SjLjEHPrepare.cpp revision cfcccef926bd142c885dfa3f506bff933939350c
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/Target/TargetLowering.h" 26#include "llvm/Transforms/Utils/BasicBlockUtils.h" 27#include "llvm/Transforms/Utils/Local.h" 28#include "llvm/Support/Debug.h" 29#include "llvm/ADT/DenseMap.h" 30#include "llvm/ADT/SmallVector.h" 31#include "llvm/ADT/Statistic.h" 32#include <set> 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 const TargetLowering *TLI; 42 Type *FunctionContextTy; 43 Constant *RegisterFn; 44 Constant *UnregisterFn; 45 Constant *BuiltinSetjmpFn; 46 Constant *FrameAddrFn; 47 Constant *StackAddrFn; 48 Constant *StackRestoreFn; 49 Constant *LSDAAddrFn; 50 Value *PersonalityFn; 51 Constant *SelectorFn; 52 Constant *ExceptionFn; 53 Constant *CallSiteFn; 54 Constant *DispatchSetupFn; 55 Value *CallSite; 56 DenseMap<InvokeInst*, BasicBlock*> LPadSuccMap; 57 public: 58 static char ID; // Pass identification, replacement for typeid 59 explicit SjLjEHPass(const TargetLowering *tli = NULL) 60 : FunctionPass(ID), TLI(tli) { } 61 bool doInitialization(Module &M); 62 bool runOnFunction(Function &F); 63 64 virtual void getAnalysisUsage(AnalysisUsage &AU) const {} 65 const char *getPassName() const { 66 return "SJLJ Exception Handling preparation"; 67 } 68 69 private: 70 void insertCallSiteStore(Instruction *I, int Number, Value *CallSite); 71 void markInvokeCallSite(InvokeInst *II, int InvokeNo, Value *CallSite, 72 SwitchInst *CatchSwitch); 73 void splitLiveRangesAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes); 74 bool insertSjLjEHSupport(Function &F); 75 }; 76} // end anonymous namespace 77 78char SjLjEHPass::ID = 0; 79 80// Public Interface To the SjLjEHPass pass. 81FunctionPass *llvm::createSjLjEHPass(const TargetLowering *TLI) { 82 return new SjLjEHPass(TLI); 83} 84// doInitialization - Set up decalarations and types needed to process 85// exceptions. 86bool SjLjEHPass::doInitialization(Module &M) { 87 // Build the function context structure. 88 // builtin_setjmp uses a five word jbuf 89 Type *VoidPtrTy = Type::getInt8PtrTy(M.getContext()); 90 Type *Int32Ty = Type::getInt32Ty(M.getContext()); 91 FunctionContextTy = 92 StructType::get(VoidPtrTy, // __prev 93 Int32Ty, // call_site 94 ArrayType::get(Int32Ty, 4), // __data 95 VoidPtrTy, // __personality 96 VoidPtrTy, // __lsda 97 ArrayType::get(VoidPtrTy, 5), // __jbuf 98 NULL); 99 RegisterFn = M.getOrInsertFunction("_Unwind_SjLj_Register", 100 Type::getVoidTy(M.getContext()), 101 PointerType::getUnqual(FunctionContextTy), 102 (Type *)0); 103 UnregisterFn = 104 M.getOrInsertFunction("_Unwind_SjLj_Unregister", 105 Type::getVoidTy(M.getContext()), 106 PointerType::getUnqual(FunctionContextTy), 107 (Type *)0); 108 FrameAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::frameaddress); 109 StackAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::stacksave); 110 StackRestoreFn = Intrinsic::getDeclaration(&M, Intrinsic::stackrestore); 111 BuiltinSetjmpFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_setjmp); 112 LSDAAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_lsda); 113 SelectorFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_selector); 114 ExceptionFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_exception); 115 CallSiteFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_callsite); 116 DispatchSetupFn 117 = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_dispatch_setup); 118 PersonalityFn = 0; 119 120 return true; 121} 122 123/// insertCallSiteStore - Insert a store of the call-site value to the 124/// function context 125void SjLjEHPass::insertCallSiteStore(Instruction *I, int Number, 126 Value *CallSite) { 127 ConstantInt *CallSiteNoC = ConstantInt::get(Type::getInt32Ty(I->getContext()), 128 Number); 129 // Insert a store of the call-site number 130 new StoreInst(CallSiteNoC, CallSite, true, I); // volatile 131} 132 133/// markInvokeCallSite - Insert code to mark the call_site for this invoke 134void SjLjEHPass::markInvokeCallSite(InvokeInst *II, int InvokeNo, 135 Value *CallSite, 136 SwitchInst *CatchSwitch) { 137 ConstantInt *CallSiteNoC= ConstantInt::get(Type::getInt32Ty(II->getContext()), 138 InvokeNo); 139 // The runtime comes back to the dispatcher with the call_site - 1 in 140 // the context. Odd, but there it is. 141 ConstantInt *SwitchValC = ConstantInt::get(Type::getInt32Ty(II->getContext()), 142 InvokeNo - 1); 143 144 // If the unwind edge has phi nodes, split the edge. 145 if (isa<PHINode>(II->getUnwindDest()->begin())) { 146 SplitCriticalEdge(II, 1, this); 147 148 // If there are any phi nodes left, they must have a single predecessor. 149 while (PHINode *PN = dyn_cast<PHINode>(II->getUnwindDest()->begin())) { 150 PN->replaceAllUsesWith(PN->getIncomingValue(0)); 151 PN->eraseFromParent(); 152 } 153 } 154 155 // Insert the store of the call site value 156 insertCallSiteStore(II, InvokeNo, CallSite); 157 158 // Record the call site value for the back end so it stays associated with 159 // the invoke. 160 CallInst::Create(CallSiteFn, CallSiteNoC, "", II); 161 162 // Add a switch case to our unwind block. 163 if (BasicBlock *SuccBB = LPadSuccMap[II]) { 164 CatchSwitch->addCase(SwitchValC, SuccBB); 165 } else { 166 CatchSwitch->addCase(SwitchValC, II->getUnwindDest()); 167 } 168 169 // We still want this to look like an invoke so we emit the LSDA properly, 170 // so we don't transform the invoke into a call here. 171} 172 173/// MarkBlocksLiveIn - Insert BB and all of its predescessors into LiveBBs until 174/// we reach blocks we've already seen. 175static void MarkBlocksLiveIn(BasicBlock *BB, std::set<BasicBlock*> &LiveBBs) { 176 if (!LiveBBs.insert(BB).second) return; // already been here. 177 178 for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) 179 MarkBlocksLiveIn(*PI, LiveBBs); 180} 181 182/// splitLiveRangesAcrossInvokes - Each value that is live across an unwind edge 183/// we spill into a stack location, guaranteeing that there is nothing live 184/// across the unwind edge. This process also splits all critical edges 185/// coming out of invoke's. 186/// FIXME: Move this function to a common utility file (Local.cpp?) so 187/// both SjLj and LowerInvoke can use it. 188void SjLjEHPass:: 189splitLiveRangesAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes) { 190 // First step, split all critical edges from invoke instructions. 191 for (unsigned i = 0, e = Invokes.size(); i != e; ++i) { 192 InvokeInst *II = Invokes[i]; 193 SplitCriticalEdge(II, 0, this); 194 195 // FIXME: New EH - This if-condition will be always true in the new scheme. 196 if (II->getUnwindDest()->isLandingPad()) { 197 SmallVector<BasicBlock*, 2> NewBBs; 198 SplitLandingPadPredecessors(II->getUnwindDest(), II->getParent(), 199 ".1", ".2", this, NewBBs); 200 LPadSuccMap[II] = *succ_begin(NewBBs[0]); 201 } else { 202 SplitCriticalEdge(II, 1, this); 203 } 204 205 assert(!isa<PHINode>(II->getNormalDest()) && 206 !isa<PHINode>(II->getUnwindDest()) && 207 "Critical edge splitting left single entry phi nodes?"); 208 } 209 210 Function *F = Invokes.back()->getParent()->getParent(); 211 212 // To avoid having to handle incoming arguments specially, we lower each arg 213 // to a copy instruction in the entry block. This ensures that the argument 214 // value itself cannot be live across the entry block. 