1 //===- LowerInvoke.cpp - Eliminate Invoke & Unwind instructions -----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This transformation is designed for use by code generators which do not yet
11 // support stack unwinding. This pass supports two models of exception handling
12 // lowering, the 'cheap' support and the 'expensive' support.
14 // 'Cheap' exception handling support gives the program the ability to execute
15 // any program which does not "throw an exception", by turning 'invoke'
16 // instructions into calls and by turning 'unwind' instructions into calls to
17 // abort(). If the program does dynamically use the unwind instruction, the
18 // program will print a message then abort.
20 // 'Expensive' exception handling support gives the full exception handling
21 // support to the program at the cost of making the 'invoke' instruction
22 // really expensive. It basically inserts setjmp/longjmp calls to emulate the
23 // exception handling as necessary.
25 // Because the 'expensive' support slows down programs a lot, and EH is only
26 // used for a subset of the programs, it must be specifically enabled by an
29 // Note that after this pass runs the CFG is not entirely accurate (exceptional
30 // control flow edges are not correct anymore) so only very simple things should
31 // be done after the lowerinvoke pass has run (like generation of native code).
32 // This should not be used as a general purpose "my LLVM-to-LLVM pass doesn't
33 // support the invoke instruction yet" lowering pass.
35 //===----------------------------------------------------------------------===//
37 #define DEBUG_TYPE "lowerinvoke"
38 #include "llvm/Transforms/Scalar.h"
39 #include "llvm/Constants.h"
40 #include "llvm/DerivedTypes.h"
41 #include "llvm/Instructions.h"
42 #include "llvm/Intrinsics.h"
43 #include "llvm/LLVMContext.h"
44 #include "llvm/Module.h"
45 #include "llvm/Pass.h"
46 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
47 #include "llvm/Transforms/Utils/Local.h"
48 #include "llvm/ADT/Statistic.h"
49 #include "llvm/Support/CommandLine.h"
50 #include "llvm/Support/Compiler.h"
51 #include "llvm/Target/TargetLowering.h"
56 STATISTIC(NumInvokes, "Number of invokes replaced");
57 STATISTIC(NumUnwinds, "Number of unwinds replaced");
58 STATISTIC(NumSpilled, "Number of registers live across unwind edges");
60 static cl::opt<bool> ExpensiveEHSupport("enable-correct-eh-support",
61 cl::desc("Make the -lowerinvoke pass insert expensive, but correct, EH code"));
64 class VISIBILITY_HIDDEN LowerInvoke : public FunctionPass {
65 // Used for both models.
69 unsigned AbortMessageLength;
71 // Used for expensive EH support.
73 GlobalVariable *JBListHead;
74 Constant *SetJmpFn, *LongJmpFn;
76 // We peek in TLI to grab the target's jmp_buf size and alignment
77 const TargetLowering *TLI;
80 static char ID; // Pass identification, replacement for typeid
81 explicit LowerInvoke(const TargetLowering *tli = NULL)
82 : FunctionPass(&ID), TLI(tli) { }
83 bool doInitialization(Module &M);
84 bool runOnFunction(Function &F);
86 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
87 // This is a cluster of orthogonal Transforms
88 AU.addPreservedID(PromoteMemoryToRegisterID);
89 AU.addPreservedID(LowerSwitchID);
90 AU.addPreservedID(LowerAllocationsID);
94 void createAbortMessage(Module *M);
95 void writeAbortMessage(Instruction *IB);
96 bool insertCheapEHSupport(Function &F);
97 void splitLiveRangesLiveAcrossInvokes(std::vector<InvokeInst*> &Invokes);
98 void rewriteExpensiveInvoke(InvokeInst *II, unsigned InvokeNo,
99 AllocaInst *InvokeNum, SwitchInst *CatchSwitch);
100 bool insertExpensiveEHSupport(Function &F);
104 char LowerInvoke::ID = 0;
105 static RegisterPass<LowerInvoke>
106 X("lowerinvoke", "Lower invoke and unwind, for unwindless code generators");
108 const PassInfo *const llvm::LowerInvokePassID = &X;
110 // Public Interface To the LowerInvoke pass.
111 FunctionPass *llvm::createLowerInvokePass(const TargetLowering *TLI) {
112 return new LowerInvoke(TLI);
115 // doInitialization - Make sure that there is a prototype for abort in the
117 bool LowerInvoke::doInitialization(Module &M) {
118 LLVMContext &Context = M.getContext();
120 const Type *VoidPtrTy = Context.getPointerTypeUnqual(Type::Int8Ty);
122 if (ExpensiveEHSupport) {
123 // Insert a type for the linked list of jump buffers.
