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575 lines
24 KiB
C++
575 lines
24 KiB
C++
//===- LowerInvoke.cpp - Eliminate Invoke & Unwind instructions -----------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This transformation is designed for use by code generators which do not yet
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// support stack unwinding. This pass supports two models of exception handling
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// lowering, the 'cheap' support and the 'expensive' support.
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//
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// 'Cheap' exception handling support gives the program the ability to execute
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// any program which does not "throw an exception", by turning 'invoke'
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// instructions into calls and by turning 'unwind' instructions into calls to
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// abort(). If the program does dynamically use the unwind instruction, the
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// program will print a message then abort.
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//
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// 'Expensive' exception handling support gives the full exception handling
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// support to the program at the cost of making the 'invoke' instruction
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// really expensive. It basically inserts setjmp/longjmp calls to emulate the
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// exception handling as necessary.
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//
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// Because the 'expensive' support slows down programs a lot, and EH is only
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// used for a subset of the programs, it must be specifically enabled by an
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// option.
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//
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// Note that after this pass runs the CFG is not entirely accurate (exceptional
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// control flow edges are not correct anymore) so only very simple things should
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// be done after the lowerinvoke pass has run (like generation of native code).
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// This should not be used as a general purpose "my LLVM-to-LLVM pass doesn't
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// support the invoke instruction yet" lowering pass.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "lowerinvoke"
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Constants.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/Instructions.h"
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#include "llvm/Module.h"
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#include "llvm/Pass.h"
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#include "llvm/Transforms/Utils/BasicBlockUtils.h"
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#include "llvm/Transforms/Utils/Local.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/Target/TargetLowering.h"
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#include <csetjmp>
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using namespace llvm;
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STATISTIC(NumInvokes, "Number of invokes replaced");
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STATISTIC(NumUnwinds, "Number of unwinds replaced");
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STATISTIC(NumSpilled, "Number of registers live across unwind edges");
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static cl::opt<bool> ExpensiveEHSupport("enable-correct-eh-support",
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cl::desc("Make the -lowerinvoke pass insert expensive, but correct, EH code"));
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namespace {
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class VISIBILITY_HIDDEN LowerInvoke : public FunctionPass {
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// Used for both models.
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Constant *WriteFn;
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Constant *AbortFn;
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Value *AbortMessage;
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unsigned AbortMessageLength;
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// Used for expensive EH support.
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const Type *JBLinkTy;
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GlobalVariable *JBListHead;
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Constant *SetJmpFn, *LongJmpFn;
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// We peek in TLI to grab the target's jmp_buf size and alignment
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const TargetLowering *TLI;
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public:
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LowerInvoke(const TargetLowering *tli = NULL) : TLI(tli) { }
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bool doInitialization(Module &M);
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bool runOnFunction(Function &F);
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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// This is a cluster of orthogonal Transforms
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AU.addPreservedID(PromoteMemoryToRegisterID);
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AU.addPreservedID(LowerSelectID);
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AU.addPreservedID(LowerSwitchID);
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AU.addPreservedID(LowerAllocationsID);
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}
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private:
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void createAbortMessage(Module *M);
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void writeAbortMessage(Instruction *IB);
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bool insertCheapEHSupport(Function &F);
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void splitLiveRangesLiveAcrossInvokes(std::vector<InvokeInst*> &Invokes);
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void rewriteExpensiveInvoke(InvokeInst *II, unsigned InvokeNo,
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AllocaInst *InvokeNum, SwitchInst *CatchSwitch);
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bool insertExpensiveEHSupport(Function &F);
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};
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RegisterPass<LowerInvoke>
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X("lowerinvoke", "Lower invoke and unwind, for unwindless code generators");
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}
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const PassInfo *llvm::LowerInvokePassID = X.getPassInfo();
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// Public Interface To the LowerInvoke pass.
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FunctionPass *llvm::createLowerInvokePass(const TargetLowering *TLI) {
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return new LowerInvoke(TLI);
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}
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// doInitialization - Make sure that there is a prototype for abort in the
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// current module.
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bool LowerInvoke::doInitialization(Module &M) {
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const Type *VoidPtrTy = PointerType::get(Type::Int8Ty);
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AbortMessage = 0;
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if (ExpensiveEHSupport) {
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// Insert a type for the linked list of jump buffers.
