llvm/lib/Target/X86/X86WinEHState.cpp

   1 //===-- X86WinEHState - Insert EH state updates for win32 exceptions ------===//
   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 // All functions using an MSVC EH personality use an explicitly updated state
  10 // number stored in an exception registration stack object. The registration
  11 // object is linked into a thread-local chain of registrations stored at fs:00.
  12 // This pass adds the registration object and EH state updates.
  13 //
  14 //===----------------------------------------------------------------------===//
  15
  16 #include "X86.h"
  17 #include "llvm/ADT/PostOrderIterator.h"
  18 #include "llvm/Analysis/CFG.h"
  19 #include "llvm/CodeGen/MachineModuleInfo.h"
  20 #include "llvm/CodeGen/WinEHFuncInfo.h"
  21 #include "llvm/IR/CFG.h"
  22 #include "llvm/IR/EHPersonalities.h"
  23 #include "llvm/IR/Function.h"
  24 #include "llvm/IR/IRBuilder.h"
  25 #include "llvm/IR/Instructions.h"
  26 #include "llvm/IR/Intrinsics.h"
  27 #include "llvm/IR/IntrinsicsX86.h"
  28 #include "llvm/IR/Module.h"
  29 #include "llvm/Pass.h"
  30 #include "llvm/Support/Debug.h"
  31 #include <deque>
  32
  33 using namespace llvm;
  34
  35 #define DEBUG_TYPE "winehstate"
  36
  37 namespace {
  38 const int OverdefinedState = INT_MIN;
  39
  40 class WinEHStatePass : public FunctionPass {
  41 public:
  42   static char ID; // Pass identification, replacement for typeid.
  43
  44   WinEHStatePass() : FunctionPass(ID) { }
  45
  46   bool runOnFunction(Function &Fn) override;
  47
  48   bool doInitialization(Module &M) override;
  49
  50   bool doFinalization(Module &M) override;
  51
  52   void getAnalysisUsage(AnalysisUsage &AU) const override;
  53
  54   StringRef getPassName() const override {
  55     return "Windows 32-bit x86 EH state insertion";
  56   }
  57
  58 private:
  59   void emitExceptionRegistrationRecord(Function *F);
  60
  61   void linkExceptionRegistration(IRBuilder<> &Builder, Function *Handler);
  62   void unlinkExceptionRegistration(IRBuilder<> &Builder);
  63   void addStateStores(Function &F, WinEHFuncInfo &FuncInfo);
  64   void insertStateNumberStore(Instruction *IP, int State);
  65
  66   Value *emitEHLSDA(IRBuilder<> &Builder, Function *F);
  67
  68   Function *generateLSDAInEAXThunk(Function *ParentFunc);
  69
  70   bool isStateStoreNeeded(EHPersonality Personality, CallBase &Call);
  71   void rewriteSetJmpCall(IRBuilder<> &Builder, Function &F, CallBase &Call,
  72                          Value *State);
  73   int getBaseStateForBB(DenseMap<BasicBlock *, ColorVector> &BlockColors,
  74                         WinEHFuncInfo &FuncInfo, BasicBlock *BB);
  75   int getStateForCall(DenseMap<BasicBlock *, ColorVector> &BlockColors,
  76                       WinEHFuncInfo &FuncInfo, CallBase &Call);
  77
  78   // Module-level type getters.
  79   Type *getEHLinkRegistrationType();
  80   Type *getSEHRegistrationType();
  81   Type *getCXXEHRegistrationType();
  82
  83   // Per-module data.
  84   Module *TheModule = nullptr;
  85   StructType *EHLinkRegistrationTy = nullptr;
  86   StructType *CXXEHRegistrationTy = nullptr;
  87   StructType *SEHRegistrationTy = nullptr;
  88   FunctionCallee SetJmp3 = nullptr;
  89   FunctionCallee CxxLongjmpUnwind = nullptr;
  90
  91   // Per-function state
  92   EHPersonality Personality = EHPersonality::Unknown;
  93   Function *PersonalityFn = nullptr;
  94   bool UseStackGuard = false;
  95   int ParentBaseState = 0;
  96   FunctionCallee SehLongjmpUnwind = nullptr;
  97   Constant *Cookie = nullptr;
  98
  99   /// The stack allocation containing all EH data, including the link in the
 100   /// fs:00 chain and the current state.
 101   AllocaInst *RegNode = nullptr;
 102
 103   // The allocation containing the EH security guard.
 104   AllocaInst *EHGuardNode = nullptr;
 105
 106   /// The index of the state field of RegNode.
 107   int StateFieldIndex = ~0U;
 108
 109   /// The linked list node subobject inside of RegNode.
