SjLjEHPrepare.cpp revision 6c1547368f10302df81ea55ede12db645284f872
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 57 Value *CallSite; 58 public: 59 static char ID; // Pass identification, replacement for typeid 60 explicit SjLjEHPass(const TargetLowering *tli = NULL) 61 : FunctionPass(&ID), TLI(tli) { } 62 bool doInitialization(Module &M); 63 bool runOnFunction(Function &F); 64 65 virtual void getAnalysisUsage(AnalysisUsage &AU) const { } 66 const char *getPassName() const { 67 return "SJLJ Exception Handling preparation"; 68 } 69 70 private: 71 void insertCallSiteStore(Instruction *I, int Number, Value *CallSite); 72 void markInvokeCallSite(InvokeInst *II, int InvokeNo, Value *CallSite, 73 SwitchInst *CatchSwitch); 74 void splitLiveRangesAcrossInvokes(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 Type::getInt8PtrTy(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 FrameAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::frameaddress); 112 StackAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::stacksave); 113 StackRestoreFn = Intrinsic::getDeclaration(&M, Intrinsic::stackrestore); 114 BuiltinSetjmpFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_setjmp); 115 LSDAAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_lsda); 116 SelectorFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_selector); 117 ExceptionFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_exception); 118 CallSiteFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_callsite); 119 PersonalityFn = 0; 120 121 return true; 122} 123 124/// insertCallSiteStore - Insert a store of the call-site value to the 125/// function context 126void SjLjEHPass::insertCallSiteStore(Instruction *I, int Number, 127 Value *CallSite) { 128 ConstantInt *CallSiteNoC = ConstantInt::get(Type::getInt32Ty(I->getContext()), 129 Number); 130 // Insert a store of the call-site number 131 new StoreInst(CallSiteNoC, CallSite, true, I); // volatile 132} 133 134/// markInvokeCallSite - Insert code to mark the call_site for this invoke 135void SjLjEHPass::markInvokeCallSite(InvokeInst *II, int InvokeNo, 136 Value *CallSite, 137 SwitchInst *CatchSwitch) { 138 ConstantInt *CallSiteNoC= ConstantInt::get(Type::getInt32Ty(II->getContext()), 139 InvokeNo); 140 // The runtime comes back to the dispatcher with the call_site - 1 in 141 // the context. Odd, but there it is. 142 ConstantInt *SwitchValC = ConstantInt::get(Type::getInt32Ty(II->getContext()), 143 InvokeNo - 1); 144 145 // If the unwind edge has phi nodes, split the edge. 146 if (isa<PHINode>(II->getUnwindDest()->begin())) { 147 SplitCriticalEdge(II, 1, this); 148 149 // If there are any phi nodes left, they must have a single predecessor. 150 while (PHINode *PN = dyn_cast<PHINode>(II->getUnwindDest()->begin())) { 151 PN->replaceAllUsesWith(PN->getIncomingValue(0)); 152 PN->eraseFromParent(); 153 } 154 } 155 156 // Insert the store of the call site value 157 insertCallSiteStore(II, InvokeNo, CallSite); 158 159 // Record the call site value for the back end so it stays associated with 160 // the invoke. 161 CallInst::Create(CallSiteFn, CallSiteNoC, "", II); 162 163 // Add a switch case to our unwind block. 