124 unsigned JBSize = TLI ? TLI->getJumpBufSize() : 0;
125 JBSize = JBSize ? JBSize : 200;
126 const Type *JmpBufTy = Context.getArrayType(VoidPtrTy, JBSize);
128 { // The type is recursive, so use a type holder.
129 std::vector<const Type*> Elements;
130 Elements.push_back(JmpBufTy);
131 OpaqueType *OT = Context.getOpaqueType();
132 Elements.push_back(Context.getPointerTypeUnqual(OT));
133 PATypeHolder JBLType(Context.getStructType(Elements));
134 OT->refineAbstractTypeTo(JBLType.get()); // Complete the cycle.
135 JBLinkTy = JBLType.get();
136 M.addTypeName("llvm.sjljeh.jmpbufty", JBLinkTy);
139 const Type *PtrJBList = Context.getPointerTypeUnqual(JBLinkTy);
141 // Now that we've done that, insert the jmpbuf list head global, unless it
143 if (!(JBListHead = M.getGlobalVariable("llvm.sjljeh.jblist", PtrJBList))) {
144 JBListHead = new GlobalVariable(M, PtrJBList, false,
145 GlobalValue::LinkOnceAnyLinkage,
146 Context.getNullValue(PtrJBList),
147 "llvm.sjljeh.jblist");
150 // VisualStudio defines setjmp as _setjmp via #include <csetjmp> / <setjmp.h>,
151 // so it looks like Intrinsic::_setjmp
152 #if defined(_MSC_VER) && defined(setjmp)
153 #define setjmp_undefined_for_visual_studio
157 SetJmpFn = Intrinsic::getDeclaration(&M, Intrinsic::setjmp);
159 #if defined(_MSC_VER) && defined(setjmp_undefined_for_visual_studio)
160 // let's return it to _setjmp state in case anyone ever needs it after this
161 // point under VisualStudio
162 #define setjmp _setjmp
165 LongJmpFn = Intrinsic::getDeclaration(&M, Intrinsic::longjmp);
168 // We need the 'write' and 'abort' functions for both models.
169 AbortFn = M.getOrInsertFunction("abort", Type::VoidTy, (Type *)0);
170 #if 0 // "write" is Unix-specific.. code is going away soon anyway.
171 WriteFn = M.getOrInsertFunction("write", Type::VoidTy, Type::Int32Ty,
172 VoidPtrTy, Type::Int32Ty, (Type *)0);
179 void LowerInvoke::createAbortMessage(Module *M) {
180 LLVMContext &Context = M->getContext();
182 if (ExpensiveEHSupport) {
183 // The abort message for expensive EH support tells the user that the
184 // program 'unwound' without an 'invoke' instruction.
186 Context.getConstantArray("ERROR: Exception thrown, but not caught!\n");
187 AbortMessageLength = Msg->getNumOperands()-1; // don't include \0
189 GlobalVariable *MsgGV = new GlobalVariable(*M, Msg->getType(), true,
190 GlobalValue::InternalLinkage,
192 std::vector<Constant*> GEPIdx(2, Context.getNullValue(Type::Int32Ty));
193 AbortMessage = Context.getConstantExprGetElementPtr(MsgGV, &GEPIdx[0], 2);
195 // The abort message for cheap EH support tells the user that EH is not
198 Context.getConstantArray("Exception handler needed, but not enabled."
199 "Recompile program with -enable-correct-eh-support.\n");
200 AbortMessageLength = Msg->getNumOperands()-1; // don't include \0
202 GlobalVariable *MsgGV = new GlobalVariable(*M, Msg->getType(), true,
203 GlobalValue::InternalLinkage,
205 std::vector<Constant*> GEPIdx(2, Context.getNullValue(Type::Int32Ty));
206 AbortMessage = ConstantExpr::getGetElementPtr(MsgGV, &GEPIdx[0], 2);
211 void LowerInvoke::writeAbortMessage(Instruction *IB) {
213 if (AbortMessage == 0)
214 createAbortMessage(IB->getParent()->getParent()->getParent());
216 // These are the arguments we WANT...
