feat: add LOOKUP_DELEGATED_ADDRESS precompile wrapper by pali101 · Pull Request #9 · filecoin-project/fvm-solidity

pali101 · 2026-03-01T17:17:51Z

Summary

Implements the LOOKUP_DELEGATED_ADDRESS precompile wrapper (0xfe...02) to retrieve an actor's delegated address (f4) and extract the Ethereum-style address using optimized inline assembly.

The primary API returns address for ergonomic use in Solidity while preserving raw bytes helpers for applications that require the f4 encoding.

Addresses all reviewer feedback from the initial submission (#6).

Key Changes

src/FVMActor.sol
- Added tryLookupDelegatedAddress(uint64) → (bool, address): returns empty and exists=false if actor has no delegated address
- Added lookupDelegatedAddress(uint64) → address: strict variant, reverts with DelegatedAddressNotFound(actorId) if no delegated address exists
- Added tryLookupDelegatedAddressBytes(uint64) → (bool, bytes): returns empty and exists=false if actor has no delegated address; defaults to zero slot (0x60) to safely represent empty bytes without allocation
- Added lookupDelegatedAddressBytes(uint64) → bytes: strict raw-bytes variant
src/FVMAddress.sol
- Added toEthAddress(bytes) → address: validates f410 format (length 22, prefix 0x040a) and extracts the last 20 bytes as an Ethereum address
- Added InvalidDelegatedAddress error
src/mocks/FVMActor.sol
- Added delegatedAddressMocks mapping to support LOOKUP_DELEGATED_ADDRESS in the unified fallback
- Added mockLookupDelegatedAddress(uint64, bytes) and mockLookupDelegatedAddress(uint64, address) overloads
- Fallback routes on msg.data.length == 32 to distinguish lookup from resolve calls
src/mocks/MockFVMTest.sol
- Etches and copies storage for LOOKUP_DELEGATED_ADDRESS alongside RESOLVE_ADDRESS
src/Demo.sol
- Exposed tryLookupDelegatedAddress, lookupDelegatedAddress, tryLookupDelegatedAddressBytes, lookupDelegatedAddressBytes, toEthAddress
- Deployed to Calibration: 0x480129258b6A21B817DdEf4A261D230a4d69677A

Reviewer Notes

FVMLookupDelegatedAddress merged into FVMActor per feedback
toEthAddress moved to FVMAddress per feedback
Precompile revert data propagated directly via returndatacopy + revert(0, returnSize), consistent with feat: add RESOLVE_ADDRESS precompile wrapper #5

Update (after review feedback)

Based on reviewer feedback, the delegated address API has been updated to return address by default since delegated addresses are native to the FEVM.

The raw bytes helpers are still available for callers that need the f4/f410 encoding.

Updated API:

tryLookupDelegatedAddress(uint64) → (bool, address)
lookupDelegatedAddress(uint64) → address
tryLookupDelegatedAddressBytes(uint64) → (bool, bytes)
lookupDelegatedAddressBytes(uint64) → bytes

Closes #2

src/mocks/FVMActor.sol

src/FVMAddress.sol

wjmelements · 2026-03-10T02:41:14Z

I think it could be more natural to return address for delegated address since a delegated address is native to the FEVM. However, we should keep the bytes method in case somebody needs to format it that way, so they aren't forced to decode and re-encode it.

…Address

- Replaced `msg.data.length` checks with `address(this)` routing to prevent accidental payload collisions.

…ompile mocks - introduce FVMResolveAddress and FVMDelegatedAddress mock contracts - update MockFVMTest to etch both precompile mocks independently - update tests to use RESOLVE_ADDRESS_PRECOMPILE and LOOKUP_DELEGATED_ADDRESS_PRECOMPILE - remove legacy shared FVMActor mock

…es lookup

…structions

src/FVMActor.sol

README.md

wjmelements · 2026-03-17T20:59:29Z

This is very close to merging. Can you link a deployed Demo contract with your next push?

test/Address.t.sol

wjmelements · 2026-03-17T23:33:31Z

test/Address.t.sol

+        bytes memory tooShort = abi.encodePacked(uint8(0x04), uint8(0x0a), bytes19(0));
+
+        vm.expectRevert(FVMAddress.InvalidDelegatedAddress.selector);
+        this._toEthAddress(tooShort);


I don't think you have to explicitly this.

We need to keep this. Foundry's vm.expectRevert() only catches reverts on external calls by default. Without it, it becomes an internal call, which crashes the test and fails with: [FAIL: call didn't revert at a lower depth than cheatcode call depth]

That said, Foundry recently added a config to allow testing internal reverts. I can add /// forge-config: default.allow_internal_expect_revert = true above these tests and drop the this. if you prefer that pattern! Let me know what you think is cleaner.

… leak

- Combined BigBrain code blocks in README.md for clarity. - Moved _toEthAddress under the correct test banner in Address.t.sol.

pali101 · 2026-03-20T08:44:50Z

Here is the deployed Demo contract on the Calibration testnet: 0x09f149b6AeCFCeF271fA2E84b01205373c84c16D

I also ran a quick profiling trick: by using cast send instead of cast call on the view function, I forced a transaction to get the exact WASM gas trace on the block explorer. This comparison is before and after the returndatasize() and input overwrite optimizations.

Before: 3205778 (txn hash: 0x13de8f573707c7845b7764c72a3f816a36781e47a5323beef967a4bb811b3c6a)
After: 2702216 (txn hash: 0x3fe4999b1037c08b3801f1ade2c705a941a3e80da2b3bc3dbb7d9cf494ad9e9b)

Saving: 503562 gas

pali101 mentioned this pull request Mar 1, 2026

feat: add LOOKUP_DELEGATED_ADDRESS precompile wrapper #6

Closed

wjmelements reviewed Mar 2, 2026

View reviewed changes

src/mocks/FVMActor.sol Outdated Show resolved Hide resolved

wjmelements reviewed Mar 7, 2026

View reviewed changes

src/FVMAddress.sol Outdated Show resolved Hide resolved

pali101 added 12 commits March 15, 2026 11:46

feat(FVMActor): add tryLookupDelegatedAddress and lookupDelegatedAddress

a3c25ce

feat(FVMAddress): add toEthAddress for f410 delegated address extraction

c6a4625

feat(mocks): add delegated address mock storage and lookup overloads

63eda02

test(mocks): etch and copyStorage LOOKUP_DELEGATED_ADDRESS precompile

3a4a558

test(Actor): add delegated address and lifecycle tests

4443082

test(FVMAddress): add toEthAddress, f0, f4, f410 unit and fuzz tests

497269a

demo: expose tryLookupDelegatedAddress, lookupDelegatedAddress, toEth…

618102d

…Address

refactor(mock): route FVMActor fallback via precompile address

3b9d0f0

- Replaced `msg.data.length` checks with `address(this)` routing to prevent accidental payload collisions.

perf(FVMAddress): simplify delegated address prefix check using xor

93d64a6

feat(actor): return delegated EVM address by default and preserve byt…

3e89921

…es lookup

docs: add LookupDelegatedAddress usage, tests, and demo deployment in…

7ff91ad

…structions

pali101 force-pushed the feat/lookup-delegated-address-v2 branch from e85b4bf to 7ff91ad Compare March 15, 2026 06:16

pali101 mentioned this pull request Mar 15, 2026

docs: add LookupDelegatedAddress usage and deploy-demo script #11

Closed