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/Module.h"
44 #include "llvm/Pass.h"
45 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
46 #include "llvm/Transforms/Utils/Local.h"
47 #include "llvm/ADT/Statistic.h"
48 #include "llvm/Support/CommandLine.h"
49 #include "llvm/Support/Compiler.h"
50 #include "llvm/Target/TargetLowering.h"
55 STATISTIC(NumInvokes, "Number of invokes replaced");
56 STATISTIC(NumUnwinds, "Number of unwinds replaced");
57 STATISTIC(NumSpilled, "Number of registers live across unwind edges");
59 static cl::opt<bool> ExpensiveEHSupport("enable-correct-eh-support",
60 cl::desc("Make the -lowerinvoke pass insert expensive, but correct, EH code"));
63 class VISIBILITY_HIDDEN LowerInvoke : public FunctionPass {
64 // Used for both models.
68 unsigned AbortMessageLength;
70 // Used for expensive EH support.
72 GlobalVariable *JBListHead;
73 Constant *SetJmpFn, *LongJmpFn;
75 // We peek in TLI to grab the target's jmp_buf size and alignment
76 const TargetLowering *TLI;
79 static char ID; // Pass identification, replacement for typeid
80 explicit LowerInvoke(const TargetLowering *tli = NULL)
81 : FunctionPass((intptr_t)&ID), TLI(tli) { }
82 bool doInitialization(Module &M);
83 bool runOnFunction(Function &F);
85 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
86 // This is a cluster of orthogonal Transforms
87 AU.addPreservedID(PromoteMemoryToRegisterID);
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);
103 char LowerInvoke::ID = 0;
104 static RegisterPass<LowerInvoke>
105 X("lowerinvoke", "Lower invoke and unwind, for unwindless code generators");
107 const PassInfo *const llvm::LowerInvokePassID = &X;
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);
147 // VisualStudio defines setjmp as _setjmp via #include <csetjmp> / <setjmp.h>,
148 // so it looks like Intrinsic::_setjmp
149 #if defined(_MSC_VER) && defined(setjmp)
150 #define setjmp_undefined_for_visual_studio
154 SetJmpFn = Intrinsic::getDeclaration(&M, Intrinsic::setjmp);
156 #if defined(_MSC_VER) && defined(setjmp_undefined_for_visual_studio)
157 // let's return it to _setjmp state in case anyone ever needs it after this
158 // point under VisualStudio
159 #define setjmp _setjmp
162 LongJmpFn = Intrinsic::getDeclaration(&M, Intrinsic::longjmp);
165 // We need the 'write' and 'abort' functions for both models.
166 AbortFn = M.getOrInsertFunction("abort", Type::VoidTy, (Type *)0);
167 #if 0 // "write" is Unix-specific.. code is going away soon anyway.
168 WriteFn = M.getOrInsertFunction("write", Type::VoidTy, Type::Int32Ty,
169 VoidPtrTy, Type::Int32Ty, (Type *)0);
176 void LowerInvoke::createAbortMessage(Module *M) {
177 if (ExpensiveEHSupport) {
178 // The abort message for expensive EH support tells the user that the
179 // program 'unwound' without an 'invoke' instruction.
181 ConstantArray::get("ERROR: Exception thrown, but not caught!\n");
182 AbortMessageLength = Msg->getNumOperands()-1; // don't include \0
184 GlobalVariable *MsgGV = new GlobalVariable(Msg->getType(), true,
185 GlobalValue::InternalLinkage,
187 std::vector<Constant*> GEPIdx(2, Constant::getNullValue(Type::Int32Ty));
188 AbortMessage = ConstantExpr::getGetElementPtr(MsgGV, &GEPIdx[0], 2);
190 // The abort message for cheap EH support tells the user that EH is not
193 ConstantArray::get("Exception handler needed, but not enabled. Recompile"
194 " program with -enable-correct-eh-support.\n");
195 AbortMessageLength = Msg->getNumOperands()-1; // don't include \0
197 GlobalVariable *MsgGV = new GlobalVariable(Msg->getType(), true,
198 GlobalValue::InternalLinkage,
200 std::vector<Constant*> GEPIdx(2, Constant::getNullValue(Type::Int32Ty));
201 AbortMessage = ConstantExpr::getGetElementPtr(MsgGV, &GEPIdx[0], 2);
206 void LowerInvoke::writeAbortMessage(Instruction *IB) {
208 if (AbortMessage == 0)
209 createAbortMessage(IB->getParent()->getParent()->getParent());
211 // These are the arguments we WANT...