164 CatchSwitch->addCase(SwitchValC, II->getUnwindDest()); 165 // We still want this to look like an invoke so we emit the LSDA properly, 166 // so we don't transform the invoke into a call here. 167} 168 169/// MarkBlocksLiveIn - Insert BB and all of its predescessors into LiveBBs until 170/// we reach blocks we've already seen. 171static void MarkBlocksLiveIn(BasicBlock *BB, std::set<BasicBlock*> &LiveBBs) { 172 if (!LiveBBs.insert(BB).second) return; // already been here. 173 174 for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) 175 MarkBlocksLiveIn(*PI, LiveBBs); 176} 177 178/// splitLiveRangesAcrossInvokes - Each value that is live across an unwind edge 179/// we spill into a stack location, guaranteeing that there is nothing live 180/// across the unwind edge. This process also splits all critical edges 181/// coming out of invoke's. 182/// FIXME: Move this function to a common utility file (Local.cpp?) so 183/// both SjLj and LowerInvoke can use it. 184void SjLjEHPass:: 185splitLiveRangesAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes) { 186 // First step, split all critical edges from invoke instructions. 187 for (unsigned i = 0, e = Invokes.size(); i != e; ++i) { 188 InvokeInst *II = Invokes[i]; 189 SplitCriticalEdge(II, 0, this); 190 SplitCriticalEdge(II, 1, this); 191 assert(!isa<PHINode>(II->getNormalDest()) && 192 !isa<PHINode>(II->getUnwindDest()) && 193 "critical edge splitting left single entry phi nodes?"); 194 } 195 196 Function *F = Invokes.back()->getParent()->getParent(); 197 198 // To avoid having to handle incoming arguments specially, we lower each arg 199 // to a copy instruction in the entry block. This ensures that the argument 200 // value itself cannot be live across the entry block. 201 BasicBlock::iterator AfterAllocaInsertPt = F->begin()->begin(); 202 while (isa<AllocaInst>(AfterAllocaInsertPt) && 203 isa<ConstantInt>(cast<AllocaInst>(AfterAllocaInsertPt)->getArraySize())) 204 ++AfterAllocaInsertPt; 205 for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end(); 206 AI != E; ++AI) { 207 const Type *Ty = AI->getType(); 208 // Aggregate types can't be cast, but are legal argument types, so we have 209 // to handle them differently. We use an extract/insert pair as a 210 // lightweight method to achieve the same goal. 211 if (isa<StructType>(Ty) || isa<ArrayType>(Ty) || isa<VectorType>(Ty)) { 212 Instruction *EI = ExtractValueInst::Create(AI, 0, "",AfterAllocaInsertPt); 213 Instruction *NI = InsertValueInst::Create(AI, EI, 0); 214 NI->insertAfter(EI); 215 AI->replaceAllUsesWith(NI); 216 // Set the operand of the instructions back to the AllocaInst. 217 EI->setOperand(0, AI); 218 NI->setOperand(0, AI); 219 } else { 220 // This is always a no-op cast because we're casting AI to AI->getType() 221 // so src and destination types are identical. BitCast is the only 222 // possibility. 223 CastInst *NC = new BitCastInst( 224 AI, AI->getType(), AI->getName()+".tmp", AfterAllocaInsertPt); 225 AI->replaceAllUsesWith(NC); 226 // Set the operand of the cast instruction back to the AllocaInst. 227 // Normally it's forbidden to replace a CastInst's operand because it 228 // could cause the opcode to reflect an illegal conversion. However, 229 // we're replacing it here with the same value it was constructed with. 230 // We do this because the above replaceAllUsesWith() clobbered the 231 // operand, but we want this one to remain. 232 NC->setOperand(0, AI); 233 } 234 } 235 236 // Finally, scan the code looking for instructions with bad live ranges. 237 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) 238 for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ++II) { 239 // Ignore obvious cases we don't have to handle. In particular, most 240 // instructions either have no uses or only have a single use inside the 241 // current block. Ignore them quickly. 