X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FSjLjEHPrepare.cpp;h=2a16b649395c8a8d496a41b5e88d5f9c92098a83;hb=a3e49ea99afc3c9f43953bdc3b3bd77970ed510d;hp=2a7a7cdc3c996613563858fe00f932e138d811f1;hpb=3669915c6dc8d57a4525fb0c592e6c8c1df098f5;p=oota-llvm.git diff --git a/lib/CodeGen/SjLjEHPrepare.cpp b/lib/CodeGen/SjLjEHPrepare.cpp index 2a7a7cdc3c9..2a16b649395 100644 --- a/lib/CodeGen/SjLjEHPrepare.cpp +++ b/lib/CodeGen/SjLjEHPrepare.cpp @@ -1,4 +1,4 @@ -//===- SjLjEHPass.cpp - Eliminate Invoke & Unwind instructions -----------===// +//===- SjLjEHPrepare.cpp - Eliminate Invoke & Unwind instructions ---------===// // // The LLVM Compiler Infrastructure // @@ -12,307 +12,298 @@ // //===----------------------------------------------------------------------===// -#define DEBUG_TYPE "sjljehprepare" -#include "llvm/Transforms/Scalar.h" -#include "llvm/Constants.h" -#include "llvm/DerivedTypes.h" -#include "llvm/Instructions.h" -#include "llvm/Intrinsics.h" -#include "llvm/LLVMContext.h" -#include "llvm/Module.h" -#include "llvm/Pass.h" #include "llvm/CodeGen/Passes.h" -#include "llvm/Target/TargetLowering.h" -#include "llvm/Transforms/Utils/BasicBlockUtils.h" -#include "llvm/Transforms/Utils/Local.h" -#include "llvm/Support/Debug.h" #include "llvm/ADT/DenseMap.h" +#include "llvm/ADT/SetVector.h" +#include "llvm/ADT/SmallPtrSet.h" #include "llvm/ADT/SmallVector.h" #include "llvm/ADT/Statistic.h" +#include "llvm/IR/Constants.h" +#include "llvm/IR/DataLayout.h" +#include "llvm/IR/DerivedTypes.h" +#include "llvm/IR/IRBuilder.h" +#include "llvm/IR/Instructions.h" +#include "llvm/IR/Intrinsics.h" +#include "llvm/IR/LLVMContext.h" +#include "llvm/IR/Module.h" +#include "llvm/Pass.h" +#include "llvm/Support/CommandLine.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/raw_ostream.h" +#include "llvm/Target/TargetLowering.h" +#include "llvm/Target/TargetSubtargetInfo.h" +#include "llvm/Transforms/Scalar.h" +#include "llvm/Transforms/Utils/BasicBlockUtils.h" +#include "llvm/Transforms/Utils/Local.h" #include using namespace llvm; +#define DEBUG_TYPE "sjljehprepare" + STATISTIC(NumInvokes, "Number of invokes replaced"); -STATISTIC(NumUnwinds, "Number of unwinds replaced"); STATISTIC(NumSpilled, "Number of registers live across unwind edges"); namespace { - class SjLjEHPass : public FunctionPass { - const TargetLowering *TLI; - Type *FunctionContextTy; - Constant *RegisterFn; - Constant *UnregisterFn; - Constant *BuiltinSetjmpFn; - Constant *FrameAddrFn; - Constant *StackAddrFn; - Constant *StackRestoreFn; - Constant *LSDAAddrFn; - Value *PersonalityFn; - Constant *SelectorFn; - Constant *ExceptionFn; - Constant *CallSiteFn; - Constant *DispatchSetupFn; - Value *CallSite; - DenseMap LPadSuccMap; - public: - static char ID; // Pass identification, replacement for typeid - explicit SjLjEHPass(const TargetLowering *tli = NULL) - : FunctionPass(ID), TLI(tli) { } - bool doInitialization(Module &M); - bool runOnFunction(Function &F); - - virtual void getAnalysisUsage(AnalysisUsage &AU) const {} - const char *getPassName() const { - return "SJLJ Exception Handling preparation"; - } +class SjLjEHPrepare : public FunctionPass { + Type *doubleUnderDataTy; + Type *doubleUnderJBufTy; + Type *FunctionContextTy; + Constant *RegisterFn; + Constant *UnregisterFn; + Constant *BuiltinSetupDispatchFn; + Constant *FrameAddrFn; + Constant *StackAddrFn; + Constant *StackRestoreFn; + Constant *LSDAAddrFn; + Value *PersonalityFn; + Constant *CallSiteFn; + Constant *FuncCtxFn; + AllocaInst *FuncCtx; + +public: + static char ID; // Pass identification, replacement for typeid + explicit SjLjEHPrepare() : FunctionPass(ID) {} + bool doInitialization(Module &M) override; + bool runOnFunction(Function &F) override; + + void getAnalysisUsage(AnalysisUsage &AU) const override {} + const char *getPassName() const override { + return "SJLJ Exception Handling preparation"; + } - private: - void insertCallSiteStore(Instruction *I, int Number, Value *CallSite); - void markInvokeCallSite(InvokeInst *II, int InvokeNo, Value *CallSite, - SwitchInst *CatchSwitch); - void splitLiveRangesAcrossInvokes(SmallVector &Invokes); - void splitLandingPad(InvokeInst *II); - bool insertSjLjEHSupport(Function &F); - }; +private: + bool setupEntryBlockAndCallSites(Function &F); + void substituteLPadValues(LandingPadInst *LPI, Value *ExnVal, Value *SelVal); + Value *setupFunctionContext(Function &F, ArrayRef LPads); + void lowerIncomingArguments(Function &F); + void lowerAcrossUnwindEdges(Function &F, ArrayRef Invokes); + void insertCallSiteStore(Instruction *I, int Number); +}; } // end anonymous namespace -char SjLjEHPass::ID = 0; +char SjLjEHPrepare::ID = 0; +INITIALIZE_PASS(SjLjEHPrepare, "sjljehprepare", "Prepare SjLj exceptions", + false, false) -// Public Interface To the SjLjEHPass pass. -FunctionPass *llvm::createSjLjEHPass(const TargetLowering *TLI) { - return new SjLjEHPass(TLI); -} +// Public Interface To the SjLjEHPrepare pass. +FunctionPass *llvm::createSjLjEHPreparePass() { return new SjLjEHPrepare(); } // doInitialization - Set up decalarations and types needed to process // exceptions. -bool SjLjEHPass::doInitialization(Module &M) { +bool SjLjEHPrepare::doInitialization(Module &M) { // Build the function context structure. // builtin_setjmp uses a five word jbuf Type *VoidPtrTy = Type::getInt8PtrTy(M.getContext()); Type *Int32Ty = Type::getInt32Ty(M.getContext()); - FunctionContextTy = - StructType::get(VoidPtrTy, // __prev - Int32Ty, // call_site - ArrayType::get(Int32Ty, 4), // __data - VoidPtrTy, // __personality - VoidPtrTy, // __lsda - ArrayType::get(VoidPtrTy, 5), // __jbuf - NULL); - RegisterFn = M.getOrInsertFunction("_Unwind_SjLj_Register", - Type::getVoidTy(M.getContext()), - PointerType::getUnqual(FunctionContextTy), - (Type *)0); - UnregisterFn = - M.getOrInsertFunction("_Unwind_SjLj_Unregister", - Type::getVoidTy(M.getContext()), - PointerType::getUnqual(FunctionContextTy), - (Type *)0); + doubleUnderDataTy = ArrayType::get(Int32Ty, 4); + doubleUnderJBufTy = ArrayType::get(VoidPtrTy, 5); + FunctionContextTy = StructType::get(VoidPtrTy, // __prev + Int32Ty, // call_site + doubleUnderDataTy, // __data + VoidPtrTy, // __personality + VoidPtrTy, // __lsda + doubleUnderJBufTy, // __jbuf + nullptr); + RegisterFn = M.getOrInsertFunction( + "_Unwind_SjLj_Register", Type::getVoidTy(M.getContext()), + PointerType::getUnqual(FunctionContextTy), (Type *)nullptr); + UnregisterFn = M.getOrInsertFunction( + "_Unwind_SjLj_Unregister", Type::getVoidTy(M.getContext()), + PointerType::getUnqual(FunctionContextTy), (Type *)nullptr); FrameAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::frameaddress); StackAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::stacksave); StackRestoreFn = Intrinsic::getDeclaration(&M, Intrinsic::stackrestore); - BuiltinSetjmpFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_setjmp); + BuiltinSetupDispatchFn = + Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_setup_dispatch); LSDAAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_lsda); - SelectorFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_selector); - ExceptionFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_exception); CallSiteFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_callsite); - DispatchSetupFn - = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_dispatch_setup); - PersonalityFn = 0; + FuncCtxFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_functioncontext); + PersonalityFn = nullptr; return true; } /// insertCallSiteStore - Insert a store of the call-site value to the /// function context -void SjLjEHPass::insertCallSiteStore(Instruction *I, int Number, - Value *CallSite) { - ConstantInt *CallSiteNoC = ConstantInt::get(Type::getInt32Ty(I->getContext()), - Number); +void SjLjEHPrepare::insertCallSiteStore(Instruction *I, int Number) { + IRBuilder<> Builder(I); + + // Get a reference to the call_site field. + Type *Int32Ty = Type::getInt32Ty(I->getContext()); + Value *Zero = ConstantInt::get(Int32Ty, 0); + Value *One = ConstantInt::get(Int32Ty, 1); + Value *Idxs[2] = { Zero, One }; + Value *CallSite = + Builder.CreateGEP(FunctionContextTy, FuncCtx, Idxs, "call_site"); + // Insert a store of the call-site number - new StoreInst(CallSiteNoC, CallSite, true, I); // volatile + ConstantInt *CallSiteNoC = + ConstantInt::get(Type::getInt32Ty(I->getContext()), Number); + Builder.CreateStore(CallSiteNoC, CallSite, true /*volatile*/); } -/// splitLandingPad - Split a landing pad. This takes considerable care because -/// of PHIs and other nasties. The problem is that the jump table needs to jump -/// to the landing pad block. However, the landing pad block can be jumped to -/// only by an invoke instruction. So we clone the landingpad instruction into -/// its own basic block, have the invoke jump to there. The landingpad -/// instruction's basic block's successor is now the target for the jump table. -/// -/// But because of PHI nodes, we need to create another basic block for the jump -/// table to jump to. This is definitely a hack, because the values for the PHI -/// nodes may not be defined on the edge from the jump table. But that's okay, -/// because the jump table is simply a construct to mimic what is happening in -/// the CFG. So the values are mysteriously there, even though there is no value -/// for the PHI from the jump table's edge (hence calling this a hack). -void SjLjEHPass::splitLandingPad(InvokeInst *II) { - SmallVector NewBBs; - SplitLandingPadPredecessors(II->getUnwindDest(), II->getParent(), - ".1", ".2", this, NewBBs); - - // Create an empty block so that the jump table has something to jump to - // which doesn't have any PHI nodes. - BasicBlock *LPad = NewBBs[0]; - BasicBlock *Succ = *succ_begin(LPad); - BasicBlock *JumpTo = BasicBlock::Create(II->getContext(), "jt.land", - LPad->getParent(), Succ); - LPad->getTerminator()->eraseFromParent(); - BranchInst::Create(JumpTo, LPad); - BranchInst::Create(Succ, JumpTo); - LPadSuccMap[II] = JumpTo; - - for (BasicBlock::iterator I = Succ->begin(); isa(I); ++I) { - PHINode *PN = cast(I); - Value *Val = PN->removeIncomingValue(LPad, false); - PN->addIncoming(Val, JumpTo); - } +/// MarkBlocksLiveIn - Insert BB and all of its predescessors into LiveBBs until +/// we reach blocks we've already seen. +static void MarkBlocksLiveIn(BasicBlock *BB, + SmallPtrSetImpl &LiveBBs) { + if (!LiveBBs.insert(BB).second) + return; // already been here. + + for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) + MarkBlocksLiveIn(*PI, LiveBBs); } -/// markInvokeCallSite - Insert code to mark the call_site for this invoke -void SjLjEHPass::markInvokeCallSite(InvokeInst *II, int InvokeNo, - Value *CallSite, - SwitchInst *CatchSwitch) { - ConstantInt *CallSiteNoC= ConstantInt::get(Type::getInt32Ty(II->getContext()), - InvokeNo); - // The runtime comes back to the dispatcher with the call_site - 1 in - // the context. Odd, but there it is. - ConstantInt *SwitchValC = ConstantInt::get(Type::getInt32Ty(II->getContext()), - InvokeNo - 1); - - // If the unwind edge has phi nodes, split the edge. - if (isa(II->getUnwindDest()->begin())) { - // FIXME: New EH - This if-condition will be always true in the new scheme. - if (II->getUnwindDest()->isLandingPad()) - splitLandingPad(II); - else - SplitCriticalEdge(II, 1, this); - - // If there are any phi nodes left, they must have a single predecessor. - while (PHINode *PN = dyn_cast(II->getUnwindDest()->begin())) { - PN->replaceAllUsesWith(PN->getIncomingValue(0)); - PN->eraseFromParent(); - } +/// substituteLPadValues - Substitute the values returned by the landingpad +/// instruction with those returned by the personality function. +void SjLjEHPrepare::substituteLPadValues(LandingPadInst *LPI, Value *ExnVal, + Value *SelVal) { + SmallVector UseWorkList(LPI->user_begin(), LPI->user_end()); + while (!UseWorkList.empty()) { + Value *Val = UseWorkList.pop_back_val(); + ExtractValueInst *EVI = dyn_cast(Val); + if (!EVI) + continue; + if (EVI->getNumIndices() != 1) + continue; + if (*EVI->idx_begin() == 0) + EVI->replaceAllUsesWith(ExnVal); + else if (*EVI->idx_begin() == 1) + EVI->replaceAllUsesWith(SelVal); + if (EVI->getNumUses() == 0) + EVI->eraseFromParent(); } - // Insert the store of the call site value - insertCallSiteStore(II, InvokeNo, CallSite); + if (LPI->getNumUses() == 0) + return; + + // There are still some uses of LPI. Construct an aggregate with the exception + // values and replace the LPI with that aggregate. + Type *LPadType = LPI->getType(); + Value *LPadVal = UndefValue::get(LPadType); + IRBuilder<> Builder( + std::next(BasicBlock::iterator(cast(SelVal)))); + LPadVal = Builder.CreateInsertValue(LPadVal, ExnVal, 0, "lpad.val"); + LPadVal = Builder.CreateInsertValue(LPadVal, SelVal, 1, "lpad.val"); - // Record the call site value for the back end so it stays associated with - // the invoke. - CallInst::Create(CallSiteFn, CallSiteNoC, "", II); + LPI->replaceAllUsesWith(LPadVal); +} - // Add a switch case to our unwind block. - if (BasicBlock *SuccBB = LPadSuccMap[II]) { - CatchSwitch->addCase(SwitchValC, SuccBB); - } else { - CatchSwitch->addCase(SwitchValC, II->getUnwindDest()); +/// setupFunctionContext - Allocate the function context on the stack and fill +/// it with all of the data that we know at this point. +Value *SjLjEHPrepare::setupFunctionContext(Function &F, + ArrayRef LPads) { + BasicBlock *EntryBB = F.begin(); + + // Create an alloca for the incoming jump buffer ptr and the new jump buffer + // that needs to be restored on all exits from the function. This is an alloca + // because the value needs to be added to the global context list. + auto &DL = F.getParent()->getDataLayout(); + unsigned Align = DL.getPrefTypeAlignment(FunctionContextTy); + FuncCtx = new AllocaInst(FunctionContextTy, nullptr, Align, "fn_context", + EntryBB->begin()); + + // Fill in the function context structure. + for (unsigned I = 0, E = LPads.size(); I != E; ++I) { + LandingPadInst *LPI = LPads[I]; + IRBuilder<> Builder(LPI->getParent()->getFirstInsertionPt()); + + // Reference the __data field. + Value *FCData = + Builder.CreateConstGEP2_32(FunctionContextTy, FuncCtx, 0, 2, "__data"); + + // The exception values come back in context->__data[0]. + Value *ExceptionAddr = Builder.CreateConstGEP2_32(doubleUnderDataTy, FCData, + 0, 0, "exception_gep"); + Value *ExnVal = Builder.CreateLoad(ExceptionAddr, true, "exn_val"); + ExnVal = Builder.CreateIntToPtr(ExnVal, Builder.getInt8PtrTy()); + + Value *SelectorAddr = Builder.CreateConstGEP2_32(doubleUnderDataTy, FCData, + 0, 1, "exn_selector_gep"); + Value *SelVal = Builder.CreateLoad(SelectorAddr, true, "exn_selector_val"); + + substituteLPadValues(LPI, ExnVal, SelVal); } - // We still want this to look like an invoke so we emit the LSDA properly, - // so we don't transform the invoke into a call here. -} + // Personality function + IRBuilder<> Builder(EntryBB->getTerminator()); + if (!PersonalityFn) + PersonalityFn = F.getPersonalityFn(); + Value *PersonalityFieldPtr = Builder.CreateConstGEP2_32( + FunctionContextTy, FuncCtx, 0, 