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/*
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 for applying replacement rules against Expressions.
*/
#include <libyul/optimiser/SimplificationRules.h>
#include <libyul/optimiser/Utilities.h>
#include <libyul/optimiser/ASTCopier.h>
#include <libyul/optimiser/Semantics.h>
#include <libyul/optimiser/SyntacticalEquality.h>
#include <libsolidity/inlineasm/AsmData.h>
#include <libevmasm/RuleList.h>
using namespace std;
using namespace dev;
using namespace dev::yul;
SimplificationRule<Pattern> const* SimplificationRules::findFirstMatch(
Expression const& _expr,
map<string, Expression const*> const& _ssaValues
)
{
if (_expr.type() != typeid(FunctionalInstruction))
return nullptr;
static SimplificationRules rules;
assertThrow(rules.isInitialized(), OptimizerException, "Rule list not properly initialized.");
FunctionalInstruction const& instruction = boost::get<FunctionalInstruction>(_expr);
for (auto const& rule: rules.m_rules[byte(instruction.instruction)])
{
rules.resetMatchGroups();
if (rule.pattern.matches(_expr, _ssaValues))
return &rule;
}
return nullptr;
}
bool SimplificationRules::isInitialized() const
{
return !m_rules[byte(solidity::Instruction::ADD)].empty();
}
void SimplificationRules::addRules(vector<SimplificationRule<Pattern>> const& _rules)
{
for (auto const& r: _rules)
addRule(r);
}
void SimplificationRules::addRule(SimplificationRule<Pattern> const& _rule)
{
m_rules[byte(_rule.pattern.instruction())].push_back(_rule);
}
SimplificationRules::SimplificationRules()
{
// Multiple occurrences of one of these inside one rule must match the same equivalence class.
// Constants.
Pattern A(PatternKind::Constant);
Pattern B(PatternKind::Constant);
Pattern C(PatternKind::Constant);
// Anything.
Pattern X;
Pattern Y;
A.setMatchGroup(1, m_matchGroups);
B.setMatchGroup(2, m_matchGroups);
C.setMatchGroup(3, m_matchGroups);
X.setMatchGroup(4, m_matchGroups);
Y.setMatchGroup(5, m_matchGroups);
addRules(simplificationRuleList(A, B, C, X, Y));
assertThrow(isInitialized(), OptimizerException, "Rule list not properly initialized.");
}
Pattern::Pattern(solidity::Instruction _instruction, vector<Pattern> const& _arguments):
m_kind(PatternKind::Operation),
m_instruction(_instruction),
m_arguments(_arguments)
{
}
void Pattern::setMatchGroup(unsigned _group, map<unsigned, Expression const*>& _matchGroups)
{
m_matchGroup = _group;
m_matchGroups = &_matchGroups;
}
bool Pattern::matches(Expression const& _expr, map<string, Expression const*> const& _ssaValues) const
{
Expression const* expr = &_expr;
// Resolve the variable if possible.
// Do not do it for "Any" because we can check identity better for variables.
if (m_kind != PatternKind::Any && _expr.type() == typeid(Identifier))
{
string const& varName = boost::get<Identifier>(_expr).name;
if (_ssaValues.count(varName))
expr = _ssaValues.at(varName);
}
assertThrow(expr, OptimizerException, "");
if (m_kind == PatternKind::Constant)
{
if (expr->type() != typeid(Literal))
return false;
Literal const& literal = boost::get<Literal>(*expr);
if (literal.kind != assembly::LiteralKind::Number)
return false;
if (m_data && *m_data != u256(literal.value))
return false;
assertThrow(m_arguments.empty(), OptimizerException, "");
}
else if (m_kind == PatternKind::Operation)
{
if (expr->type() != typeid(FunctionalInstruction))
return false;
FunctionalInstruction const& instr = boost::get<FunctionalInstruction>(*expr);
if (m_instruction != instr.instruction)
return false;
assertThrow(m_arguments.size() == instr.arguments.size(), OptimizerException, "");
for (size_t i = 0; i < m_arguments.size(); ++i)
if (!m_arguments[i].matches(instr.arguments.at(i), _ssaValues))
return false;
}
else
{
assertThrow(m_arguments.empty(), OptimizerException, "\"Any\" should not have arguments.");
}
if (m_matchGroup)
{
// We support matching multiple expressions that require the same value
// based on identical ASTs, which have to be movable.
// TODO: add tests:
// - { let x := mload(0) let y := and(x, x) }
// - { let x := 4 let y := and(x, y) }
// This code uses `_expr` again for "Any", because we want the comparison to be done
// on the variables and not their values.
// The assumption is that CSE or local value numbering has been done prior to this step.
if (m_matchGroups->count(m_matchGroup))
{
assertThrow(m_kind == PatternKind::Any, OptimizerException, "Match group repetition for non-any.");
Expression const* firstMatch = (*m_matchGroups)[m_matchGroup];
assertThrow(firstMatch, OptimizerException, "Match set but to null.");
return
SyntacticalEqualityChecker::equal(*firstMatch, _expr) &&
MovableChecker(_expr).movable();
}
else if (m_kind == PatternKind::Any)
(*m_matchGroups)[m_matchGroup] = &_expr;
else
{
assertThrow(m_kind == PatternKind::Constant, OptimizerException, "Match group set for operation.");
// We do not use _expr here, because we want the actual number.
(*m_matchGroups)[m_matchGroup] = expr;
}
}
return true;
}
solidity::Instruction Pattern::instruction() const
{
assertThrow(m_kind == PatternKind::Operation, OptimizerException, "");
return m_instruction;
}
Expression Pattern::toExpression(SourceLocation const& _location) const
{
if (matchGroup())
return ASTCopier().translate(matchGroupValue());
if (m_kind == PatternKind::Constant)
{
assertThrow(m_data, OptimizerException, "No match group and no constant value given.");
return Literal{_location, assembly::LiteralKind::Number, formatNumber(*m_data), ""};
}
else if (m_kind == PatternKind::Operation)
{
vector<Expression> arguments;
for (auto const& arg: m_arguments)
arguments.emplace_back(arg.toExpression(_location));
return FunctionalInstruction{_location, m_instruction, std::move(arguments)};
}
assertThrow(false, OptimizerException, "Pattern of kind 'any', but no match group.");
}
u256 Pattern::d() const
{
Literal const& literal = boost::get<Literal>(matchGroupValue());
assertThrow(literal.kind == assembly::LiteralKind::Number, OptimizerException, "");
assertThrow(isValidDecimal(literal.value) || isValidHex(literal.value), OptimizerException, "");
return u256(literal.value);
}
Expression const& Pattern::matchGroupValue() const
{
assertThrow(m_matchGroup > 0, OptimizerException, "");
assertThrow(!!m_matchGroups, OptimizerException, "");
assertThrow((*m_matchGroups)[m_matchGroup], OptimizerException, "");
return *(*m_matchGroups)[m_matchGroup];
}
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