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jet: populate Bitcoin CMR table - #386

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delta1 wants to merge 11 commits into
BlockstreamResearch:masterfrom
delta1:pr/bitcoin-cmr-cost-tables
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delta1 wants to merge 11 commits into
BlockstreamResearch:masterfrom
delta1:pr/bitcoin-cmr-cost-tables

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@delta1

@delta1 delta1 commented Oct 5, 2026

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Depends on #385 (Bitcoin transaction environment).

Replaces the unimplemented!() stub in Bitcoin::cmr() with the full
match table of 32-byte Commitment Merkle Root (CMR) values, one entry
per jet in the Bitcoin jet set. Each value is taken directly from the
canonical primitiveJetNode.inc in libsimplicity, so the table is a
transcription, not a derivation -- no new CMR computation logic is
introduced here.

Bitcoin::cost() remains a stub; the cost table and the CMR/cost
self-check tests (which assert this table against
primitiveJetNode.inc in code) land in the next PR in the stack.

apoelstra and others added 11 commits October 5, 2026 14:28
Don't actually build bitcoin yet; just refactor build.rs
For dumb "C polymorphism" reasons we have two structures in the C code named
txEnv. We can call the corresponding Rust structures different things, but
we need to access them from the C file env.c, which provides some C wrappers
for FFI stuff.

Since you can't have two different structs with the same name in one compilation
unit, split it into two: add depend/bitcoin_env.c holding the Bitcoin txEnv
wrappers, alongside the existing depend/env.c for Elements.
This is the more correct trait. When we update the Jet trait we will
be forced to pick one, and we will pick Borrow.
Updates to BlockstreamResearch/simplicity#324

This PR does a couple things simultaneously:

* Runs vendor-simplicity.sh and update-jets.sh
* Updates the `Jet` trait to have associated transaction and environment types,
  and for the environment to be paramterized by the transaction type.
* Changes the Core environment from () to CoreEnv::<Infallible>
* Updates some fixed Core CMR/IHR vectors (this update to libsimplicity changes
  the benchmarks for the Core jets and thus changes these vectors)
* Uncomments the commented-out symbols in simplicity-sys/src/c_jets/c_env/bitcoin.rs
* Adds the "build bitcoin" lines to simplicity-sys/build.rs

The update to the `Jet` trait is a bit noisy but ultimately mechanical: everywhere
that we're generic over all J: Jet, we now also have to be generic over all
T: Borrow<J::Transaction>, which leads to some extra line noise especially in
unit tests where we have assert_* helper functions.

The last four points are tiny diffs, thanks to the previous preparatory commits.

The use of CoreEnv::<Infallible> as the core environment type is kinda fun. It
means that it is impossible to execute any code which attempts to access the
transaction in the environment. (No such code exists, since it would be nonsensical,
but now we have some assurance that it won't exist by accident in the future.)

Unfortunately this mixes mechanical and non-mechanical things in one commit. But
the mechanical changes are exclusively in simplicity-sys/depend/ and src/jet/init/
and the non-mechanical changes are exclusively outside of those files, so it
should be possible to review this.
Change the JetEnvironment impl for BitcoinEnv and ElementsEnv to be
generic over T: Borrow<Transaction> instead of fixed to Arc<Transaction>.
Update Policy::satisfy, get_satisfier, execute_successful,
execute_unsuccessful, and serialize test helpers to accept
ElementsEnv<impl Borrow<Transaction>>.

This allows callers to construct environments without Arc overhead (for
example, using a plain reference or owned value), and is required so
that BitcoinEnv::c_jet_env can return a real CTxEnv from a borrowed
transaction.
Now that we've updated the Jet trait to allow the transactions in environments
to be arbitrary T: Borrow<Transaction>, we don't need to use Arc everywhere.
In many cases we can use normal references.
This is a Rust type which can be used, among other things, to construct
the transaction environment needed by C jets.

Also provides accessors for the underlying transaction and input index,
both of which are used (in the Elements version of this struct) in the
policy satisfier.
rust-bitcoin 0.32 removed Witness::taproot_annex. Replace it with an
inline BIP341 annex extraction: the last witness element that begins
with 0x50 is the annex. This matches the Elements c_env helper and the
BIP341 specification.
Replace the unimplemented!() stub in Bitcoin::cmr() with a match table
of 32-byte CMR values. Each entry is derived from the canonical
primitiveJetNode.inc in libsimplicity. The table covers all jets in the
Bitcoin jet set.

The cost() method remains a stub pending a separate commit.
@ivanlele

ivanlele commented Oct 6, 2026

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Was this updated with ./update_jets.sh?

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3 participants