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			226 lines
		
	
	
		
			6.9 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			226 lines
		
	
	
		
			6.9 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
/*
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	This file is part of solidity.
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	solidity is free software: you can redistribute it and/or modify
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	it under the terms of the GNU General Public License as published by
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	the Free Software Foundation, either version 3 of the License, or
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	(at your option) any later version.
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	solidity is distributed in the hope that it will be useful,
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	but WITHOUT ANY WARRANTY; without even the implied warranty of
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	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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	GNU General Public License for more details.
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	You should have received a copy of the GNU General Public License
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	along with solidity.  If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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 * Module for applying replacement rules against Expressions.
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 */
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#include <libyul/optimiser/SimplificationRules.h>
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#include <libyul/optimiser/ASTCopier.h>
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#include <libyul/optimiser/Semantics.h>
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#include <libyul/optimiser/SyntacticalEquality.h>
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#include <libyul/AsmData.h>
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#include <libyul/Utilities.h>
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#include <libevmasm/RuleList.h>
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using namespace std;
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using namespace dev;
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using namespace langutil;
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using namespace yul;
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SimplificationRule<Pattern> const* SimplificationRules::findFirstMatch(
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	Expression const& _expr,
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	Dialect const& _dialect,
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	map<YulString, Expression const*> const& _ssaValues
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)
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{
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	if (_expr.type() != typeid(FunctionalInstruction))
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		return nullptr;
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	static SimplificationRules rules;
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	assertThrow(rules.isInitialized(), OptimizerException, "Rule list not properly initialized.");
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	FunctionalInstruction const& instruction = boost::get<FunctionalInstruction>(_expr);
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	for (auto const& rule: rules.m_rules[uint8_t(instruction.instruction)])
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	{
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		rules.resetMatchGroups();
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		if (rule.pattern.matches(_expr, _dialect, _ssaValues))
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			return &rule;
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	}
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	return nullptr;
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}
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bool SimplificationRules::isInitialized() const
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{
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	return !m_rules[uint8_t(solidity::Instruction::ADD)].empty();
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}
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void SimplificationRules::addRules(vector<SimplificationRule<Pattern>> const& _rules)
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{
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	for (auto const& r: _rules)
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		addRule(r);
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}
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void SimplificationRules::addRule(SimplificationRule<Pattern> const& _rule)
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{
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	m_rules[uint8_t(_rule.pattern.instruction())].push_back(_rule);
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}
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SimplificationRules::SimplificationRules()
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{
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	// Multiple occurrences of one of these inside one rule must match the same equivalence class.
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	// Constants.
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	Pattern A(PatternKind::Constant);
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	Pattern B(PatternKind::Constant);
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	Pattern C(PatternKind::Constant);
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	// Anything.
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	Pattern X;
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	Pattern Y;
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	A.setMatchGroup(1, m_matchGroups);
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	B.setMatchGroup(2, m_matchGroups);
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	C.setMatchGroup(3, m_matchGroups);
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	X.setMatchGroup(4, m_matchGroups);
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	Y.setMatchGroup(5, m_matchGroups);
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	addRules(simplificationRuleList(A, B, C, X, Y));
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	assertThrow(isInitialized(), OptimizerException, "Rule list not properly initialized.");
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}
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Pattern::Pattern(solidity::Instruction _instruction, vector<Pattern> const& _arguments):
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	m_kind(PatternKind::Operation),
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	m_instruction(_instruction),
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	m_arguments(_arguments)
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{
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}
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void Pattern::setMatchGroup(unsigned _group, map<unsigned, Expression const*>& _matchGroups)
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{
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	m_matchGroup = _group;
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	m_matchGroups = &_matchGroups;
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}
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bool Pattern::matches(
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	Expression const& _expr,
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	Dialect const& _dialect,
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	map<YulString, Expression const*> const& _ssaValues
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) const
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{
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	Expression const* expr = &_expr;
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	// Resolve the variable if possible.
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	// Do not do it for "Any" because we can check identity better for variables.
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	if (m_kind != PatternKind::Any && _expr.type() == typeid(Identifier))
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	{
