SjLjEHPrepare.cpp revision a235d13217ff14621a88f3ea96a8a3b980c56d02
1//===- SjLjEHPass.cpp - Eliminate Invoke & Unwind instructions -----------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This transformation is designed for use by code generators which use SjLj 11// based exception handling. 12// 13//===----------------------------------------------------------------------===// 14 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/Transforms/Utils/BasicBlockUtils.h" 26#include "llvm/Transforms/Utils/Local.h" 27#include "llvm/ADT/DenseMap.h" 28#include "llvm/ADT/Statistic.h" 29#include "llvm/ADT/SmallVector.h" 30#include "llvm/Support/CommandLine.h" 31#include "llvm/Support/Compiler.h" 32#include "llvm/Support/Debug.h" 33#include "llvm/Support/raw_ostream.h" 34#include "llvm/Target/TargetLowering.h" 35using namespace llvm; 36 37STATISTIC(NumInvokes, "Number of invokes replaced"); 38STATISTIC(NumUnwinds, "Number of unwinds replaced"); 39STATISTIC(NumSpilled, "Number of registers live across unwind edges"); 40 41namespace { 42 class VISIBILITY_HIDDEN SjLjEHPass : public FunctionPass { 43 44 const TargetLowering *TLI; 45 46 const Type *FunctionContextTy; 47 Constant *RegisterFn; 48 Constant *UnregisterFn; 49 Constant *ResumeFn; 50 Constant *BuiltinSetjmpFn; 51 Constant *FrameAddrFn; 52 Constant *LSDAAddrFn; 53 Value *PersonalityFn; 54 Constant *Selector32Fn; 55 Constant *Selector64Fn; 56 Constant *ExceptionFn; 57 58 Value *CallSite; 59 public: 60 static char ID; // Pass identification, replacement for typeid 61 explicit SjLjEHPass(const TargetLowering *tli = NULL) 62 : FunctionPass(&ID), TLI(tli) { } 63 bool doInitialization(Module &M); 64 bool runOnFunction(Function &F); 65 66 virtual void getAnalysisUsage(AnalysisUsage &AU) const { } 67 const char *getPassName() const { 68 return "SJLJ Exception Handling preparation"; 69 } 70 71 private: 72 void markInvokeCallSite(InvokeInst *II, unsigned InvokeNo, 73 Value *CallSite); 74 void splitLiveRangesLiveAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes); 75 bool insertSjLjEHSupport(Function &F); 76 }; 77} // end anonymous namespace 78 79char SjLjEHPass::ID = 0; 80 81// Public Interface To the SjLjEHPass pass. 82FunctionPass *llvm::createSjLjEHPass(const TargetLowering *TLI) { 83 return new SjLjEHPass(TLI); 84} 85// doInitialization - Set up decalarations and types needed to process 86// exceptions. 87bool SjLjEHPass::doInitialization(Module &M) { 88 // Build the function context structure. 89 // builtin_setjmp uses a five word jbuf 90 const Type *VoidPtrTy = 91 PointerType::getUnqual(Type::getInt8Ty(M.getContext())); 92 const Type *Int32Ty = Type::getInt32Ty(M.getContext()); 93 FunctionContextTy = 94 StructType::get(M.getContext(), 95 VoidPtrTy, // __prev 96 Int32Ty, // call_site 97 ArrayType::get(Int32Ty, 4), // __data 98 VoidPtrTy, // __personality 99 VoidPtrTy, // __lsda 100 ArrayType::get(VoidPtrTy, 5), // __jbuf 101 NULL); 102 RegisterFn = M.getOrInsertFunction("_Unwind_SjLj_Register", 103 Type::getVoidTy(M.getContext()), 104 PointerType::getUnqual(FunctionContextTy), 105 (Type *)0); 106 UnregisterFn = 107 M.getOrInsertFunction("_Unwind_SjLj_Unregister", 108 Type::getVoidTy(M.getContext()), 109 PointerType::getUnqual(FunctionContextTy), 110 (Type *)0); 111 ResumeFn = 112 M.getOrInsertFunction("_Unwind_SjLj_Resume", 113 Type::getVoidTy(M.getContext()), 114 VoidPtrTy, 115 (Type *)0); 116 FrameAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::frameaddress); 117 BuiltinSetjmpFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_setjmp); 118 LSDAAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_lsda); 119 Selector32Fn = Intrinsic::getDeclaration(&M, Intrinsic::eh_selector_i32); 120 Selector64Fn = Intrinsic::getDeclaration(&M, Intrinsic::eh_selector_i64); 121 ExceptionFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_exception); 122 PersonalityFn = 0; 123 124 return true; 125} 126 127/// markInvokeCallSite - Insert code to mark the call_site for this invoke 128void SjLjEHPass::markInvokeCallSite(InvokeInst *II, unsigned InvokeNo, 129 Value *CallSite) { 130 ConstantInt *CallSiteNoC= ConstantInt::get(Type::getInt32Ty(II->getContext()), 131 InvokeNo); 132 133 // If the unwind edge has phi nodes, split the edge. 134 if (isa<PHINode>(II->getUnwindDest()->begin())) { 135 SplitCriticalEdge(II, 1, this); 136 137 // If there are any phi nodes left, they must have a single predecessor. 138 while (PHINode *PN = dyn_cast<PHINode>(II->getUnwindDest()->begin())) { 139 PN->replaceAllUsesWith(PN->getIncomingValue(0)); 140 PN->eraseFromParent(); 141 } 142 } 143 144 // Insert a store of the invoke num before the invoke and store zero into the 145 // location afterward. 146 new StoreInst(CallSiteNoC, CallSite, true, II); // volatile 147 148 // We still want this to look like an invoke so we emit the LSDA properly 149 // FIXME: ??? Or will this cause strangeness with mis-matched IDs like 150 // when it was in the front end? 151} 152 153/// MarkBlocksLiveIn - Insert BB and all of its predescessors into LiveBBs until 154/// we reach blocks we've already seen. 155static void MarkBlocksLiveIn(BasicBlock *BB, std::set<BasicBlock*> &LiveBBs) { 156 if (!LiveBBs.insert(BB).second) return; // already been here. 157 158 for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) 159 MarkBlocksLiveIn(*PI, LiveBBs); 160} 161 162/// splitLiveRangesAcrossInvokes - Each value that is live across an unwind edge 163/// we spill into a stack location, guaranteeing that there is nothing live 164/// across the unwind edge. This process also splits all critical edges 165/// coming out of invoke's. 166void SjLjEHPass:: 167splitLiveRangesLiveAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes) { 168 // First step, split all critical edges from invoke instructions. 169 for (unsigned i = 0, e = Invokes.size(); i != e; ++i) { 170 InvokeInst *II = Invokes[i]; 171 SplitCriticalEdge(II, 0, this); 172 SplitCriticalEdge(II, 1, this); 173 assert(!isa<PHINode>(II->getNormalDest()) && 174 !isa<PHINode>(II->getUnwindDest()) && 175 "critical edge splitting left single entry phi nodes?"); 176 } 177 178 Function *F = Invokes.back()->getParent()->getParent(); 179 180 // To avoid having to handle incoming arguments specially, we lower each arg 181 // to a copy instruction in the entry block. This ensures that the argument 182 // value itself cannot be live across the entry block. 183 BasicBlock::iterator AfterAllocaInsertPt = F->begin()->begin(); 184 while (isa<AllocaInst>(AfterAllocaInsertPt) && 185 isa<ConstantInt>(cast<AllocaInst>(AfterAllocaInsertPt)->getArraySize())) 186 ++AfterAllocaInsertPt; 187 for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end(); 188 AI != E; ++AI) { 189 // This is always a no-op cast because we're casting AI to AI->getType() so 190 // src and destination types are identical. BitCast is the only possibility. 