3, "pers_fn_gep"); + Builder.CreateStore( + Builder.CreateBitCast(PersonalityFn, Builder.getInt8PtrTy()), + PersonalityFieldPtr, /*isVolatile=*/true); -/// MarkBlocksLiveIn - Insert BB and all of its predescessors into LiveBBs until -/// we reach blocks we've already seen. -static void MarkBlocksLiveIn(BasicBlock *BB, std::set &LiveBBs) { - if (!LiveBBs.insert(BB).second) return; // already been here. + // LSDA address + Value *LSDA = Builder.CreateCall(LSDAAddrFn, {}, "lsda_addr"); + Value *LSDAFieldPtr = + Builder.CreateConstGEP2_32(FunctionContextTy, FuncCtx, 0, 4, "lsda_gep"); + Builder.CreateStore(LSDA, LSDAFieldPtr, /*isVolatile=*/true); - for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) - MarkBlocksLiveIn(*PI, LiveBBs); + return FuncCtx; } -/// splitLiveRangesAcrossInvokes - Each value that is live across an unwind edge -/// we spill into a stack location, guaranteeing that there is nothing live -/// across the unwind edge. This process also splits all critical edges -/// coming out of invoke's. -/// FIXME: Move this function to a common utility file (Local.cpp?) so -/// both SjLj and LowerInvoke can use it. -void SjLjEHPass:: -splitLiveRangesAcrossInvokes(SmallVector &Invokes) { - // First step, split all critical edges from invoke instructions. - for (unsigned i = 0, e = Invokes.size(); i != e; ++i) { - InvokeInst *II = Invokes[i]; - SplitCriticalEdge(II, 0, this); - - // FIXME: New EH - This if-condition will be always true in the new scheme. - if (II->getUnwindDest()->isLandingPad()) - splitLandingPad(II); - else - SplitCriticalEdge(II, 1, this); - - assert(!isa(II->getNormalDest()) && - !isa(II->getUnwindDest()) && - "Critical edge splitting left single entry phi nodes?"); - } - - Function *F = Invokes.back()->getParent()->getParent(); - - // To avoid having to handle incoming arguments specially, we lower each arg - // to a copy instruction in the entry block. This ensures that the argument - // value itself cannot be live across the entry block. - BasicBlock::iterator AfterAllocaInsertPt = F->begin()->begin(); - while (isa(AfterAllocaInsertPt) && - isa(cast(AfterAllocaInsertPt)->getArraySize())) - ++AfterAllocaInsertPt; - for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end(); - AI != E; ++AI) { +/// lowerIncomingArguments - To avoid having to handle incoming arguments +/// specially, we lower each arg to a copy instruction in the entry block. This +/// ensures that the argument value itself cannot be live out of the entry +/// block. +void SjLjEHPrepare::lowerIncomingArguments(Function &F) { + BasicBlock::iterator AfterAllocaInsPt = F.begin()->begin(); + while (isa(AfterAllocaInsPt) && + isa(cast(AfterAllocaInsPt)->getArraySize())) + ++AfterAllocaInsPt; + + for (Function::arg_iterator AI = F.arg_begin(), AE = F.arg_end(); AI != AE; + ++AI) { Type *Ty = AI->getType(); - // Aggregate types can't be cast, but are legal argument types, so we have - // to handle them differently. We use an extract/insert pair as a - // lightweight method to achieve the same goal. - if (isa(Ty) || isa(Ty) || isa(Ty)) { - Instruction *EI = ExtractValueInst::Create(AI, 0, "",AfterAllocaInsertPt); - Instruction *NI = InsertValueInst::Create(AI, EI, 0); - NI->insertAfter(EI); - AI->replaceAllUsesWith(NI); - // Set the operand of the instructions back to the AllocaInst. - EI->setOperand(0, AI); - NI->setOperand(0, AI); - } else { - // This is always a no-op cast because we're casting AI to AI->getType() - // so src and destination types are identical. BitCast is the only - // possibility. - CastInst *NC = new BitCastInst( - AI, AI->getType(), AI->getName()+".tmp", AfterAllocaInsertPt); - AI->replaceAllUsesWith(NC); - // Set the operand of the cast instruction back to the AllocaInst. - // Normally it's forbidden to replace a CastInst's operand because it - // could cause the opcode to reflect an illegal conversion. However, - // we're replacing it here with the same value it was constructed with. - // We do this because the above replaceAllUsesWith() clobbered the - // operand, but we want this one to remain. - NC->setOperand(0, AI); - } + + // Use 'select i8 true, %arg, undef' to simulate a 'no-op' instruction. + Value *TrueValue = ConstantInt::getTrue(F.getContext()); + Value *UndefValue = UndefValue::get(Ty); + Instruction *SI = SelectInst::Create(TrueValue, AI, UndefValue, + AI->getName() + ".tmp", + AfterAllocaInsPt); + AI->replaceAllUsesWith(SI); + + // Reset the operand, because it was clobbered by the RAUW above. + SI->setOperand(1, AI); } +} +/// lowerAcrossUnwindEdges - Find all variables which are alive across an unwind +/// edge and spill them. +void SjLjEHPrepare::lowerAcrossUnwindEdges(Function &F, + ArrayRef Invokes) { // Finally, scan the code looking for instructions with bad live ranges. - for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) - for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ++II) { - // Ignore obvious cases we don't have to handle. In particular, most + for (Function::iterator BB = F.begin(), BBE = F.end(); BB != BBE; ++BB) { + for (BasicBlock::iterator