Esempio n. 1
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void GraphBuilder::visitLoadInst(LoadInst &LI) {
  //
  // Create a DSNode for the pointer dereferenced by the load.  If the DSNode
  // is NULL, do nothing more (this can occur if the load is loading from a
  // NULL pointer constant (bugpoint can generate such code).
  //
  DSNodeHandle Ptr = getValueDest(LI.getPointerOperand());
  if (Ptr.isNull()) return; // Load from null

  // Make that the node is read from...
  Ptr.getNode()->setReadMarker();

  // Ensure a typerecord exists...
  Ptr.getNode()->growSizeForType(LI.getType(), Ptr.getOffset());

  if (isa<PointerType>(LI.getType()))
    setDestTo(LI, getLink(Ptr));

  // check that it is the inserted value
  if(TypeInferenceOptimize)
    if(LI.hasOneUse())
      if(StoreInst *SI = dyn_cast<StoreInst>(*(LI.use_begin())))
        if(SI->getOperand(0) == &LI) {
        ++NumIgnoredInst;
        return;
      }
  Ptr.getNode()->mergeTypeInfo(LI.getType(), Ptr.getOffset());
}
/// RewriteSingleStoreAlloca - If there is only a single store to this value,
/// replace any loads of it that are directly dominated by the definition with
/// the value stored.
void PromoteMem2Reg::RewriteSingleStoreAlloca(AllocaInst *AI,
                                              AllocaInfo &Info,
                                              LargeBlockInfo &LBI) {
  StoreInst *OnlyStore = Info.OnlyStore;
  bool StoringGlobalVal = !isa<Instruction>(OnlyStore->getOperand(0));
  BasicBlock *StoreBB = OnlyStore->getParent();
  int StoreIndex = -1;

  // Clear out UsingBlocks.  We will reconstruct it here if needed.
  Info.UsingBlocks.clear();
  
  for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end(); UI != E; ) {
    Instruction *UserInst = cast<Instruction>(*UI++);
    if (!isa<LoadInst>(UserInst)) {
      assert(UserInst == OnlyStore && "Should only have load/stores");
      continue;
    }
    LoadInst *LI = cast<LoadInst>(UserInst);
    
    // Okay, if we have a load from the alloca, we want to replace it with the
    // only value stored to the alloca.  We can do this if the value is
    // dominated by the store.  If not, we use the rest of the mem2reg machinery
    // to insert the phi nodes as needed.
    if (!StoringGlobalVal) {  // Non-instructions are always dominated.
      if (LI->getParent() == StoreBB) {
        // If we have a use that is in the same block as the store, compare the
        // indices of the two instructions to see which one came first.  If the
        // load came before the store, we can't handle it.
        if (StoreIndex == -1)
          StoreIndex = LBI.getInstructionIndex(OnlyStore);

        if (unsigned(StoreIndex) > LBI.getInstructionIndex(LI)) {
          // Can't handle this load, bail out.
          Info.UsingBlocks.push_back(StoreBB);
          continue;
        }
        
      } else if (LI->getParent() != StoreBB &&
                 !dominates(StoreBB, LI->getParent())) {
        // If the load and store are in different blocks, use BB dominance to
        // check their relationships.  If the store doesn't dom the use, bail
        // out.
        Info.UsingBlocks.push_back(LI->getParent());
        continue;
      }
    }
    
    // Otherwise, we *can* safely rewrite this load.
    Value *ReplVal = OnlyStore->getOperand(0);
    // If the replacement value is the load, this must occur in unreachable
    // code.
    if (ReplVal == LI)
      ReplVal = UndefValue::get(LI->getType());
    LI->replaceAllUsesWith(ReplVal);
    if (AST && LI->getType()->isPointerTy())
      AST->deleteValue(LI);
    LI->eraseFromParent();
    LBI.deleteValue(LI);
  }
}
Esempio n. 3
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/// MoveExtToFormExtLoad - Move a zext or sext fed by a load into the same
/// basic block as the load, unless conditions are unfavorable. This allows
/// SelectionDAG to fold the extend into the load.
///
bool CodeGenPrepare::MoveExtToFormExtLoad(Instruction *I) {
    // Look for a load being extended.
    LoadInst *LI = dyn_cast<LoadInst>(I->getOperand(0));
    if (!LI) return false;

    // If they're already in the same block, there's nothing to do.
    if (LI->getParent() == I->getParent())
        return false;

    // If the load has other users and the truncate is not free, this probably
    // isn't worthwhile.
    if (!LI->hasOneUse() &&
            TLI && (TLI->isTypeLegal(TLI->getValueType(LI->getType())) ||
                    !TLI->isTypeLegal(TLI->getValueType(I->getType()))) &&
            !TLI->isTruncateFree(I->getType(), LI->getType()))
        return false;

    // Check whether the target supports casts folded into loads.
    unsigned LType;
    if (isa<ZExtInst>(I))
        LType = ISD::ZEXTLOAD;
    else {
        assert(isa<SExtInst>(I) && "Unexpected ext type!");
        LType = ISD::SEXTLOAD;
    }
    if (TLI && !TLI->isLoadExtLegal(LType, TLI->getValueType(LI->getType())))
        return false;

    // Move the extend into the same block as the load, so that SelectionDAG
    // can fold it.
    I->removeFromParent();
    I->insertAfter(LI);
    ++NumExtsMoved;
    return true;
}
void InstrumentMemoryAccesses::visitLoadInst(LoadInst &LI) {
  // Instrument a load instruction with a load check.
  Value *AccessSize = ConstantInt::get(SizeTy,
                                       TD->getTypeStoreSize(LI.getType()));
  instrument(LI.getPointerOperand(), AccessSize, LoadCheckFunction, LI);
  ++LoadsInstrumented;
}
Esempio n. 5
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void Interpreter::visitLoadInst(LoadInst &I) {
  ExecutionContext &SF = ECStack.back();
  GenericValue SRC = getOperandValue(I.getPointerOperand(), SF);
  GenericValue *Ptr = (GenericValue*)GVTOP(SRC);
  GenericValue Result = LoadValueFromMemory(Ptr, I.getType());
  SetValue(&I, Result, SF);
}
bool AMDGPUCodeGenPrepare::visitLoadInst(LoadInst &I) {
  if (!WidenLoads)
    return false;

  if ((I.getPointerAddressSpace() == AMDGPUASI.CONSTANT_ADDRESS ||
       I.getPointerAddressSpace() == AMDGPUASI.CONSTANT_ADDRESS_32BIT) &&
      canWidenScalarExtLoad(I)) {
    IRBuilder<> Builder(&I);
    Builder.SetCurrentDebugLocation(I.getDebugLoc());

    Type *I32Ty = Builder.getInt32Ty();
    Type *PT = PointerType::get(I32Ty, I.getPointerAddressSpace());
    Value *BitCast= Builder.CreateBitCast(I.getPointerOperand(), PT);
    LoadInst *WidenLoad = Builder.CreateLoad(BitCast);
    WidenLoad->copyMetadata(I);

    // If we have range metadata, we need to convert the type, and not make
    // assumptions about the high bits.
    if (auto *Range = WidenLoad->getMetadata(LLVMContext::MD_range)) {
      ConstantInt *Lower =
        mdconst::extract<ConstantInt>(Range->getOperand(0));

      if (Lower->getValue().isNullValue()) {
        WidenLoad->setMetadata(LLVMContext::MD_range, nullptr);
      } else {
        Metadata *LowAndHigh[] = {
          ConstantAsMetadata::get(ConstantInt::get(I32Ty, Lower->getValue().zext(32))),
          // Don't make assumptions about the high bits.
          ConstantAsMetadata::get(ConstantInt::get(I32Ty, 0))
        };

