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Update EIP-3670: Align with EOF Megaspec and other EIPs
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pdobacz authored and GAEAlimited committed Jun 19, 2024
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30 changes: 14 additions & 16 deletions EIPS/eip-3670.md
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Expand Up @@ -38,12 +38,10 @@ The EOF1 format provides following forward compatibility properties:

## Specification

*Remark:* We rely on the notation of *initcode*, *code* and *creation* as defined by [EIP-3540](./eip-3540.md).

This feature is introduced on the same block EIP-3540 is enabled, therefore every EOF1-compatible bytecode MUST be validated according to these rules.

1. Previously deprecated instructions `CALLCODE` (0xf2) and `SELFDESTRUCT` (0xff) are invalid and their opcodes are undefined.
2. At contract creation time *instructions validation* is performed on both *initcode* and *code*. The code is invalid if any of the checks below fails. For each instruction:
1. Previously deprecated instructions `CALLCODE` (0xf2) and `SELFDESTRUCT` (0xff), as well as instructions deprecated in EIP-3540, are invalid and their opcodes are undefined. (**NOTE** there are more instructions deprecated and rejected in EOF, as specced out by separate EIPs)
2. At contract creation time *code validation* is performed on each code section of the EOF container. The code is invalid if any of the checks below fails. For each instruction:
1. Check if the opcode is defined. The `INVALID` (0xfe) is considered defined.
2. Check if all instructions' immediate bytes are present in the code (code does not end in the middle of instruction).

Expand All @@ -65,45 +63,45 @@ This change poses no risk to backwards compatibility, as it is introduced at the

### Contract creation

Each case should be tested for creation transaction, `CREATE` and `CREATE2`.

- Invalid initcode
- Valid initcode returning invalid code
- Valid initcode returning valid code
Each case should be tested by submitting an EOF container to EOF contract creation (as specced out in a separate EIP). Each case should be tested with code placed in code sections at different indices.

### Valid codes

- EOF code containing `INVALID`
- EOF code with data section containing bytes that are undefined instructions
- Legacy code containing undefined instruction
- Legacy code ending with incomplete PUSH instruction

### Invalid codes

- EOF code containing undefined instruction
- EOF code containing an undefined instruction
- EOF code ending with incomplete `PUSH` instruction
- This can include `PUSH` instruction unreachable by execution, e.g. after `STOP`

## Reference Implementation

```python
# The ranges below are as specified in the Yellow Paper.
# The ranges below are as specified by Execution Specs for Shanghai.
# Note: range(s, e) excludes e, hence the +1
valid_opcodes = [
shanghai_opcodes = [
*range(0x00, 0x0b + 1),
*range(0x10, 0x1d + 1),
0x20,
*range(0x30, 0x3f + 1),
*range(0x40, 0x48 + 1),
*range(0x50, 0x5b + 1),
0x5f,
*range(0x60, 0x6f + 1),
*range(0x70, 0x7f + 1),
*range(0x80, 0x8f + 1),
*range(0x90, 0x9f + 1),
*range(0xa0, 0xa4 + 1),
# Note: 0xfe is considered assigned.
0xf0, 0xf1, 0xf3, 0xf4, 0xf5, 0xfa, 0xfd, 0xfe
0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xfa, 0xfd, 0xfe, 0xff
]

# Drop the opcodes deprecated and rejected in here and in EIP-3540
rejected_in_eof = [
0x38, 0x39, 0x3b, 0x3c, 0x3f, 0x5a, 0xf1, 0xf2, 0xf4, 0xfa, 0xff
]
valid_opcodes = [op for op in shanghai_opcodes not in rejected_in_eof]

immediate_sizes = 256 * [0]
immediate_sizes[0x60:0x7f + 1] = range(1, 32 + 1) # PUSH1..PUSH32
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