242 Instruction *Inst = II; 243 if (Inst->use_empty()) continue; 244 if (Inst->hasOneUse() && 245 cast<Instruction>(Inst->use_back())->getParent() == BB && 246 !isa<PHINode>(Inst->use_back())) continue; 247 248 // If this is an alloca in the entry block, it's not a real register 249 // value. 250 if (AllocaInst *AI = dyn_cast<AllocaInst>(Inst)) 251 if (isa<ConstantInt>(AI->getArraySize()) && BB == F->begin()) 252 continue; 253 254 // Avoid iterator invalidation by copying users to a temporary vector. 255 SmallVector<Instruction*,16> Users; 256 for (Value::use_iterator UI = Inst->use_begin(), E = Inst->use_end(); 257 UI != E; ++UI) { 258 Instruction *User = cast<Instruction>(*UI); 259 if (User->getParent() != BB || isa<PHINode>(User)) 260 Users.push_back(User); 261 } 262 263 // Find all of the blocks that this value is live in. 264 std::set<BasicBlock*> LiveBBs; 265 LiveBBs.insert(Inst->getParent()); 266 while (!Users.empty()) { 267 Instruction *U = Users.back(); 268 Users.pop_back(); 269 270 if (!isa<PHINode>(U)) { 271 MarkBlocksLiveIn(U->getParent(), LiveBBs); 272 } else { 273 // Uses for a PHI node occur in their predecessor block. 274 PHINode *PN = cast<PHINode>(U); 275 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) 276 if (PN->getIncomingValue(i) == Inst) 277 MarkBlocksLiveIn(PN->getIncomingBlock(i), LiveBBs); 278 } 279 } 280 281 // Now that we know all of the blocks that this thing is live in, see if 282 // it includes any of the unwind locations. 283 bool NeedsSpill = false; 284 for (unsigned i = 0, e = Invokes.size(); i != e; ++i) { 285 BasicBlock *UnwindBlock = Invokes[i]->getUnwindDest(); 286 if (UnwindBlock != BB && LiveBBs.count(UnwindBlock)) { 287 NeedsSpill = true; 288 } 289 } 290 291 // If we decided we need a spill, do it. 292 // FIXME: Spilling this way is overkill, as it forces all uses of 293 // the value to be reloaded from the stack slot, even those that aren't 294 // in the unwind blocks. We should be more selective. 295 if (NeedsSpill) { 296 ++NumSpilled; 297 DemoteRegToStack(*Inst, true); 298 } 299 } 300} 301 302bool SjLjEHPass::insertSjLjEHSupport(Function &F) { 303 SmallVector<ReturnInst*,16> Returns; 304 SmallVector<UnwindInst*,16> Unwinds; 305 SmallVector<InvokeInst*,16> Invokes; 306 307 // Look through the terminators of the basic blocks to find invokes, returns 308 // and unwinds. 309 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) { 310 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) { 311 // Remember all return instructions in case we insert an invoke into this 312 // function. 313 Returns.push_back(RI); 314 } else if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) { 315 Invokes.push_back(II); 316 } else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) { 317 Unwinds.push_back(UI); 318 } 319 } 320 // If we don't have any invokes or unwinds, there's nothing to do. 321 if (Unwinds.empty() && Invokes.empty()) return false; 322 323 // Find the eh.selector.*, eh.exception and alloca calls. 324 // 325 // Remember any allocas() that aren't in the entry block, as the 326 // jmpbuf saved SP will need to be updated for them. 327 // 328 // We'll use the first eh.selector to determine the right personality 329 // function to use. For SJLJ, we always use the same personality for the 330 // whole function, not on a per-selector basis. 