| //===- SjLjEHPass.cpp - Eliminate Invoke & Unwind instructions -----------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This transformation is designed for use by code generators which use SjLj |
| // based exception handling. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #define DEBUG_TYPE "sjljehprepare" |
| #include "llvm/Transforms/Scalar.h" |
| #include "llvm/Constants.h" |
| #include "llvm/DerivedTypes.h" |
| #include "llvm/Instructions.h" |
| #include "llvm/Intrinsics.h" |
| #include "llvm/LLVMContext.h" |
| #include "llvm/Module.h" |
| #include "llvm/Pass.h" |
| #include "llvm/CodeGen/Passes.h" |
| #include "llvm/Transforms/Utils/BasicBlockUtils.h" |
| #include "llvm/Transforms/Utils/Local.h" |
| #include "llvm/ADT/Statistic.h" |
| #include "llvm/ADT/SmallVector.h" |
| #include "llvm/Support/CommandLine.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/Support/raw_ostream.h" |
| #include "llvm/Target/TargetLowering.h" |
| using namespace llvm; |
| |
| STATISTIC(NumInvokes, "Number of invokes replaced"); |
| STATISTIC(NumUnwinds, "Number of unwinds replaced"); |
| STATISTIC(NumSpilled, "Number of registers live across unwind edges"); |
| |
| namespace { |
| class SjLjEHPass : public FunctionPass { |
| |
| const TargetLowering *TLI; |
| |
| const Type *FunctionContextTy; |
| Constant *RegisterFn; |
| Constant *UnregisterFn; |
| Constant *BuiltinSetjmpFn; |
| Constant *FrameAddrFn; |
| Constant *StackAddrFn; |
| Constant *StackRestoreFn; |
| Constant *LSDAAddrFn; |
| Value *PersonalityFn; |
| Constant *SelectorFn; |
| Constant *ExceptionFn; |
| Constant *CallSiteFn; |
| |
| Value *CallSite; |
| public: |
| static char ID; // Pass identification, replacement for typeid |
| explicit SjLjEHPass(const TargetLowering *tli = NULL) |
| : FunctionPass(ID), TLI(tli) { } |
| bool doInitialization(Module &M); |
| bool runOnFunction(Function &F); |
| |
| virtual void getAnalysisUsage(AnalysisUsage &AU) const { } |
| const char *getPassName() const { |
| return "SJLJ Exception Handling preparation"; |
| } |
| |
| private: |
| void insertCallSiteStore(Instruction *I, int Number, Value *CallSite); |
| void markInvokeCallSite(InvokeInst *II, int InvokeNo, Value *CallSite, |
| SwitchInst *CatchSwitch); |
| void splitLiveRangesAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes); |
| bool insertSjLjEHSupport(Function &F); |
| }; |
| } // end anonymous namespace |
| |
| char SjLjEHPass::ID = 0; |
| |
| // Public Interface To the SjLjEHPass pass. |
| FunctionPass *llvm::createSjLjEHPass(const TargetLowering *TLI) { |
| return new SjLjEHPass(TLI); |
| } |
| // doInitialization - Set up decalarations and types needed to process |
| // exceptions. |
| bool SjLjEHPass::doInitialization(Module &M) { |
| // Build the function context structure. |
| // builtin_setjmp uses a five word jbuf |
| const Type *VoidPtrTy = |
| Type::getInt8PtrTy(M.getContext()); |
| const Type *Int32Ty = Type::getInt32Ty(M.getContext()); |
| FunctionContextTy = |
| StructType::get(M.getContext(), |
| VoidPtrTy, // __prev |
| Int32Ty, // call_site |
| ArrayType::get(Int32Ty, 4), // __data |
| VoidPtrTy, // __personality |
| VoidPtrTy, // __lsda |
| ArrayType::get(VoidPtrTy, 5), // __jbuf |
| NULL); |
| RegisterFn = M.getOrInsertFunction("_Unwind_SjLj_Register", |
| Type::getVoidTy(M.getContext()), |
| PointerType::getUnqual(FunctionContextTy), |
| (Type *)0); |
| UnregisterFn = |
| M.getOrInsertFunction("_Unwind_SjLj_Unregister", |
| Type::getVoidTy(M.getContext()), |
| PointerType::getUnqual(FunctionContextTy), |
| (Type *)0); |
| FrameAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::frameaddress); |
| StackAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::stacksave); |
| StackRestoreFn = Intrinsic::getDeclaration(&M, Intrinsic::stackrestore); |
| BuiltinSetjmpFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_setjmp); |
| LSDAAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_lsda); |
| SelectorFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_selector); |
| ExceptionFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_exception); |
| CallSiteFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_callsite); |
| PersonalityFn = 0; |
| |
| return true; |
| } |
| |
| /// insertCallSiteStore - Insert a store of the call-site value to the |
| /// function context |
| void SjLjEHPass::insertCallSiteStore(Instruction *I, int Number, |
| Value *CallSite) { |
| ConstantInt *CallSiteNoC = ConstantInt::get(Type::getInt32Ty(I->getContext()), |
| Number); |
| // Insert a store of the call-site number |
| new StoreInst(CallSiteNoC, CallSite, true, I); // volatile |
| } |
| |
| /// markInvokeCallSite - Insert code to mark the call_site for this invoke |
| void SjLjEHPass::markInvokeCallSite(InvokeInst *II, int InvokeNo, |
| Value *CallSite, |
| SwitchInst *CatchSwitch) { |
| ConstantInt *CallSiteNoC= ConstantInt::get(Type::getInt32Ty(II->getContext()), |
| InvokeNo); |
| // The runtime comes back to the dispatcher with the call_site - 1 in |
| // the context. Odd, but there it is. |
| ConstantInt *SwitchValC = ConstantInt::get(Type::getInt32Ty(II->getContext()), |
| InvokeNo - 1); |
| |
| // If the unwind edge has phi nodes, split the edge. |
| if (isa<PHINode>(II->getUnwindDest()->begin())) { |
| SplitCriticalEdge(II, 1, this); |
| |
| // If there are any phi nodes left, they must have a single predecessor. |
| while (PHINode *PN = dyn_cast<PHINode>(II->getUnwindDest()->begin())) { |
| PN->replaceAllUsesWith(PN->getIncomingValue(0)); |
| PN->eraseFromParent(); |
| } |
| } |
| |
| // Insert the store of the call site value |
| insertCallSiteStore(II, InvokeNo, CallSite); |
| |
| // Record the call site value for the back end so it stays associated with |
| // the invoke. |
| CallInst::Create(CallSiteFn, CallSiteNoC, "", II); |
| |
| // Add a switch case to our unwind block. |
| CatchSwitch->addCase(SwitchValC, II->getUnwindDest()); |
| // We still want this to look like an invoke so we emit the LSDA properly, |
| // so we don't transform the invoke into a call here. |
| } |
| |
| /// MarkBlocksLiveIn - Insert BB and all of its predescessors into LiveBBs until |
| /// we reach blocks we've already seen. |
| static void MarkBlocksLiveIn(BasicBlock *BB, std::set<BasicBlock*> &LiveBBs) { |
| if (!LiveBBs.insert(BB).second) return; // already been here. |
| |
| for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) |
| MarkBlocksLiveIn(*PI, LiveBBs); |
| } |
| |
| /// splitLiveRangesAcrossInvokes - Each value that is live across an unwind edge |
| /// we spill into a stack location, guaranteeing that there is nothing live |
| /// across the unwind edge. This process also splits all critical edges |
| /// coming out of invoke's. |
| /// FIXME: Move this function to a common utility file (Local.cpp?) so |
| /// both SjLj and LowerInvoke can use it. |
| void SjLjEHPass:: |
| splitLiveRangesAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes) { |
| // First step, split all critical edges from invoke instructions. |
| for (unsigned i = 0, e = Invokes.size(); i != e; ++i) { |
| InvokeInst *II = Invokes[i]; |
| SplitCriticalEdge(II, 0, this); |
| SplitCriticalEdge(II, 1, this); |
| assert(!isa<PHINode>(II->getNormalDest()) && |
| !isa<PHINode>(II->getUnwindDest()) && |
| "critical edge splitting left single entry phi nodes?"); |
| } |
| |
| Function *F = Invokes.back()->getParent()->getParent(); |
| |
| // To avoid having to handle incoming arguments specially, we lower each arg |
| // to a copy instruction in the entry block. This ensures that the argument |
| // value itself cannot be live across the entry block. |
| BasicBlock::iterator AfterAllocaInsertPt = F->begin()->begin(); |
| while (isa<AllocaInst>(AfterAllocaInsertPt) && |
| isa<ConstantInt>(cast<AllocaInst>(AfterAllocaInsertPt)->getArraySize())) |
| ++AfterAllocaInsertPt; |
| for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end(); |
