| //===- LowerSetJmp.cpp - Code pertaining to lowering set/long jumps -------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file was developed by the LLVM research group and is distributed under |
| // the University of Illinois Open Source License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file implements the lowering of setjmp and longjmp to use the |
| // LLVM invoke and unwind instructions as necessary. |
| // |
| // Lowering of longjmp is fairly trivial. We replace the call with a |
| // call to the LLVM library function "__llvm_sjljeh_throw_longjmp()". |
| // This unwinds the stack for us calling all of the destructors for |
| // objects allocated on the stack. |
| // |
| // At a setjmp call, the basic block is split and the setjmp removed. |
| // The calls in a function that have a setjmp are converted to invoke |
| // where the except part checks to see if it's a longjmp exception and, |
| // if so, if it's handled in the function. If it is, then it gets the |
| // value returned by the longjmp and goes to where the basic block was |
| // split. Invoke instructions are handled in a similar fashion with the |
| // original except block being executed if it isn't a longjmp except |
| // that is handled by that function. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| //===----------------------------------------------------------------------===// |
| // FIXME: This pass doesn't deal with PHI statements just yet. That is, |
| // we expect this to occur before SSAification is done. This would seem |
| // to make sense, but in general, it might be a good idea to make this |
| // pass invokable via the "opt" command at will. |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/Constants.h" |
| #include "llvm/DerivedTypes.h" |
| #include "llvm/Instructions.h" |
| #include "llvm/Intrinsics.h" |
| #include "llvm/Module.h" |
| #include "llvm/Pass.h" |
| #include "llvm/Support/CFG.h" |
| #include "llvm/Support/InstVisitor.h" |
| #include "llvm/Transforms/Utils/DemoteRegToStack.h" |
| #include "Support/DepthFirstIterator.h" |
| #include "Support/Statistic.h" |
| #include "Support/StringExtras.h" |
| #include "Support/VectorExtras.h" |
| |
| namespace llvm { |
| |
| namespace { |
| Statistic<> LongJmpsTransformed("lowersetjmp", |
| "Number of longjmps transformed"); |
| Statistic<> SetJmpsTransformed("lowersetjmp", |
| "Number of setjmps transformed"); |
| Statistic<> CallsTransformed("lowersetjmp", |
| "Number of calls invokified"); |
| Statistic<> InvokesTransformed("lowersetjmp", |
| "Number of invokes modified"); |
| |
| //===--------------------------------------------------------------------===// |
| // LowerSetJmp pass implementation. This is subclassed from the "Pass" |
| // class because it works on a module as a whole, not a function at a |
| // time. |
| |
| class LowerSetJmp : public Pass, |
| public InstVisitor<LowerSetJmp> { |
| // LLVM library functions... |
| Function* InitSJMap; // __llvm_sjljeh_init_setjmpmap |
| Function* DestroySJMap; // __llvm_sjljeh_destroy_setjmpmap |
| Function* AddSJToMap; // __llvm_sjljeh_add_setjmp_to_map |
| Function* ThrowLongJmp; // __llvm_sjljeh_throw_longjmp |
| Function* TryCatchLJ; // __llvm_sjljeh_try_catching_longjmp_exception |
| Function* IsLJException; // __llvm_sjljeh_is_longjmp_exception |
| Function* GetLJValue; // __llvm_sjljeh_get_longjmp_value |
| |
| typedef std::pair<SwitchInst*, CallInst*> SwitchValuePair; |
| |
| // Keep track of those basic blocks reachable via a depth-first search of |
| // the CFG from a setjmp call. We only need to transform those "call" and |
| // "invoke" instructions that are reachable from the setjmp call site. |