331 // FIXME: That's a bit ugly. Better way? 332 SmallVector<CallInst*,16> EH_Selectors; 333 SmallVector<CallInst*,16> EH_Exceptions; 334 SmallVector<Instruction*,16> JmpbufUpdatePoints; 335 // Note: Skip the entry block since there's nothing there that interests 336 // us. eh.selector and eh.exception shouldn't ever be there, and we 337 // want to disregard any allocas that are there. 338 for (Function::iterator BB = F.begin(), E = F.end(); ++BB != E;) { 339 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) { 340 if (CallInst *CI = dyn_cast<CallInst>(I)) { 341 if (CI->getCalledFunction() == SelectorFn) { 342 if (!PersonalityFn) PersonalityFn = CI->getArgOperand(1); 343 EH_Selectors.push_back(CI); 344 } else if (CI->getCalledFunction() == ExceptionFn) { 345 EH_Exceptions.push_back(CI); 346 } else if (CI->getCalledFunction() == StackRestoreFn) { 347 JmpbufUpdatePoints.push_back(CI); 348 } 349 } else if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) { 350 JmpbufUpdatePoints.push_back(AI); 351 } 352 } 353 } 354 // If we don't have any eh.selector calls, we can't determine the personality 355 // function. Without a personality function, we can't process exceptions. 356 if (!PersonalityFn) return false; 357 358 NumInvokes += Invokes.size(); 359 NumUnwinds += Unwinds.size(); 360 361 if (!Invokes.empty()) { 362 // We have invokes, so we need to add register/unregister calls to get 363 // this function onto the global unwind stack. 364 // 365 // First thing we need to do is scan the whole function for values that are 366 // live across unwind edges. Each value that is live across an unwind edge 367 // we spill into a stack location, guaranteeing that there is nothing live 368 // across the unwind edge. This process also splits all critical edges 369 // coming out of invoke's. 370 splitLiveRangesAcrossInvokes(Invokes); 371 372 BasicBlock *EntryBB = F.begin(); 373 // Create an alloca for the incoming jump buffer ptr and the new jump buffer 374 // that needs to be restored on all exits from the function. This is an 375 // alloca because the value needs to be added to the global context list. 376 unsigned Align = 4; // FIXME: Should be a TLI check? 377 AllocaInst *FunctionContext = 378 new AllocaInst(FunctionContextTy, 0, Align, 379 "fcn_context", F.begin()->begin()); 380 381 Value *Idxs[2]; 382 const Type *Int32Ty = Type::getInt32Ty(F.getContext()); 383 Value *Zero = ConstantInt::get(Int32Ty, 0); 384 // We need to also keep around a reference to the call_site field 385 Idxs[0] = Zero; 386 Idxs[1] = ConstantInt::get(Int32Ty, 1); 387 CallSite = GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, 388 "call_site", 389 EntryBB->getTerminator()); 390 391 // The exception selector comes back in context->data[1] 392 Idxs[1] = ConstantInt::get(Int32Ty, 2); 393 Value *FCData = GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, 394 "fc_data", 395 EntryBB->getTerminator()); 396 Idxs[1] = ConstantInt::get(Int32Ty, 1); 397 Value *SelectorAddr = GetElementPtrInst::Create(FCData, Idxs, Idxs+2, 398 "exc_selector_gep", 399 EntryBB->getTerminator()); 400 // The exception value comes back in context->data[0] 401 Idxs[1] = Zero; 402 Value *ExceptionAddr = GetElementPtrInst::Create(FCData, Idxs, Idxs+2, 403 "exception_gep", 404 EntryBB->getTerminator()); 405 406 // The result of the eh.selector call will be replaced with a 407 // a reference to the selector value returned in the function 408 // context. We leave the selector itself so the EH analysis later 409 // can use it. 410 for (int i = 0, e = EH_Selectors.size(); i < e; ++i) { 411 CallInst *I = EH_Selectors[i]; 412 Value *SelectorVal = new LoadInst(SelectorAddr, "select_val", true, I); 413 I->replaceAllUsesWith(SelectorVal); 414 } 415 // eh.exception calls are replaced with references to the proper 416 // location in the context. Unlike eh.selector, the eh.exception 417 // calls are removed entirely. 