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Diffstat (limited to 'libevmasm/SimplificationRules.cpp')
| -rw-r--r-- | libevmasm/SimplificationRules.cpp | 363 |
1 files changed, 363 insertions, 0 deletions
diff --git a/libevmasm/SimplificationRules.cpp b/libevmasm/SimplificationRules.cpp new file mode 100644 index 00000000..bb950400 --- /dev/null +++ b/libevmasm/SimplificationRules.cpp @@ -0,0 +1,363 @@ +/* + 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/>. +*/ +/** + * @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> +#include <libevmasm/SimplificationRules.h> + +using namespace std; +using namespace dev; +using namespace dev::eth; + + +pair<Pattern, function<Pattern()> > const* Rules::findFirstMatch( + Expression const& _expr, + ExpressionClasses const& _classes +) +{ + resetMatchGroups(); + + assertThrow(_expr.item, OptimizerException, ""); + for (auto const& rule: m_rules[byte(_expr.item->instruction())]) + { + if (rule.first.matches(_expr, _classes)) + return &rule; + } + return nullptr; +} + +void Rules::addRules(std::vector<std::pair<Pattern, std::function<Pattern ()> > > const& _rules) +{ + for (auto const& r: _rules) + addRule(r); +} + +void Rules::addRule(std::pair<Pattern, std::function<Pattern()> > const& _rule) +{ + m_rules[byte(_rule.first.instruction())].push_back(_rule); +} + +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); + + addRules(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::SUB, {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::AND, {X, 0}}, [=]{ return u256(0); }}, + {{Instruction::MUL, {X, 0}}, [=]{ return u256(0); }}, + {{Instruction::DIV, {X, 0}}, [=]{ return u256(0); }}, + {{Instruction::DIV, {0, X}}, [=]{ return u256(0); }}, + {{Instruction::MOD, {X, 0}}, [=]{ return u256(0); }}, + {{Instruction::MOD, {0, X}}, [=]{ return u256(0); }}, + {{Instruction::OR, {X, ~u256(0)}}, [=]{ return ~u256(0); }}, + {{Instruction::EQ, {X, 0}}, [=]() -> Pattern { return {Instruction::ISZERO, {X}}; } }, + // operations involving an expression and itself + {{Instruction::AND, {X, X}}, [=]{ return X; }}, + {{Instruction::OR, {X, X}}, [=]{ return X; }}, + {{Instruction::XOR, {X, X}}, [=]{ return u256(0); }}, + {{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; }}, + {{Instruction::XOR, {{{X}, {Instruction::XOR, {X, Y}}}}}, [=]{ return Y; }}, + {{Instruction::OR, {{{X}, {Instruction::AND, {X, Y}}}}}, [=]{ return X; }}, + {{Instruction::AND, {{{X}, {Instruction::OR, {X, Y}}}}}, [=]{ return X; }}, + {{Instruction::AND, {{{X}, {Instruction::NOT, {X}}}}}, [=]{ return u256(0); }}, + {{Instruction::OR, {{{X}, {Instruction::NOT, {X}}}}}, [=]{ return ~u256(0); }}, + }); + // Double negation of opcodes with binary result + for (auto const& op: vector<Instruction>{ + Instruction::EQ, + Instruction::LT, + Instruction::SLT, + Instruction::GT, + Instruction::SGT + }) + addRule({ + {Instruction::ISZERO, {{Instruction::ISZERO, {{op, {X, Y}}}}}}, + [=]() -> Pattern { return {op, {X, Y}}; } + }); + addRule({ + {Instruction::ISZERO, {{Instruction::ISZERO, {{Instruction::ISZERO, {X}}}}}}, + [=]() -> Pattern { return {Instruction::ISZERO, {X}}; } + }); + addRule({ + {Instruction::ISZERO, {{Instruction::XOR, {X, Y}}}}, + [=]() -> Pattern { return { Instruction::EQ, {X, Y} }; } + }); + // 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) + addRules(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 + addRules(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()}}; } + } + }); +} + +Pattern::Pattern(Instruction _instruction, std::vector<Pattern> const& _arguments): + m_type(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, 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 +{ + if (m_type == Operation) + return AssemblyItem(m_instruction, _location); + else + return AssemblyItem(m_type, data(), _location); +} + +string Pattern::toString() const +{ + stringstream s; + switch (m_type) + { + case Operation: + s << instructionInfo(m_instruction).name; + break; + case Push: + s << "PUSH " << hex << data(); + break; + case UndefinedItem: + s << "ANY"; + break; + default: + s << "t=" << dec << m_type << " d=" << hex << 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; + else if (m_type == Operation) + return m_instruction == _item->instruction(); + else if (m_requireDataMatch) + return data() == _item->data(); + 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]; +} + +u256 const& Pattern::data() const +{ + assertThrow(m_data, OptimizerException, ""); + return *m_data; +} + +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(); +} |