SjLjEHPrepare.cpp revision 198892
1198090Srdivacky//===- SjLjEHPass.cpp - Eliminate Invoke & Unwind instructions -----------===// 2198090Srdivacky// 3198090Srdivacky// The LLVM Compiler Infrastructure 4198090Srdivacky// 5198090Srdivacky// This file is distributed under the University of Illinois Open Source 6198090Srdivacky// License. See LICENSE.TXT for details. 7198090Srdivacky// 8198090Srdivacky//===----------------------------------------------------------------------===// 9198090Srdivacky// 10198090Srdivacky// This transformation is designed for use by code generators which use SjLj 11198090Srdivacky// based exception handling. 12198090Srdivacky// 13198090Srdivacky//===----------------------------------------------------------------------===// 14198090Srdivacky 15198090Srdivacky#define DEBUG_TYPE "sjljehprepare" 16198090Srdivacky#include "llvm/Transforms/Scalar.h" 17198090Srdivacky#include "llvm/Constants.h" 18198090Srdivacky#include "llvm/DerivedTypes.h" 19198090Srdivacky#include "llvm/Instructions.h" 20198090Srdivacky#include "llvm/Intrinsics.h" 21198090Srdivacky#include "llvm/LLVMContext.h" 22198090Srdivacky#include "llvm/Module.h" 23198090Srdivacky#include "llvm/Pass.h" 24198090Srdivacky#include "llvm/CodeGen/Passes.h" 25198090Srdivacky#include "llvm/Transforms/Utils/BasicBlockUtils.h" 26198090Srdivacky#include "llvm/Transforms/Utils/Local.h" 27198090Srdivacky#include "llvm/ADT/Statistic.h" 28198090Srdivacky#include "llvm/ADT/SmallVector.h" 29198090Srdivacky#include "llvm/Support/CommandLine.h" 30198090Srdivacky#include "llvm/Support/Debug.h" 31198090Srdivacky#include "llvm/Support/raw_ostream.h" 32198090Srdivacky#include "llvm/Target/TargetLowering.h" 33198090Srdivackyusing namespace llvm; 34198090Srdivacky 35198090SrdivackySTATISTIC(NumInvokes, "Number of invokes replaced"); 36198090SrdivackySTATISTIC(NumUnwinds, "Number of unwinds replaced"); 37198090SrdivackySTATISTIC(NumSpilled, "Number of registers live across unwind edges"); 38198090Srdivacky 39198090Srdivackynamespace { 40198892Srdivacky class SjLjEHPass : public FunctionPass { 41198090Srdivacky 42198090Srdivacky const TargetLowering *TLI; 43198090Srdivacky 44198090Srdivacky const Type *FunctionContextTy; 45198090Srdivacky Constant *RegisterFn; 46198090Srdivacky Constant *UnregisterFn; 47198090Srdivacky Constant *ResumeFn; 48198090Srdivacky Constant *BuiltinSetjmpFn; 49198090Srdivacky Constant *FrameAddrFn; 50198090Srdivacky Constant *LSDAAddrFn; 51198090Srdivacky Value *PersonalityFn; 52198090Srdivacky Constant *SelectorFn; 53198090Srdivacky Constant *ExceptionFn; 54198090Srdivacky 55198090Srdivacky Value *CallSite; 56198090Srdivacky public: 57198090Srdivacky static char ID; // Pass identification, replacement for typeid 58198090Srdivacky explicit SjLjEHPass(const TargetLowering *tli = NULL) 59198090Srdivacky : FunctionPass(&ID), TLI(tli) { } 60198090Srdivacky bool doInitialization(Module &M); 61198090Srdivacky bool runOnFunction(Function &F); 62198090Srdivacky 63198090Srdivacky virtual void getAnalysisUsage(AnalysisUsage &AU) const { } 64198090Srdivacky const char *getPassName() const { 65198090Srdivacky return "SJLJ Exception Handling preparation"; 66198090Srdivacky } 67198090Srdivacky 68198090Srdivacky private: 69198090Srdivacky void markInvokeCallSite(InvokeInst *II, unsigned InvokeNo, 70198090Srdivacky Value *CallSite, 71198090Srdivacky SwitchInst *CatchSwitch); 72198090Srdivacky void splitLiveRangesLiveAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes); 73198090Srdivacky bool insertSjLjEHSupport(Function &F); 74198090Srdivacky }; 75198090Srdivacky} // end anonymous namespace 76198090Srdivacky 77198090Srdivackychar SjLjEHPass::ID = 0; 78198090Srdivacky 79198090Srdivacky// Public Interface To the SjLjEHPass pass. 80198090SrdivackyFunctionPass *llvm::createSjLjEHPass(const TargetLowering *TLI) { 81198090Srdivacky return new SjLjEHPass(TLI); 82198090Srdivacky} 83198090Srdivacky// doInitialization - Set up decalarations and types needed to process 84198090Srdivacky// exceptions. 