Description:
One can save gas by caching the array length (in stack) and using that set variable in the loop. Replace state variable reads and writes within loops with local variable reads and writes. This is done by assigning state variable values to new local variables, reading and/or writing the local variables in a loop, then after the loop assigning any changed local variables to their equivalent state variables.
NOTES: _updatedAssets Can be catched before the requrie statement since it is also read there.
Recommendation:
Simply do something like so before the for loop: uint length = variable.length. Then add length in place of variable.length in the for loop.
Description:
Contracts most called functions could simply save gas by function ordering via Method ID. Calling a function at runtime will be cheaper if the function is positioned earlier in the order (has a relatively lower Method ID) because 22 gas are added to the cost of a function for every position that came before it. The caller can save on gas if you prioritize most called functions. One could use This tool to help find alternative function names with lower Method IDs while keeping the original name intact.
Recommendation:
Find a lower method ID name for the most called functions for example mostCalled() vs. mostCalled_41q() is cheaper by 44 gas.
Use ++index instead of index++ to increment a loop counter
Description:
You can cut out 10 opcodes in the creation-time EVM bytecode if you declare a constructor payable. Making the constructor payable eliminates the need for an initial check of msg.value == 0 and saves 21 gas on deployment with no security risks.
Description:
In a require, when checking a uint, using != 0 instead of > 0 saves 6 gas. This will jump over or avoid an extra ISZERO opcode. But this only works in requrie and not in other situations hence it is cheaper to use > 0 instead of !=0 with uint values in an if().
Recommendation:
Use != 0 instead of > 0 with uint values but only in require() statements and use > 0 instead of != 0 in other situations.
In
require(), Use!= 0Instead of> 0With Uint ValuesContext:
NAV.sol#L36-L51,NAV.sol#L56-L61,IndexLogic.sol#L31-L92,IndexLogic.sol#L96-L147Description: In a require, when checking a uint, using
!= 0instead of> 0saves 6 gas. This will jump over or avoid an extraISZEROopcode.Recommendation: Use
!= 0instead of> 0with uint values but only inrequire()statements.Catching The Array Length Prior To Loop
Context:
BaseIndex.sol#L75-L81,IndexLogic.sol#L31-L92 (For both loops),IndexLogic.sol#L96-L147 (For loop at L125-L144),ManagedIndex.sol#L27-L39,ManagedIndexReweightingLogic.sol#L28-L105 (For all 3 loops read additonal notes),TopNMarketCapIndex.sol#L37-L65,TopNMarketCapReweightingLogic.sol#L30-L113 (For all 3 loops),TrackedIndex.sol#L25-L54,TrackedIndexReweightingLogic.sol#L28-L80 (For both loops),UniswapV2PathPriceOracle.sol#L32-L44,UniswapV2PathPriceOracle.sol#L47-L59Description: One can save gas by caching the array length (in stack) and using that set variable in the loop. Replace state variable reads and writes within loops with local variable reads and writes. This is done by assigning state variable values to new local variables, reading and/or writing the local variables in a loop, then after the loop assigning any changed local variables to their equivalent state variables. NOTES:
_updatedAssetsCan be catched before the requrie statement since it is also read there.Recommendation: Simply do something like so before the for loop:
uint length = variable.length. Then addlengthin place ofvariable.lengthin the for loop.Function Ordering via Method ID
Context:
All ContractsDescription: Contracts most called functions could simply save gas by function ordering via Method ID. Calling a function at runtime will be cheaper if the function is positioned earlier in the order (has a relatively lower Method ID) because 22 gas are added to the cost of a function for every position that came before it. The caller can save on gas if you prioritize most called functions. One could use
This toolto help find alternative function names with lower Method IDs while keeping the original name intact.Recommendation: Find a lower method ID name for the most called functions for example
mostCalled()vs.mostCalled_41q()is cheaper by 44 gas.Use
++indexinstead ofindex++to increment a loop counterContext:
BaseIndex.sol#L75-L81,UniswapV2PathPriceOracle.sol#L32-L44,UniswapV2PathPriceOracle.sol#L47-L59Description: Due to reduced stack operations, using
++indexsaves 5 gas per iteration.Recommendation: Use
++indexto increment a loop counter.Setting The Constructor To Payable
Context:
BaseIndex.sol#L33-L40,ChainlinkPriceOracle.sol#L46-L57,UniswapV2PathPriceOracle.sol#L23-L29Description: You can cut out 10 opcodes in the creation-time EVM bytecode if you declare a constructor payable. Making the constructor payable eliminates the need for an initial check of
msg.value == 0and saves 21 gas on deployment with no security risks.Recommendation: Set the constructor to payable.
In
if(), Use> 0Instead of!=0With Uint ValuesContext:
NAV.sol#L36-L51,NAV.sol#L77-L88,NAV.sol#L94-L101,IndexLogic.sol#L31-L92Description: In a require, when checking a uint, using
!= 0instead of> 0saves 6 gas. This will jump over or avoid an extraISZEROopcode. But this only works in requrie and not in other situations hence it is cheaper to use> 0instead of!=0with uint values in anif().Recommendation: Use
!= 0instead of> 0with uint values but only inrequire()statements and use> 0instead of!= 0in other situations.uint256Is Cheaper Thanuint8Context:
ChainlinkPriceOracle.sol#L38,ChainlinkPriceOracle.sol#L41,IndexLayout.sol#L27,PhuturePriceOracle.sol#L33,TopNMarketCapIndex.sol#L21Description: The EVM reads in 32 byte words if your data is smaller, further operations are needed to downscale from 256 bits to 8 bit.
Recommendation: use
uint256instead ofuint8.