191 CastInst *NC = new BitCastInst( 192 AI, AI->getType(), AI->getName()+".tmp", AfterAllocaInsertPt); 193 AI->replaceAllUsesWith(NC); 194 // Normally its is forbidden to replace a CastInst's operand because it 195 // could cause the opcode to reflect an illegal conversion. However, we're 196 // replacing it here with the same value it was constructed with to simply 197 // make NC its user. 198 NC->setOperand(0, AI); 199 } 200 201 // Finally, scan the code looking for instructions with bad live ranges. 202 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) 203 for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ++II) { 204 // Ignore obvious cases we don't have to handle. In particular, most 205 // instructions either have no uses or only have a single use inside the 206 // current block. Ignore them quickly. 207 Instruction *Inst = II; 208 if (Inst->use_empty()) continue; 209 if (Inst->hasOneUse() && 210 cast<Instruction>(Inst->use_back())->getParent() == BB && 211 !isa<PHINode>(Inst->use_back())) continue; 212 213 // If this is an alloca in the entry block, it's not a real register 214 // value. 215 if (AllocaInst *AI = dyn_cast<AllocaInst>(Inst)) 216 if (isa<ConstantInt>(AI->getArraySize()) && BB == F->begin()) 217 continue; 218 219 // Avoid iterator invalidation by copying users to a temporary vector. 220 SmallVector<Instruction*,16> Users; 221 for (Value::use_iterator UI = Inst->use_begin(), E = Inst->use_end(); 222 UI != E; ++UI) { 223 Instruction *User = cast<Instruction>(*UI); 224 if (User->getParent() != BB || isa<PHINode>(User)) 225 Users.push_back(User); 226 } 227 228 // Find all of the blocks that this value is live in. 229 std::set<BasicBlock*> LiveBBs; 230 LiveBBs.insert(Inst->getParent()); 231 while (!Users.empty()) { 232 Instruction *U = Users.back(); 233 Users.pop_back(); 234 235 if (!isa<PHINode>(U)) { 236 MarkBlocksLiveIn(U->getParent(), LiveBBs); 237 } else { 238 // Uses for a PHI node occur in their predecessor block. 239 PHINode *PN = cast<PHINode>(U); 240 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) 241 if (PN->getIncomingValue(i) == Inst) 242 MarkBlocksLiveIn(PN->getIncomingBlock(i), LiveBBs); 243 } 244 } 245 246 // Now that we know all of the blocks that this thing is live in, see if 247 // it includes any of the unwind locations. 248 bool NeedsSpill = false; 249 for (unsigned i = 0, e = Invokes.size(); i != e; ++i) { 250 BasicBlock *UnwindBlock = Invokes[i]->getUnwindDest(); 251 if (UnwindBlock != BB && LiveBBs.count(UnwindBlock)) { 252 NeedsSpill = true; 253 } 254 } 255 256 // If we decided we need a spill, do it. 257 if (NeedsSpill) { 258 ++NumSpilled; 259 DemoteRegToStack(*Inst, true); 260 } 261 } 262} 263 264bool SjLjEHPass::insertSjLjEHSupport(Function &F) { 265 SmallVector<ReturnInst*,16> Returns; 266 SmallVector<UnwindInst*,16> Unwinds; 267 SmallVector<InvokeInst*,16> Invokes; 268 269 // Look through the terminators of the basic blocks to find invokes, returns 270 // and unwinds 271 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) 272 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) { 273 // Remember all return instructions in case we insert an invoke into this 274 // function. 275 Returns.push_back(RI); 276 } else if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) { 277 Invokes.push_back(II); 278 } else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) { 279 Unwinds.push_back(UI); 280 } 281 // If we don't have any invokes or unwinds, there's nothing to do. 282 if (Unwinds.empty() && Invokes.empty()) return false; 283 284 // Find the eh.selector.