218 Args[0] = ConstantInt::get(Type::Int32Ty, 2);
219 Args[1] = AbortMessage;
220 Args[2] = ConstantInt::get(Type::Int32Ty, AbortMessageLength);
221 (new CallInst(WriteFn, Args, 3, "", IB))->setTailCall();
225 bool LowerInvoke::insertCheapEHSupport(Function &F) {
226 LLVMContext &Context = F.getContext();
227 bool Changed = false;
228 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
229 if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
230 std::vector<Value*> CallArgs(II->op_begin()+3, II->op_end());
231 // Insert a normal call instruction...
232 CallInst *NewCall = CallInst::Create(II->getCalledValue(),
233 CallArgs.begin(), CallArgs.end(), "",II);
234 NewCall->takeName(II);
235 NewCall->setCallingConv(II->getCallingConv());
236 NewCall->setAttributes(II->getAttributes());
237 II->replaceAllUsesWith(NewCall);
239 // Insert an unconditional branch to the normal destination.
240 BranchInst::Create(II->getNormalDest(), II);
242 // Remove any PHI node entries from the exception destination.
243 II->getUnwindDest()->removePredecessor(BB);
245 // Remove the invoke instruction now.
246 BB->getInstList().erase(II);
248 ++NumInvokes; Changed = true;
249 } else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) {
250 // Insert a new call to write(2, AbortMessage, AbortMessageLength);
251 writeAbortMessage(UI);
253 // Insert a call to abort()
254 CallInst::Create(AbortFn, "", UI)->setTailCall();
256 // Insert a return instruction. This really should be a "barrier", as it
258 ReturnInst::Create(F.getReturnType() == Type::VoidTy ? 0 :
259 Context.getNullValue(F.getReturnType()), UI);
261 // Remove the unwind instruction now.
262 BB->getInstList().erase(UI);
264 ++NumUnwinds; Changed = true;
269 /// rewriteExpensiveInvoke - Insert code and hack the function to replace the
270 /// specified invoke instruction with a call.
271 void LowerInvoke::rewriteExpensiveInvoke(InvokeInst *II, unsigned InvokeNo,
272 AllocaInst *InvokeNum,
273 SwitchInst *CatchSwitch) {
274 LLVMContext &Context = II->getContext();
275 ConstantInt *InvokeNoC = ConstantInt::get(Type::Int32Ty, InvokeNo);
277 // If the unwind edge has phi nodes, split the edge.
278 if (isa<PHINode>(II->getUnwindDest()->begin())) {
279 SplitCriticalEdge(II, 1, this);
281 // If there are any phi nodes left, they must have a single predecessor.
282 while (PHINode *PN = dyn_cast<PHINode>(II->getUnwindDest()->begin())) {
283 PN->replaceAllUsesWith(PN->getIncomingValue(0));
284 PN->eraseFromParent();
288 // Insert a store of the invoke num before the invoke and store zero into the
289 // location afterward.
290 new StoreInst(InvokeNoC, InvokeNum, true, II); // volatile
292 BasicBlock::iterator NI = II->getNormalDest()->getFirstNonPHI();
294 new StoreInst(Context.getNullValue(Type::Int32Ty), InvokeNum, false, NI);
296 // Add a switch case to our unwind block.
297 CatchSwitch->addCase(InvokeNoC, II->getUnwindDest());
299 // Insert a normal call instruction.
300 std::vector<Value*> CallArgs(II->op_begin()+3, II->op_end());
301 CallInst *NewCall = CallInst::Create(II->getCalledValue(),
302 CallArgs.begin(), CallArgs.end(), "",
304 NewCall->takeName(II);
305 NewCall->setCallingConv(II->getCallingConv());
306 NewCall->setAttributes(II->getAttributes());
307 II->replaceAllUsesWith(NewCall);
309 // Replace the invoke with an uncond branch.
310 BranchInst::Create(II->getNormalDest(), NewCall->getParent());
311 II->eraseFromParent();
314 /// MarkBlocksLiveIn - Insert BB and all of its predescessors into LiveBBs until
315 /// we reach blocks we've already seen.
316 static void MarkBlocksLiveIn(BasicBlock *BB, std::set<BasicBlock*> &LiveBBs) {
317 if (!LiveBBs.insert(BB).second) return; // already been here.
319 for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
320 MarkBlocksLiveIn(*PI, LiveBBs);
323 // First thing we need to do is scan the whole function for values that are
324 // live across unwind edges. Each value that is live across an unwind edge
325 // we spill into a stack location, guaranteeing that there is nothing live
326 // across the unwind edge. This process also splits all critical edges
327 // coming out of invoke's.
