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/Module.h"
43 #include "llvm/Pass.h"
44 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
45 #include "llvm/Transforms/Utils/Local.h"
46 #include "llvm/ADT/Statistic.h"
47 #include "llvm/Support/CommandLine.h"
48 #include "llvm/Support/Compiler.h"
49 #include "llvm/Target/TargetLowering.h"
54 STATISTIC(NumInvokes, "Number of invokes replaced");
55 STATISTIC(NumUnwinds, "Number of unwinds replaced");
56 STATISTIC(NumSpilled, "Number of registers live across unwind edges");
58 static cl::opt<bool> ExpensiveEHSupport("enable-correct-eh-support",
59 cl::desc("Make the -lowerinvoke pass insert expensive, but correct, EH code"));
62 class VISIBILITY_HIDDEN LowerInvoke : public FunctionPass {
63 // Used for both models.
67 unsigned AbortMessageLength;
69 // Used for expensive EH support.
71 GlobalVariable *JBListHead;
72 Constant *SetJmpFn, *LongJmpFn;
74 // We peek in TLI to grab the target's jmp_buf size and alignment
75 const TargetLowering *TLI;
78 static char ID; // Pass identification, replacement for typeid
79 explicit LowerInvoke(const TargetLowering *tli = NULL)
80 : FunctionPass((intptr_t)&ID), TLI(tli) { }
81 bool doInitialization(Module &M);
82 bool runOnFunction(Function &F);
84 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
85 // This is a cluster of orthogonal Transforms
86 AU.addPreservedID(PromoteMemoryToRegisterID);
87 AU.addPreservedID(LowerSelectID);
88 AU.addPreservedID(LowerSwitchID);
89 AU.addPreservedID(LowerAllocationsID);
93 void createAbortMessage(Module *M);
94 void writeAbortMessage(Instruction *IB);
95 bool insertCheapEHSupport(Function &F);
96 void splitLiveRangesLiveAcrossInvokes(std::vector<InvokeInst*> &Invokes);
97 void rewriteExpensiveInvoke(InvokeInst *II, unsigned InvokeNo,
98 AllocaInst *InvokeNum, SwitchInst *CatchSwitch);
99 bool insertExpensiveEHSupport(Function &F);
102 char LowerInvoke::ID = 0;
103 RegisterPass<LowerInvoke>
104 X("lowerinvoke", "Lower invoke and unwind, for unwindless code generators");
107 const PassInfo *llvm::LowerInvokePassID = X.getPassInfo();
109 // Public Interface To the LowerInvoke pass.
110 FunctionPass *llvm::createLowerInvokePass(const TargetLowering *TLI) {
111 return new LowerInvoke(TLI);
114 // doInitialization - Make sure that there is a prototype for abort in the
116 bool LowerInvoke::doInitialization(Module &M) {
117 const Type *VoidPtrTy = PointerType::getUnqual(Type::Int8Ty);
119 if (ExpensiveEHSupport) {
120 // Insert a type for the linked list of jump buffers.
121 unsigned JBSize = TLI ? TLI->getJumpBufSize() : 0;
122 JBSize = JBSize ? JBSize : 200;
123 const Type *JmpBufTy = ArrayType::get(VoidPtrTy, JBSize);
125 { // The type is recursive, so use a type holder.
126 std::vector<const Type*> Elements;
