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| author | chriseth <c@ethdev.com> | 2017-03-03 23:17:21 +0800 |
|---|---|---|
| committer | chriseth <c@ethdev.com> | 2017-03-03 23:51:37 +0800 |
| commit | ddc4918f3602744544b42da7507fc473e522b61c (patch) | |
| tree | aff58fac5cb7a9c51c5d7419e91f3e66400682b5 | |
| parent | 05dac999223220fdb54c0d28781b3ef1d621061d (diff) | |
| download | dexon-solidity-ddc4918f3602744544b42da7507fc473e522b61c.tar.gz dexon-solidity-ddc4918f3602744544b42da7507fc473e522b61c.tar.zst dexon-solidity-ddc4918f3602744544b42da7507fc473e522b61c.zip | |
Add upper bound for computing constants.
| -rw-r--r-- | libevmasm/ConstantOptimiser.cpp | 4 | ||||
| -rw-r--r-- | libevmasm/ConstantOptimiser.h | 2 |
2 files changed, 5 insertions, 1 deletions
diff --git a/libevmasm/ConstantOptimiser.cpp b/libevmasm/ConstantOptimiser.cpp index 86244e17..a1dfd21c 100644 --- a/libevmasm/ConstantOptimiser.cpp +++ b/libevmasm/ConstantOptimiser.cpp @@ -194,7 +194,7 @@ AssemblyItems ComputeMethod::findRepresentation(u256 const& _value) // Is not always better, try literal and decomposition method. AssemblyItems routine{u256(_value)}; bigint bestGas = gasNeeded(routine); - for (unsigned bits = 255; bits > 8; --bits) + for (unsigned bits = 255; bits > 8 && m_maxSteps > 0; --bits) { unsigned gapDetector = unsigned(_value >> (bits - 8)) & 0x1ff; if (gapDetector != 0xff && gapDetector != 0x100) @@ -219,6 +219,8 @@ AssemblyItems ComputeMethod::findRepresentation(u256 const& _value) else if (lowerPart < 0) newRoutine.push_back(Instruction::SUB); + if (m_maxSteps > 0) + m_maxSteps--; bigint newGas = gasNeeded(newRoutine); if (newGas < bestGas) { diff --git a/libevmasm/ConstantOptimiser.h b/libevmasm/ConstantOptimiser.h index dfa2fbf8..4f12c49f 100644 --- a/libevmasm/ConstantOptimiser.h +++ b/libevmasm/ConstantOptimiser.h @@ -143,6 +143,8 @@ protected: AssemblyItems findRepresentation(u256 const& _value); bigint gasNeeded(AssemblyItems const& _routine); + /// Counter for the complexity of optimization, will stop when it reaches zero. + size_t m_maxSteps = 10000; AssemblyItems m_routine; }; |