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+//===- LowerInvoke.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 do not yet
+// support stack unwinding. This pass supports two models of exception handling
+// lowering, the 'cheap' support and the 'expensive' support.
+//
+// 'Cheap' exception handling support gives the program the ability to execute
+// any program which does not "throw an exception", by turning 'invoke'
+// instructions into calls and by turning 'unwind' instructions into calls to
+// abort(). If the program does dynamically use the unwind instruction, the
+// program will print a message then abort.
+//
+// 'Expensive' exception handling support gives the full exception handling
+// support to the program at the cost of making the 'invoke' instruction
+// really expensive. It basically inserts setjmp/longjmp calls to emulate the
+// exception handling as necessary.
+//
+// Because the 'expensive' support slows down programs a lot, and EH is only
+// used for a subset of the programs, it must be specifically enabled by an
+// option.
+//
+// Note that after this pass runs the CFG is not entirely accurate (exceptional
+// control flow edges are not correct anymore) so only very simple things should
+// be done after the lowerinvoke pass has run (like generation of native code).
+// This should not be used as a general purpose "my LLVM-to-LLVM pass doesn't
+// support the invoke instruction yet" lowering pass.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "lowerinvoke"
+#include "llvm/Transforms/Scalar.h"
+#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/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/Target/TargetLowering.h"
+#include <csetjmp>
+#include <set>
+using namespace llvm;
+
+STATISTIC(NumInvokes, "Number of invokes replaced");
+STATISTIC(NumUnwinds, "Number of unwinds replaced");
+STATISTIC(NumSpilled, "Number of registers live across unwind edges");
+
+static cl::opt<bool> ExpensiveEHSupport("enable-correct-eh-support",
+ cl::desc("Make the -lowerinvoke pass insert expensive, but correct, EH code"));
+
+namespace {
+ class VISIBILITY_HIDDEN LowerInvoke : public FunctionPass {
+ // Used for both models.
+ Constant *WriteFn;
+ Constant *AbortFn;
+ Value *AbortMessage;
+ unsigned AbortMessageLength;
+
+ // Used for expensive EH support.
+ const Type *JBLinkTy;
+ GlobalVariable *JBListHead;
+ Constant *SetJmpFn, *LongJmpFn;
+
+ // We peek in TLI to grab the target's jmp_buf size and alignment
+ const TargetLowering *TLI;
+
+ public:
+ static char ID; // Pass identification, replacement for typeid
+ explicit LowerInvoke(const TargetLowering *tli = NULL)
+ : FunctionPass(&ID), TLI(tli) { }
+ bool doInitialization(Module &M);
+ bool runOnFunction(Function &F);
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ // This is a cluster of orthogonal Transforms
+ AU.addPreservedID(PromoteMemoryToRegisterID);
+ AU.addPreservedID(LowerSwitchID);
+ AU.addPreservedID(LowerAllocationsID);
+ }
+
+ private:
+ void createAbortMessage(Module *M);
+ void writeAbortMessage(Instruction *IB);
+ bool insertCheapEHSupport(Function &F);
+ void splitLiveRangesLiveAcrossInvokes(std::vector<InvokeInst*> &Invokes);
+ void rewriteExpensiveInvoke(InvokeInst *II, unsigned InvokeNo,
+ AllocaInst *InvokeNum, SwitchInst *CatchSwitch);
+ bool insertExpensiveEHSupport(Function &F);
+ };
+}
+
+char LowerInvoke::ID = 0;
+static RegisterPass<LowerInvoke>
+X("lowerinvoke", "Lower invoke and unwind, for unwindless code generators");
+
+const PassInfo *const llvm::LowerInvokePassID = &X;
+
+// Public Interface To the LowerInvoke pass.
+FunctionPass *llvm::createLowerInvokePass(const TargetLowering *TLI) {
+ return new LowerInvoke(TLI);
+}
+
+// doInitialization - Make sure that there is a prototype for abort in the
+// current module.
+bool LowerInvoke::doInitialization(Module &M) {
+ const Type *VoidPtrTy = PointerType::getUnqual(Type::Int8Ty);
+ AbortMessage = 0;
+ if (ExpensiveEHSupport) {
+ // Insert a type for the linked list of jump buffers.