329 splitLiveRangesLiveAcrossInvokes(std::vector<InvokeInst*> &Invokes) {
330 // First step, split all critical edges from invoke instructions.
331 for (unsigned i = 0, e = Invokes.size(); i != e; ++i) {
332 InvokeInst *II = Invokes[i];
333 SplitCriticalEdge(II, 0, this);
334 SplitCriticalEdge(II, 1, this);
335 assert(!isa<PHINode>(II->getNormalDest()) &&
336 !isa<PHINode>(II->getUnwindDest()) &&
337 "critical edge splitting left single entry phi nodes?");
340 Function *F = Invokes.back()->getParent()->getParent();
342 // To avoid having to handle incoming arguments specially, we lower each arg
343 // to a copy instruction in the entry block. This ensures that the argument
344 // value itself cannot be live across the entry block.
345 BasicBlock::iterator AfterAllocaInsertPt = F->begin()->begin();
346 while (isa<AllocaInst>(AfterAllocaInsertPt) &&
347 isa<ConstantInt>(cast<AllocaInst>(AfterAllocaInsertPt)->getArraySize()))
348 ++AfterAllocaInsertPt;
349 for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
351 // This is always a no-op cast because we're casting AI to AI->getType() so
352 // src and destination types are identical. BitCast is the only possibility.
353 CastInst *NC = new BitCastInst(
354 AI, AI->getType(), AI->getName()+".tmp", AfterAllocaInsertPt);
355 AI->replaceAllUsesWith(NC);
356 // Normally its is forbidden to replace a CastInst's operand because it
357 // could cause the opcode to reflect an illegal conversion. However, we're
358 // replacing it here with the same value it was constructed with to simply
360 NC->setOperand(0, AI);
363 // Finally, scan the code looking for instructions with bad live ranges.
364 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
365 for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ++II) {
366 // Ignore obvious cases we don't have to handle. In particular, most
367 // instructions either have no uses or only have a single use inside the
368 // current block. Ignore them quickly.
369 Instruction *Inst = II;
370 if (Inst->use_empty()) continue;
371 if (Inst->hasOneUse() &&
372 cast<Instruction>(Inst->use_back())->getParent() == BB &&
373 !isa<PHINode>(Inst->use_back())) continue;
375 // If this is an alloca in the entry block, it's not a real register
377 if (AllocaInst *AI = dyn_cast<AllocaInst>(Inst))
378 if (isa<ConstantInt>(AI->getArraySize()) && BB == F->begin())
381 // Avoid iterator invalidation by copying users to a temporary vector.
382 std::vector<Instruction*> Users;
383 for (Value::use_iterator UI = Inst->use_begin(), E = Inst->use_end();
385 Instruction *User = cast<Instruction>(*UI);
386 if (User->getParent() != BB || isa<PHINode>(User))
387 Users.push_back(User);
390 // Scan all of the uses and see if the live range is live across an unwind
391 // edge. If we find a use live across an invoke edge, create an alloca
392 // and spill the value.
393 std::set<InvokeInst*> InvokesWithStoreInserted;
395 // Find all of the blocks that this value is live in.
396 std::set<BasicBlock*> LiveBBs;
397 LiveBBs.insert(Inst->getParent());
398 while (!Users.empty()) {
399 Instruction *U = Users.back();
402 if (!isa<PHINode>(U)) {
403 MarkBlocksLiveIn(U->getParent(), LiveBBs);
405 // Uses for a PHI node occur in their predecessor block.
406 PHINode *PN = cast<PHINode>(U);
407 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
408 if (PN->getIncomingValue(i) == Inst)
409 MarkBlocksLiveIn(PN->getIncomingBlock(i), LiveBBs);
413 // Now that we know all of the blocks that this thing is live in, see if
414 // it includes any of the unwind locations.
415 bool NeedsSpill = false;
416 for (unsigned i = 0, e = Invokes.size(); i != e; ++i) {
417 BasicBlock *UnwindBlock = Invokes[i]->getUnwindDest();
418 if (UnwindBlock != BB && LiveBBs.count(UnwindBlock)) {
423 // If we decided we need a spill, do it.
