void insert_function_limits(Function &F){
    
    //Functions to be inserted as pragmas
    FunctionType* funvoid = FunctionType::get(Type::getVoidTy( F.getParent()->getContext() ), false);
    
    InlineAsm* fun_begin;
    InlineAsm* fun_end;
    if (sizeof(void*)==sizeof(long long)){
        fun_begin = InlineAsm::get(funvoid, "callq\tpragma_function_begin", "", false);
        fun_end = InlineAsm::get(funvoid, "callq\tpragma_function_end", "", false);
    }
    else {
        fun_begin = InlineAsm::get(funvoid, "call\tpragma_function_begin", "", false);
        fun_end = InlineAsm::get(funvoid, "call\tpragma_function_end", "", false);
    }
    
    //In the beginning
    {
        BasicBlock& first = F.getEntryBlock();
        int preds = 0;
        for (pred_iterator pi = pred_begin(&first), pe = pred_end(&first); pi != pe; pi++){
            preds++;
        }
        if (preds > 0){
            report_fatal_error("Error: The first basic block has predecessor.\n");
            //TODO: insert a new basic block in the beginning
        }
        
        CallInst* before = CallInst::Create(fun_begin);
        before->setDoesNotThrow();
        before->insertBefore( first.getFirstNonPHI() );
    }
    
    //In the end
    for (Function::iterator bb = F.begin(), en = F.end(); bb != en; bb++){
        TerminatorInst* inst = bb->getTerminator();
        
        if ( isa<ReturnInst>(inst) ){
            CallInst* after = CallInst::Create(fun_end);
            after->setDoesNotThrow();
            //after->insertBefore( inst );
            after->insertBefore( bb->getFirstNonPHI() );
        }
    }
    
}
/// getTrapBB - create a basic block that traps. All overflowing conditions
/// branch to this block. There's only one trap block per function.
BasicBlock *BoundsChecking::getTrapBB() {
  if (TrapBB && SingleTrapBB)
    return TrapBB;

  Function *Fn = Inst->getParent()->getParent();
  BasicBlock::iterator PrevInsertPoint = Builder->GetInsertPoint();
  TrapBB = BasicBlock::Create(Fn->getContext(), "trap", Fn);
  Builder->SetInsertPoint(TrapBB);

  llvm::Value *F = Intrinsic::getDeclaration(Fn->getParent(), Intrinsic::trap);
  CallInst *TrapCall = Builder->CreateCall(F);
  TrapCall->setDoesNotReturn();
  TrapCall->setDoesNotThrow();
  TrapCall->setDebugLoc(Inst->getDebugLoc());
  Builder->CreateUnreachable();

  Builder->SetInsertPoint(PrevInsertPoint);
  return TrapBB;
}
Exemple #3
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/// 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<ReturnInst *, 16> Returns;
  SmallVector<InvokeInst *, 16> Invokes;
  SmallSetVector<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())) {
      if (Function *Callee = II->getCalledFunction())
        if (Callee->isIntrinsic() &&
            Callee->getIntrinsicID() == Intrinsic::donothing) {
          // Remove the NOP invoke.
          BranchInst::Create(II->getNormalDest(), II);
          II->eraseFromParent();
          continue;
        }

      Invokes.push_back(II);
      LPads.insert(II->getUnwindDest()->getLandingPadInst());
    } else if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) {
      Returns.push_back(RI);
    }

  if (Invokes.empty())
    return false;

  NumInvokes += Invokes.size();

  lowerIncomingArguments(F);
  lowerAcrossUnwindEdges(F, Invokes);

  Value *FuncCtx =
      setupFunctionContext(F, makeArrayRef(LPads.begin(), LPads.end()));
  BasicBlock *EntryBB = &F.front();
  IRBuilder<> Builder(EntryBB->getTerminator());

  // 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");

  Value *Val = Builder.CreateCall(FrameAddrFn, Builder.getInt32(0), "fp");
  Builder.CreateStore(Val, FramePtr, /*isVolatile=*/true);

  // Save the stack pointer.
  Value *StackPtr = Builder.CreateConstGEP2_32(doubleUnderJBufTy, JBufPtr, 0, 2,
                                               "jbuf_sp_gep");

  Val = Builder.CreateCall(StackAddrFn, {}, "sp");
  Builder.CreateStore(Val, StackPtr, /*isVolatile=*/true);

  // Call the setup_dispatch instrinsic. It fills in the rest of the jmpbuf.
  Builder.CreateCall(BuiltinSetupDispatchFn, {});