+ unsigned JBSize = TLI ? TLI->getJumpBufSize() : 0;
+ JBSize = JBSize ? JBSize : 200;
+ const Type *JmpBufTy = ArrayType::get(VoidPtrTy, JBSize);
+
+ { // The type is recursive, so use a type holder.
+ std::vector<const Type*> Elements;
+ Elements.push_back(JmpBufTy);
+ OpaqueType *OT = OpaqueType::get();
+ Elements.push_back(PointerType::getUnqual(OT));
+ PATypeHolder JBLType(StructType::get(Elements));
+ OT->refineAbstractTypeTo(JBLType.get()); // Complete the cycle.
+ JBLinkTy = JBLType.get();
+ M.addTypeName("llvm.sjljeh.jmpbufty", JBLinkTy);
+ }
+
+ const Type *PtrJBList = PointerType::getUnqual(JBLinkTy);
+
+ // Now that we've done that, insert the jmpbuf list head global, unless it
+ // already exists.
+ if (!(JBListHead = M.getGlobalVariable("llvm.sjljeh.jblist", PtrJBList))) {
+ JBListHead = new GlobalVariable(PtrJBList, false,
+ GlobalValue::LinkOnceAnyLinkage,
+ Constant::getNullValue(PtrJBList),
+ "llvm.sjljeh.jblist", &M);
+ }
+
+// VisualStudio defines setjmp as _setjmp via #include <csetjmp> / <setjmp.h>,
+// so it looks like Intrinsic::_setjmp
+#if defined(_MSC_VER) && defined(setjmp)
+#define setjmp_undefined_for_visual_studio
+#undef setjmp
+#endif
+
+ SetJmpFn = Intrinsic::getDeclaration(&M, Intrinsic::setjmp);
+
+#if defined(_MSC_VER) && defined(setjmp_undefined_for_visual_studio)
+// let's return it to _setjmp state in case anyone ever needs it after this
+// point under VisualStudio
+#define setjmp _setjmp
+#endif
+
+ LongJmpFn = Intrinsic::getDeclaration(&M, Intrinsic::longjmp);
+ }
+
+ // We need the 'write' and 'abort' functions for both models.
+ AbortFn = M.getOrInsertFunction("abort", Type::VoidTy, (Type *)0);
+#if 0 // "write" is Unix-specific.. code is going away soon anyway.
+ WriteFn = M.getOrInsertFunction("write", Type::VoidTy, Type::Int32Ty,
+ VoidPtrTy, Type::Int32Ty, (Type *)0);
+#else
+ WriteFn = 0;
+#endif
+ return true;
+}
+
+void LowerInvoke::createAbortMessage(Module *M) {
+ if (ExpensiveEHSupport) {
+ // The abort message for expensive EH support tells the user that the
+ // program 'unwound' without an 'invoke' instruction.
+ Constant *Msg =
+ ConstantArray::get("ERROR: Exception thrown, but not caught!\n");
+ AbortMessageLength = Msg->getNumOperands()-1; // don't include \0
+
+ GlobalVariable *MsgGV = new GlobalVariable(Msg->getType(), true,
+ GlobalValue::InternalLinkage,
+ Msg, "abortmsg", M);
+ std::vector<Constant*> GEPIdx(2, Constant::getNullValue(Type::Int32Ty));
+ AbortMessage = ConstantExpr::getGetElementPtr(MsgGV, &GEPIdx[0], 2);
+ } else {
+ // The abort message for cheap EH support tells the user that EH is not
+ // enabled.
+ Constant *Msg =
+ ConstantArray::get("Exception handler needed, but not enabled. Recompile"
+ " program with -enable-correct-eh-support.\n");
+ AbortMessageLength = Msg->getNumOperands()-1; // don't include \0
+
+ GlobalVariable *MsgGV = new GlobalVariable(Msg->getType(), true,
+ GlobalValue::InternalLinkage,
+ Msg, "abortmsg", M);
+ std::vector<Constant*> GEPIdx(2, Constant::getNullValue(Type::Int32Ty));
+ AbortMessage = ConstantExpr::getGetElementPtr(MsgGV, &GEPIdx[0], 2);
+ }
+}
+
+
+void LowerInvoke::writeAbortMessage(Instruction *IB) {
+#if 0
+ if (AbortMessage == 0)
+ createAbortMessage(IB->getParent()->getParent()->getParent());
+
+ // These are the arguments we WANT...
