1 //===- SjLjEHPass.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 use SjLj
11 // based exception handling.
13 //===----------------------------------------------------------------------===//
15 #define DEBUG_TYPE "sjljehprepare"
16 #include "llvm/Transforms/Scalar.h"
17 #include "llvm/Constants.h"
18 #include "llvm/DerivedTypes.h"
19 #include "llvm/Instructions.h"
20 #include "llvm/Intrinsics.h"
21 #include "llvm/LLVMContext.h"
22 #include "llvm/Module.h"
23 #include "llvm/Pass.h"
24 #include "llvm/CodeGen/Passes.h"
25 #include "llvm/Target/TargetLowering.h"
26 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
27 #include "llvm/Transforms/Utils/Local.h"
28 #include "llvm/Support/Debug.h"
29 #include "llvm/ADT/DenseMap.h"
30 #include "llvm/ADT/SmallVector.h"
31 #include "llvm/ADT/Statistic.h"
35 STATISTIC(NumInvokes, "Number of invokes replaced");
36 STATISTIC(NumUnwinds, "Number of unwinds replaced");
37 STATISTIC(NumSpilled, "Number of registers live across unwind edges");
40 class SjLjEHPass : public FunctionPass {
41 const TargetLowering *TLI;
42 Type *FunctionContextTy;
44 Constant *UnregisterFn;
45 Constant *BuiltinSetjmpFn;
46 Constant *FrameAddrFn;
47 Constant *StackAddrFn;
48 Constant *StackRestoreFn;
52 Constant *ExceptionFn;
54 Constant *DispatchSetupFn;
56 DenseMap<InvokeInst*, BasicBlock*> LPadSuccMap;
58 static char ID; // Pass identification, replacement for typeid
59 explicit SjLjEHPass(const TargetLowering *tli = NULL)
60 : FunctionPass(ID), TLI(tli) { }
61 bool doInitialization(Module &M);
62 bool runOnFunction(Function &F);
64 virtual void getAnalysisUsage(AnalysisUsage &AU) const {}
65 const char *getPassName() const {
66 return "SJLJ Exception Handling preparation";
70 void insertCallSiteStore(Instruction *I, int Number, Value *CallSite);
71 void markInvokeCallSite(InvokeInst *II, int InvokeNo, Value *CallSite,
72 SwitchInst *CatchSwitch);
73 void splitLiveRangesAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes);
74 bool insertSjLjEHSupport(Function &F);
76 } // end anonymous namespace
78 char SjLjEHPass::ID = 0;
80 // Public Interface To the SjLjEHPass pass.
81 FunctionPass *llvm::createSjLjEHPass(const TargetLowering *TLI) {
82 return new SjLjEHPass(TLI);
84 // doInitialization - Set up decalarations and types needed to process
86 bool SjLjEHPass::doInitialization(Module &M) {
87 // Build the function context structure.
88 // builtin_setjmp uses a five word jbuf
89 Type *VoidPtrTy = Type::getInt8PtrTy(M.getContext());
90 Type *Int32Ty = Type::getInt32Ty(M.getContext());
92 StructType::get(VoidPtrTy, // __prev
94 ArrayType::get(Int32Ty, 4), // __data
95 VoidPtrTy, // __personality
97 ArrayType::get(VoidPtrTy, 5), // __jbuf
99 RegisterFn = M.getOrInsertFunction("_Unwind_SjLj_Register",
100 Type::getVoidTy(M.getContext()),
101 PointerType::getUnqual(FunctionContextTy),
104 M.getOrInsertFunction("_Unwind_SjLj_Unregister",
105 Type::getVoidTy(M.getContext()),
106 PointerType::getUnqual(FunctionContextTy),
108 FrameAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::frameaddress);
109 StackAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::stacksave);
110 StackRestoreFn = Intrinsic::getDeclaration(&M, Intrinsic::stackrestore);
111 BuiltinSetjmpFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_setjmp);
112 LSDAAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_lsda);
113 SelectorFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_selector);
114 ExceptionFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_exception);
115 CallSiteFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_callsite);
117 = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_dispatch_setup);
123 /// insertCallSiteStore - Insert a store of the call-site value to the
125 void SjLjEHPass::insertCallSiteStore(Instruction *I, int Number,
127 ConstantInt *CallSiteNoC = ConstantInt::get(Type::getInt32Ty(I->getContext()),
129 // Insert a store of the call-site number
130 new StoreInst(CallSiteNoC, CallSite, true, I); // volatile
133 /// markInvokeCallSite - Insert code to mark the call_site for this invoke
134 void SjLjEHPass::markInvokeCallSite(InvokeInst *II, int InvokeNo,
136 SwitchInst *CatchSwitch) {
137 ConstantInt *CallSiteNoC= ConstantInt::get(Type::getInt32Ty(II->getContext()),
139 // The runtime comes back to the dispatcher with the call_site - 1 in
140 // the context. Odd, but there it is.