418 for (int i = 0, e = EH_Exceptions.size(); i < e; ++i) { 419 CallInst *I = EH_Exceptions[i]; 420 // Possible for there to be duplicates, so check to make sure 421 // the instruction hasn't already been removed. 422 if (!I->getParent()) continue; 423 Value *Val = new LoadInst(ExceptionAddr, "exception", true, I); 424 const Type *Ty = Type::getInt8PtrTy(F.getContext()); 425 Val = CastInst::Create(Instruction::IntToPtr, Val, Ty, "", I); 426 427 I->replaceAllUsesWith(Val); 428 I->eraseFromParent(); 429 } 430 431 // The entry block changes to have the eh.sjlj.setjmp, with a conditional 432 // branch to a dispatch block for non-zero returns. If we return normally, 433 // we're not handling an exception and just register the function context 434 // and continue. 435 436 // Create the dispatch block. The dispatch block is basically a big switch 437 // statement that goes to all of the invoke landing pads. 438 BasicBlock *DispatchBlock = 439 BasicBlock::Create(F.getContext(), "eh.sjlj.setjmp.catch", &F); 440 441 // Insert a load in the Catch block, and a switch on its value. By default, 442 // we go to a block that just does an unwind (which is the correct action 443 // for a standard call). 444 BasicBlock *UnwindBlock = 445 BasicBlock::Create(F.getContext(), "unwindbb", &F); 446 Unwinds.push_back(new UnwindInst(F.getContext(), UnwindBlock)); 447 448 Value *DispatchLoad = new LoadInst(CallSite, "invoke.num", true, 449 DispatchBlock); 450 SwitchInst *DispatchSwitch = 451 SwitchInst::Create(DispatchLoad, UnwindBlock, Invokes.size(), 452 DispatchBlock); 453 // Split the entry block to insert the conditional branch for the setjmp. 454 BasicBlock *ContBlock = EntryBB->splitBasicBlock(EntryBB->getTerminator(), 455 "eh.sjlj.setjmp.cont"); 456 457 // Populate the Function Context 458 // 1. LSDA address 459 // 2. Personality function address 460 // 3. jmpbuf (save SP, FP and call eh.sjlj.setjmp) 461 462 // LSDA address 463 Idxs[0] = Zero; 464 Idxs[1] = ConstantInt::get(Int32Ty, 4); 465 Value *LSDAFieldPtr = 466 GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, 467 "lsda_gep", 468 EntryBB->getTerminator()); 469 Value *LSDA = CallInst::Create(LSDAAddrFn, "lsda_addr", 470 EntryBB->getTerminator()); 471 new StoreInst(LSDA, LSDAFieldPtr, true, EntryBB->getTerminator()); 472 473 Idxs[1] = ConstantInt::get(Int32Ty, 3); 474 Value *PersonalityFieldPtr = 475 GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, 476 "lsda_gep", 477 EntryBB->getTerminator()); 478 new StoreInst(PersonalityFn, PersonalityFieldPtr, true, 479 EntryBB->getTerminator()); 480 481 // Save the frame pointer. 482 Idxs[1] = ConstantInt::get(Int32Ty, 5); 483 Value *JBufPtr 484 = GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, 485 "jbuf_gep", 486 EntryBB->getTerminator()); 487 Idxs[1] = ConstantInt::get(Int32Ty, 0); 488 Value *FramePtr = 489 GetElementPtrInst::Create(JBufPtr, Idxs, Idxs+2, "jbuf_fp_gep", 490 EntryBB->getTerminator()); 491 492 Value *Val = CallInst::Create(FrameAddrFn, 493 ConstantInt::get(Int32Ty, 0), 494 "fp", 495 EntryBB->getTerminator()); 496 new StoreInst(Val, FramePtr, true, EntryBB->getTerminator()); 497 498 // Save the stack pointer. 