215 BasicBlock::iterator AfterAllocaInsertPt = F->begin()->begin(); 216 while (isa<AllocaInst>(AfterAllocaInsertPt) && 217 isa<ConstantInt>(cast<AllocaInst>(AfterAllocaInsertPt)->getArraySize())) 218 ++AfterAllocaInsertPt; 219 for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end(); 220 AI != E; ++AI) { 221 Type *Ty = AI->getType(); 222 // Aggregate types can't be cast, but are legal argument types, so we have 223 // to handle them differently. We use an extract/insert pair as a 224 // lightweight method to achieve the same goal. 225 if (isa<StructType>(Ty) || isa<ArrayType>(Ty) || isa<VectorType>(Ty)) { 226 Instruction *EI = ExtractValueInst::Create(AI, 0, "",AfterAllocaInsertPt); 227 Instruction *NI = InsertValueInst::Create(AI, EI, 0); 228 NI->insertAfter(EI); 229 AI->replaceAllUsesWith(NI); 230 // Set the operand of the instructions back to the AllocaInst. 231 EI->setOperand(0, AI); 232 NI->setOperand(0, AI); 233 } else { 234 // This is always a no-op cast because we're casting AI to AI->getType() 235 // so src and destination types are identical. BitCast is the only 236 // possibility. 237 CastInst *NC = new BitCastInst( 238 AI, AI->getType(), AI->getName()+".tmp", AfterAllocaInsertPt); 239 AI->replaceAllUsesWith(NC); 240 // Set the operand of the cast instruction back to the AllocaInst. 241 // Normally it's forbidden to replace a CastInst's operand because it 242 // could cause the opcode to reflect an illegal conversion. However, 243 // we're replacing it here with the same value it was constructed with. 244 // We do this because the above replaceAllUsesWith() clobbered the 245 // operand, but we want this one to remain. 246 NC->setOperand(0, AI); 247 } 248 } 249 250 // Finally, scan the code looking for instructions with bad live ranges. 251 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) 252 for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ++II) { 253 // Ignore obvious cases we don't have to handle. In particular, most 254 // instructions either have no uses or only have a single use inside the 255 // current block. Ignore them quickly. 256 Instruction *Inst = II; 257 if (Inst->use_empty()) continue; 258 if (Inst->hasOneUse() && 259 cast<Instruction>(Inst->use_back())->getParent() == BB && 260 !isa<PHINode>(Inst->use_back())) continue; 261 262 // If this is an alloca in the entry block, it's not a real register 263 // value. 264 if (AllocaInst *AI = dyn_cast<AllocaInst>(Inst)) 265 if (isa<ConstantInt>(AI->getArraySize()) && BB == F->begin()) 266 continue; 267 268 // Avoid iterator invalidation by copying users to a temporary vector. 269 SmallVector<Instruction*,16> Users; 270 for (Value::use_iterator UI = Inst->use_begin(), E = Inst->use_end(); 271 UI != E; ++UI) { 272 Instruction *User = cast<Instruction>(*UI); 273 if (User->getParent() != BB || isa<PHINode>(User)) 274 Users.push_back(User); 275 } 276 277 // Find all of the blocks that this value is live in. 278 std::set<BasicBlock*> LiveBBs; 279 LiveBBs.insert(Inst->getParent()); 280 while (!Users.empty()) { 281 Instruction *U = Users.back(); 282 Users.pop_back(); 283 284 if (!isa<PHINode>(U)) { 285 MarkBlocksLiveIn(U->getParent(), LiveBBs); 286 } else { 287 // Uses for a PHI node occur in their predecessor block. 288 PHINode *PN = cast<PHINode>(U); 289 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) 290 if (PN->getIncomingValue(i) == Inst) 291 MarkBlocksLiveIn(PN->getIncomingBlock(i), LiveBBs); 292 } 293 } 294 295 // Now that we know all of the blocks that this thing is live in, see if 296 // it includes any of the unwind locations. 297 bool NeedsSpill = false; 298 for (unsigned i = 0, e = Invokes.size(); i != e; ++i) { 299 BasicBlock *UnwindBlock = Invokes[i]->getUnwindDest(); 300 if (UnwindBlock != BB && LiveBBs.count(UnwindBlock)) { 301 NeedsSpill = true; 302 } 303 } 304 305 // If we decided we need a spill, do it. 306 // FIXME: Spilling this way is overkill, as it forces all uses of 307 // the value to be reloaded from the stack slot, even those that aren't 308 // in the unwind blocks. We should be more selective. 