# Mega EOF Scoping
These are just the opinon of @shemnon and not binding on any other contributors.

## Tier list

### Tier 1: Removing items from Legacy EVM

#### Opcodes Removed

##### Stuff we need to get rid of (no replacement or replacements already exist)
- `SELFDESTRUCT`
- `CALLCODE`

##### Code Introspection:
- `CODSIZE`
- `CODECOPY`
- `EXTCODESIZE`
- `EXTCODECOPY`
- `EXTCODEHASH`
- `CREATE`
- `CREATE2`

##### Gas Introspection:
- `GAS`
- `CALL`
- `DELEGATECALL`
- `STATICCALL`

##### Remove Dynamic Jumps:
- `JUMP`
- `JUMPI`
- `PC`

### Tier 2: Essential Additions

#### These cannot be added without a breaking version change
- Container format
- Static code validation
- Static stack analysis and code section type data
- Code sections for subroutines

#### Without the following, EOF is unsuitable for any use

##### Opcodes enabling essential additions
- `CALLF`
- `JUMPF`
- `RETF`

##### Static jumps: JUMP series replacements
- `RJUMP`
- `RJUMPI`

##### Calling other contracts: CALL series replacement
- `EXTCALL`
- `EXTDELEGATECALL`
- `EXTSTATICCALL`

### Tier 3: Replacements for features lost by bans

#### Compilers will not support untill these are added

Best if in v1.0, but could be added in 1.1 w/o a major version chainge.

##### Factory Contract: CREATE2 replacement
- Subcontainer section
- `EOFCREATE`
- `RETURNCONTRACT`

##### Data in contract, CODECOPY replacement
- data section
- `DATALOAD`
- `DATALOADN`
- `DATASIZE`
- `DATACOPY`

### Tier 4: Important quality of life

Operations and behaviors not replacing removed fatures, but explicitly asked for by compielr teams.

#### Has to ship in 1.0, otherwise completely missed

##### Opcode changes
- Prepare for Address Space Expansion (don't trim addresses in operations) [EIP-7676](https://github.com/ethereum/EIPs/pull/8385)

#### Can Slip out to 1.1

##### Jumps:
- `RJUMPV`

##### Stack (EIP-663)
- `DUPN`
- `SWAPN`
- `EXCHANGE` (swap, but doesn't require stack item 1)

##### EXTCALL usability
- `RETURNDATALOAD`

### Tier 5: Enabling Future Features

#### Account abstraction

##### Creating contracts from bundled code
- Initcode Transaction
- `TXCREATE`

## Shaghai vs Mega

### What was already in Shanghai
Bans -
- `SELFDESTRUCT`
- `CALLCODE`
- `JUMP`
- `JUMPI`
- `PC`

Container -
- Container format
- static code validation
- static stack analysis and code section type data
- code sections for subroutines

Opcodes
- `CALLF`
- `RETF`
- `RJUMP`
- `RJUMPI`
- `RJUMPV`

### New in Mega-EOF
Bans -
- `CODESIZE`
- `CODECOPY`
- `EXTCODESIZE`
- `EXTCODECOPY`
- `EXTCODEHASH`
- `CREATE`
- `CREATE2`
- `GAS`
- `CALL`
- `DELEGATECALL`
- `STATICCALL`

Container -
- Subcontainer section

Behavior -
- Relaxed stack validation (stack ranges)
- Remove Address Space Trimming (prepare for Address Space Expansion)

Opcodes
- `JUMPF`
- `EXTCALL`
- `EXTDELEGATECALL`
- `EXTSTATICCALL`
- `DATALOAD`
- `DATALOADN`
- `DATASIZE`
- `DATACOPY`
- `EOFCREATE`
- `RETURNCONTRACT`
- `DUPN`
- `SWAPN`
- `EXCHANGE`
- `RETURNDATALOAD`

### New by tier

#### Tier 1
Bans -
- `CODSIZE`
- `CODECOPY`
- `EXTCODESIZE`
- `EXTCODECOPY`
- `EXTCODEHASH`
- `CREATE`
- `CREATE2`
- `GAS`
- `CALL`
- `DELEGATECALL`
- `STATICCALL`

#### Tier 2

Behavior
- Relax Stack Validaiton (ranges and forward references)

Opcodes
- `JUMPF`
- `EXTCALL`
- `EXTDELEGATECALL`
- `EXTSTATICCALL`

#### Tier 3

EOF sections
- Subcontainer section

Opocodes
- `EOFCREATE`
- `RETURNCONTRACT`
- `DATALOAD`
- `DATALOADN`
- `DATASIZE`
- `DATACOPY`

#### Tier 4
Behavior
- Prepare for ASE (change to BALANCE, plus testing)

Opcodes
- `DUPN`
- `SWAPN`
- `EXCHANGE`
- `RETURNDATALOAD`

#### Tier 5

Transaction types
- Initcode Transaction
- Initcode Transaction receipt

Opcodes
- `TXCREATE`