85198090Srdivackybool SjLjEHPass::doInitialization(Module &M) { 86198090Srdivacky // Build the function context structure. 87198090Srdivacky // builtin_setjmp uses a five word jbuf 88198090Srdivacky const Type *VoidPtrTy = 89198090Srdivacky Type::getInt8PtrTy(M.getContext()); 90198090Srdivacky const Type *Int32Ty = Type::getInt32Ty(M.getContext()); 91198090Srdivacky FunctionContextTy = 92198090Srdivacky StructType::get(M.getContext(), 93198090Srdivacky VoidPtrTy, // __prev 94198090Srdivacky Int32Ty, // call_site 95198090Srdivacky ArrayType::get(Int32Ty, 4), // __data 96198090Srdivacky VoidPtrTy, // __personality 97198090Srdivacky VoidPtrTy, // __lsda 98198090Srdivacky ArrayType::get(VoidPtrTy, 5), // __jbuf 99198090Srdivacky NULL); 100198090Srdivacky RegisterFn = M.getOrInsertFunction("_Unwind_SjLj_Register", 101198090Srdivacky Type::getVoidTy(M.getContext()), 102198090Srdivacky PointerType::getUnqual(FunctionContextTy), 103198090Srdivacky (Type *)0); 104198090Srdivacky UnregisterFn = 105198090Srdivacky M.getOrInsertFunction("_Unwind_SjLj_Unregister", 106198090Srdivacky Type::getVoidTy(M.getContext()), 107198090Srdivacky PointerType::getUnqual(FunctionContextTy), 108198090Srdivacky (Type *)0); 109198090Srdivacky ResumeFn = 110198090Srdivacky M.getOrInsertFunction("_Unwind_SjLj_Resume", 111198090Srdivacky Type::getVoidTy(M.getContext()), 112198090Srdivacky VoidPtrTy, 113198090Srdivacky (Type *)0); 114198090Srdivacky FrameAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::frameaddress); 115198090Srdivacky BuiltinSetjmpFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_setjmp); 116198090Srdivacky LSDAAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_lsda); 117198090Srdivacky SelectorFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_selector); 118198090Srdivacky ExceptionFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_exception); 119198090Srdivacky PersonalityFn = 0; 120198090Srdivacky 121198090Srdivacky return true; 122198090Srdivacky} 123198090Srdivacky 124198090Srdivacky/// markInvokeCallSite - Insert code to mark the call_site for this invoke 125198090Srdivackyvoid SjLjEHPass::markInvokeCallSite(InvokeInst *II, unsigned InvokeNo, 126198090Srdivacky Value *CallSite, 127198090Srdivacky SwitchInst *CatchSwitch) { 128198090Srdivacky ConstantInt *CallSiteNoC= ConstantInt::get(Type::getInt32Ty(II->getContext()), 129198090Srdivacky InvokeNo); 130198090Srdivacky // The runtime comes back to the dispatcher with the call_site - 1 in 131198090Srdivacky // the context. Odd, but there it is. 132198090Srdivacky ConstantInt *SwitchValC = ConstantInt::get(Type::getInt32Ty(II->getContext()), 133198090Srdivacky InvokeNo - 1); 134198090Srdivacky 135198090Srdivacky // If the unwind edge has phi nodes, split the edge. 136198090Srdivacky if (isa<PHINode>(II->getUnwindDest()->begin())) { 137198090Srdivacky SplitCriticalEdge(II, 1, this); 138198090Srdivacky 139198090Srdivacky // If there are any phi nodes left, they must have a single predecessor. 