llvm/lib/CodeGen/SjLjEHPrepare.cpp

   1 //===- SjLjEHPrepare.cpp - Eliminate Invoke & Unwind instructions ---------===//
   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 transformation is designed for use by code generators which use SjLj
  10 // based exception handling.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/CodeGen/SjLjEHPrepare.h"
  15 #include "llvm/ADT/SetVector.h"
  16 #include "llvm/ADT/SmallPtrSet.h"
  17 #include "llvm/ADT/SmallVector.h"
  18 #include "llvm/ADT/Statistic.h"
  19 #include "llvm/CodeGen/Passes.h"
  20 #include "llvm/IR/Constants.h"
  21 #include "llvm/IR/DataLayout.h"
  22 #include "llvm/IR/DerivedTypes.h"
  23 #include "llvm/IR/IRBuilder.h"
  24 #include "llvm/IR/Instructions.h"
  25 #include "llvm/IR/Intrinsics.h"
  26 #include "llvm/IR/Module.h"
  27 #include "llvm/InitializePasses.h"
  28 #include "llvm/Pass.h"
  29 #include "llvm/Support/Debug.h"
  30 #include "llvm/Support/raw_ostream.h"
  31 #include "llvm/Target/TargetMachine.h"
  32 #include "llvm/Transforms/Utils/Local.h"
  33 using namespace llvm;
  34
  35 #define DEBUG_TYPE "sjlj-eh-prepare"
  36
  37 STATISTIC(NumInvokes, "Number of invokes replaced");
  38 STATISTIC(NumSpilled, "Number of registers live across unwind edges");
  39
  40 namespace {
  41 class SjLjEHPrepareImpl {
  42   IntegerType *DataTy = nullptr;
  43   Type *doubleUnderDataTy = nullptr;
  44   Type *doubleUnderJBufTy = nullptr;
  45   Type *FunctionContextTy = nullptr;
  46   FunctionCallee RegisterFn;
  47   FunctionCallee UnregisterFn;
  48   Function *BuiltinSetupDispatchFn = nullptr;
  49   Function *FrameAddrFn = nullptr;
  50   Function *StackAddrFn = nullptr;
  51   Function *StackRestoreFn = nullptr;
  52   Function *LSDAAddrFn = nullptr;
  53   Function *CallSiteFn = nullptr;
  54   Function *FuncCtxFn = nullptr;
  55   AllocaInst *FuncCtx = nullptr;
  56   const TargetMachine *TM = nullptr;
  57
  58 public:
  59   explicit SjLjEHPrepareImpl(const TargetMachine *TM = nullptr) : TM(TM) {}
  60   bool doInitialization(Module &M);
  61   bool runOnFunction(Function &F);
  62
  63 private:
  64   bool setupEntryBlockAndCallSites(Function &F);
  65   void substituteLPadValues(LandingPadInst *LPI, Value *ExnVal, Value *SelVal);
  66   Value *setupFunctionContext(Function &F, ArrayRef<LandingPadInst *> LPads);
  67   void lowerIncomingArguments(Function &F);
  68   void lowerAcrossUnwindEdges(Function &F, ArrayRef<InvokeInst *> Invokes);
  69   void insertCallSiteStore(Instruction *I, int Number);
  70 };
  71
  72 class SjLjEHPrepare : public FunctionPass {
  73   SjLjEHPrepareImpl Impl;
  74
  75 public:
  76   static char ID; // Pass identification, replacement for typeid
  77   explicit SjLjEHPrepare(const TargetMachine *TM = nullptr)
  78       : FunctionPass(ID), Impl(TM) {}
  79   bool doInitialization(Module &M) override { return Impl.doInitialization(M); }
  80   bool runOnFunction(Function &F) override { return Impl.runOnFunction(F); };
  81
  82   StringRef getPassName() const override {
  83     return "SJLJ Exception Handling preparation";
  84   }
  85 };
  86
  87 } // end anonymous namespace
  88
  89 PreservedAnalyses SjLjEHPreparePass::run(Function &F,
  90                                          FunctionAnalysisManager &FAM) {
  91   SjLjEHPrepareImpl Impl(TM);
  92   Impl.doInitialization(*F.getParent());
  93   bool Changed = Impl.runOnFunction(F);
  94   return Changed ? PreservedAnalyses::none() : PreservedAnalyses::all();
  95 }
  96
  97 char SjLjEHPrepare::ID = 0;
  98 INITIALIZE_PASS(SjLjEHPrepare, DEBUG_TYPE, "Prepare SjLj exceptions",
  99                 false, false)
 100
 101 // Public Interface To the SjLjEHPrepare pass.