141 ConstantInt *SwitchValC = ConstantInt::get(Type::getInt32Ty(II->getContext()),
144 // If the unwind edge has phi nodes, split the edge.
145 if (isa<PHINode>(II->getUnwindDest()->begin())) {
146 // FIXME: New EH - This if-condition will be always true in the new scheme.
147 if (II->getUnwindDest()->isLandingPad()) {
148 SmallVector<BasicBlock*, 2> NewBBs;
149 SplitLandingPadPredecessors(II->getUnwindDest(), II->getParent(),
150 ".1", ".2", this, NewBBs);
151 LPadSuccMap[II] = *succ_begin(NewBBs[0]);
153 SplitCriticalEdge(II, 1, this);
156 // If there are any phi nodes left, they must have a single predecessor.
157 while (PHINode *PN = dyn_cast<PHINode>(II->getUnwindDest()->begin())) {
158 PN->replaceAllUsesWith(PN->getIncomingValue(0));
159 PN->eraseFromParent();
163 // Insert the store of the call site value
164 insertCallSiteStore(II, InvokeNo, CallSite);
166 // Record the call site value for the back end so it stays associated with
168 CallInst::Create(CallSiteFn, CallSiteNoC, "", II);
170 // Add a switch case to our unwind block.
171 if (BasicBlock *SuccBB = LPadSuccMap[II]) {
172 CatchSwitch->addCase(SwitchValC, SuccBB);
174 CatchSwitch->addCase(SwitchValC, II->getUnwindDest());
177 // We still want this to look like an invoke so we emit the LSDA properly,
178 // so we don't transform the invoke into a call here.
181 /// MarkBlocksLiveIn - Insert BB and all of its predescessors into LiveBBs until
182 /// we reach blocks we've already seen.
183 static void MarkBlocksLiveIn(BasicBlock *BB, std::set<BasicBlock*> &LiveBBs) {
184 if (!LiveBBs.insert(BB).second) return; // already been here.
186 for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
187 MarkBlocksLiveIn(*PI, LiveBBs);
190 /// splitLiveRangesAcrossInvokes - Each value that is live across an unwind edge
191 /// we spill into a stack location, guaranteeing that there is nothing live
192 /// across the unwind edge. This process also splits all critical edges
193 /// coming out of invoke's.
194 /// FIXME: Move this function to a common utility file (Local.cpp?) so
195 /// both SjLj and LowerInvoke can use it.
197 splitLiveRangesAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes) {
198 // First step, split all critical edges from invoke instructions.
199 for (unsigned i = 0, e = Invokes.size(); i != e; ++i) {
200 InvokeInst *II = Invokes[i];
201 SplitCriticalEdge(II, 0, this);
203 // FIXME: New EH - This if-condition will be always true in the new scheme.
204 if (II->getUnwindDest()->isLandingPad()) {
205 SmallVector<BasicBlock*, 2> NewBBs;
206 SplitLandingPadPredecessors(II->getUnwindDest(), II->getParent(),
207 ".1", ".2", this, NewBBs);
208 LPadSuccMap[II] = *succ_begin(NewBBs[0]);
210 SplitCriticalEdge(II, 1, this);
213 assert(!isa<PHINode>(II->getNormalDest()) &&
214 !isa<PHINode>(II->getUnwindDest()) &&
215 "Critical edge splitting left single entry phi nodes?");
218 Function *F = Invokes.back()->getParent()->getParent();
220 // To avoid having to handle incoming arguments specially, we lower each arg
221 // to a copy instruction in the entry block. This ensures that the argument
222 // value itself cannot be live across the entry block.