        WidenLoad->setMetadata(LLVMContext::MD_range,
                               MDNode::get(Mod->getContext(), LowAndHigh));
      }
    }

    int TySize = Mod->getDataLayout().getTypeSizeInBits(I.getType());
    Type *IntNTy = Builder.getIntNTy(TySize);
    Value *ValTrunc = Builder.CreateTrunc(WidenLoad, IntNTy);
    Value *ValOrig = Builder.CreateBitCast(ValTrunc, I.getType());
    I.replaceAllUsesWith(ValOrig);
    I.eraseFromParent();
    return true;
  }

  return false;
}
void PropagateJuliaAddrspaces::visitLoadInst(LoadInst &LI) {
    unsigned AS = LI.getPointerAddressSpace();
    if (!isSpecialAS(AS))
        return;
    Value *Replacement = LiftPointer(LI.getPointerOperand(), LI.getType(), &LI);
    if (!Replacement)
        return;
    LI.setOperand(LoadInst::getPointerOperandIndex(), Replacement);
}
bool AMDGPUCodeGenPrepare::canWidenScalarExtLoad(LoadInst &I) const {
  Type *Ty = I.getType();
  const DataLayout &DL = Mod->getDataLayout();
  int TySize = DL.getTypeSizeInBits(Ty);
  unsigned Align = I.getAlignment() ?
                   I.getAlignment() : DL.getABITypeAlignment(Ty);

  return I.isSimple() && TySize < 32 && Align >= 4 && DA->isUniform(&I);
}
Esempio n. 9
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void LLSTDebuggingPass::insertLoadInstCheck(Function& F)
{
    Value* BrokenPointerMessage = m_builder->CreateGlobalStringPtr("\npointer is broken\n");

    InstructionVector Loads;
    for (Function::iterator BB = F.begin(); BB != F.end(); ++BB)
    {
        for(BasicBlock::iterator II = BB->begin(); II != BB->end(); ++II)
        {
            if (LoadInst* Load = dyn_cast<LoadInst>(II)) {
                Loads.push_back(Load);
            }
        }
    }

    for(std::size_t i = 0; i < Loads.size(); i++)
    {
        LoadInst* Load = dyn_cast<LoadInst>(Loads[i]);
        if (belongsToSmalltalkType( Load->getType() )) {

            //split BB right after load inst. The new BB contains code that will be executed if pointer is OK
            BasicBlock* PointerIsOkBB = Load->getParent()->splitBasicBlock(++( static_cast<BasicBlock::iterator>(Load) ));
            BasicBlock* PointerIsBrokenBB = BasicBlock::Create(m_module->getContext(), "", &F, PointerIsOkBB);
            BasicBlock* PointerIsNotSmallIntBB = BasicBlock::Create(m_module->getContext(), "", &F, PointerIsBrokenBB);

            Instruction* branchToPointerIsOkBB = ++( static_cast<BasicBlock::iterator>(Load) );
            //branchToPointerIsOkBB is created by splitBasicBlock() just after load inst
            //We force builder to insert instructions before branchToPointerIsOkBB
            m_builder->SetInsertPoint(branchToPointerIsOkBB);

            //If pointer to class is null, jump to PointerIsBroken, otherwise to PointerIsOkBB
            Value* objectPtr = m_builder->CreateBitCast( Load, m_baseTypes.object->getPointerTo());

            Value* isSmallInt = m_builder->CreateCall(isSmallInteger, objectPtr);
            m_builder->CreateCondBr(isSmallInt, PointerIsOkBB, PointerIsNotSmallIntBB);

            m_builder->SetInsertPoint(PointerIsNotSmallIntBB);
            Value* klassPtr = m_builder->CreateCall(getObjectClass, objectPtr);
            Value* pointerIsNull = m_builder->CreateICmpEQ(klassPtr, ConstantPointerNull::get(m_baseTypes.klass->getPointerTo()) );
            m_builder->CreateCondBr(pointerIsNull, PointerIsBrokenBB, PointerIsOkBB);

            branchToPointerIsOkBB->eraseFromParent(); //We don't need it anymore

            m_builder->SetInsertPoint(PointerIsBrokenBB);
            m_builder->CreateCall(_printf, BrokenPointerMessage);
            m_builder->CreateBr(PointerIsOkBB);
        }
    }
}
void GCInvariantVerifier::visitLoadInst(LoadInst &LI) {
    Type *Ty = LI.getType();
    if (Ty->isPointerTy()) {
        unsigned AS = cast<PointerType>(Ty)->getAddressSpace();
        Check(AS != AddressSpace::CalleeRooted &&
              AS != AddressSpace::Derived,
              "Illegal load of gc relevant value", &LI);
    }
    Ty = LI.getPointerOperand()->getType();
    if (Ty->isPointerTy()) {
        unsigned AS = cast<PointerType>(Ty)->getAddressSpace();
        Check(AS != AddressSpace::CalleeRooted,
              "Illegal store of callee rooted value", &LI);
    }
}
Esempio n. 11
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bool IRTranslator::translateLoad(const LoadInst &LI) {
  assert(LI.isSimple() && "only simple loads are supported at the moment");

  MachineFunction &MF = MIRBuilder.getMF();
  unsigned Res = getOrCreateVReg(LI);
  unsigned Addr = getOrCreateVReg(*LI.getPointerOperand());
  LLT VTy{*LI.getType()}, PTy{*LI.getPointerOperand()->getType()};

  MIRBuilder.buildLoad(
      VTy, PTy, Res, Addr,
      *MF.getMachineMemOperand(MachinePointerInfo(LI.getPointerOperand()),
                               MachineMemOperand::MOLoad,
                               VTy.getSizeInBits() / 8, getMemOpAlignment(LI)));
  return true;
}
Esempio n. 12
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void ArrayIndexChecker::visitLoadInst(LoadInst& I) {
  DEBUG(dbgs() << "ArrayIndexChecker: visiting load " << I << "\n");

  visitValue(*I.getPointerOperand());

  if (I.getType()->isPointerTy()) {
    auto pos = std::find(ptr_value_vec_.begin(), ptr_value_vec_.end(), &I);
    assert(pos != ptr_value_vec_.end());
    index_t varIdx = pos - ptr_value_vec_.begin();

    assert(idx2addr_.find(varIdx) != idx2addr_.end());
    if (addr2version_[idx2addr_[varIdx]] != 0)
      throw ArrayIndexIsNotConstant;
  }
  DEBUG(dbgs() << "ArrayIndexChecker: visited load\n");
}
Esempio n. 13
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void TracingNoGiri::visitLoadInst(LoadInst &LI) {
  instrumentLock(&LI);

  // Get the ID of the load instruction.
  Value *LoadID = ConstantInt::get(Int32Type, lsNumPass->getID(&LI));
  // Cast the pointer into a void pointer type.
  Value *Pointer = LI.getPointerOperand();
  Pointer = castTo(Pointer, VoidPtrType, Pointer->getName(), &LI);
  // Get the size of the loaded data.
  uint64_t size = TD->getTypeStoreSize(LI.getType());
  Value *LoadSize = ConstantInt::get(Int64Type, size);
  // Create the call to the run-time to record the load instruction.
  std::vector<Value *> args=make_vector<Value *>(LoadID, Pointer, LoadSize, 0);
  CallInst::Create(RecordLoad, args, "", &LI);

  instrumentUnlock(&LI);
  ++NumLoads; // Update statistics
}
Esempio n. 14
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void SanitizerCoverageModule::InjectCoverageAtBlock(Function &F,
                                                    BasicBlock &BB) {
  BasicBlock::iterator IP = BB.getFirstInsertionPt(), BE = BB.end();
  // Skip static allocas at the top of the entry block so they don't become
  // dynamic when we split the block.  If we used our optimized stack layout,
  // then there will only be one alloca and it will come first.
  for (; IP != BE; ++IP) {
    AllocaInst *AI = dyn_cast<AllocaInst>(IP);
    if (!AI || !AI->isStaticAlloca())
      break;
  }

