SjLjEHPrepare.cpp revision 06c918d2981b0b470eb4e25642150303264381e8
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/Statistic.h" 28#include "llvm/ADT/SmallVector.h" 29#include "llvm/Support/CommandLine.h" 30#include "llvm/Support/Debug.h" 31#include "llvm/Support/raw_ostream.h" 32#include "llvm/Target/TargetLowering.h" 33using namespace llvm; 34 35STATISTIC(NumInvokes, "Number of invokes replaced"); 36STATISTIC(NumUnwinds, "Number of unwinds replaced"); 37STATISTIC(NumSpilled, "Number of registers live across unwind edges"); 38 39namespace { 40 class SjLjEHPass : public FunctionPass { 41 42 const TargetLowering *TLI; 43 44 const Type *FunctionContextTy; 45 Constant *RegisterFn; 46 Constant *UnregisterFn; 47 Constant *BuiltinSetjmpFn; 48 Constant *FrameAddrFn; 49 Constant *StackAddrFn; 50 Constant *StackRestoreFn; 51 Constant *LSDAAddrFn; 52 Value *PersonalityFn; 53 Constant *SelectorFn; 54 Constant *ExceptionFn; 55 Constant *CallSiteFn; 56 Constant *DispatchSetupFn; 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 insertCallSiteStore(Instruction *I, int Number, Value *CallSite); 73 void markInvokeCallSite(InvokeInst *II, int InvokeNo, Value *CallSite, 74 SwitchInst *CatchSwitch); 75 void splitLiveRangesAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes); 76 bool insertSjLjEHSupport(Function &F); 77 }; 78} // end anonymous namespace 79 80char SjLjEHPass::ID = 0; 81 82// Public Interface To the SjLjEHPass pass. 83FunctionPass *llvm::createSjLjEHPass(const TargetLowering *TLI) { 84 return new SjLjEHPass(TLI); 85} 86// doInitialization - Set up decalarations and types needed to process 87// exceptions. 88bool SjLjEHPass::doInitialization(Module &M) { 89 // Build the function context structure. 90 // builtin_setjmp uses a five word jbuf 91 const Type *VoidPtrTy = 92 Type::getInt8PtrTy(M.getContext()); 93 const Type *Int32Ty = Type::getInt32Ty(M.getContext()); 94 FunctionContextTy = 95 StructType::get(M.getContext(), 96 VoidPtrTy, // __prev 97 Int32Ty, // call_site 98 ArrayType::get(Int32Ty, 4), // __data 99 VoidPtrTy, // __personality 100 VoidPtrTy, // __lsda 101 ArrayType::get(VoidPtrTy, 5), // __jbuf 102 NULL); 103 RegisterFn = M.getOrInsertFunction("_Unwind_SjLj_Register", 104 Type::getVoidTy(M.getContext()), 105 PointerType::getUnqual(FunctionContextTy), 106 (Type *)0); 107 UnregisterFn = 108 M.getOrInsertFunction("_Unwind_SjLj_Unregister", 109 Type::getVoidTy(M.getContext()), 110 PointerType::getUnqual(FunctionContextTy), 111 (Type *)0); 112 FrameAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::frameaddress); 113 StackAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::stacksave); 114 StackRestoreFn = Intrinsic::getDeclaration(&M, Intrinsic::stackrestore); 115 BuiltinSetjmpFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_setjmp); 116 LSDAAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_lsda); 117 SelectorFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_selector); 118 ExceptionFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_exception); 119 CallSiteFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_callsite); 120 DispatchSetupFn 121 = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_dispatch_setup); 122 PersonalityFn = 0; 123 124 return true; 125} 126 127/// insertCallSiteStore - Insert a store of the call-site value to the 128/// function context 129void SjLjEHPass::insertCallSiteStore(Instruction *I, int Number, 130 Value *CallSite) { 131 ConstantInt *CallSiteNoC = ConstantInt::get(Type::getInt32Ty(I->getContext()), 132 Number); 133 // Insert a store of the call-site number 134 new StoreInst(CallSiteNoC, CallSite, true, I); // volatile 135} 136 137/// markInvokeCallSite - Insert code to mark the call_site for this invoke 138void SjLjEHPass::markInvokeCallSite(InvokeInst *II, int InvokeNo, 139 Value *CallSite, 140 SwitchInst *CatchSwitch) { 141 ConstantInt *CallSiteNoC= ConstantInt::get(Type::getInt32Ty(II->getContext()), 142 InvokeNo); 143 // The runtime comes back to the dispatcher with the call_site - 1 in 144 // the context. Odd, but there it is. 145 ConstantInt *SwitchValC = ConstantInt::get(Type::getInt32Ty(II->getContext()), 146 InvokeNo - 1); 147 148 // If the unwind edge has phi nodes, split the edge. 149 if (isa<PHINode>(II->getUnwindDest()->begin())) { 150 SplitCriticalEdge(II, 1, this); 151 152 // If there are any phi nodes left, they must have a single predecessor. 