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unsigned JBSize = TLI ? TLI->getJumpBufSize() : 0;
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JBSize = JBSize ? JBSize : 200;
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const Type *JmpBufTy = ArrayType::get(VoidPtrTy, JBSize);
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{ // The type is recursive, so use a type holder.
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std::vector<const Type*> Elements;
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Elements.push_back(JmpBufTy);
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OpaqueType *OT = OpaqueType::get();
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Elements.push_back(PointerType::get(OT));
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PATypeHolder JBLType(StructType::get(Elements));
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OT->refineAbstractTypeTo(JBLType.get()); // Complete the cycle.
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JBLinkTy = JBLType.get();
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M.addTypeName("llvm.sjljeh.jmpbufty", JBLinkTy);
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}
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const Type *PtrJBList = PointerType::get(JBLinkTy);
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// Now that we've done that, insert the jmpbuf list head global, unless it
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// already exists.
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if (!(JBListHead = M.getGlobalVariable("llvm.sjljeh.jblist", PtrJBList))) {
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JBListHead = new GlobalVariable(PtrJBList, false,
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GlobalValue::LinkOnceLinkage,
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Constant::getNullValue(PtrJBList),
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"llvm.sjljeh.jblist", &M);
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}
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SetJmpFn = M.getOrInsertFunction("llvm.setjmp", Type::Int32Ty,
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PointerType::get(JmpBufTy), (Type *)0);
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LongJmpFn = M.getOrInsertFunction("llvm.longjmp", Type::VoidTy,
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PointerType::get(JmpBufTy),
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Type::Int32Ty, (Type *)0);
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}
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// We need the 'write' and 'abort' functions for both models.
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AbortFn = M.getOrInsertFunction("abort", Type::VoidTy, (Type *)0);
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WriteFn = M.getOrInsertFunction("write", Type::VoidTy, Type::Int32Ty,
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VoidPtrTy, Type::Int32Ty, (Type *)0);
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return true;
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}
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void LowerInvoke::createAbortMessage(Module *M) {
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if (ExpensiveEHSupport) {
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// The abort message for expensive EH support tells the user that the
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// program 'unwound' without an 'invoke' instruction.
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Constant *Msg =
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ConstantArray::get("ERROR: Exception thrown, but not caught!\n");
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AbortMessageLength = Msg->getNumOperands()-1; // don't include \0
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GlobalVariable *MsgGV = new GlobalVariable(Msg->getType(), true,
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GlobalValue::InternalLinkage,
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Msg, "abortmsg", M);
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std::vector<Constant*> GEPIdx(2, Constant::getNullValue(Type::Int32Ty));
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AbortMessage = ConstantExpr::getGetElementPtr(MsgGV, GEPIdx);
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} else {
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// The abort message for cheap EH support tells the user that EH is not
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// enabled.
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Constant *Msg =
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ConstantArray::get("Exception handler needed, but not enabled. Recompile"
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" program with -enable-correct-eh-support.\n");
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AbortMessageLength = Msg->getNumOperands()-1; // don't include \0
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GlobalVariable *MsgGV = new GlobalVariable(Msg->getType(), true,
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GlobalValue::InternalLinkage,
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Msg, "abortmsg", M);
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std::vector<Constant*> GEPIdx(2, Constant::getNullValue(Type::Int32Ty));
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AbortMessage = ConstantExpr::getGetElementPtr(MsgGV, GEPIdx);
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}
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}
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void LowerInvoke::writeAbortMessage(Instruction *IB) {
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if (AbortMessage == 0)
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createAbortMessage(IB->getParent()->getParent()->getParent());
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// These are the arguments we WANT...
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std::vector<Value*> Args;
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Args.push_back(ConstantInt::get(Type::Int32Ty, 2));
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Args.push_back(AbortMessage);
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Args.push_back(ConstantInt::get(Type::Int32Ty, AbortMessageLength));
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(new CallInst(WriteFn, Args, "", IB))->setTailCall();
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}
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bool LowerInvoke::insertCheapEHSupport(Function &F) {
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bool Changed = false;
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for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
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if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
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// Insert a normal call instruction...
