SIMD-0266: Efficient Token program

[febo]

Problem

SIMD-0266 proposes to replace the current verion of SPL Token with p-token.

Summary of Changes

This PR includes the following changes:

• Add a migration path for a Loader v2 program to Loader v3 using a similar setup as builtin to Core BPF.
• Add a feature to agave-feature-set and its activation on bank.rs, which uses the migrate_bpf_loader_v2_to_v3 to replace the SPL Token program data.

The feature activation and migration of the account have been tested using a Core BPF migration CLI fork:

Logs from the test validator:

[2025-07-23T17:31:26.974514281Z INFO  solana_runtime::bank] Feature ptokSWRqZz5u2xdqMdstkMKpFurauUpVen7TZXgDpkQ activated at slot 40
[2025-07-23T17:31:26.974570665Z INFO  solana_metrics::metrics] datapoint: replace_spl_token_with_p_token slot=40i

Additionally, it was also tested using a "p-token migration simulator" tool.

Before the upgrade of SPL Token program:

After the feature is activated and the program upgraded:

Note

When the feature is activated and the program is swapped, it stays in DelayVisibility for 1 slot – the first slot of the epoch after the feature activation – which means that any transaction executing SPL Token instructions will fail during that slot.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 98.78472% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.2%. Comparing base (28b8616) to head (45770bc).
⚠️ Report is 1700 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff            @@
##           master    #7125    +/-   ##
========================================
  Coverage    83.2%    83.2%            
========================================
  Files         863      864     +1     
  Lines      374519   375041   +522     
========================================
+ Hits       311611   312144   +533     
+ Misses      62908    62897    -11     

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[buffalojoec]

The v2 target implementation is looking great! I reviewed the migration path, but haven't checked the tests yet since it's still a draft.

[febo]

The v2 target implementation is looking great! I reviewed the migration path, but haven't checked the tests yet since it's still a draft.

I was waiting for CI to pass – all good now! 😊

[joncinque]

Looks good to me, once Joe's last comment is addressed!

[buffalojoec]

Looks good to me, just need a feature-set rebase & CI to pass!

I think maybe, just to be insanely careful, we should also add a test with live transactions and a valid "stub" ELF. I did a few of these over here:

agave/runtime/src/bank/builtin_programs.rs

Line 65 in d30889f

mod tests_core_bpf_migration {

[buffalojoec]

Changes look good on my side, but I'd still love to see a stub test as I mentioned up here.

[buffalojoec]

Looking good, but let's reduce some redundancy.

[buffalojoec]

I think this looks great! Just get @Lichtso's sign off on the cache step. Otherwise g2g from my side.

[joncinque]

Still looks great to me!

fixed!