  bool IsEntryBB = &BB == &F.getEntryBlock();
  DebugLoc EntryLoc =
      IsEntryBB ? IP->getDebugLoc().getFnDebugLoc(*C) : IP->getDebugLoc();
  IRBuilder<> IRB(IP);
  IRB.SetCurrentDebugLocation(EntryLoc);
  SmallVector<Value *, 1> Indices;
  Value *GuardP = IRB.CreateAdd(
      IRB.CreatePointerCast(GuardArray, IntptrTy),
      ConstantInt::get(IntptrTy, (1 + SanCovFunction->getNumUses()) * 4));
  Type *Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
  GuardP = IRB.CreateIntToPtr(GuardP, Int32PtrTy);
  LoadInst *Load = IRB.CreateLoad(GuardP);
  Load->setAtomic(Monotonic);
  Load->setAlignment(4);
  Load->setMetadata(F.getParent()->getMDKindID("nosanitize"),
                    MDNode::get(*C, None));
  Value *Cmp = IRB.CreateICmpSGE(Constant::getNullValue(Load->getType()), Load);
  Instruction *Ins = SplitBlockAndInsertIfThen(
      Cmp, IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
  IRB.SetInsertPoint(Ins);
  IRB.SetCurrentDebugLocation(EntryLoc);
  // __sanitizer_cov gets the PC of the instruction using GET_CALLER_PC.
  IRB.CreateCall(SanCovFunction, GuardP);
  IRB.CreateCall(EmptyAsm);  // Avoids callback merge.

  if (ClExperimentalTracing) {
    // Experimental support for tracing.
    // Insert a callback with the same guard variable as used for coverage.
    IRB.SetInsertPoint(IP);
    IRB.CreateCall(IsEntryBB ? SanCovTraceEnter : SanCovTraceBB, GuardP);
  }
}
Esempio n. 15
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void Closure::unpack_struct(Scope<Value *> &dst,
                            Value *src,
                            IRBuilder<> *builder) {
    // src should be a pointer to a struct of the type returned by build_type
    int idx = 0;
    LLVMContext &context = builder->getContext();
    vector<string> nm = names();
    for (size_t i = 0; i < nm.size(); i++) {
        Value *ptr = builder->CreateConstInBoundsGEP2_32(src, 0, idx++);
        LoadInst *load = builder->CreateLoad(ptr);
        if (load->getType()->isPointerTy()) {
            // Give it a unique type so that tbaa tells llvm that this can't alias anything
            load->setMetadata("tbaa", MDNode::get(context,
                                                  vec<Value *>(MDString::get(context, nm[i]))));
        }
        dst.push(nm[i], load);
        load->setName(nm[i]);
    }
}
Esempio n. 16
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/// Try to fold load I.
bool UnrolledInstAnalyzer::visitLoad(LoadInst &I) {
  Value *AddrOp = I.getPointerOperand();

  auto AddressIt = SimplifiedAddresses.find(AddrOp);
  if (AddressIt == SimplifiedAddresses.end())
    return false;
  ConstantInt *SimplifiedAddrOp = AddressIt->second.Offset;

  auto *GV = dyn_cast<GlobalVariable>(AddressIt->second.Base);
  // We're only interested in loads that can be completely folded to a
  // constant.
  if (!GV || !GV->hasDefinitiveInitializer() || !GV->isConstant())
    return false;

  ConstantDataSequential *CDS =
      dyn_cast<ConstantDataSequential>(GV->getInitializer());
  if (!CDS)
    return false;

  // We might have a vector load from an array. FIXME: for now we just bail
  // out in this case, but we should be able to resolve and simplify such
  // loads.
  if(!CDS->isElementTypeCompatible(I.getType()))
    return false;

  int ElemSize = CDS->getElementType()->getPrimitiveSizeInBits() / 8U;
  if (SimplifiedAddrOp->getValue().getActiveBits() >= 64)
    return false;
  int64_t Index = SimplifiedAddrOp->getSExtValue() / ElemSize;
  if (Index >= CDS->getNumElements()) {
    // FIXME: For now we conservatively ignore out of bound accesses, but
    // we're allowed to perform the optimization in this case.
    return false;
  }

  Constant *CV = CDS->getElementAsConstant(Index);
  assert(CV && "Constant expected.");
  SimplifiedValues[&I] = CV;

  return true;
}
Esempio n. 17
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bool Scalarizer::visitLoadInst(LoadInst &LI) {
  if (!ScalarizeLoadStore)
    return false;
  if (!LI.isSimple())
    return false;

  VectorLayout Layout;
  if (!getVectorLayout(LI.getType(), LI.getAlignment(), Layout))
    return false;

  unsigned NumElems = Layout.VecTy->getNumElements();
  IRBuilder<> Builder(LI.getParent(), &LI);
  Scatterer Ptr = scatter(&LI, LI.getPointerOperand());
  ValueVector Res;
  Res.resize(NumElems);

  for (unsigned I = 0; I < NumElems; ++I)
    Res[I] = Builder.CreateAlignedLoad(Ptr[I], Layout.getElemAlign(I),
                                       LI.getName() + ".i" + Twine(I));
  gather(&LI, Res);
  return true;
}
Esempio n. 18
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File: LICM.cpp Progetto: aaasz/SHP
/// PromoteValuesInLoop - Try to promote memory values to scalars by sinking
/// stores out of the loop and moving loads to before the loop.  We do this by
/// looping over the stores in the loop, looking for stores to Must pointers
/// which are loop invariant.  We promote these memory locations to use allocas
/// instead.  These allocas can easily be raised to register values by the
/// PromoteMem2Reg functionality.
///
void LICM::PromoteValuesInLoop() {
  // PromotedValues - List of values that are promoted out of the loop.  Each
  // value has an alloca instruction for it, and a canonical version of the
  // pointer.
  std::vector<std::pair<AllocaInst*, Value*> > PromotedValues;
  std::map<Value*, AllocaInst*> ValueToAllocaMap; // Map of ptr to alloca

  FindPromotableValuesInLoop(PromotedValues, ValueToAllocaMap);
  if (ValueToAllocaMap.empty()) return;   // If there are values to promote.

  Changed = true;
  NumPromoted += PromotedValues.size();

  std::vector<Value*> PointerValueNumbers;

  // Emit a copy from the value into the alloca'd value in the loop preheader
  TerminatorInst *LoopPredInst = Preheader->getTerminator();
  for (unsigned i = 0, e = PromotedValues.size(); i != e; ++i) {
    Value *Ptr = PromotedValues[i].second;

    // If we are promoting a pointer value, update alias information for the
    // inserted load.
    Value *LoadValue = 0;
    if (isa<PointerType>(cast<PointerType>(Ptr->getType())->getElementType())) {
      // Locate a load or store through the pointer, and assign the same value
      // to LI as we are loading or storing.  Since we know that the value is
      // stored in this loop, this will always succeed.
      for (Value::use_iterator UI = Ptr->use_begin(), E = Ptr->use_end();
           UI != E; ++UI)
        if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) {
          LoadValue = LI;
          break;
        } else if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) {
          if (SI->getOperand(1) == Ptr) {
            LoadValue = SI->getOperand(0);
            break;
          }
        }
      assert(LoadValue && "No store through the pointer found!");
      PointerValueNumbers.push_back(LoadValue);  // Remember this for later.
    }

    // Load from the memory we are promoting.
    LoadInst *LI = new LoadInst(Ptr, Ptr->getName()+".promoted", LoopPredInst);

    if (LoadValue) CurAST->copyValue(LoadValue, LI);

    // Store into the temporary alloca.
    new StoreInst(LI, PromotedValues[i].first, LoopPredInst);
  }