| std::set<BasicBlock*> DFSBlocks; |
| |
| // The setjmp map is going to hold information about which setjmps |
| // were called (each setjmp gets its own number) and with which |
| // buffer it was called. |
| std::map<Function*, AllocaInst*> SJMap; |
| |
| // The rethrow basic block map holds the basic block to branch to if |
| // the exception isn't handled in the current function and needs to |
| // be rethrown. |
| std::map<const Function*, BasicBlock*> RethrowBBMap; |
| |
| // The preliminary basic block map holds a basic block that grabs the |
| // exception and determines if it's handled by the current function. |
| std::map<const Function*, BasicBlock*> PrelimBBMap; |
| |
| // The switch/value map holds a switch inst/call inst pair. The |
| // switch inst controls which handler (if any) gets called and the |
| // value is the value returned to that handler by the call to |
| // __llvm_sjljeh_get_longjmp_value. |
| std::map<const Function*, SwitchValuePair> SwitchValMap; |
| |
| // A map of which setjmps we've seen so far in a function. |
| std::map<const Function*, unsigned> SetJmpIDMap; |
| |
| AllocaInst* GetSetJmpMap(Function* Func); |
| BasicBlock* GetRethrowBB(Function* Func); |
| SwitchValuePair GetSJSwitch(Function* Func, BasicBlock* Rethrow); |
| |
| void TransformLongJmpCall(CallInst* Inst); |
| void TransformSetJmpCall(CallInst* Inst); |
| |
| bool IsTransformableFunction(const std::string& Name); |
| public: |
| void visitCallInst(CallInst& CI); |
| void visitInvokeInst(InvokeInst& II); |
| void visitReturnInst(ReturnInst& RI); |
| void visitUnwindInst(UnwindInst& UI); |
| |
| bool run(Module& M); |
| bool doInitialization(Module& M); |
| }; |
| |
| RegisterOpt<LowerSetJmp> X("lowersetjmp", "Lower Set Jump"); |
| } // end anonymous namespace |
| |
| // run - Run the transformation on the program. We grab the function |
| // prototypes for longjmp and setjmp. If they are used in the program, |
| // then we can go directly to the places they're at and transform them. |
| bool LowerSetJmp::run(Module& M) |
| { |
| bool Changed = false; |
| |
| // These are what the functions are called. |
| Function* SetJmp = M.getNamedFunction("llvm.setjmp"); |
| Function* LongJmp = M.getNamedFunction("llvm.longjmp"); |
| |
| // This program doesn't have longjmp and setjmp calls. |
| if ((!LongJmp || LongJmp->use_empty()) && |
| (!SetJmp || SetJmp->use_empty())) return false; |
| |
| // Initialize some values and functions we'll need to transform the |
| // setjmp/longjmp functions. |
| doInitialization(M); |
| |
| if (SetJmp) { |
| for (Value::use_iterator B = SetJmp->use_begin(), E = SetJmp->use_end(); |
| B != E; ++B) { |
| BasicBlock* BB = cast<Instruction>(*B)->getParent(); |
| for (df_ext_iterator<BasicBlock*> I = df_ext_begin(BB, DFSBlocks), |
| E = df_ext_end(BB, DFSBlocks); I != E; ++I) |
| /* empty */; |
| } |
| |
| while (!SetJmp->use_empty()) { |
| assert(isa<CallInst>(SetJmp->use_back()) && |
| "User of setjmp intrinsic not a call?"); |
| TransformSetJmpCall(cast<CallInst>(SetJmp->use_back())); |
| Changed = true; |
| } |
| } |
| |
| if (LongJmp) |
| while (!LongJmp->use_empty()) { |
| assert(isa<CallInst>(LongJmp->use_back()) && |
| "User of longjmp intrinsic not a call?"); |
| TransformLongJmpCall(cast<CallInst>(LongJmp->use_back())); |
| Changed = true; |
| } |
| |
| // Now go through the affected functions and convert calls and invokes |
| // to new invokes... |
| for (std::map<Function*, AllocaInst*>::iterator |
| B = SJMap.begin(), E = SJMap.end(); B != E; ++B) { |
| Function* F = B->first; |
| for (Function::iterator BB = F->begin(), BE = F->end(); BB != BE; ++BB) |
