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Diffstat (limited to 'libevmasm/RuleList.h')
| -rw-r--r-- | libevmasm/RuleList.h | 255 |
1 files changed, 255 insertions, 0 deletions
diff --git a/libevmasm/RuleList.h b/libevmasm/RuleList.h new file mode 100644 index 00000000..2312d673 --- /dev/null +++ b/libevmasm/RuleList.h @@ -0,0 +1,255 @@ +/* + 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/>. +*/ +/** + * @date 2018 + * Templatized list of simplification rules. + */ + +#pragma once + +#include <vector> +#include <functional> + +#include <libevmasm/Instruction.h> +#include <libevmasm/SimplificationRule.h> + +#include <libdevcore/CommonData.h> + +namespace dev +{ +namespace solidity +{ + +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)); +} + +/// @returns a list of simplification rules given certain match placeholders. +/// A, B and C should represent constants, X and Y arbitrary expressions. +/// The simplifications should neven change the order of evaluation of +/// arbitrary operations. +template <class Pattern> +std::vector<SimplificationRule<Pattern>> simplificationRuleList( + Pattern A, + Pattern B, + Pattern C, + Pattern X, + Pattern Y +) +{ + std::vector<SimplificationRule<Pattern>> rules; + rules += std::vector<SimplificationRule<Pattern>>{ + // arithmetics on constants + {{Instruction::ADD, {A, B}}, [=]{ return A.d() + B.d(); }, false}, + {{Instruction::MUL, {A, B}}, [=]{ return A.d() * B.d(); }, false}, + {{Instruction::SUB, {A, B}}, [=]{ return A.d() - B.d(); }, false}, + {{Instruction::DIV, {A, B}}, [=]{ return B.d() == 0 ? 0 : divWorkaround(A.d(), B.d()); }, false}, + {{Instruction::SDIV, {A, B}}, [=]{ return B.d() == 0 ? 0 : s2u(divWorkaround(u2s(A.d()), u2s(B.d()))); }, false}, + {{Instruction::MOD, {A, B}}, [=]{ return B.d() == 0 ? 0 : modWorkaround(A.d(), B.d()); }, false}, + {{Instruction::SMOD, {A, B}}, [=]{ return B.d() == 0 ? 0 : s2u(modWorkaround(u2s(A.d()), u2s(B.d()))); }, false}, + {{Instruction::EXP, {A, B}}, [=]{ return u256(boost::multiprecision::powm(bigint(A.d()), bigint(B.d()), bigint(1) << 256)); }, false}, + {{Instruction::NOT, {A}}, [=]{ return ~A.d(); }, false}, + {{Instruction::LT, {A, B}}, [=]() -> u256 { return A.d() < B.d() ? 1 : 0; }, false}, + {{Instruction::GT, {A, B}}, [=]() -> u256 { return A.d() > B.d() ? 1 : 0; }, false}, + {{Instruction::SLT, {A, B}}, [=]() -> u256 { return u2s(A.d()) < u2s(B.d()) ? 1 : 0; }, false}, + {{Instruction::SGT, {A, B}}, [=]() -> u256 { return u2s(A.d()) > u2s(B.d()) ? 1 : 0; }, false}, + {{Instruction::EQ, {A, B}}, [=]() -> u256 { return A.d() == B.d() ? 1 : 0; }, false}, + {{Instruction::ISZERO, {A}}, [=]() -> u256 { return A.d() == 0 ? 1 : 0; }, false}, + {{Instruction::AND, {A, B}}, [=]{ return A.d() & B.d(); }, false}, + {{Instruction::OR, {A, B}}, [=]{ return A.d() | B.d(); }, false}, + {{Instruction::XOR, {A, B}}, [=]{ return A.d() ^ B.d(); }, false}, + {{Instruction::BYTE, {A, B}}, [=]{ return A.d() >= 32 ? 0 : (B.d() >> unsigned(8 * (31 - A.d()))) & 0xff; }, false}, + {{Instruction::ADDMOD, {A, B, C}}, [=]{ return C.d() == 0 ? 0 : u256((bigint(A.d()) + bigint(B.d())) % C.d()); }, false}, + {{Instruction::MULMOD, {A, B, C}}, [=]{ return C.d() == 0 ? 