II = BB->begin(), IIE = BB->end(); II != IIE; + ++II) { + // Ignore obvious cases we don't have to handle. In particular, most // instructions either have no uses or only have a single use inside the - // current block. Ignore them quickly. + // current block. Ignore them quickly. Instruction *Inst = II; - if (Inst->use_empty()) continue; + if (Inst->use_empty()) + continue; if (Inst->hasOneUse() && - cast(Inst->use_back())->getParent() == BB && - !isa(Inst->use_back())) continue; + cast(Inst->user_back())->getParent() == BB && + !isa(Inst->user_back())) + continue; // If this is an alloca in the entry block, it's not a real register // value. if (AllocaInst *AI = dyn_cast(Inst)) - if (isa(AI->getArraySize()) && BB == F->begin()) + if (isa(AI->getArraySize()) && BB == F.begin()) continue; // Avoid iterator invalidation by copying users to a temporary vector. - SmallVector Users; - for (Value::use_iterator UI = Inst->use_begin(), E = Inst->use_end(); - UI != E; ++UI) { - Instruction *User = cast(*UI); - if (User->getParent() != BB || isa(User)) - Users.push_back(User); + SmallVector Users; + for (User *U : Inst->users()) { + Instruction *UI = cast(U); + if (UI->getParent() != BB || isa(UI)) + Users.push_back(UI); } // Find all of the blocks that this value is live in. - std::set LiveBBs; + SmallPtrSet LiveBBs; LiveBBs.insert(Inst->getParent()); while (!Users.empty()) { Instruction *U = Users.back(); @@ -335,7 +326,10 @@ splitLiveRangesAcrossInvokes(SmallVector &Invokes) { for (unsigned i = 0, e = Invokes.size(); i != e; ++i) { BasicBlock *UnwindBlock = Invokes[i]->getUnwindDest(); if (UnwindBlock != BB && LiveBBs.count(UnwindBlock)) { + DEBUG(dbgs() << "SJLJ Spill: " << *Inst << " around " + << UnwindBlock->getName() << "\n"); NeedsSpill = true; + break; } } @@ -344,361 +338,158 @@ splitLiveRangesAcrossInvokes(SmallVector &Invokes) { // the value to be reloaded from the stack slot, even those that aren't // in the unwind blocks. We should be more selective. if (NeedsSpill) { - ++NumSpilled; DemoteRegToStack(*Inst, true); + ++NumSpilled; } } -} - -/// CreateLandingPadLoad - Load the exception handling values and insert them -/// into a structure. -static Instruction *CreateLandingPadLoad(Function &F, Value *ExnAddr, - Value *SelAddr, - BasicBlock::iterator InsertPt) { - Value *Exn = new LoadInst(ExnAddr, "exn", false, - InsertPt); - Type *Ty = Type::getInt8PtrTy(F.getContext()); - Exn = CastInst::Create(Instruction::IntToPtr, Exn, Ty, "", InsertPt); - Value *Sel = new LoadInst(SelAddr, "sel", false, InsertPt); - - Ty = StructType::get(Exn->getType(), Sel->getType(), NULL); - InsertValueInst *LPadVal = InsertValueInst::Create(llvm::UndefValue::get(Ty), - Exn, 0, - "lpad.val", InsertPt); - return InsertValueInst::Create(LPadVal, Sel, 1, "lpad.val", InsertPt); -} - -/// ReplaceLandingPadVal - Replace the landingpad instruction's value with a -/// load from the stored values (via CreateLandingPadLoad). This looks through -/// PHI nodes, and removes them if they are dead. -static void ReplaceLandingPadVal(Function &F, Instruction *Inst, Value *ExnAddr, - Value *SelAddr) { - if (Inst->use_empty()) return; - - while (!Inst->use_empty()) { - Instruction *I = cast(Inst->use_back()); + } - if (PHINode *PN = dyn_cast(I)) { - ReplaceLandingPadVal(F, PN, ExnAddr, SelAddr); - if (PN->use_empty()) PN->eraseFromParent(); + // Go through the landing pads and remove any PHIs there. + for (unsigned i = 0, e = Invokes.size(); i != e; ++i) { + BasicBlock *UnwindBlock = Invokes[i]->getUnwindDest(); + LandingPadInst *LPI = UnwindBlock->getLandingPadInst(); + + // Place PHIs into a set to avoid invalidating the iterator. + SmallPtrSet PHIsToDemote; + for (BasicBlock::iterator PN = UnwindBlock->begin(); isa(PN); ++PN) + PHIsToDemote.insert(cast(PN)); + if (PHIsToDemote.empty()) continue; - } - I->replaceUsesOfWith(Inst, CreateLandingPadLoad(F, ExnAddr, SelAddr, I)); + // Demote the PHIs to the stack. + for (PHINode *PN : PHIsToDemote) + DemotePHIToStack(PN); + + // Move the landingpad instruction back to the top of the landing pad block. + LPI->moveBefore(UnwindBlock->begin()); } } -bool SjLjEHPass::insertSjLjEHSupport(Function &F) { - SmallVector Returns; - SmallVector Unwinds; - SmallVector Invokes; +/// setupEntryBlockAndCallSites - Setup the entry block by creating and filling +/// the function context and marking the call sites with the appropriate +/// values. These values are used by the DWARF EH emitter. +bool SjLjEHPrepare::setupEntryBlockAndCallSites(Function &F) { + SmallVector Returns; + SmallVector Invokes; + SmallSetVector LPads; + + // Look through the terminators of the basic blocks to find invokes. + for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) + if (InvokeInst *II = dyn_cast(BB->getTerminator())) { + if (Function *Callee = II->getCalledFunction()) + if (Callee->isIntrinsic() && + Callee->getIntrinsicID() == Intrinsic::donothing) { + // Remove the NOP invoke. + BranchInst::Create(II->getNormalDest(), II); + II->eraseFromParent(); + continue; + } - // Look through the terminators of the basic blocks to find invokes, returns - // and unwinds. - for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) { - if (ReturnInst *RI = dyn_cast(BB->getTerminator())) { - // Remember all return instructions in case we insert an invoke into this - // function. - Returns.push_back(RI); - } else if (InvokeInst *II = dyn_cast(BB->getTerminator())) { Invokes.push_back(II); - } else if (UnwindInst *UI = dyn_cast(BB->getTerminator())) { - Unwinds.push_back(UI); - } - } - - NumInvokes += Invokes.size(); - NumUnwinds += Unwinds.size(); - - // If we don't have any invokes, there's nothing to do. - if (Invokes.empty()) return false; - - // Find the eh.selector.