LCOV - code coverage report
Current view: top level - lib/CodeGen - SjLjEHPrepare.cpp (source / functions) Hit Total Coverage
Test: llvm-toolchain.info Lines: 171 184 92.9 %
Date: 2018-07-13 00:08:38 Functions: 14 16 87.5 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : //===- SjLjEHPrepare.cpp - Eliminate Invoke & Unwind instructions ---------===//
       2             : //
       3             : //                     The LLVM Compiler Infrastructure
       4             : //
       5             : // This file is distributed under the University of Illinois Open Source
       6             : // License. See LICENSE.TXT for details.
       7             : //
       8             : //===----------------------------------------------------------------------===//
       9             : //
      10             : // This transformation is designed for use by code generators which use SjLj
      11             : // based exception handling.
      12             : //
      13             : //===----------------------------------------------------------------------===//
      14             : 
      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/Transforms/Utils/Local.h"
      20             : #include "llvm/CodeGen/Passes.h"
      21             : #include "llvm/IR/Constants.h"
      22             : #include "llvm/IR/DataLayout.h"
      23             : #include "llvm/IR/DerivedTypes.h"
      24             : #include "llvm/IR/IRBuilder.h"
      25             : #include "llvm/IR/Instructions.h"
      26             : #include "llvm/IR/Intrinsics.h"
      27             : #include "llvm/IR/Module.h"
      28             : #include "llvm/Pass.h"
      29             : #include "llvm/Support/Debug.h"
      30             : #include "llvm/Support/raw_ostream.h"
      31             : using namespace llvm;
      32             : 
      33             : #define DEBUG_TYPE "sjljehprepare"
      34             : 
      35             : STATISTIC(NumInvokes, "Number of invokes replaced");
      36             : STATISTIC(NumSpilled, "Number of registers live across unwind edges");
      37             : 
      38             : namespace {
      39        1424 : class SjLjEHPrepare : public FunctionPass {
      40             :   Type *doubleUnderDataTy;
      41             :   Type *doubleUnderJBufTy;
      42             :   Type *FunctionContextTy;
      43             :   Constant *RegisterFn;
      44             :   Constant *UnregisterFn;
      45             :   Constant *BuiltinSetupDispatchFn;
      46             :   Constant *FrameAddrFn;
      47             :   Constant *StackAddrFn;
      48             :   Constant *StackRestoreFn;
      49             :   Constant *LSDAAddrFn;
      50             :   Constant *CallSiteFn;
      51             :   Constant *FuncCtxFn;
      52             :   AllocaInst *FuncCtx;
      53             : 
      54             : public:
      55             :   static char ID; // Pass identification, replacement for typeid
      56        1428 :   explicit SjLjEHPrepare() : FunctionPass(ID) {}
      57             :   bool doInitialization(Module &M) override;
      58             :   bool runOnFunction(Function &F) override;
      59             : 
      60         711 :   void getAnalysisUsage(AnalysisUsage &AU) const override {}
      61           0 :   StringRef getPassName() const override {
      62           0 :     return "SJLJ Exception Handling preparation";
      63             :   }
      64             : 
      65             : private:
      66             :   bool setupEntryBlockAndCallSites(Function &F);
      67             :   void substituteLPadValues(LandingPadInst *LPI, Value *ExnVal, Value *SelVal);
      68             :   Value *setupFunctionContext(Function &F, ArrayRef<LandingPadInst *> LPads);
      69             :   void lowerIncomingArguments(Function &F);
      70             :   void lowerAcrossUnwindEdges(Function &F, ArrayRef<InvokeInst *> Invokes);
      71             :   void insertCallSiteStore(Instruction *I, int Number);
      72             : };
      73             : } // end anonymous namespace
      74             : 
      75             : char SjLjEHPrepare::ID = 0;
      76       41520 : INITIALIZE_PASS(SjLjEHPrepare, DEBUG_TYPE, "Prepare SjLj exceptions",
      77             :                 false, false)
      78             : 
      79             : // Public Interface To the SjLjEHPrepare pass.