153 while (PHINode *PN = dyn_cast<PHINode>(II->getUnwindDest()->begin())) { 154 PN->replaceAllUsesWith(PN->getIncomingValue(0)); 155 PN->eraseFromParent(); 156 } 157 } 158 159 // Insert the store of the call site value 160 insertCallSiteStore(II, InvokeNo, CallSite); 161 162 // Record the call site value for the back end so it stays associated with 163 // the invoke. 164 CallInst::Create(CallSiteFn, CallSiteNoC, "", II); 165 166 // Add a switch case to our unwind block. 167 CatchSwitch->addCase(SwitchValC, II->getUnwindDest()); 168 // We still want this to look like an invoke so we emit the LSDA properly, 169 // so we don't transform the invoke into a call here. 170} 171 172/// MarkBlocksLiveIn - Insert BB and all of its predescessors into LiveBBs until 173/// we reach blocks we've already seen. 174static void MarkBlocksLiveIn(BasicBlock *BB, std::set<BasicBlock*> &LiveBBs) { 175 if (!LiveBBs.insert(BB).second) return; // already been here. 176 177 for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) 178 MarkBlocksLiveIn(*PI, LiveBBs); 179} 180 181/// splitLiveRangesAcrossInvokes - Each value that is live across an unwind edge 182/// we spill into a stack location, guaranteeing that there is nothing live 183/// across the unwind edge. This process also splits all critical edges 184/// coming out of invoke's. 185/// FIXME: Move this function to a common utility file (Local.cpp?) so 186/// both SjLj and LowerInvoke can use it. 187void SjLjEHPass:: 188splitLiveRangesAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes) { 189 // First step, split all critical edges from invoke instructions. 190 for (unsigned i = 0, e = Invokes.size(); i != e; ++i) { 191 InvokeInst *II = Invokes[i]; 192 SplitCriticalEdge(II, 0, this); 193 SplitCriticalEdge(II, 1, this); 194 assert(!isa<PHINode>(II->getNormalDest()) && 195 !isa<PHINode>(II->getUnwindDest()) && 196 "critical edge splitting left single entry phi nodes?"); 197 } 198 199 Function *F = Invokes.back()->getParent()->getParent(); 200 201 // To avoid having to handle incoming arguments specially, we lower each arg 202 // to a copy instruction in the entry block. This ensures that the argument 203 // value itself cannot be live across the entry block. 204 BasicBlock::iterator AfterAllocaInsertPt = F->begin()->begin(); 205 while (isa<AllocaInst>(AfterAllocaInsertPt) && 206 isa<ConstantInt>(cast<AllocaInst>(AfterAllocaInsertPt)->getArraySize())) 207 ++AfterAllocaInsertPt; 208 for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end(); 209 AI != E; ++AI) { 210 const Type *Ty = AI->getType(); 211 // Aggregate types can't be cast, but are legal argument types, so we have 212 // to handle them differently. We use an extract/insert pair as a 213 // lightweight method to achieve the same goal. 214 if (isa<StructType>(Ty) || isa<ArrayType>(Ty) || isa<VectorType>(Ty)) { 215 Instruction *EI = ExtractValueInst::Create(AI, 0, "",AfterAllocaInsertPt); 216 Instruction *NI = InsertValueInst::Create(AI, EI, 0); 217 NI->insertAfter(EI); 218 AI->replaceAllUsesWith(NI); 219 // Set the operand of the instructions back to the AllocaInst. 220 EI->setOperand(0, AI); 221 NI->setOperand(0, AI); 222 } else { 223 // This is always a no-op cast because we're casting AI to AI->getType() 224 // so src and destination types are identical. BitCast is the only 225 // possibility. 