diff options
Diffstat (limited to 'lib/CodeGen/SjLjEHPrepare.cpp')
| -rw-r--r-- | lib/CodeGen/SjLjEHPrepare.cpp | 514 |
1 files changed, 476 insertions, 38 deletions
diff --git a/lib/CodeGen/SjLjEHPrepare.cpp b/lib/CodeGen/SjLjEHPrepare.cpp index 65a33da..ded2459d 100644 --- a/lib/CodeGen/SjLjEHPrepare.cpp +++ b/lib/CodeGen/SjLjEHPrepare.cpp @@ -21,26 +21,31 @@ #include "llvm/LLVMContext.h" #include "llvm/Module.h" #include "llvm/Pass.h" -#include "llvm/ADT/SmallVector.h" -#include "llvm/ADT/Statistic.h" #include "llvm/CodeGen/Passes.h" -#include "llvm/Support/Debug.h" +#include "llvm/Target/TargetData.h" #include "llvm/Target/TargetLowering.h" #include "llvm/Transforms/Utils/BasicBlockUtils.h" #include "llvm/Transforms/Utils/Local.h" +#include "llvm/Support/CommandLine.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/IRBuilder.h" +#include "llvm/ADT/DenseMap.h" +#include "llvm/ADT/SmallVector.h" +#include "llvm/ADT/Statistic.h" #include <set> using namespace llvm; +static cl::opt<bool> DisableOldSjLjEH("disable-old-sjlj-eh", cl::Hidden, + cl::desc("Disable the old SjLj EH preparation pass")); + 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; - - const Type *FunctionContextTy; + Type *FunctionContextTy; Constant *RegisterFn; Constant *UnregisterFn; Constant *BuiltinSetjmpFn; @@ -53,8 +58,9 @@ namespace { Constant *ExceptionFn; Constant *CallSiteFn; Constant *DispatchSetupFn; - + Constant *FuncCtxFn; Value *CallSite; + DenseMap<InvokeInst*, BasicBlock*> LPadSuccMap; public: static char ID; // Pass identification, replacement for typeid explicit SjLjEHPass(const TargetLowering *tli = NULL) @@ -62,16 +68,22 @@ namespace { bool doInitialization(Module &M); bool runOnFunction(Function &F); - virtual void getAnalysisUsage(AnalysisUsage &AU) const { } + virtual void getAnalysisUsage(AnalysisUsage &AU) const {} const char *getPassName() const { return "SJLJ Exception Handling preparation"; } private: + bool setupEntryBlockAndCallSites(Function &F); + Value *setupFunctionContext(Function &F, ArrayRef<LandingPadInst*> LPads); + void lowerIncomingArguments(Function &F); + void lowerAcrossUnwindEdges(Function &F, ArrayRef<InvokeInst*> Invokes); + void insertCallSiteStore(Instruction *I, int Number, Value *CallSite); void markInvokeCallSite(InvokeInst *II, int InvokeNo, Value *CallSite, SwitchInst *CatchSwitch); void splitLiveRangesAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes); + void splitLandingPad(InvokeInst *II); bool insertSjLjEHSupport(Function &F); }; } // end anonymous namespace @@ -116,6 +128,7 @@ bool SjLjEHPass::doInitialization(Module &M) { CallSiteFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_callsite); DispatchSetupFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_dispatch_setup); + FuncCtxFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_functioncontext); PersonalityFn = 0; return true; @@ -131,6 +144,42 @@ void SjLjEHPass::insertCallSiteStore(Instruction *I, int Number, new StoreInst(CallSiteNoC, CallSite, true, I); // 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<BasicBlock*, 2> 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<PHINode>(I); ++I) { + PHINode *PN = cast<PHINode>(I); + Value *Val = PN->removeIncomingValue(LPad, false); + PN->addIncoming(Val, JumpTo); + } +} + /// markInvokeCallSite - Insert code to mark the call_site for this invoke void SjLjEHPass::markInvokeCallSite(InvokeInst *II, int InvokeNo, Value *CallSite, @@ -140,11 +189,15 @@ void SjLjEHPass::markInvokeCallSite(InvokeInst *II, int 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); + InvokeNo - 1); // If the unwind edge has phi nodes, split the edge. if (isa<PHINode>(II->getUnwindDest()->begin())) { - SplitCriticalEdge(II, 1, 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); // If there are any phi nodes