      80        1424 : FunctionPass *llvm::createSjLjEHPreparePass() { return new SjLjEHPrepare(); }
      81             : // doInitialization - Set up decalarations and types needed to process
      82             : // exceptions.
      83         711 : bool SjLjEHPrepare::doInitialization(Module &M) {
      84             :   // Build the function context structure.
      85             :   // builtin_setjmp uses a five word jbuf
      86         711 :   Type *VoidPtrTy = Type::getInt8PtrTy(M.getContext());
      87         711 :   Type *Int32Ty = Type::getInt32Ty(M.getContext());
      88         711 :   doubleUnderDataTy = ArrayType::get(Int32Ty, 4);
      89         711 :   doubleUnderJBufTy = ArrayType::get(VoidPtrTy, 5);
      90         711 :   FunctionContextTy = StructType::get(VoidPtrTy,         // __prev
      91             :                                       Int32Ty,           // call_site
      92             :                                       doubleUnderDataTy, // __data
      93             :                                       VoidPtrTy,         // __personality
      94             :                                       VoidPtrTy,         // __lsda
      95             :                                       doubleUnderJBufTy  // __jbuf
      96             :                                       );
      97             : 
      98         711 :   return true;
      99             : }
     100             : 
     101             : /// insertCallSiteStore - Insert a store of the call-site value to the
     102             : /// function context
     103         964 : void SjLjEHPrepare::insertCallSiteStore(Instruction *I, int Number) {
     104         964 :   IRBuilder<> Builder(I);
     105             : 
     106             :   // Get a reference to the call_site field.
     107         964 :   Type *Int32Ty = Type::getInt32Ty(I->getContext());
     108         964 :   Value *Zero = ConstantInt::get(Int32Ty, 0);
     109         964 :   Value *One = ConstantInt::get(Int32Ty, 1);
     110         964 :   Value *Idxs[2] = { Zero, One };
     111             :   Value *CallSite =
     112         964 :       Builder.CreateGEP(FunctionContextTy, FuncCtx, Idxs, "call_site");
     113             : 
     114             :   // Insert a store of the call-site number
     115             :   ConstantInt *CallSiteNoC =
     116         964 :       ConstantInt::get(Type::getInt32Ty(I->getContext()), Number);
     117         964 :   Builder.CreateStore(CallSiteNoC, CallSite, true /*volatile*/);
     118         964 : }
     119             : 
     120             : /// MarkBlocksLiveIn - Insert BB and all of its predecessors into LiveBBs until
     121             : /// we reach blocks we've already seen.
     122         612 : static void MarkBlocksLiveIn(BasicBlock *BB,
     123             :                              SmallPtrSetImpl<BasicBlock *> &LiveBBs) {
     124         612 :   if (!LiveBBs.insert(BB).second)
     125         322 :     return; // already been here.
     126             : 
     127             :   df_iterator_default_set<BasicBlock*> Visited;
     128             : 
     129        8314 :   for (BasicBlock *B : inverse_depth_first_ext(BB, Visited))
     130        3722 :     LiveBBs.insert(B);
     131             : 
     132             : }
     133             : 
     134             : /// substituteLPadValues - Substitute the values returned by the landingpad
     135             : /// instruction with those returned by the personality function.