140198090Srdivacky while (PHINode *PN = dyn_cast<PHINode>(II->getUnwindDest()->begin())) { 141198090Srdivacky PN->replaceAllUsesWith(PN->getIncomingValue(0)); 142198090Srdivacky PN->eraseFromParent(); 143198090Srdivacky } 144198090Srdivacky } 145198090Srdivacky 146198090Srdivacky // Insert a store of the invoke num before the invoke and store zero into the 147198090Srdivacky // location afterward. 148198090Srdivacky new StoreInst(CallSiteNoC, CallSite, true, II); // volatile 149198090Srdivacky 150198090Srdivacky // Add a switch case to our unwind block. 151198090Srdivacky CatchSwitch->addCase(SwitchValC, II->getUnwindDest()); 152198090Srdivacky // We still want this to look like an invoke so we emit the LSDA properly 153198090Srdivacky // FIXME: ??? Or will this cause strangeness with mis-matched IDs like 154198090Srdivacky // when it was in the front end? 155198090Srdivacky} 156198090Srdivacky 157198090Srdivacky/// MarkBlocksLiveIn - Insert BB and all of its predescessors into LiveBBs until 158198090Srdivacky/// we reach blocks we've already seen. 159198090Srdivackystatic void MarkBlocksLiveIn(BasicBlock *BB, std::set<BasicBlock*> &LiveBBs) { 160198090Srdivacky if (!LiveBBs.insert(BB).second) return; // already been here. 161198090Srdivacky 162198090Srdivacky for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) 163198090Srdivacky MarkBlocksLiveIn(*PI, LiveBBs); 164198090Srdivacky} 165198090Srdivacky 166198090Srdivacky/// splitLiveRangesAcrossInvokes - Each value that is live across an unwind edge 167198090Srdivacky/// we spill into a stack location, guaranteeing that there is nothing live 168198090Srdivacky/// across the unwind edge. This process also splits all critical edges 169198090Srdivacky/// coming out of invoke's. 170198090Srdivackyvoid SjLjEHPass:: 171198090SrdivackysplitLiveRangesLiveAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes) { 172198090Srdivacky // First step, split all critical edges from invoke instructions. 173198090Srdivacky for (unsigned i = 0, e = Invokes.size(); i != e; ++i) { 174198090Srdivacky InvokeInst *II = Invokes[i]; 175198090Srdivacky SplitCriticalEdge(II, 0, this); 176198090Srdivacky SplitCriticalEdge(II, 1, this); 177198090Srdivacky assert(!isa<PHINode>(II->getNormalDest()) && 178198090Srdivacky !isa<PHINode>(II->getUnwindDest()) && 179198090Srdivacky "critical edge splitting left single entry phi nodes?"); 180198090Srdivacky } 181198090Srdivacky 182198090Srdivacky Function *F = Invokes.back()->getParent()->getParent(); 183198090Srdivacky 184198090Srdivacky // To avoid having to handle incoming arguments specially, we lower each arg 185198090Srdivacky // to a copy instruction in the entry block. This ensures that the argument 186198090Srdivacky // value itself cannot be live across the entry block. 187198090Srdivacky BasicBlock::iterator AfterAllocaInsertPt = F->begin()->begin(); 188198090Srdivacky while (isa<AllocaInst>(AfterAllocaInsertPt) && 189198090Srdivacky isa<ConstantInt>(cast<AllocaInst>(AfterAllocaInsertPt)->getArraySize())) 190198090Srdivacky ++AfterAllocaInsertPt; 191198090Srdivacky for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end(); 192198090Srdivacky AI != E; ++AI) { 193198090Srdivacky // This is always a no-op cast because we're casting AI to AI->getType() so 194198090Srdivacky // src and destination types are identical. BitCast is the only possibility. 