move libevmasm

1 files changed, 511 insertions, 0 deletions

diff --git a/libevmasm/ExpressionClasses.cpp b/libevmasm/ExpressionClasses.cpp
new file mode 100644
index 00000000..9d13a57a
--- /dev/null
+++ b/libevmasm/ExpressionClasses.cpp
@@ -0,0 +1,511 @@
+/*
+	This file is part of cpp-ethereum.
+
+	cpp-ethereum 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.
+
+	cpp-ethereum 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 cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
+*/
+/**
+ * @file ExpressionClasses.cpp
+ * @author Christian <c@ethdev.com>
+ * @date 2015
+ * Container for equivalence classes of expressions for use in common subexpression elimination.
+ */
+
+#include <libevmasm/ExpressionClasses.h>
+#include <utility>
+#include <tuple>
+#include <functional>
+#include <boost/range/adaptor/reversed.hpp>
+#include <boost/noncopyable.hpp>
+#include <libevmasm/Assembly.h>
+#include <libevmasm/CommonSubexpressionEliminator.h>
+
+using namespace std;
+using namespace dev;
+using namespace dev::eth;
+
+
+bool ExpressionClasses::Expression::operator<(ExpressionClasses::Expression const& _other) const
+{
+	assertThrow(!!item && !!_other.item, OptimizerException, "");
+	auto type = item->type();
+	auto otherType = _other.item->type();
+	return std::tie(type, item->data(), arguments, sequenceNumber) <
+		std::tie(otherType, _other.item->data(), _other.arguments, _other.sequenceNumber);
+}
+
+ExpressionClasses::Id ExpressionClasses::find(
+	AssemblyItem const& _item,
+	Ids const& _arguments,
+	bool _copyItem,
+	unsigned _sequenceNumber
+)
+{
+	Expression exp;
+	exp.id = Id(-1);
+	exp.item = &_item;
+	exp.arguments = _arguments;
+	exp.sequenceNumber = _sequenceNumber;
+
+	if (SemanticInformation::isCommutativeOperation(_item))
+		sort(exp.arguments.begin(), exp.arguments.end());
+
+	if (SemanticInformation::isDeterministic(_item))
+	{
+		auto it = m_expressions.find(exp);
+		if (it != m_expressions.end())
+			return it->id;
+	}
+
+	if (_copyItem)
+		exp.item = storeItem(_item);
+
+	ExpressionClasses::Id id = tryToSimplify(exp);
+	if (id < m_representatives.size())
+		exp.id = id;
+	else
+	{
+		exp.id = m_representatives.size();
+		m_representatives.push_back(exp);
+	}
+	m_expressions.insert(exp);
+	return exp.id;
+}
+
+void ExpressionClasses::forceEqual(
+	ExpressionClasses::Id _id,
+	AssemblyItem const& _item,
+	ExpressionClasses::Ids const& _arguments,
+	bool _copyItem
+)
+{
+	Expression exp;
+	exp.id = _id;
+	exp.item = &_item;
+	exp.arguments = _arguments;
+
+	if (SemanticInformation::isCommutativeOperation(_item))
+		sort(exp.arguments.begin(), exp.arguments.end());
+
+	if (_copyItem)
+		exp.item = storeItem(_item);
+
+	m_expressions.insert(exp);
+}
+
+ExpressionClasses::Id ExpressionClasses::newClass(SourceLocation const& _location)
+{
+	Expression exp;
+	exp.id = m_representatives.size();
+	exp.item = storeItem(AssemblyItem(UndefinedItem, (u256(1) << 255) + exp.id, _location));
+	m_representatives.push_back(exp);
+	m_expressions.insert(exp);
+	return exp.id;
+}
+
+bool ExpressionClasses::knownToBeDifferent(ExpressionClasses::Id _a, ExpressionClasses::Id _b)
+{
+	// Try to simplify "_a - _b" and return true iff the value is a non-zero constant.
+	return knownNonZero(find(Instruction::SUB, {_a, _b}));
+}
+
+bool ExpressionClasses::knownToBeDifferentBy32(ExpressionClasses::Id _a, ExpressionClasses::Id _b)
+{
+	// Try to simplify "_a - _b" and return true iff the value is at least 32 away from zero.
