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https://github.com/ethereum/solidity
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Explicitly add reversed operands for commutative operations.
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chriseth
parent
9eea3f29ba
commit
295f8c07ad
@ -43,11 +43,6 @@ template <class S> S modWorkaround(S const& _a, S const& _b)
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return (S)(bigint(_a) % bigint(_b));
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}
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// TODO: Add a parameter that will cause rules with swapped arguments
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// to be added explicitly. This is needed by the new optimizer, but not
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// by the old. The new optimizer requires that the order of arbitrary
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// expressions is not altered.
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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 third element in the tuple is a boolean flag that indicates whether
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@ -96,11 +91,16 @@ std::vector<std::tuple<Pattern, std::function<Pattern()>, bool>> simplificationR
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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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// invariants involving known constants (commutative instructions will be checked with swapped operants too)
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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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@ -108,13 +108,19 @@ std::vector<std::tuple<Pattern, std::function<Pattern()>, bool>> simplificationR
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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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@ -130,14 +136,25 @@ std::vector<std::tuple<Pattern, std::function<Pattern()>, bool>> simplificationR
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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::OR, {{{X}, {Instruction::AND, {X, Y}}}}}, [=]{ 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::NOT, {X}}}}}, [=]{ return u256(0); }, true},
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{{Instruction::OR, {{{X}, {Instruction::NOT, {X}}}}}, [=]{ return ~u256(0); }, true},
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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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// Double negation of opcodes with binary result
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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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@ -174,28 +191,33 @@ std::vector<std::tuple<Pattern, std::function<Pattern()>, bool>> simplificationR
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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!
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// we need actions that return expressions (or patterns?) here, and we need also reversed rules
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// (X+A)+B -> X+(A+B)
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rules += std::vector<std::tuple<Pattern, std::function<Pattern()>, bool>>{{
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{op, {{op, {X, A}}, 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+(Y+A) -> (X+Y)+A
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{op, {{op, {X, A}}, 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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// For now, we still need explicit commutativity for the inner pattern
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{op, {{op, {A, X}}, 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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{op, {{op, {A, X}}, 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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// 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<std::tuple<Pattern, std::function<Pattern()>, bool>>{{
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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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