309 if (NeedsSpill) { 310 ++NumSpilled; 311 DemoteRegToStack(*Inst, true); 312 } 313 } 314} 315 316/// CreateLandingPadLoad - Load the exception handling values and insert them 317/// into a structure. 318static Instruction *CreateLandingPadLoad(Function &F, Value *ExnAddr, 319 Value *SelAddr, 320 BasicBlock::iterator InsertPt) { 321 Value *Exn = new LoadInst(ExnAddr, "exn", false, 322 InsertPt); 323 Type *Ty = Type::getInt8PtrTy(F.getContext()); 324 Exn = CastInst::Create(Instruction::IntToPtr, Exn, Ty, "", InsertPt); 325 Value *Sel = new LoadInst(SelAddr, "sel", false, InsertPt); 326 327 Ty = StructType::get(Exn->getType(), Sel->getType(), NULL); 328 InsertValueInst *LPadVal = InsertValueInst::Create(llvm::UndefValue::get(Ty), 329 Exn, 0, 330 "lpad.val", InsertPt); 331 return InsertValueInst::Create(LPadVal, Sel, 1, "lpad.val", InsertPt); 332} 333 334/// ReplaceLandingPadVal - Replace the landingpad instruction's value with a 335/// load from the stored values (via CreateLandingPadLoad). This looks through 336/// PHI nodes, and removes them if they are dead. 337static void ReplaceLandingPadVal(Function &F, Instruction *Inst, Value *ExnAddr, 338 Value *SelAddr) { 339 if (Inst->use_empty()) return; 340 341 while (!Inst->use_empty()) { 342 Instruction *I = cast<Instruction>(Inst->use_back()); 343 344 if (PHINode *PN = dyn_cast<PHINode>(I)) { 345 ReplaceLandingPadVal(F, PN, ExnAddr, SelAddr); 346 if (PN->use_empty()) PN->eraseFromParent(); 347 continue; 348 } 349 350 Inst->replaceAllUsesWith(CreateLandingPadLoad(F, ExnAddr, SelAddr, I)); 351 } 352} 353 354bool SjLjEHPass::insertSjLjEHSupport(Function &F) { 355 SmallVector<ReturnInst*,16> Returns; 356 SmallVector<UnwindInst*,16> Unwinds; 357 SmallVector<InvokeInst*,16> Invokes; 358 359 // Look through the terminators of the basic blocks to find invokes, returns 360 // and unwinds. 361 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) { 362 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) { 363 // Remember all return instructions in case we insert an invoke into this 364 // function. 365 Returns.push_back(RI); 366 } else if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) { 367 Invokes.push_back(II); 368 } else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) { 369 Unwinds.push_back(UI); 370 } 371 } 372 373 NumInvokes += Invokes.size(); 374 NumUnwinds += Unwinds.size(); 375 376 // If we don't have any invokes, there's nothing to do. 377 if (Invokes.empty()) return false; 378 379 // Find the eh.selector.*, eh.exception and alloca calls. 380 // 381 // Remember any allocas() that aren't in the entry block, as the 382 // jmpbuf saved SP will need to be updated for them. 383 // 384 // We'll use the first eh.selector to determine the right personality 385 // function to use. For SJLJ, we always use the same personality for the 386 // whole function, not on a per-selector basis. 387 // FIXME: That's a bit ugly. Better way? 388 SmallVector<CallInst*,16> EH_Selectors; 389 SmallVector<CallInst*,16> EH_Exceptions; 390 SmallVector<Instruction*,16> JmpbufUpdatePoints; 391 392 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) { 393 // Note: Skip the entry block since there's nothing there that interests 394 // us. eh.selector and eh.exception shouldn't ever be there, and we 395 // want to disregard any allocas that are there. 396 // 397 // FIXME: This is awkward. The new EH scheme won't need to skip the entry 398 // block. 