0 : u256((bigint(A.d()) * bigint(B.d())) % C.d()); }, false}, + {{Instruction::MULMOD, {A, B, C}}, [=]{ return A.d() * B.d(); }, false}, + {{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); + }, false}, + + // invariants involving known constants + {{Instruction::ADD, {X, 0}}, [=]{ return X; }, false}, + {{Instruction::ADD, {0, X}}, [=]{ return X; }, false}, + {{Instruction::SUB, {X, 0}}, [=]{ return X; }, false}, + {{Instruction::MUL, {X, 0}}, [=]{ return u256(0); }, true}, + {{Instruction::MUL, {0, X}}, [=]{ return u256(0); }, true}, + {{Instruction::MUL, {X, 1}}, [=]{ return X; }, false}, + {{Instruction::MUL, {1, X}}, [=]{ return X; }, false}, + {{Instruction::MUL, {X, u256(-1)}}, [=]() -> Pattern { return {Instruction::SUB, {0, X}}; }, false}, + {{Instruction::MUL, {u256(-1), X}}, [=]() -> Pattern { return {Instruction::SUB, {0, X}}; }, false}, + {{Instruction::DIV, {X, 0}}, [=]{ return u256(0); }, true}, + {{Instruction::DIV, {0, X}}, [=]{ return u256(0); }, true}, + {{Instruction::DIV, {X, 1}}, [=]{ return X; }, false}, + {{Instruction::SDIV, {X, 0}}, [=]{ return u256(0); }, true}, + {{Instruction::SDIV, {0, X}}, [=]{ return u256(0); }, true}, + {{Instruction::SDIV, {X, 1}}, [=]{ return X; }, false}, + {{Instruction::AND, {X, ~u256(0)}}, [=]{ return X; }, false}, + {{Instruction::AND, {~u256(0), X}}, [=]{ return X; }, false}, + {{Instruction::AND, {X, 0}}, [=]{ return u256(0); }, true}, + {{Instruction::AND, {0, X}}, [=]{ return u256(0); }, true}, + {{Instruction::OR, {X, 0}}, [=]{ return X; }, false}, + {{Instruction::OR, {0, X}}, [=]{ return X; }, false}, + {{Instruction::OR, {X, ~u256(0)}}, [=]{ return ~u256(0); }, true}, + {{Instruction::OR, {~u256(0), X}}, [=]{ return ~u256(0); }, true}, + {{Instruction::XOR, {X, 0}}, [=]{ return X; }, false}, + {{Instruction::XOR, {0, X}}, [=]{ return X; }, false}, + {{Instruction::MOD, {X, 0}}, [=]{ return u256(0); }, true}, + {{Instruction::MOD, {0, X}}, [=]{ return u256(0); }, true}, + {{Instruction::EQ, {X, 0}}, [=]() -> Pattern { return {Instruction::ISZERO, {X}}; }, false }, + {{Instruction::EQ, {0, X}}, [=]() -> Pattern { return {Instruction::ISZERO, {X}}; }, false }, + + // operations involving an expression and itself + {{Instruction::AND, {X, X}}, [=]{ return X; }, true}, + {{Instruction::OR, {X, X}}, [=]{ return X; }, true}, + {{Instruction::XOR, {X, X}}, [=]{ return u256(0); }, true}, + {{Instruction::SUB, {X, X}}, [=]{ return u256(0); }, true}, + {{Instruction::EQ, {X, X}}, [=]{ return u256(1); }, true}, + {{Instruction::LT, {X, X}}, [=]{ return u256(0); }, true}, + {{Instruction::SLT, {X, X}}, [=]{ return u256(0); }, true}, + {{Instruction::GT, {X, X}}, [=]{ return u256(0); }, true}, + {{Instruction::SGT, {X, X}}, [=]{ return u256(0); }, true}, + {{Instruction::MOD, {X, X}}, [=]{ return u256(0); }, true}, + + // logical instruction combinations + {{Instruction::NOT, {{Instruction::NOT, {X}}}}, [=]{ return X; }, false}, + {{Instruction::XOR, {X, {Instruction::XOR, {X, Y}}}}, [=]{ return Y; }, true}, + {{Instruction::XOR, {X, {Instruction::XOR, {Y, X}}}}, [=]{ return Y; }, true}, + {{Instruction::XOR, {{Instruction::XOR, {X, Y}}, X}}, [=]{ return Y; }, true}, + {{Instruction::XOR, {{Instruction::XOR, {Y, X}}, X}}, [=]{ return Y; }, true}, + {{Instruction::OR, {X, {Instruction::AND, {X, Y}}}}, [=]{ return X; }, true}, + {{Instruction::OR, {X, {Instruction::AND, {Y, X}}}}, [=]{ return X; }, true}, + {{Instruction::OR, {{Instruction::AND, {X, Y}}, X}}, [=]{ return X; }, true}, + {{Instruction::OR, {{Instruction::AND, {Y, X}}, X}}, [=]{ return X; }, true}, + {{Instruction::AND, {X, {Instruction::OR, {X, Y}}}}, [=]{ return X; }, true}, + {{Instruction::AND, {X, {Instruction::OR, {Y, X}}}}, [=]{ return X; }, true}, + {{Instruction::AND, {{Instruction::OR, {X, Y}}, X}}, [=]{ return X; }, true}, + {{Instruction::AND, {{Instruction::OR, {Y, X}}, X}}, [=]{ return X; }, true}, + {{Instruction::AND, {X, {Instruction::NOT, {X}}}}, [=]{ return u256(0); }, true}, + {{Instruction::AND, {{Instruction::NOT, {X}}, X}}, [=]{ return u256(0); }, true}, + {{Instruction::OR, {X, {Instruction::NOT, {X}}}}, [=]{ return ~u256(0); }, true}, + {{Instruction::OR, {{Instruction::NOT, {X}}, X}}, [=]{ return ~u256(0); }, true}, + }; + + // Double negation of opcodes with boolean result + for (auto const& op: std::vector<Instruction>{ + Instruction::EQ, + Instruction::LT, + Instruction::SLT, + Instruction::GT, + Instruction::SGT + }) + rules.push_back({ + {Instruction::ISZERO, {{Instruction::ISZERO, {{op, {X, Y}}}}}}, + [=]() -> Pattern { return {op, {X, Y}}; }, + false + }); + + rules.push_back({ + {Instruction::ISZERO, {{Instruction::ISZERO, {{Instruction::ISZERO, {X}}}}}}, + [=]() -> Pattern { return {Instruction::ISZERO, {X}}; }, + false + }); + + rules.push_back({ + {Instruction::ISZERO, {{Instruction::XOR, {X, Y}}}}, + [=]() -> Pattern { return { Instruction::EQ, {X, Y} }; }, + false + }); + + // Associative operations + for (auto const& opFun: std::vector<std::pair<Instruction,std::function<u256(u256 const&,u256 const&)>>>{ + {Instruction::ADD, std::plus<u256>()}, + {Instruction::MUL, std::multiplies<u256>()}, + {Instruction::AND, std::bit_and<u256>()}, + {Instruction::OR, std::bit_or<u256>()}, + {Instruction::XOR, std::bit_xor<u256>()} + }) + { + auto op = opFun.first; + auto fun = opFun.second; + // Moving constants to the outside, order matters here - we first add rules + // for constants and then for non-constants. + // xa can be (X, A) or (A, X) + for (auto xa: {std::vector<Pattern>{X, A}, std::vector<Pattern>{A, X}}) + { + rules += std::vector<SimplificationRule<Pattern>>{{ + // (X+A)+B -> X+(A+B) + {op, {{op, xa}, B}}, + [=]() -> Pattern { return {op, {X, fun(A.d(), B.d())}}; }, + false + }, { + // (X+A)+Y -> (X+Y)+A + {op, {{op, xa}, Y}}, + [=]() -> Pattern { return {op, {{op, {X, Y}}, A}}; }, + false + }, { + // B+(X+A) -> X+(A+B) + {op, {B, {op, xa}}}, + [=]() -> Pattern { return {op, {X, fun(A.d(), B.d())}}; }, + false + }, { + // Y+(X+A) -> (Y+X)+A + {op, {Y, {op, xa}}}, + [=]() -> Pattern { return {op, {{op, {Y, X}}, A}}; }, + false + }}; + } + } + + // move constants across subtractions + rules += std::vector<SimplificationRule<Pattern>>{ + { + // X - A -> X + (-A) + {Instruction::SUB, {X, A}}, + [=]() -> Pattern { return {Instruction::ADD, {X, 0 - A.d()}}; }, + false + }, { + // (X + A) - Y -> (X - Y) + A + {Instruction::SUB, {{Instruction::ADD, {X, A}}, Y}}, + [=]() -> Pattern { return {Instruction::ADD, {{Instruction::SUB, {X, Y}}, A}}; }, + false + }, { + // (A + X) - Y -> (X - Y) + A + {Instruction::SUB, {{Instruction::ADD, {A, X}}, Y}}, + [=]() -> Pattern { return {Instruction::ADD, {{Instruction::SUB, {X, Y}}, A}}; }, + false + }, { + // X - (Y + A) -> (X - Y) + (-A) + {Instruction::SUB, {X, {Instruction::ADD, {Y, A}}}}, + [=]() -> Pattern { return {Instruction::ADD, {{Instruction::SUB, {X, Y}}, 0 - A.d()}}; }, + false + }, { + // X - (A + Y) -> (X - Y) + (-A) + {Instruction::SUB, {X, {Instruction::ADD, {A, Y}}}}, + [=]() -> Pattern { return {Instruction::ADD, {{Instruction::SUB, {X, Y}}, 0 - A.d()}}; }, + false + } + }; + return rules; +} + +} +} |