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		YulString varName = boost::get<Identifier>(_expr).name;
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		if (_ssaValues.count(varName))
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			if (Expression const* new_expr = _ssaValues.at(varName))
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				expr = new_expr;
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	}
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	assertThrow(expr, OptimizerException, "");
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	if (m_kind == PatternKind::Constant)
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	{
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		if (expr->type() != typeid(Literal))
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			return false;
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		Literal const& literal = boost::get<Literal>(*expr);
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		if (literal.kind != LiteralKind::Number)
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			return false;
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		if (m_data && *m_data != u256(literal.value.str()))
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			return false;
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		assertThrow(m_arguments.empty(), OptimizerException, "");
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	}
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	else if (m_kind == PatternKind::Operation)
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	{
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		if (expr->type() != typeid(FunctionalInstruction))
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			return false;
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		FunctionalInstruction const& instr = boost::get<FunctionalInstruction>(*expr);
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		if (m_instruction != instr.instruction)
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			return false;
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		assertThrow(m_arguments.size() == instr.arguments.size(), OptimizerException, "");
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		for (size_t i = 0; i < m_arguments.size(); ++i)
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			if (!m_arguments[i].matches(instr.arguments.at(i), _dialect, _ssaValues))
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				return false;
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	}
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	else
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	{
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		assertThrow(m_arguments.empty(), OptimizerException, "\"Any\" should not have arguments.");
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	}
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	if (m_matchGroup)
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	{
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		// We support matching multiple expressions that require the same value
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		// based on identical ASTs, which have to be movable.
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		// TODO: add tests:
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		// - { let x := mload(0) let y := and(x, x) }
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		// - { let x := 4 let y := and(x, y) }
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		// This code uses `_expr` again for "Any", because we want the comparison to be done
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		// on the variables and not their values.
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		// The assumption is that CSE or local value numbering has been done prior to this step.
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		if (m_matchGroups->count(m_matchGroup))
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		{
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			assertThrow(m_kind == PatternKind::Any, OptimizerException, "Match group repetition for non-any.");
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			Expression const* firstMatch = (*m_matchGroups)[m_matchGroup];
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			assertThrow(firstMatch, OptimizerException, "Match set but to null.");
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			return
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				SyntacticallyEqual{}(*firstMatch, _expr) &&
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				MovableChecker(_dialect, _expr).movable();
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		}
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		else if (m_kind == PatternKind::Any)
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			(*m_matchGroups)[m_matchGroup] = &_expr;
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		else
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		{
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			assertThrow(m_kind == PatternKind::Constant, OptimizerException, "Match group set for operation.");
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			// We do not use _expr here, because we want the actual number.
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			(*m_matchGroups)[m_matchGroup] = expr;
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		}
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	}
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	return true;
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}
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solidity::Instruction Pattern::instruction() const
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{
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	assertThrow(m_kind == PatternKind::Operation, OptimizerException, "");
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	return m_instruction;
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}
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Expression Pattern::toExpression(SourceLocation const& _location) const
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{
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	if (matchGroup())
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		return ASTCopier().translate(matchGroupValue());
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	if (m_kind == PatternKind::Constant)
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	{
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		assertThrow(m_data, OptimizerException, "No match group and no constant value given.");
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		return Literal{_location, LiteralKind::Number, YulString{formatNumber(*m_data)}, {}};
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	}
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	else if (m_kind == PatternKind::Operation)
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	{
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		vector<Expression> arguments;
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		for (auto const& arg: m_arguments)
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			arguments.emplace_back(arg.toExpression(_location));
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		return FunctionalInstruction{_location, m_instruction, std::move(arguments)};
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	}
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	assertThrow(false, OptimizerException, "Pattern of kind 'any', but no match group.");
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}
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u256 Pattern::d() const
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{
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	return valueOfNumberLiteral(boost::get<Literal>(matchGroupValue()));
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}
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Expression const& Pattern::matchGroupValue() const
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{
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	assertThrow(m_matchGroup > 0, OptimizerException, "");
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	assertThrow(!!m_matchGroups, OptimizerException, "");
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	assertThrow((*m_matchGroups)[m_matchGroup], OptimizerException, "");
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	return *(*m_matchGroups)[m_matchGroup];
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}
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