 110   Value *Link = nullptr;
 111 };
 112 } // namespace
 113
 114 FunctionPass *llvm::createX86WinEHStatePass() { return new WinEHStatePass(); }
 115
 116 char WinEHStatePass::ID = 0;
 117
 118 INITIALIZE_PASS(WinEHStatePass, "x86-winehstate",
 119                 "Insert stores for EH state numbers", false, false)
 120
 121 bool WinEHStatePass::doInitialization(Module &M) {
 122   TheModule = &M;
 123   return false;
 124 }
 125
 126 bool WinEHStatePass::doFinalization(Module &M) {
 127   assert(TheModule == &M);
 128   TheModule = nullptr;
 129   EHLinkRegistrationTy = nullptr;
 130   CXXEHRegistrationTy = nullptr;
 131   SEHRegistrationTy = nullptr;
 132   SetJmp3 = nullptr;
 133   CxxLongjmpUnwind = nullptr;
 134   SehLongjmpUnwind = nullptr;
 135   Cookie = nullptr;
 136   return false;
 137 }
 138
 139 void WinEHStatePass::getAnalysisUsage(AnalysisUsage &AU) const {
 140   // This pass should only insert a stack allocation, memory accesses, and
 141   // localrecovers.
 142   AU.setPreservesCFG();
 143 }
 144
 145 bool WinEHStatePass::runOnFunction(Function &F) {
 146   // Don't insert state stores or exception handler thunks for
 147   // available_externally functions. The handler needs to reference the LSDA,
 148   // which will not be emitted in this case.
 149   if (F.hasAvailableExternallyLinkage())
 150     return false;
 151
 152   // Check the personality. Do nothing if this personality doesn't use funclets.
 153   if (!F.hasPersonalityFn())
 154     return false;
 155   PersonalityFn =
 156       dyn_cast<Function>(F.getPersonalityFn()->stripPointerCasts());
 157   if (!PersonalityFn)
 158     return false;
 159   Personality = classifyEHPersonality(PersonalityFn);
 160   if (!isFuncletEHPersonality(Personality))
 161     return false;
 162
 163   // Skip this function if there are no EH pads and we aren't using IR-level
 164   // outlining.
 165   bool HasPads = false;
 166   for (BasicBlock &BB : F) {
 167     if (BB.isEHPad()) {
 168       HasPads = true;
 169       break;
 170     }
 171   }
 172   if (!HasPads)
 173     return false;
 174
 175   Type *Int8PtrType = PointerType::getUnqual(TheModule->getContext());
 176   SetJmp3 = TheModule->getOrInsertFunction(
 177       "_setjmp3", FunctionType::get(
 178                       Type::getInt32Ty(TheModule->getContext()),
 179                       {Int8PtrType, Type::getInt32Ty(TheModule->getContext())},
 180                       /*isVarArg=*/true));
 181
 182   emitExceptionRegistrationRecord(&F);
 183
 184   // The state numbers calculated here in IR must agree with what we calculate
 185   // later on for the MachineFunction. In particular, if an IR pass deletes an
 186   // unreachable EH pad after this point before machine CFG construction, we
 187   // will be in trouble. If this assumption is ever broken, we should turn the
 188   // numbers into an immutable analysis pass.
 189   WinEHFuncInfo FuncInfo;
 190   addStateStores(F, FuncInfo);
 191
 192   // Reset per-function state.
 193   PersonalityFn = nullptr;
 194   Personality = EHPersonality::Unknown;
 195   UseStackGuard = false;
 196   RegNode = nullptr;
 197   EHGuardNode = nullptr;
 198
 199   return true;
 200 }
 201
 202 /// Get the common EH registration subobject:
 203 ///   typedef _EXCEPTION_DISPOSITION (*PEXCEPTION_ROUTINE)(
 204 ///       _EXCEPTION_RECORD *, void *, _CONTEXT *, void *);
 205 ///   struct EHRegistrationNode {
 206 ///     EHRegistrationNode *Next;
 207 ///     PEXCEPTION_ROUTINE Handler;
 208 ///   };
 209 Type *WinEHStatePass::getEHLinkRegistrationType() {
 210   if (EHLinkRegistrationTy)
 211     return EHLinkRegistrationTy;
