diff --git a/include/llvm/CodeGen/Passes.h b/include/llvm/CodeGen/Passes.h index 7365c447962..d8ec67f9163 100644 --- a/include/llvm/CodeGen/Passes.h +++ b/include/llvm/CodeGen/Passes.h @@ -193,6 +193,10 @@ namespace llvm { /// adapted to code generation. Required if using dwarf exception handling. FunctionPass *createDwarfEHPass(const TargetLowering *tli, bool fast); + /// createSjLjEHPass - This pass adapts exception handling code to use + /// the GCC-style builtin setjmp/longjmp (sjlj) to handling EH control flow. + FunctionPass *createSjLjEHPass(const TargetLowering *tli); + } // End llvm namespace #endif diff --git a/lib/CodeGen/AsmPrinter/DwarfException.cpp b/lib/CodeGen/AsmPrinter/DwarfException.cpp index 77e4ddd1010..dacaf1b8fdb 100644 --- a/lib/CodeGen/AsmPrinter/DwarfException.cpp +++ b/lib/CodeGen/AsmPrinter/DwarfException.cpp @@ -364,7 +364,6 @@ ComputeActionsTable(const SmallVectorImpl &LandingPads, /// try-range address. void DwarfException:: ComputeCallSiteTable(SmallVectorImpl &CallSites, - std::map &CallSiteIndexMap, const RangeMapType &PadMap, const SmallVectorImpl &LandingPads, const SmallVectorImpl &FirstActions) { @@ -438,12 +437,6 @@ ComputeCallSiteTable(SmallVectorImpl &CallSites, // Otherwise, create a new call-site. CallSites.push_back(Site); - // For SjLj handling, map the call site entry to its index - if (TAI->getExceptionHandlingType() == ExceptionHandling::SjLj) { - unsigned Index = - MF->getLandingPadCallSiteIndex(LandingPad->LandingPadBlock); - CallSiteIndexMap[Index] = &CallSites.back(); - } PreviousIsInvoke = true; } else { // Create a gap. @@ -520,9 +513,7 @@ void DwarfException::EmitExceptionTable() { // Compute the call-site table. SmallVector CallSites; - std::map CallSiteIndexMap; - ComputeCallSiteTable(CallSites, CallSiteIndexMap, PadMap, - LandingPads, FirstActions); + ComputeCallSiteTable(CallSites, PadMap, LandingPads, FirstActions); // Final tallies. @@ -537,8 +528,7 @@ void DwarfException::EmitExceptionTable() { if (TAI->getExceptionHandlingType() == ExceptionHandling::SjLj) { - SizeSites = (MF->getMaxCallSiteIndex() - CallSites.size()) * - TargetAsmInfo::getULEB128Size(0) * 2; + SizeSites = 0; } else SizeSites = CallSites.size() * (SiteStartSize + SiteLengthSize + LandingPadSize); @@ -546,7 +536,6 @@ void DwarfException::EmitExceptionTable() { SizeSites += TargetAsmInfo::getULEB128Size(CallSites[i].Action); if (TAI->getExceptionHandlingType() == ExceptionHandling::SjLj) SizeSites += TargetAsmInfo::getULEB128Size(i); - // FIXME: 'i' above should be the landing pad index } // Type infos. const unsigned TypeInfoSize = TD->getPointerSize(); // DW_EH_PE_absptr @@ -655,25 +644,11 @@ void DwarfException::EmitExceptionTable() { assert(MF->getCallSiteCount() == CallSites.size()); // Emit the landing pad site information. - // SjLj handling assigned the call site indices in the front end, so - // we need to make sure the table here lines up with that. That's pretty - // horrible, and should be fixed ASAP to do that stuff in the back end - // instead. - std::map::const_iterator I, E; - I = CallSiteIndexMap.begin(); - E = CallSiteIndexMap.end(); - for (unsigned CurrIdx = 1; I != E; ++I) { - // paranoia. - assert(CurrIdx <= I->first); - // Fill in any gaps in the table - while (CurrIdx++ < I->first) { - Asm->EmitULEB128Bytes(0); - Asm->EOL("Filler landing pad"); - Asm->EmitULEB128Bytes(0); - Asm->EOL("Filler action"); - } - const CallSiteEntry &S = *(I->second); - Asm->EmitULEB128Bytes(I->first - 1); + unsigned idx = 0; + for (SmallVectorImpl::const_iterator + I = CallSites.begin(), E = CallSites.end(); I != E; ++I, ++idx) { + const CallSiteEntry &S = *I; + Asm->EmitULEB128Bytes(idx); Asm->EOL("Landing pad"); Asm->EmitULEB128Bytes(S.Action); Asm->EOL("Action"); diff --git a/lib/CodeGen/AsmPrinter/DwarfException.h b/lib/CodeGen/AsmPrinter/DwarfException.h index ee390cff013..e165df4693d 100644 --- a/lib/CodeGen/AsmPrinter/DwarfException.h +++ b/lib/CodeGen/AsmPrinter/DwarfException.h @@ -155,7 +155,6 @@ class VISIBILITY_HIDDEN DwarfException : public Dwarf { /// of any entry - they form gaps in the table. Entries must be ordered by /// try-range address. void ComputeCallSiteTable(SmallVectorImpl &CallSites, - std::map &CallSiteIndexMap, const RangeMapType &PadMap, const SmallVectorImpl &LPs, const SmallVectorImpl &FirstActions); diff --git