SjLjEHPrepare.cpp revision f788854d20b12c60fd8b43c587adb3227b6b1bff
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/ADT/SmallVector.h" 25#include "llvm/ADT/Statistic.h" 26#include "llvm/CodeGen/Passes.h" 27#include "llvm/Support/Debug.h" 28#include "llvm/Target/TargetLowering.h" 29#include "llvm/Transforms/Utils/BasicBlockUtils.h" 30#include "llvm/Transforms/Utils/Local.h" 31#include <set> 32using namespace llvm; 33 34STATISTIC(NumInvokes, "Number of invokes replaced"); 35STATISTIC(NumUnwinds, "Number of unwinds replaced"); 36STATISTIC(NumSpilled, "Number of registers live across unwind edges"); 37 38namespace { 39 class SjLjEHPass : public FunctionPass { 40 41 const TargetLowering *TLI; 42 43 const Type *FunctionContextTy; 44 Constant *RegisterFn; 45 Constant *UnregisterFn; 46 Constant *BuiltinSetjmpFn; 47 Constant *FrameAddrFn; 48 Constant *StackAddrFn; 49 Constant *StackRestoreFn; 50 Constant *LSDAAddrFn; 51 Value *PersonalityFn; 52 Constant *SelectorFn; 53 Constant *ExceptionFn; 54 Constant *CallSiteFn; 55 Constant *DispatchSetupFn; 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 DispatchSetupFn 120 = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_dispatch_setup); 121 PersonalityFn = 0; 122 123 return true; 124} 125 126/// insertCallSiteStore - Insert a store of the call-site value to the 127/// function context 128void SjLjEHPass::insertCallSiteStore(Instruction *I, int Number, 129 Value *CallSite) { 130 ConstantInt *CallSiteNoC = ConstantInt::get(Type::getInt32Ty(I->getContext()), 131 Number); 132 // Insert a store of the call-site number 133 new StoreInst(CallSiteNoC, CallSite, true, I); // volatile 134} 135 136/// markInvokeCallSite - Insert code to mark the call_site for this invoke 137void SjLjEHPass::markInvokeCallSite(InvokeInst *II, int InvokeNo, 138 Value *CallSite, 139 SwitchInst *CatchSwitch) { 140 ConstantInt *CallSiteNoC= ConstantInt::get(Type::getInt32Ty(II->getContext()), 141 InvokeNo); 142 // The runtime comes back to the dispatcher with the call_site - 1 in 143 // the context. Odd, but there it is. 144 ConstantInt *SwitchValC = ConstantInt::get(Type::getInt32Ty(II->getContext()), 145 InvokeNo - 1); 146 147 // If the unwind edge has phi nodes, split the edge. 148 if (isa<PHINode>(II->getUnwindDest()->begin())) { 149 SplitCriticalEdge(II, 1, this); 150 151 // If there are any phi nodes left, they must have a single predecessor. 152 while (PHINode *PN = dyn_cast<PHINode>(II->getUnwindDest()->begin())) { 153 PN->replaceAllUsesWith(PN->getIncomingValue(0)); 154 PN->eraseFromParent(); 155 } 156 } 157 158 // Insert the store of the call site value 159 insertCallSiteStore(II, InvokeNo, CallSite); 160 161 // Record the call site value for the back end so it stays associated with 162 // the invoke. 163 CallInst::Create(CallSiteFn, CallSiteNoC, "", II); 164 165 // Add a switch case to our unwind block. 166 CatchSwitch->addCase(SwitchValC, II->getUnwindDest()); 167 // We still want this to look like an invoke so we emit the LSDA properly, 168 // so we don't transform the invoke into a call here. 169} 170 171/// MarkBlocksLiveIn - Insert BB and all of its predescessors into LiveBBs until 172/// we reach blocks we've already seen. 173static void MarkBlocksLiveIn(BasicBlock *BB, std::set<BasicBlock*> &LiveBBs) { 174 if (!LiveBBs.insert(BB).second) return; // already been here. 175 176 for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) 177 MarkBlocksLiveIn(*PI, LiveBBs); 178} 179 180/// splitLiveRangesAcrossInvokes - Each value that is live across an unwind edge 181/// we spill into a stack location, guaranteeing that there is nothing live 182/// across the unwind edge. This process also splits all critical edges 183/// coming out of invoke's. 184/// FIXME: Move this function to a common utility file (Local.cpp?) so 185/// both SjLj and LowerInvoke can use it. 186void SjLjEHPass:: 187splitLiveRangesAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes) { 188 // First step, split all critical edges from invoke instructions. 