* and eh.exception calls. We'll use the first 285 // eh.selector to determine the right personality function to use. For 286 // SJLJ, we always use the same personality for the whole function, 287 // not on a per-selector basis. 288 // FIXME: That's a bit ugly. Better way? 289 SmallVector<CallInst*,16> EH_Selectors; 290 SmallVector<CallInst*,16> EH_Exceptions; 291 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) { 292 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) { 293 if (CallInst *CI = dyn_cast<CallInst>(I)) { 294 if (CI->getCalledFunction() == Selector32Fn || 295 CI->getCalledFunction() == Selector64Fn) { 296 if (!PersonalityFn) PersonalityFn = CI->getOperand(2); 297 EH_Selectors.push_back(CI); 298 } else if (CI->getCalledFunction() == ExceptionFn) { 299 EH_Exceptions.push_back(CI); 300 } 301 } 302 } 303 } 304 // If we don't have any eh.selector calls, we can't determine the personality 305 // function. Without a personality function, we can't process exceptions. 306 if (!PersonalityFn) return false; 307 308 NumInvokes += Invokes.size(); 309 NumUnwinds += Unwinds.size(); 310 311 if (!Invokes.empty()) { 312 // We have invokes, so we need to add register/unregister calls to get 313 // this function onto the global unwind stack. 314 315 BasicBlock *EntryBB = F.begin(); 316 // Create an alloca for the incoming jump buffer ptr and the new jump buffer 317 // that needs to be restored on all exits from the function. This is an 318 // alloca because the value needs to be added to the global context list. 319 unsigned Align = 4; // FIXME: Should be a TLI check? 320 AllocaInst *FunctionContext = 321 new AllocaInst(FunctionContextTy, 0, Align, 322 "fcn_context", F.begin()->begin()); 323 324 Value *Idxs[2]; 325 const Type *Int32Ty = Type::getInt32Ty(F.getContext()); 326 Value *Zero = ConstantInt::get(Int32Ty, 0); 327 // We need to also keep around a reference to the call_site field 328 Idxs[0] = Zero; 329 Idxs[1] = ConstantInt::get(Int32Ty, 1); 330 CallSite = GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, 331 "call_site", 332 EntryBB->getTerminator()); 333 334 // The exception selector comes back in context->data[1] 335 Idxs[1] = ConstantInt::get(Int32Ty, 2); 336 Value *FCData = GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, 337 "fc_data", 338 EntryBB->getTerminator()); 339 Idxs[1] = ConstantInt::get(Int32Ty, 1); 340 Value *SelectorAddr = GetElementPtrInst::Create(FCData, Idxs, Idxs+2, 341 "exc_selector_gep", 342 EntryBB->getTerminator()); 343 // The exception value comes back in context->data[0] 344 Idxs[1] = Zero; 345 Value *ExceptionAddr = GetElementPtrInst::Create(FCData, Idxs, Idxs+2, 346 "exception_gep", 347 EntryBB->getTerminator()); 348 349 // The result of the eh.selector call will be replaced with a 350 // a reference to the selector value returned in the function 351 // context. We leave the selector itself so the EH analysis later 352 // can use it. 353 for (int i = 0, e = EH_Selectors.size(); i < e; ++i) { 354 CallInst *I = EH_Selectors[i]; 355 Value *SelectorVal = new LoadInst(SelectorAddr, "select_val", true, I); 356 I->replaceAllUsesWith(SelectorVal); 357 } 358 // eh.exception calls are replaced with references to the proper 359 // location in the context. Unlike eh.selector, the eh.exception 360 // calls are removed entirely. 361 for (int i = 0, e = EH_Exceptions.size(); i < e; ++i) { 362 CallInst *I = EH_Exceptions[i]; 363 // Possible for there to be duplicates, so check to make sure 364 // the instruction hasn't already been removed. 