     136         131 : void SjLjEHPrepare::substituteLPadValues(LandingPadInst *LPI, Value *ExnVal,
     137             :                                          Value *SelVal) {
     138         131 :   SmallVector<Value *, 8> UseWorkList(LPI->user_begin(), LPI->user_end());
     139         341 :   while (!UseWorkList.empty()) {
     140             :     Value *Val = UseWorkList.pop_back_val();
     141             :     auto *EVI = dyn_cast<ExtractValueInst>(Val);
     142           9 :     if (!EVI)
     143             :       continue;
     144         201 :     if (EVI->getNumIndices() != 1)
     145             :       continue;
     146         201 :     if (*EVI->idx_begin() == 0)
     147         106 :       EVI->replaceAllUsesWith(ExnVal);
     148          95 :     else if (*EVI->idx_begin() == 1)
     149          95 :       EVI->replaceAllUsesWith(SelVal);
     150         201 :     if (EVI->use_empty())
     151         201 :       EVI->eraseFromParent();
     152             :   }
     153             : 
     154         131 :   if (LPI->use_empty())
     155             :     return;
     156             : 
     157             :   // There are still some uses of LPI. Construct an aggregate with the exception
     158             :   // values and replace the LPI with that aggregate.
     159           9 :   Type *LPadType = LPI->getType();
     160           9 :   Value *LPadVal = UndefValue::get(LPadType);
     161             :   auto *SelI = cast<Instruction>(SelVal);
     162          18 :   IRBuilder<> Builder(SelI->getParent(), std::next(SelI->getIterator()));
     163          18 :   LPadVal = Builder.CreateInsertValue(LPadVal, ExnVal, 0, "lpad.val");
     164          18 :   LPadVal = Builder.CreateInsertValue(LPadVal, SelVal, 1, "lpad.val");
     165             : 
     166           9 :   LPI->replaceAllUsesWith(LPadVal);
     167             : }
     168             : 
     169             : /// setupFunctionContext - Allocate the function context on the stack and fill
     170             : /// it with all of the data that we know at this point.
     171          39 : Value *SjLjEHPrepare::setupFunctionContext(Function &F,
     172             :                                            ArrayRef<LandingPadInst *> LPads) {
     173             :   BasicBlock *EntryBB = &F.front();
     174             : 
     175             :   // Create an alloca for the incoming jump buffer ptr and the new jump buffer
     176             :   // that needs to be restored on all exits from the function. This is an alloca
     177             :   // because the value needs to be added to the global context list.
     178          39 :   auto &DL = F.getParent()->getDataLayout();
     179          39 :   unsigned Align = DL.getPrefTypeAlignment(FunctionContextTy);
     180          78 :   FuncCtx = new AllocaInst(FunctionContextTy, DL.getAllocaAddrSpace(),
     181          39 :                            nullptr, Align, "fn_context", &EntryBB->front());
     182             : 
     183             :   // Fill in the function context structure.
     184         301 :   for (LandingPadInst *LPI : LPads) {
     185             :     IRBuilder<> Builder(LPI->getParent(),
     186         262 :                         LPI->getParent()->getFirstInsertionPt());
     187             : 
     188             :     // Reference the __data field.
     189             :     Value *FCData =
     190         131 :         Builder.CreateConstGEP2_32(FunctionContextTy, FuncCtx, 0, 2, "__data");
     191             : 
     192             :     // The exception values come back in context->__data[0].
     193         262 :     Value *ExceptionAddr = Builder.CreateConstGEP2_32(doubleUnderDataTy, FCData,
     194         131 :                                                       0, 0, "exception_gep");
     195         131 :     Value *ExnVal = Builder.CreateLoad(ExceptionAddr, true, "exn_val");
     196         262 :     ExnVal = Builder.CreateIntToPtr(ExnVal, Builder.getInt8PtrTy());
     197             : 
     198         262 :     Value *SelectorAddr = Builder.CreateConstGEP2_32(doubleUnderDataTy, FCData,
     199         131 :                                                      0, 1, "exn_selector_gep");
     200         131 :     Value *SelVal = Builder.CreateLoad(SelectorAddr, true, "exn_selector_val");
     201             : 
     202         131 :     substituteLPadValues(LPI, ExnVal, SelVal);
     203             :   }
     204             : 
     205             :   // Personality function
     206          39 :   IRBuilder<> Builder(EntryBB->getTerminator());
     207          39 :   Value *PersonalityFn = F.getPersonalityFn();
     208          78 :   Value *PersonalityFieldPtr = Builder.CreateConstGEP2_32(
     209          78 :       FunctionContextTy, FuncCtx, 0, 3, "pers_fn_gep");
     210          39 :   Builder.CreateStore(
     211          39 :       Builder.CreateBitCast(PersonalityFn, Builder.getInt8PtrTy()),
     212             :       PersonalityFieldPtr, /*isVolatile=*/true);
     213             : 
     214             :   // LSDA address
     215          78 :   Value *LSDA = Builder.CreateCall(LSDAAddrFn, {}, "lsda_addr");
     216             :   Value *LSDAFieldPtr =
     217          39 :       Builder.CreateConstGEP2_32(FunctionContextTy, FuncCtx, 0, 4, "lsda_gep");
     218          39 :   Builder.CreateStore(LSDA, LSDAFieldPtr, /*isVolatile=*/true);
     219             : 
     220          78 :   return FuncCtx;
     221             : }
     222             : 
     223             : /// lowerIncomingArguments - To avoid having to handle incoming arguments
     224             : /// specially, we lower each arg to a copy instruction in the entry block. This
     225             : /// ensures that the argument value itself cannot be live out of the entry
     226             : /// block.