189 for (unsigned i = 0, e = Invokes.size(); i != e; ++i) { 190 InvokeInst *II = Invokes[i]; 191 SplitCriticalEdge(II, 0, this); 192 SplitCriticalEdge(II, 1, this); 193 assert(!isa<PHINode>(II->getNormalDest()) && 194 !isa<PHINode>(II->getUnwindDest()) && 195 "critical edge splitting left single entry phi nodes?"); 196 } 197 198 Function *F = Invokes.back()->getParent()->getParent(); 199 200 // To avoid having to handle incoming arguments specially, we lower each arg 201 // to a copy instruction in the entry block. This ensures that the argument 202 // value itself cannot be live across the entry block. 203 BasicBlock::iterator AfterAllocaInsertPt = F->begin()->begin(); 204 while (isa<AllocaInst>(AfterAllocaInsertPt) && 205 isa<ConstantInt>(cast<AllocaInst>(AfterAllocaInsertPt)->getArraySize())) 206 ++AfterAllocaInsertPt; 207 for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end(); 208 AI != E; ++AI) { 209 const Type *Ty = AI->getType(); 210 // Aggregate types can't be cast, but are legal argument types, so we have 211 // to handle them differently. We use an extract/insert pair as a 212 // lightweight method to achieve the same goal. 213 if (isa<StructType>(Ty) || isa<ArrayType>(Ty) || isa<VectorType>(Ty)) { 214 Instruction *EI = ExtractValueInst::Create(AI, 0, "",AfterAllocaInsertPt); 215 Instruction *NI = InsertValueInst::Create(AI, EI, 0); 216 NI->insertAfter(EI); 217 AI->replaceAllUsesWith(NI); 218 // Set the operand of the instructions back to the AllocaInst. 219 EI->setOperand(0, AI); 220 NI->setOperand(0, AI); 221 } else { 222 // This is always a no-op cast because we're casting AI to AI->getType() 223 // so src and destination types are identical. BitCast is the only 224 // possibility. 225 CastInst *NC = new BitCastInst( 226 AI, AI->getType(), AI->getName()+".tmp", AfterAllocaInsertPt); 227 AI->replaceAllUsesWith(NC); 228 // Set the operand of the cast instruction back to the AllocaInst. 229 // Normally it's forbidden to replace a CastInst's operand because it 230 // could cause the opcode to reflect an illegal conversion. However, 231 // we're replacing it here with the same value it was constructed with. 232 // We do this because the above replaceAllUsesWith() clobbered the 233 // operand, but we want this one to remain. 234 NC->setOperand(0, AI); 235 } 236 } 237 238 // Finally, scan the code looking for instructions with bad live ranges. 239 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) 240 for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ++II) { 241 // Ignore obvious cases we don't have to handle. In particular, most 242 // instructions either have no uses or only have a single use inside the 243 // current block. Ignore them quickly. 244 Instruction *Inst = II; 245 if (Inst->use_empty()) continue; 246 if (Inst->hasOneUse() && 247 cast<Instruction>(Inst->use_back())->getParent() == BB && 248 !isa<PHINode>(Inst->use_back())) continue; 249 250 // If this is an alloca in the entry block, it's not a real register 251 // value. 