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Replace MOD with AND if constant is power of 2

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Alex Beregszaszi 2018-01-04 12:05:01 +00:00
parent 954903b505
commit 037b97ef4a
1 changed files with 11 additions and 0 deletions
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11
libevmasm/RuleList.h
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@ -153,6 +153,17 @@ std::vector<SimplificationRule<Pattern>> simplificationRuleList(
{{Instruction::OR, {{Instruction::NOT, {X}}, X}}, [=]{ return ~u256(0); }, true},
};
// Replace MOD X, <power-of-two> with AND X, <power-of-two> - 1
for (size_t i = 0; i < 256; ++i)
{
u256 value = u256(1) << i;
rules.push_back({
{Instruction::MOD, {X, value}},
[=]() -> Pattern { return {Instruction::AND, {X, value - 1}}; },
false
});
}
// Double negation of opcodes with boolean result
for (auto const& op: std::vector<Instruction>{
Instruction::EQ,