195198090Srdivacky CastInst *NC = new BitCastInst( 196198090Srdivacky AI, AI->getType(), AI->getName()+".tmp", AfterAllocaInsertPt); 197198090Srdivacky AI->replaceAllUsesWith(NC); 198198090Srdivacky // Normally its is forbidden to replace a CastInst's operand because it 199198090Srdivacky // could cause the opcode to reflect an illegal conversion. However, we're 200198090Srdivacky // replacing it here with the same value it was constructed with to simply 201198090Srdivacky // make NC its user. 202198090Srdivacky NC->setOperand(0, AI); 203198090Srdivacky } 204198090Srdivacky 205198090Srdivacky // Finally, scan the code looking for instructions with bad live ranges. 206198090Srdivacky for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) 207198090Srdivacky for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ++II) { 208198090Srdivacky // Ignore obvious cases we don't have to handle. In particular, most 209198090Srdivacky // instructions either have no uses or only have a single use inside the 210198090Srdivacky // current block. Ignore them quickly. 211198090Srdivacky Instruction *Inst = II; 212198090Srdivacky if (Inst->use_empty()) continue; 213198090Srdivacky if (Inst->hasOneUse() && 214198090Srdivacky cast<Instruction>(Inst->use_back())->getParent() == BB && 215198090Srdivacky !isa<PHINode>(Inst->use_back())) continue; 216198090Srdivacky 217198090Srdivacky // If this is an alloca in the entry block, it's not a real register 218198090Srdivacky // value. 219198090Srdivacky if (AllocaInst *AI = dyn_cast<AllocaInst>(Inst)) 220198090Srdivacky if (isa<ConstantInt>(AI->getArraySize()) && BB == F->begin()) 221198090Srdivacky continue; 222198090Srdivacky 223198090Srdivacky // Avoid iterator invalidation by copying users to a temporary vector. 224198090Srdivacky SmallVector<Instruction*,16> Users; 225198090Srdivacky for (Value::use_iterator UI = Inst->use_begin(), E = Inst->use_end(); 226198090Srdivacky UI != E; ++UI) { 227198090Srdivacky Instruction *User = cast<Instruction>(*UI); 228198090Srdivacky if (User->getParent() != BB || isa<PHINode>(User)) 229198090Srdivacky Users.push_back(User); 230198090Srdivacky } 231198090Srdivacky 232198090Srdivacky // Find all of the blocks that this value is live in. 233198090Srdivacky std::set<BasicBlock*> LiveBBs; 234198090Srdivacky LiveBBs.insert(Inst->getParent()); 235198090Srdivacky while (!Users.empty()) { 236198090Srdivacky Instruction *U = Users.back(); 237198090Srdivacky Users.pop_back(); 238198090Srdivacky 239198090Srdivacky if (!isa<PHINode>(U)) { 240198090Srdivacky MarkBlocksLiveIn(U->getParent(), LiveBBs); 241198090Srdivacky } else { 242198090Srdivacky // Uses for a PHI node occur in their predecessor block. 243198090Srdivacky PHINode *PN = cast<PHINode>(U); 244198090Srdivacky for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) 245198090Srdivacky if (PN->getIncomingValue(i) == Inst) 246198090Srdivacky MarkBlocksLiveIn(PN->getIncomingBlock(i), LiveBBs); 247198090Srdivacky } 248198090Srdivacky } 249198090Srdivacky 250198090Srdivacky // Now that we know all of the blocks that this thing is live in, see if 251198090Srdivacky // it includes any of the unwind locations. 252198090Srdivacky bool NeedsSpill = false; 253198090Srdivacky for (unsigned i = 0, e = Invokes.size(); i != e; ++i) { 254198090Srdivacky BasicBlock *UnwindBlock = Invokes[i]->getUnwindDest(); 255198090Srdivacky if (UnwindBlock != BB && LiveBBs.count(UnwindBlock)) { 256198090Srdivacky NeedsSpill = true; 257198090Srdivacky } 258198090Srdivacky } 259198090Srdivacky 260198090Srdivacky // If we decided we need a spill, do it. 261198090Srdivacky if (NeedsSpill) { 262198090Srdivacky ++NumSpilled; 263198090Srdivacky DemoteRegToStack(*Inst, true); 264198090Srdivacky } 265198090Srdivacky } 266198090Srdivacky} 267198090Srdivacky 268198090Srdivackybool SjLjEHPass::insertSjLjEHSupport(Function &F) { 269198090Srdivacky SmallVector<ReturnInst*,16> Returns; 270198090Srdivacky SmallVector<UnwindInst*,16> Unwinds; 271198090Srdivacky SmallVector<InvokeInst*,16> Invokes; 272198090Srdivacky 273198090Srdivacky // Look through the terminators of the basic blocks to find invokes, returns 274198090Srdivacky // and unwinds 275198090Srdivacky for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) 276198090Srdivacky if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) { 277198090Srdivacky // Remember all return instructions in case we insert an invoke into this 278198090Srdivacky // function. 279198090Srdivacky Returns.push_back(RI); 280198090Srdivacky } else if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) { 281198090Srdivacky Invokes.push_back(II); 282198090Srdivacky } else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) { 283198090Srdivacky Unwinds.push_back(UI); 284198090Srdivacky } 285198090Srdivacky // If we don't have any invokes or unwinds, there's nothing to do. 286198090Srdivacky if (Unwinds.empty() && Invokes.empty()) return false; 287198090Srdivacky 288198090Srdivacky // Find the eh.selector.* and eh.exception calls. We'll use the first 289198090Srdivacky // eh.selector to determine the right personality function to use. For 290198090Srdivacky // SJLJ, we always use the same personality for the whole function, 291198090Srdivacky // not on a per-selector basis. 292198090Srdivacky // FIXME: That's a bit ugly. Better way? 293198090Srdivacky SmallVector<CallInst*,16> EH_Selectors; 294198090Srdivacky SmallVector<CallInst*,16> EH_Exceptions; 295198090Srdivacky for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) { 296198090Srdivacky for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) { 297198090Srdivacky if (CallInst *CI = dyn_cast<CallInst>(I)) { 298198090Srdivacky if (CI->getCalledFunction() == SelectorFn) { 299198090Srdivacky if (!PersonalityFn) PersonalityFn = CI->getOperand(2); 300198090Srdivacky EH_Selectors.push_back(CI); 301198090Srdivacky } else if (CI->getCalledFunction() == ExceptionFn) { 302198090Srdivacky EH_Exceptions.push_back(CI); 303198090Srdivacky } 304198090Srdivacky } 305198090Srdivacky } 306198090Srdivacky } 307198090Srdivacky // If we don't have any eh.selector calls, we can't determine the personality 308198090Srdivacky // function. Without a personality function, we can't process exceptions. 309198090Srdivacky if (!PersonalityFn) return false; 310198090Srdivacky 311198090Srdivacky NumInvokes += Invokes.size(); 312198090Srdivacky NumUnwinds += Unwinds.size(); 313198090Srdivacky 314198090Srdivacky if (!Invokes.empty()) { 315198090Srdivacky // We have invokes, so we need to add register/unregister calls to get 316198090Srdivacky // this function onto the global unwind stack. 317198090Srdivacky // 318198090Srdivacky // First thing we need to do is scan the whole function for values that are 319198090Srdivacky // live across unwind edges. Each value that is live across an unwind edge 320198090Srdivacky // we spill into a stack location, guaranteeing that there is nothing live 321198090Srdivacky // across the unwind edge. This process also splits all critical edges 322198090Srdivacky // coming out of invoke's. 323198090Srdivacky splitLiveRangesLiveAcrossInvokes(Invokes); 324198090Srdivacky 325198090Srdivacky BasicBlock *EntryBB = F.begin(); 326198090Srdivacky // Create an alloca for the incoming jump buffer ptr and the new jump buffer 327198090Srdivacky // that needs to be restored on all exits from the function. This is an 328198090Srdivacky // alloca because the value needs to be added to the global context list. 329198090Srdivacky unsigned Align = 4; // FIXME: Should be a TLI check? 