 102 FunctionPass *llvm::createSjLjEHPreparePass(const TargetMachine *TM) {
 103   return new SjLjEHPrepare(TM);
 104 }
 105
 106 // doInitialization - Set up decalarations and types needed to process
 107 // exceptions.
 108 bool SjLjEHPrepareImpl::doInitialization(Module &M) {
 109   // Build the function context structure.
 110   // builtin_setjmp uses a five word jbuf
 111   Type *VoidPtrTy = PointerType::getUnqual(M.getContext());
 112   unsigned DataBits =
 113       TM ? TM->getSjLjDataSize() : TargetMachine::DefaultSjLjDataSize;
 114   DataTy = Type::getIntNTy(M.getContext(), DataBits);
 115   doubleUnderDataTy = ArrayType::get(DataTy, 4);
 116   doubleUnderJBufTy = ArrayType::get(VoidPtrTy, 5);
 117   FunctionContextTy = StructType::get(VoidPtrTy,         // __prev
 118                                       DataTy,            // call_site
 119                                       doubleUnderDataTy, // __data
 120                                       VoidPtrTy,         // __personality
 121                                       VoidPtrTy,         // __lsda
 122                                       doubleUnderJBufTy  // __jbuf
 123   );
 124
 125   return false;
 126 }
 127
 128 /// insertCallSiteStore - Insert a store of the call-site value to the
 129 /// function context
 130 void SjLjEHPrepareImpl::insertCallSiteStore(Instruction *I, int Number) {
 131   IRBuilder<> Builder(I);
 132
 133   // Get a reference to the call_site field.
 134   Type *Int32Ty = Type::getInt32Ty(I->getContext());
 135   Value *Zero = ConstantInt::get(Int32Ty, 0);
 136   Value *One = ConstantInt::get(Int32Ty, 1);
 137   Value *Idxs[2] = { Zero, One };
 138   Value *CallSite =
 139       Builder.CreateGEP(FunctionContextTy, FuncCtx, Idxs, "call_site");
 140
 141   // Insert a store of the call-site number
 142   ConstantInt *CallSiteNoC = ConstantInt::get(DataTy, Number);
 143   Builder.CreateStore(CallSiteNoC, CallSite, true /*volatile*/);
 144 }
 145
 146 /// MarkBlocksLiveIn - Insert BB and all of its predecessors into LiveBBs until
 147 /// we reach blocks we've already seen.
 148 static void MarkBlocksLiveIn(BasicBlock *BB,
 149                              SmallPtrSetImpl<BasicBlock *> &LiveBBs) {
 150   if (!LiveBBs.insert(BB).second)
 151     return; // already been here.
 152
 153   for (BasicBlock *B : inverse_depth_first(BB))
 154     LiveBBs.insert(B);
 155 }
 156
 157 /// substituteLPadValues - Substitute the values returned by the landingpad
 158 /// instruction with those returned by the personality function.
 159 void SjLjEHPrepareImpl::substituteLPadValues(LandingPadInst *LPI, Value *ExnVal,
 160                                              Value *SelVal) {
 161   SmallVector<Value *, 8> UseWorkList(LPI->users());
 162   while (!UseWorkList.empty()) {
 163     Value *Val = UseWorkList.pop_back_val();
 164     auto *EVI = dyn_cast<ExtractValueInst>(Val);
 165     if (!EVI)
 166       continue;
 167     if (EVI->getNumIndices() != 1)
 168       continue;
 169     if (*EVI->idx_begin() == 0)
 170       EVI->replaceAllUsesWith(ExnVal);
 171     else if (*EVI->idx_begin() == 1)
 172       EVI->replaceAllUsesWith(SelVal);
 173     if (EVI->use_empty())
 174       EVI->eraseFromParent();
 175   }
 176
 177   if (LPI->use_empty())
 178     return;
 179
 180   // There are still some uses of LPI. Construct an aggregate with the exception
 181   // values and replace the LPI with that aggregate.