365 if (!I->getParent()) continue; 366 Value *Val = new LoadInst(ExceptionAddr, "exception", true, I); 367 Type *Ty = PointerType::getUnqual(Type::getInt8Ty(F.getContext())); 368 Val = CastInst::Create(Instruction::IntToPtr, Val, Ty, "", I); 369 370 I->replaceAllUsesWith(Val); 371 I->eraseFromParent(); 372 } 373 374 375 376 377 // The entry block changes to have the eh.sjlj.setjmp, with a conditional 378 // branch to a dispatch block for non-zero returns. If we return normally, 379 // we're not handling an exception and just register the function context 380 // and continue. 381 382 // Create the dispatch block. The dispatch block is basically a big switch 383 // statement that goes to all of the invoke landing pads. 384 BasicBlock *DispatchBlock = 385 BasicBlock::Create(F.getContext(), "eh.sjlj.setjmp.catch", &F); 386 387 // Insert a load in the Catch block, and a switch on its value. By default, 388 // we go to a block that just does an unwind (which is the correct action 389 // for a standard call). 390 BasicBlock *UnwindBlock = BasicBlock::Create(F.getContext(), "unwindbb", &F); 391 Unwinds.push_back(new UnwindInst(F.getContext(), UnwindBlock)); 392 393 Value *DispatchLoad = new LoadInst(CallSite, "invoke.num", true, 394 DispatchBlock); 395 SwitchInst *DispatchSwitch = 396 SwitchInst::Create(DispatchLoad, UnwindBlock, Invokes.size(), DispatchBlock); 397 // Split the entry block to insert the conditional branch for the setjmp. 398 BasicBlock *ContBlock = EntryBB->splitBasicBlock(EntryBB->getTerminator(), 399 "eh.sjlj.setjmp.cont"); 400 401 // Populate the Function Context 402 // 1. LSDA address 403 // 2. Personality function address 404 // 3. jmpbuf (save FP and call eh.sjlj.setjmp) 405 406 // LSDA address 407 Idxs[0] = Zero; 408 Idxs[1] = ConstantInt::get(Int32Ty, 4); 409 Value *LSDAFieldPtr = 410 GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, 411 "lsda_gep", 412 EntryBB->getTerminator()); 413 Value *LSDA = CallInst::Create(LSDAAddrFn, "lsda_addr", 414 EntryBB->getTerminator()); 415 new StoreInst(LSDA, LSDAFieldPtr, true, EntryBB->getTerminator()); 416 417 Idxs[1] = ConstantInt::get(Int32Ty, 3); 418 Value *PersonalityFieldPtr = 419 GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, 420 "lsda_gep", 421 EntryBB->getTerminator()); 422 new StoreInst(PersonalityFn, PersonalityFieldPtr, true, 423 EntryBB->getTerminator()); 424 425 // Save the frame pointer. 426 Idxs[1] = ConstantInt::get(Int32Ty, 5); 427 Value *FieldPtr 428 = GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, 429 "jbuf_gep", 430 EntryBB->getTerminator()); 431 Idxs[1] = ConstantInt::get(Int32Ty, 0); 432 Value *ElemPtr = 433 GetElementPtrInst::Create(FieldPtr, Idxs, Idxs+2, "jbuf_fp_gep", 434 EntryBB->getTerminator()); 435 436 Value *Val = CallInst::Create(FrameAddrFn, 437 ConstantInt::get(Int32Ty, 0), 438 "fp", 439 EntryBB->getTerminator()); 440 new StoreInst(Val, ElemPtr, true, EntryBB->getTerminator()); 441 // Call the setjmp instrinsic. It fills in the rest of the jmpbuf 442 Value *SetjmpArg = 443 CastInst::Create(Instruction::BitCast, FieldPtr, 444 Type::getInt8Ty(F.getContext())->getPointerTo(), "", 445 EntryBB->getTerminator()); 446 Value *DispatchVal = CallInst::Create(BuiltinSetjmpFn, SetjmpArg, 447 "dispatch", 448 EntryBB->getTerminator()); 449 // check the return value of the setjmp. non-zero goes to dispatcher 450 Value *IsNormal = new ICmpInst(EntryBB->getTerminator(), 451 ICmpInst::ICMP_EQ, DispatchVal, Zero, 452 "notunwind"); 453 // Nuke the uncond branch. 