     227          39 : void SjLjEHPrepare::lowerIncomingArguments(Function &F) {
     228             :   BasicBlock::iterator AfterAllocaInsPt = F.begin()->begin();
     229        1517 :   while (isa<AllocaInst>(AfterAllocaInsPt) &&
     230         739 :          cast<AllocaInst>(AfterAllocaInsPt)->isStaticAlloca())
     231             :     ++AfterAllocaInsPt;
     232             :   assert(AfterAllocaInsPt != F.front().end());
     233             : 
     234          81 :   for (auto &AI : F.args()) {
     235             :     // Swift error really is a register that we model as memory -- instruction
     236             :     // selection will perform mem-to-reg for us and spill/reload appropriately
     237             :     // around calls that clobber it. There is no need to spill this
     238             :     // value to the stack and doing so would not be allowed.
     239          42 :     if (AI.isSwiftError())
     240             :       continue;
     241             : 
     242          40 :     Type *Ty = AI.getType();
     243             : 
     244             :     // Use 'select i8 true, %arg, undef' to simulate a 'no-op' instruction.
     245          40 :     Value *TrueValue = ConstantInt::getTrue(F.getContext());
     246          40 :     Value *UndefValue = UndefValue::get(Ty);
     247             :     Instruction *SI = SelectInst::Create(
     248          80 :         TrueValue, &AI, UndefValue, AI.getName() + ".tmp", &*AfterAllocaInsPt);
     249          40 :     AI.replaceAllUsesWith(SI);
     250             : 
     251             :     // Reset the operand, because it  was clobbered by the RAUW above.
     252          40 :     SI->setOperand(1, &AI);
     253             :   }
     254          39 : }
     255             : 
     256             : /// lowerAcrossUnwindEdges - Find all variables which are alive across an unwind
     257             : /// edge and spill them.
     258          39 : void SjLjEHPrepare::lowerAcrossUnwindEdges(Function &F,
     259             :                                            ArrayRef<InvokeInst *> Invokes) {
     260             :   // Finally, scan the code looking for instructions with bad live ranges.
     261         419 :   for (BasicBlock &BB : F) {
     262        5778 :     for (Instruction &Inst : BB) {
     263             :       // Ignore obvious cases we don't have to handle. In particular, most
     264             :       // instructions either have no uses or only have a single use inside the
     265             :       // current block. Ignore them quickly.
     266        5398 :       if (Inst.use_empty())
     267        5092 :         continue;
     268        4328 :       if (Inst.hasOneUse() &&
     269        7519 :           cast<Instruction>(Inst.user_back())->getParent() == &BB &&
     270             :           !isa<PHINode>(Inst.user_back()))
     271             :         continue;
     272             : 
     273             :       // If this is an alloca in the entry block, it's not a real register
     274             :       // value.