+ Value* Args[3];
+ Args[0] = ConstantInt::get(Type::Int32Ty, 2);
+ Args[1] = AbortMessage;
+ Args[2] = ConstantInt::get(Type::Int32Ty, AbortMessageLength);
+ (new CallInst(WriteFn, Args, 3, "", IB))->setTailCall();
+#endif
+}
+
+bool LowerInvoke::insertCheapEHSupport(Function &F) {
+ bool Changed = false;
+ for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
+ if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
+ std::vector<Value*> CallArgs(II->op_begin()+3, II->op_end());
+ // Insert a normal call instruction...
+ CallInst *NewCall = CallInst::Create(II->getCalledValue(),
+ CallArgs.begin(), CallArgs.end(), "",II);
+ NewCall->takeName(II);
+ NewCall->setCallingConv(II->getCallingConv());
+ NewCall->setAttributes(II->getAttributes());
+ II->replaceAllUsesWith(NewCall);
+
+ // Insert an unconditional branch to the normal destination.
+ BranchInst::Create(II->getNormalDest(), II);
+
+ // Remove any PHI node entries from the exception destination.
+ II->getUnwindDest()->removePredecessor(BB);
+
+ // Remove the invoke instruction now.
+ BB->getInstList().erase(II);
+
+ ++NumInvokes; Changed = true;
+ } else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) {
+ // Insert a new call to write(2, AbortMessage, AbortMessageLength);
+ writeAbortMessage(UI);
+
+ // Insert a call to abort()
+ CallInst::Create(AbortFn, "", UI)->setTailCall();
+
+ // Insert a return instruction. This really should be a "barrier", as it
+ // is unreachable.
+ ReturnInst::Create(F.getReturnType() == Type::VoidTy ? 0 :
+ Constant::getNullValue(F.getReturnType()), UI);
+
+ // Remove the unwind instruction now.
+ BB->getInstList().erase(UI);
+
+ ++NumUnwinds; Changed = true;
+ }
+ return Changed;
+}
+
+/// rewriteExpensiveInvoke - Insert code and hack the function to replace the
+/// specified invoke instruction with a call.
+void LowerInvoke::rewriteExpensiveInvoke(InvokeInst *II, unsigned InvokeNo,
+ AllocaInst *InvokeNum,
+ SwitchInst *CatchSwitch) {
+ ConstantInt *InvokeNoC = ConstantInt::get(Type::Int32Ty, InvokeNo);
+
+ // 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 a store of the invoke num before the invoke and store zero into the
+ // location afterward.
+ new StoreInst(InvokeNoC, InvokeNum, true, II); // volatile
+
+ BasicBlock::iterator NI = II->getNormalDest()->getFirstNonPHI();
+ // nonvolatile.
+ new StoreInst(Constant::getNullValue(Type::Int32Ty), InvokeNum, false, NI);
+
+ // Add a switch case to our unwind block.
+ CatchSwitch->addCase(InvokeNoC, II->getUnwindDest());
+
+ // Insert a normal call instruction.
+ std::vector<Value*> CallArgs(II->op_begin()+3, II->op_end());
+ CallInst *NewCall = CallInst::Create(II->getCalledValue(),
+ CallArgs.begin(), CallArgs.end(), "",
+ II);
+ NewCall->takeName(II);
+ NewCall->setCallingConv(II->getCallingConv());
+ NewCall->setAttributes(II->getAttributes());
+ II->replaceAllUsesWith(NewCall);
+
+ // Replace the invoke with an uncond branch.
+ BranchInst::Create(II->getNormalDest(), NewCall->getParent());
+ II->eraseFromParent();
+}
+
+/// 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);
+}
+
+// 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.