| AI != E; ++AI) { |
| const Type *Ty = AI->getType(); |
| // Aggregate types can't be cast, but are legal argument types, so we have |
| // to handle them differently. We use an extract/insert pair as a |
| // lightweight method to achieve the same goal. |
| if (isa<StructType>(Ty) || isa<ArrayType>(Ty) || isa<VectorType>(Ty)) { |
| Instruction *EI = ExtractValueInst::Create(AI, 0, "",AfterAllocaInsertPt); |
| Instruction *NI = InsertValueInst::Create(AI, EI, 0); |
| NI->insertAfter(EI); |
| AI->replaceAllUsesWith(NI); |
| // Set the operand of the instructions back to the AllocaInst. |
| EI->setOperand(0, AI); |
| NI->setOperand(0, AI); |
| } else { |
| // This is always a no-op cast because we're casting AI to AI->getType() |
| // so src and destination types are identical. BitCast is the only |
| // possibility. |
| CastInst *NC = new BitCastInst( |
| AI, AI->getType(), AI->getName()+".tmp", AfterAllocaInsertPt); |
| AI->replaceAllUsesWith(NC); |
| // Set the operand of the cast instruction back to the AllocaInst. |
| // Normally it's forbidden to replace a CastInst's operand because it |
| // could cause the opcode to reflect an illegal conversion. However, |
| // we're replacing it here with the same value it was constructed with. |
| // We do this because the above replaceAllUsesWith() clobbered the |
| // operand, but we want this one to remain. |
| NC->setOperand(0, AI); |
| } |
| } |
| |
| // Finally, scan the code looking for instructions with bad live ranges. |
| for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) |
| for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ++II) { |
| // Ignore obvious cases we don't have to handle. In particular, most |
| // instructions either have no uses or only have a single use inside the |
| // current block. Ignore them quickly. |
| Instruction *Inst = II; |
| if (Inst->use_empty()) continue; |
| if (Inst->hasOneUse() && |
| cast<Instruction>(Inst->use_back())->getParent() == BB && |
| !isa<PHINode>(Inst->use_back())) continue; |
| |
| // If this is an alloca in the entry block, it's not a real register |
| // value. |
| if (AllocaInst *AI = dyn_cast<AllocaInst>(Inst)) |
| if (isa<ConstantInt>(AI->getArraySize()) && BB == F->begin()) |
| continue; |
| |
| // Avoid iterator invalidation by copying users to a temporary vector. |
| SmallVector<Instruction*,16> Users; |
| for (Value::use_iterator UI = Inst->use_begin(), E = Inst->use_end(); |
| UI != E; ++UI) { |
| Instruction *User = cast<Instruction>(*UI); |
| if (User->getParent() != BB || isa<PHINode>(User)) |
| Users.push_back(User); |
| } |
| |
| // Find all of the blocks that this value is live in. |
| std::set<BasicBlock*> LiveBBs; |
| LiveBBs.insert(Inst->getParent()); |
| while (!Users.empty()) { |
| Instruction *U = Users.back(); |
| Users.pop_back(); |
| |
| if (!isa<PHINode>(U)) { |
| MarkBlocksLiveIn(U->getParent(), LiveBBs); |
| } else { |
| // Uses for a PHI node occur in their predecessor block. |
| PHINode *PN = cast<PHINode>(U); |
| for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) |
| if (PN->getIncomingValue(i) == Inst) |
| MarkBlocksLiveIn(PN->getIncomingBlock(i), LiveBBs); |
| } |
| } |
| |
| // Now that we know all of the blocks that this thing is live in, see if |
| // it includes any of the unwind locations. |
| bool NeedsSpill = false; |
| for (unsigned i = 0, e = Invokes.size(); i != e; ++i) { |
| BasicBlock *UnwindBlock = Invokes[i]->getUnwindDest(); |
| if (UnwindBlock != BB && LiveBBs.count(UnwindBlock)) { |
| NeedsSpill = true; |
| } |
| } |
| |
| // If we decided we need a spill, do it. |
| // FIXME: Spilling this way is overkill, as it forces all uses of |
| // the value to be reloaded from the stack slot, even those that aren't |
| // in the unwind blocks. We should be more selective. |
| if (NeedsSpill) { |
| ++NumSpilled; |
| DemoteRegToStack(*Inst, true); |
| } |
| } |
| } |
| |
