88 lines
2.4 KiB
Markdown
88 lines
2.4 KiB
Markdown
|
# Phase 70-A: Relay Runtime Guard
|
||
|
|
|
||
|
|
**Status**: Implementation Phase
|
||
|
|
**Date**: 2025-12-13
|
||
|
|
|
||
|
|
---
|
||
|
|
|
||
|
|
## Overview
|
||
|
|
|
||
|
|
Phase 66 enabled multihop relay acceptance at the analysis/plan layer (`plan_to_p2_inputs_with_relay` / `plan_to_p3_inputs_with_relay`). However, the **runtime lowering path** (actual MIR generation) does not yet support multihop execution.
|
||
|
|
|
||
|
|
This phase establishes a **Fail-Fast boundary** with a standardized error tag to clearly indicate "analysis OK, runtime not yet supported."
|
||
|
|
|
||
|
|
---
|
||
|
|
|
||
|
|
## Current State
|
||
|
|
|
||
|
|
| Layer | Multihop Support | Status |
|
||
|
|
|-------|-----------------|--------|
|
||
|
|
| `plan_to_p2_inputs_with_relay` | ✅ Accepts | Phase 66 complete |
|
||
|
|
| `plan_to_p3_inputs_with_relay` | ✅ Accepts | Phase 66 complete |
|
||
|
|
| **P3 runtime lowering** | ❌ Rejects | Phase 70-A guard |
|
||
|
|
| P2 runtime lowering | ❌ Not integrated | Future |
|
||
|
|
|
||
|
|
---
|
||
|
|
|
||
|
|
## Fail-Fast Tag
|
||
|
|
|
||
|
|
**Standard Tag**: `[ownership/relay:runtime_unsupported]`
|
||
|
|
|
||
|
|
When multihop relay (`relay_path.len() > 1`) is detected at runtime:
|
||
|
|
|
||
|
|
```
|
||
|
|
[ownership/relay:runtime_unsupported] Multihop relay not executable yet: var='sum', owner=ScopeId(0), relay_path=[ScopeId(2), ScopeId(1)]
|
||
|
|
```
|
||
|
|
|
||
|
|
**Diagnostic fields**:
|
||
|
|
- Variable name being relayed
|
||
|
|
- Owner scope ID
|
||
|
|
- Relay path (inner → outer)
|
||
|
|
- Relay path length
|
||
|
|
|
||
|
|
---
|
||
|
|
|
||
|
|
## Implementation Location
|
||
|
|
|
||
|
|
**File**: `src/mir/builder/control_flow/joinir/patterns/pattern3_with_if_phi.rs`
|
||
|
|
|
||
|
|
**Function**: `check_ownership_plan_consistency()`
|
||
|
|
|
||
|
|
**Behavior**: On `relay_path.len() > 1`, return `Err` with standardized tag.
|
||
|
|
|
||
|
|
---
|
||
|
|
|
||
|
|
## Release Conditions (Phase 70-B+)
|
||
|
|
|
||
|
|
The `[ownership/relay:runtime_unsupported]` guard can be removed when:
|
||
|
|
|
||
|
|
1. **Exit PHI merge** implemented at owner scope
|
||
|
|
2. **Boundary carrier propagation** for intermediate scopes
|
||
|
|
3. **Integration tests** passing for 3+ layer nested loops
|
||
|
|
4. **No regression** in existing Pattern3 tests
|
||
|
|
|
||
|
|
---
|
||
|
|
|
||
|
|
## Test Coverage
|
||
|
|
|
||
|
|
**Test**: `test_phase70a_multihop_relay_runtime_unsupported_tag`
|
||
|
|
|
||
|
|
Verifies:
|
||
|
|
- 3-layer nested loop AST (L1 owns `sum`, L3 writes `sum`)
|
||
|
|
- Runtime path returns `Err`
|
||
|
|
- Error message contains `[ownership/relay:runtime_unsupported]`
|
||
|
|
|
||
|
|
---
|
||
|
|
|
||
|
|
## Related Documents
|
||
|
|
|
||
|
|
- [Phase 65: Multihop Design](phase65-ownership-relay-multihop-design.md)
|
||
|
|
- [Phase 66: Multihop Implementation](phase65-ownership-relay-multihop-design.md#phase-66-implementation-status)
|
||
|
|
- [Phase 56: Ownership-Relay Architecture](phase56-ownership-relay-design.md)
|
||
|
|
|
||
|
|
---
|
||
|
|
|
||
|
|
## Changelog
|
||
|
|
|
||
|
|
- **2025-12-13**: Phase 70-A created - Fail-Fast tag standardization
|