213 Args[0] = ConstantInt::get(Type::Int32Ty, 2);
214 Args[1] = AbortMessage;
215 Args[2] = ConstantInt::get(Type::Int32Ty, AbortMessageLength);
216 (new CallInst(WriteFn, Args, 3, "", IB))->setTailCall();
220 bool LowerInvoke::insertCheapEHSupport(Function &F) {
221 bool Changed = false;
222 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
223 if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
224 std::vector<Value*> CallArgs(II->op_begin()+3, II->op_end());
225 // Insert a normal call instruction...
226 CallInst *NewCall = CallInst::Create(II->getCalledValue(),
227 CallArgs.begin(), CallArgs.end(), "",II);
228 NewCall->takeName(II);
229 NewCall->setCallingConv(II->getCallingConv());
230 NewCall->setParamAttrs(II->getParamAttrs());
231 II->replaceAllUsesWith(NewCall);
233 // Insert an unconditional branch to the normal destination.
234 BranchInst::Create(II->getNormalDest(), II);
236 // Remove any PHI node entries from the exception destination.
237 II->getUnwindDest()->removePredecessor(BB);
239 // Remove the invoke instruction now.
240 BB->getInstList().erase(II);
242 ++NumInvokes; Changed = true;
243 } else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) {
244 // Insert a new call to write(2, AbortMessage, AbortMessageLength);
245 writeAbortMessage(UI);
247 // Insert a call to abort()
248 CallInst::Create(AbortFn, "", UI)->setTailCall();
250 // Insert a return instruction. This really should be a "barrier", as it
252 ReturnInst::Create(F.getReturnType() == Type::VoidTy ? 0 :
253 Constant::getNullValue(F.getReturnType()), UI);
255 // Remove the unwind instruction now.
256 BB->getInstList().erase(UI);
258 ++NumUnwinds; Changed = true;
263 /// rewriteExpensiveInvoke - Insert code and hack the function to replace the
264 /// specified invoke instruction with a call.
265 void LowerInvoke::rewriteExpensiveInvoke(InvokeInst *II, unsigned InvokeNo,
266 AllocaInst *InvokeNum,
267 SwitchInst *CatchSwitch) {
268 ConstantInt *InvokeNoC = ConstantInt::get(Type::Int32Ty, InvokeNo);
270 // If the unwind edge has phi nodes, split the edge.
271 if (isa<PHINode>(II->getUnwindDest()->begin())) {
272 SplitCriticalEdge(II, 1, this);
274 // If there are any phi nodes left, they must have a single predecessor.
275 while (PHINode *PN = dyn_cast<PHINode>(II->getUnwindDest()->begin())) {
276 PN->replaceAllUsesWith(PN->getIncomingValue(0));
277 PN->eraseFromParent();
281 // Insert a store of the invoke num before the invoke and store zero into the
282 // location afterward.
283 new StoreInst(InvokeNoC, InvokeNum, true, II); // volatile
285 BasicBlock::iterator NI = II->getNormalDest()->begin();
286 while (isa<PHINode>(NI)) ++NI;
288 new StoreInst(Constant::getNullValue(Type::Int32Ty), InvokeNum, false, NI);
290 // Add a switch case to our unwind block.
291 CatchSwitch->addCase(InvokeNoC, II->getUnwindDest());
293 // Insert a normal call instruction.
294 std::vector<Value*> CallArgs(II->op_begin()+3, II->op_end());
295 CallInst *NewCall = CallInst::Create(II->getCalledValue(),
296 CallArgs.begin(), CallArgs.end(), "",
298 NewCall->takeName(II);
299 NewCall->setCallingConv(II->getCallingConv());
300 NewCall->setParamAttrs(II->getParamAttrs());
301 II->replaceAllUsesWith(NewCall);
303 // Replace the invoke with an uncond branch.
304 BranchInst::Create(II->getNormalDest(), NewCall->getParent());
305 II->eraseFromParent();
308 /// MarkBlocksLiveIn - Insert BB and all of its predescessors into LiveBBs until
309 /// we reach blocks we've already seen.
310 static void MarkBlocksLiveIn(BasicBlock *BB, std::set<BasicBlock*> &LiveBBs) {
311 if (!LiveBBs.insert(BB).second) return; // already been here.
