# Phase 193-5: Multi-Carrier Testing & Integration

**Phase**: 193-5
**Status**: Implementation Phase
**Date**: 2025-12-06
**Goal**: Validate ExitBindingBuilder with multi-carrier test cases and integrate into Pattern 3 & 4 lowerers

---

## Overview

Phase 193-5 completes the Phase 193 modularization cycle by:
1. Running existing multi-carrier test case to validate design
2. Integrating ExitBindingBuilder into Pattern 3 & 4 lowerers
3. Removing hardcoded carrier handling from pattern implementations
4. Documenting multi-carrier support completion

---

## Test Case: loop_continue_multi_carrier.hako

**File**: `apps/tests/loop_continue_multi_carrier.hako`

**Pattern**: Pattern 4 (Loop with Continue)

**Structure**:
```
loop(i < 10) {
  i = i + 1
  if (i % 2 == 0) {
    continue  // Skip even numbers
  }
  sum = sum + i      // Accumulate odd numbers
  count = count + 1  // Count odd numbers
}
```

**Carriers**:
- `sum` - Accumulator for odd numbers
- `count` - Counter for odd numbers

**Expected Output**:
```
25  // sum = 1 + 3 + 5 + 7 + 9
5   // count = 5 (five odd numbers from 1 to 9)
```

**Test Command**:
```bash
./target/release/hakorune apps/tests/loop_continue_multi_carrier.hako
# Expected output:
# 25
# 5
```

---

## Integration Plan

### Step 1: Pattern 4 Lowerer Integration

**File**: `src/mir/builder/control_flow/joinir/patterns/pattern4_with_continue.rs`

**Current Approach** (to be replaced):
```rust
// OLD: Hardcoded carrier handling
boundary.host_outputs.push(sum_value_id);
boundary.join_outputs.push(join_sum_exit);
variable_map.insert("sum".to_string(), new_sum_id);
```

**New Approach**:
```rust
// NEW: Via ExitBindingBuilder
let mut builder = ExitBindingBuilder::new(&carrier_info, &exit_meta, variable_map)?;
let _bindings = builder.build_loop_exit_bindings()?;
builder.apply_to_boundary(&mut boundary)?;
```

**Changes**:
1. Import `ExitBindingBuilder` and `LoopExitBinding`
2. After `JoinModule` creation, create `CarrierInfo` and `ExitMeta`
3. Create `ExitBindingBuilder` and apply to boundary
4. Remove manual `boundary.host_outputs`/`boundary.join_outputs` manipulation

### Step 2: Pattern 3 Lowerer Integration

**File**: `src/mir/builder/control_flow/joinir/patterns/pattern3_with_if_phi.rs`

**Similar approach** to Pattern 4:
1. Collect carriers from variables assigned in if-else branches
2. Create `ExitMeta` from JoinIR exit values
3. Use `ExitBindingBuilder` to apply to boundary

---

## Validation Criteria

### Test Execution

```bash
# Basic execution
./target/release/hakorune apps/tests/loop_continue_multi_carrier.hako

# With detailed MIR output
./target/release/hakorune --dump-mir apps/tests/loop_continue_multi_carrier.hako

# With JoinIR core only
NYASH_JOINIR_CORE=1 ./target/release/hakorune apps/tests/loop_continue_multi_carrier.hako
```

### Expected Results

**Pass Criteria**:
- ✅ Output is exactly "25\n5"
- ✅ Both carriers (`sum` and `count`) have correct final values
- ✅ MIR shows proper PHI merging for exit values
- ✅ No variable map corruption (correct post-loop ValueIds)

**Fail Criteria**:
- ❌ Output is incorrect (e.g., "0\n0")
- ❌ Only one carrier is updated
- ❌ Carrier values are stale (pre-loop values)
- ❌ Variable map is corrupted

---

## Implementation Checklist

### Code Changes

- [ ] **Pattern 4 Integration**:
  - [ ] Import `ExitBindingBuilder` in pattern4_with_continue.rs
  - [ ] Create `ExitBindingBuilder` after `JoinModule` creation
  - [ ] Remove manual boundary manipulation
  - [ ] Test compilation succeeds

- [ ] **Pattern 3 Integration**:
  - [ ] Identify carriers from if-else assignments
  - [ ] Create `ExitBindingBuilder` after `JoinModule` creation
  - [ ] Apply to boundary
  - [ ] Test compilation succeeds

- [ ] **Cleanup**:
  - [ ] Remove any remaining hardcoded carrier names
  - [ ] Remove any `TODO` comments about carrier handling
  - [ ] Ensure no variable name assumptions remain

### Testing

- [ ] Run `loop_continue_multi_carrier.hako` test
- [ ] Verify output matches expected (25, 5)
- [ ] Run existing Pattern 3 & 4 tests
- [ ] Check no regressions in other loop patterns

### Documentation

- [ ] Update CURRENT_TASK.md with Phase 193-5 completion
- [ ] Add note to Phase 193 completion summary
- [ ] Document multi-carrier support completion

---

## Success Criteria for Phase 193

All sub-phases complete:

✅ **Phase 193-1**: AST Feature Extractor Box module created and delegated to by router
✅ **Phase 193-2**: CarrierInfo with flexible builder methods (automatic/explicit/manual)
✅ **Phase 193-3**: Pattern classification with diagnostic helpers
✅ **Phase 193-4**: ExitBindingBuilder fully boxified exit binding generation
⏳ **Phase 193-5**: Multi-carrier tests integrated and validated

### Phase 193 Completion Statement

Phase 193 achieves complete modularization and enhancement of JoinIR loop lowering:

1. **AST Feature Extraction**: Separated into pure function module for reusability
2. **Carrier Metadata**: Flexible construction and query methods
3. **Pattern Classification**: Diagnostic information and runtime queries
4. **Exit Bindings**: Fully boxified, eliminates hardcoded carrier handling
5. **Multi-Carrier Support**: Seamless support for loops with 2+ carriers

**Impact**: JoinIR loop lowering now has clean separation of concerns, higher reusability, and eliminates fragile hardcoded variable name assumptions.

---

## Related Documentation

- **Phase 193-4 Design**: [phase193_exit_binding_builder.md](phase193_exit_binding_builder.md)
- **Phase 193-3**: Pattern classification improvements
- **Phase 193-2**: CarrierInfo builder enhancement
- **Phase 193-1**: AST feature extractor modularization
- **Phase 188**: JoinInlineBoundary initial design
- **Phase 190**: Pattern routing architecture

---

## Notes

- **ValueId Allocation**: Currently uses `max(variable_map) + 1` strategy. Future: delegate to builder's proper ValueId allocator.
- **Debugging**: Environment variable `NYASH_TRACE_EXIT_BINDING=1` will be useful for debugging Phase 193-5 integration.
- **Next Phase**: Phase 194 can now focus on advanced pattern detection without carrier handling complexity.
Status: Historical
