicBlock *FuncletEntryBB = BBColors.front();
776 bool InCleanup = isa<CleanupPadInst>(FuncletEntryBB->getFirstNonPHI());
778 IRBuilder<> Builder(CS.getInstruction());
782 Builder.CreateStructGEP(nullptr, RegNode, StateFieldIndex);
783 State = Builder.CreateLoad(StateField);
785 State = Builder.getInt32(getStateForCallSite(BlockColors, FuncInfo, CS));
787 rewriteSetJmpCallSite(Builder, F, CS, State);
791 void WinEHStatePass::insertStateNumberStore(Instruction *IP, int State) {
792 IRBuilder<> Builder(IP);
794 Builder.CreateStructGEP(nullptr, RegNode, StateFieldIndex);
795 Builder.CreateStore(Builder.getInt32(State), StateField);