252 if (AllocaInst *AI = dyn_cast<AllocaInst>(Inst)) 253 if (isa<ConstantInt>(AI->getArraySize()) && BB == F->begin()) 254 continue; 255 256 // Avoid iterator invalidation by copying users to a temporary vector. 257 SmallVector<Instruction*,16> Users; 258 for (Value::use_iterator UI = Inst->use_begin(), E = Inst->use_end(); 259 UI != E; ++UI) { 260 Instruction *User = cast<Instruction>(*UI); 261 if (User->getParent() != BB || isa<PHINode>(User)) 262 Users.push_back(User); 263 } 264 265 // Find all of the blocks that this value is live in. 266 std::set<BasicBlock*> LiveBBs; 267 LiveBBs.insert(Inst->getParent()); 268 while (!Users.empty()) { 269 Instruction *U = Users.back(); 270 Users.pop_back(); 271 272 if (!isa<PHINode>(U)) { 273 MarkBlocksLiveIn(U->getParent(), LiveBBs); 274 } else { 275 // Uses for a PHI node occur in their predecessor block. 276 PHINode *PN = cast<PHINode>(U); 277 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) 278 if (PN->getIncomingValue(i) == Inst) 279 MarkBlocksLiveIn(PN->getIncomingBlock(i), LiveBBs); 280 } 281 } 282 283 // Now that we know all of the blocks that this thing is live in, see if 284 // it includes any of the unwind locations. 285 bool NeedsSpill = false; 286 for (unsigned i = 0, e = Invokes.size(); i != e; ++i) { 287 BasicBlock *UnwindBlock = Invokes[i]->getUnwindDest(); 288 if (UnwindBlock != BB && LiveBBs.count(UnwindBlock)) { 289 NeedsSpill = true; 290 } 291 } 292 293 // If we decided we need a spill, do it. 294 // FIXME: Spilling this way is overkill, as it forces all uses of 295 // the value to be reloaded from the stack slot, even those that aren't 296 // in the unwind blocks. We should be more selective. 297 if (NeedsSpill) { 298 ++NumSpilled; 299 DemoteRegToStack(*Inst, true); 300 } 301 } 302} 303 304bool SjLjEHPass::insertSjLjEHSupport(Function &F) { 305 SmallVector<ReturnInst*,16> Returns; 306 SmallVector<UnwindInst*,16> Unwinds; 307 SmallVector<InvokeInst*,16> Invokes; 308 309 // Look through the terminators of the basic blocks to find invokes, returns 310 // and unwinds. 311 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) { 312 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) { 313 // Remember all return instructions in case we insert an invoke into this 314 // function. 315 Returns.push_back(RI); 316 } else if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) { 317 Invokes.push_back(II); 318 } else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) { 319 Unwinds.push_back(UI); 320 } 321 } 322 // If we don't have any invokes or unwinds, there's nothing to do. 323 if (Unwinds.empty() && Invokes.empty()) return false; 324 325 // Find the eh.selector.*, eh.exception and alloca calls. 326 // 327 // Remember any allocas() that aren't in the entry block, as the 328 // jmpbuf saved SP will need to be updated for them. 329 // 330 // We'll use the first eh.selector to determine the right personality 331 // function to use. For SJLJ, we always use the same personality for the 332 // whole function, not on a per-selector basis. 333 // FIXME: That's a bit ugly. Better way? 334 SmallVector<CallInst*,16> EH_Selectors; 335 SmallVector<CallInst*,16> EH_Exceptions; 336 SmallVector<Instruction*,16> JmpbufUpdatePoints; 337 // Note: Skip the entry block since there's nothing there that interests 338 // us. eh.selector and eh.exception shouldn't ever be there, and we 339 // want to disregard any allocas that are there. 