  // Scan the basic blocks in the loop, replacing uses of our pointers with
  // uses of the allocas in question.
  //
  for (Loop::block_iterator I = CurLoop->block_begin(),
         E = CurLoop->block_end(); I != E; ++I) {
    BasicBlock *BB = *I;
    // Rewrite all loads and stores in the block of the pointer...
    for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ++II) {
      if (LoadInst *L = dyn_cast<LoadInst>(II)) {
        std::map<Value*, AllocaInst*>::iterator
          I = ValueToAllocaMap.find(L->getOperand(0));
        if (I != ValueToAllocaMap.end())
          L->setOperand(0, I->second);    // Rewrite load instruction...
      } else if (StoreInst *S = dyn_cast<StoreInst>(II)) {
        std::map<Value*, AllocaInst*>::iterator
          I = ValueToAllocaMap.find(S->getOperand(1));
        if (I != ValueToAllocaMap.end())
          S->setOperand(1, I->second);    // Rewrite store instruction...
      }
    }
  }

  // Now that the body of the loop uses the allocas instead of the original
  // memory locations, insert code to copy the alloca value back into the
  // original memory location on all exits from the loop.  Note that we only
  // want to insert one copy of the code in each exit block, though the loop may
  // exit to the same block more than once.
  //
  SmallPtrSet<BasicBlock*, 16> ProcessedBlocks;

  SmallVector<BasicBlock*, 8> ExitBlocks;
  CurLoop->getExitBlocks(ExitBlocks);
  for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) {
    if (!ProcessedBlocks.insert(ExitBlocks[i]))
      continue;
  
    // Copy all of the allocas into their memory locations.
    BasicBlock::iterator BI = ExitBlocks[i]->getFirstNonPHI();
    Instruction *InsertPos = BI;
    unsigned PVN = 0;
    for (unsigned i = 0, e = PromotedValues.size(); i != e; ++i) {
      // Load from the alloca.
      LoadInst *LI = new LoadInst(PromotedValues[i].first, "", InsertPos);

      // If this is a pointer type, update alias info appropriately.
      if (isa<PointerType>(LI->getType()))
        CurAST->copyValue(PointerValueNumbers[PVN++], LI);

      // Store into the memory we promoted.
      new StoreInst(LI, PromotedValues[i].second, InsertPos);
    }
  }

  // Now that we have done the deed, use the mem2reg functionality to promote
  // all of the new allocas we just created into real SSA registers.
  //
  std::vector<AllocaInst*> PromotedAllocas;
  PromotedAllocas.reserve(PromotedValues.size());
  for (unsigned i = 0, e = PromotedValues.size(); i != e; ++i)
    PromotedAllocas.push_back(PromotedValues[i].first);
  PromoteMemToReg(PromotedAllocas, *DT, *DF, CurAST);
}
/// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible.
static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI,
                                        const DataLayout *DL) {
  User *CI = cast<User>(LI.getOperand(0));
  Value *CastOp = CI->getOperand(0);

  PointerType *DestTy = cast<PointerType>(CI->getType());
  Type *DestPTy = DestTy->getElementType();
  if (PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {

    // If the address spaces don't match, don't eliminate the cast.
    if (DestTy->getAddressSpace() != SrcTy->getAddressSpace())
      return nullptr;

    Type *SrcPTy = SrcTy->getElementType();

    if (DestPTy->isIntegerTy() || DestPTy->isPointerTy() ||
         DestPTy->isVectorTy()) {
      // If the source is an array, the code below will not succeed.  Check to
      // see if a trivial 'gep P, 0, 0' will help matters.  Only do this for
      // constants.
      if (ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
        if (Constant *CSrc = dyn_cast<Constant>(CastOp))
          if (ASrcTy->getNumElements() != 0) {
            Type *IdxTy = DL
                        ? DL->getIntPtrType(SrcTy)
                        : Type::getInt64Ty(SrcTy->getContext());
            Value *Idx = Constant::getNullValue(IdxTy);
            Value *Idxs[2] = { Idx, Idx };
            CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
            SrcTy = cast<PointerType>(CastOp->getType());
            SrcPTy = SrcTy->getElementType();
          }

      if (IC.getDataLayout() &&
          (SrcPTy->isIntegerTy() || SrcPTy->isPointerTy() ||
            SrcPTy->isVectorTy()) &&
          // Do not allow turning this into a load of an integer, which is then
          // casted to a pointer, this pessimizes pointer analysis a lot.
          (SrcPTy->isPtrOrPtrVectorTy() ==
           LI.getType()->isPtrOrPtrVectorTy()) &&
          IC.getDataLayout()->getTypeSizeInBits(SrcPTy) ==
               IC.getDataLayout()->getTypeSizeInBits(DestPTy)) {

        // Okay, we are casting from one integer or pointer type to another of
        // the same size.  Instead of casting the pointer before the load, cast
        // the result of the loaded value.
        LoadInst *NewLoad =
          IC.Builder->CreateLoad(CastOp, LI.isVolatile(), CI->getName());
        NewLoad->setAlignment(LI.getAlignment());
        NewLoad->setAtomic(LI.getOrdering(), LI.getSynchScope());
        // Now cast the result of the load.
        PointerType *OldTy = dyn_cast<PointerType>(NewLoad->getType());
        PointerType *NewTy = dyn_cast<PointerType>(LI.getType());
        if (OldTy && NewTy &&
            OldTy->getAddressSpace() != NewTy->getAddressSpace()) {
          return new AddrSpaceCastInst(NewLoad, LI.getType());
        }

        return new BitCastInst(NewLoad, LI.getType());
      }
    }
  }
  return nullptr;
}
Esempio n. 20
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bool NVPTXLowerAggrCopies::runOnFunction(Function &F) {
  SmallVector<LoadInst *, 4> aggrLoads;
  SmallVector<MemTransferInst *, 4> aggrMemcpys;
  SmallVector<MemSetInst *, 4> aggrMemsets;

  DataLayout *TD = &getAnalysis<DataLayout>();
  LLVMContext &Context = F.getParent()->getContext();

  //
  // Collect all the aggrLoads, aggrMemcpys and addrMemsets.
  //
  //const BasicBlock *firstBB = &F.front();  // first BB in F
  for (Function::iterator BI = F.begin(), BE = F.end(); BI != BE; ++BI) {
    //BasicBlock *bb = BI;
    for (BasicBlock::iterator II = BI->begin(), IE = BI->end(); II != IE;
        ++II) {
      if (LoadInst * load = dyn_cast<LoadInst>(II)) {

        if (load->hasOneUse() == false) continue;

        if (TD->getTypeStoreSize(load->getType()) < MaxAggrCopySize) continue;

        User *use = *(load->use_begin());
        if (StoreInst * store = dyn_cast<StoreInst>(use)) {
          if (store->getOperand(0) != load) //getValueOperand
          continue;
          aggrLoads.push_back(load);
        }
      } else if (MemTransferInst * intr = dyn_cast<MemTransferInst>(II)) {
        Value *len = intr->getLength();
        // If the number of elements being copied is greater
        // than MaxAggrCopySize, lower it to a loop
        if (ConstantInt * len_int = dyn_cast < ConstantInt > (len)) {
          if (len_int->getZExtValue() >= MaxAggrCopySize) {
            aggrMemcpys.push_back(intr);
          }
        } else {
          // turn variable length memcpy/memmov into loop
          aggrMemcpys.push_back(intr);
        }
      } else if (MemSetInst * memsetintr = dyn_cast<MemSetInst>(II)) {
        Value *len = memsetintr->getLength();
        if (ConstantInt * len_int = dyn_cast<ConstantInt>(len)) {
          if (len_int->getZExtValue() >= MaxAggrCopySize) {
            aggrMemsets.push_back(memsetintr);
          }
        } else {
          // turn variable length memset into loop
          aggrMemsets.push_back(memsetintr);
        }
      }
    }
  }
  if ((aggrLoads.size() == 0) && (aggrMemcpys.size() == 0)
      && (aggrMemsets.size() == 0)) return false;