| for (BasicBlock::iterator IB = BB->begin(), IE = BB->end(); IB != IE; ) { |
| visit(*IB++); |
| if (IB != BB->end() && IB->getParent() != BB) |
| break; // The next instruction got moved to a different block! |
| } |
| } |
| |
| DFSBlocks.clear(); |
| SJMap.clear(); |
| RethrowBBMap.clear(); |
| PrelimBBMap.clear(); |
| SwitchValMap.clear(); |
| SetJmpIDMap.clear(); |
| |
| return Changed; |
| } |
| |
| // doInitialization - For the lower long/setjmp pass, this ensures that a |
| // module contains a declaration for the intrisic functions we are going |
| // to call to convert longjmp and setjmp calls. |
| // |
| // This function is always successful, unless it isn't. |
| bool LowerSetJmp::doInitialization(Module& M) |
| { |
| const Type *SBPTy = PointerType::get(Type::SByteTy); |
| const Type *SBPPTy = PointerType::get(SBPTy); |
| |
| // N.B. See llvm/runtime/GCCLibraries/libexception/SJLJ-Exception.h for |
| // a description of the following library functions. |
| |
| // void __llvm_sjljeh_init_setjmpmap(void**) |
| InitSJMap = M.getOrInsertFunction("__llvm_sjljeh_init_setjmpmap", |
| Type::VoidTy, SBPPTy, 0); |
| // void __llvm_sjljeh_destroy_setjmpmap(void**) |
| DestroySJMap = M.getOrInsertFunction("__llvm_sjljeh_destroy_setjmpmap", |
| Type::VoidTy, SBPPTy, 0); |
| |
| // void __llvm_sjljeh_add_setjmp_to_map(void**, void*, unsigned) |
| AddSJToMap = M.getOrInsertFunction("__llvm_sjljeh_add_setjmp_to_map", |
| Type::VoidTy, SBPPTy, SBPTy, |
| Type::UIntTy, 0); |
| |
| // void __llvm_sjljeh_throw_longjmp(int*, int) |
| ThrowLongJmp = M.getOrInsertFunction("__llvm_sjljeh_throw_longjmp", |
| Type::VoidTy, SBPTy, Type::IntTy, 0); |
| |
| // unsigned __llvm_sjljeh_try_catching_longjmp_exception(void **) |
| TryCatchLJ = |
| M.getOrInsertFunction("__llvm_sjljeh_try_catching_longjmp_exception", |
| Type::UIntTy, SBPPTy, 0); |
| |
| // bool __llvm_sjljeh_is_longjmp_exception() |
| IsLJException = M.getOrInsertFunction("__llvm_sjljeh_is_longjmp_exception", |
| Type::BoolTy, 0); |
| |
| // int __llvm_sjljeh_get_longjmp_value() |
| GetLJValue = M.getOrInsertFunction("__llvm_sjljeh_get_longjmp_value", |
| Type::IntTy, 0); |
| return true; |
| } |
| |
| // IsTransformableFunction - Return true if the function name isn't one |
| // of the ones we don't want transformed. Currently, don't transform any |
| // "llvm.{setjmp,longjmp}" functions and none of the setjmp/longjmp error |
| // handling functions (beginning with __llvm_sjljeh_...they don't throw |
| // exceptions). |
| bool LowerSetJmp::IsTransformableFunction(const std::string& Name) |
| { |
| std::string SJLJEh("__llvm_sjljeh"); |
| |
| if (Name.size() > SJLJEh.size()) |
| return std::string(Name.begin(), Name.begin() + SJLJEh.size()) != SJLJEh; |
| |
| return true; |
| } |
| |
| // TransformLongJmpCall - Transform a longjmp call into a call to the |
| // internal __llvm_sjljeh_throw_longjmp function. It then takes care of |
| // throwing the exception for us. |
| void LowerSetJmp::TransformLongJmpCall(CallInst* Inst) |
| { |
| const Type* SBPTy = PointerType::get(Type::SByteTy); |
| |
| // Create the call to "__llvm_sjljeh_throw_longjmp". This takes the |
| // same parameters as "longjmp", except that the buffer is cast to a |
| // char*. It returns "void", so it doesn't need to replace any of |
| // Inst's uses and doesn't get a name. |
| CastInst* CI = new CastInst(Inst->getOperand(1), SBPTy, "LJBuf", Inst); |
| new CallInst(ThrowLongJmp, make_vector<Value*>(CI, Inst->getOperand(2), 0), |
| "", Inst); |
| |
| SwitchValuePair& SVP = SwitchValMap[Inst->getParent()->getParent()]; |
| |