340 for (Function::iterator BB = F.begin(), E = F.end(); ++BB != E;) { 341 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) { 342 if (CallInst *CI = dyn_cast<CallInst>(I)) { 343 if (CI->getCalledFunction() == SelectorFn) { 344 if (!PersonalityFn) PersonalityFn = CI->getArgOperand(1); 345 EH_Selectors.push_back(CI); 346 } else if (CI->getCalledFunction() == ExceptionFn) { 347 EH_Exceptions.push_back(CI); 348 } else if (CI->getCalledFunction() == StackRestoreFn) { 349 JmpbufUpdatePoints.push_back(CI); 350 } 351 } else if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) { 352 JmpbufUpdatePoints.push_back(AI); 353 } 354 } 355 } 356 // If we don't have any eh.selector calls, we can't determine the personality 357 // function. Without a personality function, we can't process exceptions. 358 if (!PersonalityFn) return false; 359 360 NumInvokes += Invokes.size(); 361 NumUnwinds += Unwinds.size(); 362 363 if (!Invokes.empty()) { 364 // We have invokes, so we need to add register/unregister calls to get 365 // this function onto the global unwind stack. 366 // 367 // First thing we need to do is scan the whole function for values that are 368 // live across unwind edges. Each value that is live across an unwind edge 369 // we spill into a stack location, guaranteeing that there is nothing live 370 // across the unwind edge. This process also splits all critical edges 371 // coming out of invoke's. 372 splitLiveRangesAcrossInvokes(Invokes); 373 374 BasicBlock *EntryBB = F.begin(); 375 // Create an alloca for the incoming jump buffer ptr and the new jump buffer 376 // that needs to be restored on all exits from the function. This is an 377 // alloca because the value needs to be added to the global context list. 378 unsigned Align = 4; // FIXME: Should be a TLI check? 379 AllocaInst *FunctionContext = 380 new AllocaInst(FunctionContextTy, 0, Align, 381 "fcn_context", F.begin()->begin()); 382 383 Value *Idxs[2]; 384 const Type *Int32Ty = Type::getInt32Ty(F.getContext()); 385 Value *Zero = ConstantInt::get(Int32Ty, 0); 386 // We need to also keep around a reference to the call_site field 387 Idxs[0] = Zero; 388 Idxs[1] = ConstantInt::get(Int32Ty, 1); 389 CallSite = GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, 390 "call_site", 391 EntryBB->getTerminator()); 392 393 // The exception selector comes back in context->data[1] 394 Idxs[1] = ConstantInt::get(Int32Ty, 2); 395 Value *FCData = GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, 396 "fc_data", 397 EntryBB->getTerminator()); 398 Idxs[1] = ConstantInt::get(Int32Ty, 1); 399 Value *SelectorAddr = GetElementPtrInst::Create(FCData, Idxs, Idxs+2, 400 "exc_selector_gep", 401 EntryBB->getTerminator()); 402 // The exception value comes back in context->data[0] 403 Idxs[1] = Zero; 404 Value *ExceptionAddr = GetElementPtrInst::Create(FCData, Idxs, Idxs+2, 405 "exception_gep", 406 EntryBB->getTerminator()); 407 408 // The result of the eh.selector call will be replaced with a 409 // a reference to the selector value returned in the function 410 // context. We leave the selector itself so the EH analysis later 411 // can use it. 412 for (int i = 0, e = EH_Selectors.size(); i < e; ++i) { 413 CallInst *I = EH_Selectors[i]; 414 Value *SelectorVal = new LoadInst(SelectorAddr, "select_val", true, I); 415 I->replaceAllUsesWith(SelectorVal); 416 } 417 // eh.exception calls are replaced with references to the proper 418 // location in the context. Unlike eh.selector, the eh.exception 419 // calls are removed entirely. 