313 for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
314 MarkBlocksLiveIn(*PI, LiveBBs);
317 // First thing we need to do is scan the whole function for values that are
318 // live across unwind edges. Each value that is live across an unwind edge
319 // we spill into a stack location, guaranteeing that there is nothing live
320 // across the unwind edge. This process also splits all critical edges
321 // coming out of invoke's.
323 splitLiveRangesLiveAcrossInvokes(std::vector<InvokeInst*> &Invokes) {
324 // First step, split all critical edges from invoke instructions.
325 for (unsigned i = 0, e = Invokes.size(); i != e; ++i) {
326 InvokeInst *II = Invokes[i];
327 SplitCriticalEdge(II, 0, this);
328 SplitCriticalEdge(II, 1, this);
329 assert(!isa<PHINode>(II->getNormalDest()) &&
330 !isa<PHINode>(II->getUnwindDest()) &&
331 "critical edge splitting left single entry phi nodes?");
334 Function *F = Invokes.back()->getParent()->getParent();
336 // To avoid having to handle incoming arguments specially, we lower each arg
337 // to a copy instruction in the entry block. This ensures that the argument
338 // value itself cannot be live across the entry block.
339 BasicBlock::iterator AfterAllocaInsertPt = F->begin()->begin();
340 while (isa<AllocaInst>(AfterAllocaInsertPt) &&
341 isa<ConstantInt>(cast<AllocaInst>(AfterAllocaInsertPt)->getArraySize()))
342 ++AfterAllocaInsertPt;
343 for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
345 // This is always a no-op cast because we're casting AI to AI->getType() so
346 // src and destination types are identical. BitCast is the only possibility.
347 CastInst *NC = new BitCastInst(
348 AI, AI->getType(), AI->getName()+".tmp", AfterAllocaInsertPt);
349 AI->replaceAllUsesWith(NC);
350 // Normally its is forbidden to replace a CastInst's operand because it
351 // could cause the opcode to reflect an illegal conversion. However, we're
352 // replacing it here with the same value it was constructed with to simply
354 NC->setOperand(0, AI);
357 // Finally, scan the code looking for instructions with bad live ranges.
358 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
359 for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ++II) {
360 // Ignore obvious cases we don't have to handle. In particular, most
361 // instructions either have no uses or only have a single use inside the
362 // current block. Ignore them quickly.
363 Instruction *Inst = II;
364 if (Inst->use_empty()) continue;
365 if (Inst->hasOneUse() &&
366 cast<Instruction>(Inst->use_back())->getParent() == BB &&
367 !isa<PHINode>(Inst->use_back())) continue;
369 // If this is an alloca in the entry block, it's not a real register
371 if (AllocaInst *AI = dyn_cast<AllocaInst>(Inst))
372 if (isa<ConstantInt>(AI->getArraySize()) && BB == F->begin())
375 // Avoid iterator invalidation by copying users to a temporary vector.
376 std::vector<Instruction*> Users;
377 for (Value::use_iterator UI = Inst->use_begin(), E = Inst->use_end();
379 Instruction *User = cast<Instruction>(*UI);
380 if (User->getParent() != BB || isa<PHINode>(User))
381 Users.push_back(User);
384 // Scan all of the uses and see if the live range is live across an unwind
385 // edge. If we find a use live across an invoke edge, create an alloca
386 // and spill the value.
387 std::set<InvokeInst*> InvokesWithStoreInserted;
389 // Find all of the blocks that this value is live in.
390 std::set<BasicBlock*> LiveBBs;
391 LiveBBs.insert(Inst->getParent());
392 while (!Users.empty()) {
393 Instruction *U = Users.back();
396 if (!isa<PHINode>(U)) {
397 MarkBlocksLiveIn(U->getParent(), LiveBBs);
399 // Uses for a PHI node occur in their predecessor block.
400 PHINode *PN = cast<PHINode>(U);
401 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
402 if (PN->getIncomingValue(i) == Inst)
403 MarkBlocksLiveIn(PN->getIncomingBlock(i), LiveBBs);
407 // Now that we know all of the blocks that this thing is live in, see if
408 // it includes any of the unwind locations.
409 bool NeedsSpill = false;
410 for (unsigned i = 0, e = Invokes.size(); i != e; ++i) {
411 BasicBlock *UnwindBlock = Invokes[i]->getUnwindDest();
412 if (UnwindBlock != BB && LiveBBs.count(UnwindBlock)) {
417 // If we decided we need a spill, do it.