| // If the function has a setjmp call in it (they are transformed first) |
| // we should branch to the basic block that determines if this longjmp |
| // is applicable here. Otherwise, issue an unwind. |
| if (SVP.first) |
| new BranchInst(SVP.first->getParent(), Inst); |
| else |
| new UnwindInst(Inst); |
| |
| // Remove all insts after the branch/unwind inst. |
| Inst->getParent()->getInstList().erase(Inst, |
| Inst->getParent()->getInstList().end()); |
| |
| ++LongJmpsTransformed; |
| } |
| |
| // GetSetJmpMap - Retrieve (create and initialize, if necessary) the |
| // setjmp map. This map is going to hold information about which setjmps |
| // were called (each setjmp gets its own number) and with which buffer it |
| // was called. There can be only one! |
| AllocaInst* LowerSetJmp::GetSetJmpMap(Function* Func) |
| { |
| if (SJMap[Func]) return SJMap[Func]; |
| |
| // Insert the setjmp map initialization before the first instruction in |
| // the function. |
| Instruction* Inst = Func->getEntryBlock().begin(); |
| assert(Inst && "Couldn't find even ONE instruction in entry block!"); |
| |
| // Fill in the alloca and call to initialize the SJ map. |
| const Type *SBPTy = PointerType::get(Type::SByteTy); |
| AllocaInst* Map = new AllocaInst(SBPTy, 0, "SJMap", Inst); |
| new CallInst(InitSJMap, make_vector<Value*>(Map, 0), "", Inst); |
| return SJMap[Func] = Map; |
| } |
| |
| // GetRethrowBB - Only one rethrow basic block is needed per function. |
| // If this is a longjmp exception but not handled in this block, this BB |
| // performs the rethrow. |
| BasicBlock* LowerSetJmp::GetRethrowBB(Function* Func) |
| { |
| if (RethrowBBMap[Func]) return RethrowBBMap[Func]; |
| |
| // The basic block we're going to jump to if we need to rethrow the |
| // exception. |
| BasicBlock* Rethrow = new BasicBlock("RethrowExcept", Func); |
| BasicBlock::InstListType& RethrowBlkIL = Rethrow->getInstList(); |
| |
| // Fill in the "Rethrow" BB with a call to rethrow the exception. This |
| // is the last instruction in the BB since at this point the runtime |
| // should exit this function and go to the next function. |
| RethrowBlkIL.push_back(new UnwindInst()); |
| return RethrowBBMap[Func] = Rethrow; |
| } |
| |
| // GetSJSwitch - Return the switch statement that controls which handler |
| // (if any) gets called and the value returned to that handler. |
| LowerSetJmp::SwitchValuePair LowerSetJmp::GetSJSwitch(Function* Func, |
| BasicBlock* Rethrow) |
| { |
| if (SwitchValMap[Func].first) return SwitchValMap[Func]; |
| |
| BasicBlock* LongJmpPre = new BasicBlock("LongJmpBlkPre", Func); |
| BasicBlock::InstListType& LongJmpPreIL = LongJmpPre->getInstList(); |
| |
| // Keep track of the preliminary basic block for some of the other |
| // transformations. |
| PrelimBBMap[Func] = LongJmpPre; |
| |
| // Grab the exception. |
| CallInst* Cond = new |
| CallInst(IsLJException, std::vector<Value*>(), "IsLJExcept"); |
| LongJmpPreIL.push_back(Cond); |
| |
| // The "decision basic block" gets the number associated with the |
| // setjmp call returning to switch on and the value returned by |
| // longjmp. |
| BasicBlock* DecisionBB = new BasicBlock("LJDecisionBB", Func); |
| BasicBlock::InstListType& DecisionBBIL = DecisionBB->getInstList(); |
| |
| LongJmpPreIL.push_back(new BranchInst(DecisionBB, Rethrow, Cond)); |
| |
| // Fill in the "decision" basic block. |
| CallInst* LJVal = new CallInst(GetLJValue, std::vector<Value*>(), "LJVal"); |
| DecisionBBIL.push_back(LJVal); |
| CallInst* SJNum = new |
| CallInst(TryCatchLJ, make_vector<Value*>(GetSetJmpMap(Func), 0), "SJNum"); |
| DecisionBBIL.push_back(SJNum); |
| |
