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| author | Alex Beregszaszi <alex@rtfs.hu> | 2018-01-04 20:05:01 +0800 |
|---|---|---|
| committer | Alex Beregszaszi <alex@rtfs.hu> | 2018-02-13 06:47:04 +0800 |
| commit | 037b97ef4a53c30f2800777a88d754a898bccc2b (patch) | |
| tree | 18e053b78cf0e6f02baabc1f549568fd54567ea6 | |
| parent | 954903b50540456906fd7ba909d7d663e2bd7a7f (diff) | |
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Replace MOD with AND if constant is power of 2
| -rw-r--r-- | libevmasm/RuleList.h | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/libevmasm/RuleList.h b/libevmasm/RuleList.h index 2312d673..da522cec 100644 --- a/libevmasm/RuleList.h +++ b/libevmasm/RuleList.h @@ -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, |