127 Elements.push_back(JmpBufTy);
128 OpaqueType *OT = OpaqueType::get();
129 Elements.push_back(PointerType::getUnqual(OT));
130 PATypeHolder JBLType(StructType::get(Elements));
131 OT->refineAbstractTypeTo(JBLType.get()); // Complete the cycle.
132 JBLinkTy = JBLType.get();
133 M.addTypeName("llvm.sjljeh.jmpbufty", JBLinkTy);
136 const Type *PtrJBList = PointerType::getUnqual(JBLinkTy);
138 // Now that we've done that, insert the jmpbuf list head global, unless it
140 if (!(JBListHead = M.getGlobalVariable("llvm.sjljeh.jblist", PtrJBList))) {
141 JBListHead = new GlobalVariable(PtrJBList, false,
142 GlobalValue::LinkOnceLinkage,
143 Constant::getNullValue(PtrJBList),
144 "llvm.sjljeh.jblist", &M);
146 SetJmpFn = M.getOrInsertFunction("llvm.setjmp", Type::Int32Ty,
147 PointerType::getUnqual(JmpBufTy),
149 LongJmpFn = M.getOrInsertFunction("llvm.longjmp", Type::VoidTy,
150 PointerType::getUnqual(JmpBufTy),
151 Type::Int32Ty, (Type *)0);
154 // We need the 'write' and 'abort' functions for both models.
155 AbortFn = M.getOrInsertFunction("abort", Type::VoidTy, (Type *)0);
156 #if 0 // "write" is Unix-specific.. code is going away soon anyway.
157 WriteFn = M.getOrInsertFunction("write", Type::VoidTy, Type::Int32Ty,
158 VoidPtrTy, Type::Int32Ty, (Type *)0);
165 void LowerInvoke::createAbortMessage(Module *M) {
166 if (ExpensiveEHSupport) {
167 // The abort message for expensive EH support tells the user that the
168 // program 'unwound' without an 'invoke' instruction.
170 ConstantArray::get("ERROR: Exception thrown, but not caught!\n");
171 AbortMessageLength = Msg->getNumOperands()-1; // don't include \0
173 GlobalVariable *MsgGV = new GlobalVariable(Msg->getType(), true,
174 GlobalValue::InternalLinkage,
176 std::vector<Constant*> GEPIdx(2, Constant::getNullValue(Type::Int32Ty));
177 AbortMessage = ConstantExpr::getGetElementPtr(MsgGV, &GEPIdx[0], 2);
179 // The abort message for cheap EH support tells the user that EH is not
182 ConstantArray::get("Exception handler needed, but not enabled. Recompile"
183 " program with -enable-correct-eh-support.\n");
184 AbortMessageLength = Msg->getNumOperands()-1; // don't include \0
186 GlobalVariable *MsgGV = new GlobalVariable(Msg->getType(), true,
187 GlobalValue::InternalLinkage,
189 std::vector<Constant*> GEPIdx(2, Constant::getNullValue(Type::Int32Ty));
190 AbortMessage = ConstantExpr::getGetElementPtr(MsgGV, &GEPIdx[0], 2);
195 void LowerInvoke::writeAbortMessage(Instruction *IB) {
197 if (AbortMessage == 0)
198 createAbortMessage(IB->getParent()->getParent()->getParent());
200 // These are the arguments we WANT...
202 Args[0] = ConstantInt::get(Type::Int32Ty, 2);
203 Args[1] = AbortMessage;
204 Args[2] = ConstantInt::get(Type::Int32Ty, AbortMessageLength);
205 (new CallInst(WriteFn, Args, 3, "", IB))->setTailCall();
209 bool LowerInvoke::insertCheapEHSupport(Function &F) {
210 bool Changed = false;
211 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
212 if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
213 std::vector<Value*> CallArgs(II->op_begin()+3, II->op_end());
214 // Insert a normal call instruction...
215 CallInst *NewCall = new CallInst(II->getCalledValue(),
216 CallArgs.begin(), CallArgs.end(), "",II);
217 NewCall->takeName(II);
218 NewCall->setCallingConv(II->getCallingConv());
219 NewCall->setParamAttrs(II->getParamAttrs());
220 II->replaceAllUsesWith(NewCall);
222 // Insert an unconditional branch to the normal destination.
223 new BranchInst(II->getNormalDest(), II);
225 // Remove any PHI node entries from the exception destination.
226 II->getUnwindDest()->removePredecessor(BB);
228 // Remove the invoke instruction now.