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std::string Name = II->getName(); II->setName("");
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CallInst *NewCall = new CallInst(II->getCalledValue(),
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std::vector<Value*>(II->op_begin()+3,
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II->op_end()), Name, II);
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NewCall->setCallingConv(II->getCallingConv());
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II->replaceAllUsesWith(NewCall);
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// Insert an unconditional branch to the normal destination.
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new BranchInst(II->getNormalDest(), II);
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// Remove any PHI node entries from the exception destination.
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II->getUnwindDest()->removePredecessor(BB);
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// Remove the invoke instruction now.
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BB->getInstList().erase(II);
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++NumInvokes; Changed = true;
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} else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) {
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// Insert a new call to write(2, AbortMessage, AbortMessageLength);
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writeAbortMessage(UI);
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// Insert a call to abort()
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(new CallInst(AbortFn, std::vector<Value*>(), "", UI))->setTailCall();
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// Insert a return instruction. This really should be a "barrier", as it
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// is unreachable.
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new ReturnInst(F.getReturnType() == Type::VoidTy ? 0 :
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Constant::getNullValue(F.getReturnType()), UI);
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// Remove the unwind instruction now.
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BB->getInstList().erase(UI);
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++NumUnwinds; Changed = true;
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}
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return Changed;
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}
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/// rewriteExpensiveInvoke - Insert code and hack the function to replace the
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/// specified invoke instruction with a call.
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void LowerInvoke::rewriteExpensiveInvoke(InvokeInst *II, unsigned InvokeNo,
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AllocaInst *InvokeNum,
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SwitchInst *CatchSwitch) {
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ConstantInt *InvokeNoC = ConstantInt::get(Type::Int32Ty, InvokeNo);
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// Insert a store of the invoke num before the invoke and store zero into the
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// location afterward.
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new StoreInst(InvokeNoC, InvokeNum, true, II); // volatile
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BasicBlock::iterator NI = II->getNormalDest()->begin();
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while (isa<PHINode>(NI)) ++NI;
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// nonvolatile.
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new StoreInst(Constant::getNullValue(Type::Int32Ty), InvokeNum, false, NI);
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// Add a switch case to our unwind block.
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CatchSwitch->addCase(InvokeNoC, II->getUnwindDest());
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// Insert a normal call instruction.
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std::string Name = II->getName(); II->setName("");
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CallInst *NewCall = new CallInst(II->getCalledValue(),
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std::vector<Value*>(II->op_begin()+3,
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II->op_end()), Name,
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II);
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NewCall->setCallingConv(II->getCallingConv());
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II->replaceAllUsesWith(NewCall);
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// Replace the invoke with an uncond branch.
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new BranchInst(II->getNormalDest(), NewCall->getParent());
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II->eraseFromParent();
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}
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/// MarkBlocksLiveIn - Insert BB and all of its predescessors into LiveBBs until
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/// we reach blocks we've already seen.
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static void MarkBlocksLiveIn(BasicBlock *BB, std::set<BasicBlock*> &LiveBBs) {
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if (!LiveBBs.insert(BB).second) return; // already been here.
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for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
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MarkBlocksLiveIn(*PI, LiveBBs);
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}
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// First thing we need to do is scan the whole function for values that are
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// live across unwind edges. Each value that is live across an unwind edge
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// we spill into a stack location, guaranteeing that there is nothing live
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// across the unwind edge. This process also splits all critical edges
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// coming out of invoke's.
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void LowerInvoke::
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splitLiveRangesLiveAcrossInvokes(std::vector<InvokeInst*> &Invokes) {
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// First step, split all critical edges from invoke instructions.
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for (unsigned i = 0, e = Invokes.size(); i != e; ++i) {
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InvokeInst *II = Invokes[i];
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SplitCriticalEdge(II, 0, this);
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SplitCriticalEdge(II, 1, this);
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assert(!isa<PHINode>(II->getNormalDest()) &&
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!isa<PHINode>(II->getUnwindDest()) &&
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"critical edge splitting left single entry phi nodes?");
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}
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Function *F = Invokes.back()->getParent()->getParent();
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// To avoid having to handle incoming arguments specially, we lower each arg
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// to a copy instruction in the entry block. This ensures that the argument
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// value itself cannot be live across the entry block.
