mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
277 lines
11 KiB
C++
277 lines
11 KiB
C++
/*
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This file is part of solidity.
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solidity is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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solidity is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with solidity. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* @date 2018
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* Templatized list of simplification rules.
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*/
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#pragma once
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#include <vector>
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#include <functional>
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#include <libevmasm/Instruction.h>
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#include <libevmasm/SimplificationRule.h>
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#include <libdevcore/CommonData.h>
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namespace dev
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{
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namespace solidity
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{
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template <class S> S divWorkaround(S const& _a, S const& _b)
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{
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return (S)(bigint(_a) / bigint(_b));
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}
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template <class S> S modWorkaround(S const& _a, S const& _b)
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{
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return (S)(bigint(_a) % bigint(_b));
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}
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/// @returns a list of simplification rules given certain match placeholders.
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/// A, B and C should represent constants, X and Y arbitrary expressions.
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/// The simplifications should neven change the order of evaluation of
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/// arbitrary operations.
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template <class Pattern>
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std::vector<SimplificationRule<Pattern>> simplificationRuleList(
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Pattern A,
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Pattern B,
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Pattern C,
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Pattern X,
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Pattern Y
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)
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{
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std::vector<SimplificationRule<Pattern>> rules;
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rules += std::vector<SimplificationRule<Pattern>>{
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// arithmetics on constants
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{{Instruction::ADD, {A, B}}, [=]{ return A.d() + B.d(); }, false},
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{{Instruction::MUL, {A, B}}, [=]{ return A.d() * B.d(); }, false},
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{{Instruction::SUB, {A, B}}, [=]{ return A.d() - B.d(); }, false},
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{{Instruction::DIV, {A, B}}, [=]{ return B.d() == 0 ? 0 : divWorkaround(A.d(), B.d()); }, false},
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{{Instruction::SDIV, {A, B}}, [=]{ return B.d() == 0 ? 0 : s2u(divWorkaround(u2s(A.d()), u2s(B.d()))); }, false},
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{{Instruction::MOD, {A, B}}, [=]{ return B.d() == 0 ? 0 : modWorkaround(A.d(), B.d()); }, false},
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{{Instruction::SMOD, {A, B}}, [=]{ return B.d() == 0 ? 0 : s2u(modWorkaround(u2s(A.d()), u2s(B.d()))); }, false},
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{{Instruction::EXP, {A, B}}, [=]{ return u256(boost::multiprecision::powm(bigint(A.d()), bigint(B.d()), bigint(1) << 256)); }, false},
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{{Instruction::NOT, {A}}, [=]{ return ~A.d(); }, false},
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{{Instruction::LT, {A, B}}, [=]() -> u256 { return A.d() < B.d() ? 1 : 0; }, false},
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{{Instruction::GT, {A, B}}, [=]() -> u256 { return A.d() > B.d() ? 1 : 0; }, false},
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{{Instruction::SLT, {A, B}}, [=]() -> u256 { return u2s(A.d()) < u2s(B.d()) ? 1 : 0; }, false},
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{{Instruction::SGT, {A, B}}, [=]() -> u256 { return u2s(A.d()) > u2s(B.d()) ? 1 : 0; }, false},
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{{Instruction::EQ, {A, B}}, [=]() -> u256 { return A.d() == B.d() ? 1 : 0; }, false},
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{{Instruction::ISZERO, {A}}, [=]() -> u256 { return A.d() == 0 ? 1 : 0; }, false},
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{{Instruction::AND, {A, B}}, [=]{ return A.d() & B.d(); }, false},
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{{Instruction::OR, {A, B}}, [=]{ return A.d() | B.d(); }, false},
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{{Instruction::XOR, {A, B}}, [=]{ return A.d() ^ B.d(); }, false},
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{{Instruction::BYTE, {A, B}}, [=]{ return A.d() >= 32 ? 0 : (B.d() >> unsigned(8 * (31 - A.d()))) & 0xff; }, false},
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{{Instruction::ADDMOD, {A, B, C}}, [=]{ return C.d() == 0 ? 0 : u256((bigint(A.d()) + bigint(B.d())) % C.d()); }, false},
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{{Instruction::MULMOD, {A, B, C}}, [=]{ return C.d() == 0 ? 0 : u256((bigint(A.d()) * bigint(B.d())) % C.d()); }, false},
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{{Instruction::MULMOD, {A, B, C}}, [=]{ return A.d() * B.d(); }, false},
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{{Instruction::SIGNEXTEND, {A, B}}, [=]() -> u256 {
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if (A.d() >= 31)
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return B.d();
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unsigned testBit = unsigned(A.d()) * 8 + 7;
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u256 mask = (u256(1) << testBit) - 1;
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return u256(boost::multiprecision::bit_test(B.d(), testBit) ? B.d() | ~mask : B.d() & mask);
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}, false},
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{{Instruction::SHL, {A, B}}, [=]{
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if (A.d() > 255)
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return u256(0);
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return u256(bigint(B.d()) << unsigned(A.d()));
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}, false},
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{{Instruction::SHR, {A, B}}, [=]{
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if (A.d() > 255)
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return u256(0);
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return B.d() >> unsigned(A.d());
