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 const Type *VoidPtrTy = Context->getPointerTypeUnqual(Type::Int8Ty);
120 if (ExpensiveEHSupport) {
121 // Insert a type for the linked list of jump buffers.
122 unsigned JBSize = TLI ? TLI->getJumpBufSize() : 0;
123 JBSize = JBSize ? JBSize : 200;
124 const Type *JmpBufTy = Context->getArrayType(VoidPtrTy, JBSize);
126 { // The type is recursive, so use a type holder.
127 std::vector<const Type*> Elements;
128 Elements.push_back(JmpBufTy);
129 OpaqueType *OT = Context->getOpaqueType();
130 Elements.push_back(Context->getPointerTypeUnqual(OT));
131 PATypeHolder JBLType(Context->getStructType(Elements));
132 OT->refineAbstractTypeTo(JBLType.get()); // Complete the cycle.
133 JBLinkTy = JBLType.get();
134 M.addTypeName("llvm.sjljeh.jmpbufty", JBLinkTy);
137 const Type *PtrJBList = Context->getPointerTypeUnqual(JBLinkTy);
139 // Now that we've done that, insert the jmpbuf list head global, unless it
141 if (!(JBListHead = M.getGlobalVariable("llvm.sjljeh.jblist", PtrJBList))) {
142 JBListHead = new GlobalVariable(M.getContext(),
144 GlobalValue::LinkOnceAnyLinkage,
145 Context->getNullValue(PtrJBList),
146 "llvm.sjljeh.jblist", &M);
149 // VisualStudio defines setjmp as _setjmp via #include <csetjmp> / <setjmp.h>,
150 // so it looks like Intrinsic::_setjmp
151 #if defined(_MSC_VER) && defined(setjmp)
152 #define setjmp_undefined_for_visual_studio
156 SetJmpFn = Intrinsic::getDeclaration(&M, Intrinsic::setjmp);
158 #if defined(_MSC_VER) && defined(setjmp_undefined_for_visual_studio)
159 // let's return it to _setjmp state in case anyone ever needs it after this
160 // point under VisualStudio
161 #define setjmp _setjmp
164 LongJmpFn = Intrinsic::getDeclaration(&M, Intrinsic::longjmp);
167 // We need the 'write' and 'abort' functions for both models.
168 AbortFn = M.getOrInsertFunction("abort", Type::VoidTy, (Type *)0);
169 #if 0 // "write" is Unix-specific.. code is going away soon anyway.
170 WriteFn = M.getOrInsertFunction("write", Type::VoidTy, Type::Int32Ty,
171 VoidPtrTy, Type::Int32Ty, (Type *)0);
178 void LowerInvoke::createAbortMessage(Module *M) {
179 if (ExpensiveEHSupport) {
180 // The abort message for expensive EH support tells the user that the
181 // program 'unwound' without an 'invoke' instruction.
183 Context->getConstantArray("ERROR: Exception thrown, but not caught!\n");
184 AbortMessageLength = Msg->getNumOperands()-1; // don't include \0
186 GlobalVariable *MsgGV = new GlobalVariable(M->getContext(),
187 Msg->getType(), true,
188 GlobalValue::InternalLinkage,
190 std::vector<Constant*> GEPIdx(2, Context->getNullValue(Type::Int32Ty));
191 AbortMessage = Context->getConstantExprGetElementPtr(MsgGV, &GEPIdx[0], 2);
193 // The abort message for cheap EH support tells the user that EH is not
196 Context->getConstantArray("Exception handler needed, but not enabled."
197 "Recompile program with -enable-correct-eh-support.\n");
198 AbortMessageLength = Msg->getNumOperands()-1; // don't include \0
200 GlobalVariable *MsgGV = new GlobalVariable(M->getContext(),
201 Msg->getType(), true,
202 GlobalValue::InternalLinkage,
204 std::vector<Constant*> GEPIdx(2, Context->getNullValue(Type::Int32Ty));
205 AbortMessage = ConstantExpr::getGetElementPtr(MsgGV, &GEPIdx[0], 2);
210 void LowerInvoke::writeAbortMessage(Instruction *IB) {
212 if (AbortMessage == 0)
213 createAbortMessage(IB->getParent()->getParent()->getParent());
215 // These are the arguments we WANT...