     275             :       if (auto *AI = dyn_cast<AllocaInst>(&Inst))
     276         733 :         if (AI->isStaticAlloca())
     277             :           continue;
     278             : 
     279             :       // Avoid iterator invalidation by copying users to a temporary vector.
     280             :       SmallVector<Instruction *, 16> Users;
     281        1341 :       for (User *U : Inst.users()) {
     282        1035 :         Instruction *UI = cast<Instruction>(U);
     283        1464 :         if (UI->getParent() != &BB || isa<PHINode>(UI))
     284         606 :           Users.push_back(UI);
     285             :       }
     286             : 
     287             :       // Find all of the blocks that this value is live in.
     288             :       SmallPtrSet<BasicBlock *, 32> LiveBBs;
     289         306 :       LiveBBs.insert(&BB);
     290         912 :       while (!Users.empty()) {
     291             :         Instruction *U = Users.pop_back_val();
     292             : 
     293         606 :         if (!isa<PHINode>(U)) {
     294         585 :           MarkBlocksLiveIn(U->getParent(), LiveBBs);
     295             :         } else {
     296             :           // Uses for a PHI node occur in their predecessor block.
     297             :           PHINode *PN = cast<PHINode>(U);
     298         127 :           for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
     299          53 :             if (PN->getIncomingValue(i) == &Inst)
     300          27 :               MarkBlocksLiveIn(PN->getIncomingBlock(i), LiveBBs);
     301             :         }
     302             :       }
     303             : 
     304             :       // Now that we know all of the blocks that this thing is live in, see if
     305             :       // it includes any of the unwind locations.
     306             :       bool NeedsSpill = false;
     307       13996 :       for (InvokeInst *Invoke : Invokes) {
     308             :         BasicBlock *UnwindBlock = Invoke->getUnwindDest();
     309        6937 :         if (UnwindBlock != &BB && LiveBBs.count(UnwindBlock)) {
     310             :           LLVM_DEBUG(dbgs() << "SJLJ Spill: " << Inst << " around "
     311             :                             << UnwindBlock->getName() << "\n");
     312             :           NeedsSpill = true;
     313             :           break;
     314             :         }
     315             :       }
     316             : 
     317             :       // If we decided we need a spill, do it.
     318             :       // FIXME: Spilling this way is overkill, as it forces all uses of
     319             :       // the value to be reloaded from the stack slot, even those that aren't
     320             :       // in the unwind blocks. We should be more selective.
     321         306 :       if (NeedsSpill) {
     322          92 :         DemoteRegToStack(Inst, true);
     323             :         ++NumSpilled;
     324             :       }
     325             :     }
     326             :   }
     327             : 
     328             :   // Go through the landing pads and remove any PHIs there.
     329         395 :   for (InvokeInst *Invoke : Invokes) {
     330             :     BasicBlock *UnwindBlock = Invoke->getUnwindDest();
     331             :     LandingPadInst *LPI = UnwindBlock->getLandingPadInst();
     332             : 
     333             :     // Place PHIs into a set to avoid invalidating the iterator.
     334             :     SmallPtrSet<PHINode *, 8> PHIsToDemote;
     335         178 :     for (BasicBlock::iterator PN = UnwindBlock->begin(); isa<PHINode>(PN); ++PN)
     336           0 :       PHIsToDemote.insert(cast<PHINode>(PN));
     337         178 :     if (PHIsToDemote.empty())
     338             :       continue;
     339             : 
     340             :     // Demote the PHIs to the stack.
     341           0 :     for (PHINode *PN : PHIsToDemote)
     342           0 :       DemotePHIToStack(PN);
     343             : 
     344             :     // Move the landingpad instruction back to the top of the landing pad block.
     345           0 :     LPI->moveBefore(&UnwindBlock->front());
     346             :   }
     347          39 : }
     348             : 
     349             : /// setupEntryBlockAndCallSites - Setup the entry block by creating and filling
     350             : /// the function context and marking the call sites with the appropriate
     351             : /// values. These values are used by the DWARF EH emitter.