330198090Srdivacky AllocaInst *FunctionContext = 331198090Srdivacky new AllocaInst(FunctionContextTy, 0, Align, 332198090Srdivacky "fcn_context", F.begin()->begin()); 333198090Srdivacky 334198090Srdivacky Value *Idxs[2]; 335198090Srdivacky const Type *Int32Ty = Type::getInt32Ty(F.getContext()); 336198090Srdivacky Value *Zero = ConstantInt::get(Int32Ty, 0); 337198090Srdivacky // We need to also keep around a reference to the call_site field 338198090Srdivacky Idxs[0] = Zero; 339198090Srdivacky Idxs[1] = ConstantInt::get(Int32Ty, 1); 340198090Srdivacky CallSite = GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, 341198090Srdivacky "call_site", 342198090Srdivacky EntryBB->getTerminator()); 343198090Srdivacky 344198090Srdivacky // The exception selector comes back in context->data[1] 345198090Srdivacky Idxs[1] = ConstantInt::get(Int32Ty, 2); 346198090Srdivacky Value *FCData = GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, 347198090Srdivacky "fc_data", 348198090Srdivacky EntryBB->getTerminator()); 349198090Srdivacky Idxs[1] = ConstantInt::get(Int32Ty, 1); 350198090Srdivacky Value *SelectorAddr = GetElementPtrInst::Create(FCData, Idxs, Idxs+2, 351198090Srdivacky "exc_selector_gep", 352198090Srdivacky EntryBB->getTerminator()); 353198090Srdivacky // The exception value comes back in context->data[0] 354198090Srdivacky Idxs[1] = Zero; 355198090Srdivacky Value *ExceptionAddr = GetElementPtrInst::Create(FCData, Idxs, Idxs+2, 356198090Srdivacky "exception_gep", 357198090Srdivacky EntryBB->getTerminator()); 358198090Srdivacky 359198090Srdivacky // The result of the eh.selector call will be replaced with a 360198090Srdivacky // a reference to the selector value returned in the function 361198090Srdivacky // context. We leave the selector itself so the EH analysis later 362198090Srdivacky // can use it. 363198090Srdivacky for (int i = 0, e = EH_Selectors.size(); i < e; ++i) { 364198090Srdivacky CallInst *I = EH_Selectors[i]; 365198090Srdivacky Value *SelectorVal = new LoadInst(SelectorAddr, "select_val", true, I); 366198090Srdivacky I->replaceAllUsesWith(SelectorVal); 367198090Srdivacky } 368198090Srdivacky // eh.exception calls are replaced with references to the proper 369198090Srdivacky // location in the context. Unlike eh.selector, the eh.exception 370198090Srdivacky // calls are removed entirely. 371198090Srdivacky for (int i = 0, e = EH_Exceptions.size(); i < e; ++i) { 372198090Srdivacky CallInst *I = EH_Exceptions[i]; 373198090Srdivacky // Possible for there to be duplicates, so check to make sure 374198090Srdivacky // the instruction hasn't already been removed. 375198090Srdivacky if (!I->getParent()) continue; 376198090Srdivacky Value *Val = new LoadInst(ExceptionAddr, "exception", true, I); 377198090Srdivacky const Type *Ty = Type::getInt8PtrTy(F.getContext()); 378198090Srdivacky Val = CastInst::Create(Instruction::IntToPtr, Val, Ty, "", I); 379198090Srdivacky 380198090Srdivacky I->replaceAllUsesWith(Val); 381198090Srdivacky I->eraseFromParent(); 382198090Srdivacky } 383198090Srdivacky 384198090Srdivacky 385198090Srdivacky 386198090Srdivacky 387198090Srdivacky // The entry block changes to have the eh.sjlj.setjmp, with a conditional 388198090Srdivacky // branch to a dispatch block for non-zero returns. If we return normally, 389198090Srdivacky // we're not handling an exception and just register the function context 390198090Srdivacky // and continue. 