217 Args[0] = ConstantInt::get(Type::Int32Ty, 2);
218 Args[1] = AbortMessage;
219 Args[2] = ConstantInt::get(Type::Int32Ty, AbortMessageLength);
220 (new CallInst(WriteFn, Args, 3, "", IB))->setTailCall();
224 bool LowerInvoke::insertCheapEHSupport(Function &F) {
225 bool Changed = false;
226 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
227 if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
228 std::vector<Value*> CallArgs(II->op_begin()+3, II->op_end());
229 // Insert a normal call instruction...
230 CallInst *NewCall = CallInst::Create(II->getCalledValue(),
231 CallArgs.begin(), CallArgs.end(), "",II);
232 NewCall->takeName(II);
233 NewCall->setCallingConv(II->getCallingConv());
234 NewCall->setAttributes(II->getAttributes());
235 II->replaceAllUsesWith(NewCall);
237 // Insert an unconditional branch to the normal destination.
238 BranchInst::Create(II->getNormalDest(), II);
240 // Remove any PHI node entries from the exception destination.
241 II->getUnwindDest()->removePredecessor(BB);
243 // Remove the invoke instruction now.
244 BB->getInstList().erase(II);
246 ++NumInvokes; Changed = true;
247 } else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) {
248 // Insert a new call to write(2, AbortMessage, AbortMessageLength);
249 writeAbortMessage(UI);
251 // Insert a call to abort()
252 CallInst::Create(AbortFn, "", UI)->setTailCall();
254 // Insert a return instruction. This really should be a "barrier", as it
256 ReturnInst::Create(F.getReturnType() == Type::VoidTy ? 0 :
257 Constant::getNullValue(F.getReturnType()), UI);
259 // Remove the unwind instruction now.
260 BB->getInstList().erase(UI);
262 ++NumUnwinds; Changed = true;
267 /// rewriteExpensiveInvoke - Insert code and hack the function to replace the
268 /// specified invoke instruction with a call.
269 void LowerInvoke::rewriteExpensiveInvoke(InvokeInst *II, unsigned InvokeNo,
270 AllocaInst *InvokeNum,
271 SwitchInst *CatchSwitch) {
272 ConstantInt *InvokeNoC = ConstantInt::get(Type::Int32Ty, InvokeNo);
274 // If the unwind edge has phi nodes, split the edge.
275 if (isa<PHINode>(II->getUnwindDest()->begin())) {
276 SplitCriticalEdge(II, 1, this);
278 // If there are any phi nodes left, they must have a single predecessor.
279 while (PHINode *PN = dyn_cast<PHINode>(II->getUnwindDest()->begin())) {
280 PN->replaceAllUsesWith(PN->getIncomingValue(0));
281 PN->eraseFromParent();
285 // Insert a store of the invoke num before the invoke and store zero into the
286 // location afterward.
287 new StoreInst(InvokeNoC, InvokeNum, true, II); // volatile
289 BasicBlock::iterator NI = II->getNormalDest()->getFirstNonPHI();
291 new StoreInst(Constant::getNullValue(Type::Int32Ty), InvokeNum, false, NI);
293 // Add a switch case to our unwind block.
294 CatchSwitch->addCase(InvokeNoC, II->getUnwindDest());
296 // Insert a normal call instruction.
297 std::vector<Value*> CallArgs(II->op_begin()+3, II->op_end());
298 CallInst *NewCall = CallInst::Create(II->getCalledValue(),
299 CallArgs.begin(), CallArgs.end(), "",
301 NewCall->takeName(II);
302 NewCall->setCallingConv(II->getCallingConv());
303 NewCall->setAttributes(II->getAttributes());
304 II->replaceAllUsesWith(NewCall);
306 // Replace the invoke with an uncond branch.
307 BranchInst::Create(II->getNormalDest(), NewCall->getParent());
308 II->eraseFromParent();
311 /// MarkBlocksLiveIn - Insert BB and all of its predescessors into LiveBBs until
312 /// we reach blocks we've already seen.
313 static void MarkBlocksLiveIn(BasicBlock *BB, std::set<BasicBlock*> &LiveBBs) {
314 if (!LiveBBs.insert(BB).second) return; // already been here.
316 for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
317 MarkBlocksLiveIn(*PI, LiveBBs);
320 // First thing we need to do is scan the whole function for values that are
321 // live across unwind edges. Each value that is live across an unwind edge
322 // we spill into a stack location, guaranteeing that there is nothing live
323 // across the unwind edge. This process also splits all critical edges
324 // coming out of invoke's.