     352        2299 : bool SjLjEHPrepare::setupEntryBlockAndCallSites(Function &F) {
     353             :   SmallVector<ReturnInst *, 16> Returns;
     354             :   SmallVector<InvokeInst *, 16> Invokes;
     355             :   SmallSetVector<LandingPadInst *, 16> LPads;
     356             : 
     357             :   // Look through the terminators of the basic blocks to find invokes.
     358        6608 :   for (BasicBlock &BB : F)
     359        4309 :     if (auto *II = dyn_cast<InvokeInst>(BB.getTerminator())) {
     360             :       if (Function *Callee = II->getCalledFunction())
     361         175 :         if (Callee->getIntrinsicID() == Intrinsic::donothing) {
     362             :           // Remove the NOP invoke.
     363           0 :           BranchInst::Create(II->getNormalDest(), II);
     364           0 :           II->eraseFromParent();
     365           0 :           continue;
     366             :         }
     367             : 
     368         178 :       Invokes.push_back(II);
     369         356 :       LPads.insert(II->getUnwindDest()->getLandingPadInst());
     370        4131 :     } else if (auto *RI = dyn_cast<ReturnInst>(BB.getTerminator())) {
     371        2349 :       Returns.push_back(RI);
     372             :     }
     373             : 
     374        2299 :   if (Invokes.empty())
     375             :     return false;
     376             : 
     377             :   NumInvokes += Invokes.size();
     378             : 
     379          39 :   lowerIncomingArguments(F);
     380          39 :   lowerAcrossUnwindEdges(F, Invokes);
     381             : 
     382             :   Value *FuncCtx =
     383          39 :       setupFunctionContext(F, makeArrayRef(LPads.begin(), LPads.end()));
     384             :   BasicBlock *EntryBB = &F.front();
     385          39 :   IRBuilder<> Builder(EntryBB->getTerminator());
     386             : 
     387             :   // Get a reference to the jump buffer.
     388             :   Value *JBufPtr =
     389          39 :       Builder.CreateConstGEP2_32(FunctionContextTy, FuncCtx, 0, 5, "jbuf_gep");
     390             : 
     391             :   // Save the frame pointer.
     392          78 :   Value *FramePtr = Builder.CreateConstGEP2_32(doubleUnderJBufTy, JBufPtr, 0, 0,
     393          39 :                                                "jbuf_fp_gep");
     394             : 
     395          78 :   Value *Val = Builder.CreateCall(FrameAddrFn, Builder.getInt32(0), "fp");
     396          39 :   Builder.CreateStore(Val, FramePtr, /*isVolatile=*/true);
     397             : 
     398             :   // Save the stack pointer.
     399          78 :   Value *StackPtr = Builder.CreateConstGEP2_32(doubleUnderJBufTy, JBufPtr, 0, 2,
     400          39 :                                                "jbuf_sp_gep");
     401             : 
     402          78 :   Val = Builder.CreateCall(StackAddrFn, {}, "sp");
     403          39 :   Builder.CreateStore(Val, StackPtr, /*isVolatile=*/true);
     404             : 
     405             :   // Call the setup_dispatch instrinsic. It fills in the rest of the jmpbuf.
     406          78 :   Builder.CreateCall(BuiltinSetupDispatchFn, {});
     407             : 
     408             :   // Store a pointer to the function context so that the back-end will know
     409             :   // where to look for it.
     410         117 :   Value *FuncCtxArg = Builder.CreateBitCast(FuncCtx, Builder.getInt8PtrTy());
     411          78 :   Builder.CreateCall(FuncCtxFn, FuncCtxArg);
     412             : 
     413             :   // At this point, we are all set up, update the invoke instructions to mark
     414             :   // their call_site values.