+	u256 const* v = knownConstant(find(Instruction::SUB, {_a, _b}));
+	// forbidden interval is ["-31", 31]
+	return v && *v + 31 > u256(62);
+}
+
+bool ExpressionClasses::knownZero(Id _c)
+{
+	return Pattern(u256(0)).matches(representative(_c), *this);
+}
+
+bool ExpressionClasses::knownNonZero(Id _c)
+{
+	return Pattern(u256(0)).matches(representative(find(Instruction::ISZERO, {_c})), *this);
+}
+
+u256 const* ExpressionClasses::knownConstant(Id _c)
+{
+	map<unsigned, Expression const*> matchGroups;
+	Pattern constant(Push);
+	constant.setMatchGroup(1, matchGroups);
+	if (!constant.matches(representative(_c), *this))
+		return nullptr;
+	return &constant.d();
+}
+
+AssemblyItem const* ExpressionClasses::storeItem(AssemblyItem const& _item)
+{
+	m_spareAssemblyItems.push_back(make_shared<AssemblyItem>(_item));
+	return m_spareAssemblyItems.back().get();
+}
+
+string ExpressionClasses::fullDAGToString(ExpressionClasses::Id _id) const
+{
+	Expression const& expr = representative(_id);
+	stringstream str;
+	str << dec << expr.id << ":";
+	if (expr.item)
+	{
+		str << *expr.item << "(";
+		for (Id arg: expr.arguments)
+			str << fullDAGToString(arg) << ",";
+		str << ")";
+	}
+	else
+		str << " UNIQUE";
+	return str.str();
+}
+
+class Rules: public boost::noncopyable
+{
+public:
+	Rules();
+	void resetMatchGroups() { m_matchGroups.clear(); }
+	vector<pair<Pattern, function<Pattern()>>> rules() const { return m_rules; }
+
+private:
+	using Expression = ExpressionClasses::Expression;
+	map<unsigned, Expression const*> m_matchGroups;
+	vector<pair<Pattern, function<Pattern()>>> m_rules;
+};
+
+template <class S> S divWorkaround(S const& _a, S const& _b)
+{
+	return (S)(bigint(_a) / bigint(_b));
+}
+
+template <class S> S modWorkaround(S const& _a, S const& _b)
+{
+	return (S)(bigint(_a) % bigint(_b));
+}
+
+Rules::Rules()
+{
+	// Multiple occurences of one of these inside one rule must match the same equivalence class.
+	// Constants.
+	Pattern A(Push);
+	Pattern B(Push);
+	Pattern C(Push);
+	// Anything.
+	Pattern X;
+	Pattern Y;
+	Pattern Z;
+	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);
+	Z.setMatchGroup(6, m_matchGroups);
+
+	m_rules = vector<pair<Pattern, function<Pattern()>>>{
+		// arithmetics on constants
+		{{Instruction::ADD, {A, B}}, [=]{ return A.d() + B.d(); }},
+		{{Instruction::MUL, {A, B}}, [=]{ return A.d() * B.d(); }},
+		{{Instruction::SUB, {A, B}}, [=]{ return A.d() - B.d(); }},
+		{{Instruction::DIV, {A, B}}, [=]{ return B.d() == 0 ? 0 : divWorkaround(A.d(), B.d()); }},
+		{{Instruction::SDIV, {A, B}}, [=]{ return B.d() == 0 ? 0 : s2u(divWorkaround(u2s(A.d()), u2s(B.d()))); }},
+		{{Instruction::MOD, {A, B}}, [=]{ return B.d() == 0 ? 0 : modWorkaround(A.d(), B.d()); }},
+		{{Instruction::SMOD, {A, B}}, [=]{ return B.d() == 0 ? 0 : s2u(modWorkaround(u2s(A.d()), u2s(B.d()))); }},
+		{{Instruction::EXP, {A, B}}, [=]{ return u256(boost::multiprecision::powm(bigint(A.d()), bigint(B.d()), bigint(1) << 256)); }},
+		{{Instruction::NOT, {A}}, [=]{ return ~A.d(); }},
+		{{Instruction::LT, {A, B}}, [=]() { return A.d() < B.d() ? u256(1) : 0; }},
+		{{Instruction::GT, {A, B}}, [=]() -> u256 { return A.d() > B.d() ? 1 : 0; }},
+		{{Instruction::SLT, {A, B}}, [=]() -> u256 { return u2s(A.d()) < u2s(B.d()) ? 1 : 0; }},
+		{{Instruction::SGT, {A, B}}, [=]() -> u256 { return u2s(A.d()) > u2s(B.d()) ? 1 : 0; }},
