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Document the boost multiprecision shift bug in RuleList

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This commit is contained in:
Alex Beregszaszi 2019-02-22 11:53:05 +00:00
parent 68e1bf47d5
commit a7c2dba681
2 changed files with 8 additions and 2 deletions
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6
libdevcore/CommonData.h
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@ -140,6 +140,12 @@ inline bytes toCompactBigEndian(uint8_t _val, unsigned _min = 0)
return (_min || _val) ? bytes{ _val } : bytes{};
}
/// Workarounds shift left bug in boost <1.65.1.
template <class S> S bigintShiftLeftWorkaround(S const& _a, unsigned _b)
{
return (S)(bigint(_a) << _b);
}
/// Convenience function for conversion of a u256 to hex
inline std::string toHex(u256 val, HexPrefix prefix = HexPrefix::DontAdd)
{

4
libevmasm/RuleList.h
View File

@ -87,12 +87,12 @@ std::vector<SimplificationRule<Pattern>> simplificationRuleListPart1(
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);
return boost::multiprecision::bit_test(B.d(), testBit) ? B.d() | ~mask : B.d() & mask;
}, false},
{{Instruction::SHL, {A, B}}, [=]{
if (A.d() > 255)
return u256(0);
return u256(bigint(B.d()) << unsigned(A.d()));
return bigintShiftLeftWorkaround(B.d(), unsigned(A.d()));
}, false},
{{Instruction::SHR, {A, B}}, [=]{
if (A.d() > 255)