391198090Srdivacky 392198090Srdivacky // Create the dispatch block. The dispatch block is basically a big switch 393198090Srdivacky // statement that goes to all of the invoke landing pads. 394198090Srdivacky BasicBlock *DispatchBlock = 395198090Srdivacky BasicBlock::Create(F.getContext(), "eh.sjlj.setjmp.catch", &F); 396198090Srdivacky 397198090Srdivacky // Insert a load in the Catch block, and a switch on its value. By default, 398198090Srdivacky // we go to a block that just does an unwind (which is the correct action 399198090Srdivacky // for a standard call). 400198090Srdivacky BasicBlock *UnwindBlock = BasicBlock::Create(F.getContext(), "unwindbb", &F); 401198090Srdivacky Unwinds.push_back(new UnwindInst(F.getContext(), UnwindBlock)); 402198090Srdivacky 403198090Srdivacky Value *DispatchLoad = new LoadInst(CallSite, "invoke.num", true, 404198090Srdivacky DispatchBlock); 405198090Srdivacky SwitchInst *DispatchSwitch = 406198090Srdivacky SwitchInst::Create(DispatchLoad, UnwindBlock, Invokes.size(), DispatchBlock); 407198090Srdivacky // Split the entry block to insert the conditional branch for the setjmp. 408198090Srdivacky BasicBlock *ContBlock = EntryBB->splitBasicBlock(EntryBB->getTerminator(), 409198090Srdivacky "eh.sjlj.setjmp.cont"); 410198090Srdivacky 411198090Srdivacky // Populate the Function Context 412198090Srdivacky // 1. LSDA address 413198090Srdivacky // 2. Personality function address 414198090Srdivacky // 3. jmpbuf (save FP and call eh.sjlj.setjmp) 415198090Srdivacky 416198090Srdivacky // LSDA address 417198090Srdivacky Idxs[0] = Zero; 418198090Srdivacky Idxs[1] = ConstantInt::get(Int32Ty, 4); 419198090Srdivacky Value *LSDAFieldPtr = 420198090Srdivacky GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, 421198090Srdivacky "lsda_gep", 422198090Srdivacky EntryBB->getTerminator()); 423198090Srdivacky Value *LSDA = CallInst::Create(LSDAAddrFn, "lsda_addr", 424198090Srdivacky EntryBB->getTerminator()); 425198090Srdivacky new StoreInst(LSDA, LSDAFieldPtr, true, EntryBB->getTerminator()); 426198090Srdivacky 427198090Srdivacky Idxs[1] = ConstantInt::get(Int32Ty, 3); 428198090Srdivacky Value *PersonalityFieldPtr = 429198090Srdivacky GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, 430198090Srdivacky "lsda_gep", 431198090Srdivacky EntryBB->getTerminator()); 432198090Srdivacky new StoreInst(PersonalityFn, PersonalityFieldPtr, true, 433198090Srdivacky EntryBB->getTerminator()); 434198090Srdivacky 435198090Srdivacky // Save the frame pointer. 436198090Srdivacky Idxs[1] = ConstantInt::get(Int32Ty, 5); 437198090Srdivacky Value *FieldPtr 438198090Srdivacky = GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, 439198090Srdivacky "jbuf_gep", 440198090Srdivacky EntryBB->getTerminator()); 441198090Srdivacky Idxs[1] = ConstantInt::get(Int32Ty, 0); 442198090Srdivacky Value *ElemPtr = 443198090Srdivacky GetElementPtrInst::Create(FieldPtr, Idxs, Idxs+2, "jbuf_fp_gep", 444198090Srdivacky EntryBB->getTerminator()); 445198090Srdivacky 446198090Srdivacky Value *Val = CallInst::Create(FrameAddrFn, 447198090Srdivacky ConstantInt::get(Int32Ty, 0), 448198090Srdivacky "fp", 449198090Srdivacky EntryBB->getTerminator()); 450198090Srdivacky new StoreInst(Val, ElemPtr, true, EntryBB->getTerminator()); 451198090Srdivacky // Call the setjmp instrinsic. It fills in the rest of the jmpbuf 452198090Srdivacky Value *SetjmpArg = 453198090Srdivacky CastInst::Create(Instruction::BitCast, FieldPtr, 454198090Srdivacky Type::getInt8PtrTy(F.getContext()), "", 455198090Srdivacky EntryBB->getTerminator()); 456198090Srdivacky Value *DispatchVal = CallInst::Create(BuiltinSetjmpFn, SetjmpArg, 457198090Srdivacky "dispatch", 458198090Srdivacky EntryBB->getTerminator()); 459198090Srdivacky // check the return value of the setjmp. non-zero goes to dispatcher 460198090Srdivacky Value *IsNormal = new ICmpInst(EntryBB->getTerminator(), 461198090Srdivacky ICmpInst::ICMP_EQ, DispatchVal, Zero, 462198090Srdivacky "notunwind"); 463198090Srdivacky // Nuke the uncond branch. 