226 CastInst *NC = new BitCastInst( 227 AI, AI->getType(), AI->getName()+".tmp", AfterAllocaInsertPt); 228 AI->replaceAllUsesWith(NC); 229 // Set the operand of the cast instruction back to the AllocaInst. 230 // Normally it's forbidden to replace a CastInst's operand because it 231 // could cause the opcode to reflect an illegal conversion. However, 232 // we're replacing it here with the same value it was constructed with. 233 // We do this because the above replaceAllUsesWith() clobbered the 234 // operand, but we want this one to remain. 235 NC->setOperand(0, AI); 236 } 237 } 238 239 // Finally, scan the code looking for instructions with bad live ranges. 240 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) 241 for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ++II) { 242 // Ignore obvious cases we don't have to handle. In particular, most 243 // instructions either have no uses or only have a single use inside the 244 // current block. Ignore them quickly. 245 Instruction *Inst = II; 246 if (Inst->use_empty()) continue; 247 if (Inst->hasOneUse() && 248 cast<Instruction>(Inst->use_back())->getParent() == BB && 249 !isa<PHINode>(Inst->use_back())) continue; 250 251 // If this is an alloca in the entry block, it's not a real register 252 // value. 253 if (AllocaInst *AI = dyn_cast<AllocaInst>(Inst)) 254 if (isa<ConstantInt>(AI->getArraySize()) && BB == F->begin()) 255 continue; 256 257 // Avoid iterator invalidation by copying users to a temporary vector. 258 SmallVector<Instruction*,16> Users; 259 for (Value::use_iterator UI = Inst->use_begin(), E = Inst->use_end(); 260 UI != E; ++UI) { 261 Instruction *User = cast<Instruction>(*UI); 262 if (User->getParent() != BB || isa<PHINode>(User)) 263 Users.push_back(User); 264 } 265 266 // Find all of the blocks that this value is live in. 267 std::set<BasicBlock*> LiveBBs; 268 LiveBBs.insert(Inst->getParent()); 269 while (!Users.empty()) { 270 Instruction *U = Users.back(); 271 Users.pop_back(); 272 273 if (!isa<PHINode>(U)) { 274 MarkBlocksLiveIn(U->getParent(), LiveBBs); 275 } else { 276 // Uses for a PHI node occur in their predecessor block. 277 PHINode *PN = cast<PHINode>(U); 278 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) 279 if (PN->getIncomingValue(i) == Inst) 280 MarkBlocksLiveIn(PN->getIncomingBlock(i), LiveBBs); 281 } 282 } 283 284 // Now that we know all of the blocks that this thing is live in, see if 285 // it includes any of the unwind locations. 286 bool NeedsSpill = false; 287 for (unsigned i = 0, e = Invokes.size(); i != e; ++i) { 288 BasicBlock *UnwindBlock = Invokes[i]->getUnwindDest(); 289 if (UnwindBlock != BB && LiveBBs.count(UnwindBlock)) { 290 NeedsSpill = true; 291 } 292 } 293 294 // If we decided we need a spill, do it. 295 // FIXME: Spilling this way is overkill, as it forces all uses of 296 // the value to be reloaded from the stack slot, even those that aren't 297 // in the unwind blocks. We should be more selective. 298 if (NeedsSpill) { 299 ++NumSpilled; 300 DemoteRegToStack(*Inst, true); 301 } 302 } 303} 304 305bool SjLjEHPass::insertSjLjEHSupport(Function &F) { 306 SmallVector<ReturnInst*,16> Returns; 307 SmallVector<UnwindInst*,16> Unwinds; 308 SmallVector<InvokeInst*,16> Invokes; 309 310 // Look through the terminators of the basic blocks to find invokes, returns 311 // and unwinds. 312 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) { 313 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) { 314 // Remember all return instructions in case we insert an invoke into this 315 // function. 316 Returns.push_back(RI); 317 } else if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) { 318 Invokes.push_back(II); 319 } else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) { 320 Unwinds.push_back(UI); 321 } 322 } 323 // If we don't have any invokes or unwinds, there's nothing to do. 324 if (Unwinds.empty() && Invokes.empty()) return false; 325 326 // Find the eh.selector.