88 lines
3.7 KiB
Markdown
88 lines
3.7 KiB
Markdown
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---
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eip: 1109
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title: PRECOMPILEDCALL opcode (Remove CALL costs for precompiled contracts)
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author: Jordi Baylina (@jbaylina)
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discussions-to: https://ethereum-magicians.org/t/eip-1109-remove-call-costs-for-precompiled-contracts/447
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status: Stagnant
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type: Standards Track
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category: Core
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created: 2018-05-22
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---
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## Simple Summary
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This EIP creates a specific opcode named `PRECOMPILEDCALL` to call Precompiled contracts without the costs of a normal `CALL`.
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## Abstract
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This EIP tries to resolve the problem of high gas consumption when calling precompiled contracts with a small gas cost. Using this opcode for calling precompiled contracts allows to define precompiled contracts whose effective cost it is less than 700.
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## Motivation
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Each precompiled contract has an already defined cost for calling it. It does not make sense to add the implicit extra gas cost of the CALL opcode.
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As an example, SHA256 precompiled contract costs 60 and ECADD costs 500 (proposed to costs only 50 in [EIP-1108](./eip-1108.md) . When a precompiled contract is called, 700 gas is consumed just for the CALL opcode besides the costs of the precompiled contract.
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This makes no sense, and right now it's impossible to define a precompiled contract whose effective cost for using it, is less than 700.
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## Specification
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If `block.number >= XXXXX`, define a new opcode named `PRECOMPILEDCALL` with code value `0xfb`.
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The gas cost of the OPCODE is 2 (Gbase) plus the Specific gas cost defined for each specific precompiled smart contract.
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The OPCODE takes 5 words from the stack and returns 1 word to the stack.
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The input stack values are:
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mu_s[0] = The address of the precompiled smart contract that is called.
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mu_s[1] = Pointer to memory for the input parameters.
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mu_s[2] = Length of the input parameters in bytes.
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mu_s[3] = Pointer to memory where the output is stored
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mu_s[4] = Length of the output buffer.
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The return will be 1 in case of success call and 0 in any of the next cases:
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1.- mu_s[0] is an address of an undefined precompiled smart contract.
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2.- The precompiled smart contract fails (as defined on each smart contract). Invalid input parameters for example.
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Precompiled smart contracs, does not execute opcodes, so there is no need to pass a gas parameter as a normal `CALL` (`0xf1`). If the available gas is less that 2 plus the required gas required for the specific precompiled smart cotract, the context just STOPS executing with an "Out of Gas" error.
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There is no stack check for this call.
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The normal `CALL`s to the precompiled smart contracts continue to work with the exact same behavior.
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A `PRECOMPILEDCALL` to a regular address or regular smart contract, is considered a call to an "undefined smart contract", so the VM MUST not execute it and the opcode must return 0x0 .
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## Rationale
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There was a first proposal for removing the gast consts for the `CALL`, but it looks that it's easier to implement and test a new opcode just for that.
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The code is just the next opcode available after the `STATICCALL` opcode.
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## Backwards Compatibility
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This EIP is backwards compatible. Smart contracts that call precompiled contracts using this new opcode will cost less from now on.
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Old contracts that call precompiled smart contracts with the `CALL` method, will continue working.
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## Test Cases
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- Normal call to a defined precompiled contract.
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- Call to undefined precompiled contract.
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- Call to a regular contract
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- Call to a regular account
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- Call to 0x0 smart contract (Does not exists).
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- Call with large values for the offste pointers and lengths
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- Call with the exact gas remaining needed to call smart contract.
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- Call with the exact gas remaining minus one needed to call smart contract.
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## Implementation
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Not implemented yet.
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## Copyright
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Copyright and related rights waived via [CC0](../LICENSE.md).
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