420 DemoteRegToStack(*Inst, true);
425 bool LowerInvoke::insertExpensiveEHSupport(Function &F) {
426 std::vector<ReturnInst*> Returns;
427 std::vector<UnwindInst*> Unwinds;
428 std::vector<InvokeInst*> Invokes;
430 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
431 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) {
432 // Remember all return instructions in case we insert an invoke into this
434 Returns.push_back(RI);
435 } else if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
436 Invokes.push_back(II);
437 } else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) {
438 Unwinds.push_back(UI);
441 if (Unwinds.empty() && Invokes.empty()) return false;
443 NumInvokes += Invokes.size();
444 NumUnwinds += Unwinds.size();
446 // TODO: This is not an optimal way to do this. In particular, this always
447 // inserts setjmp calls into the entries of functions with invoke instructions
448 // even though there are possibly paths through the function that do not
449 // execute any invokes. In particular, for functions with early exits, e.g.
450 // the 'addMove' method in hexxagon, it would be nice to not have to do the
451 // setjmp stuff on the early exit path. This requires a bit of dataflow, but
452 // would not be too hard to do.
454 // If we have an invoke instruction, insert a setjmp that dominates all
455 // invokes. After the setjmp, use a cond branch that goes to the original
456 // code path on zero, and to a designated 'catch' block of nonzero.
457 Value *OldJmpBufPtr = 0;
458 if (!Invokes.empty()) {
459 // First thing we need to do is scan the whole function for values that are
460 // live across unwind edges. Each value that is live across an unwind edge
461 // we spill into a stack location, guaranteeing that there is nothing live
462 // across the unwind edge. This process also splits all critical edges
463 // coming out of invoke's.
464 splitLiveRangesLiveAcrossInvokes(Invokes);
466 BasicBlock *EntryBB = F.begin();
468 // Create an alloca for the incoming jump buffer ptr and the new jump buffer
469 // that needs to be restored on all exits from the function. This is an
470 // alloca because the value needs to be live across invokes.
471 unsigned Align = TLI ? TLI->getJumpBufAlignment() : 0;
473 new AllocaInst(JBLinkTy, 0, Align, "jblink", F.begin()->begin());
475 std::vector<Value*> Idx;
476 Idx.push_back(Constant::getNullValue(Type::Int32Ty));
477 Idx.push_back(ConstantInt::get(Type::Int32Ty, 1));
478 OldJmpBufPtr = GetElementPtrInst::Create(JmpBuf, Idx.begin(), Idx.end(),
479 "OldBuf", EntryBB->getTerminator());
481 // Copy the JBListHead to the alloca.
482 Value *OldBuf = new LoadInst(JBListHead, "oldjmpbufptr", true,
483 EntryBB->getTerminator());
484 new StoreInst(OldBuf, OldJmpBufPtr, true, EntryBB->getTerminator());
486 // Add the new jumpbuf to the list.
487 new StoreInst(JmpBuf, JBListHead, true, EntryBB->getTerminator());
489 // Create the catch block. The catch block is basically a big switch
490 // statement that goes to all of the invoke catch blocks.
491 BasicBlock *CatchBB = BasicBlock::Create("setjmp.catch", &F);
493 // Create an alloca which keeps track of which invoke is currently
494 // executing. For normal calls it contains zero.
495 AllocaInst *InvokeNum = new AllocaInst(Type::Int32Ty, 0, "invokenum",
497 new StoreInst(ConstantInt::get(Type::Int32Ty, 0), InvokeNum, true,
498 EntryBB->getTerminator());
500 // Insert a load in the Catch block, and a switch on its value. By default,
501 // we go to a block that just does an unwind (which is the correct action
502 // for a standard call).
503 BasicBlock *UnwindBB = BasicBlock::Create("unwindbb", &F);
504 Unwinds.push_back(new UnwindInst(UnwindBB));
506 Value *CatchLoad = new LoadInst(InvokeNum, "invoke.num", true, CatchBB);
507 SwitchInst *CatchSwitch =
508 SwitchInst::Create(CatchLoad, UnwindBB, Invokes.size(), CatchBB);
510 // Now that things are set up, insert the setjmp call itself.
512 // Split the entry block to insert the conditional branch for the setjmp.