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}, false},
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// invariants involving known constants
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{{Instruction::ADD, {X, 0}}, [=]{ return X; }, false},
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{{Instruction::ADD, {0, X}}, [=]{ return X; }, false},
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{{Instruction::SUB, {X, 0}}, [=]{ return X; }, false},
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{{Instruction::MUL, {X, 0}}, [=]{ return u256(0); }, true},
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{{Instruction::MUL, {0, X}}, [=]{ return u256(0); }, true},
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{{Instruction::MUL, {X, 1}}, [=]{ return X; }, false},
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{{Instruction::MUL, {1, X}}, [=]{ return X; }, false},
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{{Instruction::MUL, {X, u256(-1)}}, [=]() -> Pattern { return {Instruction::SUB, {0, X}}; }, false},
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{{Instruction::MUL, {u256(-1), X}}, [=]() -> Pattern { return {Instruction::SUB, {0, X}}; }, false},
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{{Instruction::DIV, {X, 0}}, [=]{ return u256(0); }, true},
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{{Instruction::DIV, {0, X}}, [=]{ return u256(0); }, true},
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{{Instruction::DIV, {X, 1}}, [=]{ return X; }, false},
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{{Instruction::SDIV, {X, 0}}, [=]{ return u256(0); }, true},
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{{Instruction::SDIV, {0, X}}, [=]{ return u256(0); }, true},
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{{Instruction::SDIV, {X, 1}}, [=]{ return X; }, false},
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{{Instruction::AND, {X, ~u256(0)}}, [=]{ return X; }, false},
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{{Instruction::AND, {~u256(0), X}}, [=]{ return X; }, false},
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{{Instruction::AND, {X, 0}}, [=]{ return u256(0); }, true},
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{{Instruction::AND, {0, X}}, [=]{ return u256(0); }, true},
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{{Instruction::OR, {X, 0}}, [=]{ return X; }, false},
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{{Instruction::OR, {0, X}}, [=]{ return X; }, false},
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{{Instruction::OR, {X, ~u256(0)}}, [=]{ return ~u256(0); }, true},
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{{Instruction::OR, {~u256(0), X}}, [=]{ return ~u256(0); }, true},
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{{Instruction::XOR, {X, 0}}, [=]{ return X; }, false},
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{{Instruction::XOR, {0, X}}, [=]{ return X; }, false},
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{{Instruction::MOD, {X, 0}}, [=]{ return u256(0); }, true},
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{{Instruction::MOD, {0, X}}, [=]{ return u256(0); }, true},
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{{Instruction::EQ, {X, 0}}, [=]() -> Pattern { return {Instruction::ISZERO, {X}}; }, false },
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{{Instruction::EQ, {0, X}}, [=]() -> Pattern { return {Instruction::ISZERO, {X}}; }, false },
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// operations involving an expression and itself
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{{Instruction::AND, {X, X}}, [=]{ return X; }, true},
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{{Instruction::OR, {X, X}}, [=]{ return X; }, true},
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{{Instruction::XOR, {X, X}}, [=]{ return u256(0); }, true},
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{{Instruction::SUB, {X, X}}, [=]{ return u256(0); }, true},
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{{Instruction::EQ, {X, X}}, [=]{ return u256(1); }, true},
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{{Instruction::LT, {X, X}}, [=]{ return u256(0); }, true},
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{{Instruction::SLT, {X, X}}, [=]{ return u256(0); }, true},
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{{Instruction::GT, {X, X}}, [=]{ return u256(0); }, true},
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{{Instruction::SGT, {X, X}}, [=]{ return u256(0); }, true},
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{{Instruction::MOD, {X, X}}, [=]{ return u256(0); }, true},
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// logical instruction combinations
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{{Instruction::NOT, {{Instruction::NOT, {X}}}}, [=]{ return X; }, false},
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{{Instruction::XOR, {X, {Instruction::XOR, {X, Y}}}}, [=]{ return Y; }, true},
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{{Instruction::XOR, {X, {Instruction::XOR, {Y, X}}}}, [=]{ return Y; }, true},
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{{Instruction::XOR, {{Instruction::XOR, {X, Y}}, X}}, [=]{ return Y; }, true},
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{{Instruction::XOR, {{Instruction::XOR, {Y, X}}, X}}, [=]{ return Y; }, true},
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{{Instruction::OR, {X, {Instruction::AND, {X, Y}}}}, [=]{ return X; }, true},
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{{Instruction::OR, {X, {Instruction::AND, {Y, X}}}}, [=]{ return X; }, true},
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{{Instruction::OR, {{Instruction::AND, {X, Y}}, X}}, [=]{ return X; }, true},
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{{Instruction::OR, {{Instruction::AND, {Y, X}}, X}}, [=]{ return X; }, true},
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{{Instruction::AND, {X, {Instruction::OR, {X, Y}}}}, [=]{ return X; }, true},
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{{Instruction::AND, {X, {Instruction::OR, {Y, X}}}}, [=]{ return X; }, true},
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{{Instruction::AND, {{Instruction::OR, {X, Y}}, X}}, [=]{ return X; }, true},
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{{Instruction::AND, {{Instruction::OR, {Y, X}}, X}}, [=]{ return X; }, true},
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{{Instruction::AND, {X, {Instruction::NOT, {X}}}}, [=]{ return u256(0); }, true},
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{{Instruction::AND, {{Instruction::NOT, {X}}, X}}, [=]{ return u256(0); }, true},
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{{Instruction::OR, {X, {Instruction::NOT, {X}}}}, [=]{ return ~u256(0); }, true},
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{{Instruction::OR, {{Instruction::NOT, {X}}, X}}, [=]{ return ~u256(0); }, true},
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};
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// Replace MOD X, <power-of-two> with AND X, <power-of-two> - 1
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for (size_t i = 0; i < 256; ++i)
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{
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u256 value = u256(1) << i;
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rules.push_back({
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{Instruction::MOD, {X, value}},
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[=]() -> Pattern { return {Instruction::AND, {X, value - 1}}; },
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false
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});