  //
  // Do the transformation of an aggr load/copy/set to a loop
  //
  for (unsigned i = 0, e = aggrLoads.size(); i != e; ++i) {
    LoadInst *load = aggrLoads[i];
    StoreInst *store = dyn_cast<StoreInst>(*load->use_begin());
    Value *srcAddr = load->getOperand(0);
    Value *dstAddr = store->getOperand(1);
    unsigned numLoads = TD->getTypeStoreSize(load->getType());
    Value *len = ConstantInt::get(Type::getInt32Ty(Context), numLoads);

    convertTransferToLoop(store, srcAddr, dstAddr, len, load->isVolatile(),
                          store->isVolatile(), Context, F);

    store->eraseFromParent();
    load->eraseFromParent();
  }

  for (unsigned i = 0, e = aggrMemcpys.size(); i != e; ++i) {
    MemTransferInst *cpy = aggrMemcpys[i];
    Value *len = cpy->getLength();
    // llvm 2.7 version of memcpy does not have volatile
    // operand yet. So always making it non-volatile
    // optimistically, so that we don't see unnecessary
    // st.volatile in ptx
    convertTransferToLoop(cpy, cpy->getSource(), cpy->getDest(), len, false,
                          false, Context, F);
    cpy->eraseFromParent();
  }

  for (unsigned i = 0, e = aggrMemsets.size(); i != e; ++i) {
    MemSetInst *memsetinst = aggrMemsets[i];
    Value *len = memsetinst->getLength();
    Value *val = memsetinst->getValue();
    convertMemSetToLoop(memsetinst, memsetinst->getDest(), len, val, Context,
                        F);
    memsetinst->eraseFromParent();
  }

  return true;
}
Esempio n. 21
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/// Many allocas are only used within a single basic block.  If this is the
/// case, avoid traversing the CFG and inserting a lot of potentially useless
/// PHI nodes by just performing a single linear pass over the basic block
/// using the Alloca.
///
/// If we cannot promote this alloca (because it is read before it is written),
/// return true.  This is necessary in cases where, due to control flow, the
/// alloca is potentially undefined on some control flow paths.  e.g. code like
/// this is potentially correct:
///
///   for (...) { if (c) { A = undef; undef = B; } }
///
/// ... so long as A is not used before undef is set.
static void promoteSingleBlockAlloca(AllocaInst *AI, const AllocaInfo &Info,
                                     LargeBlockInfo &LBI,
                                     AliasSetTracker *AST) {
  // The trickiest case to handle is when we have large blocks. Because of this,
  // this code is optimized assuming that large blocks happen.  This does not
  // significantly pessimize the small block case.  This uses LargeBlockInfo to
  // make it efficient to get the index of various operations in the block.

  // Walk the use-def list of the alloca, getting the locations of all stores.
  typedef SmallVector<std::pair<unsigned, StoreInst *>, 64> StoresByIndexTy;
  StoresByIndexTy StoresByIndex;

  for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end(); UI != E;
       ++UI)
    if (StoreInst *SI = dyn_cast<StoreInst>(*UI))
      StoresByIndex.push_back(std::make_pair(LBI.getInstructionIndex(SI), SI));

  // Sort the stores by their index, making it efficient to do a lookup with a
  // binary search.
  std::sort(StoresByIndex.begin(), StoresByIndex.end(),
            StoreIndexSearchPredicate());

  // Walk all of the loads from this alloca, replacing them with the nearest
  // store above them, if any.
  for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end(); UI != E;) {
    LoadInst *LI = dyn_cast<LoadInst>(*UI++);
    if (!LI)
      continue;

    unsigned LoadIdx = LBI.getInstructionIndex(LI);

    // Find the nearest store that has a lower index than this load.
    StoresByIndexTy::iterator I =
        std::lower_bound(StoresByIndex.begin(), StoresByIndex.end(),
                         std::make_pair(LoadIdx, static_cast<StoreInst *>(0)),
                         StoreIndexSearchPredicate());

    if (I == StoresByIndex.begin())
      // If there is no store before this load, the load takes the undef value.
      LI->replaceAllUsesWith(UndefValue::get(LI->getType()));
    else
      // Otherwise, there was a store before this load, the load takes its value.
      LI->replaceAllUsesWith(llvm::prior(I)->second->getOperand(0));

    if (AST && LI->getType()->isPointerTy())
      AST->deleteValue(LI);
    LI->eraseFromParent();
    LBI.deleteValue(LI);
  }

  // Remove the (now dead) stores and alloca.
  while (!AI->use_empty()) {
    StoreInst *SI = cast<StoreInst>(AI->use_back());
    // Record debuginfo for the store before removing it.
    if (DbgDeclareInst *DDI = Info.DbgDeclare) {
      DIBuilder DIB(*AI->getParent()->getParent()->getParent());
      ConvertDebugDeclareToDebugValue(DDI, SI, DIB);
    }
    SI->eraseFromParent();
    LBI.deleteValue(SI);
  }

  if (AST)
    AST->deleteValue(AI);
  AI->eraseFromParent();
  LBI.deleteValue(AI);

  // The alloca's debuginfo can be removed as well.
  if (DbgDeclareInst *DDI = Info.DbgDeclare)
    DDI->eraseFromParent();

  ++NumLocalPromoted;
}
Esempio n. 22
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void SanitizerCoverageModule::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
                                                    size_t Idx, bool UseCalls) {
  BasicBlock::iterator IP = BB.getFirstInsertionPt();
  bool IsEntryBB = &BB == &F.getEntryBlock();
  DebugLoc EntryLoc;
  if (IsEntryBB) {
    if (auto SP = F.getSubprogram())
      EntryLoc = DebugLoc::get(SP->getScopeLine(), 0, SP);
    // Keep static allocas and llvm.localescape calls in the entry block.  Even
    // if we aren't splitting the block, it's nice for allocas to be before
    // calls.
    IP = PrepareToSplitEntryBlock(BB, IP);
  } else {
    EntryLoc = IP->getDebugLoc();
  }

  IRBuilder<> IRB(&*IP);
  IRB.SetCurrentDebugLocation(EntryLoc);
  if (Options.TracePC) {
    IRB.CreateCall(SanCovTracePC); // gets the PC using GET_CALLER_PC.
    IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
  } else if (Options.TracePCGuard) {
    //auto GuardVar = new GlobalVariable(
    //   *F.getParent(), Int64Ty, false, GlobalVariable::LinkOnceODRLinkage,
    //    Constant::getNullValue(Int64Ty), "__sancov_guard." + F.getName());
    // if (auto Comdat = F.getComdat())
    //  GuardVar->setComdat(Comdat);
    // TODO: add debug into to GuardVar.
    // GuardVar->setSection(SanCovTracePCGuardSection);
    // auto GuardPtr = IRB.CreatePointerCast(GuardVar, IntptrPtrTy);
    auto GuardPtr = IRB.CreateIntToPtr(
        IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
                      ConstantInt::get(IntptrTy, Idx * 4)),
        Int32PtrTy);
    if (!UseCalls) {
      auto GuardLoad = IRB.CreateLoad(GuardPtr);
      GuardLoad->setAtomic(AtomicOrdering::Monotonic);
      GuardLoad->setAlignment(8);
      SetNoSanitizeMetadata(GuardLoad);  // Don't instrument with e.g. asan.
      auto Cmp = IRB.CreateICmpNE(
          GuardLoad, Constant::getNullValue(GuardLoad->getType()));
      auto Ins = SplitBlockAndInsertIfThen(
          Cmp, &*IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
      IRB.SetCurrentDebugLocation(EntryLoc);
      IRB.SetInsertPoint(Ins);
    }
    IRB.CreateCall(SanCovTracePCGuard, GuardPtr);
    IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
  } else {
    Value *GuardP = IRB.CreateAdd(
        IRB.CreatePointerCast(GuardArray, IntptrTy),
        ConstantInt::get(IntptrTy, (1 + NumberOfInstrumentedBlocks()) * 4));
    GuardP = IRB.CreateIntToPtr(GuardP, Int32PtrTy);
    if (Options.TraceBB) {
      IRB.CreateCall(IsEntryBB ? SanCovTraceEnter : SanCovTraceBB, GuardP);
    } else if (UseCalls) {
      IRB.CreateCall(SanCovWithCheckFunction, GuardP);
    } else {
      LoadInst *Load = IRB.CreateLoad(GuardP);
      Load->setAtomic(AtomicOrdering::Monotonic);
      Load->setAlignment(4);
      SetNoSanitizeMetadata(Load);
      Value *Cmp =
          IRB.CreateICmpSGE(Constant::getNullValue(Load->getType()), Load);
      Instruction *Ins = SplitBlockAndInsertIfThen(
          Cmp, &*IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
      IRB.SetInsertPoint(Ins);
      IRB.SetCurrentDebugLocation(EntryLoc);
      // __sanitizer_cov gets the PC of the instruction using GET_CALLER_PC.
      IRB.CreateCall(SanCovFunction, GuardP);
      IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
    }
  }