  // 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);

  // 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);

    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);
      } else if (ResumeInst *RI = dyn_cast<ResumeInst>(I)) {
        insertCallSiteStore(RI, -1);
      }

  // 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 (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<CallInst>(I)) {
        if (CI->getCalledFunction() != StackRestoreFn)
          continue;
      } else if (!isa<AllocaInst>(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, FuncCtx, "", Returns[I]);

  return true;
}
Exemple #4
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/// Attempt to merge an objc_release with a store, load, and objc_retain to form
/// an objc_storeStrong. An objc_storeStrong:
///
///   objc_storeStrong(i8** %old_ptr, i8* new_value)
///
/// is equivalent to the following IR sequence:
///
///   ; Load old value.
///   %old_value = load i8** %old_ptr               (1)
///
///   ; Increment the new value and then release the old value. This must occur
///   ; in order in case old_value releases new_value in its destructor causing
///   ; us to potentially have a dangling ptr.
///   tail call i8* @objc_retain(i8* %new_value)    (2)
///   tail call void @objc_release(i8* %old_value)  (3)
///
///   ; Store the new_value into old_ptr
///   store i8* %new_value, i8** %old_ptr           (4)
///
/// The safety of this optimization is based around the following
/// considerations:
///
///  1. We are forming the store strong at the store. Thus to perform this
///     optimization it must be safe to move the retain, load, and release to
///     (4).
///  2. We need to make sure that any re-orderings of (1), (2), (3), (4) are
///     safe.
void ObjCARCContract::tryToContractReleaseIntoStoreStrong(Instruction *Release,
                                                          inst_iterator &Iter) {
  // See if we are releasing something that we just loaded.
  auto *Load = dyn_cast<LoadInst>(GetArgRCIdentityRoot(Release));
  if (!Load || !Load->isSimple())
    return;

  // For now, require everything to be in one basic block.
  BasicBlock *BB = Release->getParent();
  if (Load->getParent() != BB)
    return;

  // First scan down the BB from Load, looking for a store of the RCIdentityRoot
  // of Load's
  StoreInst *Store =
      findSafeStoreForStoreStrongContraction(Load, Release, PA, AA);
  // If we fail, bail.
  if (!Store)
    return;

  // Then find what new_value's RCIdentity Root is.
  Value *New = GetRCIdentityRoot(Store->getValueOperand());

  // Then walk up the BB and look for a retain on New without any intervening
  // instructions which conservatively might decrement ref counts.
  Instruction *Retain =
      findRetainForStoreStrongContraction(New, Store, Release, PA);

  // If we fail, bail.
  if (!Retain)
    return;

  Changed = true;
  ++NumStoreStrongs;

  DEBUG(
      llvm::dbgs() << "    Contracting retain, release into objc_storeStrong.\n"
                   << "        Old:\n"
                   << "            Store:   " << *Store << "\n"
                   << "            Release: " << *Release << "\n"
                   << "            Retain:  " << *Retain << "\n"
                   << "            Load:    " << *Load << "\n");

  LLVMContext &C = Release->getContext();
  Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
  Type *I8XX = PointerType::getUnqual(I8X);

  Value *Args[] = { Load->getPointerOperand(), New };
  if (Args[0]->getType() != I8XX)
    Args[0] = new BitCastInst(Args[0], I8XX, "", Store);
  if (Args[1]->getType() != I8X)
    Args[1] = new BitCastInst(Args[1], I8X, "", Store);
  Constant *Decl = EP.get(ARCRuntimeEntryPointKind::StoreStrong);
  CallInst *StoreStrong = CallInst::Create(Decl, Args, "", Store);
  StoreStrong->setDoesNotThrow();
  StoreStrong->setDebugLoc(Store->getDebugLoc());

  // We can't set the tail flag yet, because we haven't yet determined
  // whether there are any escaping allocas. Remember this call, so that
  // we can set the tail flag once we know it's safe.
  StoreStrongCalls.insert(StoreStrong);

  DEBUG(llvm::dbgs() << "        New Store Strong: " << *StoreStrong << "\n");

  if (&*Iter == Store) ++Iter;
  Store->eraseFromParent();
  Release->eraseFromParent();
  EraseInstruction(Retain);
  if (Load->use_empty())
    Load->eraseFromParent();
}
Exemple #5
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/// Attempt to merge an objc_release with a store, load, and objc_retain to form
/// an objc_storeStrong. This can be a little tricky because the instructions
/// don't always appear in order, and there may be unrelated intervening
/// instructions.
void ObjCARCContract::ContractRelease(Instruction *Release,
                                      inst_iterator &Iter) {
  LoadInst *Load = dyn_cast<LoadInst>(GetObjCArg(Release));
  if (!Load || !Load->isSimple()) return;

