Support previous forks instruction sets

[computerality]

Currently pyevmasm only supports the latest/post-Byzantium fork. Would be good to be able to accurately disassemble old code created before the most recent fork. Could be exposed by specifying which fork or by specifying a block number.

[gitcoinbot]

Issue Status: 1. Open 2. Started 3. Submitted 4. Done

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Issue Status: 1. Open 2. Started 3. Submitted 4. Done

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Work has been started.

These users each claimed they can complete the work by 7 months from now.
Please review their action plans below:

1) cryptomental has been approved to start work.

Hi. I would love to start working on this especially with the upcoming hard fork. I would need a bit guidance with the Pre-Byzantium and Constantinople opcodes reference.

I would like to base on https://github.com/trailofbits/evm-opcodes but this reference does not contain information which opcodes were added after Byzantium and will be after Constantinople.

So far I found a concise list for Constaninople on Reddit but perhaps you could guide me to another one.
https://www.reddit.com/r/ethereum/comments/9dti9u/constantinople_overview/

Implementation will involve adding an optional --fork argument (depending how would you like to name it) to pyevmasm set by default to the current fork. The argument would accept fork name (Pre-Byzantium, Byzantium, Constantinople) or a block number that would be automatically converted to fork name.

The instruction_table would then be selected / patched according to the selected fork.

Please let me know if it makes sense and what is your idea whether to implement instruction_table patching with new/removed opcodes or simply use hard-coded instruction_tables for a given fork. The latter solution may bring a little redundancy but will likely be more readable and less error-prone.

I can start working on this ASAP and deliver PR by Friday.

Learn more on the Gitcoin Issue Details page.

[cryptomental]

Thank you for approving me!

I found Constantinople opcodes in evmlab implementation here https://github.com/ethereum/evmlab/blob/e7cdce79d2a938603fd2074adaca01d96651fdbb/evmlab/tools/statetests/rndval/codesmart.py#L85
I will of course check if the list is complete and start tomorrow morning with the implementation.

[gitcoinbot]

Issue Status: 1. Open 2. Started 3. Submitted 4. Done

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Work for 200.0 DAI (200.0 USD @ $1.0/DAI) has been submitted by:

1. @cryptomental

@mkosowsk please take a look at the submitted work:

• PR by @cryptomental

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[cryptomental]

@computerality , @mkosowsk

pyevmasm is now fork-aware and easily extendable to new forks:

A few highlights:

• contains separate instruction tables for pre-byzantium, byzantium and constantinopole.
• added new optional argument to CLI (--fork, -f) that accepts fork to be used.
• it is possible to select fork by name or by block number.
• introduced default fork selection by introducing DEFAULT_FORK constant
• added 3 new test cases, one per supported fork
• fixed test_ADD_1 test case

All functions and evmasm are fully backwards compatible. If no fork is selected, "byzantium" is chosen by default.

Example usage:

# pre-byzantium
evmasm -t -f 0
evmasm -t -f 3700000
evmasm -t -f 4369999
evmasm -t -f pre-byzantium
# byzantium
evmasm -t
evmasm -t -f 4370000
evmasm -t -f 4370001
evmasm -t -f byzantium
# constantinople
evmasm -t -f 9999999  (block number to be updated after mainnet launch)
evmasm -t -f constantinople

Error handling:

$ evmasm -t -f a
Wrong fork name or block number. Please provide an integer or one of ['pre-byzantium', 'byzantium', 'constantinople'].
$ evmasm -t -f constantinoplee
Wrong fork name or block number. Please provide an integer or one of ['pre-byzantium', 'byzantium', 'constantinople'].
$ evmasm -t -f 1.2
Wrong fork name or block number. Please provide an integer or one of ['pre-byzantium', 'byzantium', 'constantinople'].
$ evmasm -t -f
usage: evmasm [-h] (-a | -d | -t) [-bi] [-bo] [-i [INPUT]] [-o [OUTPUT]]
              [-f FORK]
evmasm: error: argument -f/--fork: expected 1 argument

PR opened: #22

[cryptomental]

Merged to master. @mkosowsk this can be closed as well.