+		{{Instruction::EQ, {A, B}}, [=]() -> u256 { return A.d() == B.d() ? 1 : 0; }},
+		{{Instruction::ISZERO, {A}}, [=]() -> u256 { return A.d() == 0 ? 1 : 0; }},
+		{{Instruction::AND, {A, B}}, [=]{ return A.d() & B.d(); }},
+		{{Instruction::OR, {A, B}}, [=]{ return A.d() | B.d(); }},
+		{{Instruction::XOR, {A, B}}, [=]{ return A.d() ^ B.d(); }},
+		{{Instruction::BYTE, {A, B}}, [=]{ return A.d() >= 32 ? 0 : (B.d() >> unsigned(8 * (31 - A.d()))) & 0xff; }},
+		{{Instruction::ADDMOD, {A, B, C}}, [=]{ return C.d() == 0 ? 0 : u256((bigint(A.d()) + bigint(B.d())) % C.d()); }},
+		{{Instruction::MULMOD, {A, B, C}}, [=]{ return C.d() == 0 ? 0 : u256((bigint(A.d()) * bigint(B.d())) % C.d()); }},
+		{{Instruction::MULMOD, {A, B, C}}, [=]{ return A.d() * B.d(); }},
+		{{Instruction::SIGNEXTEND, {A, B}}, [=]() -> u256 {
+			if (A.d() >= 31)
+				return B.d();
+			unsigned testBit = unsigned(A.d()) * 8 + 7;
+			u256 mask = (u256(1) << testBit) - 1;
+			return u256(boost::multiprecision::bit_test(B.d(), testBit) ? B.d() | ~mask : B.d() & mask);
+		}},
+
+		// invariants involving known constants
+		{{Instruction::ADD, {X, 0}}, [=]{ return X; }},
+		{{Instruction::MUL, {X, 1}}, [=]{ return X; }},
+		{{Instruction::DIV, {X, 1}}, [=]{ return X; }},
+		{{Instruction::SDIV, {X, 1}}, [=]{ return X; }},
+		{{Instruction::OR, {X, 0}}, [=]{ return X; }},
+		{{Instruction::XOR, {X, 0}}, [=]{ return X; }},
+		{{Instruction::AND, {X, ~u256(0)}}, [=]{ return X; }},
+		{{Instruction::MUL, {X, 0}}, [=]{ return u256(0); }},
+		{{Instruction::DIV, {X, 0}}, [=]{ return u256(0); }},
+		{{Instruction::MOD, {X, 0}}, [=]{ return u256(0); }},
+		{{Instruction::MOD, {0, X}}, [=]{ return u256(0); }},
+		{{Instruction::AND, {X, 0}}, [=]{ return u256(0); }},
+		{{Instruction::OR, {X, ~u256(0)}}, [=]{ return ~u256(0); }},
+		// operations involving an expression and itself
+		{{Instruction::AND, {X, X}}, [=]{ return X; }},
+		{{Instruction::OR, {X, X}}, [=]{ return X; }},
+		{{Instruction::SUB, {X, X}}, [=]{ return u256(0); }},
+		{{Instruction::EQ, {X, X}}, [=]{ return u256(1); }},
+		{{Instruction::LT, {X, X}}, [=]{ return u256(0); }},
+		{{Instruction::SLT, {X, X}}, [=]{ return u256(0); }},
+		{{Instruction::GT, {X, X}}, [=]{ return u256(0); }},
+		{{Instruction::SGT, {X, X}}, [=]{ return u256(0); }},
+		{{Instruction::MOD, {X, X}}, [=]{ return u256(0); }},
+
+		{{Instruction::NOT, {{Instruction::NOT, {X}}}}, [=]{ return X; }},
+	};
+	// Double negation of opcodes with binary result
+	for (auto const& op: vector<Instruction>{
+		Instruction::EQ,
+		Instruction::LT,
+		Instruction::SLT,
+		Instruction::GT,
+		Instruction::SGT
+	})
+		m_rules.push_back({
+			{Instruction::ISZERO, {{Instruction::ISZERO, {{op, {X, Y}}}}}},
+			[=]() -> Pattern { return {op, {X, Y}}; }
+		});
+	m_rules.push_back({
+		{Instruction::ISZERO, {{Instruction::ISZERO, {{Instruction::ISZERO, {X}}}}}},
+		[=]() -> Pattern { return {Instruction::ISZERO, {X}}; }
+	});
+	// Associative operations
+	for (auto const& opFun: vector<pair<Instruction,function<u256(u256 const&,u256 const&)>>>{
+		{Instruction::ADD, plus<u256>()},
+		{Instruction::MUL, multiplies<u256>()},
+		{Instruction::AND, bit_and<u256>()},
+		{Instruction::OR, bit_or<u256>()},
+		{Instruction::XOR, bit_xor<u256>()}
+	})
+	{
+		auto op = opFun.first;
+		auto fun = opFun.second;
+		// Moving constants to the outside, order matters here!