 212   LLVMContext &Context = TheModule->getContext();
 213   EHLinkRegistrationTy = StructType::create(Context, "EHRegistrationNode");
 214   Type *FieldTys[] = {
 215       PointerType::getUnqual(
 216           EHLinkRegistrationTy->getContext()), // EHRegistrationNode *Next
 217       PointerType::getUnqual(Context) // EXCEPTION_DISPOSITION (*Handler)(...)
 218   };
 219   EHLinkRegistrationTy->setBody(FieldTys, false);
 220   return EHLinkRegistrationTy;
 221 }
 222
 223 /// The __CxxFrameHandler3 registration node:
 224 ///   struct CXXExceptionRegistration {
 225 ///     void *SavedESP;
 226 ///     EHRegistrationNode SubRecord;
 227 ///     int32_t TryLevel;
 228 ///   };
 229 Type *WinEHStatePass::getCXXEHRegistrationType() {
 230   if (CXXEHRegistrationTy)
 231     return CXXEHRegistrationTy;
 232   LLVMContext &Context = TheModule->getContext();
 233   Type *FieldTys[] = {
 234       PointerType::getUnqual(Context), // void *SavedESP
 235       getEHLinkRegistrationType(),     // EHRegistrationNode SubRecord
 236       Type::getInt32Ty(Context)        // int32_t TryLevel
 237   };
 238   CXXEHRegistrationTy =
 239       StructType::create(FieldTys, "CXXExceptionRegistration");
 240   return CXXEHRegistrationTy;
 241 }
 242
 243 /// The _except_handler3/4 registration node:
 244 ///   struct EH4ExceptionRegistration {
 245 ///     void *SavedESP;
 246 ///     _EXCEPTION_POINTERS *ExceptionPointers;
 247 ///     EHRegistrationNode SubRecord;
 248 ///     int32_t EncodedScopeTable;
 249 ///     int32_t TryLevel;
 250 ///   };
 251 Type *WinEHStatePass::getSEHRegistrationType() {
 252   if (SEHRegistrationTy)
 253     return SEHRegistrationTy;
 254   LLVMContext &Context = TheModule->getContext();
 255   Type *FieldTys[] = {
 256       PointerType::getUnqual(Context), // void *SavedESP
 257       PointerType::getUnqual(Context), // void *ExceptionPointers
 258       getEHLinkRegistrationType(),     // EHRegistrationNode SubRecord
 259       Type::getInt32Ty(Context),       // int32_t EncodedScopeTable
 260       Type::getInt32Ty(Context)        // int32_t TryLevel
 261   };
 262   SEHRegistrationTy = StructType::create(FieldTys, "SEHExceptionRegistration");
 263   return SEHRegistrationTy;
 264 }
 265
 266 // Emit an exception registration record. These are stack allocations with the
 267 // common subobject of two pointers: the previous registration record (the old
 268 // fs:00) and the personality function for the current frame. The data before
 269 // and after that is personality function specific.
 270 void WinEHStatePass::emitExceptionRegistrationRecord(Function *F) {
 271   assert(Personality == EHPersonality::MSVC_CXX ||
 272          Personality == EHPersonality::MSVC_X86SEH);
 273
 274   // Struct type of RegNode. Used for GEPing.
 275   Type *RegNodeTy;
 276
 277   IRBuilder<> Builder(&F->getEntryBlock(), F->getEntryBlock().begin());
 278   Type *Int8PtrType = Builder.getPtrTy();
 279   Type *Int32Ty = Builder.getInt32Ty();
 280   Type *VoidTy = Builder.getVoidTy();
 281
 282   if (Personality == EHPersonality::MSVC_CXX) {
 283     RegNodeTy = getCXXEHRegistrationType();
 284     RegNode = Builder.CreateAlloca(RegNodeTy);
 285     // SavedESP = llvm.stacksave()
 286     Value *SP = Builder.CreateStackSave();
 287     Builder.CreateStore(SP, Builder.CreateStructGEP(RegNodeTy, RegNode, 0));
 288     // TryLevel = -1
 289     StateFieldIndex = 2;
 290     ParentBaseState = -1;
 291     insertStateNumberStore(&*Builder.GetInsertPoint(), ParentBaseState);
 292     // Handler = __ehhandler$F
 293     Function *Trampoline = generateLSDAInEAXThunk(F);
 294     Link = Builder.CreateStructGEP(RegNodeTy, RegNode, 1);
 295     linkExceptionRegistration(Builder, Trampoline);
 296
 297     CxxLongjmpUnwind = TheModule->getOrInsertFunction(
 298         "__CxxLongjmpUnwind",
 299         FunctionType::get(VoidTy, Int8PtrType, /*isVarArg=*/false));
 300     cast<Function>(CxxLongjmpUnwind.getCallee()->stripPointerCasts())
 301         ->setCallingConv(CallingConv::X86_StdCall);
 302   } else if (Personality == EHPersonality::MSVC_X86SEH) {
 303     // If _except_handler4 is in use, some additional guard checks and prologue
 304     // stuff is required.
 305     StringRef PersonalityName = PersonalityFn->getName();
 306     UseStackGuard = (PersonalityName == "_except_handler4");
 307
 308     // Allocate local structures.
