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Merge pull request #6256 from ethereum/completeLtGtRules

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Complete the GT/LT rules.
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chriseth 2019-03-13 12:08:34 +01:00 committed by GitHub
commit 4c1a9aa273
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2 changed files with 4 additions and 1 deletions
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1
Changelog.md
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@ -10,6 +10,7 @@ Language Features:
Compiler Features:
* Optimizer: Add rules for ``lt``-comparisons with constants.
* Peephole Optimizer: Remove double ``iszero`` before ``jumpi``.
* SMTChecker: Support enums without typecast.
* SMTChecker: Support one-dimensional arrays.

4
libevmasm/RuleList.h
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@ -146,10 +146,12 @@ std::vector<SimplificationRule<Pattern>> simplificationRuleListPart2(
{{Instruction::SHR, {0, X}}, [=]{ return X; }, false},
{{Instruction::SHL, {X, 0}}, [=]{ return u256(0); }, true},
{{Instruction::SHR, {X, 0}}, [=]{ return u256(0); }, true},
{{Instruction::LT, {X, 0}}, [=]{ return u256(0); }, true},
{{Instruction::GT, {X, 0}}, [=]() -> Pattern { return {Instruction::ISZERO, {{Instruction::ISZERO, {X}}}}; }, false},
{{Instruction::LT, {0, X}}, [=]() -> Pattern { return {Instruction::ISZERO, {{Instruction::ISZERO, {X}}}}; }, false},
{{Instruction::GT, {X, ~u256(0)}}, [=]{ return u256(0); }, true},
{{Instruction::LT, {~u256(0), X}}, [=]{ return u256(0); }, true},
{{Instruction::GT, {0, X}}, [=]{ return u256(0); }, true},
{{Instruction::LT, {X, 0}}, [=]{ return u256(0); }, true},
{{Instruction::AND, {{Instruction::BYTE, {X, Y}}, {u256(0xff)}}}, [=]() -> Pattern { return {Instruction::BYTE, {X, Y}}; }, false},
{{Instruction::BYTE, {X, 31}}, [=]() -> Pattern { return {Instruction::AND, {X, u256(0xff)}}; }, false}
};