399 if (BB == F.begin()) { 400 if (InvokeInst *II = dyn_cast<InvokeInst>(F.begin()->getTerminator())) { 401 // FIXME: This will be always non-NULL in the new EH. 402 if (LandingPadInst *LPI = II->getUnwindDest()->getLandingPadInst()) 403 if (!PersonalityFn) PersonalityFn = LPI->getPersonalityFn(); 404 } 405 406 continue; 407 } 408 409 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) { 410 if (CallInst *CI = dyn_cast<CallInst>(I)) { 411 if (CI->getCalledFunction() == SelectorFn) { 412 if (!PersonalityFn) PersonalityFn = CI->getArgOperand(1); 413 EH_Selectors.push_back(CI); 414 } else if (CI->getCalledFunction() == ExceptionFn) { 415 EH_Exceptions.push_back(CI); 416 } else if (CI->getCalledFunction() == StackRestoreFn) { 417 JmpbufUpdatePoints.push_back(CI); 418 } 419 } else if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) { 420 JmpbufUpdatePoints.push_back(AI); 421 } else if (InvokeInst *II = dyn_cast<InvokeInst>(I)) { 422 // FIXME: This will be always non-NULL in the new EH. 423 if (LandingPadInst *LPI = II->getUnwindDest()->getLandingPadInst()) 424 if (!PersonalityFn) PersonalityFn = LPI->getPersonalityFn(); 425 } 426 } 427 } 428 429 // If we don't have any eh.selector calls, we can't determine the personality 430 // function. Without a personality function, we can't process exceptions. 431 if (!PersonalityFn) return false; 432 433 // We have invokes, so we need to add register/unregister calls to get this 434 // function onto the global unwind stack. 435 // 436 // First thing we need to do is scan the whole function for values that are 437 // live across unwind edges. Each value that is live across an unwind edge we 438 // spill into a stack location, guaranteeing that there is nothing live across 439 // the unwind edge. This process also splits all critical edges coming out of 440 // invoke's. 441 splitLiveRangesAcrossInvokes(Invokes); 442 443 444 SmallVector<LandingPadInst*, 16> LandingPads; 445 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) { 446 if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) 447 // FIXME: This will be always non-NULL in the new EH. 448 if (LandingPadInst *LPI = II->getUnwindDest()->getLandingPadInst()) 449 LandingPads.push_back(LPI); 450 } 451 452 453 BasicBlock *EntryBB = F.begin(); 454 // Create an alloca for the incoming jump buffer ptr and the new jump buffer 455 // that needs to be restored on all exits from the function. This is an 456 // alloca because the value needs to be added to the global context list. 457 unsigned Align = 4; // FIXME: Should be a TLI check? 458 AllocaInst *FunctionContext = 459 new AllocaInst(FunctionContextTy, 0, Align, 460 "fcn_context", F.begin()->begin()); 461 462 Value *Idxs[2]; 463 Type *Int32Ty = Type::getInt32Ty(F.getContext()); 464 Value *Zero = ConstantInt::get(Int32Ty, 0); 465 // We need to also keep around a reference to the call_site field 466 Idxs[0] = Zero; 467 Idxs[1] = ConstantInt::get(Int32Ty, 1); 468 CallSite = GetElementPtrInst::Create(FunctionContext, Idxs, "call_site", 469 EntryBB->getTerminator()); 470 471 // The exception selector comes back in context->data[1] 472 Idxs[1] = ConstantInt::get(Int32Ty, 2); 473 Value *FCData = GetElementPtrInst::Create(FunctionContext, Idxs, "fc_data", 474 EntryBB->getTerminator()); 475 Idxs[1] = ConstantInt::get(Int32Ty, 1); 476 Value *SelectorAddr = GetElementPtrInst::Create(FCData, Idxs, 477 "exc_selector_gep", 478 EntryBB->getTerminator()); 479 // The exception value comes back in context->data[0] 480 Idxs[1] = Zero; 481 Value *ExceptionAddr = GetElementPtrInst::Create(FCData, Idxs, 482 "exception_gep", 483 EntryBB->getTerminator()); 484 485 // The result of the eh.selector call will be replaced with a a reference to 486 // the selector value returned in the function context. We leave the selector 487 // itself so the EH analysis later can use it. 488 for (int i = 0, e = EH_Selectors.size(); i < e; ++i) { 489 CallInst *I = EH_Selectors[i]; 490 Value *SelectorVal = new LoadInst(SelectorAddr, "select_val", true, I); 491 I->replaceAllUsesWith(SelectorVal); 492 } 493 494 // eh.exception calls are replaced with references to the proper location in 495 // the context. Unlike eh.selector, the eh.exception calls are removed 496 // entirely. 