454 EntryBB->getTerminator()->eraseFromParent(); 455 456 // Put in a new condbranch in its place. 457 BranchInst::Create(ContBlock, DispatchBlock, IsNormal, EntryBB); 458 459 // Register the function context and make sure it's known to not throw 460 CallInst *Register = 461 CallInst::Create(RegisterFn, FunctionContext, "", 462 ContBlock->getTerminator()); 463 Register->setDoesNotThrow(); 464 465 // At this point, we are all set up. Update the invoke instructions 466 // to mark their call_site values, and fill in the dispatch switch 467 // accordingly. 468 DenseMap<BasicBlock*,unsigned> PadSites; 469 unsigned NextCallSiteValue = 1; 470 for (SmallVector<InvokeInst*,16>::iterator I = Invokes.begin(), 471 E = Invokes.end(); I < E; ++I) { 472 unsigned CallSiteValue; 473 BasicBlock *LandingPad = (*I)->getSuccessor(1); 474 // landing pads can be shared. If we see a landing pad again, we 475 // want to make sure to use the same call site index so the dispatch 476 // will go to the right place. 477 CallSiteValue = PadSites[LandingPad]; 478 if (!CallSiteValue) { 479 CallSiteValue = NextCallSiteValue++; 480 PadSites[LandingPad] = CallSiteValue; 481 // Add a switch case to our unwind block. The runtime comes back 482 // to the dispatcher with the call_site - 1 in the context. Odd, 483 // but there it is. 484 ConstantInt *SwitchValC = 485 ConstantInt::get(Type::getInt32Ty((*I)->getContext()), 486 CallSiteValue - 1); 487 DispatchSwitch->addCase(SwitchValC, (*I)->getUnwindDest()); 488 } 489 markInvokeCallSite(*I, CallSiteValue, CallSite); 490 } 491 492 // The front end has likely added calls to _Unwind_Resume. We need 493 // to find those calls and mark the call_site as -1 immediately prior. 494 // resume is a noreturn function, so any block that has a call to it 495 // should end in an 'unreachable' instruction with the call immediately 496 // prior. That's how we'll search. 497 // ??? There's got to be a better way. this is fugly. 498 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) 499 if ((dyn_cast<UnreachableInst>(BB->getTerminator()))) { 500 BasicBlock::iterator I = BB->getTerminator(); 501 // Check the previous instruction and see if it's a resume call 502 if (I == BB->begin()) continue; 503 if (CallInst *CI = dyn_cast<CallInst>(--I)) { 504 if (CI->getCalledFunction() == ResumeFn) { 505 Value *NegativeOne = Constant::getAllOnesValue(Int32Ty); 506 new StoreInst(NegativeOne, CallSite, true, I); // volatile 507 } 508 } 509 } 510 511 // Replace all unwinds with a branch to the unwind handler. 512 // ??? Should this ever happen with sjlj exceptions? 513 for (unsigned i = 0, e = Unwinds.size(); i != e; ++i) { 514 BranchInst::Create(UnwindBlock, Unwinds[i]); 515 Unwinds[i]->eraseFromParent(); 516 } 517 518 // Scan the whole function for values that are live across unwind edges. 519 // Each value that is live across an unwind edge we spill into a stack 520 // location, guaranteeing that there is nothing live across the unwind 521 // edge. This process also splits all critical edges coming out of 522 // invoke's. 523 splitLiveRangesLiveAcrossInvokes(Invokes); 524 525 // Finally, for any returns from this function, if this function contains an 526 // invoke, add a call to unregister the function context. 527 for (unsigned i = 0, e = Returns.size(); i != e; ++i) 528 CallInst::Create(UnregisterFn, FunctionContext, "", Returns[i]); 529 } 530 531 return true; 532} 533 534bool SjLjEHPass::runOnFunction(Function &F) { 535 bool Res = insertSjLjEHSupport(F); 536 return Res; 537} 538