Merge pull request #5416 from ethereum/develop

Merge develop into release for 0.5.0

1 files changed, 222 insertions, 0 deletions

diff --git a/libyul/optimiser/SimplificationRules.cpp b/libyul/optimiser/SimplificationRules.cpp
new file mode 100644
index 00000000..5721042f
--- /dev/null
+++ b/libyul/optimiser/SimplificationRules.cpp
@@ -0,0 +1,222 @@
+/*
+	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<YulString, 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[uint8_t(instruction.instruction)])
+	{
+		rules.resetMatchGroups();
+		if (rule.pattern.matches(_expr, _ssaValues))
+			return &rule;
+	}
+	return nullptr;
+}
+
+bool SimplificationRules::isInitialized() const
+{
+	return !m_rules[uint8_t(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[uint8_t(_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<YulString, 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))
+	{
+		YulString 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.str()))
+			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, YulString{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.str()) || isValidHex(literal.value.str()), OptimizerException, "");
+	return u256(literal.value.str());
+}
+
+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];
+}