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Fix number representation bug.

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chriseth 2017-04-03 14:40:17 +02:00
parent e2f00c96d5
commit 5c4f3f6d0b
2 changed files with 8 additions and 2 deletions
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1
Changelog.md
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@ -18,6 +18,7 @@ Bugfixes:
and source mappings.
* Gas Estimator: Reflect the most recent fee schedule.
* Type system: Contract inheriting from base with unimplemented constructor should be abstract.
* Optimizer: Number representation bug in the constant optimizer fixed.
### 0.4.10 (2017-03-15)

9
libevmasm/ConstantOptimiser.cpp
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@ -203,8 +203,13 @@ AssemblyItems ComputeMethod::findRepresentation(u256 const& _value)
u256 powerOfTwo = u256(1) << bits;
u256 upperPart = _value >> bits;
bigint lowerPart = _value & (powerOfTwo - 1);
if (abs(powerOfTwo - lowerPart) < lowerPart)
if (powerOfTwo - lowerPart < lowerPart)
{
lowerPart = lowerPart - powerOfTwo; // make it negative
upperPart++;
}
if (upperPart == 0)
continue;
if (abs(lowerPart) >= (powerOfTwo >> 8))
continue;
@ -212,7 +217,7 @@ AssemblyItems ComputeMethod::findRepresentation(u256 const& _value)
if (lowerPart != 0)
newRoutine += findRepresentation(u256(abs(lowerPart)));
newRoutine += AssemblyItems{u256(bits), u256(2), Instruction::EXP};
if (upperPart != 1 && upperPart != 0)
if (upperPart != 1)
newRoutine += findRepresentation(upperPart) + AssemblyItems{Instruction::MUL};
if (lowerPart > 0)
newRoutine += AssemblyItems{Instruction::ADD};