*, eh.exception and alloca calls. - // - // Remember any allocas() that aren't in the entry block, as the - // jmpbuf saved SP will need to be updated for them. - // - // We'll use the first eh.selector to determine the right personality - // function to use. For SJLJ, we always use the same personality for the - // whole function, not on a per-selector basis. - // FIXME: That's a bit ugly. Better way? - SmallVector EH_Selectors; - SmallVector EH_Exceptions; - SmallVector JmpbufUpdatePoints; - - for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) { - // Note: Skip the entry block since there's nothing there that interests - // us. eh.selector and eh.exception shouldn't ever be there, and we - // want to disregard any allocas that are there. - // - // FIXME: This is awkward. The new EH scheme won't need to skip the entry - // block. - if (BB == F.begin()) { - if (InvokeInst *II = dyn_cast(F.begin()->getTerminator())) { - // FIXME: This will be always non-NULL in the new EH. - if (LandingPadInst *LPI = II->getUnwindDest()->getLandingPadInst()) - if (!PersonalityFn) PersonalityFn = LPI->getPersonalityFn(); - } - - continue; + LPads.insert(II->getUnwindDest()->getLandingPadInst()); + } else if (ReturnInst *RI = dyn_cast(BB->getTerminator())) { + Returns.push_back(RI); } - for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) { - if (CallInst *CI = dyn_cast(I)) { - if (CI->getCalledFunction() == SelectorFn) { - if (!PersonalityFn) PersonalityFn = CI->getArgOperand(1); - EH_Selectors.push_back(CI); - } else if (CI->getCalledFunction() == ExceptionFn) { - EH_Exceptions.push_back(CI); - } else if (CI->getCalledFunction() == StackRestoreFn) { - JmpbufUpdatePoints.push_back(CI); - } - } else if (AllocaInst *AI = dyn_cast(I)) { - JmpbufUpdatePoints.push_back(AI); - } else if (InvokeInst *II = dyn_cast(I)) { - // FIXME: This will be always non-NULL in the new EH. - if (LandingPadInst *LPI = II->getUnwindDest()->getLandingPadInst()) - if (!PersonalityFn) PersonalityFn = LPI->getPersonalityFn(); - } - } - } + if (Invokes.empty()) + return false; - // If we don't have any eh.selector calls, we can't determine the personality - // function. Without a personality function, we can't process exceptions. - if (!PersonalityFn) return false; + NumInvokes += Invokes.size(); - // We have invokes, so we need to add register/unregister calls to get this - // function onto the global unwind stack. - // - // First thing we need to do is scan the whole function for values that are - // live across unwind edges. Each value that is live across an unwind edge we - // spill into a stack location, guaranteeing that there is nothing live across - // the unwind edge. This process also splits all critical edges coming out of - // invoke's. - splitLiveRangesAcrossInvokes(Invokes); + lowerIncomingArguments(F); + lowerAcrossUnwindEdges(F, Invokes); + Value *FuncCtx = + setupFunctionContext(F, makeArrayRef(LPads.begin(), LPads.end())); + BasicBlock *EntryBB = F.begin(); + IRBuilder<> Builder(EntryBB->getTerminator()); - SmallVector LandingPads; - for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) { - if (InvokeInst *II = dyn_cast(BB->getTerminator())) - // FIXME: This will be always non-NULL in the new EH. - if (LandingPadInst *LPI = II->getUnwindDest()->getLandingPadInst()) - LandingPads.push_back(LPI); - } + // Get a reference to the jump buffer. + Value *JBufPtr = + Builder.CreateConstGEP2_32(FunctionContextTy, FuncCtx, 0, 5, "jbuf_gep"); + // Save the frame pointer. + Value *FramePtr = Builder.CreateConstGEP2_32(doubleUnderJBufTy, JBufPtr, 0, 0, + "jbuf_fp_gep"); - BasicBlock *EntryBB = F.begin(); - // Create an alloca for the incoming jump buffer ptr and the new jump buffer - // that needs to be restored on all exits from the function. This is an - // alloca because the value needs to be added to the global context list. - unsigned Align = 4; // FIXME: Should be a TLI check? - AllocaInst *FunctionContext = - new AllocaInst(FunctionContextTy, 0, Align, - "fcn_context", F.begin()->begin()); - - Value *Idxs[2]; - Type *Int32Ty = Type::getInt32Ty(F.getContext()); - Value *Zero = ConstantInt::get(Int32Ty, 0); - // We need to also keep around a reference to the call_site field - Idxs[0] = Zero; - Idxs[1] = ConstantInt::get(Int32Ty, 1); - CallSite = GetElementPtrInst::Create(FunctionContext, Idxs, "call_site", - EntryBB->getTerminator()); - - // The