 309     RegNodeTy = getSEHRegistrationType();
 310     RegNode = Builder.CreateAlloca(RegNodeTy);
 311     if (UseStackGuard)
 312       EHGuardNode = Builder.CreateAlloca(Int32Ty);
 313
 314     // SavedESP = llvm.stacksave()
 315     Value *SP = Builder.CreateStackSave();
 316     Builder.CreateStore(SP, Builder.CreateStructGEP(RegNodeTy, RegNode, 0));
 317     // TryLevel = -2 / -1
 318     StateFieldIndex = 4;
 319     ParentBaseState = UseStackGuard ? -2 : -1;
 320     insertStateNumberStore(&*Builder.GetInsertPoint(), ParentBaseState);
 321     // ScopeTable = llvm.x86.seh.lsda(F)
 322     Value *LSDA = emitEHLSDA(Builder, F);
 323     LSDA = Builder.CreatePtrToInt(LSDA, Int32Ty);
 324     // If using _except_handler4, xor the address of the table with
 325     // __security_cookie.
 326     if (UseStackGuard) {
 327       Cookie = TheModule->getOrInsertGlobal("__security_cookie", Int32Ty);
 328       Value *Val = Builder.CreateLoad(Int32Ty, Cookie, "cookie");
 329       LSDA = Builder.CreateXor(LSDA, Val);
 330     }
 331     Builder.CreateStore(LSDA, Builder.CreateStructGEP(RegNodeTy, RegNode, 3));
 332
 333     // If using _except_handler4, the EHGuard contains: FramePtr xor Cookie.
 334     if (UseStackGuard) {
 335       Value *Val = Builder.CreateLoad(Int32Ty, Cookie);
 336       Value *FrameAddr = Builder.CreateCall(
 337           Intrinsic::getDeclaration(
 338               TheModule, Intrinsic::frameaddress,
 339               Builder.getPtrTy(
 340                   TheModule->getDataLayout().getAllocaAddrSpace())),
 341           Builder.getInt32(0), "frameaddr");
 342       Value *FrameAddrI32 = Builder.CreatePtrToInt(FrameAddr, Int32Ty);
 343       FrameAddrI32 = Builder.CreateXor(FrameAddrI32, Val);
 344       Builder.CreateStore(FrameAddrI32, EHGuardNode);
 345     }
 346
 347     // Register the exception handler.
 348     Link = Builder.CreateStructGEP(RegNodeTy, RegNode, 2);
 349     linkExceptionRegistration(Builder, PersonalityFn);
 350
 351     SehLongjmpUnwind = TheModule->getOrInsertFunction(
 352         UseStackGuard ? "_seh_longjmp_unwind4" : "_seh_longjmp_unwind",
 353         FunctionType::get(Type::getVoidTy(TheModule->getContext()), Int8PtrType,
 354                           /*isVarArg=*/false));
 355     cast<Function>(SehLongjmpUnwind.getCallee()->stripPointerCasts())
 356         ->setCallingConv(CallingConv::X86_StdCall);
 357   } else {
 358     llvm_unreachable("unexpected personality function");
 359   }
 360
 361   // Insert an unlink before all returns.
 362   for (BasicBlock &BB : *F) {
 363     Instruction *T = BB.getTerminator();
 364     if (!isa<ReturnInst>(T))
 365       continue;
 366     Builder.SetInsertPoint(T);
 367     unlinkExceptionRegistration(Builder);
 368   }
 369 }
 370
 371 Value *WinEHStatePass::emitEHLSDA(IRBuilder<> &Builder, Function *F) {
 372   return Builder.CreateCall(
 373       Intrinsic::getDeclaration(TheModule, Intrinsic::x86_seh_lsda), F);
 374 }
 375
 376 /// Generate a thunk that puts the LSDA of ParentFunc in EAX and then calls
 377 /// PersonalityFn, forwarding the parameters passed to PEXCEPTION_ROUTINE:
 378 ///   typedef _EXCEPTION_DISPOSITION (*PEXCEPTION_ROUTINE)(
 379 ///       _EXCEPTION_RECORD *, void *, _CONTEXT *, void *);
 380 /// We essentially want this code:
 381 ///   movl $lsda, %eax
 382 ///   jmpl ___CxxFrameHandler3
 383 Function *WinEHStatePass::generateLSDAInEAXThunk(Function *ParentFunc) {
 384   LLVMContext &Context = ParentFunc->getContext();
 385   Type *Int32Ty = Type::getInt32Ty(Context);
 386   Type *Int8PtrType = PointerType::getUnqual(Context);
 387   Type *ArgTys[5] = {Int8PtrType, Int8PtrType, Int8PtrType, Int8PtrType,
 388                      Int8PtrType};
 389   FunctionType *TrampolineTy =
 390       FunctionType::get(Int32Ty, ArrayRef(&ArgTys[0], 4),
 391                         /*isVarArg=*/false);
 392   FunctionType *TargetFuncTy =
 393       FunctionType::get(Int32Ty, ArrayRef(&ArgTys[0], 5),
 394                         /*isVarArg=*/false);
 395   Function *Trampoline =
 396       Function::Create(TrampolineTy, GlobalValue::InternalLinkage,
 397                        Twine("__ehhandler$") + GlobalValue::dropLLVMManglingEscape(
 398                                                    ParentFunc->getName()),
 399                        TheModule);
 400   if (auto *C = ParentFunc->getComdat())
 401     Trampoline->setComdat(C);
 402   BasicBlock *EntryBB = BasicBlock::Create(Context, "entry", Trampoline);
 403   IRBuilder<> Builder(EntryBB);
 404   Value *LSDA = emitEHLSDA(Builder, ParentFunc);
 405   auto AI = Trampoline->arg_begin();
 406   Value *Args[5] = {LSDA, &*AI++, &*AI++, &*AI++, &*AI++};
 407   CallInst *Call = Builder.CreateCall(TargetFuncTy, PersonalityFn, Args);
 408   // Can't use musttail due to prototype mismatch, but we can use tail.