a/lib/CodeGen/LLVMTargetMachine.cpp b/lib/CodeGen/LLVMTargetMachine.cpp index 182f9cfc82e..911e9a13ef3 100644 --- a/lib/CodeGen/LLVMTargetMachine.cpp +++ b/lib/CodeGen/LLVMTargetMachine.cpp @@ -241,8 +241,11 @@ bool LLVMTargetMachine::addCommonCodeGenPasses(PassManagerBase &PM, // handle. switch (getTargetAsmInfo()->getExceptionHandlingType()) { - // SjLj piggy-backs on dwarf for this bit case ExceptionHandling::SjLj: + // SjLj piggy-backs on dwarf for this bit. The cleanups done apply to both + PM.add(createDwarfEHPass(getTargetLowering(), OptLevel==CodeGenOpt::None)); + PM.add(createSjLjEHPass(getTargetLowering())); + break; case ExceptionHandling::Dwarf: PM.add(createDwarfEHPass(getTargetLowering(), OptLevel==CodeGenOpt::None)); break; diff --git a/lib/CodeGen/SjLjEHPrepare.cpp b/lib/CodeGen/SjLjEHPrepare.cpp new file mode 100644 index 00000000000..6a8213faae4 --- /dev/null +++ b/lib/CodeGen/SjLjEHPrepare.cpp @@ -0,0 +1,527 @@ +//===- 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/Support/CommandLine.h" +#include "llvm/Support/Compiler.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/raw_ostream.h" +#include "llvm/Target/TargetLowering.h" +#include +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 VISIBILITY_HIDDEN SjLjEHPass : public FunctionPass { + + const TargetLowering *TLI; + + const Type *FunctionContextTy; + Constant *RegisterFn; + Constant *UnregisterFn; + Constant *ResumeFn; + Constant *BuiltinSetjmpFn; + Constant *FrameAddrFn; + Constant *LSDAAddrFn; + Value *PersonalityFn; + Constant *Selector32Fn; + Constant *Selector64Fn; + Constant *ExceptionFn; + + 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 markInvokeCallSite(InvokeInst *II, unsigned InvokeNo, + Value *CallSite, + SwitchInst *CatchSwitch); + void splitLiveRangesLiveAcrossInvokes(std::vector &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 - Make sure that there is a prototype for abort in the +// current module. +bool SjLjEHPass::doInitialization(Module &M) { + // Build the function context structure. + // builtin_setjmp uses a five word jbuf + const Type *VoidPtrTy = + PointerType::getUnqual(Type::getInt8Ty(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); + ResumeFn = + M.getOrInsertFunction("_Unwind_SjLj_Resume", + Type::getVoidTy(M.getContext()), + VoidPtrTy, + (Type *)0); + FrameAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::frameaddress); + BuiltinSetjmpFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_setjmp); + LSDAAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_lsda); + Selector32Fn = Intrinsic::getDeclaration(&M, Intrinsic::eh_selector_i32); + Selector64Fn = Intrinsic::getDeclaration(&M, Intrinsic::eh_selector_i64); + ExceptionFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_exception); + + return true; +} + +/// markInvokeCallSite - Insert code to mark the call_site for this invoke +void SjLjEHPass::markInvokeCallSite(InvokeInst *II, unsigned 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(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(II->getUnwindDest()->begin())) { + PN->replaceAllUsesWith(PN->getIncomingValue(0)); + PN->eraseFromParent(); + } + } + + // Insert a store of the invoke num before the invoke and store zero into the + // location afterward. + new StoreInst(CallSiteNoC, CallSite, true, II); // volatile + + // 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 + // FIXME: ??? Or will this cause strangeness with mis-matched IDs like + // when it was in the front end? +} + +/// 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 &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); +} + +// 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. +void SjLjEHPass:: +splitLiveRangesLiveAcrossInvokes(std::vector &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(II->getNormalDest()) && + !isa(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(AfterAllocaInsertPt) && + isa(cast(AfterAllocaInsertPt)->getArraySize())) + ++AfterAllocaInsertPt; + for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end(); + AI != E; ++AI) { + // 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); + // Normally its is 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 to simply + // make NC its user. + 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(Inst->use_back())->getParent() == BB && + !isa(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(Inst)) + if (isa(AI->getArraySize()) && BB == F->begin()) + continue; + + // Avoid iterator invalidation by copying users to a temporary vector. + std::vector Users; + for (Value::use_iterator UI = Inst->use_begin(), E = Inst->use_end(); + UI != E; ++UI) { + Instruction *User = cast(*UI); + if (User->getParent() != BB || isa(User)) + Users.push_back(User); + } + + // Scan all of the uses and see if the live range is live across an unwind + // edge. If we find a use live across an invoke edge, create an alloca + // and spill the value. + std::set InvokesWithStoreInserted; + + // Find all of the blocks that this value is live in. + std::set LiveBBs; + LiveBBs.insert(Inst->getParent()); + while (!Users.empty()) { + Instruction *U = Users.back(); + Users.pop_back(); + + if (!isa(U)) { + MarkBlocksLiveIn(U->getParent(), LiveBBs); + } else { + // Uses for a PHI node occur in their predecessor block. + PHINode *PN = cast(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. + if (NeedsSpill) { + ++NumSpilled; + DemoteRegToStack(*Inst, true); + } + } +} + +bool SjLjEHPass::insertSjLjEHSupport(Function &F) { + std::vector Returns; + std::vector Unwinds; + std::vector 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(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(BB->getTerminator())) { + Invokes.push_back(II); + } else if (UnwindInst *UI = dyn_cast(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; + + 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. + splitLiveRangesLiveAcrossInvokes(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()); + + // Find the eh.selector.* and eh.exception calls. We'll use the first + // ex.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? + std::vector EH_Selectors; + std::vector EH_Exceptions; + for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) { + // for (unsigned i = 0, e = Invokes.size(); i != e; ++i) { +// BasicBlock *Pad = Invokes[0]->getUnwindDest(); + for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) { + if (CallInst *CI = dyn_cast(I)) { + if (CI->getCalledFunction() == Selector32Fn || + CI->getCalledFunction() == Selector64Fn) { + if (!PersonalityFn) PersonalityFn = CI->getOperand(2); + EH_Selectors.push_back(CI); + } else if (CI->getCalledFunction() == ExceptionFn) { + EH_Exceptions.push_back(CI); + } + } + } + } + // 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); + Val = CastInst::Create(Instruction::IntToPtr, Val, + PointerType::getUnqual(Type::getInt8Ty(F.getContext())), + "", 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 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 *FieldPtr + = GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, + "jbuf_gep", + EntryBB->getTerminator()); + Idxs[1] = ConstantInt::get(Int32Ty, 0); + Value *ElemPtr = + GetElementPtrInst::Create(FieldPtr, Idxs, Idxs+2, "jbuf_fp_gep", + EntryBB->getTerminator()); + + Value *Val = CallInst::Create(FrameAddrFn, + ConstantInt::get(Int32Ty, 0), + "fp", + EntryBB->getTerminator()); + new StoreInst(Val, ElemPtr, true, EntryBB->getTerminator()); + // Call the setjmp instrinsic. It fills in the rest of the jmpbuf + Value *SetjmpArg = + CastInst::Create(Instruction::BitCast, FieldPtr, + Type::getInt8Ty(F.getContext())->getPointerTo(), "", + 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); + + // The front end has likely added calls to _Unwind_Resume. We need + // to find those calls and mark the call_site as -1 immediately prior. + // resume is a noreturn function, so any block that has a call to it + // should end in an 'unreachable' instruction with the call immediately + // prior. That's how we'll search. + // ??? There's got to be a better way. this is fugly. + for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) + if ((dyn_cast(BB->getTerminator()))) { + BasicBlock::iterator I = BB->getTerminator(); + // Check the previous instruction and see if it's a resume call + if (I == BB->begin()) continue; + if (CallInst *CI = dyn_cast(--I)) { + if (CI->getCalledFunction() == ResumeFn) { + Value *NegativeOne = ConstantInt::get(Int32Ty, -1); + new StoreInst(NegativeOne, CallSite, true, I); // volatile + } + } + } + + // 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(); + } + + // 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; +}