223 BasicBlock::iterator AfterAllocaInsertPt = F->begin()->begin();
224 while (isa<AllocaInst>(AfterAllocaInsertPt) &&
225 isa<ConstantInt>(cast<AllocaInst>(AfterAllocaInsertPt)->getArraySize()))
226 ++AfterAllocaInsertPt;
227 for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
229 Type *Ty = AI->getType();
230 // Aggregate types can't be cast, but are legal argument types, so we have
231 // to handle them differently. We use an extract/insert pair as a
232 // lightweight method to achieve the same goal.
233 if (isa<StructType>(Ty) || isa<ArrayType>(Ty) || isa<VectorType>(Ty)) {
234 Instruction *EI = ExtractValueInst::Create(AI, 0, "",AfterAllocaInsertPt);
235 Instruction *NI = InsertValueInst::Create(AI, EI, 0);
237 AI->replaceAllUsesWith(NI);
238 // Set the operand of the instructions back to the AllocaInst.
239 EI->setOperand(0, AI);
240 NI->setOperand(0, AI);
242 // This is always a no-op cast because we're casting AI to AI->getType()
243 // so src and destination types are identical. BitCast is the only
245 CastInst *NC = new BitCastInst(
246 AI, AI->getType(), AI->getName()+".tmp", AfterAllocaInsertPt);
247 AI->replaceAllUsesWith(NC);
248 // Set the operand of the cast instruction back to the AllocaInst.
249 // Normally it's forbidden to replace a CastInst's operand because it
250 // could cause the opcode to reflect an illegal conversion. However,
251 // we're replacing it here with the same value it was constructed with.
252 // We do this because the above replaceAllUsesWith() clobbered the
253 // operand, but we want this one to remain.
254 NC->setOperand(0, AI);
258 // Finally, scan the code looking for instructions with bad live ranges.
259 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
260 for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ++II) {
261 // Ignore obvious cases we don't have to handle. In particular, most
262 // instructions either have no uses or only have a single use inside the
263 // current block. Ignore them quickly.
264 Instruction *Inst = II;
265 if (Inst->use_empty()) continue;
266 if (Inst->hasOneUse() &&
267 cast<Instruction>(Inst->use_back())->getParent() == BB &&
268 !isa<PHINode>(Inst->use_back())) continue;
270 // If this is an alloca in the entry block, it's not a real register
272 if (AllocaInst *AI = dyn_cast<AllocaInst>(Inst))
273 if (isa<ConstantInt>(AI->getArraySize()) && BB == F->begin())
276 // Avoid iterator invalidation by copying users to a temporary vector.
277 SmallVector<Instruction*,16> Users;
278 for (Value::use_iterator UI = Inst->use_begin(), E = Inst->use_end();
280 Instruction *User = cast<Instruction>(*UI);
281 if (User->getParent() != BB || isa<PHINode>(User))
282 Users.push_back(User);
285 // Find all of the blocks that this value is live in.
286 std::set<BasicBlock*> LiveBBs;
287 LiveBBs.insert(Inst->getParent());
288 while (!Users.empty()) {
289 Instruction *U = Users.back();
292 if (!isa<PHINode>(U)) {
293 MarkBlocksLiveIn(U->getParent(), LiveBBs);
295 // Uses for a PHI node occur in their predecessor block.
296 PHINode *PN = cast<PHINode>(U);
297 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
298 if (PN->getIncomingValue(i) == Inst)
299 MarkBlocksLiveIn(PN->getIncomingBlock(i), LiveBBs);
303 // Now that we know all of the blocks that this thing is live in, see if
304 // it includes any of the unwind locations.