left, they must have a single predecessor. while (PHINode *PN = dyn_cast<PHINode>(II->getUnwindDest()->begin())) { @@ -161,7 +214,12 @@ void SjLjEHPass::markInvokeCallSite(InvokeInst *II, int InvokeNo, CallInst::Create(CallSiteFn, CallSiteNoC, "", II); // Add a switch case to our unwind block. - CatchSwitch->addCase(SwitchValC, II->getUnwindDest()); + if (BasicBlock *SuccBB = LPadSuccMap[II]) { + CatchSwitch->addCase(SwitchValC, SuccBB); + } else { + CatchSwitch->addCase(SwitchValC, II->getUnwindDest()); + } + // 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. } @@ -187,10 +245,16 @@ splitLiveRangesAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes) { for (unsigned i = 0, e = Invokes.size(); i != e; ++i) { InvokeInst *II = Invokes[i]; SplitCriticalEdge(II, 0, this); - SplitCriticalEdge(II, 1, 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<PHINode>(II->getNormalDest()) && !isa<PHINode>(II->getUnwindDest()) && - "critical edge splitting left single entry phi nodes?"); + "Critical edge splitting left single entry phi nodes?"); } Function *F = Invokes.back()->getParent()->getParent(); @@ -204,7 +268,7 @@ splitLiveRangesAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes) { ++AfterAllocaInsertPt; for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end(); AI != E; ++AI) { - const Type *Ty = AI->getType(); + 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. @@ -283,9 +347,8 @@ splitLiveRangesAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes) { bool NeedsSpill = false; for (unsigned i = 0, e = Invokes.size(); i != e; ++i) { BasicBlock *UnwindBlock = Invokes[i]->getUnwindDest(); - if (UnwindBlock != BB && LiveBBs.count(UnwindBlock)) { + if (UnwindBlock != BB && LiveBBs.count(UnwindBlock)) NeedsSpill = true; - } } // If we decided we need a spill, do it. @@ -299,6 +362,44 @@ splitLiveRangesAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes) { } } +/// 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<Instruction>(Inst->use_back()); + + if (PHINode *PN = dyn_cast<PHINode>(I)) { + ReplaceLandingPadVal(F, PN, ExnAddr, SelAddr); + if (PN->use_empty()) PN->eraseFromParent(); + continue; + } + + I->replaceUsesOfWith(Inst, CreateLandingPadLoad(F, ExnAddr, SelAddr, I)); + } +} + bool SjLjEHPass::insertSjLjEHSupport(Function &F) { SmallVector<ReturnInst*,16> Returns; SmallVector<UnwindInst*,16> Unwinds; @@ -337,10 +438,23 @@ bool SjLjEHPass::insertSjLjEHSupport(Function &F) { SmallVector<CallInst*,16> EH_Exceptions; SmallVector<Instruction*,16> JmpbufUpdatePoints; - // 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. - for (Function::iterator BB = F.begin(), E = F.end(); ++BB != E;) { + 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<InvokeInst>(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; + } + for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) { if (CallInst *CI = dyn_cast<CallInst>(I)) { if (CI->getCalledFunction() == SelectorFn) { @@ -353,6 +467,10 @@ bool SjLjEHPass::insertSjLjEHSupport(Function &F) { } } else if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) { JmpbufUpdatePoints.push_back(AI); + } else if (InvokeInst *II = dyn_cast<InvokeInst>(I)) { + // FIXME: This will be always non-NULL in the new EH. + if (LandingPadInst *LPI = II->getUnwindDest()->getLandingPadInst()) + if (!PersonalityFn) PersonalityFn = LPI->getPersonalityFn(); } } } @@ -371,6 +489,16 @@ bool SjLjEHPass::insertSjLjEHSupport(Function &F) { // invoke's. splitLiveRangesAcrossInvokes(Invokes); + + SmallVector<LandingPadInst*, 16> LandingPads; + for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) { + if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) + // FIXME: This will be always non-NULL in the new EH. + if (LandingPadInst *LPI = II->getUnwindDest()->getLandingPadInst()) + LandingPads.push_back(LPI); + } + + 