  if (Options.Use8bitCounters) {
    IRB.SetInsertPoint(&*IP);
    Value *P = IRB.CreateAdd(
        IRB.CreatePointerCast(EightBitCounterArray, IntptrTy),
        ConstantInt::get(IntptrTy, NumberOfInstrumentedBlocks() - 1));
    P = IRB.CreateIntToPtr(P, IRB.getInt8PtrTy());
    LoadInst *LI = IRB.CreateLoad(P);
    Value *Inc = IRB.CreateAdd(LI, ConstantInt::get(IRB.getInt8Ty(), 1));
    StoreInst *SI = IRB.CreateStore(Inc, P);
    SetNoSanitizeMetadata(LI);
    SetNoSanitizeMetadata(SI);
  }
}
Esempio n. 23
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/// Many allocas are only used within a single basic block.  If this is the
/// case, avoid traversing the CFG and inserting a lot of potentially useless
/// PHI nodes by just performing a single linear pass over the basic block
/// using the Alloca.
///
/// If we cannot promote this alloca (because it is read before it is written),
/// return false.  This is necessary in cases where, due to control flow, the
/// alloca is undefined only on some control flow paths.  e.g. code like
/// this is correct in LLVM IR:
///  // A is an alloca with no stores so far
///  for (...) {
///    int t = *A;
///    if (!first_iteration)
///      use(t);
///    *A = 42;
///  }
static bool promoteSingleBlockAlloca(AllocaInst *AI, const AllocaInfo &Info,
                                     LargeBlockInfo &LBI,
                                     const DataLayout &DL,
                                     DominatorTree &DT,
                                     AssumptionCache *AC) {
  // The trickiest case to handle is when we have large blocks. Because of this,
  // this code is optimized assuming that large blocks happen.  This does not
  // significantly pessimize the small block case.  This uses LargeBlockInfo to
  // make it efficient to get the index of various operations in the block.

  // Walk the use-def list of the alloca, getting the locations of all stores.
  using StoresByIndexTy = SmallVector<std::pair<unsigned, StoreInst *>, 64>;
  StoresByIndexTy StoresByIndex;

  for (User *U : AI->users())
    if (StoreInst *SI = dyn_cast<StoreInst>(U))
      StoresByIndex.push_back(std::make_pair(LBI.getInstructionIndex(SI), SI));

  // Sort the stores by their index, making it efficient to do a lookup with a
  // binary search.
  llvm::sort(StoresByIndex, less_first());

  // Walk all of the loads from this alloca, replacing them with the nearest
  // store above them, if any.
  for (auto UI = AI->user_begin(), E = AI->user_end(); UI != E;) {
    LoadInst *LI = dyn_cast<LoadInst>(*UI++);
    if (!LI)
      continue;

    unsigned LoadIdx = LBI.getInstructionIndex(LI);

    // Find the nearest store that has a lower index than this load.
    StoresByIndexTy::iterator I =
        std::lower_bound(StoresByIndex.begin(), StoresByIndex.end(),
                         std::make_pair(LoadIdx,
                                        static_cast<StoreInst *>(nullptr)),
                         less_first());
    if (I == StoresByIndex.begin()) {
      if (StoresByIndex.empty())
        // If there are no stores, the load takes the undef value.
        LI->replaceAllUsesWith(UndefValue::get(LI->getType()));
      else
        // There is no store before this load, bail out (load may be affected
        // by the following stores - see main comment).
        return false;
    } else {
      // Otherwise, there was a store before this load, the load takes its value.
      // Note, if the load was marked as nonnull we don't want to lose that
      // information when we erase it. So we preserve it with an assume.
      Value *ReplVal = std::prev(I)->second->getOperand(0);
      if (AC && LI->getMetadata(LLVMContext::MD_nonnull) &&
          !isKnownNonZero(ReplVal, DL, 0, AC, LI, &DT))
        addAssumeNonNull(AC, LI);

      // If the replacement value is the load, this must occur in unreachable
      // code.
      if (ReplVal == LI)
        ReplVal = UndefValue::get(LI->getType());

      LI->replaceAllUsesWith(ReplVal);
    }

    LI->eraseFromParent();
    LBI.deleteValue(LI);
  }

  // Remove the (now dead) stores and alloca.
  while (!AI->use_empty()) {
    StoreInst *SI = cast<StoreInst>(AI->user_back());
    // Record debuginfo for the store before removing it.
    for (DbgVariableIntrinsic *DII : Info.DbgDeclares) {
      DIBuilder DIB(*AI->getModule(), /*AllowUnresolved*/ false);
      ConvertDebugDeclareToDebugValue(DII, SI, DIB);
    }
    SI->eraseFromParent();
    LBI.deleteValue(SI);
  }

  AI->eraseFromParent();
  LBI.deleteValue(AI);

  // The alloca's debuginfo can be removed as well.
  for (DbgVariableIntrinsic *DII : Info.DbgDeclares) {
    DII->eraseFromParent();
    LBI.deleteValue(DII);
  }

  ++NumLocalPromoted;
  return true;
}
Esempio n. 24
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void Lint::visitLoadInst(LoadInst &I) {
  visitMemoryReference(I, I.getPointerOperand(),
                       DL->getTypeStoreSize(I.getType()), I.getAlignment(),
                       I.getType(), MemRef::Read);
}
void SanitizerCoverageModule::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
                                                    bool UseCalls) {
  // Don't insert coverage for unreachable blocks: we will never call
  // __sanitizer_cov() for them, so counting them in
  // NumberOfInstrumentedBlocks() might complicate calculation of code coverage
  // percentage. Also, unreachable instructions frequently have no debug
  // locations.
  if (isa<UnreachableInst>(BB.getTerminator()))
    return;
  BasicBlock::iterator IP = BB.getFirstInsertionPt(), BE = BB.end();
  // Skip static allocas at the top of the entry block so they don't become
  // dynamic when we split the block.  If we used our optimized stack layout,
  // then there will only be one alloca and it will come first.
  for (; IP != BE; ++IP) {
    AllocaInst *AI = dyn_cast<AllocaInst>(IP);
    if (!AI || !AI->isStaticAlloca())
      break;
  }

  bool IsEntryBB = &BB == &F.getEntryBlock();
  DebugLoc EntryLoc;
  if (IsEntryBB) {
    if (auto SP = getDISubprogram(&F))
      EntryLoc = DebugLoc::get(SP->getScopeLine(), 0, SP);
  } else {
    EntryLoc = IP->getDebugLoc();
  }