229 BB->getInstList().erase(II);
231 ++NumInvokes; Changed = true;
232 } else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) {
233 // Insert a new call to write(2, AbortMessage, AbortMessageLength);
234 writeAbortMessage(UI);
236 // Insert a call to abort()
237 (new CallInst(AbortFn, "", UI))->setTailCall();
239 // Insert a return instruction. This really should be a "barrier", as it
241 new ReturnInst(F.getReturnType() == Type::VoidTy ? 0 :
242 Constant::getNullValue(F.getReturnType()), UI);
244 // Remove the unwind instruction now.
245 BB->getInstList().erase(UI);
247 ++NumUnwinds; Changed = true;
252 /// rewriteExpensiveInvoke - Insert code and hack the function to replace the
253 /// specified invoke instruction with a call.
254 void LowerInvoke::rewriteExpensiveInvoke(InvokeInst *II, unsigned InvokeNo,
255 AllocaInst *InvokeNum,
256 SwitchInst *CatchSwitch) {
257 ConstantInt *InvokeNoC = ConstantInt::get(Type::Int32Ty, InvokeNo);
259 // If the unwind edge has phi nodes, split the edge.
260 if (isa<PHINode>(II->getUnwindDest()->begin())) {
261 SplitCriticalEdge(II, 1, this);
263 // If there are any phi nodes left, they must have a single predecessor.
264 while (PHINode *PN = dyn_cast<PHINode>(II->getUnwindDest()->begin())) {
265 PN->replaceAllUsesWith(PN->getIncomingValue(0));
266 PN->eraseFromParent();
270 // Insert a store of the invoke num before the invoke and store zero into the
271 // location afterward.
272 new StoreInst(InvokeNoC, InvokeNum, true, II); // volatile
274 BasicBlock::iterator NI = II->getNormalDest()->begin();
275 while (isa<PHINode>(NI)) ++NI;
277 new StoreInst(Constant::getNullValue(Type::Int32Ty), InvokeNum, false, NI);
279 // Add a switch case to our unwind block.
280 CatchSwitch->addCase(InvokeNoC, II->getUnwindDest());
282 // Insert a normal call instruction.
283 std::vector<Value*> CallArgs(II->op_begin()+3, II->op_end());
284 CallInst *NewCall = new CallInst(II->getCalledValue(),
285 CallArgs.begin(), CallArgs.end(), "",
287 NewCall->takeName(II);
288 NewCall->setCallingConv(II->getCallingConv());
289 NewCall->setParamAttrs(II->getParamAttrs());
290 II->replaceAllUsesWith(NewCall);
292 // Replace the invoke with an uncond branch.
293 new BranchInst(II->getNormalDest(), NewCall->getParent());
294 II->eraseFromParent();
297 /// MarkBlocksLiveIn - Insert BB and all of its predescessors into LiveBBs until
298 /// we reach blocks we've already seen.
299 static void MarkBlocksLiveIn(BasicBlock *BB, std::set<BasicBlock*> &LiveBBs) {
300 if (!LiveBBs.insert(BB).second) return; // already been here.
302 for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
303 MarkBlocksLiveIn(*PI, LiveBBs);
306 // First thing we need to do is scan the whole function for values that are
307 // live across unwind edges. Each value that is live across an unwind edge
308 // we spill into a stack location, guaranteeing that there is nothing live
309 // across the unwind edge. This process also splits all critical edges
310 // coming out of invoke's.
312 splitLiveRangesLiveAcrossInvokes(std::vector<InvokeInst*> &Invokes) {
313 // First step, split all critical edges from invoke instructions.
314 for (unsigned i = 0, e = Invokes.size(); i != e; ++i) {
315 InvokeInst *II = Invokes[i];
316 SplitCriticalEdge(II, 0, this);
317 SplitCriticalEdge(II, 1, this);
318 assert(!isa<PHINode>(II->getNormalDest()) &&
319 !isa<PHINode>(II->getUnwindDest()) &&
320 "critical edge splitting left single entry phi nodes?");
323 Function *F = Invokes.back()->getParent()->getParent();
325 // To avoid having to handle incoming arguments specially, we lower each arg
326 // to a copy instruction in the entry block. This ensures that the argument
327 // value itself cannot be live across the entry block.
