Elamur Groupantsmlab-vm-compiler
The groupant beside mlab/src/vm.rs in the Mova repository: what the code computes, what it never does, how to go back from its outputs, its invariants, cost and checks.
Facts
Implementation material. A Mova code model describes this code at one source revision: partial models, finite checks and their stated scope. It is not a reviewed general exposition, and its labels are shown as written, never raised.
Components
| component | label | where |
|---|---|---|
| approximant | partial | approximant |
| ast | partial | ../syntax.json |
| cost | symbolic source derived | invariant |
| descriptant | present | descriptant |
| invariant | partial | invariant |
| tests | executed bounded checks | tests |
Obernants
The typed relations around the forward model: the behaviour complement (what the code never does), the reverse reconstruction (every input compatible with an output) and specialised views.
| id | type | label | where |
|---|---|---|---|
behavior_complement | behavior_complement | partial source derived model | behavior_complement |
reverse_reconstruction | reverse_reconstruction | partial source derived model | reverse_reconstruction |
fallback_selection | fallback_selection | partial source derived model | fallback_selection |
order_guard | order_guard | partial source derived model | order_guard |
range_compilation | range_compilation | partial source derived model | range_compilation |
register_budget | register_budget | partial source derived model | register_budget |
Model text
descriptant
mlab-vm-compiler
AST classification, register assignment, bytecode emission and jump patching.
Epoch 2026-10-31
Half-open source bytes [10660,45698); bound by parent source hash and scoped byte hash. Model covers only this fragment; parent composition explains joins.
approximant
Scoped forward relation
Collect assigned variables/params/outputs, classify statements, emit native ops or Fb; loops patch exits/continues; sorted functions determine call indices.
Domain and gap
Source-generated states within resource limits. Categorical relation has no executable percent surrogate.
invariant
Scoped invariant
Try/switch/commands and frame-sensitive expressions become Fallback.
Cost
AST visits and emitted code/tables plus linear string dedup and sorted function names. Nested temporary register demand bounded only by assertion; usize-to-u16/u32/u8 casts need admitted bounds.
models
Scoped typed relations
behavior_complement
Try/switch/commands exclude native statement compilation. Right operands with possible effects exclude direct reuse of left variable registers; unsupported expressions remain tree fallback.
reverse_reconstruction
Bytecode admits multiple ASTs: parenthesization and equivalent constant forms may be lost; fallback retains original Stmt and its sync list.
fallback_selection
Try/switch/commands and frame-sensitive expressions become Fallback.
order_guard
left operand direct register reuse is allowed only if right expression is simple.
range_compilation
For range emits ForRange/ForNext, other iterables ForGen; empty handling is runtime.
register_budget
tmp asserts top<NO; fixed vars and u8 index casts lack a full overflow guarantee.
tests
Evidence scope
Parent selected tests: wave30_bounded_state_and_fallback, wave30_parse_runtime_and_output_state, wave30_synthetic_gate_fail_fast, vm_workspace_is_visible_after_run. This fragment shares parent syntax and finite checks; no separate test count or complete fragment coverage claim. Assertion-control association and unexecuted paths are in parent tests.md and source-test-map.json.
This page in Markdown → https://md.groupants.elamur.ai/free/en/mova/mlab/src/vm.rs.groupant/compiler.groupant/