  IRBuilder<> IRB(IP);
  IRB.SetCurrentDebugLocation(EntryLoc);
  SmallVector<Value *, 1> Indices;
  Value *GuardP = IRB.CreateAdd(
      IRB.CreatePointerCast(GuardArray, IntptrTy),
      ConstantInt::get(IntptrTy, (1 + NumberOfInstrumentedBlocks()) * 4));
  Type *Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
  GuardP = IRB.CreateIntToPtr(GuardP, Int32PtrTy);
  if (UseCalls) {
    IRB.CreateCall(SanCovWithCheckFunction, GuardP);
  } else {
    LoadInst *Load = IRB.CreateLoad(GuardP);
    Load->setAtomic(Monotonic);
    Load->setAlignment(4);
    SetNoSanitizeMetadata(Load);
    Value *Cmp = IRB.CreateICmpSGE(Constant::getNullValue(Load->getType()), Load);
    Instruction *Ins = SplitBlockAndInsertIfThen(
        Cmp, IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
    IRB.SetInsertPoint(Ins);
    IRB.SetCurrentDebugLocation(EntryLoc);
    // __sanitizer_cov gets the PC of the instruction using GET_CALLER_PC.
    IRB.CreateCall(SanCovFunction, GuardP);
    IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
  }

  if (Options.Use8bitCounters) {
    IRB.SetInsertPoint(IP);
    Value *P = IRB.CreateAdd(
        IRB.CreatePointerCast(EightBitCounterArray, IntptrTy),
        ConstantInt::get(IntptrTy, NumberOfInstrumentedBlocks() - 1));
    P = IRB.CreateIntToPtr(P, IRB.getInt8PtrTy());
    LoadInst *LI = IRB.CreateLoad(P);
    Value *Inc = IRB.CreateAdd(LI, ConstantInt::get(IRB.getInt8Ty(), 1));
    StoreInst *SI = IRB.CreateStore(Inc, P);
    SetNoSanitizeMetadata(LI);
    SetNoSanitizeMetadata(SI);
  }

  if (Options.TraceBB) {
    // Experimental support for tracing.
    // Insert a callback with the same guard variable as used for coverage.
    IRB.SetInsertPoint(IP);
    IRB.CreateCall(IsEntryBB ? SanCovTraceEnter : SanCovTraceBB, GuardP);
  }
}
/// PromoteSingleBlockAlloca - Many allocas are only used within a single basic
/// block.  If this is the case, avoid traversing the CFG and inserting a lot of
/// potentially useless PHI nodes by just performing a single linear pass over
/// the basic block using the Alloca.
///
/// If we cannot promote this alloca (because it is read before it is written),
/// return true.  This is necessary in cases where, due to control flow, the
/// alloca is potentially undefined on some control flow paths.  e.g. code like
/// this is potentially correct:
///
///   for (...) { if (c) { A = undef; undef = B; } }
///
/// ... so long as A is not used before undef is set.
///
void PromoteMem2Reg::PromoteSingleBlockAlloca(AllocaInst *AI, AllocaInfo &Info,
                                              LargeBlockInfo &LBI) {
  // The trickiest case to handle is when we have large blocks. Because of this,
  // this code is optimized assuming that large blocks happen.  This does not
  // significantly pessimize the small block case.  This uses LargeBlockInfo to
  // make it efficient to get the index of various operations in the block.
  
  // Clear out UsingBlocks.  We will reconstruct it here if needed.
  Info.UsingBlocks.clear();
  
  // Walk the use-def list of the alloca, getting the locations of all stores.
  typedef SmallVector<std::pair<unsigned, StoreInst*>, 64> StoresByIndexTy;
  StoresByIndexTy StoresByIndex;
  
  for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
       UI != E; ++UI) 
    if (StoreInst *SI = dyn_cast<StoreInst>(*UI))
      StoresByIndex.push_back(std::make_pair(LBI.getInstructionIndex(SI), SI));

  // If there are no stores to the alloca, just replace any loads with undef.
  if (StoresByIndex.empty()) {
    for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end(); UI != E;) 
      if (LoadInst *LI = dyn_cast<LoadInst>(*UI++)) {
        LI->replaceAllUsesWith(UndefValue::get(LI->getType()));
        if (AST && LI->getType()->isPointerTy())
          AST->deleteValue(LI);
        LBI.deleteValue(LI);
        LI->eraseFromParent();
      }
    return;
  }
  
  // Sort the stores by their index, making it efficient to do a lookup with a
  // binary search.
  std::sort(StoresByIndex.begin(), StoresByIndex.end());
  
  // Walk all of the loads from this alloca, replacing them with the nearest
  // store above them, if any.
  for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end(); UI != E;) {
    LoadInst *LI = dyn_cast<LoadInst>(*UI++);
    if (!LI) continue;
    
    unsigned LoadIdx = LBI.getInstructionIndex(LI);
    
    // Find the nearest store that has a lower than this load. 
    StoresByIndexTy::iterator I = 
      std::lower_bound(StoresByIndex.begin(), StoresByIndex.end(),
                       std::pair<unsigned, StoreInst*>(LoadIdx, static_cast<StoreInst*>(0)),
                       StoreIndexSearchPredicate());
    
    // If there is no store before this load, then we can't promote this load.
    if (I == StoresByIndex.begin()) {
      // Can't handle this load, bail out.
      Info.UsingBlocks.push_back(LI->getParent());
      continue;
    }
      
    // Otherwise, there was a store before this load, the load takes its value.
    --I;
    LI->replaceAllUsesWith(I->second->getOperand(0));
    if (AST && LI->getType()->isPointerTy())
      AST->deleteValue(LI);
    LI->eraseFromParent();
    LBI.deleteValue(LI);
  }
}
Esempio n. 27
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void SanitizerCoverageModule::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
                                                    bool UseCalls) {
  // Don't insert coverage for unreachable blocks: we will never call
  // __sanitizer_cov() for them, so counting them in
  // NumberOfInstrumentedBlocks() might complicate calculation of code coverage
  // percentage. Also, unreachable instructions frequently have no debug
  // locations.
  if (isa<UnreachableInst>(BB.getTerminator()))
    return;
  BasicBlock::iterator IP = BB.getFirstInsertionPt();

  bool IsEntryBB = &BB == &F.getEntryBlock();
  DebugLoc EntryLoc;
  if (IsEntryBB) {
    if (auto SP = getDISubprogram(&F))
      EntryLoc = DebugLoc::get(SP->getScopeLine(), 0, SP);
    // Keep static allocas and llvm.localescape calls in the entry block.  Even
    // if we aren't splitting the block, it's nice for allocas to be before
    // calls.
    IP = PrepareToSplitEntryBlock(BB, IP);
  } else {
    EntryLoc = IP->getDebugLoc();
  }