| bool SjLjEHPass::insertSjLjEHSupport(Function &F) { |
| SmallVector<ReturnInst*,16> Returns; |
| SmallVector<UnwindInst*,16> Unwinds; |
| SmallVector<InvokeInst*,16> Invokes; |
| |
| // Look through the terminators of the basic blocks to find invokes, returns |
| // and unwinds. |
| for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) { |
| if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) { |
| // Remember all return instructions in case we insert an invoke into this |
| // function. |
| Returns.push_back(RI); |
| } else if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) { |
| Invokes.push_back(II); |
| } else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) { |
| Unwinds.push_back(UI); |
| } |
| } |
| // If we don't have any invokes or unwinds, there's nothing to do. |
| if (Unwinds.empty() && Invokes.empty()) return false; |
| |
| // Find the eh.selector.*, eh.exception and alloca calls. |
| // |
| // Remember any allocas() that aren't in the entry block, as the |
| // jmpbuf saved SP will need to be updated for them. |
| // |
| // We'll use the first eh.selector to determine the right personality |
| // function to use. For SJLJ, we always use the same personality for the |
| // whole function, not on a per-selector basis. |
| // FIXME: That's a bit ugly. Better way? |
| SmallVector<CallInst*,16> EH_Selectors; |
| SmallVector<CallInst*,16> EH_Exceptions; |
| SmallVector<Instruction*,16> JmpbufUpdatePoints; |
| // Note: Skip the entry block since there's nothing there that interests |
| // us. eh.selector and eh.exception shouldn't ever be there, and we |
| // want to disregard any allocas that are there. |
| for (Function::iterator BB = F.begin(), E = F.end(); ++BB != E;) { |
| for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) { |
| if (CallInst *CI = dyn_cast<CallInst>(I)) { |
| if (CI->getCalledFunction() == SelectorFn) { |
| if (!PersonalityFn) PersonalityFn = CI->getArgOperand(1); |
| EH_Selectors.push_back(CI); |
| } else if (CI->getCalledFunction() == ExceptionFn) { |
| EH_Exceptions.push_back(CI); |
| } else if (CI->getCalledFunction() == StackRestoreFn) { |
| JmpbufUpdatePoints.push_back(CI); |
| } |
| } else if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) { |
| JmpbufUpdatePoints.push_back(AI); |
| } |
| } |
| } |
| // If we don't have any eh.selector calls, we can't determine the personality |
| // function. Without a personality function, we can't process exceptions. |
| if (!PersonalityFn) return false; |
| |
| NumInvokes += Invokes.size(); |
| NumUnwinds += Unwinds.size(); |
| |
| if (!Invokes.empty()) { |
| // We have invokes, so we need to add register/unregister calls to get |
| // this function onto the global unwind stack. |
| // |
| // First thing we need to do is scan the whole function for values that are |
| // live across unwind edges. Each value that is live across an unwind edge |
| // we spill into a stack location, guaranteeing that there is nothing live |
| // across the unwind edge. This process also splits all critical edges |
| // coming out of invoke's. |
| splitLiveRangesAcrossInvokes(Invokes); |
| |
| BasicBlock *EntryBB = F.begin(); |
| // Create an alloca for the incoming jump buffer ptr and the new jump buffer |
| // that needs to be restored on all exits from the function. This is an |
| // alloca because the value needs to be added to the global context list. |
| unsigned Align = 4; // FIXME: Should be a TLI check? |
| AllocaInst *FunctionContext = |
| new AllocaInst(FunctionContextTy, 0, Align, |
| "fcn_context", F.begin()->begin()); |
| |
| Value *Idxs[2]; |
| const Type *Int32Ty = Type::getInt32Ty(F.getContext()); |
| Value *Zero = ConstantInt::get(Int32Ty, 0); |
| // We need to also keep around a reference to the call_site field |
| Idxs[0] = Zero; |
| Idxs[1] = ConstantInt::get(Int32Ty, 1); |
| CallSite = GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, |
| "call_site", |
| EntryBB->getTerminator()); |
| |