 182   Type *LPadType = LPI->getType();
 183   Value *LPadVal = PoisonValue::get(LPadType);
 184   auto *SelI = cast<Instruction>(SelVal);
 185   IRBuilder<> Builder(SelI->getParent(), std::next(SelI->getIterator()));
 186   LPadVal = Builder.CreateInsertValue(LPadVal, ExnVal, 0, "lpad.val");
 187   LPadVal = Builder.CreateInsertValue(LPadVal, SelVal, 1, "lpad.val");
 188
 189   LPI->replaceAllUsesWith(LPadVal);
 190 }
 191
 192 /// setupFunctionContext - Allocate the function context on the stack and fill
 193 /// it with all of the data that we know at this point.
 194 Value *
 195 SjLjEHPrepareImpl::setupFunctionContext(Function &F,
 196                                         ArrayRef<LandingPadInst *> LPads) {
 197   BasicBlock *EntryBB = &F.front();
 198
 199   // Create an alloca for the incoming jump buffer ptr and the new jump buffer
 200   // that needs to be restored on all exits from the function. This is an alloca
 201   // because the value needs to be added to the global context list.
 202   auto &DL = F.getDataLayout();
 203   const Align Alignment = DL.getPrefTypeAlign(FunctionContextTy);
 204   FuncCtx = new AllocaInst(FunctionContextTy, DL.getAllocaAddrSpace(), nullptr,
 205                            Alignment, "fn_context", EntryBB->begin());
 206
 207   // Fill in the function context structure.
 208   for (LandingPadInst *LPI : LPads) {
 209     IRBuilder<> Builder(LPI->getParent(),
 210                         LPI->getParent()->getFirstInsertionPt());
 211
 212     // Reference the __data field.
 213     Value *FCData =
 214         Builder.CreateConstGEP2_32(FunctionContextTy, FuncCtx, 0, 2, "__data");
 215
 216     // The exception values come back in context->__data[0].
 217     Value *ExceptionAddr = Builder.CreateConstGEP2_32(doubleUnderDataTy, FCData,
 218                                                       0, 0, "exception_gep");
 219     Value *ExnVal = Builder.CreateLoad(DataTy, ExceptionAddr, true, "exn_val");
 220     ExnVal = Builder.CreateIntToPtr(ExnVal, Builder.getPtrTy());
 221
 222     Value *SelectorAddr = Builder.CreateConstGEP2_32(doubleUnderDataTy, FCData,
 223                                                      0, 1, "exn_selector_gep");
 224     Value *SelVal =
 225         Builder.CreateLoad(DataTy, SelectorAddr, true, "exn_selector_val");
 226
 227     // SelVal must be Int32Ty, so trunc it
 228     SelVal = Builder.CreateTrunc(SelVal, Type::getInt32Ty(F.getContext()));
 229
 230     substituteLPadValues(LPI, ExnVal, SelVal);
 231   }
 232
 233   // Personality function
 234   IRBuilder<> Builder(EntryBB->getTerminator());
 235   Value *PersonalityFn = F.getPersonalityFn();
 236   Value *PersonalityFieldPtr = Builder.CreateConstGEP2_32(
 237       FunctionContextTy, FuncCtx, 0, 3, "pers_fn_gep");
 238   Builder.CreateStore(PersonalityFn, PersonalityFieldPtr, /*isVolatile=*/true);
 239
 240   // LSDA address
 241   Value *LSDA = Builder.CreateCall(LSDAAddrFn, {}, "lsda_addr");
 242   Value *LSDAFieldPtr =
 243       Builder.CreateConstGEP2_32(FunctionContextTy, FuncCtx, 0, 4, "lsda_gep");
 244   Builder.CreateStore(LSDA, LSDAFieldPtr, /*isVolatile=*/true);
 245
 246   return FuncCtx;
 247 }
 248
 249 /// lowerIncomingArguments - To avoid having to handle incoming arguments
 250 /// specially, we lower each arg to a copy instruction in the entry block. This
 251 /// ensures that the argument value itself cannot be live out of the entry
 252 /// block.
