1. STATE VARIABLES SHOULD BE CACHED IN STACK VARIABLES RATHER THAN RE-READING THEM FROM STORAGE
The instances below point to the second access of a state variable within a function. Caching will replace each Gwarmaccess (100 gas) with a much cheaper stack read.
2. <ARRAY>.LENGTH SHOULD NOT BE LOOKED UP IN EVERY LOOP OF A FOR-LOOP
Even memory arrays incur the overhead of bit tests and bit shifts to calculate the array length. Storage array length checks incur an extra Gwarmaccess (100 gas) PER-LOOP.
1. STATE VARIABLES SHOULD BE CACHED IN STACK VARIABLES RATHER THAN RE-READING THEM FROM STORAGE
The instances below point to the second access of a state variable within a function. Caching will replace each Gwarmaccess (100 gas) with a much cheaper stack read.
PuttyV2.sol::fillOrder():Cache
wethin following lines:PuttyV2.sol::exercise():Cache
wethin following lines:PuttyV2.sol::withdraw():Cache
feein following lines:2.
<ARRAY>.LENGTHSHOULD NOT BE LOOKED UP IN EVERY LOOP OF A FOR-LOOPEven memory arrays incur the overhead of bit tests and bit shifts to calculate the array length. Storage array length checks incur an extra Gwarmaccess (100 gas) PER-LOOP.
Cache
<array>.lengthin following lines:3. use
++iinstead ofi++4. IT COSTS MORE GAS TO INITIALIZE VARIABLES TO ZERO THAN TO LET THE DEFAULT OF ZERO BE APPLIED
no need to assign 0 to unsigned variables:
5. EXPRESSIONS FOR CONSTANT VALUES SUCH AS A CALL TO KECCAK256(), SHOULD USE IMMUTABLE RATHER THAN CONSTANT
6. USE CUSTOM ERRORS RATHER THAN REVERT()/REQUIRE() STRINGS TO SAVE DEPLOYMENT GAS
https://blog.soliditylang.org/2021/04/21/custom-errors/