305 bool NeedsSpill = false;
306 for (unsigned i = 0, e = Invokes.size(); i != e; ++i) {
307 BasicBlock *UnwindBlock = Invokes[i]->getUnwindDest();
308 if (UnwindBlock != BB && LiveBBs.count(UnwindBlock)) {
313 // If we decided we need a spill, do it.
314 // FIXME: Spilling this way is overkill, as it forces all uses of
315 // the value to be reloaded from the stack slot, even those that aren't
316 // in the unwind blocks. We should be more selective.
319 DemoteRegToStack(*Inst, true);
324 /// CreateLandingPadLoad - Load the exception handling values and insert them
325 /// into a structure.
326 static Instruction *CreateLandingPadLoad(Function &F, Value *ExnAddr,
328 BasicBlock::iterator InsertPt) {
329 Value *Exn = new LoadInst(ExnAddr, "exn", false,
331 Type *Ty = Type::getInt8PtrTy(F.getContext());
332 Exn = CastInst::Create(Instruction::IntToPtr, Exn, Ty, "", InsertPt);
333 Value *Sel = new LoadInst(SelAddr, "sel", false, InsertPt);
335 Ty = StructType::get(Exn->getType(), Sel->getType(), NULL);
336 InsertValueInst *LPadVal = InsertValueInst::Create(llvm::UndefValue::get(Ty),
338 "lpad.val", InsertPt);
339 return InsertValueInst::Create(LPadVal, Sel, 1, "lpad.val", InsertPt);
342 /// ReplaceLandingPadVal - Replace the landingpad instruction's value with a
343 /// load from the stored values (via CreateLandingPadLoad). This looks through
344 /// PHI nodes, and removes them if they are dead.
345 static void ReplaceLandingPadVal(Function &F, Instruction *Inst, Value *ExnAddr,
347 if (Inst->use_empty()) return;
349 while (!Inst->use_empty()) {
350 Instruction *I = cast<Instruction>(Inst->use_back());
352 if (PHINode *PN = dyn_cast<PHINode>(I)) {
353 ReplaceLandingPadVal(F, PN, ExnAddr, SelAddr);
354 if (PN->use_empty()) PN->eraseFromParent();
358 I->replaceUsesOfWith(Inst, CreateLandingPadLoad(F, ExnAddr, SelAddr, I));
362 bool SjLjEHPass::insertSjLjEHSupport(Function &F) {
363 SmallVector<ReturnInst*,16> Returns;
364 SmallVector<UnwindInst*,16> Unwinds;
365 SmallVector<InvokeInst*,16> Invokes;
367 // Look through the terminators of the basic blocks to find invokes, returns
369 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
370 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) {
371 // Remember all return instructions in case we insert an invoke into this
373 Returns.push_back(RI);
374 } else if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
375 Invokes.push_back(II);
376 } else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) {
377 Unwinds.push_back(UI);
381 NumInvokes += Invokes.size();
382 NumUnwinds += Unwinds.size();
384 // If we don't have any invokes, there's nothing to do.
385 if (Invokes.empty()) return false;
387 // Find the eh.selector.*, eh.exception and alloca calls.
389 // Remember any allocas() that aren't in the entry block, as the
390 // jmpbuf saved SP will need to be updated for them.
392 // We'll use the first eh.selector to determine the right personality
393 // function to use. For SJLJ, we always use the same personality for the
394 // whole function, not on a per-selector basis.
395 // FIXME: That's a bit ugly. Better way?
396 SmallVector<CallInst*,16> EH_Selectors;
397 SmallVector<CallInst*,16> EH_Exceptions;
398 SmallVector<Instruction*,16> JmpbufUpdatePoints;
400 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
401 // Note: Skip the entry block since there's nothing there that interests
402 // us. eh.selector and eh.exception shouldn't ever be there, and we
403 // want to disregard any allocas that are there.
405 // FIXME: This is awkward. The new EH scheme won't need to skip the entry
407 if (BB == F.begin()) {
408 if (InvokeInst *II = dyn_cast<InvokeInst>(F.begin()->getTerminator())) {
409 // FIXME: This will be always non-NULL in the new EH.