 253 void SjLjEHPrepareImpl::lowerIncomingArguments(Function &F) {
 254   BasicBlock::iterator AfterAllocaInsPt = F.begin()->begin();
 255   while (isa<AllocaInst>(AfterAllocaInsPt) &&
 256          cast<AllocaInst>(AfterAllocaInsPt)->isStaticAlloca())
 257     ++AfterAllocaInsPt;
 258   assert(AfterAllocaInsPt != F.front().end());
 259
 260   for (auto &AI : F.args()) {
 261     // Swift error really is a register that we model as memory -- instruction
 262     // selection will perform mem-to-reg for us and spill/reload appropriately
 263     // around calls that clobber it. There is no need to spill this
 264     // value to the stack and doing so would not be allowed.
 265     if (AI.isSwiftError())
 266       continue;
 267
 268     Type *Ty = AI.getType();
 269
 270     // Use 'select i8 true, %arg, undef' to simulate a 'no-op' instruction.
 271     Value *TrueValue = ConstantInt::getTrue(F.getContext());
 272     Value *UndefValue = UndefValue::get(Ty);
 273     Instruction *SI = SelectInst::Create(
 274         TrueValue, &AI, UndefValue, AI.getName() + ".tmp", AfterAllocaInsPt);
 275     AI.replaceAllUsesWith(SI);
 276
 277     // Reset the operand, because it  was clobbered by the RAUW above.
 278     SI->setOperand(1, &AI);
 279   }
 280 }
 281
 282 /// lowerAcrossUnwindEdges - Find all variables which are alive across an unwind
 283 /// edge and spill them.
 284 void SjLjEHPrepareImpl::lowerAcrossUnwindEdges(Function &F,
 285                                                ArrayRef<InvokeInst *> Invokes) {
 286   // Finally, scan the code looking for instructions with bad live ranges.
 287   for (BasicBlock &BB : F) {
 288     for (Instruction &Inst : BB) {
 289       // Ignore obvious cases we don't have to handle. In particular, most
 290       // instructions either have no uses or only have a single use inside the
 291       // current block. Ignore them quickly.
 292       if (Inst.use_empty())
 293         continue;
 294       if (Inst.hasOneUse() &&
 295           cast<Instruction>(Inst.user_back())->getParent() == &BB &&
 296           !isa<PHINode>(Inst.user_back()))
 297         continue;
 298
 299       // If this is an alloca in the entry block, it's not a real register
 300       // value.
 301       if (auto *AI = dyn_cast<AllocaInst>(&Inst))
 302         if (AI->isStaticAlloca())
 303           continue;
 304
 305       // Avoid iterator invalidation by copying users to a temporary vector.
 306       SmallVector<Instruction *, 16> Users;
 307       for (User *U : Inst.users()) {
 308         Instruction *UI = cast<Instruction>(U);
 309         if (UI->getParent() != &BB || isa<PHINode>(UI))
 310           Users.push_back(UI);
 311       }
 312
 313       // Find all of the blocks that this value is live in.
 314       SmallPtrSet<BasicBlock *, 32> LiveBBs;
 315       LiveBBs.insert(&BB);
 316       while (!Users.empty()) {
 317         Instruction *U = Users.pop_back_val();
 318
 319         if (!isa<PHINode>(U)) {
 320           MarkBlocksLiveIn(U->getParent(), LiveBBs);
 321         } else {
 322           // Uses for a PHI node occur in their predecessor block.
 323           PHINode *PN = cast<PHINode>(U);
 324           for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
 325             if (PN->getIncomingValue(i) == &Inst)
 326               MarkBlocksLiveIn(PN->getIncomingBlock(i), LiveBBs);
 327         }
 328       }
 329
 330       // Now that we know all of the blocks that this thing is live in, see if
 331       // it includes any of the unwind locations.
 332       bool NeedsSpill = false;
 333       for (InvokeInst *Invoke : Invokes) {
 334         BasicBlock *UnwindBlock = Invoke->getUnwindDest();
 335         if (UnwindBlock != &BB && LiveBBs.count(UnwindBlock)) {
 336           LLVM_DEBUG(dbgs() << "SJLJ Spill: " << Inst << " around "
 337                             << UnwindBlock->getName() << "\n");
 338           NeedsSpill = true;
 339           break;
 340         }
 341       }
 342
 343       // If we decided we need a spill, do it.
 344       // FIXME: Spilling this way is overkill, as it forces all uses of
 345       // the value to be reloaded from the stack slot, even those that aren't
 346       // in the unwind blocks. We should be more selective.