+		// we need actions that return expressions (or patterns?) here, and we need also reversed rules
+		// (X+A)+B -> X+(A+B)
+		m_rules += vector<pair<Pattern, function<Pattern()>>>{{
+			{op, {{op, {X, A}}, B}},
+			[=]() -> Pattern { return {op, {X, fun(A.d(), B.d())}}; }
+		}, {
+		// X+(Y+A) -> (X+Y)+A
+			{op, {{op, {X, A}}, Y}},
+			[=]() -> Pattern { return {op, {{op, {X, Y}}, A}}; }
+		}, {
+		// For now, we still need explicit commutativity for the inner pattern
+			{op, {{op, {A, X}}, B}},
+			[=]() -> Pattern { return {op, {X, fun(A.d(), B.d())}}; }
+		}, {
+			{op, {{op, {A, X}}, Y}},
+			[=]() -> Pattern { return {op, {{op, {X, Y}}, A}}; }
+		}};
+	}
+	// move constants across subtractions
+	m_rules += vector<pair<Pattern, function<Pattern()>>>{
+		{
+			// X - A -> X + (-A)
+			{Instruction::SUB, {X, A}},
+			[=]() -> Pattern { return {Instruction::ADD, {X, 0 - A.d()}}; }
+		}, {
+			// (X + A) - Y -> (X - Y) + A
+			{Instruction::SUB, {{Instruction::ADD, {X, A}}, Y}},
+			[=]() -> Pattern { return {Instruction::ADD, {{Instruction::SUB, {X, Y}}, A}}; }
+		}, {
+			// (A + X) - Y -> (X - Y) + A
+			{Instruction::SUB, {{Instruction::ADD, {A, X}}, Y}},
+			[=]() -> Pattern { return {Instruction::ADD, {{Instruction::SUB, {X, Y}}, A}}; }
+		}, {
+			// X - (Y + A) -> (X - Y) + (-A)
+			{Instruction::SUB, {X, {Instruction::ADD, {Y, A}}}},
+			[=]() -> Pattern { return {Instruction::ADD, {{Instruction::SUB, {X, Y}}, 0 - A.d()}}; }
+		}, {
+			// X - (A + Y) -> (X - Y) + (-A)
+			{Instruction::SUB, {X, {Instruction::ADD, {A, Y}}}},
+			[=]() -> Pattern { return {Instruction::ADD, {{Instruction::SUB, {X, Y}}, 0 - A.d()}}; }
+		}
+	};
+}
+
+ExpressionClasses::Id ExpressionClasses::tryToSimplify(Expression const& _expr, bool _secondRun)
+{
+	static Rules rules;
+
+	if (
+		!_expr.item ||
+		_expr.item->type() != Operation ||
+		!SemanticInformation::isDeterministic(*_expr.item)
+	)
+		return -1;
+
+	for (auto const& rule: rules.rules())
+	{
+		rules.resetMatchGroups();
+		if (rule.first.matches(_expr, *this))
+		{
+			// Debug info
+			//cout << "Simplifying " << *_expr.item << "(";
+			//for (Id arg: _expr.arguments)
+			//	cout << fullDAGToString(arg) << ", ";
+			//cout << ")" << endl;
+			//cout << "with rule " << rule.first.toString() << endl;
+			//ExpressionTemplate t(rule.second());
+			//cout << "to " << rule.second().toString() << endl;
+			return rebuildExpression(ExpressionTemplate(rule.second(), _expr.item->location()));
+		}
+	}
+
+	if (!_secondRun && _expr.arguments.size() == 2 && SemanticInformation::isCommutativeOperation(*_expr.item))
+	{
+		Expression expr = _expr;
+		swap(expr.arguments[0], expr.arguments[1]);
+		return tryToSimplify(expr, true);
+	}
+
+	return -1;
+}
+