420 for (int i = 0, e = EH_Exceptions.size(); i < e; ++i) { 421 CallInst *I = EH_Exceptions[i]; 422 // Possible for there to be duplicates, so check to make sure 423 // the instruction hasn't already been removed. 424 if (!I->getParent()) continue; 425 Value *Val = new LoadInst(ExceptionAddr, "exception", true, I); 426 const Type *Ty = Type::getInt8PtrTy(F.getContext()); 427 Val = CastInst::Create(Instruction::IntToPtr, Val, Ty, "", I); 428 429 I->replaceAllUsesWith(Val); 430 I->eraseFromParent(); 431 } 432 433 // The entry block changes to have the eh.sjlj.setjmp, with a conditional 434 // branch to a dispatch block for non-zero returns. If we return normally, 435 // we're not handling an exception and just register the function context 436 // and continue. 437 438 // Create the dispatch block. The dispatch block is basically a big switch 439 // statement that goes to all of the invoke landing pads. 440 BasicBlock *DispatchBlock = 441 BasicBlock::Create(F.getContext(), "eh.sjlj.setjmp.catch", &F); 442 443 // Add a call to dispatch_setup at the start of the dispatch block. This 444 // is expanded to any target-specific setup that needs to be done. 445 Value *SetupArg = 446 CastInst::Create(Instruction::BitCast, FunctionContext, 447 Type::getInt8PtrTy(F.getContext()), "", 448 DispatchBlock); 449 CallInst::Create(DispatchSetupFn, SetupArg, "", DispatchBlock); 450 451 // Insert a load of the callsite in the dispatch block, and a switch on 452 // its value. By default, we go to a block that just does an unwind 453 // (which is the correct action for a standard call). 454 BasicBlock *UnwindBlock = 455 BasicBlock::Create(F.getContext(), "unwindbb", &F); 456 Unwinds.push_back(new UnwindInst(F.getContext(), UnwindBlock)); 457 458 Value *DispatchLoad = new LoadInst(CallSite, "invoke.num", true, 459 DispatchBlock); 460 SwitchInst *DispatchSwitch = 461 SwitchInst::Create(DispatchLoad, UnwindBlock, Invokes.size(), 462 DispatchBlock); 463 // Split the entry block to insert the conditional branch for the setjmp. 464 BasicBlock *ContBlock = EntryBB->splitBasicBlock(EntryBB->getTerminator(), 465 "eh.sjlj.setjmp.cont"); 466 467 // Populate the Function Context 468 // 1. LSDA address 469 // 2. Personality function address 470 // 3. jmpbuf (save SP, FP and call eh.sjlj.setjmp) 471 472 // LSDA address 473 Idxs[0] = Zero; 474 Idxs[1] = ConstantInt::get(Int32Ty, 4); 475 Value *LSDAFieldPtr = 476 GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, 477 "lsda_gep", 478 EntryBB->getTerminator()); 479 Value *LSDA = CallInst::Create(LSDAAddrFn, "lsda_addr", 480 EntryBB->getTerminator()); 481 new StoreInst(LSDA, LSDAFieldPtr, true, EntryBB->getTerminator()); 482 483 Idxs[1] = ConstantInt::get(Int32Ty, 3); 484 Value *PersonalityFieldPtr = 485 GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, 486 "lsda_gep", 487 EntryBB->getTerminator()); 488 new StoreInst(PersonalityFn, PersonalityFieldPtr, true, 489 EntryBB->getTerminator()); 490 491 // Save the frame pointer. 492 Idxs[1] = ConstantInt::get(Int32Ty, 5); 493 Value *JBufPtr 494 = GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, 495 "jbuf_gep", 496 EntryBB->getTerminator()); 497 Idxs[1] = ConstantInt::get(Int32Ty, 0); 498 Value *FramePtr = 499 GetElementPtrInst::Create(JBufPtr, Idxs, Idxs+2, "jbuf_fp_gep", 500 EntryBB->getTerminator()); 501 502 Value *Val = CallInst::Create(FrameAddrFn, 503 ConstantInt::get(Int32Ty, 0), 504 "fp", 505 EntryBB->getTerminator()); 506 new StoreInst(Val, FramePtr, true, EntryBB->getTerminator()); 507 508 // Save the stack pointer. 