This EIP tries to fix the problems with Ethereum precompiles and built-in EVM function:

• EIP-2046 changes a STATICCALL cost to precompile and it may be necessary to adjust costs of some precompiles that have taken old large cost (700 gas) into account
• Some precompiles are overpriced and their pricing formulas to not reflect the structure of underlying function
• Keccak256 built-in function in EVM has pricing that does not reflect underlying hash function structure

Costs of many precompiles and built-in functions are invalid at the current state of the clients. This EIP contains a list of changes to the pricing formulas to better reflect underlying computations' structure.

Motivation is simple: make pricing formulas accurately reflect resources (CPU time) requires to actually perform the called computations.

This EIP proposes the following changes:

• Small running time to perform gas estimation for precompile call is absorbed into the precompile cost itself
• Precompiles are repricied as:
  • SHA256 precompile (address 0x02) was priced as 60 gas plus 12 gas per 32 bytes of input. Now it should be priced as 12 + ((len(input) + 8)/64 + 1) * 5
  • RIPEMD precompile (address 0x03) was priced as 600 gas plus 120 gas per 32 bytes of input. Now it should be priced as 16 + ((len(input) + 8)/64 + 1) * 6
  • BNADD precompile (address 0x06) should be repriced from 150 gas to 350 gas
  • BNMUL precompile (address 0x07) should be repriced from 6000 gas to 6300 gas
• Keccak256 built-in function was priced as 30 gas plus 6 gas per 32 bytes of the input. Now it should be priced as 16 + (len(input)/136 + 1)*13
  • If Geth implementation of Keccak256 is reworked than formula can be changed further to 16 + (len(input)/136 + 1)*2
• Client implementations of gas metering function SHOULD be implemented with efficiency in mind, e.g. use uint64 type instead of uint256 that is sufficient for all reasonable prices taking into the account gas limits in the block

This EIP requires that MODEXP repricing is implemented to also accurately reflect that there is implicit compensation for an old STATICCALL cost (pre-2046).

Cost of functions being executed must accurately reflect real CPU time spent on computations, so benchmarking was performed for current precompiles and Keccak256 function to measure running time versus input parameters.

Precompile repricings has happened in a past and can be considered standard procedure. Gas costs of many contracts is expected to reduce that may break re-entrancy protection measures based on fixed gas costs. In any case, such protection should have never been considered good and final.

There are no explicit test cases.

Reference material with raw data can be found here.

As descriped in backward compatibility section in some cases reduction of cost may allow e.g. re-entrancy that was not expected before, but we think that re-entrancy protection based on fixed gas costs is anyway flawed design decision.

Copyright and related rights waived via CC0.