426 DemoteRegToStack(*Inst, true);
431 bool LowerInvoke::insertExpensiveEHSupport(Function &F) {
432 std::vector<ReturnInst*> Returns;
433 std::vector<UnwindInst*> Unwinds;
434 std::vector<InvokeInst*> Invokes;
436 LLVMContext &Context = F.getContext();
438 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
439 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) {
440 // Remember all return instructions in case we insert an invoke into this
442 Returns.push_back(RI);
443 } else if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
444 Invokes.push_back(II);
445 } else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) {
446 Unwinds.push_back(UI);
449 if (Unwinds.empty() && Invokes.empty()) return false;
451 NumInvokes += Invokes.size();
452 NumUnwinds += Unwinds.size();
454 // TODO: This is not an optimal way to do this. In particular, this always
455 // inserts setjmp calls into the entries of functions with invoke instructions
456 // even though there are possibly paths through the function that do not
457 // execute any invokes. In particular, for functions with early exits, e.g.
458 // the 'addMove' method in hexxagon, it would be nice to not have to do the
459 // setjmp stuff on the early exit path. This requires a bit of dataflow, but
460 // would not be too hard to do.
462 // If we have an invoke instruction, insert a setjmp that dominates all
463 // invokes. After the setjmp, use a cond branch that goes to the original
464 // code path on zero, and to a designated 'catch' block of nonzero.
465 Value *OldJmpBufPtr = 0;
466 if (!Invokes.empty()) {
467 // First thing we need to do is scan the whole function for values that are
468 // live across unwind edges. Each value that is live across an unwind edge
469 // we spill into a stack location, guaranteeing that there is nothing live
470 // across the unwind edge. This process also splits all critical edges
471 // coming out of invoke's.
472 splitLiveRangesLiveAcrossInvokes(Invokes);
474 BasicBlock *EntryBB = F.begin();
476 // Create an alloca for the incoming jump buffer ptr and the new jump buffer
477 // that needs to be restored on all exits from the function. This is an
478 // alloca because the value needs to be live across invokes.
479 unsigned Align = TLI ? TLI->getJumpBufAlignment() : 0;
481 new AllocaInst(JBLinkTy, 0, Align,
482 "jblink", F.begin()->begin());
484 std::vector<Value*> Idx;
485 Idx.push_back(Context.getNullValue(Type::Int32Ty));
486 Idx.push_back(ConstantInt::get(Type::Int32Ty, 1));
487 OldJmpBufPtr = GetElementPtrInst::Create(JmpBuf, Idx.begin(), Idx.end(),
489 EntryBB->getTerminator());
491 // Copy the JBListHead to the alloca.
492 Value *OldBuf = new LoadInst(JBListHead, "oldjmpbufptr", true,
493 EntryBB->getTerminator());
494 new StoreInst(OldBuf, OldJmpBufPtr, true, EntryBB->getTerminator());
496 // Add the new jumpbuf to the list.
497 new StoreInst(JmpBuf, JBListHead, true, EntryBB->getTerminator());
499 // Create the catch block. The catch block is basically a big switch
500 // statement that goes to all of the invoke catch blocks.
501 BasicBlock *CatchBB = BasicBlock::Create("setjmp.catch", &F);
503 // Create an alloca which keeps track of which invoke is currently
504 // executing. For normal calls it contains zero.
505 AllocaInst *InvokeNum = new AllocaInst(Type::Int32Ty, 0,
506 "invokenum",EntryBB->begin());
507 new StoreInst(ConstantInt::get(Type::Int32Ty, 0), InvokeNum, true,
508 EntryBB->getTerminator());
510 // Insert a load in the Catch block, and a switch on its value. By default,
511 // we go to a block that just does an unwind (which is the correct action
512 // for a standard call).
513 BasicBlock *UnwindBB = BasicBlock::Create("unwindbb", &F);
514 Unwinds.push_back(new UnwindInst(UnwindBB));
516 Value *CatchLoad = new LoadInst(InvokeNum, "invoke.num", true, CatchBB);
517 SwitchInst *CatchSwitch =
518 SwitchInst::Create(CatchLoad, UnwindBB, Invokes.size(), CatchBB);
520 // Now that things are set up, insert the setjmp call itself.
522 // Split the entry block to insert the conditional branch for the setjmp.
