C++ LoadInst::getType方法代码示例

/// 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);
  }
}

/// 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 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());
}

//
// 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);
}

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;
}

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);
}

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]);
    }
}

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);
}

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);
    }
}

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;
}

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");
}

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
}