 409   Call->setTailCall(true);
 410   // Set inreg so we pass it in EAX.
 411   Call->addParamAttr(0, Attribute::InReg);
 412   Builder.CreateRet(Call);
 413   return Trampoline;
 414 }
 415
 416 void WinEHStatePass::linkExceptionRegistration(IRBuilder<> &Builder,
 417                                                Function *Handler) {
 418   // Emit the .safeseh directive for this function.
 419   Handler->addFnAttr("safeseh");
 420
 421   LLVMContext &C = Builder.getContext();
 422   Type *LinkTy = getEHLinkRegistrationType();
 423   // Handler = Handler
 424   Builder.CreateStore(Handler, Builder.CreateStructGEP(LinkTy, Link, 1));
 425   // Next = [fs:00]
 426   Constant *FSZero = Constant::getNullValue(PointerType::get(C, 257));
 427   Value *Next = Builder.CreateLoad(PointerType::getUnqual(C), FSZero);
 428   Builder.CreateStore(Next, Builder.CreateStructGEP(LinkTy, Link, 0));
 429   // [fs:00] = Link
 430   Builder.CreateStore(Link, FSZero);
 431 }
 432
 433 void WinEHStatePass::unlinkExceptionRegistration(IRBuilder<> &Builder) {
 434   // Clone Link into the current BB for better address mode folding.
 435   if (auto *GEP = dyn_cast<GetElementPtrInst>(Link)) {
 436     GEP = cast<GetElementPtrInst>(GEP->clone());
 437     Builder.Insert(GEP);
 438     Link = GEP;
 439   }
 440
 441   LLVMContext &C = Builder.getContext();
 442   Type *LinkTy = getEHLinkRegistrationType();
 443   // [fs:00] = Link->Next
 444   Value *Next = Builder.CreateLoad(PointerType::getUnqual(C),
 445                                    Builder.CreateStructGEP(LinkTy, Link, 0));
 446   Constant *FSZero = Constant::getNullValue(PointerType::get(C, 257));
 447   Builder.CreateStore(Next, FSZero);
 448 }
 449
 450 // Calls to setjmp(p) are lowered to _setjmp3(p, 0) by the frontend.
 451 // The idea behind _setjmp3 is that it takes an optional number of personality
 452 // specific parameters to indicate how to restore the personality-specific frame
 453 // state when longjmp is initiated.  Typically, the current TryLevel is saved.
 454 void WinEHStatePass::rewriteSetJmpCall(IRBuilder<> &Builder, Function &F,
 455                                        CallBase &Call, Value *State) {
 456   // Don't rewrite calls with a weird number of arguments.