*, eh.exception and alloca calls. 327 // 328 // Remember any allocas() that aren't in the entry block, as the 329 // jmpbuf saved SP will need to be updated for them. 330 // 331 // We'll use the first eh.selector to determine the right personality 332 // function to use. For SJLJ, we always use the same personality for the 333 // whole function, not on a per-selector basis. 334 // FIXME: That's a bit ugly. Better way? 335 SmallVector<CallInst*,16> EH_Selectors; 336 SmallVector<CallInst*,16> EH_Exceptions; 337 SmallVector<Instruction*,16> JmpbufUpdatePoints; 338 // Note: Skip the entry block since there's nothing there that interests 339 // us. eh.selector and eh.exception shouldn't ever be there, and we 340 // want to disregard any allocas that are there. 341 for (Function::iterator BB = F.begin(), E = F.end(); ++BB != E;) { 342 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) { 343 if (CallInst *CI = dyn_cast<CallInst>(I)) { 344 if (CI->getCalledFunction() == SelectorFn) { 345 if (!PersonalityFn) PersonalityFn = CI->getArgOperand(1); 346 EH_Selectors.push_back(CI); 347 } else if (CI->getCalledFunction() == ExceptionFn) { 348 EH_Exceptions.push_back(CI); 349 } else if (CI->getCalledFunction() == StackRestoreFn) { 350 JmpbufUpdatePoints.push_back(CI); 351 } 352 } else if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) { 353 JmpbufUpdatePoints.push_back(AI); 354 } 355 } 356 } 357 // If we don't have any eh.selector calls, we can't determine the personality 358 // function. Without a personality function, we can't process exceptions. 359 if (!PersonalityFn) return false; 360 361 NumInvokes += Invokes.size(); 362 NumUnwinds += Unwinds.size(); 363 364 if (!Invokes.empty()) { 365 // We have invokes, so we need to add register/unregister calls to get 366 // this function onto the global unwind stack. 367 // 368 // First thing we need to do is scan the whole function for values that are 369 // live across unwind edges. Each value that is live across an unwind edge 370 // we spill into a stack location, guaranteeing that there is nothing live 371 // across the unwind edge. This process also splits all critical edges 372 // coming out of invoke's. 373 splitLiveRangesAcrossInvokes(Invokes); 374 375 BasicBlock *EntryBB = F.begin(); 376 // Create an alloca for the incoming jump buffer ptr and the new jump buffer 377 // that needs to be restored on all exits from the function. This is an 378 // alloca because the value needs to be added to the global context list. 379 unsigned Align = 4; // FIXME: Should be a TLI check? 380 AllocaInst *FunctionContext = 381 new AllocaInst(FunctionContextTy, 0, Align, 382 "fcn_context", F.begin()->begin()); 383 384 Value *Idxs[2]; 385 const Type *Int32Ty = Type::getInt32Ty(F.getContext()); 386 Value *Zero = ConstantInt::get(Int32Ty, 0); 387 // We need to also keep around a reference to the call_site field 388 Idxs[0] = Zero; 389 Idxs[1] = ConstantInt::get(Int32Ty, 1); 390 CallSite = GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, 391 "call_site", 392 EntryBB->getTerminator()); 393 394 // The exception selector comes back in context->data[1] 395 Idxs[1] = ConstantInt::get(Int32Ty, 2); 396 Value *FCData = GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, 397 "fc_data", 398 EntryBB->getTerminator()); 399 Idxs[1] = ConstantInt::get(Int32Ty, 1); 400 Value *SelectorAddr = GetElementPtrInst::Create(FCData, Idxs, Idxs+2, 401 "exc_selector_gep", 402 EntryBB->getTerminator()); 403 // The exception value comes back in context->data[0] 404 Idxs[1] = Zero; 405 Value *ExceptionAddr = GetElementPtrInst::Create(FCData, Idxs, Idxs+2, 406 "exception_gep", 407 EntryBB->getTerminator()); 