410 if (LandingPadInst *LPI = II->getUnwindDest()->getLandingPadInst())
411 if (!PersonalityFn) PersonalityFn = LPI->getPersonalityFn();
417 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
418 if (CallInst *CI = dyn_cast<CallInst>(I)) {
419 if (CI->getCalledFunction() == SelectorFn) {
420 if (!PersonalityFn) PersonalityFn = CI->getArgOperand(1);
421 EH_Selectors.push_back(CI);
422 } else if (CI->getCalledFunction() == ExceptionFn) {
423 EH_Exceptions.push_back(CI);
424 } else if (CI->getCalledFunction() == StackRestoreFn) {
425 JmpbufUpdatePoints.push_back(CI);
427 } else if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) {
428 JmpbufUpdatePoints.push_back(AI);
429 } else if (InvokeInst *II = dyn_cast<InvokeInst>(I)) {
430 // FIXME: This will be always non-NULL in the new EH.
431 if (LandingPadInst *LPI = II->getUnwindDest()->getLandingPadInst())
432 if (!PersonalityFn) PersonalityFn = LPI->getPersonalityFn();
437 // If we don't have any eh.selector calls, we can't determine the personality
438 // function. Without a personality function, we can't process exceptions.
439 if (!PersonalityFn) return false;
441 // We have invokes, so we need to add register/unregister calls to get this
442 // function onto the global unwind stack.
444 // First thing we need to do is scan the whole function for values that are
445 // live across unwind edges. Each value that is live across an unwind edge we
446 // spill into a stack location, guaranteeing that there is nothing live across
447 // the unwind edge. This process also splits all critical edges coming out of
449 splitLiveRangesAcrossInvokes(Invokes);
452 SmallVector<LandingPadInst*, 16> LandingPads;
453 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
454 if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator()))
455 // FIXME: This will be always non-NULL in the new EH.
456 if (LandingPadInst *LPI = II->getUnwindDest()->getLandingPadInst())
457 LandingPads.push_back(LPI);
461 BasicBlock *EntryBB = F.begin();
462 // Create an alloca for the incoming jump buffer ptr and the new jump buffer
463 // that needs to be restored on all exits from the function. This is an
464 // alloca because the value needs to be added to the global context list.
465 unsigned Align = 4; // FIXME: Should be a TLI check?
466 AllocaInst *FunctionContext =
467 new AllocaInst(FunctionContextTy, 0, Align,
468 "fcn_context", F.begin()->begin());
471 Type *Int32Ty = Type::getInt32Ty(F.getContext());
472 Value *Zero = ConstantInt::get(Int32Ty, 0);
473 // We need to also keep around a reference to the call_site field
475 Idxs[1] = ConstantInt::get(Int32Ty, 1);
476 CallSite = GetElementPtrInst::Create(FunctionContext, Idxs, "call_site",
477 EntryBB->getTerminator());
479 // The exception selector comes back in context->data[1]
480 Idxs[1] = ConstantInt::get(Int32Ty, 2);
481 Value *FCData = GetElementPtrInst::Create(FunctionContext, Idxs, "fc_data",
482 EntryBB->getTerminator());
483 Idxs[1] = ConstantInt::get(Int32Ty, 1);
484 Value *SelectorAddr = GetElementPtrInst::Create(FCData, Idxs,
486 EntryBB->getTerminator());
487 // The exception value comes back in context->data[0]
489 Value *ExceptionAddr = GetElementPtrInst::Create(FCData, Idxs,
491 EntryBB->getTerminator());
493 // The result of the eh.selector call will be replaced with a a reference to
494 // the selector value returned in the function context. We leave the selector
495 // itself so the EH analysis later can use it.
496 for (int i = 0, e = EH_Selectors.size(); i < e; ++i) {
497 CallInst *I = EH_Selectors[i];
498 Value *SelectorVal = new LoadInst(SelectorAddr, "select_val", true, I);
499 I->replaceAllUsesWith(SelectorVal);
502 // eh.exception calls are replaced with references to the proper location in
503 // the context. Unlike eh.selector, the eh.exception calls are removed
505 for (int i = 0, e = EH_Exceptions.size(); i < e; ++i) {
506 CallInst *I = EH_Exceptions[i];
507 // Possible for there to be duplicates, so check to make sure the
508 // instruction hasn't already been removed.
