Section 07: Salsa Integration & Transition

Status: Not Started Goal: Make the bytecode VM actually usable in the Ori compiler. Sections 04-05 build the VM in isolation; this section wires it into the real runtime entry points so ori run and the interpreter-backed ori test path can use it, while ori check and type-driven const-eval continue to rely on the preserved tree-walker where appropriate. Without this section, the VM is a standalone module that can’t run programs through the compiler’s real execution surfaces.

Context: Ori has two runtime-facing interpreter entry points today, and both must be integrated:

ori run uses evaluated() / run_evaluation() in compiler/oric/src/query/mod.rs
ori test uses TestRunner::run_file_with_interner() in compiler/oric/src/test/runner/mod.rs, which builds an Evaluator directly and calls load_module(...)
Import/module wiring lives in Evaluator::load_module() (compiler/oric/src/eval/evaluator/module_loading.rs), not only at the top-level query boundary

The bytecode VM must plug into this same pipeline. The tree-walker cannot simply be deleted because:

ConstEval mode is used by the type checker for compile-time evaluation of $name constants and #cfg conditions. It needs budget limiting, no I/O, and deterministic behavior. The VM can serve this role, but only after the VM supports budget tracking.
TestRun mode is part of the evaluator contract for test execution. The VM must preserve the runtime semantics needed by the test runner, but the runner itself still owns test enumeration, filtering, and pass/fail bookkeeping.
PatternExecutor trait — Interpreter implements PatternExecutor from ori_patterns, used for pattern system integration. The VM must either implement this trait or the pattern system must be updated.

Reference implementations:

Rust const fn evaluation uses MIR interpreter (separate from codegen). Tree-walker is the const-eval engine; LLVM is the runtime engine.
Zig comptime uses the same Sema interpreter for both compile-time and runtime, with a mode flag.
CPython caches compiled .pyc bytecode; the compile() step is separate from exec().

Depends on: Section 05 (working bytecode VM).

07.1 Salsa Query Integration

File(s): compiler/oric/src/query/mod.rs, compiler/oric/src/test/runner/mod.rs, compiler/oric/src/eval/evaluator/module_loading.rs, compiler/ori_eval/src/lib.rs

Wire the bytecode VM into the real execution entry points so programs can execute through the full runtime pipeline.

Current pipeline (query/mod.rs:392-448):

evaluated() → parsed() → typed() → canonicalize_cached() → Evaluator::builder().build() → load + run

Target runtime shape (with VM):

ori run:
  evaluated() / run_evaluation() → canonicalize_cached() →
    if VM_ENABLED: compile chunk → VM::execute() → ModuleEvalResult
    else: Evaluator(tree-walker) → ModuleEvalResult

ori test:
  TestRunner → Evaluator::load_module(...) / backend dispatch →
    if VM backend enabled: compile chunk(s) + execute test body through VM
    else: existing tree-walker path

07.2 Const-Eval and Test-Mode Preservation

File(s): compiler/ori_eval/src/eval_mode/mod.rs, compiler/ori_eval/src/bytecode/vm.rs

The tree-walker serves three EvalModes. The VM must either replace all three or the tree-walker must be preserved for modes the VM cannot handle.

Current modes (eval_mode/mod.rs):

07.3 Feature Flag and Switchover

File(s): compiler/oric/src/query/mod.rs, compiler/oric/src/test/runner/mod.rs, compiler/oric/src/commands/run/mod.rs, compiler/oric/src/commands/test.rs, compiler/oric/src/main.rs

Provide a way to gradually switch from tree-walker to VM without a big-bang cutover.

07.4 Tree-Walker Retirement Strategy

File(s): compiler/ori_eval/src/interpreter/mod.rs, compiler/ori_eval/src/lib.rs

Define what happens to the tree-walker after the VM is the default.

07.R Third Party Review Findings

None.

07.N Completion Checklist

Exit Criteria: ori run --vm can execute any Ori program through the full Salsa pipeline. ori test --vm passes all 5,800+ spec tests. ConstEval mode unaffected. A feature flag controls the switchover. The tree-walker is preserved for compile-time evaluation.