  IRBuilder<> IRB(&*IP);
  IRB.SetCurrentDebugLocation(EntryLoc);
  Value *GuardP = IRB.CreateAdd(
      IRB.CreatePointerCast(GuardArray, IntptrTy),
      ConstantInt::get(IntptrTy, (1 + NumberOfInstrumentedBlocks()) * 4));
  Type *Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
  GuardP = IRB.CreateIntToPtr(GuardP, Int32PtrTy);
  if (Options.TracePC) {
    IRB.CreateCall(SanCovTracePC);
  } else if (Options.TraceBB) {
    IRB.CreateCall(IsEntryBB ? SanCovTraceEnter : SanCovTraceBB, GuardP);
  } else if (UseCalls) {
    IRB.CreateCall(SanCovWithCheckFunction, GuardP);
  } else {
    LoadInst *Load = IRB.CreateLoad(GuardP);
    Load->setAtomic(Monotonic);
    Load->setAlignment(4);
    SetNoSanitizeMetadata(Load);
    Value *Cmp = IRB.CreateICmpSGE(Constant::getNullValue(Load->getType()), Load);
    Instruction *Ins = SplitBlockAndInsertIfThen(
        Cmp, &*IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
    IRB.SetInsertPoint(Ins);
    IRB.SetCurrentDebugLocation(EntryLoc);
    // __sanitizer_cov gets the PC of the instruction using GET_CALLER_PC.
    IRB.CreateCall(SanCovFunction, GuardP);
    IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
  }

  if (Options.Use8bitCounters) {
    IRB.SetInsertPoint(&*IP);
    Value *P = IRB.CreateAdd(
        IRB.CreatePointerCast(EightBitCounterArray, IntptrTy),
        ConstantInt::get(IntptrTy, NumberOfInstrumentedBlocks() - 1));
    P = IRB.CreateIntToPtr(P, IRB.getInt8PtrTy());
    LoadInst *LI = IRB.CreateLoad(P);
    Value *Inc = IRB.CreateAdd(LI, ConstantInt::get(IRB.getInt8Ty(), 1));
    StoreInst *SI = IRB.CreateStore(Inc, P);
    SetNoSanitizeMetadata(LI);
    SetNoSanitizeMetadata(SI);
  }
}
Esempio n. 28
0
/// \brief Rewrite as many loads as possible given a single store.
///
/// When there is only a single store, we can use the domtree to trivially
/// replace all of the dominated loads with the stored value. Do so, and return
/// true if this has successfully promoted the alloca entirely. If this returns
/// false there were some loads which were not dominated by the single store
/// and thus must be phi-ed with undef. We fall back to the standard alloca
/// promotion algorithm in that case.
static bool rewriteSingleStoreAlloca(AllocaInst *AI, AllocaInfo &Info,
                                     LargeBlockInfo &LBI,
                                     DominatorTree &DT,
                                     AliasSetTracker *AST) {
  StoreInst *OnlyStore = Info.OnlyStore;
  bool StoringGlobalVal = !isa<Instruction>(OnlyStore->getOperand(0));
  BasicBlock *StoreBB = OnlyStore->getParent();
  int StoreIndex = -1;

  // Clear out UsingBlocks.  We will reconstruct it here if needed.
  Info.UsingBlocks.clear();

  for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end(); UI != E;) {
    Instruction *UserInst = cast<Instruction>(*UI++);
    if (!isa<LoadInst>(UserInst)) {
      assert(UserInst == OnlyStore && "Should only have load/stores");
      continue;
    }
    LoadInst *LI = cast<LoadInst>(UserInst);

    // Okay, if we have a load from the alloca, we want to replace it with the
    // only value stored to the alloca.  We can do this if the value is
    // dominated by the store.  If not, we use the rest of the mem2reg machinery
    // to insert the phi nodes as needed.
    if (!StoringGlobalVal) { // Non-instructions are always dominated.
      if (LI->getParent() == StoreBB) {
        // If we have a use that is in the same block as the store, compare the
        // indices of the two instructions to see which one came first.  If the
        // load came before the store, we can't handle it.
        if (StoreIndex == -1)
          StoreIndex = LBI.getInstructionIndex(OnlyStore);

        if (unsigned(StoreIndex) > LBI.getInstructionIndex(LI)) {
          // Can't handle this load, bail out.
          Info.UsingBlocks.push_back(StoreBB);
          continue;
        }

      } else if (LI->getParent() != StoreBB &&
                 !DT.dominates(StoreBB, LI->getParent())) {
        // If the load and store are in different blocks, use BB dominance to
        // check their relationships.  If the store doesn't dom the use, bail
        // out.
        Info.UsingBlocks.push_back(LI->getParent());
        continue;
      }
    }

    // Otherwise, we *can* safely rewrite this load.
    Value *ReplVal = OnlyStore->getOperand(0);
    // If the replacement value is the load, this must occur in unreachable
    // code.
    if (ReplVal == LI)
      ReplVal = UndefValue::get(LI->getType());
    LI->replaceAllUsesWith(ReplVal);
    if (AST && LI->getType()->isPointerTy())
      AST->deleteValue(LI);
    LI->eraseFromParent();
    LBI.deleteValue(LI);
  }

  // Finally, after the scan, check to see if the store is all that is left.
  if (!Info.UsingBlocks.empty())
    return false; // If not, we'll have to fall back for the remainder.

  // Record debuginfo for the store and remove the declaration's
  // debuginfo.
  if (DbgDeclareInst *DDI = Info.DbgDeclare) {
    DIBuilder DIB(*AI->getParent()->getParent()->getParent());
    ConvertDebugDeclareToDebugValue(DDI, Info.OnlyStore, DIB);
    DDI->eraseFromParent();
  }
  // Remove the (now dead) store and alloca.
  Info.OnlyStore->eraseFromParent();
  LBI.deleteValue(Info.OnlyStore);

  if (AST)
    AST->deleteValue(AI);
  AI->eraseFromParent();
  LBI.deleteValue(AI);
  return true;
}
Esempio n. 29
-1
void Closure::unpack_struct(Scope<Value *> &dst,
                            llvm::Type *
#if LLVM_VERSION >= 37
                            type
#endif
                            ,
                            Value *src,
                            IRBuilder<> *builder) {
    // type, type of src should be a pointer to a struct of the type returned by build_type
    int idx = 0;
    LLVMContext &context = builder->getContext();
    vector<string> nm = names();
    for (size_t i = 0; i < nm.size(); i++) {
#if LLVM_VERSION >= 37
        Value *ptr = builder->CreateConstInBoundsGEP2_32(type, src, 0, idx++);
#else
        Value *ptr = builder->CreateConstInBoundsGEP2_32(src, 0, idx++);
#endif
        LoadInst *load = builder->CreateLoad(ptr);
        if (load->getType()->isPointerTy()) {
            // Give it a unique type so that tbaa tells llvm that this can't alias anything
            LLVMMDNodeArgumentType md_args[] = {MDString::get(context, nm[i])};
            load->setMetadata("tbaa", MDNode::get(context, md_args));
        }
        dst.push(nm[i], load);
        load->setName(nm[i]);
    }
}
Esempio n. 30
-1
//
// Method: runOnModule()
//
// Description:
//  Entry point for this LLVM pass. Search for insert/extractvalue instructions
//  that can be simplified.
//
// Inputs:
//  M - A reference to the LLVM module to transform.
//
// Outputs:
//  M - The transformed LLVM module.
//
// Return value:
// true  - The module was modified.
// false - The module was not modified.
//
bool SimplifyLoad::runOnModule(Module& M) {
  // Repeat till no change
  bool changed;
  do {
    changed = false;
    for (Module::iterator F = M.begin(); F != M.end(); ++F) {
      for (Function::iterator B = F->begin(), FE = F->end(); B != FE; ++B) {      
        for (BasicBlock::iterator I = B->begin(), BE = B->end(); I != BE;) {
          LoadInst *LI = dyn_cast<LoadInst>(I++);
          if(!LI)
            continue;
          if(LI->hasOneUse()) {
            if(CastInst *CI = dyn_cast<CastInst>(*(LI->use_begin()))) {
              if(LI->getType()->isPointerTy()) {
                if(ConstantExpr *CE = dyn_cast<ConstantExpr>(LI->getOperand(0))) {
                  if(const PointerType *PTy = dyn_cast<PointerType>(CE->getOperand(0)->getType()))
                    if(PTy->getElementType() == CI->getType()) {
                      LoadInst *LINew = new LoadInst(CE->getOperand(0), "", LI);
                      CI->replaceAllUsesWith(LINew);
                    }
                }
              }
            }
          }


        }
      }
    }
  } while(changed);
  return (numErased > 0);
}