exception selector comes back in context->data[1] - Idxs[1] = ConstantInt::get(Int32Ty, 2); - Value *FCData = GetElementPtrInst::Create(FunctionContext, Idxs, "fc_data", - EntryBB->getTerminator()); - Idxs[1] = ConstantInt::get(Int32Ty, 1); - Value *SelectorAddr = GetElementPtrInst::Create(FCData, Idxs, - "exc_selector_gep", - EntryBB->getTerminator()); - // The exception value comes back in context->data[0] - Idxs[1] = Zero; - Value *ExceptionAddr = GetElementPtrInst::Create(FCData, Idxs, - "exception_gep", - EntryBB->getTerminator()); - - // The result of the eh.selector call will be replaced with a a reference to - // the selector value returned in the function context. We leave the selector - // itself so the EH analysis later can use it. - for (int i = 0, e = EH_Selectors.size(); i < e; ++i) { - CallInst *I = EH_Selectors[i]; - Value *SelectorVal = new LoadInst(SelectorAddr, "select_val", true, I); - I->replaceAllUsesWith(SelectorVal); - } + Value *Val = Builder.CreateCall(FrameAddrFn, Builder.getInt32(0), "fp"); + Builder.CreateStore(Val, FramePtr, /*isVolatile=*/true); - // eh.exception calls are replaced with references to the proper location in - // the context. Unlike eh.selector, the eh.exception calls are removed - // entirely. - for (int i = 0, e = EH_Exceptions.size(); i < e; ++i) { - CallInst *I = EH_Exceptions[i]; - // Possible for there to be duplicates, so check to make sure the - // instruction hasn't already been removed. - if (!I->getParent()) continue; - Value *Val = new LoadInst(ExceptionAddr, "exception", true, I); - Type *Ty = Type::getInt8PtrTy(F.getContext()); - Val = CastInst::Create(Instruction::IntToPtr, Val, Ty, "", I); - - I->replaceAllUsesWith(Val); - I->eraseFromParent(); - } + // Save the stack pointer. + Value *StackPtr = Builder.CreateConstGEP2_32(doubleUnderJBufTy, JBufPtr, 0, 2, + "jbuf_sp_gep"); - for (unsigned i = 0, e = LandingPads.size(); i != e; ++i) - ReplaceLandingPadVal(F, LandingPads[i], ExceptionAddr, SelectorAddr); - - // The entry block changes to have the eh.sjlj.setjmp, with a conditional - // branch to a dispatch block for non-zero returns. If we return normally, - // we're not handling an exception and just register the function context and - // continue. - - // Create the dispatch block. The dispatch block is basically a big switch - // statement that goes to all of the invoke landing pads. - BasicBlock *DispatchBlock = - BasicBlock::Create(F.getContext(), "eh.sjlj.setjmp.catch", &F); - - // Insert a load of the callsite in the dispatch block, and a switch on its - // value. By default, we issue a trap statement. - BasicBlock *TrapBlock = - BasicBlock::Create(F.getContext(), "trapbb", &F); - CallInst::Create(Intrinsic::getDeclaration(F.getParent(), Intrinsic::trap), - "", TrapBlock); - new UnreachableInst(F.getContext(), TrapBlock); - - Value *DispatchLoad = new LoadInst(CallSite, "invoke.num", true, - DispatchBlock); - SwitchInst *DispatchSwitch = - SwitchInst::Create(DispatchLoad, TrapBlock, Invokes.size(), - DispatchBlock); - // Split the entry block to insert the conditional branch for the setjmp. - BasicBlock *ContBlock = EntryBB->splitBasicBlock(EntryBB->getTerminator(), - "eh.sjlj.setjmp.cont"); - - // Populate the Function Context - // 1. LSDA address - // 2. Personality function address - // 3. jmpbuf (save SP, FP and call eh.sjlj.setjmp) + Val = Builder.CreateCall(StackAddrFn, {}, "sp"); + Builder.CreateStore(Val, StackPtr, /*isVolatile=*/true); - // LSDA address - Idxs[0] = Zero; - Idxs[1] = ConstantInt::get(Int32Ty, 4); - Value *LSDAFieldPtr = - GetElementPtrInst::Create(FunctionContext, Idxs, "lsda_gep", - EntryBB->getTerminator()); - Value *LSDA = CallInst::Create(LSDAAddrFn, "lsda_addr", - EntryBB->getTerminator()); - new StoreInst(LSDA, LSDAFieldPtr, true, EntryBB->getTerminator()); - - Idxs[1] = ConstantInt::get(Int32Ty, 3); - Value *PersonalityFieldPtr = - GetElementPtrInst::Create(FunctionContext, Idxs, "lsda_gep", - EntryBB->getTerminator()); - new StoreInst(PersonalityFn, PersonalityFieldPtr, true, - EntryBB->getTerminator()); + // Call the setup_dispatch instrinsic. It fills in the rest of the jmpbuf. + Builder.CreateCall(BuiltinSetupDispatchFn, {}); - // Save the frame pointer. - Idxs[1] = ConstantInt::get(Int32Ty, 5); - Value *JBufPtr - = GetElementPtrInst::Create(FunctionContext, Idxs, "jbuf_gep", - EntryBB->getTerminator()); - Idxs[1] = ConstantInt::get(Int32Ty, 0); - Value *FramePtr = - GetElementPtrInst::Create(JBufPtr, Idxs, "jbuf_fp_gep", - EntryBB->getTerminator()); - - Value *Val = CallInst::Create(FrameAddrFn, - ConstantInt::get(Int32Ty, 0), - "fp", - EntryBB->getTerminator()); - new StoreInst(Val, FramePtr, true, EntryBB->getTerminator()); + // Store a pointer to the function context so that the back-end will know + // where to look for it. + Value *FuncCtxArg = Builder.CreateBitCast(FuncCtx, Builder.getInt8PtrTy()); + Builder.CreateCall(FuncCtxFn, FuncCtxArg); - // Save the stack pointer. - Idxs[1] = ConstantInt::get(Int32Ty, 