326 splitLiveRangesLiveAcrossInvokes(std::vector<InvokeInst*> &Invokes) {
327 // First step, split all critical edges from invoke instructions.
328 for (unsigned i = 0, e = Invokes.size(); i != e; ++i) {
329 InvokeInst *II = Invokes[i];
330 SplitCriticalEdge(II, 0, this);
331 SplitCriticalEdge(II, 1, this);
332 assert(!isa<PHINode>(II->getNormalDest()) &&
333 !isa<PHINode>(II->getUnwindDest()) &&
334 "critical edge splitting left single entry phi nodes?");
337 Function *F = Invokes.back()->getParent()->getParent();
339 // To avoid having to handle incoming arguments specially, we lower each arg
340 // to a copy instruction in the entry block. This ensures that the argument
341 // value itself cannot be live across the entry block.
342 BasicBlock::iterator AfterAllocaInsertPt = F->begin()->begin();
343 while (isa<AllocaInst>(AfterAllocaInsertPt) &&
344 isa<ConstantInt>(cast<AllocaInst>(AfterAllocaInsertPt)->getArraySize()))
345 ++AfterAllocaInsertPt;
346 for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
348 // This is always a no-op cast because we're casting AI to AI->getType() so
349 // src and destination types are identical. BitCast is the only possibility.
350 CastInst *NC = new BitCastInst(
351 AI, AI->getType(), AI->getName()+".tmp", AfterAllocaInsertPt);
352 AI->replaceAllUsesWith(NC);
353 // Normally its is forbidden to replace a CastInst's operand because it
354 // could cause the opcode to reflect an illegal conversion. However, we're
355 // replacing it here with the same value it was constructed with to simply
357 NC->setOperand(0, AI);
360 // Finally, scan the code looking for instructions with bad live ranges.
361 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
362 for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ++II) {
363 // Ignore obvious cases we don't have to handle. In particular, most
364 // instructions either have no uses or only have a single use inside the
365 // current block. Ignore them quickly.
366 Instruction *Inst = II;
367 if (Inst->use_empty()) continue;
368 if (Inst->hasOneUse() &&
369 cast<Instruction>(Inst->use_back())->getParent() == BB &&
370 !isa<PHINode>(Inst->use_back())) continue;
372 // If this is an alloca in the entry block, it's not a real register
374 if (AllocaInst *AI = dyn_cast<AllocaInst>(Inst))
375 if (isa<ConstantInt>(AI->getArraySize()) && BB == F->begin())
378 // Avoid iterator invalidation by copying users to a temporary vector.
379 std::vector<Instruction*> Users;
380 for (Value::use_iterator UI = Inst->use_begin(), E = Inst->use_end();
382 Instruction *User = cast<Instruction>(*UI);
383 if (User->getParent() != BB || isa<PHINode>(User))
384 Users.push_back(User);
387 // Scan all of the uses and see if the live range is live across an unwind
388 // edge. If we find a use live across an invoke edge, create an alloca
389 // and spill the value.
390 std::set<InvokeInst*> InvokesWithStoreInserted;
392 // Find all of the blocks that this value is live in.
393 std::set<BasicBlock*> LiveBBs;
394 LiveBBs.insert(Inst->getParent());
395 while (!Users.empty()) {
396 Instruction *U = Users.back();
399 if (!isa<PHINode>(U)) {
400 MarkBlocksLiveIn(U->getParent(), LiveBBs);
402 // Uses for a PHI node occur in their predecessor block.
403 PHINode *PN = cast<PHINode>(U);
404 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
405 if (PN->getIncomingValue(i) == Inst)
406 MarkBlocksLiveIn(PN->getIncomingBlock(i), LiveBBs);
410 // Now that we know all of the blocks that this thing is live in, see if
411 // it includes any of the unwind locations.
412 bool NeedsSpill = false;
413 for (unsigned i = 0, e = Invokes.size(); i != e; ++i) {
414 BasicBlock *UnwindBlock = Invokes[i]->getUnwindDest();
415 if (UnwindBlock != BB && LiveBBs.count(UnwindBlock)) {
420 // If we decided we need a spill, do it.