328 BasicBlock::iterator AfterAllocaInsertPt = F->begin()->begin();
329 while (isa<AllocaInst>(AfterAllocaInsertPt) &&
330 isa<ConstantInt>(cast<AllocaInst>(AfterAllocaInsertPt)->getArraySize()))
331 ++AfterAllocaInsertPt;
332 for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
334 // This is always a no-op cast because we're casting AI to AI->getType() so
335 // src and destination types are identical. BitCast is the only possibility.
336 CastInst *NC = new BitCastInst(
337 AI, AI->getType(), AI->getName()+".tmp", AfterAllocaInsertPt);
338 AI->replaceAllUsesWith(NC);
339 // Normally its is forbidden to replace a CastInst's operand because it
340 // could cause the opcode to reflect an illegal conversion. However, we're
341 // replacing it here with the same value it was constructed with to simply
343 NC->setOperand(0, AI);
346 // Finally, scan the code looking for instructions with bad live ranges.
347 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
348 for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ++II) {
349 // Ignore obvious cases we don't have to handle. In particular, most
350 // instructions either have no uses or only have a single use inside the
351 // current block. Ignore them quickly.
352 Instruction *Inst = II;
353 if (Inst->use_empty()) continue;
354 if (Inst->hasOneUse() &&
355 cast<Instruction>(Inst->use_back())->getParent() == BB &&
356 !isa<PHINode>(Inst->use_back())) continue;
358 // If this is an alloca in the entry block, it's not a real register
360 if (AllocaInst *AI = dyn_cast<AllocaInst>(Inst))
361 if (isa<ConstantInt>(AI->getArraySize()) && BB == F->begin())
364 // Avoid iterator invalidation by copying users to a temporary vector.
365 std::vector<Instruction*> Users;
366 for (Value::use_iterator UI = Inst->use_begin(), E = Inst->use_end();
368 Instruction *User = cast<Instruction>(*UI);
369 if (User->getParent() != BB || isa<PHINode>(User))
370 Users.push_back(User);
373 // Scan all of the uses and see if the live range is live across an unwind
374 // edge. If we find a use live across an invoke edge, create an alloca
375 // and spill the value.
376 std::set<InvokeInst*> InvokesWithStoreInserted;
378 // Find all of the blocks that this value is live in.
379 std::set<BasicBlock*> LiveBBs;
380 LiveBBs.insert(Inst->getParent());
381 while (!Users.empty()) {
382 Instruction *U = Users.back();
385 if (!isa<PHINode>(U)) {
386 MarkBlocksLiveIn(U->getParent(), LiveBBs);
388 // Uses for a PHI node occur in their predecessor block.
389 PHINode *PN = cast<PHINode>(U);
390 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
391 if (PN->getIncomingValue(i) == Inst)
392 MarkBlocksLiveIn(PN->getIncomingBlock(i), LiveBBs);
396 // Now that we know all of the blocks that this thing is live in, see if
397 // it includes any of the unwind locations.
398 bool NeedsSpill = false;
399 for (unsigned i = 0, e = Invokes.size(); i != e; ++i) {
400 BasicBlock *UnwindBlock = Invokes[i]->getUnwindDest();
401 if (UnwindBlock != BB && LiveBBs.count(UnwindBlock)) {
406 // If we decided we need a spill, do it.
409 DemoteRegToStack(*Inst, true);
414 bool LowerInvoke::insertExpensiveEHSupport(Function &F) {
415 std::vector<ReturnInst*> Returns;
416 std::vector<UnwindInst*> Unwinds;
417 std::vector<InvokeInst*> Invokes;
419 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
420 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) {
421 // Remember all return instructions in case we insert an invoke into this
423 Returns.push_back(RI);
424 } else if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
425 Invokes.push_back(II);
426 } else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) {
427 Unwinds.push_back(UI);
430 if (Unwinds.empty() && Invokes.empty()) return false;
432 NumInvokes += Invokes.size();
433 NumUnwinds += Unwinds.size();
435 // TODO: This is not an optimal way to do this. In particular, this always
436 // inserts setjmp calls into the entries of functions with invoke instructions
437 // even though there are possibly paths through the function that do not
438 // execute any invokes. In particular, for functions with early exits, e.g.