| // The exception selector comes back in context->data[1] |
| Idxs[1] = ConstantInt::get(Int32Ty, 2); |
| Value *FCData = GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, |
| "fc_data", |
| EntryBB->getTerminator()); |
| Idxs[1] = ConstantInt::get(Int32Ty, 1); |
| Value *SelectorAddr = GetElementPtrInst::Create(FCData, Idxs, Idxs+2, |
| "exc_selector_gep", |
| EntryBB->getTerminator()); |
| // The exception value comes back in context->data[0] |
| Idxs[1] = Zero; |
| Value *ExceptionAddr = GetElementPtrInst::Create(FCData, Idxs, Idxs+2, |
| "exception_gep", |
| EntryBB->getTerminator()); |
| |
| // The result of the eh.selector call will be replaced with a |
| // a reference to the selector value returned in the function |
| // context. We leave the selector itself so the EH analysis later |
| // can use it. |
| for (int i = 0, e = EH_Selectors.size(); i < e; ++i) { |
| CallInst *I = EH_Selectors[i]; |
| Value *SelectorVal = new LoadInst(SelectorAddr, "select_val", true, I); |
| I->replaceAllUsesWith(SelectorVal); |
| } |
| // eh.exception calls are replaced with references to the proper |
| // location in the context. Unlike eh.selector, the eh.exception |
| // calls are removed entirely. |
| for (int i = 0, e = EH_Exceptions.size(); i < e; ++i) { |
| CallInst *I = EH_Exceptions[i]; |
| // Possible for there to be duplicates, so check to make sure |
| // the instruction hasn't already been removed. |
| if (!I->getParent()) continue; |
| Value *Val = new LoadInst(ExceptionAddr, "exception", true, I); |
| const Type *Ty = Type::getInt8PtrTy(F.getContext()); |
| Val = CastInst::Create(Instruction::IntToPtr, Val, Ty, "", I); |
| |
| I->replaceAllUsesWith(Val); |
| I->eraseFromParent(); |
| } |
| |
| // The entry block changes to have the eh.sjlj.setjmp, with a conditional |
| // branch to a dispatch block for non-zero returns. If we return normally, |
| // we're not handling an exception and just register the function context |
| // and continue. |
| |
| // Create the dispatch block. The dispatch block is basically a big switch |
| // statement that goes to all of the invoke landing pads. |
| BasicBlock *DispatchBlock = |
| BasicBlock::Create(F.getContext(), "eh.sjlj.setjmp.catch", &F); |
| |
| // Insert a load in the Catch block, and a switch on its value. By default, |
| // we go to a block that just does an unwind (which is the correct action |
| // for a standard call). |
| BasicBlock *UnwindBlock = |
| BasicBlock::Create(F.getContext(), "unwindbb", &F); |
| Unwinds.push_back(new UnwindInst(F.getContext(), UnwindBlock)); |
| |
| Value *DispatchLoad = new LoadInst(CallSite, "invoke.num", true, |
| DispatchBlock); |
| SwitchInst *DispatchSwitch = |
| SwitchInst::Create(DispatchLoad, UnwindBlock, Invokes.size(), |
| DispatchBlock); |
| // Split the entry block to insert the conditional branch for the setjmp. |
| BasicBlock *ContBlock = EntryBB->splitBasicBlock(EntryBB->getTerminator(), |
| "eh.sjlj.setjmp.cont"); |
| |
| // Populate the Function Context |
| // 1. LSDA address |
| // 2. Personality function address |
| // 3. jmpbuf (save SP, FP and call eh.sjlj.setjmp) |
| |
| // LSDA address |
| Idxs[0] = Zero; |
| Idxs[1] = ConstantInt::get(Int32Ty, 4); |
| Value *LSDAFieldPtr = |
| GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, |
| "lsda_gep", |
| EntryBB->getTerminator()); |
| Value *LSDA = CallInst::Create(LSDAAddrFn, "lsda_addr", |
| EntryBB->getTerminator()); |
| new StoreInst(LSDA, LSDAFieldPtr, true, EntryBB->getTerminator()); |
| |
| Idxs[1] = ConstantInt::get(Int32Ty, 3); |
| Value *PersonalityFieldPtr = |
| GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, |
| "lsda_gep", |
| EntryBB->getTerminator()); |
| new StoreInst(PersonalityFn, PersonalityFieldPtr, true, |
| EntryBB->getTerminator()); |
| |
| // Save the frame pointer. |
| Idxs[1] = ConstantInt::get(Int32Ty, 5); |
| Value *JBufPtr |
| = GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, |