 457   if (Call.arg_size() != 2)
 458     return;
 459
 460   SmallVector<OperandBundleDef, 1> OpBundles;
 461   Call.getOperandBundlesAsDefs(OpBundles);
 462
 463   SmallVector<Value *, 3> OptionalArgs;
 464   if (Personality == EHPersonality::MSVC_CXX) {
 465     OptionalArgs.push_back(CxxLongjmpUnwind.getCallee());
 466     OptionalArgs.push_back(State);
 467     OptionalArgs.push_back(emitEHLSDA(Builder, &F));
 468   } else if (Personality == EHPersonality::MSVC_X86SEH) {
 469     OptionalArgs.push_back(SehLongjmpUnwind.getCallee());
 470     OptionalArgs.push_back(State);
 471     if (UseStackGuard)
 472       OptionalArgs.push_back(Cookie);
 473   } else {
 474     llvm_unreachable("unhandled personality!");
 475   }
 476
 477   SmallVector<Value *, 5> Args;
 478   Args.push_back(
 479       Builder.CreateBitCast(Call.getArgOperand(0), Builder.getPtrTy()));
 480   Args.push_back(Builder.getInt32(OptionalArgs.size()));
 481   Args.append(OptionalArgs.begin(), OptionalArgs.end());
 482
 483   CallBase *NewCall;
 484   if (auto *CI = dyn_cast<CallInst>(&Call)) {
 485     CallInst *NewCI = Builder.CreateCall(SetJmp3, Args, OpBundles);
 486     NewCI->setTailCallKind(CI->getTailCallKind());
 487     NewCall = NewCI;
 488   } else {
 489     auto *II = cast<InvokeInst>(&Call);
 490     NewCall = Builder.CreateInvoke(
 491         SetJmp3, II->getNormalDest(), II->getUnwindDest(), Args, OpBundles);
 492   }
 493   NewCall->setCallingConv(Call.getCallingConv());
 494   NewCall->setAttributes(Call.getAttributes());
 495   NewCall->setDebugLoc(Call.getDebugLoc());
 496
 497   NewCall->takeName(&Call);
 498   Call.replaceAllUsesWith(NewCall);
 499   Call.eraseFromParent();
 500 }
 501
 502 // Figure out what state we should assign calls in this block.
 503 int WinEHStatePass::getBaseStateForBB(
 504     DenseMap<BasicBlock *, ColorVector> &BlockColors, WinEHFuncInfo &FuncInfo,
 505     BasicBlock *BB) {
 506   int BaseState = ParentBaseState;
 507   auto &BBColors = BlockColors[BB];
 508
 509   assert(BBColors.size() == 1 && "multi-color BB not removed by preparation");
 510   BasicBlock *FuncletEntryBB = BBColors.front();
 511   if (auto *FuncletPad =
 512           dyn_cast<FuncletPadInst>(FuncletEntryBB->getFirstNonPHI())) {
 513     auto BaseStateI = FuncInfo.FuncletBaseStateMap.find(FuncletPad);
 514     if (BaseStateI != FuncInfo.FuncletBaseStateMap.end())
 515       BaseState = BaseStateI->second;
 516   }
 517
 518   return BaseState;
 519 }
 520
 521 // Calculate the state a call-site is in.
 522 int WinEHStatePass::getStateForCall(
 523     DenseMap<BasicBlock *, ColorVector> &BlockColors, WinEHFuncInfo &FuncInfo,
 524     CallBase &Call) {
 525   if (auto *II = dyn_cast<InvokeInst>(&Call)) {
 526     // Look up the state number of the EH pad this unwinds to.
 527     assert(FuncInfo.InvokeStateMap.count(II) && "invoke has no state!");
 528     return FuncInfo.InvokeStateMap[II];
 529   }
 530   // Possibly throwing call instructions have no actions to take after
 531   // an unwind. Ensure they are in the -1 state.
 532   return getBaseStateForBB(BlockColors, FuncInfo, Call.getParent());
 533 }
 534
 535 // Calculate the intersection of all the FinalStates for a BasicBlock's
 536 // predecessors.
 537 static int getPredState(DenseMap<BasicBlock *, int> &FinalStates, Function &F,
 538                         int ParentBaseState, BasicBlock *BB) {
 539   // The entry block has no predecessors but we know that the prologue always
 540   // sets us up with a fixed state.
 541   if (&F.getEntryBlock() == BB)
 542     return ParentBaseState;
 543
 544   // This is an EH Pad, conservatively report this basic block as overdefined.
 545   if (BB->isEHPad())
 546     return OverdefinedState;
 547
 548   int CommonState = OverdefinedState;
 549   for (BasicBlock *PredBB : predecessors(BB)) {
 550     // We didn't manage to get a state for one of these predecessors,
 551     // conservatively report this basic block as overdefined.
 552     auto PredEndState = FinalStates.find(PredBB);
 553     if (PredEndState == FinalStates.end())
 554       return OverdefinedState;
 555
 556     // This code is reachable via exceptional control flow,
 557     // conservatively report this basic block as overdefined.
 558     if (isa<CatchReturnInst>(PredBB->getTerminator()))
 559       return OverdefinedState;
 560
 561     int PredState = PredEndState->second;
 562     assert(PredState != OverdefinedState &&
 563            "overdefined BBs shouldn't be in FinalStates");
 564     if (CommonState == OverdefinedState)
 565       CommonState = PredState;
 566
 567     // At least two predecessors have different FinalStates,
 568     // conservatively report this basic block as overdefined.
 569     if (CommonState != PredState)
 570       return OverdefinedState;
 571   }
 572
 573   return CommonState;
 574 }
 575
 576 // Calculate the intersection of all the InitialStates for a BasicBlock's
 577 // successors.