  // For now, require everything to be in one basic block.
  BasicBlock *BB = Release->getParent();
  if (Load->getParent() != BB) return;

  // Walk down to find the store and the release, which may be in either order.
  BasicBlock::iterator I = Load, End = BB->end();
  ++I;
  AliasAnalysis::Location Loc = AA->getLocation(Load);
  StoreInst *Store = 0;
  bool SawRelease = false;
  for (; !Store || !SawRelease; ++I) {
    if (I == End)
      return;

    Instruction *Inst = I;
    if (Inst == Release) {
      SawRelease = true;
      continue;
    }

    InstructionClass Class = GetBasicInstructionClass(Inst);

    // Unrelated retains are harmless.
    if (IsRetain(Class))
      continue;

    if (Store) {
      // The store is the point where we're going to put the objc_storeStrong,
      // so make sure there are no uses after it.
      if (CanUse(Inst, Load, PA, Class))
        return;
    } else if (AA->getModRefInfo(Inst, Loc) & AliasAnalysis::Mod) {
      // We are moving the load down to the store, so check for anything
      // else which writes to the memory between the load and the store.
      Store = dyn_cast<StoreInst>(Inst);
      if (!Store || !Store->isSimple()) return;
      if (Store->getPointerOperand() != Loc.Ptr) return;
    }
  }

  Value *New = StripPointerCastsAndObjCCalls(Store->getValueOperand());

  // Walk up to find the retain.
  I = Store;
  BasicBlock::iterator Begin = BB->begin();
  while (I != Begin && GetBasicInstructionClass(I) != IC_Retain)
    --I;
  Instruction *Retain = I;
  if (GetBasicInstructionClass(Retain) != IC_Retain) return;
  if (GetObjCArg(Retain) != New) return;

  Changed = true;
  ++NumStoreStrongs;

  LLVMContext &C = Release->getContext();
  Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
  Type *I8XX = PointerType::getUnqual(I8X);

  Value *Args[] = { Load->getPointerOperand(), New };
  if (Args[0]->getType() != I8XX)
    Args[0] = new BitCastInst(Args[0], I8XX, "", Store);
  if (Args[1]->getType() != I8X)
    Args[1] = new BitCastInst(Args[1], I8X, "", Store);
  CallInst *StoreStrong =
    CallInst::Create(getStoreStrongCallee(BB->getParent()->getParent()),
                     Args, "", Store);
  StoreStrong->setDoesNotThrow();
  StoreStrong->setDebugLoc(Store->getDebugLoc());

  // We can't set the tail flag yet, because we haven't yet determined
  // whether there are any escaping allocas. Remember this call, so that
  // we can set the tail flag once we know it's safe.
  StoreStrongCalls.insert(StoreStrong);

  if (&*Iter == Store) ++Iter;
  Store->eraseFromParent();
  Release->eraseFromParent();
  EraseInstruction(Retain);
  if (Load->use_empty())
    Load->eraseFromParent();
}
static bool addBoundsChecking(Function &F, TargetLibraryInfo &TLI,
                              ScalarEvolution &SE) {
  const DataLayout &DL = F.getParent()->getDataLayout();
  ObjectSizeOffsetEvaluator ObjSizeEval(DL, &TLI, F.getContext(),
                                           /*RoundToAlign=*/true);

  // check HANDLE_MEMORY_INST in include/llvm/Instruction.def for memory
  // touching instructions
  SmallVector<std::pair<Instruction *, Value *>, 4> TrapInfo;
  for (Instruction &I : instructions(F)) {
    Value *Or = nullptr;
    BuilderTy IRB(I.getParent(), BasicBlock::iterator(&I), TargetFolder(DL));
    if (LoadInst *LI = dyn_cast<LoadInst>(&I)) {
      Or = getBoundsCheckCond(LI->getPointerOperand(), LI, DL, TLI,
                              ObjSizeEval, IRB, SE);
    } else if (StoreInst *SI = dyn_cast<StoreInst>(&I)) {
      Or = getBoundsCheckCond(SI->getPointerOperand(), SI->getValueOperand(),
                              DL, TLI, ObjSizeEval, IRB, SE);
    } else if (AtomicCmpXchgInst *AI = dyn_cast<AtomicCmpXchgInst>(&I)) {
      Or = getBoundsCheckCond(AI->getPointerOperand(), AI->getCompareOperand(),
                              DL, TLI, ObjSizeEval, IRB, SE);
    } else if (AtomicRMWInst *AI = dyn_cast<AtomicRMWInst>(&I)) {
      Or = getBoundsCheckCond(AI->getPointerOperand(), AI->getValOperand(), DL,
                              TLI, ObjSizeEval, IRB, SE);
    }
    if (Or)
      TrapInfo.push_back(std::make_pair(&I, Or));
  }