423 DemoteRegToStack(*Inst, true);
428 bool LowerInvoke::insertExpensiveEHSupport(Function &F) {
429 std::vector<ReturnInst*> Returns;
430 std::vector<UnwindInst*> Unwinds;
431 std::vector<InvokeInst*> Invokes;
433 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
434 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) {
435 // Remember all return instructions in case we insert an invoke into this
437 Returns.push_back(RI);
438 } else if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
439 Invokes.push_back(II);
440 } else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) {
441 Unwinds.push_back(UI);
444 if (Unwinds.empty() && Invokes.empty()) return false;
446 NumInvokes += Invokes.size();
447 NumUnwinds += Unwinds.size();
449 // TODO: This is not an optimal way to do this. In particular, this always
450 // inserts setjmp calls into the entries of functions with invoke instructions
451 // even though there are possibly paths through the function that do not
452 // execute any invokes. In particular, for functions with early exits, e.g.
453 // the 'addMove' method in hexxagon, it would be nice to not have to do the
454 // setjmp stuff on the early exit path. This requires a bit of dataflow, but
455 // would not be too hard to do.
457 // If we have an invoke instruction, insert a setjmp that dominates all
458 // invokes. After the setjmp, use a cond branch that goes to the original
459 // code path on zero, and to a designated 'catch' block of nonzero.
460 Value *OldJmpBufPtr = 0;
461 if (!Invokes.empty()) {
462 // First thing we need to do is scan the whole function for values that are
463 // live across unwind edges. Each value that is live across an unwind edge
464 // we spill into a stack location, guaranteeing that there is nothing live
465 // across the unwind edge. This process also splits all critical edges
466 // coming out of invoke's.
467 splitLiveRangesLiveAcrossInvokes(Invokes);
469 BasicBlock *EntryBB = F.begin();
471 // Create an alloca for the incoming jump buffer ptr and the new jump buffer
472 // that needs to be restored on all exits from the function. This is an
473 // alloca because the value needs to be live across invokes.
474 unsigned Align = TLI ? TLI->getJumpBufAlignment() : 0;
476 new AllocaInst(JBLinkTy, 0, Align, "jblink", F.begin()->begin());
478 std::vector<Value*> Idx;
479 Idx.push_back(Constant::getNullValue(Type::Int32Ty));
480 Idx.push_back(ConstantInt::get(Type::Int32Ty, 1));
481 OldJmpBufPtr = GetElementPtrInst::Create(JmpBuf, Idx.begin(), Idx.end(),
482 "OldBuf", EntryBB->getTerminator());
484 // Copy the JBListHead to the alloca.
485 Value *OldBuf = new LoadInst(JBListHead, "oldjmpbufptr", true,
486 EntryBB->getTerminator());
487 new StoreInst(OldBuf, OldJmpBufPtr, true, EntryBB->getTerminator());
489 // Add the new jumpbuf to the list.
490 new StoreInst(JmpBuf, JBListHead, true, EntryBB->getTerminator());
492 // Create the catch block. The catch block is basically a big switch
493 // statement that goes to all of the invoke catch blocks.
494 BasicBlock *CatchBB = BasicBlock::Create("setjmp.catch", &F);
496 // Create an alloca which keeps track of which invoke is currently
497 // executing. For normal calls it contains zero.
498 AllocaInst *InvokeNum = new AllocaInst(Type::Int32Ty, 0, "invokenum",
500 new StoreInst(ConstantInt::get(Type::Int32Ty, 0), InvokeNum, true,
501 EntryBB->getTerminator());
503 // Insert a load in the Catch block, and a switch on its value. By default,
504 // we go to a block that just does an unwind (which is the correct action
505 // for a standard call).
506 BasicBlock *UnwindBB = BasicBlock::Create("unwindbb", &F);
507 Unwinds.push_back(new UnwindInst(UnwindBB));
509 Value *CatchLoad = new LoadInst(InvokeNum, "invoke.num", true, CatchBB);
510 SwitchInst *CatchSwitch =
511 SwitchInst::Create(CatchLoad, UnwindBB, Invokes.size(), CatchBB);
513 // Now that things are set up, insert the setjmp call itself.
515 // Split the entry block to insert the conditional branch for the setjmp.
516 BasicBlock *ContBlock = EntryBB->splitBasicBlock(EntryBB->getTerminator(),
519 Idx[1] = ConstantInt::get(Type::Int32Ty, 0);
520 Value *JmpBufPtr = GetElementPtrInst::Create(JmpBuf, Idx.begin(), Idx.end(),
522 EntryBB->getTerminator());
523 JmpBufPtr = new BitCastInst(JmpBufPtr, PointerType::getUnqual(Type::Int8Ty),
524 "tmp", EntryBB->getTerminator());
525 Value *SJRet = CallInst::Create(SetJmpFn, JmpBufPtr, "sjret",
526 EntryBB->getTerminator());
528 // Compare the return value to zero.