499 Idxs[1] = ConstantInt::get(Int32Ty, 2); 500 Value *StackPtr = 501 GetElementPtrInst::Create(JBufPtr, Idxs, Idxs+2, "jbuf_sp_gep", 502 EntryBB->getTerminator()); 503 504 Val = CallInst::Create(StackAddrFn, "sp", EntryBB->getTerminator()); 505 new StoreInst(Val, StackPtr, true, EntryBB->getTerminator()); 506 507 // Call the setjmp instrinsic. It fills in the rest of the jmpbuf. 508 Value *SetjmpArg = 509 CastInst::Create(Instruction::BitCast, JBufPtr, 510 Type::getInt8PtrTy(F.getContext()), "", 511 EntryBB->getTerminator()); 512 Value *DispatchVal = CallInst::Create(BuiltinSetjmpFn, SetjmpArg, 513 "dispatch", 514 EntryBB->getTerminator()); 515 // check the return value of the setjmp. non-zero goes to dispatcher. 516 Value *IsNormal = new ICmpInst(EntryBB->getTerminator(), 517 ICmpInst::ICMP_EQ, DispatchVal, Zero, 518 "notunwind"); 519 // Nuke the uncond branch. 520 EntryBB->getTerminator()->eraseFromParent(); 521 522 // Put in a new condbranch in its place. 523 BranchInst::Create(ContBlock, DispatchBlock, IsNormal, EntryBB); 524 525 // Register the function context and make sure it's known to not throw 526 CallInst *Register = 527 CallInst::Create(RegisterFn, FunctionContext, "", 528 ContBlock->getTerminator()); 529 Register->setDoesNotThrow(); 530 531 // At this point, we are all set up, update the invoke instructions 532 // to mark their call_site values, and fill in the dispatch switch 533 // accordingly. 534 for (unsigned i = 0, e = Invokes.size(); i != e; ++i) 535 markInvokeCallSite(Invokes[i], i+1, CallSite, DispatchSwitch); 536 537 // Mark call instructions that aren't nounwind as no-action 538 // (call_site == -1). Skip the entry block, as prior to then, no function 539 // context has been created for this function and any unexpected exceptions 540 // thrown will go directly to the caller's context, which is what we want 541 // anyway, so no need to do anything here. 542 for (Function::iterator BB = F.begin(), E = F.end(); ++BB != E;) { 543 for (BasicBlock::iterator I = BB->begin(), end = BB->end(); I != end; ++I) 544 if (CallInst *CI = dyn_cast<CallInst>(I)) { 545 // Ignore calls to the EH builtins (eh.selector, eh.exception) 546 Constant *Callee = CI->getCalledFunction(); 547 if (Callee != SelectorFn && Callee != ExceptionFn 548 && !CI->doesNotThrow()) 549 insertCallSiteStore(CI, -1, CallSite); 550 } 551 } 552 553 // Replace all unwinds with a branch to the unwind handler. 554 // ??? Should this ever happen with sjlj exceptions? 555 for (unsigned i = 0, e = Unwinds.size(); i != e; ++i) { 556 BranchInst::Create(UnwindBlock, Unwinds[i]); 557 Unwinds[i]->eraseFromParent(); 558 } 559 560 // Following any allocas not in the entry block, update the saved SP 561 // in the jmpbuf to the new value. 562 for (unsigned i = 0, e = JmpbufUpdatePoints.size(); i != e; ++i) { 563 Instruction *AI = JmpbufUpdatePoints[i]; 564 Instruction *StackAddr = CallInst::Create(StackAddrFn, "sp"); 565 StackAddr->insertAfter(AI); 566 Instruction *StoreStackAddr = new StoreInst(StackAddr, StackPtr, true); 567 StoreStackAddr->insertAfter(StackAddr); 568 } 569 570 // Finally, for any returns from this function, if this function contains an 571 // invoke, add a call to unregister the function context. 572 for (unsigned i = 0, e = Returns.size(); i != e; ++i) 573 CallInst::Create(UnregisterFn, FunctionContext, "", Returns[i]); 574 } 575 576 return true; 577} 578 579bool SjLjEHPass::runOnFunction(Function &F) { 580 bool Res = insertSjLjEHSupport(F); 581 return Res; 582} 583