408 409 // The result of the eh.selector call will be replaced with a 410 // a reference to the selector value returned in the function 411 // context. We leave the selector itself so the EH analysis later 412 // can use it. 413 for (int i = 0, e = EH_Selectors.size(); i < e; ++i) { 414 CallInst *I = EH_Selectors[i]; 415 Value *SelectorVal = new LoadInst(SelectorAddr, "select_val", true, I); 416 I->replaceAllUsesWith(SelectorVal); 417 } 418 // eh.exception calls are replaced with references to the proper 419 // location in the context. Unlike eh.selector, the eh.exception 420 // calls are removed entirely. 421 for (int i = 0, e = EH_Exceptions.size(); i < e; ++i) { 422 CallInst *I = EH_Exceptions[i]; 423 // Possible for there to be duplicates, so check to make sure 424 // the instruction hasn't already been removed. 425 if (!I->getParent()) continue; 426 Value *Val = new LoadInst(ExceptionAddr, "exception", true, I); 427 const Type *Ty = Type::getInt8PtrTy(F.getContext()); 428 Val = CastInst::Create(Instruction::IntToPtr, Val, Ty, "", I); 429 430 I->replaceAllUsesWith(Val); 431 I->eraseFromParent(); 432 } 433 434 // The entry block changes to have the eh.sjlj.setjmp, with a conditional 435 // branch to a dispatch block for non-zero returns. If we return normally, 436 // we're not handling an exception and just register the function context 437 // and continue. 438 439 // Create the dispatch block. The dispatch block is basically a big switch 440 // statement that goes to all of the invoke landing pads. 441 BasicBlock *DispatchBlock = 442 BasicBlock::Create(F.getContext(), "eh.sjlj.setjmp.catch", &F); 443 444 // Add a call to dispatch_setup at the start of the dispatch block. This 445 // is expanded to any target-specific setup that needs to be done. 446 Value *SetupArg = 447 CastInst::Create(Instruction::BitCast, FunctionContext, 448 Type::getInt8PtrTy(F.getContext()), "", 449 DispatchBlock); 450 CallInst::Create(DispatchSetupFn, SetupArg, "", DispatchBlock); 451 452 // Insert a load of the callsite in the dispatch block, and a switch on 453 // its value. By default, we go to a block that just does an unwind 454 // (which is the correct action for a standard call). 455 BasicBlock *UnwindBlock = 456 BasicBlock::Create(F.getContext(), "unwindbb", &F); 457 Unwinds.push_back(new UnwindInst(F.getContext(), UnwindBlock)); 458 459 Value *DispatchLoad = new LoadInst(CallSite, "invoke.num", true, 460 DispatchBlock); 461 SwitchInst *DispatchSwitch = 462 SwitchInst::Create(DispatchLoad, UnwindBlock, Invokes.size(), 463 DispatchBlock); 464 // Split the entry block to insert the conditional branch for the setjmp. 465 BasicBlock *ContBlock = EntryBB->splitBasicBlock(EntryBB->getTerminator(), 466 "eh.sjlj.setjmp.cont"); 467 468 // Populate the Function Context 469 // 1. LSDA address 470 // 2. Personality function address 471 // 3. jmpbuf (save SP, FP and call eh.sjlj.setjmp) 472 473 // LSDA address 474 Idxs[0] = Zero; 475 Idxs[1] = ConstantInt::get(Int32Ty, 4); 476 Value *LSDAFieldPtr = 477 GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, 478 "lsda_gep", 479 EntryBB->getTerminator()); 480 Value *LSDA = CallInst::Create(LSDAAddrFn, "lsda_addr", 481 EntryBB->getTerminator()); 482 new StoreInst(LSDA, LSDAFieldPtr, true, EntryBB->getTerminator()); 483 484 Idxs[1] = ConstantInt::get(Int32Ty, 3); 485 Value *PersonalityFieldPtr = 486 GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, 487 "lsda_gep", 488 EntryBB->getTerminator()); 489 new StoreInst(PersonalityFn, PersonalityFieldPtr, true, 490 EntryBB->getTerminator()); 491 492 // Save the frame pointer. 