 347       if (NeedsSpill) {
 348         DemoteRegToStack(Inst, true);
 349         ++NumSpilled;
 350       }
 351     }
 352   }
 353
 354   // Go through the landing pads and remove any PHIs there.
 355   for (InvokeInst *Invoke : Invokes) {
 356     BasicBlock *UnwindBlock = Invoke->getUnwindDest();
 357     LandingPadInst *LPI = UnwindBlock->getLandingPadInst();
 358
 359     // Place PHIs into a set to avoid invalidating the iterator.
 360     SmallPtrSet<PHINode *, 8> PHIsToDemote;
 361     for (BasicBlock::iterator PN = UnwindBlock->begin(); isa<PHINode>(PN); ++PN)
 362       PHIsToDemote.insert(cast<PHINode>(PN));
 363     if (PHIsToDemote.empty())
 364       continue;
 365
 366     // Demote the PHIs to the stack.
 367     for (PHINode *PN : PHIsToDemote)
 368       DemotePHIToStack(PN);
 369
 370     // Move the landingpad instruction back to the top of the landing pad block.
 371     LPI->moveBefore(&UnwindBlock->front());
 372   }
 373 }
 374
 375 /// setupEntryBlockAndCallSites - Setup the entry block by creating and filling
 376 /// the function context and marking the call sites with the appropriate
 377 /// values. These values are used by the DWARF EH emitter.
 378 bool SjLjEHPrepareImpl::setupEntryBlockAndCallSites(Function &F) {
 379   SmallVector<ReturnInst *, 16> Returns;
 380   SmallVector<InvokeInst *, 16> Invokes;
 381   SmallSetVector<LandingPadInst *, 16> LPads;
 382
 383   // Look through the terminators of the basic blocks to find invokes.
 384   for (BasicBlock &BB : F)
 385     if (auto *II = dyn_cast<InvokeInst>(BB.getTerminator())) {
 386       if (Function *Callee = II->getCalledFunction())
 387         if (Callee->getIntrinsicID() == Intrinsic::donothing) {
 388           // Remove the NOP invoke.
 389           BranchInst::Create(II->getNormalDest(), II->getIterator());
 390           II->eraseFromParent();
 391           continue;
 392         }
 393
 394       Invokes.push_back(II);
 395       LPads.insert(II->getUnwindDest()->getLandingPadInst());
 396     } else if (auto *RI = dyn_cast<ReturnInst>(BB.getTerminator())) {
 397       Returns.push_back(RI);
 398     }
 399
 400   if (Invokes.empty())
 401     return false;
 402
 403   NumInvokes += Invokes.size();
 404
 405   lowerIncomingArguments(F);
 406   lowerAcrossUnwindEdges(F, Invokes);
 407
 408   Value *FuncCtx =
 409       setupFunctionContext(F, ArrayRef(LPads.begin(), LPads.end()));
 410   BasicBlock *EntryBB = &F.front();
 411   IRBuilder<> Builder(EntryBB->getTerminator());
 412
 413   // Get a reference to the jump buffer.
 414   Value *JBufPtr =
 415       Builder.CreateConstGEP2_32(FunctionContextTy, FuncCtx, 0, 5, "jbuf_gep");
 416
 417   // Save the frame pointer.
 418   Value *FramePtr = Builder.CreateConstGEP2_32(doubleUnderJBufTy, JBufPtr, 0, 0,
 419                                                "jbuf_fp_gep");
 420
 421   Value *Val = Builder.CreateCall(FrameAddrFn, Builder.getInt32(0), "fp");
 422   Builder.CreateStore(Val, FramePtr, /*isVolatile=*/true);
 423
 424   // Save the stack pointer.
 425   Value *StackPtr = Builder.CreateConstGEP2_32(doubleUnderJBufTy, JBufPtr, 0, 2,
 426                                                "jbuf_sp_gep");
 427
 428   Val = Builder.CreateCall(StackAddrFn, {}, "sp");
 429   Builder.CreateStore(Val, StackPtr, /*isVolatile=*/true);
 430
 431   // Call the setup_dispatch intrinsic. It fills in the rest of the jmpbuf.