 578 static int getSuccState(DenseMap<BasicBlock *, int> &InitialStates, Function &F,
 579                         int ParentBaseState, BasicBlock *BB) {
 580   // This block rejoins normal control flow,
 581   // conservatively report this basic block as overdefined.
 582   if (isa<CatchReturnInst>(BB->getTerminator()))
 583     return OverdefinedState;
 584
 585   int CommonState = OverdefinedState;
 586   for (BasicBlock *SuccBB : successors(BB)) {
 587     // We didn't manage to get a state for one of these predecessors,
 588     // conservatively report this basic block as overdefined.
 589     auto SuccStartState = InitialStates.find(SuccBB);
 590     if (SuccStartState == InitialStates.end())
 591       return OverdefinedState;
 592
 593     // This is an EH Pad, conservatively report this basic block as overdefined.
 594     if (SuccBB->isEHPad())
 595       return OverdefinedState;
 596
 597     int SuccState = SuccStartState->second;
 598     assert(SuccState != OverdefinedState &&
 599            "overdefined BBs shouldn't be in FinalStates");
 600     if (CommonState == OverdefinedState)
 601       CommonState = SuccState;
 602
 603     // At least two successors have different InitialStates,
 604     // conservatively report this basic block as overdefined.
 605     if (CommonState != SuccState)
 606       return OverdefinedState;
 607   }
 608
 609   return CommonState;
 610 }
 611
 612 bool WinEHStatePass::isStateStoreNeeded(EHPersonality Personality,
 613                                         CallBase &Call) {
 614   // If the function touches memory, it needs a state store.
 615   if (isAsynchronousEHPersonality(Personality))
 616     return !Call.doesNotAccessMemory();
 617
 618   // If the function throws, it needs a state store.
 619   return !Call.doesNotThrow();
 620 }
 621
 622 void WinEHStatePass::addStateStores(Function &F, WinEHFuncInfo &FuncInfo) {
 623   // Mark the registration node. The backend needs to know which alloca it is so
 624   // that it can recover the original frame pointer.
 625   IRBuilder<> Builder(RegNode->getNextNode());
 626   Value *RegNodeI8 = Builder.CreateBitCast(RegNode, Builder.getPtrTy());
 627   Builder.CreateCall(
 628       Intrinsic::getDeclaration(TheModule, Intrinsic::x86_seh_ehregnode),
 629       {RegNodeI8});
 630
 631   if (EHGuardNode) {
 632     IRBuilder<> Builder(EHGuardNode->getNextNode());
 633     Value *EHGuardNodeI8 =
 634         Builder.CreateBitCast(EHGuardNode, Builder.getPtrTy());
 635     Builder.CreateCall(
 636         Intrinsic::getDeclaration(TheModule, Intrinsic::x86_seh_ehguard),
 637         {EHGuardNodeI8});
 638   }
 639
 640   // Calculate state numbers.
 641   if (isAsynchronousEHPersonality(Personality))
 642     calculateSEHStateNumbers(&F, FuncInfo);
 643   else
 644     calculateWinCXXEHStateNumbers(&F, FuncInfo);
 645
 646   // Iterate all the instructions and emit state number stores.
 647   DenseMap<BasicBlock *, ColorVector> BlockColors = colorEHFunclets(F);
 648   ReversePostOrderTraversal<Function *> RPOT(&F);
 649
 650   // InitialStates yields the state of the first call-site for a BasicBlock.
 651   DenseMap<BasicBlock *, int> InitialStates;
 652   // FinalStates yields the state of the last call-site for a BasicBlock.
 653   DenseMap<BasicBlock *, int> FinalStates;
 654   // Worklist used to revisit BasicBlocks with indeterminate
 655   // Initial/Final-States.
 656   std::deque<BasicBlock *> Worklist;
 657   // Fill in InitialStates and FinalStates for BasicBlocks with call-sites.
 658   for (BasicBlock *BB : RPOT) {
 659     int InitialState = OverdefinedState;
 660     int FinalState;
 661     if (&F.getEntryBlock() == BB)
 662       InitialState = FinalState = ParentBaseState;
 663     for (Instruction &I : *BB) {
 664       auto *Call = dyn_cast<CallBase>(&I);
 665       if (!Call || !isStateStoreNeeded(Personality, *Call))
 666         continue;
 667
 668       int State = getStateForCall(BlockColors, FuncInfo, *Call);
 669       if (InitialState == OverdefinedState)
 670         InitialState = State;
 671       FinalState = State;
 672     }
 673     // No call-sites in this basic block? That's OK, we will come back to these
 674     // in a later pass.
