//===-- ValueLatticeUtils.cpp - Utils for solving lattices ------*- C++ -*-===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

//

// This file implements common functions useful for performing data-flow

// analyses that propagate values across function boundaries.

//

//===----------------------------------------------------------------------===//

#include "llvm/Analysis/ValueLatticeUtils.h"

#include "llvm/IR/GlobalVariable.h"

#include "llvm/IR/Instructions.h"

using namespace llvm;

bool llvm::canTrackArgumentsInterprocedurally(Function *F) {

  return F->hasLocalLinkage() && !F->hasAddressTaken();

}

bool llvm::canTrackReturnsInterprocedurally(Function *F) {

  return F->hasExactDefinition() && !F->hasFnAttribute(Attribute::Naked);

}

bool llvm::canTrackGlobalVariableInterprocedurally(GlobalVariable *GV) {

  if (GV->isConstant() || !GV->hasLocalLinkage() ||

      !GV->hasDefinitiveInitializer())

    return false;

  return all_of(GV->users(), [&](User *U) {

    // Currently all users of a global variable have to be non-volatile loads

    // or stores of the global type, and the global cannot be stored itself.

    if (auto *Store = dyn_cast<StoreInst>(U))

      return Store->getValueOperand() != GV && !Store->isVolatile() &&

             Store->getValueOperand()->getType() == GV->getValueType();

    if (auto *Load = dyn_cast<LoadInst>(U))

      return !Load->isVolatile() && Load->getType() == GV->getValueType();

    return false;

  });

}