| "jbuf_gep", |
| EntryBB->getTerminator()); |
| Idxs[1] = ConstantInt::get(Int32Ty, 0); |
| Value *FramePtr = |
| GetElementPtrInst::Create(JBufPtr, Idxs, Idxs+2, "jbuf_fp_gep", |
| EntryBB->getTerminator()); |
| |
| Value *Val = CallInst::Create(FrameAddrFn, |
| ConstantInt::get(Int32Ty, 0), |
| "fp", |
| EntryBB->getTerminator()); |
| new StoreInst(Val, FramePtr, true, EntryBB->getTerminator()); |
| |
| // Save the stack pointer. |
| Idxs[1] = ConstantInt::get(Int32Ty, 2); |
| Value *StackPtr = |
| GetElementPtrInst::Create(JBufPtr, Idxs, Idxs+2, "jbuf_sp_gep", |
| EntryBB->getTerminator()); |
| |
| Val = CallInst::Create(StackAddrFn, "sp", EntryBB->getTerminator()); |
| new StoreInst(Val, StackPtr, true, EntryBB->getTerminator()); |
| |
| // Call the setjmp instrinsic. It fills in the rest of the jmpbuf. |
| Value *SetjmpArg = |
| CastInst::Create(Instruction::BitCast, JBufPtr, |
| Type::getInt8PtrTy(F.getContext()), "", |
| EntryBB->getTerminator()); |
| Value *DispatchVal = CallInst::Create(BuiltinSetjmpFn, SetjmpArg, |
| "dispatch", |
| EntryBB->getTerminator()); |
| // check the return value of the setjmp. non-zero goes to dispatcher. |
| Value *IsNormal = new ICmpInst(EntryBB->getTerminator(), |
| ICmpInst::ICMP_EQ, DispatchVal, Zero, |
| "notunwind"); |
| // Nuke the uncond branch. |
| EntryBB->getTerminator()->eraseFromParent(); |
| |
| // Put in a new condbranch in its place. |
| BranchInst::Create(ContBlock, DispatchBlock, IsNormal, EntryBB); |
| |
| // Register the function context and make sure it's known to not throw |
| CallInst *Register = |
| CallInst::Create(RegisterFn, FunctionContext, "", |
| ContBlock->getTerminator()); |
| Register->setDoesNotThrow(); |
| |
| // At this point, we are all set up, update the invoke instructions |
| // to mark their call_site values, and fill in the dispatch switch |
| // accordingly. |
| for (unsigned i = 0, e = Invokes.size(); i != e; ++i) |
| markInvokeCallSite(Invokes[i], i+1, CallSite, DispatchSwitch); |
| |
| // Mark call instructions that aren't nounwind as no-action |
| // (call_site == -1). Skip the entry block, as prior to then, no function |
| // context has been created for this function and any unexpected exceptions |
| // thrown will go directly to the caller's context, which is what we want |
| // anyway, so no need to do anything here. |
| for (Function::iterator BB = F.begin(), E = F.end(); ++BB != E;) { |
| for (BasicBlock::iterator I = BB->begin(), end = BB->end(); I != end; ++I) |
| if (CallInst *CI = dyn_cast<CallInst>(I)) { |
| // Ignore calls to the EH builtins (eh.selector, eh.exception) |
| Constant *Callee = CI->getCalledFunction(); |
| if (Callee != SelectorFn && Callee != ExceptionFn |
| && !CI->doesNotThrow()) |
| insertCallSiteStore(CI, -1, CallSite); |
| } |
| } |
| |
| // Replace all unwinds with a branch to the unwind handler. |
| // ??? Should this ever happen with sjlj exceptions? |
| for (unsigned i = 0, e = Unwinds.size(); i != e; ++i) { |
| BranchInst::Create(UnwindBlock, Unwinds[i]); |
| Unwinds[i]->eraseFromParent(); |
| } |
| |
| // Following any allocas not in the entry block, update the saved SP |
| // in the jmpbuf to the new value. |
| for (unsigned i = 0, e = JmpbufUpdatePoints.size(); i != e; ++i) { |
| Instruction *AI = JmpbufUpdatePoints[i]; |
| Instruction *StackAddr = CallInst::Create(StackAddrFn, "sp"); |
| StackAddr->insertAfter(AI); |
| Instruction *StoreStackAddr = new StoreInst(StackAddr, StackPtr, true); |
| StoreStackAddr->insertAfter(StackAddr); |
| } |
| |
| // Finally, for any returns from this function, if this function contains an |
| // invoke, add a call to unregister the function context. |
| for (unsigned i = 0, e = Returns.size(); i != e; ++i) |
| CallInst::Create(UnregisterFn, FunctionContext, "", Returns[i]); |
| } |
| |
| return true; |
| } |
| |
| bool SjLjEHPass::runOnFunction(Function &F) { |
| bool Res = insertSjLjEHSupport(F); |
| return Res; |
| } |