     415         217 :   for (unsigned I = 0, E = Invokes.size(); I != E; ++I) {
     416         356 :     insertCallSiteStore(Invokes[I], I + 1);
     417             : 
     418             :     ConstantInt *CallSiteNum =
     419         178 :         ConstantInt::get(Type::getInt32Ty(F.getContext()), I + 1);
     420             : 
     421             :     // Record the call site value for the back end so it stays associated with
     422             :     // the invoke.
     423         534 :     CallInst::Create(CallSiteFn, CallSiteNum, "", Invokes[I]);
     424             :   }
     425             : 
     426             :   // Mark call instructions that aren't nounwind as no-action (call_site ==
     427             :   // -1). Skip the entry block, as prior to then, no function context has been
     428             :   // created for this function and any unexpected exceptions thrown will go
     429             :   // directly to the caller's context, which is what we want anyway, so no need
     430             :   // to do anything here.
     431         419 :   for (BasicBlock &BB : F) {
     432         380 :     if (&BB == &F.front())
     433          39 :       continue;
     434        5831 :     for (Instruction &I : BB)
     435        5490 :       if (I.mayThrow())
     436         786 :         insertCallSiteStore(&I, -1);
     437             :   }
     438             : 
     439             :   // Register the function context and make sure it's known to not throw
     440             :   CallInst *Register =
     441          78 :       CallInst::Create(RegisterFn, FuncCtx, "", EntryBB->getTerminator());
     442          39 :   Register->setDoesNotThrow();
     443             : 
     444             :   // Following any allocas not in the entry block, update the saved SP in the
     445             :   // jmpbuf to the new value.
     446         419 :   for (BasicBlock &BB : F) {
     447         380 :     if (&BB == &F.front())
     448          39 :       continue;
     449        7403 :     for (Instruction &I : BB) {
     450             :       if (auto *CI = dyn_cast<CallInst>(&I)) {
     451        1268 :         if (CI->getCalledFunction() != StackRestoreFn)
     452        1268 :           continue;
     453        5794 :       } else if (!isa<AllocaInst>(&I)) {
     454        5794 :         continue;
     455             :       }
     456           0 :       Instruction *StackAddr = CallInst::Create(StackAddrFn, "sp");
     457           0 :       StackAddr->insertAfter(&I);
     458           0 :       Instruction *StoreStackAddr = new StoreInst(StackAddr, StackPtr, true);
     459           0 :       StoreStackAddr->insertAfter(StackAddr);
     460             :     }
     461             :   }
     462             : 
     463             :   // Finally, for any returns from this function, if this function contains an
     464             :   // invoke, add a call to unregister the function context.
     465         107 :   for (ReturnInst *Return : Returns)
     466          68 :     CallInst::Create(UnregisterFn, FuncCtx, "", Return);
     467             : 
     468             :   return true;
     469             : }
     470             : 
     471        2299 : bool SjLjEHPrepare::runOnFunction(Function &F) {
     472        2299 :   Module &M = *F.getParent();
     473        6897 :   RegisterFn = M.getOrInsertFunction(
     474             :       "_Unwind_SjLj_Register", Type::getVoidTy(M.getContext()),
     475             :       PointerType::getUnqual(FunctionContextTy));
     476        6897 :   UnregisterFn = M.getOrInsertFunction(
     477             :       "_Unwind_SjLj_Unregister", Type::getVoidTy(M.getContext()),
     478             :       PointerType::getUnqual(FunctionContextTy));
     479        2299 :   FrameAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::frameaddress);
     480        2299 :   StackAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::stacksave);
     481        2299 :   StackRestoreFn = Intrinsic::getDeclaration(&M, Intrinsic::stackrestore);
     482        2299 :   BuiltinSetupDispatchFn =
     483        4598 :     Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_setup_dispatch);
     484        2299 :   LSDAAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_lsda);
     485        2299 :   CallSiteFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_callsite);
     486        2299 :   FuncCtxFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_functioncontext);
     487             : 
     488        2299 :   bool Res = setupEntryBlockAndCallSites(F);
     489        2299 :   return Res;
     490             : }

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