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}
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// Double negation of opcodes with boolean result
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for (auto const& op: std::vector<Instruction>{
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Instruction::EQ,
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Instruction::LT,
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Instruction::SLT,
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Instruction::GT,
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Instruction::SGT
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})
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rules.push_back({
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{Instruction::ISZERO, {{Instruction::ISZERO, {{op, {X, Y}}}}}},
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[=]() -> Pattern { return {op, {X, Y}}; },
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false
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});
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rules.push_back({
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{Instruction::ISZERO, {{Instruction::ISZERO, {{Instruction::ISZERO, {X}}}}}},
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[=]() -> Pattern { return {Instruction::ISZERO, {X}}; },
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false
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});
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rules.push_back({
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{Instruction::ISZERO, {{Instruction::XOR, {X, Y}}}},
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[=]() -> Pattern { return { Instruction::EQ, {X, Y} }; },
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false
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});
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// Associative operations
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for (auto const& opFun: std::vector<std::pair<Instruction,std::function<u256(u256 const&,u256 const&)>>>{
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{Instruction::ADD, std::plus<u256>()},
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{Instruction::MUL, std::multiplies<u256>()},
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{Instruction::AND, std::bit_and<u256>()},
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{Instruction::OR, std::bit_or<u256>()},
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{Instruction::XOR, std::bit_xor<u256>()}
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})
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{
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auto op = opFun.first;
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auto fun = opFun.second;
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// Moving constants to the outside, order matters here - we first add rules
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// for constants and then for non-constants.
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// xa can be (X, A) or (A, X)
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for (auto xa: {std::vector<Pattern>{X, A}, std::vector<Pattern>{A, X}})
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{
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rules += std::vector<SimplificationRule<Pattern>>{{
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// (X+A)+B -> X+(A+B)
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{op, {{op, xa}, B}},
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[=]() -> Pattern { return {op, {X, fun(A.d(), B.d())}}; },
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false
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}, {
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// (X+A)+Y -> (X+Y)+A
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{op, {{op, xa}, Y}},
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[=]() -> Pattern { return {op, {{op, {X, Y}}, A}}; },
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false
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}, {
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// B+(X+A) -> X+(A+B)
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{op, {B, {op, xa}}},
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[=]() -> Pattern { return {op, {X, fun(A.d(), B.d())}}; },
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false
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}, {
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// Y+(X+A) -> (Y+X)+A
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{op, {Y, {op, xa}}},
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[=]() -> Pattern { return {op, {{op, {Y, X}}, A}}; },
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false
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}};
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}
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}
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// move constants across subtractions
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rules += std::vector<SimplificationRule<Pattern>>{
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{
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// X - A -> X + (-A)
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{Instruction::SUB, {X, A}},
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[=]() -> Pattern { return {Instruction::ADD, {X, 0 - A.d()}}; },
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false
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}, {
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// (X + A) - Y -> (X - Y) + A
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{Instruction::SUB, {{Instruction::ADD, {X, A}}, Y}},
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[=]() -> Pattern { return {Instruction::ADD, {{Instruction::SUB, {X, Y}}, A}}; },
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false
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}, {
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// (A + X) - Y -> (X - Y) + A
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{Instruction::SUB, {{Instruction::ADD, {A, X}}, Y}},
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[=]() -> Pattern { return {Instruction::ADD, {{Instruction::SUB, {X, Y}}, A}}; },
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false
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}, {
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// X - (Y + A) -> (X - Y) + (-A)
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{Instruction::SUB, {X, {Instruction::ADD, {Y, A}}}},
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[=]() -> Pattern { return {Instruction::ADD, {{Instruction::SUB, {X, Y}}, 0 - A.d()}}; },
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false
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}, {
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// X - (A + Y) -> (X - Y) + (-A)
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{Instruction::SUB, {X, {Instruction::ADD, {A, Y}}}},
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[=]() -> Pattern { return {Instruction::ADD, {{Instruction::SUB, {X, Y}}, 0 - A.d()}}; },
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false
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}
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};
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return rules;
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}
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}
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}
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