| SwitchInst* SI = new SwitchInst(SJNum, Rethrow); |
| DecisionBBIL.push_back(SI); |
| return SwitchValMap[Func] = SwitchValuePair(SI, LJVal); |
| } |
| |
| // TransformSetJmpCall - The setjmp call is a bit trickier to transform. |
| // We're going to convert all setjmp calls to nops. Then all "call" and |
| // "invoke" instructions in the function are converted to "invoke" where |
| // the "except" branch is used when returning from a longjmp call. |
| void LowerSetJmp::TransformSetJmpCall(CallInst* Inst) |
| { |
| BasicBlock* ABlock = Inst->getParent(); |
| Function* Func = ABlock->getParent(); |
| |
| // Add this setjmp to the setjmp map. |
| const Type* SBPTy = PointerType::get(Type::SByteTy); |
| CastInst* BufPtr = new CastInst(Inst->getOperand(1), SBPTy, "SBJmpBuf", Inst); |
| new CallInst(AddSJToMap, |
| make_vector<Value*>(GetSetJmpMap(Func), BufPtr, |
| ConstantUInt::get(Type::UIntTy, |
| SetJmpIDMap[Func]++), 0), |
| "", Inst); |
| |
| // We are guaranteed that there are no values live across basic blocks |
| // (because we are "not in SSA form" yet), but there can still be values live |
| // in basic blocks. Because of this, splitting the setjmp block can cause |
| // values above the setjmp to not dominate uses which are after the setjmp |
| // call. For all of these occasions, we must spill the value to the stack. |
| // |
| std::set<Instruction*> InstrsAfterCall; |
| |
| // The call is probably very close to the end of the basic block, for the |
| // common usage pattern of: 'if (setjmp(...))', so keep track of the |
| // instructions after the call. |
| for (BasicBlock::iterator I = ++BasicBlock::iterator(Inst), E = ABlock->end(); |
| I != E; ++I) |
| InstrsAfterCall.insert(I); |
| |
| for (BasicBlock::iterator II = ABlock->begin(); |
| II != BasicBlock::iterator(Inst); ++II) |
| // Loop over all of the uses of instruction. If any of them are after the |
| // call, "spill" the value to the stack. |
| for (Value::use_iterator UI = II->use_begin(), E = II->use_end(); |
| UI != E; ++UI) |
| if (cast<Instruction>(*UI)->getParent() != ABlock || |
| InstrsAfterCall.count(cast<Instruction>(*UI))) { |
| DemoteRegToStack(*II); |
| break; |
| } |
| InstrsAfterCall.clear(); |
| |
| // Change the setjmp call into a branch statement. We'll remove the |
| // setjmp call in a little bit. No worries. |
| BasicBlock* SetJmpContBlock = ABlock->splitBasicBlock(Inst); |
| assert(SetJmpContBlock && "Couldn't split setjmp BB!!"); |
| |
| SetJmpContBlock->setName("SetJmpContBlock"); |
| |
| // Reposition the split BB in the BB list to make things tidier. |
| Func->getBasicBlockList().remove(SetJmpContBlock); |
| Func->getBasicBlockList().insert(++Function::iterator(ABlock), |
| SetJmpContBlock); |
| |
| // This PHI node will be in the new block created from the |
| // splitBasicBlock call. |
| PHINode* PHI = new PHINode(Type::IntTy, "SetJmpReturn", Inst); |
| |
| // Coming from a call to setjmp, the return is 0. |
| PHI->addIncoming(ConstantInt::getNullValue(Type::IntTy), ABlock); |
| |
| // Add the case for this setjmp's number... |
| SwitchValuePair SVP = GetSJSwitch(Func, GetRethrowBB(Func)); |
| SVP.first->addCase(ConstantUInt::get(Type::UIntTy, SetJmpIDMap[Func] - 1), |
| SetJmpContBlock); |
| |
| // Value coming from the handling of the exception. |
| PHI->addIncoming(SVP.second, SVP.second->getParent()); |
| |
| // Replace all uses of this instruction with the PHI node created by |
| // the eradication of setjmp. |
| Inst->replaceAllUsesWith(PHI); |
| Inst->getParent()->getInstList().erase(Inst); |
| |
| ++SetJmpsTransformed; |
| } |
| |
| // visitCallInst - This converts all LLVM call instructions into invoke |