513 BasicBlock *ContBlock = EntryBB->splitBasicBlock(EntryBB->getTerminator(),
516 Idx[1] = ConstantInt::get(Type::Int32Ty, 0);
517 Value *JmpBufPtr = GetElementPtrInst::Create(JmpBuf, Idx.begin(), Idx.end(),
519 EntryBB->getTerminator());
520 JmpBufPtr = new BitCastInst(JmpBufPtr, PointerType::getUnqual(Type::Int8Ty),
521 "tmp", EntryBB->getTerminator());
522 Value *SJRet = CallInst::Create(SetJmpFn, JmpBufPtr, "sjret",
523 EntryBB->getTerminator());
525 // Compare the return value to zero.
526 Value *IsNormal = new ICmpInst(ICmpInst::ICMP_EQ, SJRet,
527 Constant::getNullValue(SJRet->getType()),
528 "notunwind", EntryBB->getTerminator());
529 // Nuke the uncond branch.
530 EntryBB->getTerminator()->eraseFromParent();
532 // Put in a new condbranch in its place.
533 BranchInst::Create(ContBlock, CatchBB, IsNormal, EntryBB);
535 // At this point, we are all set up, rewrite each invoke instruction.
536 for (unsigned i = 0, e = Invokes.size(); i != e; ++i)
537 rewriteExpensiveInvoke(Invokes[i], i+1, InvokeNum, CatchSwitch);
540 // We know that there is at least one unwind.
542 // Create three new blocks, the block to load the jmpbuf ptr and compare
543 // against null, the block to do the longjmp, and the error block for if it
544 // is null. Add them at the end of the function because they are not hot.
545 BasicBlock *UnwindHandler = BasicBlock::Create("dounwind", &F);
546 BasicBlock *UnwindBlock = BasicBlock::Create("unwind", &F);
547 BasicBlock *TermBlock = BasicBlock::Create("unwinderror", &F);
549 // If this function contains an invoke, restore the old jumpbuf ptr.
552 // Before the return, insert a copy from the saved value to the new value.
553 BufPtr = new LoadInst(OldJmpBufPtr, "oldjmpbufptr", UnwindHandler);
554 new StoreInst(BufPtr, JBListHead, UnwindHandler);
556 BufPtr = new LoadInst(JBListHead, "ehlist", UnwindHandler);
559 // Load the JBList, if it's null, then there was no catch!
560 Value *NotNull = new ICmpInst(ICmpInst::ICMP_NE, BufPtr,
561 Constant::getNullValue(BufPtr->getType()),
562 "notnull", UnwindHandler);
563 BranchInst::Create(UnwindBlock, TermBlock, NotNull, UnwindHandler);
565 // Create the block to do the longjmp.
566 // Get a pointer to the jmpbuf and longjmp.
567 std::vector<Value*> Idx;
568 Idx.push_back(Constant::getNullValue(Type::Int32Ty));
569 Idx.push_back(ConstantInt::get(Type::Int32Ty, 0));
570 Idx[0] = GetElementPtrInst::Create(BufPtr, Idx.begin(), Idx.end(), "JmpBuf",
572 Idx[0] = new BitCastInst(Idx[0], PointerType::getUnqual(Type::Int8Ty),
574 Idx[1] = ConstantInt::get(Type::Int32Ty, 1);
575 CallInst::Create(LongJmpFn, Idx.begin(), Idx.end(), "", UnwindBlock);
576 new UnreachableInst(UnwindBlock);
578 // Set up the term block ("throw without a catch").
579 new UnreachableInst(TermBlock);
581 // Insert a new call to write(2, AbortMessage, AbortMessageLength);
582 writeAbortMessage(TermBlock->getTerminator());
584 // Insert a call to abort()
585 CallInst::Create(AbortFn, "",
586 TermBlock->getTerminator())->setTailCall();
589 // Replace all unwinds with a branch to the unwind handler.
590 for (unsigned i = 0, e = Unwinds.size(); i != e; ++i) {
591 BranchInst::Create(UnwindHandler, Unwinds[i]);
592 Unwinds[i]->eraseFromParent();
595 // Finally, for any returns from this function, if this function contains an
596 // invoke, restore the old jmpbuf pointer to its input value.
598 for (unsigned i = 0, e = Returns.size(); i != e; ++i) {
599 ReturnInst *R = Returns[i];
601 // Before the return, insert a copy from the saved value to the new value.
602 Value *OldBuf = new LoadInst(OldJmpBufPtr, "oldjmpbufptr", true, R);
603 new StoreInst(OldBuf, JBListHead, true, R);
610 bool LowerInvoke::runOnFunction(Function &F) {
611 if (ExpensiveEHSupport)
612 return insertExpensiveEHSupport(F);
614 return insertCheapEHSupport(F);