 432   Builder.CreateCall(BuiltinSetupDispatchFn, {});
 433
 434   // Store a pointer to the function context so that the back-end will know
 435   // where to look for it.
 436   Builder.CreateCall(FuncCtxFn, FuncCtx);
 437
 438   // At this point, we are all set up, update the invoke instructions to mark
 439   // their call_site values.
 440   for (unsigned I = 0, E = Invokes.size(); I != E; ++I) {
 441     insertCallSiteStore(Invokes[I], I + 1);
 442
 443     ConstantInt *CallSiteNum =
 444         ConstantInt::get(Type::getInt32Ty(F.getContext()), I + 1);
 445
 446     // Record the call site value for the back end so it stays associated with
 447     // the invoke.
 448     CallInst::Create(CallSiteFn, CallSiteNum, "", Invokes[I]->getIterator());
 449   }
 450
 451   // Mark call instructions that aren't nounwind as no-action (call_site ==
 452   // -1). Skip the entry block, as prior to then, no function context has been
 453   // created for this function and any unexpected exceptions thrown will go
 454   // directly to the caller's context, which is what we want anyway, so no need
 455   // to do anything here.
 456   for (BasicBlock &BB : F) {
 457     if (&BB == &F.front())
 458       continue;
 459     for (Instruction &I : BB)
 460       if (I.mayThrow())
 461         insertCallSiteStore(&I, -1);
 462   }
 463
 464   // Register the function context and make sure it's known to not throw
 465   CallInst *Register = CallInst::Create(
 466       RegisterFn, FuncCtx, "", EntryBB->getTerminator()->getIterator());
 467   Register->setDoesNotThrow();
 468
 469   // Following any allocas not in the entry block, update the saved SP in the
 470   // jmpbuf to the new value.
 471   for (BasicBlock &BB : F) {
 472     if (&BB == &F.front())
 473       continue;
 474     for (Instruction &I : BB) {
 475       if (auto *CI = dyn_cast<CallInst>(&I)) {
 476         if (CI->getCalledFunction() != StackRestoreFn)
 477           continue;
 478       } else if (!isa<AllocaInst>(&I)) {
 479         continue;
 480       }
 481       Instruction *StackAddr = CallInst::Create(StackAddrFn, "sp");
 482       StackAddr->insertAfter(&I);
 483       new StoreInst(StackAddr, StackPtr, true,
 484                     std::next(StackAddr->getIterator()));
 485     }
 486   }
 487
 488   // Finally, for any returns from this function, if this function contains an
 489   // invoke, add a call to unregister the function context.
 490   for (ReturnInst *Return : Returns) {
 491     Instruction *InsertPoint = Return;
 492     if (CallInst *CI = Return->getParent()->getTerminatingMustTailCall())
 493       InsertPoint = CI;
 494     CallInst::Create(UnregisterFn, FuncCtx, "", InsertPoint->getIterator());
 495   }
 496
 497   return true;
 498 }
 499
 500 bool SjLjEHPrepareImpl::runOnFunction(Function &F) {
 501   Module &M = *F.getParent();
 502   RegisterFn = M.getOrInsertFunction(
 503       "_Unwind_SjLj_Register", Type::getVoidTy(M.getContext()),
 504       PointerType::getUnqual(FunctionContextTy));
 505   UnregisterFn = M.getOrInsertFunction(
 506       "_Unwind_SjLj_Unregister", Type::getVoidTy(M.getContext()),
 507       PointerType::getUnqual(FunctionContextTy));
 508
 509   PointerType *AllocaPtrTy = M.getDataLayout().getAllocaPtrType(M.getContext());
 510
 511   FrameAddrFn =
 512       Intrinsic::getDeclaration(&M, Intrinsic::frameaddress, {AllocaPtrTy});
 513   StackAddrFn =
 514       Intrinsic::getDeclaration(&M, Intrinsic::stacksave, {AllocaPtrTy});
 515   StackRestoreFn =
 516       Intrinsic::getDeclaration(&M, Intrinsic::stackrestore, {AllocaPtrTy});
 517   BuiltinSetupDispatchFn =
 518     Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_setup_dispatch);
 519   LSDAAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_lsda);
 520   CallSiteFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_callsite);
 521   FuncCtxFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_functioncontext);
 522
 523   bool Res = setupEntryBlockAndCallSites(F);
 524   return Res;
 525 }