+void LowerInvoke::
+splitLiveRangesLiveAcrossInvokes(std::vector<InvokeInst*> &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) {
+ // 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<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.
+ std::vector<Instruction*> 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);
+ }
+
+ // 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<InvokeInst*> InvokesWithStoreInserted;
+
+ // 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.
+ if (NeedsSpill) {
+ ++NumSpilled;
+ DemoteRegToStack(*Inst, true);
+ }
+ }
+}
+
+bool LowerInvoke::insertExpensiveEHSupport(Function &F) {
+ std::vector<ReturnInst*> Returns;
+ std::vector<UnwindInst*> Unwinds;
+ std::vector<InvokeInst*> Invokes;
+
+ 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 (Unwinds.empty() && Invokes.empty()) return false;
+
+ NumInvokes += Invokes.size();
+ NumUnwinds += Unwinds.size();
+
+ // TODO: This is not an optimal way to do this. In particular, this always
+ // inserts setjmp calls into the entries of functions with invoke instructions
+ // even though there are possibly paths through the function that do not
+ // execute any invokes. In particular, for functions with early exits, e.g.
+ // the 'addMove' method in hexxagon, it would be nice to not have to do the
+ // setjmp stuff on the early exit path. This requires a bit of dataflow, but
+ // would not be too hard to do.
+
+ // If we have an invoke instruction, insert a setjmp that dominates all
+ // invokes. After the setjmp, use a cond branch that goes to the original
+ // code path on zero, and to a designated 'catch' block of nonzero.
+ Value *OldJmpBufPtr = 0;
+ if (!Invokes.empty()) {
+ // 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 live across invokes.
+ unsigned Align = TLI ? TLI->getJumpBufAlignment() : 0;
+ AllocaInst *JmpBuf =
+ new AllocaInst(JBLinkTy, 0, Align, "jblink", F.begin()->begin());
+
+ std::vector<Value*> Idx;
+ Idx.push_back(Constant::getNullValue(Type::Int32Ty));
+ Idx.push_back(ConstantInt::get(Type::Int32Ty, 1));
+ OldJmpBufPtr = GetElementPtrInst::Create(JmpBuf, Idx.begin(), Idx.end(),
+ "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 = BasicBlock::Create("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 = BasicBlock::Create("unwindbb", &F);
+ Unwinds.push_back(new UnwindInst(UnwindBB));
+
+ Value *CatchLoad = new LoadInst(InvokeNum, "invoke.num", true, CatchBB);
+ SwitchInst *CatchSwitch =
+ SwitchInst::Create(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 = GetElementPtrInst::Create(JmpBuf, Idx.begin(), Idx.end(),
+ "TheJmpBuf",
+ EntryBB->getTerminator());
+ JmpBufPtr = new BitCastInst(JmpBufPtr, PointerType::getUnqual(Type::Int8Ty),
+ "tmp", EntryBB->getTerminator());
+ Value *SJRet = CallInst::Create(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.
+ BranchInst::Create(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 = BasicBlock::Create("dounwind", &F);
+ BasicBlock *UnwindBlock = BasicBlock::Create("unwind", &F);
+ BasicBlock *TermBlock = BasicBlock::Create("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);
+ BranchInst::Create(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] = GetElementPtrInst::Create(BufPtr, Idx.begin(), Idx.end(), "JmpBuf",
+ UnwindBlock);
+ Idx[0] = new BitCastInst(Idx[0], PointerType::getUnqual(Type::Int8Ty),
+ "tmp", UnwindBlock);
+ Idx[1] = ConstantInt::get(Type::Int32Ty, 1);
+ CallInst::Create(LongJmpFn, Idx.begin(), Idx.end(), "", 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()
+ CallInst::Create(AbortFn, "",
+ TermBlock->getTerminator())->setTailCall();
+
+
+ // Replace all unwinds with a branch to the unwind handler.
+ for (unsigned i = 0, e = Unwinds.size(); i != e; ++i) {
+ BranchInst::Create(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);
+}
generated by cgit v1.2.3 (git 2.25.1) at 2025-11-04 11:57:52 +0000