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BasicBlock::iterator AfterAllocaInsertPt = F->begin()->begin();
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while (isa<AllocaInst>(AfterAllocaInsertPt) &&
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isa<ConstantInt>(cast<AllocaInst>(AfterAllocaInsertPt)->getArraySize()))
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++AfterAllocaInsertPt;
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for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
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AI != E; ++AI) {
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// This is always a no-op cast because we're casting AI to AI->getType() so
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// src and destination types are identical. BitCast is the only possibility.
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CastInst *NC = new BitCastInst(
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AI, AI->getType(), AI->getName()+".tmp", AfterAllocaInsertPt);
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AI->replaceAllUsesWith(NC);
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// Normally its is forbidden to replace a CastInst's operand because it
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// could cause the opcode to reflect an illegal conversion. However, we're
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// replacing it here with the same value it was constructed with to simply
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// make NC its user.
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NC->setOperand(0, AI);
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}
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// Finally, scan the code looking for instructions with bad live ranges.
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for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
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for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ++II) {
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// Ignore obvious cases we don't have to handle. In particular, most
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// instructions either have no uses or only have a single use inside the
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// current block. Ignore them quickly.
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Instruction *Inst = II;
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if (Inst->use_empty()) continue;
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if (Inst->hasOneUse() &&
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cast<Instruction>(Inst->use_back())->getParent() == BB &&
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!isa<PHINode>(Inst->use_back())) continue;
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// If this is an alloca in the entry block, it's not a real register
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// value.
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if (AllocaInst *AI = dyn_cast<AllocaInst>(Inst))
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if (isa<ConstantInt>(AI->getArraySize()) && BB == F->begin())
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continue;
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// Avoid iterator invalidation by copying users to a temporary vector.
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std::vector<Instruction*> Users;
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for (Value::use_iterator UI = Inst->use_begin(), E = Inst->use_end();
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UI != E; ++UI) {
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Instruction *User = cast<Instruction>(*UI);
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if (User->getParent() != BB || isa<PHINode>(User))
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Users.push_back(User);
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}
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// Scan all of the uses and see if the live range is live across an unwind
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// edge. If we find a use live across an invoke edge, create an alloca
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// and spill the value.
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std::set<InvokeInst*> InvokesWithStoreInserted;
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// Find all of the blocks that this value is live in.
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std::set<BasicBlock*> LiveBBs;
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LiveBBs.insert(Inst->getParent());
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while (!Users.empty()) {
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Instruction *U = Users.back();
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Users.pop_back();
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if (!isa<PHINode>(U)) {
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MarkBlocksLiveIn(U->getParent(), LiveBBs);
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} else {
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// Uses for a PHI node occur in their predecessor block.
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PHINode *PN = cast<PHINode>(U);
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for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
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if (PN->getIncomingValue(i) == Inst)
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MarkBlocksLiveIn(PN->getIncomingBlock(i), LiveBBs);
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}
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}
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// Now that we know all of the blocks that this thing is live in, see if
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// it includes any of the unwind locations.
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bool NeedsSpill = false;
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for (unsigned i = 0, e = Invokes.size(); i != e; ++i) {
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BasicBlock *UnwindBlock = Invokes[i]->getUnwindDest();
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if (UnwindBlock != BB && LiveBBs.count(UnwindBlock)) {
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NeedsSpill = true;
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}
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}
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// If we decided we need a spill, do it.
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if (NeedsSpill) {
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++NumSpilled;
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DemoteRegToStack(*Inst, true);
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}
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}
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}
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bool LowerInvoke::insertExpensiveEHSupport(Function &F) {
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std::vector<ReturnInst*> Returns;
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std::vector<UnwindInst*> Unwinds;
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std::vector<InvokeInst*> Invokes;
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for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
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if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) {
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// Remember all return instructions in case we insert an invoke into this
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// function.
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Returns.push_back(RI);
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} else if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
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Invokes.push_back(II);
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} else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) {
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Unwinds.push_back(UI);
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}
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if (Unwinds.empty() && Invokes.empty()) return false;
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NumInvokes += Invokes.size();
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NumUnwinds += Unwinds.size();
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// TODO: This is not an optimal way to do this. In particular, this always
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// inserts setjmp calls into the entries of functions with invoke instructions
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// even though there are possibly paths through the function that do not
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// execute any invokes. In particular, for functions with early exits, e.g.
