/*

  This file is part of solidity.

  solidity is free software: you can redistribute it and/or modify

  it under the terms of the GNU General Public License as published by

  the Free Software Foundation, either version 3 of the License, or

  (at your option) any later version.

  solidity is distributed in the hope that it will be useful,

  but WITHOUT ANY WARRANTY; without even the implied warranty of

  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License

  along with solidity.  If not, see <http://www.gnu.org/licenses/>.

*/

/**

* Module providing metrics for the optimizer.

*/

#include <libyul/optimiser/Metrics.h>

#include <libyul/optimiser/OptimizerUtilities.h>

#include <libyul/backends/evm/EVMDialect.h>

#include <libyul/AST.h>

#include <libyul/Exceptions.h>

#include <libyul/Utilities.h>

#include <libevmasm/Instruction.h>

#include <libsolutil/CommonData.h>

using namespace solidity;

using namespace solidity::yul;

using namespace solidity::util;

size_t CodeWeights::costOf(Statement const& _statement) const

{

  if (std::holds_alternative<ExpressionStatement>(_statement))

    return expressionStatementCost;

  else if (std::holds_alternative<Assignment>(_statement))

    return assignmentCost;

  else if (std::holds_alternative<VariableDeclaration>(_statement))

    return variableDeclarationCost;

  else if (std::holds_alternative<FunctionDefinition>(_statement))

    return functionDefinitionCost;

  else if (std::holds_alternative<If>(_statement))

    return ifCost;

  else if (std::holds_alternative<Switch>(_statement))

    return switchCost + caseCost * std::get<Switch>(_statement).cases.size();

  else if (std::holds_alternative<ForLoop>(_statement))

    return forLoopCost;

  else if (std::holds_alternative<Break>(_statement))

    return breakCost;

  else if (std::holds_alternative<Continue>(_statement))

    return continueCost;

  else if (std::holds_alternative<Leave>(_statement))

    return leaveCost;

  else if (std::holds_alternative<Block>(_statement))

    return blockCost;

  else

    yulAssert(false, "If you add a new statement type, you must update CodeWeights.");

}

size_t CodeWeights::costOf(Expression const& _expression) const

{

  if (std::holds_alternative<FunctionCall>(_expression))

    return functionCallCost;

  else if (std::holds_alternative<Identifier>(_expression))

    return identifierCost;

  else if (Literal const* literal = std::get_if<Literal>(&_expression))

  {

    // Avoid strings because they could be longer than 32 bytes.

    if (literal->kind != LiteralKind::String && literal->value.value() == 0)

      return literalZeroCost;

    else

      return literalCost;

  }

  else

    yulAssert(false, "If you add a new expression type, you must update CodeWeights.");

}

size_t CodeSize::codeSize(Statement const& _statement, CodeWeights const& _weights)

{

  CodeSize cs(true, _weights);

  cs.visit(_statement);

  return cs.m_size;

}

size_t CodeSize::codeSize(Expression const& _expression, CodeWeights const& _weights)

{

  CodeSize cs(true, _weights);

  cs.visit(_expression);

  return cs.m_size;

}

size_t CodeSize::codeSize(Block const& _block, CodeWeights const& _weights)

{

  CodeSize cs(true, _weights);

  cs(_block);

  return cs.m_size;

}

size_t CodeSize::codeSizeIncludingFunctions(Block const& _block, CodeWeights const& _weights)

{

  CodeSize cs(false, _weights);

  cs(_block);

  return cs.m_size;

}

void CodeSize::visit(Statement const& _statement)

{

  if (std::holds_alternative<FunctionDefinition>(_statement) && m_ignoreFunctions)

    return;

  m_size += m_weights.costOf(_statement);

  ASTWalker::visit(_statement);

}

void CodeSize::visit(Expression const& _expression)

{

  m_size += m_weights.costOf(_expression);

  ASTWalker::visit(_expression);

}

size_t CodeCost::codeCost(Dialect const& _dialect, Expression const& _expr)

{

  CodeCost cc(_dialect);

  cc.visit(_expr);

  return cc.m_cost;

}

void CodeCost::operator()(FunctionCall const& _funCall)

{

  ASTWalker::operator()(_funCall);

  if (auto instruction = toEVMInstruction(m_dialect, _funCall.functionName))

  {

    addInstructionCost(*instruction);

    return;

  }

  m_cost += 49;

}

void CodeCost::operator()(Literal const& _literal)

{

  yulAssert(m_cost >= 1, "Should assign cost one in visit(Expression).");

  size_t cost = 0;

  switch (_literal.kind)

  {

  case LiteralKind::Boolean:

    break;

  case LiteralKind::Number:

    for (u256 n = _literal.value.value(); n >= 0x100; n >>= 8)

      cost++;

    if (_literal.value.value() == 0)

      if (auto evmDialect = dynamic_cast<EVMDialect const*>(&m_dialect))

        if (evmDialect->evmVersion().hasPush0())

          --m_cost;

    break;

  case LiteralKind::String:

    cost = formatLiteral(_literal).size();

    break;

  }

  m_cost += cost;

}

void CodeCost::visit(Statement const& _statement)

{

  ++m_cost;

  ASTWalker::visit(_statement);

}

void CodeCost::visit(Expression const& _expression)

{

  ++m_cost;

  ASTWalker::visit(_expression);

}

void CodeCost::addInstructionCost(evmasm::Instruction _instruction)

{

  evmasm::Tier gasPriceTier = evmasm::instructionInfo(_instruction, evmVersionFromDialect(m_dialect)).gasPriceTier;

  if (gasPriceTier < evmasm::Tier::VeryLow)

    m_cost -= 1;

  else if (gasPriceTier < evmasm::Tier::High)

    m_cost += 1;

  else

    m_cost += 49;

}

void AssignmentCounter::operator()(Assignment const& _assignment)

{

  for (auto const& variable: _assignment.variableNames)

    ++m_assignmentCounters[variable.name];

}

size_t AssignmentCounter::assignmentCount(YulName _name) const

{

  auto it = m_assignmentCounters.find(_name);

  return (it == m_assignmentCounters.end()) ? 0 : it->second;

}