 675     if (InitialState == OverdefinedState) {
 676       Worklist.push_back(BB);
 677       continue;
 678     }
 679     LLVM_DEBUG(dbgs() << "X86WinEHState: " << BB->getName()
 680                       << " InitialState=" << InitialState << '\n');
 681     LLVM_DEBUG(dbgs() << "X86WinEHState: " << BB->getName()
 682                       << " FinalState=" << FinalState << '\n');
 683     InitialStates.insert({BB, InitialState});
 684     FinalStates.insert({BB, FinalState});
 685   }
 686
 687   // Try to fill-in InitialStates and FinalStates which have no call-sites.
 688   while (!Worklist.empty()) {
 689     BasicBlock *BB = Worklist.front();
 690     Worklist.pop_front();
 691     // This BasicBlock has already been figured out, nothing more we can do.
 692     if (InitialStates.count(BB) != 0)
 693       continue;
 694
 695     int PredState = getPredState(FinalStates, F, ParentBaseState, BB);
 696     if (PredState == OverdefinedState)
 697       continue;
 698
 699     // We successfully inferred this BasicBlock's state via it's predecessors;
 700     // enqueue it's successors to see if we can infer their states.
 701     InitialStates.insert({BB, PredState});
 702     FinalStates.insert({BB, PredState});
 703     for (BasicBlock *SuccBB : successors(BB))
 704       Worklist.push_back(SuccBB);
 705   }
 706
 707   // Try to hoist stores from successors.
 708   for (BasicBlock *BB : RPOT) {
 709     int SuccState = getSuccState(InitialStates, F, ParentBaseState, BB);
 710     if (SuccState == OverdefinedState)
 711       continue;
 712
 713     // Update our FinalState to reflect the common InitialState of our
 714     // successors.
 715     FinalStates.insert({BB, SuccState});
 716   }
 717
 718   // Finally, insert state stores before call-sites which transition us to a new
 719   // state.
 720   for (BasicBlock *BB : RPOT) {
 721     auto &BBColors = BlockColors[BB];
 722     BasicBlock *FuncletEntryBB = BBColors.front();
 723     if (isa<CleanupPadInst>(FuncletEntryBB->getFirstNonPHI()))
 724       continue;
 725
 726     int PrevState = getPredState(FinalStates, F, ParentBaseState, BB);
 727     LLVM_DEBUG(dbgs() << "X86WinEHState: " << BB->getName()
 728                       << " PrevState=" << PrevState << '\n');
 729
 730     for (Instruction &I : *BB) {
 731       auto *Call = dyn_cast<CallBase>(&I);
 732       if (!Call || !isStateStoreNeeded(Personality, *Call))
 733         continue;
 734
 735       int State = getStateForCall(BlockColors, FuncInfo, *Call);
 736       if (State != PrevState)
 737         insertStateNumberStore(&I, State);
 738       PrevState = State;
 739     }
 740
 741     // We might have hoisted a state store into this block, emit it now.
 742     auto EndState = FinalStates.find(BB);
 743     if (EndState != FinalStates.end())
 744       if (EndState->second != PrevState)
 745         insertStateNumberStore(BB->getTerminator(), EndState->second);
 746   }
 747
 748   SmallVector<CallBase *, 1> SetJmp3Calls;
 749   for (BasicBlock *BB : RPOT) {
 750     for (Instruction &I : *BB) {
 751       auto *Call = dyn_cast<CallBase>(&I);
 752       if (!Call)
 753         continue;
 754       if (Call->getCalledOperand()->stripPointerCasts() !=
 755           SetJmp3.getCallee()->stripPointerCasts())
 756         continue;
 757
 758       SetJmp3Calls.push_back(Call);
 759     }
 760   }
 761
 762   for (CallBase *Call : SetJmp3Calls) {
 763     auto &BBColors = BlockColors[Call->getParent()];
 764     BasicBlock *FuncletEntryBB = BBColors.front();
 765     bool InCleanup = isa<CleanupPadInst>(FuncletEntryBB->getFirstNonPHI());
 766
 767     IRBuilder<> Builder(Call);
 768     Value *State;
 769     if (InCleanup) {
 770       Value *StateField = Builder.CreateStructGEP(RegNode->getAllocatedType(),
 771                                                   RegNode, StateFieldIndex);
 772       State = Builder.CreateLoad(Builder.getInt32Ty(), StateField);
 773     } else {
 774       State = Builder.getInt32(getStateForCall(BlockColors, FuncInfo, *Call));
 775     }
 776     rewriteSetJmpCall(Builder, F, *Call, State);
 777   }
 778 }
 779
 780 void WinEHStatePass::insertStateNumberStore(Instruction *IP, int State) {
 781   IRBuilder<> Builder(IP);
 782   Value *StateField = Builder.CreateStructGEP(RegNode->getAllocatedType(),
 783                                               RegNode, StateFieldIndex);
 784   Builder.CreateStore(Builder.getInt32(State), StateField);
 785 }