Add ASSERT_UNREACHABLE and environment opcode semantics #24
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Implement semantics for many Venom IR opcodes that compile to EVM: Assertions: - ASSERT: revert if condition is zero - ASSERT_UNREACHABLE: halt if condition is non-zero Environment context (new state fields): - call_context: caller, address, callvalue, calldata, gas - tx_context: origin, gasprice, chainid - block_context: coinbase, timestamp, number, prevrandao, gaslimit, basefee, blobbasefee, blockhash Environment opcodes: - CALLER, ADDRESS, CALLVALUE, GAS - ORIGIN, GASPRICE, CHAINID - COINBASE, TIMESTAMP, NUMBER, PREVRANDAO, GASLIMIT, BASEFEE, BLOBBASEFEE, BLOCKHASH - BALANCE, SELFBALANCE Calldata/returndata: - CALLDATASIZE, CALLDATALOAD, CALLDATACOPY - RETURNDATASIZE, RETURNDATACOPY - MSIZE Hashing (using Keccak from HOL4): - SHA3: Keccak256 on memory region - SHA3_64: Keccak256 on two words (Vyper optimization) External calls (CALL, STATICCALL, DELEGATECALL) are left unimplemented for now - they error out. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <[email protected]>
xrchz
reviewed
Dec 26, 2025
venom/venomSemScript.sml
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| let dest = w2n destOffset in | ||
| let mem = s.vs_memory in | ||
| let needed = (dest + size) - LENGTH mem in | ||
| let expanded = if needed > 0 then mem ++ REPLICATE needed 0w else mem in |
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we do have expand_memory helpers in verifereum that could possibly be used here
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I think we should probably just add comments everywhere that verifereum functionality could be used and then do a pass over verifereum to extract helper functions for each opcode, then revisit this code after that pass
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I don't think there are that many other opportunities. Maybe if verifereum were refactored too, but I don't want this to bleed into that for now...
xrchz
approved these changes
Dec 26, 2025
Extract the common pattern of expanding memory then writing bytes into a reusable helper function write_memory_with_expansion. Refactor CALLDATACOPY and RETURNDATACOPY to use this helper, reducing code duplication. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <[email protected]>
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Summary
Opcodes Implemented
Assertions:
Environment:
Calldata/Returndata:
Hashing:
Not Implemented
External calls (CALL, STATICCALL, DELEGATECALL) are left as "unimplemented opcode" errors for now.
Test plan
Holmakebuilds successfully🤖 Generated with Claude Code