Merge pull request #3456 from ethereum/simplifier

Use simplification rules also for IULIA

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;
+}
+
+}
+}