497 for (int i = 0, e = EH_Exceptions.size(); i < e; ++i) { 498 CallInst *I = EH_Exceptions[i]; 499 // Possible for there to be duplicates, so check to make sure the 500 // instruction hasn't already been removed. 501 if (!I->getParent()) continue; 502 Value *Val = new LoadInst(ExceptionAddr, "exception", true, I); 503 Type *Ty = Type::getInt8PtrTy(F.getContext()); 504 Val = CastInst::Create(Instruction::IntToPtr, Val, Ty, "", I); 505 506 I->replaceAllUsesWith(Val); 507 I->eraseFromParent(); 508 } 509 510 for (unsigned i = 0, e = LandingPads.size(); i != e; ++i) 511 ReplaceLandingPadVal(F, LandingPads[i], ExceptionAddr, SelectorAddr); 512 513 // The entry block changes to have the eh.sjlj.setjmp, with a conditional 514 // branch to a dispatch block for non-zero returns. If we return normally, 515 // we're not handling an exception and just register the function context and 516 // continue. 517 518 // Create the dispatch block. The dispatch block is basically a big switch 519 // statement that goes to all of the invoke landing pads. 520 BasicBlock *DispatchBlock = 521 BasicBlock::Create(F.getContext(), "eh.sjlj.setjmp.catch", &F); 522 523 // Insert a load of the callsite in the dispatch block, and a switch on its 524 // value. By default, we issue a trap statement. 525 BasicBlock *TrapBlock = 526 BasicBlock::Create(F.getContext(), "trapbb", &F); 527 CallInst::Create(Intrinsic::getDeclaration(F.getParent(), Intrinsic::trap), 528 "", TrapBlock); 529 new UnreachableInst(F.getContext(), TrapBlock); 530 531 Value *DispatchLoad = new LoadInst(CallSite, "invoke.num", true, 532 DispatchBlock); 533 SwitchInst *DispatchSwitch = 534 SwitchInst::Create(DispatchLoad, TrapBlock, Invokes.size(), 535 DispatchBlock); 536 // Split the entry block to insert the conditional branch for the setjmp. 537 BasicBlock *ContBlock = EntryBB->splitBasicBlock(EntryBB->getTerminator(), 538 "eh.sjlj.setjmp.cont"); 539 540 // Populate the Function Context 541 // 1. LSDA address 542 // 2. Personality function address 543 // 3. jmpbuf (save SP, FP and call eh.sjlj.setjmp) 544 545 // LSDA address 546 Idxs[0] = Zero; 547 Idxs[1] = ConstantInt::get(Int32Ty, 4); 548 Value *LSDAFieldPtr = 549 GetElementPtrInst::Create(FunctionContext, Idxs, "lsda_gep", 550 EntryBB->getTerminator()); 551 Value *LSDA = CallInst::Create(LSDAAddrFn, "lsda_addr", 552 EntryBB->getTerminator()); 553 new StoreInst(LSDA, LSDAFieldPtr, true, EntryBB->getTerminator()); 554 555 Idxs[1] = ConstantInt::get(Int32Ty, 3); 556 Value *PersonalityFieldPtr = 557 GetElementPtrInst::Create(FunctionContext, Idxs, "lsda_gep", 558 EntryBB->getTerminator()); 559 new StoreInst(PersonalityFn, PersonalityFieldPtr, true, 560 EntryBB->getTerminator()); 561 562 // Save the frame pointer. 563 Idxs[1] = ConstantInt::get(Int32Ty, 5); 564 Value *JBufPtr 565 = GetElementPtrInst::Create(FunctionContext, Idxs, "jbuf_gep", 566 EntryBB->getTerminator()); 567 Idxs[1] = ConstantInt::get(Int32Ty, 0); 568 Value *FramePtr = 569 GetElementPtrInst::Create(JBufPtr, Idxs, "jbuf_fp_gep", 570 EntryBB->getTerminator()); 571 572 Value *Val = CallInst::Create(FrameAddrFn, 573 ConstantInt::get(Int32Ty, 0), 574 "fp", 575 EntryBB->getTerminator()); 576 new StoreInst(Val, FramePtr, true, EntryBB->getTerminator()); 577 578 // Save the stack pointer. 