| // instructions. The except part of the invoke goes to the "LongJmpBlkPre" |
| // that grabs the exception and proceeds to determine if it's a longjmp |
| // exception or not. |
| void LowerSetJmp::visitCallInst(CallInst& CI) |
| { |
| if (CI.getCalledFunction()) |
| if (!IsTransformableFunction(CI.getCalledFunction()->getName()) || |
| CI.getCalledFunction()->isIntrinsic()) return; |
| |
| BasicBlock* OldBB = CI.getParent(); |
| |
| // If not reachable from a setjmp call, don't transform. |
| if (!DFSBlocks.count(OldBB)) return; |
| |
| BasicBlock* NewBB = OldBB->splitBasicBlock(CI); |
| assert(NewBB && "Couldn't split BB of \"call\" instruction!!"); |
| NewBB->setName("Call2Invoke"); |
| |
| // Reposition the split BB in the BB list to make things tidier. |
| Function* Func = OldBB->getParent(); |
| Func->getBasicBlockList().remove(NewBB); |
| Func->getBasicBlockList().insert(++Function::iterator(OldBB), NewBB); |
| |
| // Construct the new "invoke" instruction. |
| TerminatorInst* Term = OldBB->getTerminator(); |
| std::vector<Value*> Params(CI.op_begin() + 1, CI.op_end()); |
| InvokeInst* II = new |
| InvokeInst(CI.getCalledValue(), NewBB, PrelimBBMap[Func], |
| Params, CI.getName(), Term); |
| |
| // Replace the old call inst with the invoke inst and remove the call. |
| CI.replaceAllUsesWith(II); |
| CI.getParent()->getInstList().erase(&CI); |
| |
| // The old terminator is useless now that we have the invoke inst. |
| Term->getParent()->getInstList().erase(Term); |
| ++CallsTransformed; |
| } |
| |
| // visitInvokeInst - Converting the "invoke" instruction is fairly |
| // straight-forward. The old exception part is replaced by a query asking |
| // if this is a longjmp exception. If it is, then it goes to the longjmp |
| // exception blocks. Otherwise, control is passed the old exception. |
| void LowerSetJmp::visitInvokeInst(InvokeInst& II) |
| { |
| if (II.getCalledFunction()) |
| if (!IsTransformableFunction(II.getCalledFunction()->getName()) || |
| II.getCalledFunction()->isIntrinsic()) return; |
| |
| BasicBlock* BB = II.getParent(); |
| |
| // If not reachable from a setjmp call, don't transform. |
| if (!DFSBlocks.count(BB)) return; |
| |
| BasicBlock* NormalBB = II.getNormalDest(); |
| BasicBlock* ExceptBB = II.getExceptionalDest(); |
| |
| Function* Func = BB->getParent(); |
| BasicBlock* NewExceptBB = new BasicBlock("InvokeExcept", Func); |
| BasicBlock::InstListType& InstList = NewExceptBB->getInstList(); |
| |
| // If this is a longjmp exception, then branch to the preliminary BB of |
| // the longjmp exception handling. Otherwise, go to the old exception. |
| CallInst* IsLJExcept = new |
| CallInst(IsLJException, std::vector<Value*>(), "IsLJExcept"); |
| InstList.push_back(IsLJExcept); |
| |
| BranchInst* BR = new BranchInst(PrelimBBMap[Func], ExceptBB, IsLJExcept); |
| InstList.push_back(BR); |
| |
| II.setExceptionalDest(NewExceptBB); |
| ++InvokesTransformed; |
| } |
| |
| // visitReturnInst - We want to destroy the setjmp map upon exit from the |
| // function. |
| void LowerSetJmp::visitReturnInst(ReturnInst& RI) |
| { |
| Function* Func = RI.getParent()->getParent(); |
| new CallInst(DestroySJMap, make_vector<Value*>(GetSetJmpMap(Func), 0), |
| "", &RI); |
| } |
| |
| // visitUnwindInst - We want to destroy the setjmp map upon exit from the |
| // function. |
| void LowerSetJmp::visitUnwindInst(UnwindInst& UI) |
| { |
| Function* Func = UI.getParent()->getParent(); |
| new CallInst(DestroySJMap, make_vector<Value*>(GetSetJmpMap(Func), 0), |
| "", &UI); |
| } |
| |
| Pass* createLowerSetJmpPass() |
| { |
| return new LowerSetJmp(); |
| } |
| |
| } // End llvm namespace |