  // Create a trapping basic block on demand using a callback. Depending on
  // flags, this will either create a single block for the entire function or
  // will create a fresh block every time it is called.
  BasicBlock *TrapBB = nullptr;
  auto GetTrapBB = [&TrapBB](BuilderTy &IRB) {
    if (TrapBB && SingleTrapBB)
      return TrapBB;

    Function *Fn = IRB.GetInsertBlock()->getParent();
    // FIXME: This debug location doesn't make a lot of sense in the
    // `SingleTrapBB` case.
    auto DebugLoc = IRB.getCurrentDebugLocation();
    IRBuilder<>::InsertPointGuard Guard(IRB);
    TrapBB = BasicBlock::Create(Fn->getContext(), "trap", Fn);
    IRB.SetInsertPoint(TrapBB);

    auto *F = Intrinsic::getDeclaration(Fn->getParent(), Intrinsic::trap);
    CallInst *TrapCall = IRB.CreateCall(F, {});
    TrapCall->setDoesNotReturn();
    TrapCall->setDoesNotThrow();
    TrapCall->setDebugLoc(DebugLoc);
    IRB.CreateUnreachable();

    return TrapBB;
  };

  // Add the checks.
  for (const auto &Entry : TrapInfo) {
    Instruction *Inst = Entry.first;
    BuilderTy IRB(Inst->getParent(), BasicBlock::iterator(Inst), TargetFolder(DL));
    insertBoundsCheck(Entry.second, IRB, GetTrapBB);
  }

  return !TrapInfo.empty();
}
Exemple #7
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bool SjLjEHPass::insertSjLjEHSupport(Function &F) {
  SmallVector<ReturnInst*,16> Returns;
  SmallVector<UnwindInst*,16> Unwinds;
  SmallVector<InvokeInst*,16> Invokes;

  // 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<ReturnInst>(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<InvokeInst>(BB->getTerminator())) {
      Invokes.push_back(II);
    } else if (UnwindInst *UI = dyn_cast<UnwindInst>(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<CallInst*,16> EH_Selectors;
  SmallVector<CallInst*,16> EH_Exceptions;
  SmallVector<Instruction*,16> 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<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) {
          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<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();
      }
    }
  }

  // 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;

  // 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);


  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
  // 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);
  }

  // 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();
  }

  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)

  // 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());

  // 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());

  // 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);

  // Register the function context and make sure it's known to not throw
  CallInst *Register =
    CallInst::Create(RegisterFn, FunctionContext, "",
                     ContBlock->getTerminator());
  Register->setDoesNotThrow();

  // 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);

  // 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)) {
        // 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);
      } else if (ResumeInst *RI = dyn_cast<ResumeInst>(I)) {
        insertCallSiteStore(RI, -1, CallSite);
      }
  }

  // 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();
  }

  // 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);
  }

  // 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]);

  return true;
}
Exemple #8
0
void WasmEHPrepare::prepareEHPad(BasicBlock *BB, unsigned Index) {
  assert(BB->isEHPad() && "BB is not an EHPad!");
  IRBuilder<> IRB(BB->getContext());

  IRB.SetInsertPoint(&*BB->getFirstInsertionPt());
  // The argument to wasm.catch() is the tag for C++ exceptions, which we set to
  // 0 for this module.
  // Pseudocode: void *exn = wasm.catch(0);
  Instruction *Exn = IRB.CreateCall(CatchF, IRB.getInt32(0), "exn");
  // Replace the return value of wasm.get.exception() with the return value from
  // wasm.catch().
  auto *FPI = cast<FuncletPadInst>(BB->getFirstNonPHI());
  Instruction *GetExnCI = nullptr, *GetSelectorCI = nullptr;
  for (auto &U : FPI->uses()) {
    if (auto *CI = dyn_cast<CallInst>(U.getUser())) {
      if (CI->getCalledValue() == GetExnF)
        GetExnCI = CI;
      else if (CI->getCalledValue() == GetSelectorF)
        GetSelectorCI = CI;
    }
  }

  assert(GetExnCI && "wasm.get.exception() call does not exist");
  GetExnCI->replaceAllUsesWith(Exn);
  GetExnCI->eraseFromParent();