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// the 'addMove' method in hexxagon, it would be nice to not have to do the
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// setjmp stuff on the early exit path. This requires a bit of dataflow, but
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// would not be too hard to do.
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// If we have an invoke instruction, insert a setjmp that dominates all
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// invokes. After the setjmp, use a cond branch that goes to the original
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// code path on zero, and to a designated 'catch' block of nonzero.
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Value *OldJmpBufPtr = 0;
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if (!Invokes.empty()) {
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// First thing we need to do is scan the whole function for values that are
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// live across unwind edges. Each value that is live across an unwind edge
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// we spill into a stack location, guaranteeing that there is nothing live
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// across the unwind edge. This process also splits all critical edges
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// coming out of invoke's.
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splitLiveRangesLiveAcrossInvokes(Invokes);
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BasicBlock *EntryBB = F.begin();
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// Create an alloca for the incoming jump buffer ptr and the new jump buffer
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// that needs to be restored on all exits from the function. This is an
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// alloca because the value needs to be live across invokes.
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unsigned Align = TLI ? TLI->getJumpBufAlignment() : 0;
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AllocaInst *JmpBuf =
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new AllocaInst(JBLinkTy, 0, Align, "jblink", F.begin()->begin());
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std::vector<Value*> Idx;
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Idx.push_back(Constant::getNullValue(Type::Int32Ty));
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|
Idx.push_back(ConstantInt::get(Type::Int32Ty, 1));
|
|
OldJmpBufPtr = new GetElementPtrInst(JmpBuf, Idx, "OldBuf",
|
|
EntryBB->getTerminator());
|
|
|
|
// Copy the JBListHead to the alloca.
|
|
Value *OldBuf = new LoadInst(JBListHead, "oldjmpbufptr", true,
|
|
EntryBB->getTerminator());
|
|
new StoreInst(OldBuf, OldJmpBufPtr, true, EntryBB->getTerminator());
|
|
|
|
// Add the new jumpbuf to the list.
|
|
new StoreInst(JmpBuf, JBListHead, true, EntryBB->getTerminator());
|
|
|
|
// Create the catch block. The catch block is basically a big switch
|
|
// statement that goes to all of the invoke catch blocks.
|
|
BasicBlock *CatchBB = new BasicBlock("setjmp.catch", &F);
|
|
|
|
// Create an alloca which keeps track of which invoke is currently
|
|
// executing. For normal calls it contains zero.
|
|
AllocaInst *InvokeNum = new AllocaInst(Type::Int32Ty, 0, "invokenum",
|
|
EntryBB->begin());
|
|
new StoreInst(ConstantInt::get(Type::Int32Ty, 0), InvokeNum, true,
|
|
EntryBB->getTerminator());
|
|
|
|
// 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 *UnwindBB = new BasicBlock("unwindbb", &F);
|
|
Unwinds.push_back(new UnwindInst(UnwindBB));
|
|
|
|
Value *CatchLoad = new LoadInst(InvokeNum, "invoke.num", true, CatchBB);
|
|
SwitchInst *CatchSwitch =
|
|
new SwitchInst(CatchLoad, UnwindBB, Invokes.size(), CatchBB);
|
|
|
|
// Now that things are set up, insert the setjmp call itself.
|
|
|
|
// Split the entry block to insert the conditional branch for the setjmp.
|
|
BasicBlock *ContBlock = EntryBB->splitBasicBlock(EntryBB->getTerminator(),
|
|
"setjmp.cont");
|
|
|
|
Idx[1] = ConstantInt::get(Type::Int32Ty, 0);
|
|
Value *JmpBufPtr = new GetElementPtrInst(JmpBuf, Idx, "TheJmpBuf",
|
|
EntryBB->getTerminator());
|
|
Value *SJRet = new CallInst(SetJmpFn, JmpBufPtr, "sjret",
|
|
EntryBB->getTerminator());
|
|
|
|
// Compare the return value to zero.
|
|
Value *IsNormal = new ICmpInst(ICmpInst::ICMP_EQ, SJRet,
|
|
Constant::getNullValue(SJRet->getType()),
|
|
"notunwind", EntryBB->getTerminator());
|
|
// Nuke the uncond branch.