523 BasicBlock *ContBlock = EntryBB->splitBasicBlock(EntryBB->getTerminator(),
526 Idx[1] = ConstantInt::get(Type::Int32Ty, 0);
527 Value *JmpBufPtr = GetElementPtrInst::Create(JmpBuf, Idx.begin(), Idx.end(),
529 EntryBB->getTerminator());
530 JmpBufPtr = new BitCastInst(JmpBufPtr, PointerType::getUnqual(Type::Int8Ty),
531 "tmp", EntryBB->getTerminator());
532 Value *SJRet = CallInst::Create(SetJmpFn, JmpBufPtr, "sjret",
533 EntryBB->getTerminator());
535 // Compare the return value to zero.
536 Value *IsNormal = new ICmpInst(EntryBB->getTerminator(),
537 ICmpInst::ICMP_EQ, SJRet,
538 Context.getNullValue(SJRet->getType()),
540 // Nuke the uncond branch.
541 EntryBB->getTerminator()->eraseFromParent();
543 // Put in a new condbranch in its place.
544 BranchInst::Create(ContBlock, CatchBB, IsNormal, EntryBB);
546 // At this point, we are all set up, rewrite each invoke instruction.
547 for (unsigned i = 0, e = Invokes.size(); i != e; ++i)
548 rewriteExpensiveInvoke(Invokes[i], i+1, InvokeNum, CatchSwitch);
551 // We know that there is at least one unwind.
553 // Create three new blocks, the block to load the jmpbuf ptr and compare
554 // against null, the block to do the longjmp, and the error block for if it
555 // is null. Add them at the end of the function because they are not hot.
556 BasicBlock *UnwindHandler = BasicBlock::Create("dounwind", &F);
557 BasicBlock *UnwindBlock = BasicBlock::Create("unwind", &F);
558 BasicBlock *TermBlock = BasicBlock::Create("unwinderror", &F);
560 // If this function contains an invoke, restore the old jumpbuf ptr.
563 // Before the return, insert a copy from the saved value to the new value.
564 BufPtr = new LoadInst(OldJmpBufPtr, "oldjmpbufptr", UnwindHandler);
565 new StoreInst(BufPtr, JBListHead, UnwindHandler);
567 BufPtr = new LoadInst(JBListHead, "ehlist", UnwindHandler);
570 // Load the JBList, if it's null, then there was no catch!
571 Value *NotNull = new ICmpInst(*UnwindHandler, ICmpInst::ICMP_NE, BufPtr,
572 Context.getNullValue(BufPtr->getType()),
574 BranchInst::Create(UnwindBlock, TermBlock, NotNull, UnwindHandler);
576 // Create the block to do the longjmp.
577 // Get a pointer to the jmpbuf and longjmp.
578 std::vector<Value*> Idx;
579 Idx.push_back(Context.getNullValue(Type::Int32Ty));
580 Idx.push_back(ConstantInt::get(Type::Int32Ty, 0));
581 Idx[0] = GetElementPtrInst::Create(BufPtr, Idx.begin(), Idx.end(), "JmpBuf",
583 Idx[0] = new BitCastInst(Idx[0], PointerType::getUnqual(Type::Int8Ty),
585 Idx[1] = ConstantInt::get(Type::Int32Ty, 1);
586 CallInst::Create(LongJmpFn, Idx.begin(), Idx.end(), "", UnwindBlock);
587 new UnreachableInst(UnwindBlock);
589 // Set up the term block ("throw without a catch").
590 new UnreachableInst(TermBlock);
592 // Insert a new call to write(2, AbortMessage, AbortMessageLength);
593 writeAbortMessage(TermBlock->getTerminator());
595 // Insert a call to abort()
596 CallInst::Create(AbortFn, "",
597 TermBlock->getTerminator())->setTailCall();
600 // Replace all unwinds with a branch to the unwind handler.
601 for (unsigned i = 0, e = Unwinds.size(); i != e; ++i) {
602 BranchInst::Create(UnwindHandler, Unwinds[i]);
603 Unwinds[i]->eraseFromParent();
606 // Finally, for any returns from this function, if this function contains an
607 // invoke, restore the old jmpbuf pointer to its input value.
609 for (unsigned i = 0, e = Returns.size(); i != e; ++i) {
610 ReturnInst *R = Returns[i];
612 // Before the return, insert a copy from the saved value to the new value.
613 Value *OldBuf = new LoadInst(OldJmpBufPtr, "oldjmpbufptr", true, R);
614 new StoreInst(OldBuf, JBListHead, true, R);
621 bool LowerInvoke::runOnFunction(Function &F) {
622 if (ExpensiveEHSupport)
623 return insertExpensiveEHSupport(F);
625 return insertCheapEHSupport(F);