  // In case it is a catchpad with single catch (...) or a cleanuppad, we don't
  // need to call personality function because we don't need a selector.
  if (FPI->getNumArgOperands() == 0 ||
      (FPI->getNumArgOperands() == 1 &&
       cast<Constant>(FPI->getArgOperand(0))->isNullValue())) {
    if (GetSelectorCI) {
      assert(GetSelectorCI->use_empty() &&
             "wasm.get.ehselector() still has uses!");
      GetSelectorCI->eraseFromParent();
    }
    return;
  }
  IRB.SetInsertPoint(Exn->getNextNode());

  // This is to create a map of <landingpad EH label, landingpad index> in
  // SelectionDAGISel, which is to be used in EHStreamer to emit LSDA tables.
  // Pseudocode: wasm.landingpad.index(Index);
  IRB.CreateCall(LPadIndexF, IRB.getInt32(Index));

  // Pseudocode: __wasm_lpad_context.lpad_index = index;
  IRB.CreateStore(IRB.getInt32(Index), LPadIndexField);

  // Store LSDA address only if this catchpad belongs to a top-level
  // catchswitch. If there is another catchpad that dominates this pad, we don't
  // need to store LSDA address again, because they are the same throughout the
  // function and have been already stored before.
  // TODO Can we not store LSDA address in user function but make libcxxabi
  // compute it?
  auto *CPI = cast<CatchPadInst>(FPI);
  if (isa<ConstantTokenNone>(CPI->getCatchSwitch()->getParentPad()))
    // Pseudocode: __wasm_lpad_context.lsda = wasm.lsda();
    IRB.CreateStore(IRB.CreateCall(LSDAF), LSDAField);

  // Pseudocode: _Unwind_CallPersonality(exn);
  CallInst *PersCI =
      IRB.CreateCall(CallPersonalityF, Exn, OperandBundleDef("funclet", CPI));
  PersCI->setDoesNotThrow();

  // Pseudocode: int selector = __wasm.landingpad_context.selector;
  Instruction *Selector = IRB.CreateLoad(SelectorField, "selector");

  // Replace the return value from wasm.get.ehselector() with the selector value
  // loaded from __wasm_lpad_context.selector.
  assert(GetSelectorCI && "wasm.get.ehselector() call does not exist");
  GetSelectorCI->replaceAllUsesWith(Selector);
  GetSelectorCI->eraseFromParent();
}
Exemple #9
0
    virtual bool runOnFunction(Function &F) {
      DEBUG(errs() << "Running on " << F.getName() << "\n");
      DEBUG(F.dump());
      Changed = false;
      BaseMap.clear();
      BoundsMap.clear();
      AbrtBB = 0;
      valid = true;

      if (!rootNode) {
        rootNode = getAnalysis<CallGraph>().getRoot();
        // No recursive functions for now.
        // In the future we may insert runtime checks for stack depth.
        for (scc_iterator<CallGraphNode*> SCCI = scc_begin(rootNode),
             E = scc_end(rootNode); SCCI != E; ++SCCI) {
          const std::vector<CallGraphNode*> &nextSCC = *SCCI;
          if (nextSCC.size() > 1 || SCCI.hasLoop()) {
            errs() << "INVALID: Recursion detected, callgraph SCC components: ";
            for (std::vector<CallGraphNode*>::const_iterator I = nextSCC.begin(),
                 E = nextSCC.end(); I != E; ++I) {
              Function *FF = (*I)->getFunction();
              if (FF) {
                errs() << FF->getName() << ", ";
                badFunctions.insert(FF);
              }
            }
            if (SCCI.hasLoop())
              errs() << "(self-loop)";
            errs() << "\n";
          }
          // we could also have recursion via function pointers, but we don't
          // allow calls to unknown functions, see runOnFunction() below
        }
      }

      BasicBlock::iterator It = F.getEntryBlock().begin();
      while (isa<AllocaInst>(It) || isa<PHINode>(It)) ++It;
      EP = &*It;

      TD = &getAnalysis<TargetData>();
      SE = &getAnalysis<ScalarEvolution>();
      PT = &getAnalysis<PointerTracking>();
      DT = &getAnalysis<DominatorTree>();

      std::vector<Instruction*> insns;