|
|
EntryBB->getTerminator()->eraseFromParent();
|
|
|
|
// Put in a new condbranch in its place.
|
|
new BranchInst(ContBlock, CatchBB, IsNormal, EntryBB);
|
|
|
|
// At this point, we are all set up, rewrite each invoke instruction.
|
|
for (unsigned i = 0, e = Invokes.size(); i != e; ++i)
|
|
rewriteExpensiveInvoke(Invokes[i], i+1, InvokeNum, CatchSwitch);
|
|
}
|
|
|
|
// We know that there is at least one unwind.
|
|
|
|
// Create three new blocks, the block to load the jmpbuf ptr and compare
|
|
// against null, the block to do the longjmp, and the error block for if it
|
|
// is null. Add them at the end of the function because they are not hot.
|
|
BasicBlock *UnwindHandler = new BasicBlock("dounwind", &F);
|
|
BasicBlock *UnwindBlock = new BasicBlock("unwind", &F);
|
|
BasicBlock *TermBlock = new BasicBlock("unwinderror", &F);
|
|
|
|
// If this function contains an invoke, restore the old jumpbuf ptr.
|
|
Value *BufPtr;
|
|
if (OldJmpBufPtr) {
|
|
// Before the return, insert a copy from the saved value to the new value.
|
|
BufPtr = new LoadInst(OldJmpBufPtr, "oldjmpbufptr", UnwindHandler);
|
|
new StoreInst(BufPtr, JBListHead, UnwindHandler);
|
|
} else {
|
|
BufPtr = new LoadInst(JBListHead, "ehlist", UnwindHandler);
|
|
}
|
|
|
|
// Load the JBList, if it's null, then there was no catch!
|
|
Value *NotNull = new ICmpInst(ICmpInst::ICMP_NE, BufPtr,
|
|
Constant::getNullValue(BufPtr->getType()),
|
|
"notnull", UnwindHandler);
|
|
new BranchInst(UnwindBlock, TermBlock, NotNull, UnwindHandler);
|
|
|
|
// Create the block to do the longjmp.
|
|
// Get a pointer to the jmpbuf and longjmp.
|
|
std::vector<Value*> Idx;
|
|
Idx.push_back(Constant::getNullValue(Type::Int32Ty));
|
|
Idx.push_back(ConstantInt::get(Type::Int32Ty, 0));
|
|
Idx[0] = new GetElementPtrInst(BufPtr, Idx, "JmpBuf", UnwindBlock);
|
|
Idx[1] = ConstantInt::get(Type::Int32Ty, 1);
|
|
new CallInst(LongJmpFn, Idx, "", UnwindBlock);
|
|
new UnreachableInst(UnwindBlock);
|
|
|
|
// Set up the term block ("throw without a catch").
|
|
new UnreachableInst(TermBlock);
|
|
|
|
// Insert a new call to write(2, AbortMessage, AbortMessageLength);
|
|
writeAbortMessage(TermBlock->getTerminator());
|
|
|
|
// Insert a call to abort()
|
|
(new CallInst(AbortFn, std::vector<Value*>(), "",
|
|
TermBlock->getTerminator()))->setTailCall();
|
|
|
|
|
|
// Replace all unwinds with a branch to the unwind handler.
|
|
for (unsigned i = 0, e = Unwinds.size(); i != e; ++i) {
|
|
new BranchInst(UnwindHandler, Unwinds[i]);
|
|
Unwinds[i]->eraseFromParent();
|
|
}
|
|
|
|
// Finally, for any returns from this function, if this function contains an
|
|
// invoke, restore the old jmpbuf pointer to its input value.
|
|
if (OldJmpBufPtr) {
|
|
for (unsigned i = 0, e = Returns.size(); i != e; ++i) {
|
|
ReturnInst *R = Returns[i];
|
|
|
|
// Before the return, insert a copy from the saved value to the new value.
|
|
Value *OldBuf = new LoadInst(OldJmpBufPtr, "oldjmpbufptr", true, R);
|
|
new StoreInst(OldBuf, JBListHead, true, R);
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
bool LowerInvoke::runOnFunction(Function &F) {
|
|
if (ExpensiveEHSupport)
|
|
return insertExpensiveEHSupport(F);
|
|
else
|
|
return insertCheapEHSupport(F);
|
|
}
|