464198090Srdivacky EntryBB->getTerminator()->eraseFromParent(); 465198090Srdivacky 466198090Srdivacky // Put in a new condbranch in its place. 467198090Srdivacky BranchInst::Create(ContBlock, DispatchBlock, IsNormal, EntryBB); 468198090Srdivacky 469198090Srdivacky // Register the function context and make sure it's known to not throw 470198090Srdivacky CallInst *Register = 471198090Srdivacky CallInst::Create(RegisterFn, FunctionContext, "", 472198090Srdivacky ContBlock->getTerminator()); 473198090Srdivacky Register->setDoesNotThrow(); 474198090Srdivacky 475198090Srdivacky // At this point, we are all set up, update the invoke instructions 476198090Srdivacky // to mark their call_site values, and fill in the dispatch switch 477198090Srdivacky // accordingly. 478198090Srdivacky for (unsigned i = 0, e = Invokes.size(); i != e; ++i) 479198090Srdivacky markInvokeCallSite(Invokes[i], i+1, CallSite, DispatchSwitch); 480198090Srdivacky 481198090Srdivacky // The front end has likely added calls to _Unwind_Resume. We need 482198090Srdivacky // to find those calls and mark the call_site as -1 immediately prior. 483198090Srdivacky // resume is a noreturn function, so any block that has a call to it 484198090Srdivacky // should end in an 'unreachable' instruction with the call immediately 485198090Srdivacky // prior. That's how we'll search. 486198090Srdivacky // ??? There's got to be a better way. this is fugly. 487198090Srdivacky for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) 488198090Srdivacky if ((dyn_cast<UnreachableInst>(BB->getTerminator()))) { 489198090Srdivacky BasicBlock::iterator I = BB->getTerminator(); 490198090Srdivacky // Check the previous instruction and see if it's a resume call 491198090Srdivacky if (I == BB->begin()) continue; 492198090Srdivacky if (CallInst *CI = dyn_cast<CallInst>(--I)) { 493198090Srdivacky if (CI->getCalledFunction() == ResumeFn) { 494198090Srdivacky Value *NegativeOne = Constant::getAllOnesValue(Int32Ty); 495198090Srdivacky new StoreInst(NegativeOne, CallSite, true, I); // volatile 496198090Srdivacky } 497198090Srdivacky } 498198090Srdivacky } 499198090Srdivacky 500198090Srdivacky // Replace all unwinds with a branch to the unwind handler. 501198090Srdivacky // ??? Should this ever happen with sjlj exceptions? 502198090Srdivacky for (unsigned i = 0, e = Unwinds.size(); i != e; ++i) { 503198090Srdivacky BranchInst::Create(UnwindBlock, Unwinds[i]); 504198090Srdivacky Unwinds[i]->eraseFromParent(); 505198090Srdivacky } 506198090Srdivacky 507198090Srdivacky // Finally, for any returns from this function, if this function contains an 508198090Srdivacky // invoke, add a call to unregister the function context. 509198090Srdivacky for (unsigned i = 0, e = Returns.size(); i != e; ++i) 510198090Srdivacky CallInst::Create(UnregisterFn, FunctionContext, "", Returns[i]); 511198090Srdivacky } 512198090Srdivacky 513198090Srdivacky return true; 514198090Srdivacky} 515198090Srdivacky 516198090Srdivackybool SjLjEHPass::runOnFunction(Function &F) { 517198090Srdivacky bool Res = insertSjLjEHSupport(F); 518198090Srdivacky return Res; 519198090Srdivacky} 520