Expression simplifier.

2023-10-03 13:03:40 +00:00 · 2018-02-06 22:51:30 +01:00
parent 591813638e
commit 9eea3f29ba
6 changed files with 453 additions and 0 deletions
@@ -0,0 +1,172 @@
+/*
+	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 <libjulia/optimiser/SimplificationRules.h>
+
+#include <libjulia/optimiser/Utilities.h>
+#include <libjulia/optimiser/ASTCopier.h>
+
+#include <libsolidity/inlineasm/AsmData.h>
+
+#include <libevmasm/RuleList.h>
+
+using namespace std;
+using namespace dev;
+using namespace dev::julia;
+
+
+tuple<Pattern, function<Pattern()>, bool> const* SimplificationRules::findFirstMatch(Expression const& _expr)
+{
+	if (_expr.type() != typeid(FunctionalInstruction))
+		return nullptr;
+
+	static SimplificationRules rules;
+
+	FunctionalInstruction const& instruction = boost::get<FunctionalInstruction const&>(_expr);
+	for (auto const& rule: rules.m_rules[byte(instruction.instruction)])
+	{
+		rules.resetMatchGroups();
+		if (std::get<0>(rule).matches(_expr))
+			return &rule;
+	}
+	return nullptr;
+}
+
+void SimplificationRules::addRules(vector<tuple<Pattern, function<Pattern()>, bool>> const& _rules)
+{
+	for (auto const& r: _rules)
+		addRule(r);
+}
+
+void SimplificationRules::addRule(tuple<Pattern, function<Pattern()>, bool> const& _rule)
+{
+	m_rules[byte(std::get<0>(_rule).instruction())].push_back(_rule);
+}
+
+SimplificationRules::SimplificationRules()
+{
+	// Multiple occurences 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));
+}
+
+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) const
+{
+	if (m_kind == PatternKind::Constant)
+	{
+		if (_expr.type() != typeid(Literal))
+			return false;
+		Literal const& literal = boost::get<Literal const&>(_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 const&>(_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)))
+				return false;
+	}
+	else
+	{
+		assertThrow(m_arguments.empty(), OptimizerException, "");
+	}
+	// We do not support matching multiple expressions that require the same value.
+	if (m_matchGroup)
+	{
+		if (m_matchGroups->count(m_matchGroup))
+			return false;
+		(*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, m_data->str(), ""};
+	}
+	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 const&>(matchGroupValue());
+	assertThrow(literal.kind == assembly::LiteralKind::Number, 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];
+}