493 Idxs[1] = ConstantInt::get(Int32Ty, 5); 494 Value *JBufPtr 495 = GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, 496 "jbuf_gep", 497 EntryBB->getTerminator()); 498 Idxs[1] = ConstantInt::get(Int32Ty, 0); 499 Value *FramePtr = 500 GetElementPtrInst::Create(JBufPtr, Idxs, Idxs+2, "jbuf_fp_gep", 501 EntryBB->getTerminator()); 502 503 Value *Val = CallInst::Create(FrameAddrFn, 504 ConstantInt::get(Int32Ty, 0), 505 "fp", 506 EntryBB->getTerminator()); 507 new StoreInst(Val, FramePtr, true, EntryBB->getTerminator()); 508 509 // Save the stack pointer. 510 Idxs[1] = ConstantInt::get(Int32Ty, 2); 511 Value *StackPtr = 512 GetElementPtrInst::Create(JBufPtr, Idxs, Idxs+2, "jbuf_sp_gep", 513 EntryBB->getTerminator()); 514 515 Val = CallInst::Create(StackAddrFn, "sp", EntryBB->getTerminator()); 516 new StoreInst(Val, StackPtr, true, EntryBB->getTerminator()); 517 518 // Call the setjmp instrinsic. It fills in the rest of the jmpbuf. 519 Value *SetjmpArg = 520 CastInst::Create(Instruction::BitCast, JBufPtr, 521 Type::getInt8PtrTy(F.getContext()), "", 522 EntryBB->getTerminator()); 523 Value *DispatchVal = CallInst::Create(BuiltinSetjmpFn, SetjmpArg, 524 "dispatch", 525 EntryBB->getTerminator()); 526 // check the return value of the setjmp. non-zero goes to dispatcher. 527 Value *IsNormal = new ICmpInst(EntryBB->getTerminator(), 528 ICmpInst::ICMP_EQ, DispatchVal, Zero, 529 "notunwind"); 530 // Nuke the uncond branch. 531 EntryBB->getTerminator()->eraseFromParent(); 532 533 // Put in a new condbranch in its place. 534 BranchInst::Create(ContBlock, DispatchBlock, IsNormal, EntryBB); 535 536 // Register the function context and make sure it's known to not throw 537 CallInst *Register = 538 CallInst::Create(RegisterFn, FunctionContext, "", 539 ContBlock->getTerminator()); 540 Register->setDoesNotThrow(); 541 542 // At this point, we are all set up, update the invoke instructions 543 // to mark their call_site values, and fill in the dispatch switch 544 // accordingly. 545 for (unsigned i = 0, e = Invokes.size(); i != e; ++i) 546 markInvokeCallSite(Invokes[i], i+1, CallSite, DispatchSwitch); 547 548 // Mark call instructions that aren't nounwind as no-action 549 // (call_site == -1). Skip the entry block, as prior to then, no function 550 // context has been created for this function and any unexpected exceptions 551 // thrown will go directly to the caller's context, which is what we want 552 // anyway, so no need to do anything here. 553 for (Function::iterator BB = F.begin(), E = F.end(); ++BB != E;) { 554 for (BasicBlock::iterator I = BB->begin(), end = BB->end(); I != end; ++I) 555 if (CallInst *CI = dyn_cast<CallInst>(I)) { 556 // Ignore calls to the EH builtins (eh.selector, eh.exception) 557 Constant *Callee = CI->getCalledFunction(); 558 if (Callee != SelectorFn && Callee != ExceptionFn 559 && !CI->doesNotThrow()) 560 insertCallSiteStore(CI, -1, CallSite); 561 } 562 } 563 564 // Replace all unwinds with a branch to the unwind handler. 565 // ??? Should this ever happen with sjlj exceptions? 566 for (unsigned i = 0, e = Unwinds.size(); i != e; ++i) { 567 BranchInst::Create(UnwindBlock, Unwinds[i]); 568 Unwinds[i]->eraseFromParent(); 569 } 570 571 // Following any allocas not in the entry block, update the saved SP 572 // in the jmpbuf to the new value. 573 for (unsigned i = 0, e = JmpbufUpdatePoints.size(); i != e; ++i) { 574 Instruction *AI = JmpbufUpdatePoints[i]; 575 Instruction *StackAddr = CallInst::Create(StackAddrFn, "sp"); 576 StackAddr->insertAfter(AI); 577 Instruction *StoreStackAddr = new StoreInst(StackAddr, StackPtr, true); 578 StoreStackAddr->insertAfter(StackAddr); 579 } 580 581 // Finally, for any returns from this function, if this function contains an 582 // invoke, add a call to unregister the function context. 583 for (unsigned i = 0, e = Returns.size(); i != e; ++i) 584 CallInst::Create(UnregisterFn, FunctionContext, "", Returns[i]); 585 } 586 587 return true; 588} 589 590bool SjLjEHPass::runOnFunction(Function &F) { 591 bool Res = insertSjLjEHSupport(F); 592 return Res; 593} 594