509 if (!I->getParent()) continue;
510 Value *Val = new LoadInst(ExceptionAddr, "exception", true, I);
511 Type *Ty = Type::getInt8PtrTy(F.getContext());
512 Val = CastInst::Create(Instruction::IntToPtr, Val, Ty, "", I);
514 I->replaceAllUsesWith(Val);
515 I->eraseFromParent();
518 for (unsigned i = 0, e = LandingPads.size(); i != e; ++i)
519 ReplaceLandingPadVal(F, LandingPads[i], ExceptionAddr, SelectorAddr);
521 // The entry block changes to have the eh.sjlj.setjmp, with a conditional
522 // branch to a dispatch block for non-zero returns. If we return normally,
523 // we're not handling an exception and just register the function context and
526 // Create the dispatch block. The dispatch block is basically a big switch
527 // statement that goes to all of the invoke landing pads.
528 BasicBlock *DispatchBlock =
529 BasicBlock::Create(F.getContext(), "eh.sjlj.setjmp.catch", &F);
531 // Insert a load of the callsite in the dispatch block, and a switch on its
532 // value. By default, we issue a trap statement.
533 BasicBlock *TrapBlock =
534 BasicBlock::Create(F.getContext(), "trapbb", &F);
535 CallInst::Create(Intrinsic::getDeclaration(F.getParent(), Intrinsic::trap),
537 new UnreachableInst(F.getContext(), TrapBlock);
539 Value *DispatchLoad = new LoadInst(CallSite, "invoke.num", true,
541 SwitchInst *DispatchSwitch =
542 SwitchInst::Create(DispatchLoad, TrapBlock, Invokes.size(),
544 // Split the entry block to insert the conditional branch for the setjmp.
545 BasicBlock *ContBlock = EntryBB->splitBasicBlock(EntryBB->getTerminator(),
546 "eh.sjlj.setjmp.cont");
548 // Populate the Function Context
550 // 2. Personality function address
551 // 3. jmpbuf (save SP, FP and call eh.sjlj.setjmp)
555 Idxs[1] = ConstantInt::get(Int32Ty, 4);
556 Value *LSDAFieldPtr =
557 GetElementPtrInst::Create(FunctionContext, Idxs, "lsda_gep",
558 EntryBB->getTerminator());
559 Value *LSDA = CallInst::Create(LSDAAddrFn, "lsda_addr",
560 EntryBB->getTerminator());
561 new StoreInst(LSDA, LSDAFieldPtr, true, EntryBB->getTerminator());
563 Idxs[1] = ConstantInt::get(Int32Ty, 3);
564 Value *PersonalityFieldPtr =
565 GetElementPtrInst::Create(FunctionContext, Idxs, "lsda_gep",
566 EntryBB->getTerminator());
567 new StoreInst(PersonalityFn, PersonalityFieldPtr, true,
568 EntryBB->getTerminator());
570 // Save the frame pointer.
571 Idxs[1] = ConstantInt::get(Int32Ty, 5);
573 = GetElementPtrInst::Create(FunctionContext, Idxs, "jbuf_gep",
574 EntryBB->getTerminator());
575 Idxs[1] = ConstantInt::get(Int32Ty, 0);
577 GetElementPtrInst::Create(JBufPtr, Idxs, "jbuf_fp_gep",
578 EntryBB->getTerminator());
580 Value *Val = CallInst::Create(FrameAddrFn,
581 ConstantInt::get(Int32Ty, 0),
583 EntryBB->getTerminator());
584 new StoreInst(Val, FramePtr, true, EntryBB->getTerminator());
586 // Save the stack pointer.