529 Value *IsNormal = new ICmpInst(ICmpInst::ICMP_EQ, SJRet,
530 Constant::getNullValue(SJRet->getType()),
531 "notunwind", EntryBB->getTerminator());
532 // Nuke the uncond branch.
533 EntryBB->getTerminator()->eraseFromParent();
535 // Put in a new condbranch in its place.
536 BranchInst::Create(ContBlock, CatchBB, IsNormal, EntryBB);
538 // At this point, we are all set up, rewrite each invoke instruction.
539 for (unsigned i = 0, e = Invokes.size(); i != e; ++i)
540 rewriteExpensiveInvoke(Invokes[i], i+1, InvokeNum, CatchSwitch);
543 // We know that there is at least one unwind.
545 // Create three new blocks, the block to load the jmpbuf ptr and compare
546 // against null, the block to do the longjmp, and the error block for if it
547 // is null. Add them at the end of the function because they are not hot.
548 BasicBlock *UnwindHandler = BasicBlock::Create("dounwind", &F);
549 BasicBlock *UnwindBlock = BasicBlock::Create("unwind", &F);
550 BasicBlock *TermBlock = BasicBlock::Create("unwinderror", &F);
552 // If this function contains an invoke, restore the old jumpbuf ptr.
555 // Before the return, insert a copy from the saved value to the new value.
556 BufPtr = new LoadInst(OldJmpBufPtr, "oldjmpbufptr", UnwindHandler);
557 new StoreInst(BufPtr, JBListHead, UnwindHandler);
559 BufPtr = new LoadInst(JBListHead, "ehlist", UnwindHandler);
562 // Load the JBList, if it's null, then there was no catch!
563 Value *NotNull = new ICmpInst(ICmpInst::ICMP_NE, BufPtr,
564 Constant::getNullValue(BufPtr->getType()),
565 "notnull", UnwindHandler);
566 BranchInst::Create(UnwindBlock, TermBlock, NotNull, UnwindHandler);
568 // Create the block to do the longjmp.
569 // Get a pointer to the jmpbuf and longjmp.
570 std::vector<Value*> Idx;
571 Idx.push_back(Constant::getNullValue(Type::Int32Ty));
572 Idx.push_back(ConstantInt::get(Type::Int32Ty, 0));
573 Idx[0] = GetElementPtrInst::Create(BufPtr, Idx.begin(), Idx.end(), "JmpBuf",
575 Idx[0] = new BitCastInst(Idx[0], PointerType::getUnqual(Type::Int8Ty),
577 Idx[1] = ConstantInt::get(Type::Int32Ty, 1);
578 CallInst::Create(LongJmpFn, Idx.begin(), Idx.end(), "", UnwindBlock);
579 new UnreachableInst(UnwindBlock);
581 // Set up the term block ("throw without a catch").
582 new UnreachableInst(TermBlock);
584 // Insert a new call to write(2, AbortMessage, AbortMessageLength);
585 writeAbortMessage(TermBlock->getTerminator());
587 // Insert a call to abort()
588 CallInst::Create(AbortFn, "",
589 TermBlock->getTerminator())->setTailCall();
592 // Replace all unwinds with a branch to the unwind handler.
593 for (unsigned i = 0, e = Unwinds.size(); i != e; ++i) {
594 BranchInst::Create(UnwindHandler, Unwinds[i]);
595 Unwinds[i]->eraseFromParent();
598 // Finally, for any returns from this function, if this function contains an
599 // invoke, restore the old jmpbuf pointer to its input value.
601 for (unsigned i = 0, e = Returns.size(); i != e; ++i) {
602 ReturnInst *R = Returns[i];
604 // Before the return, insert a copy from the saved value to the new value.
605 Value *OldBuf = new LoadInst(OldJmpBufPtr, "oldjmpbufptr", true, R);
606 new StoreInst(OldBuf, JBListHead, true, R);
613 bool LowerInvoke::runOnFunction(Function &F) {
614 if (ExpensiveEHSupport)
615 return insertExpensiveEHSupport(F);
617 return insertCheapEHSupport(F);