      BasicBlock *LastBB = 0;
      bool skip = false;
      for (inst_iterator I=inst_begin(F),E=inst_end(F); I != E;++I) {
        Instruction *II = &*I;
	if (II->getParent() != LastBB) {
	    LastBB = II->getParent();
	    skip = DT->getNode(LastBB) == 0;
	}
	if (skip)
	    continue;
        if (isa<LoadInst>(II) || isa<StoreInst>(II) || isa<MemIntrinsic>(II))
          insns.push_back(II);
        if (CallInst *CI = dyn_cast<CallInst>(II)) {
          Value *V = CI->getCalledValue()->stripPointerCasts();
          Function *F = dyn_cast<Function>(V);
          if (!F) {
            printLocation(CI, true);
            errs() << "Could not determine call target\n";
            valid = 0;
            continue;
          }
          if (!F->isDeclaration())
            continue;
          insns.push_back(CI);
        }
      }
      while (!insns.empty()) {
        Instruction *II = insns.back();
        insns.pop_back();
        DEBUG(dbgs() << "checking " << *II << "\n");
        if (LoadInst *LI = dyn_cast<LoadInst>(II)) {
          const Type *Ty = LI->getType();
          valid &= validateAccess(LI->getPointerOperand(),
                                  TD->getTypeAllocSize(Ty), LI);
        } else if (StoreInst *SI = dyn_cast<StoreInst>(II)) {
          const Type *Ty = SI->getOperand(0)->getType();
          valid &= validateAccess(SI->getPointerOperand(),
                                  TD->getTypeAllocSize(Ty), SI);
        } else if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(II)) {
          valid &= validateAccess(MI->getDest(), MI->getLength(), MI);
          if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI)) {
            valid &= validateAccess(MTI->getSource(), MI->getLength(), MI);
          }
        } else if (CallInst *CI = dyn_cast<CallInst>(II)) {
          Value *V = CI->getCalledValue()->stripPointerCasts();
          Function *F = cast<Function>(V);
          const FunctionType *FTy = F->getFunctionType();
	  CallSite CS(CI);

          if (F->getName().equals("memcmp") && FTy->getNumParams() == 3) {
            valid &= validateAccess(CS.getArgument(0), CS.getArgument(2), CI);
            valid &= validateAccess(CS.getArgument(1), CS.getArgument(2), CI);
            continue;
          }
	  unsigned i;
#ifdef CLAMBC_COMPILER
	  i = 0;
#else
	  i = 1;// skip hidden ctx*
#endif
          for (;i<FTy->getNumParams();i++) {
            if (isa<PointerType>(FTy->getParamType(i))) {
              Value *Ptr = CS.getArgument(i);
              if (i+1 >= FTy->getNumParams()) {
                printLocation(CI, false);
                errs() << "Call to external function with pointer parameter last cannot be analyzed\n";
                errs() << *CI << "\n";
                valid = 0;
                break;
              }
              Value *Size = CS.getArgument(i+1);
              if (!Size->getType()->isIntegerTy()) {
                printLocation(CI, false);
                errs() << "Pointer argument must be followed by integer argument representing its size\n";
                errs() << *CI << "\n";
                valid = 0;
                break;
              }
              valid &= validateAccess(Ptr, Size, CI);
            }
          }
        }
      }
      if (badFunctions.count(&F))
        valid = 0;

      if (!valid) {
	DEBUG(F.dump());
        ClamBCModule::stop("Verification found errors!", &F);
	// replace function with call to abort
        std::vector<const Type*>args;
        FunctionType* abrtTy = FunctionType::get(
          Type::getVoidTy(F.getContext()),args,false);
        Constant *func_abort =
          F.getParent()->getOrInsertFunction("abort", abrtTy);

	BasicBlock *BB = &F.getEntryBlock();
	Instruction *I = &*BB->begin();
	Instruction *UI = new UnreachableInst(F.getContext(), I);
	CallInst *AbrtC = CallInst::Create(func_abort, "", UI);
        AbrtC->setCallingConv(CallingConv::C);
        AbrtC->setTailCall(true);
        AbrtC->setDoesNotReturn(true);
        AbrtC->setDoesNotThrow(true);
	// remove all instructions from entry
	BasicBlock::iterator BBI = I, BBE=BB->end();
	while (BBI != BBE) {
	    if (!BBI->use_empty())
		BBI->replaceAllUsesWith(UndefValue::get(BBI->getType()));
	    BB->getInstList().erase(BBI++);
	}
      }
      return Changed;
    }