439 // the 'addMove' method in hexxagon, it would be nice to not have to do the
440 // setjmp stuff on the early exit path. This requires a bit of dataflow, but
441 // would not be too hard to do.
443 // If we have an invoke instruction, insert a setjmp that dominates all
444 // invokes. After the setjmp, use a cond branch that goes to the original
445 // code path on zero, and to a designated 'catch' block of nonzero.
446 Value *OldJmpBufPtr = 0;
447 if (!Invokes.empty()) {
448 // First thing we need to do is scan the whole function for values that are
449 // live across unwind edges. Each value that is live across an unwind edge
450 // we spill into a stack location, guaranteeing that there is nothing live
451 // across the unwind edge. This process also splits all critical edges
452 // coming out of invoke's.
453 splitLiveRangesLiveAcrossInvokes(Invokes);
455 BasicBlock *EntryBB = F.begin();
457 // Create an alloca for the incoming jump buffer ptr and the new jump buffer
458 // that needs to be restored on all exits from the function. This is an
459 // alloca because the value needs to be live across invokes.
460 unsigned Align = TLI ? TLI->getJumpBufAlignment() : 0;
462 new AllocaInst(JBLinkTy, 0, Align, "jblink", F.begin()->begin());
464 std::vector<Value*> Idx;
465 Idx.push_back(Constant::getNullValue(Type::Int32Ty));
466 Idx.push_back(ConstantInt::get(Type::Int32Ty, 1));
467 OldJmpBufPtr = new GetElementPtrInst(JmpBuf, Idx.begin(), Idx.end(),
468 "OldBuf", EntryBB->getTerminator());
470 // Copy the JBListHead to the alloca.
471 Value *OldBuf = new LoadInst(JBListHead, "oldjmpbufptr", true,
472 EntryBB->getTerminator());
473 new StoreInst(OldBuf, OldJmpBufPtr, true, EntryBB->getTerminator());
475 // Add the new jumpbuf to the list.
476 new StoreInst(JmpBuf, JBListHead, true, EntryBB->getTerminator());
478 // Create the catch block. The catch block is basically a big switch
479 // statement that goes to all of the invoke catch blocks.
480 BasicBlock *CatchBB = new BasicBlock("setjmp.catch", &F);
482 // Create an alloca which keeps track of which invoke is currently
483 // executing. For normal calls it contains zero.
484 AllocaInst *InvokeNum = new AllocaInst(Type::Int32Ty, 0, "invokenum",
486 new StoreInst(ConstantInt::get(Type::Int32Ty, 0), InvokeNum, true,
487 EntryBB->getTerminator());
489 // Insert a load in the Catch block, and a switch on its value. By default,
490 // we go to a block that just does an unwind (which is the correct action
491 // for a standard call).
492 BasicBlock *UnwindBB = new BasicBlock("unwindbb", &F);
493 Unwinds.push_back(new UnwindInst(UnwindBB));
495 Value *CatchLoad = new LoadInst(InvokeNum, "invoke.num", true, CatchBB);
496 SwitchInst *CatchSwitch =
497 new SwitchInst(CatchLoad, UnwindBB, Invokes.size(), CatchBB);
499 // Now that things are set up, insert the setjmp call itself.
501 // Split the entry block to insert the conditional branch for the setjmp.
502 BasicBlock *ContBlock = EntryBB->splitBasicBlock(EntryBB->getTerminator(),
505 Idx[1] = ConstantInt::get(Type::Int32Ty, 0);
506 Value *JmpBufPtr = new GetElementPtrInst(JmpBuf, Idx.begin(), Idx.end(),
508 EntryBB->getTerminator());
509 Value *SJRet = new CallInst(SetJmpFn, JmpBufPtr, "sjret",
510 EntryBB->getTerminator());
512 // Compare the return value to zero.