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 @@ -381,27 +509,25 @@ bool SjLjEHPass::insertSjLjEHSupport(Function &F) { "fcn_context", F.begin()->begin()); Value *Idxs[2]; - const Type *Int32Ty = Type::getInt32Ty(F.getContext()); + 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, Idxs+2, - "call_site", + 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, Idxs+2, - "fc_data", + Value *FCData = GetElementPtrInst::Create(FunctionContext, Idxs, "fc_data", EntryBB->getTerminator()); Idxs[1] = ConstantInt::get(Int32Ty, 1); - Value *SelectorAddr = GetElementPtrInst::Create(FCData, Idxs, Idxs+2, + 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, Idxs+2, + Value *ExceptionAddr = GetElementPtrInst::Create(FCData, Idxs, "exception_gep", EntryBB->getTerminator()); @@ -423,13 +549,16 @@ bool SjLjEHPass::insertSjLjEHSupport(Function &F) { // instruction hasn't already been removed. if (!I->getParent()) continue; Value *Val = new LoadInst(ExceptionAddr, "exception", true, I); - const Type *Ty = Type::getInt8PtrTy(F.getContext()); + Type *Ty = Type::getInt8PtrTy(F.getContext()); Val = CastInst::Create(Instruction::IntToPtr, Val, Ty, "", I); I->replaceAllUsesWith(Val); I->eraseFromParent(); } + 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 @@ -466,8 +595,7 @@ bool SjLjEHPass::insertSjLjEHSupport(Function &F) { Idxs[0] = Zero; Idxs[1] = ConstantInt::get(Int32Ty, 4); Value *LSDAFieldPtr = - GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, - "lsda_gep", + GetElementPtrInst::Create(FunctionContext, Idxs, "lsda_gep", EntryBB->getTerminator()); Value *LSDA = CallInst::Create(LSDAAddrFn, "lsda_addr", EntryBB->getTerminator()); @@ -475,8 +603,7 @@ bool SjLjEHPass::insertSjLjEHSupport(Function &F) { Idxs[1] = ConstantInt::get(Int32Ty, 3); Value *PersonalityFieldPtr = - GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, - "lsda_gep", + GetElementPtrInst::Create(FunctionContext, Idxs, "lsda_gep", EntryBB->getTerminator()); new StoreInst(PersonalityFn, PersonalityFieldPtr, true, EntryBB->getTerminator()); @@ -484,12 +611,11 @@ bool SjLjEHPass::insertSjLjEHSupport(Function &F) { // Save the frame pointer. Idxs[1] = ConstantInt::get(Int32Ty, 5); Value *JBufPtr - = GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2, - "jbuf_gep", + = GetElementPtrInst::Create(FunctionContext, Idxs, "jbuf_gep", EntryBB->getTerminator()); Idxs[1] = ConstantInt::get(Int32Ty, 0); Value *FramePtr = - GetElementPtrInst::Create(JBufPtr, Idxs, Idxs+2, "jbuf_fp_gep", + GetElementPtrInst::Create(JBufPtr, Idxs, "jbuf_fp_gep", EntryBB->getTerminator()); Value *Val = CallInst::Create(FrameAddrFn, @@ -501,7 +627,7 @@ bool SjLjEHPass::insertSjLjEHSupport(Function &F) { // Save the stack pointer. Idxs[1] = ConstantInt::get(Int32Ty, 2); Value *StackPtr = - GetElementPtrInst::Create(JBufPtr, Idxs, Idxs+2, "jbuf_sp_gep", + GetElementPtrInst::Create(JBufPtr, Idxs, "jbuf_sp_gep", EntryBB->getTerminator()); Val = CallInst::Create(StackAddrFn, "sp", EntryBB->getTerminator()); @@ -513,7 +639,7 @@ bool SjLjEHPass::insertSjLjEHSupport(Function &F) { 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 @@ -554,6 +680,8 @@ bool SjLjEHPass::insertSjLjEHSupport(Function &F) { if (Callee != SelectorFn && Callee != ExceptionFn && !CI->doesNotThrow()) insertCallSiteStore(CI, -1, CallSite); + } else if (ResumeInst *RI = dyn_cast<ResumeInst>(I)) { + insertCallSiteStore(RI, -1, CallSite); } } @@ -582,7 +710,317 @@ bool SjLjEHPass::insertSjLjEHSupport(Function &F) { return true; } +/// setupFunctionContext - Allocate the function context on the stack and fill +/// it with all of the data that we know at this point. +Value *SjLjEHPass:: +setupFunctionContext(Function &F, ArrayRef<LandingPadInst*> 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. + unsigned Align = + TLI->getTargetData()->getPrefTypeAlignment(FunctionContextTy); + AllocaInst *FuncCtx = + new AllocaInst(FunctionContextTy, 0, Align, "fn_context", EntryBB->begin()); + + // Fill in the function context structure. + Value *Idxs[2]; + Type *Int32Ty = Type::getInt32Ty(F.getContext()); + Value *Zero = ConstantInt::get(Int32Ty, 0); + Value *One = ConstantInt::get(Int32Ty, 1); + + // Keep around a reference to the call_site field. + Idxs[0] = Zero; + Idxs[1] = One; + CallSite = GetElementPtrInst::Create(FuncCtx, Idxs, "call_site", + EntryBB->getTerminator()); + + // Reference the __data field. + Idxs[1] = ConstantInt::get(Int32Ty, 2); + Value *FCData = GetElementPtrInst::Create(FuncCtx, Idxs, "__data", + 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 exception selector comes back in context->__data[1]. + Idxs[1] = One; + Value *SelectorAddr = GetElementPtrInst::Create(FCData, Idxs, + "exn_selector_gep", + EntryBB->getTerminator()); + + for (unsigned I = 0, E = LPads.size(); I != E; ++I) { + LandingPadInst *LPI = LPads[I]; + IRBuilder<> Builder(LPI->getParent()->getFirstInsertionPt()); + + Value *ExnVal = Builder.CreateLoad(ExceptionAddr, true, "exn_val"); + ExnVal = Builder.CreateIntToPtr(ExnVal, Type::getInt8PtrTy(F.getContext())); + Value *SelVal = Builder.CreateLoad(SelectorAddr, true, "exn_selector_val"); + + Type *LPadType = LPI->getType(); + Value *LPadVal = UndefValue::get(LPadType); + LPadVal = Builder.CreateInsertValue(LPadVal, ExnVal, 0, "lpad.val"); + LPadVal = Builder.CreateInsertValue(LPadVal, SelVal, 1, "lpad.val"); + + LPI->replaceAllUsesWith(LPadVal); + } + + // Personality function + Idxs[1] = ConstantInt::get(Int32Ty, 3); + if (!PersonalityFn) + PersonalityFn = LPads[0]->getPersonalityFn(); + Value *PersonalityFieldPtr = + GetElementPtrInst::Create(FuncCtx, Idxs, "pers_fn_gep", + EntryBB->getTerminator()); + new StoreInst(PersonalityFn, PersonalityFieldPtr, true, + EntryBB->getTerminator()); + + // LSDA address + Idxs[1] = ConstantInt::get(Int32Ty, 4); + Value *LSDAFieldPtr = GetElementPtrInst::Create(FuncCtx, Idxs, "lsda_gep", + EntryBB->getTerminator()); + Value *LSDA = CallInst::Create(LSDAAddrFn, "lsda_addr", + EntryBB->getTerminator()); + new StoreInst(LSDA, LSDAFieldPtr, true, EntryBB->getTerminator()); + + return FuncCtx; +} + +/// 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 SjLjEHPass::lowerIncomingArguments(Function &F) { + BasicBlock::iterator AfterAllocaInsPt = F.begin()->begin(); + while (isa<AllocaInst>(AfterAllocaInsPt) && + isa<ConstantInt>(cast<AllocaInst>(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<StructType>(Ty) || isa<ArrayType>(Ty) || isa<VectorType>(Ty)) { + Instruction *EI = ExtractValueInst::Create(AI, 0, "", AfterAllocaInsPt); + 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", + AfterAllocaInsPt); + 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); + } + } +} + +/// lowerAcrossUnwindEdges - Find all variables which are alive across an unwind +/// edge and spill them. +void SjLjEHPass::lowerAcrossUnwindEdges(Function &F, + ArrayRef<InvokeInst*> Invokes) { + // Finally, scan the code looking for instructions with bad live ranges. + 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. + Instruction *Inst = II; + if (Inst->use_empty()) continue; + if (Inst->hasOneUse() && + cast<Instruction>(Inst->use_back())->getParent() == BB && + !isa<PHINode>(Inst->use_back())) continue; + + // If this is an alloca in the entry block, it's not a real register + // value. + if (AllocaInst *AI = dyn_cast<AllocaInst>(Inst)) + if (isa<ConstantInt>(AI->getArraySize()) && BB == F.begin()) + continue; + + // Avoid iterator invalidation by copying users to a temporary vector. + SmallVector<Instruction*, 16> Users; + for (Value::use_iterator + UI = Inst->use_begin(), E = Inst->use_end(); UI != E; ++UI) { + Instruction *User = cast<Instruction>(*UI); + if (User->getParent() != BB || isa<PHINode>(User)) + Users.push_back(User); + } + + // Find all of the blocks that this value is live in. + std::set<BasicBlock*> LiveBBs; + LiveBBs.insert(Inst->getParent()); + while (!Users.empty()) { + Instruction *U = Users.back(); + Users.pop_back(); + + if (!isa<PHINode>(U)) { + MarkBlocksLiveIn(U->getParent(), LiveBBs); + } else { + // Uses for a PHI node occur in their predecessor block. + PHINode *PN = cast<PHINode>(U); + for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) + if (PN->getIncomingValue(i) == Inst) + MarkBlocksLiveIn(PN->getIncomingBlock(i), LiveBBs); + } + } + + // Now that we know all of the blocks that this thing is live in, see if + // it includes any of the unwind locations. + bool NeedsSpill = false; + for (unsigned i = 0, e = Invokes.size(); i != e; ++i) { + BasicBlock *UnwindBlock = Invokes[i]->getUnwindDest(); + if (UnwindBlock != BB && LiveBBs.count(UnwindBlock)) { + NeedsSpill = true; + } + } + + // If we decided we need a spill, do it. + // FIXME: Spilling this way is overkill, as it forces all uses of + // 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); + } + } + } +} + +/// 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 SjLjEHPass::setupEntryBlockAndCallSites(Function &F) { + SmallVector<ReturnInst*, 16> Returns; + SmallVector<InvokeInst*, 16> Invokes; + SmallVector<LandingPadInst*, 16> 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<InvokeInst>(BB->getTerminator())) { + Invokes.push_back(II); + LPads.push_back(II->getUnwindDest()->getLandingPadInst()); + } else if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) { + Returns.push_back(RI); + } + + if (Invokes.empty()) return false; + + lowerIncomingArguments(F); + lowerAcrossUnwindEdges(F, Invokes); + + Value *FuncCtx = setupFunctionContext(F, LPads); + BasicBlock *EntryBB = F.begin(); + Type *Int32Ty = Type::getInt32Ty(F.getContext()); + + Value *Idxs[2] = { + ConstantInt::get(Int32Ty, 0), 0 + }; + + // Get a reference to the jump buffer. + Idxs[1] = ConstantInt::get(Int32Ty, 5); + Value *JBufPtr = GetElementPtrInst::Create(FuncCtx, Idxs, "jbuf_gep", + EntryBB->getTerminator()); + + // Save the frame pointer. + 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()); + + // 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()); + CallInst::Create(BuiltinSetjmpFn, SetjmpArg, "", EntryBB->getTerminator()); + + // Store a pointer to the function context so that the back-end will know + // where to look for it. + Value *FuncCtxArg = CastInst::Create(Instruction::BitCast, FuncCtx, + Type::getInt8PtrTy(F.getContext()), "", + EntryBB->getTerminator()); + CallInst::Create(FuncCtxFn, FuncCtxArg, "", EntryBB->getTerminator()); + + // 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, CallSite); + + ConstantInt *CallSiteNum = + ConstantInt::get(Type::getInt32Ty(F.getContext()), I + 1); + + // 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 (BasicBlock::iterator I = BB->begin(), end = BB->end(); I != end; ++I) + if (CallInst *CI = dyn_cast<CallInst>(I)) { + if (!CI->doesNotThrow()) + insertCallSiteStore(CI, -1, CallSite); + } else if (ResumeInst *RI = dyn_cast<ResumeInst>(I)) { + insertCallSiteStore(RI, -1, CallSite); + } + + // Register the function context and make sure it's known to not throw + CallInst *Register = CallInst::Create(RegisterFn, FuncCtx, "", + EntryBB->getTerminator()); + Register->setDoesNotThrow(); + + // 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, FuncCtx, "", Returns[I]); + + return true; +} + bool SjLjEHPass::runOnFunction(Function &F) { - bool Res = insertSjLjEHSupport(F); + bool Res = false; + if (!DisableOldSjLjEH) + Res = insertSjLjEHSupport(F); + else + Res = setupEntryBlockAndCallSites(F); return Res; } |