509 Idxs[1] = ConstantInt::get(Int32Ty, 2); 510 Value *StackPtr = 511 GetElementPtrInst::Create(JBufPtr, Idxs, Idxs+2, "jbuf_sp_gep", 512 EntryBB->getTerminator()); 513 514 Val = CallInst::Create(StackAddrFn, "sp", EntryBB->getTerminator()); 515 new StoreInst(Val, StackPtr, true, EntryBB->getTerminator()); 516 517 // Call the setjmp instrinsic. It fills in the rest of the jmpbuf. 518 Value *SetjmpArg = 519 CastInst::Create(Instruction::BitCast, JBufPtr, 520 Type::getInt8PtrTy(F.getContext()), "", 521 EntryBB->getTerminator()); 522 Value *DispatchVal = CallInst::Create(BuiltinSetjmpFn, SetjmpArg, 523 "dispatch", 524 EntryBB->getTerminator()); 525 // check the return value of the setjmp. non-zero goes to dispatcher. 526 Value *IsNormal = new ICmpInst(EntryBB->getTerminator(), 527 ICmpInst::ICMP_EQ, DispatchVal, Zero, 528 "notunwind"); 529 // Nuke the uncond branch. 530 EntryBB->getTerminator()->eraseFromParent(); 531 532 // Put in a new condbranch in its place. 533 BranchInst::Create(ContBlock, DispatchBlock, IsNormal, EntryBB); 534 535 // Register the function context and make sure it's known to not throw 536 CallInst *Register = 537 CallInst::Create(RegisterFn, FunctionContext, "", 538 ContBlock->getTerminator()); 539 Register->setDoesNotThrow(); 540 541 // At this point, we are all set up, update the invoke instructions 542 // to mark their call_site values, and fill in the dispatch switch 543 // accordingly. 544 for (unsigned i = 0, e = Invokes.size(); i != e; ++i) 545 markInvokeCallSite(Invokes[i], i+1, CallSite, DispatchSwitch); 546 547 // Mark call instructions that aren't nounwind as no-action 548 // (call_site == -1). Skip the entry block, as prior to then, no function 549 // context has been created for this function and any unexpected exceptions 550 // thrown will go directly to the caller's context, which is what we want 551 // anyway, so no need to do anything here. 552 for (Function::iterator BB = F.begin(), E = F.end(); ++BB != E;) { 553 for (BasicBlock::iterator I = BB->begin(), end = BB->end(); I != end; ++I) 554 if (CallInst *CI = dyn_cast<CallInst>(I)) { 555 // Ignore calls to the EH builtins (eh.selector, eh.exception) 556 Constant *Callee = CI->getCalledFunction(); 557 if (Callee != SelectorFn && Callee != ExceptionFn 558 && !CI->doesNotThrow()) 559 insertCallSiteStore(CI, -1, CallSite); 560 } 561 } 562 563 // Replace all unwinds with a branch to the unwind handler. 564 // ??? Should this ever happen with sjlj exceptions? 565 for (unsigned i = 0, e = Unwinds.size(); i != e; ++i) { 566 BranchInst::Create(UnwindBlock, Unwinds[i]); 567 Unwinds[i]->eraseFromParent(); 568 } 569 570 // Following any allocas not in the entry block, update the saved SP 571 // in the jmpbuf to the new value. 572 for (unsigned i = 0, e = JmpbufUpdatePoints.size(); i != e; ++i) { 573 Instruction *AI = JmpbufUpdatePoints[i]; 574 Instruction *StackAddr = CallInst::Create(StackAddrFn, "sp"); 575 StackAddr->insertAfter(AI); 576 Instruction *StoreStackAddr = new StoreInst(StackAddr, StackPtr, true); 577 StoreStackAddr->insertAfter(StackAddr); 578 } 579 580 // Finally, for any returns from this function, if this function contains an 581 // invoke, add a call to unregister the function context. 582 for (unsigned i = 0, e = Returns.size(); i != e; ++i) 583 CallInst::Create(UnregisterFn, FunctionContext, "", Returns[i]); 584 } 585 586 return true; 587} 588 589bool SjLjEHPass::runOnFunction(Function &F) { 590 bool Res = insertSjLjEHSupport(F); 591 return Res; 592} 593