+ExpressionClasses::Id ExpressionClasses::rebuildExpression(ExpressionTemplate const& _template)
+{
+	if (_template.hasId)
+		return _template.id;
+
+	Ids arguments;
+	for (ExpressionTemplate const& t: _template.arguments)
+		arguments.push_back(rebuildExpression(t));
+	return find(_template.item, arguments);
+}
+
+
+Pattern::Pattern(Instruction _instruction, std::vector<Pattern> const& _arguments):
+	m_type(Operation),
+	m_requireDataMatch(true),
+	m_data(_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, ExpressionClasses const& _classes) const
+{
+	if (!matchesBaseItem(_expr.item))
+		return false;
+	if (m_matchGroup)
+	{
+		if (!m_matchGroups->count(m_matchGroup))
+			(*m_matchGroups)[m_matchGroup] = &_expr;
+		else if ((*m_matchGroups)[m_matchGroup]->id != _expr.id)
+			return false;
+	}
+	assertThrow(m_arguments.size() == 0 || _expr.arguments.size() == m_arguments.size(), OptimizerException, "");
+	for (size_t i = 0; i < m_arguments.size(); ++i)
+		if (!m_arguments[i].matches(_classes.representative(_expr.arguments[i]), _classes))
+			return false;
+	return true;
+}
+
+AssemblyItem Pattern::toAssemblyItem(SourceLocation const& _location) const
+{
+	return AssemblyItem(m_type, m_data, _location);
+}
+
+string Pattern::toString() const
+{
+	stringstream s;
+	switch (m_type)
+	{
+	case Operation:
+		s << instructionInfo(Instruction(unsigned(m_data))).name;
+		break;
+	case Push:
+		s << "PUSH " << hex << m_data;
+		break;
+	case UndefinedItem:
+		s << "ANY";
+		break;
+	default:
+		s << "t=" << dec << m_type << " d=" << hex << m_data;
+		break;
+	}
+	if (!m_requireDataMatch)
+		s << " ~";
+	if (m_matchGroup)
+		s << "[" << dec << m_matchGroup << "]";
+	s << "(";
+	for (Pattern const& p: m_arguments)
+		s << p.toString() << ", ";
+	s << ")";
+	return s.str();
+}
+
+bool Pattern::matchesBaseItem(AssemblyItem const* _item) const
+{
+	if (m_type == UndefinedItem)
+		return true;
+	if (!_item)
+		return false;
+	if (m_type != _item->type())
+		return false;
+	if (m_requireDataMatch && m_data != _item->data())
+		return false;
+	return true;
+}
+
+Pattern::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];
+}
+
+
+ExpressionTemplate::ExpressionTemplate(Pattern const& _pattern, SourceLocation const& _location)
+{
+	if (_pattern.matchGroup())
+	{
+		hasId = true;
+		id = _pattern.id();
+	}
+	else
+	{
+		hasId = false;
+		item = _pattern.toAssemblyItem(_location);
+	}
+	for (auto const& arg: _pattern.arguments())
+		arguments.push_back(ExpressionTemplate(arg, _location));
+}
+
+string ExpressionTemplate::toString() const
+{
+	stringstream s;
+	if (hasId)
+		s << id;
+	else
+		s << item;
+	s << "(";
+	for (auto const& arg: arguments)
+		s << arg.toString();
+	s << ")";
+	return s.str();
+}