579 Idxs[1] = ConstantInt::get(Int32Ty, 2); 580 Value *StackPtr = 581 GetElementPtrInst::Create(JBufPtr, Idxs, "jbuf_sp_gep", 582 EntryBB->getTerminator()); 583 584 Val = CallInst::Create(StackAddrFn, "sp", EntryBB->getTerminator()); 585 new StoreInst(Val, StackPtr, true, EntryBB->getTerminator()); 586 587 // Call the setjmp instrinsic. It fills in the rest of the jmpbuf. 588 Value *SetjmpArg = 589 CastInst::Create(Instruction::BitCast, JBufPtr, 590 Type::getInt8PtrTy(F.getContext()), "", 591 EntryBB->getTerminator()); 592 Value *DispatchVal = CallInst::Create(BuiltinSetjmpFn, SetjmpArg, 593 "dispatch", 594 EntryBB->getTerminator()); 595 596 // Add a call to dispatch_setup after the setjmp call. This is expanded to any 597 // target-specific setup that needs to be done. 598 CallInst::Create(DispatchSetupFn, DispatchVal, "", EntryBB->getTerminator()); 599 600 // check the return value of the setjmp. non-zero goes to dispatcher. 601 Value *IsNormal = new ICmpInst(EntryBB->getTerminator(), 602 ICmpInst::ICMP_EQ, DispatchVal, Zero, 603 "notunwind"); 604 // Nuke the uncond branch. 605 EntryBB->getTerminator()->eraseFromParent(); 606 607 // Put in a new condbranch in its place. 608 BranchInst::Create(ContBlock, DispatchBlock, IsNormal, EntryBB); 609 610 // Register the function context and make sure it's known to not throw 611 CallInst *Register = 612 CallInst::Create(RegisterFn, FunctionContext, "", 613 ContBlock->getTerminator()); 614 Register->setDoesNotThrow(); 615 616 // At this point, we are all set up, update the invoke instructions to mark 617 // their call_site values, and fill in the dispatch switch accordingly. 618 for (unsigned i = 0, e = Invokes.size(); i != e; ++i) 619 markInvokeCallSite(Invokes[i], i+1, CallSite, DispatchSwitch); 620 621 // Mark call instructions that aren't nounwind as no-action (call_site == 622 // -1). Skip the entry block, as prior to then, no function context has been 623 // created for this function and any unexpected exceptions thrown will go 624 // directly to the caller's context, which is what we want anyway, so no need 625 // to do anything here. 626 for (Function::iterator BB = F.begin(), E = F.end(); ++BB != E;) { 627 for (BasicBlock::iterator I = BB->begin(), end = BB->end(); I != end; ++I) 628 if (CallInst *CI = dyn_cast<CallInst>(I)) { 629 // Ignore calls to the EH builtins (eh.selector, eh.exception) 630 Constant *Callee = CI->getCalledFunction(); 631 if (Callee != SelectorFn && Callee != ExceptionFn 632 && !CI->doesNotThrow()) 633 insertCallSiteStore(CI, -1, CallSite); 634 } 635 } 636 637 // Replace all unwinds with a branch to the unwind handler. 638 // ??? Should this ever happen with sjlj exceptions? 639 for (unsigned i = 0, e = Unwinds.size(); i != e; ++i) { 640 BranchInst::Create(TrapBlock, Unwinds[i]); 641 Unwinds[i]->eraseFromParent(); 642 } 643 644 // Following any allocas not in the entry block, update the saved SP in the 645 // jmpbuf to the new value. 646 for (unsigned i = 0, e = JmpbufUpdatePoints.size(); i != e; ++i) { 647 Instruction *AI = JmpbufUpdatePoints[i]; 648 Instruction *StackAddr = CallInst::Create(StackAddrFn, "sp"); 649 StackAddr->insertAfter(AI); 650 Instruction *StoreStackAddr = new StoreInst(StackAddr, StackPtr, true); 651 StoreStackAddr->insertAfter(StackAddr); 652 } 653 654 // Finally, for any returns from this function, if this function contains an 655 // invoke, add a call to unregister the function context. 656 for (unsigned i = 0, e = Returns.size(); i != e; ++i) 657 CallInst::Create(UnregisterFn, FunctionContext, "", Returns[i]); 658 659 return true; 660} 661 662bool SjLjEHPass::runOnFunction(Function &F) { 663 bool Res = insertSjLjEHSupport(F); 664 return Res; 665} 666