513 Value *IsNormal = new ICmpInst(ICmpInst::ICMP_EQ, SJRet,
514 Constant::getNullValue(SJRet->getType()),
515 "notunwind", EntryBB->getTerminator());
516 // Nuke the uncond branch.
517 EntryBB->getTerminator()->eraseFromParent();
519 // Put in a new condbranch in its place.
520 new BranchInst(ContBlock, CatchBB, IsNormal, EntryBB);
522 // At this point, we are all set up, rewrite each invoke instruction.
523 for (unsigned i = 0, e = Invokes.size(); i != e; ++i)
524 rewriteExpensiveInvoke(Invokes[i], i+1, InvokeNum, CatchSwitch);
527 // We know that there is at least one unwind.
529 // Create three new blocks, the block to load the jmpbuf ptr and compare
530 // against null, the block to do the longjmp, and the error block for if it
531 // is null. Add them at the end of the function because they are not hot.
532 BasicBlock *UnwindHandler = new BasicBlock("dounwind", &F);
533 BasicBlock *UnwindBlock = new BasicBlock("unwind", &F);
534 BasicBlock *TermBlock = new BasicBlock("unwinderror", &F);
536 // If this function contains an invoke, restore the old jumpbuf ptr.
539 // Before the return, insert a copy from the saved value to the new value.
540 BufPtr = new LoadInst(OldJmpBufPtr, "oldjmpbufptr", UnwindHandler);
541 new StoreInst(BufPtr, JBListHead, UnwindHandler);
543 BufPtr = new LoadInst(JBListHead, "ehlist", UnwindHandler);
546 // Load the JBList, if it's null, then there was no catch!
547 Value *NotNull = new ICmpInst(ICmpInst::ICMP_NE, BufPtr,
548 Constant::getNullValue(BufPtr->getType()),
549 "notnull", UnwindHandler);
550 new BranchInst(UnwindBlock, TermBlock, NotNull, UnwindHandler);
552 // Create the block to do the longjmp.
553 // Get a pointer to the jmpbuf and longjmp.
554 std::vector<Value*> Idx;
555 Idx.push_back(Constant::getNullValue(Type::Int32Ty));
556 Idx.push_back(ConstantInt::get(Type::Int32Ty, 0));
557 Idx[0] = new GetElementPtrInst(BufPtr, Idx.begin(), Idx.end(), "JmpBuf",
559 Idx[1] = ConstantInt::get(Type::Int32Ty, 1);
560 new CallInst(LongJmpFn, Idx.begin(), Idx.end(), "", UnwindBlock);
561 new UnreachableInst(UnwindBlock);
563 // Set up the term block ("throw without a catch").
564 new UnreachableInst(TermBlock);
566 // Insert a new call to write(2, AbortMessage, AbortMessageLength);
567 writeAbortMessage(TermBlock->getTerminator());
569 // Insert a call to abort()
570 (new CallInst(AbortFn, "",
571 TermBlock->getTerminator()))->setTailCall();
574 // Replace all unwinds with a branch to the unwind handler.
575 for (unsigned i = 0, e = Unwinds.size(); i != e; ++i) {
576 new BranchInst(UnwindHandler, Unwinds[i]);
577 Unwinds[i]->eraseFromParent();
580 // Finally, for any returns from this function, if this function contains an
581 // invoke, restore the old jmpbuf pointer to its input value.
583 for (unsigned i = 0, e = Returns.size(); i != e; ++i) {
584 ReturnInst *R = Returns[i];
586 // Before the return, insert a copy from the saved value to the new value.
587 Value *OldBuf = new LoadInst(OldJmpBufPtr, "oldjmpbufptr", true, R);
588 new StoreInst(OldBuf, JBListHead, true, R);
595 bool LowerInvoke::runOnFunction(Function &F) {
596 if (ExpensiveEHSupport)
597 return insertExpensiveEHSupport(F);
599 return insertCheapEHSupport(F);