2); - Value *StackPtr = - GetElementPtrInst::Create(JBufPtr, Idxs, "jbuf_sp_gep", - EntryBB->getTerminator()); - - Val = CallInst::Create(StackAddrFn, "sp", EntryBB->getTerminator()); - new StoreInst(Val, StackPtr, true, EntryBB->getTerminator()); - - // Call the setjmp instrinsic. It fills in the rest of the jmpbuf. - Value *SetjmpArg = - CastInst::Create(Instruction::BitCast, JBufPtr, - Type::getInt8PtrTy(F.getContext()), "", - EntryBB->getTerminator()); - Value *DispatchVal = CallInst::Create(BuiltinSetjmpFn, SetjmpArg, - "dispatch", - EntryBB->getTerminator()); - - // Add a call to dispatch_setup after the setjmp call. This is expanded to any - // target-specific setup that needs to be done. - CallInst::Create(DispatchSetupFn, DispatchVal, "", EntryBB->getTerminator()); - - // check the return value of the setjmp. non-zero goes to dispatcher. - Value *IsNormal = new ICmpInst(EntryBB->getTerminator(), - ICmpInst::ICMP_EQ, DispatchVal, Zero, - "notunwind"); - // Nuke the uncond branch. - EntryBB->getTerminator()->eraseFromParent(); - - // Put in a new condbranch in its place. - BranchInst::Create(ContBlock, DispatchBlock, IsNormal, EntryBB); + // At this point, we are all set up, update the invoke instructions to mark + // their call_site values. + for (unsigned I = 0, E = Invokes.size(); I != E; ++I) { + insertCallSiteStore(Invokes[I], I + 1); - // Register the function context and make sure it's known to not throw - CallInst *Register = - CallInst::Create(RegisterFn, FunctionContext, "", - ContBlock->getTerminator()); - Register->setDoesNotThrow(); + ConstantInt *CallSiteNum = + ConstantInt::get(Type::getInt32Ty(F.getContext()), I + 1); - // At this point, we are all set up, update the invoke instructions to mark - // their call_site values, and fill in the dispatch switch accordingly. - for (unsigned i = 0, e = Invokes.size(); i != e; ++i) - markInvokeCallSite(Invokes[i], i+1, CallSite, DispatchSwitch); + // Record the call site value for the back end so it stays associated with + // the invoke. + CallInst::Create(CallSiteFn, CallSiteNum, "", Invokes[I]); + } // Mark call instructions that aren't nounwind as no-action (call_site == // -1). Skip the entry block, as prior to then, no function context has been // created for this function and any unexpected exceptions thrown will go // directly to the caller's context, which is what we want anyway, so no need // to do anything here. - for (Function::iterator BB = F.begin(), E = F.end(); ++BB != E;) { + for (Function::iterator BB = F.begin(), E = F.end(); ++BB != E;) for (BasicBlock::iterator I = BB->begin(), end = BB->end(); I != end; ++I) if (CallInst *CI = dyn_cast(I)) { - // Ignore calls to the EH builtins (eh.selector, eh.exception) - Constant *Callee = CI->getCalledFunction(); - if (Callee != SelectorFn && Callee != ExceptionFn - && !CI->doesNotThrow()) - insertCallSiteStore(CI, -1, CallSite); + if (!CI->doesNotThrow()) + insertCallSiteStore(CI, -1); } else if (ResumeInst *RI = dyn_cast(I)) { - insertCallSiteStore(RI, -1, CallSite); + insertCallSiteStore(RI, -1); } - } - // Replace all unwinds with a branch to the unwind handler. - // ??? Should this ever happen with sjlj exceptions? - for (unsigned i = 0, e = Unwinds.size(); i != e; ++i) { - BranchInst::Create(TrapBlock, Unwinds[i]); - Unwinds[i]->eraseFromParent(); - } + // Register the function context and make sure it's known to not throw + CallInst *Register = + CallInst::Create(RegisterFn, FuncCtx, "", EntryBB->getTerminator()); + Register->setDoesNotThrow(); // Following any allocas not in the entry block, update the saved SP in the // jmpbuf to the new value. - for (unsigned i = 0, e = JmpbufUpdatePoints.size(); i != e; ++i) { - Instruction *AI = JmpbufUpdatePoints[i]; - Instruction *StackAddr = CallInst::Create(StackAddrFn, "sp"); - StackAddr->insertAfter(AI); - Instruction *StoreStackAddr = new StoreInst(StackAddr, StackPtr, true); - StoreStackAddr->insertAfter(StackAddr); + for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) { + if (BB == F.begin()) + continue; + for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) { + if (CallInst *CI = dyn_cast(I)) { + if (CI->getCalledFunction() != StackRestoreFn) + continue; + } else if (!isa(I)) { + continue; + } + Instruction *StackAddr = CallInst::Create(StackAddrFn, "sp"); + StackAddr->insertAfter(I); + Instruction *StoreStackAddr = new StoreInst(StackAddr, StackPtr, true); + StoreStackAddr->insertAfter(StackAddr); + } } // Finally, for any returns from this function, if this function contains an // invoke, add a call to unregister the function context. - for (unsigned i = 0, e = Returns.size(); i != e; ++i) - CallInst::Create(UnregisterFn, FunctionContext, "", Returns[i]); + for (unsigned I = 0, E = Returns.size(); I != E; ++I) + CallInst::Create(UnregisterFn, FuncCtx, "", Returns[I]); return true; } -bool SjLjEHPass::runOnFunction(Function &F) { - bool Res = insertSjLjEHSupport(F); +bool SjLjEHPrepare::runOnFunction(Function &F) { + bool Res = setupEntryBlockAndCallSites(F); return Res; }