587 Idxs[1] = ConstantInt::get(Int32Ty, 2);
589 GetElementPtrInst::Create(JBufPtr, Idxs, "jbuf_sp_gep",
590 EntryBB->getTerminator());
592 Val = CallInst::Create(StackAddrFn, "sp", EntryBB->getTerminator());
593 new StoreInst(Val, StackPtr, true, EntryBB->getTerminator());
595 // Call the setjmp instrinsic. It fills in the rest of the jmpbuf.
597 CastInst::Create(Instruction::BitCast, JBufPtr,
598 Type::getInt8PtrTy(F.getContext()), "",
599 EntryBB->getTerminator());
600 Value *DispatchVal = CallInst::Create(BuiltinSetjmpFn, SetjmpArg,
602 EntryBB->getTerminator());
604 // Add a call to dispatch_setup after the setjmp call. This is expanded to any
605 // target-specific setup that needs to be done.
606 CallInst::Create(DispatchSetupFn, DispatchVal, "", EntryBB->getTerminator());
608 // check the return value of the setjmp. non-zero goes to dispatcher.
609 Value *IsNormal = new ICmpInst(EntryBB->getTerminator(),
610 ICmpInst::ICMP_EQ, DispatchVal, Zero,
612 // Nuke the uncond branch.
613 EntryBB->getTerminator()->eraseFromParent();
615 // Put in a new condbranch in its place.
616 BranchInst::Create(ContBlock, DispatchBlock, IsNormal, EntryBB);
618 // Register the function context and make sure it's known to not throw
620 CallInst::Create(RegisterFn, FunctionContext, "",
621 ContBlock->getTerminator());
622 Register->setDoesNotThrow();
624 // At this point, we are all set up, update the invoke instructions to mark
625 // their call_site values, and fill in the dispatch switch accordingly.
626 for (unsigned i = 0, e = Invokes.size(); i != e; ++i)
627 markInvokeCallSite(Invokes[i], i+1, CallSite, DispatchSwitch);
629 // Mark call instructions that aren't nounwind as no-action (call_site ==
630 // -1). Skip the entry block, as prior to then, no function context has been
631 // created for this function and any unexpected exceptions thrown will go
632 // directly to the caller's context, which is what we want anyway, so no need
633 // to do anything here.
634 for (Function::iterator BB = F.begin(), E = F.end(); ++BB != E;) {
635 for (BasicBlock::iterator I = BB->begin(), end = BB->end(); I != end; ++I)
636 if (CallInst *CI = dyn_cast<CallInst>(I)) {
637 // Ignore calls to the EH builtins (eh.selector, eh.exception)
638 Constant *Callee = CI->getCalledFunction();
639 if (Callee != SelectorFn && Callee != ExceptionFn
640 && !CI->doesNotThrow())
641 insertCallSiteStore(CI, -1, CallSite);
642 } else if (ResumeInst *RI = dyn_cast<ResumeInst>(I)) {
643 insertCallSiteStore(RI, -1, CallSite);
647 // Replace all unwinds with a branch to the unwind handler.
648 // ??? Should this ever happen with sjlj exceptions?
649 for (unsigned i = 0, e = Unwinds.size(); i != e; ++i) {
650 BranchInst::Create(TrapBlock, Unwinds[i]);
651 Unwinds[i]->eraseFromParent();
654 // Following any allocas not in the entry block, update the saved SP in the
655 // jmpbuf to the new value.
656 for (unsigned i = 0, e = JmpbufUpdatePoints.size(); i != e; ++i) {
657 Instruction *AI = JmpbufUpdatePoints[i];
658 Instruction *StackAddr = CallInst::Create(StackAddrFn, "sp");
659 StackAddr->insertAfter(AI);
660 Instruction *StoreStackAddr = new StoreInst(StackAddr, StackPtr, true);
661 StoreStackAddr->insertAfter(StackAddr);
664 // Finally, for any returns from this function, if this function contains an
665 // invoke, add a call to unregister the function context.
666 for (unsigned i = 0, e = Returns.size(); i != e; ++i)
667 CallInst::Create(UnregisterFn, FunctionContext, "", Returns[i]);
672 bool SjLjEHPass::runOnFunction(Function &F) {
673 bool Res = insertSjLjEHSupport(F);