hakorune/docs/development/current/main/phase202-summary.md

Phase 202: Pattern 1-4 JoinValueSpace Unification

Status: ✅ Complete Date: 2025-12-09 Commits:

• 6e778948 Phase 202-A (Pattern 1)
• 98e81b26 Phase 202-B (Pattern 3)
• ae741d97 Phase 202-C (Pattern 4)

Overview

Phase 202 unified all JoinIR loop patterns (Pattern 1-4) to use the JoinValueSpace system introduced in Phase 201, eliminating manual ValueId allocation counters and ensuring complete ValueId collision safety through region separation.

Motivation

Phase 201 successfully migrated Pattern 2 to JoinValueSpace, revealing the benefits of unified ValueId allocation:

• Safety: Disjoint regions (PHI/Param/Local) prevent collisions
• Consistency: Single allocation mechanism across all patterns
• Maintainability: No manual counter management
• Debuggability: Clear region boundaries (100, 1000)

Phase 202 extended this to the remaining patterns (1, 3, 4) to achieve complete architectural consistency.

Implementation Summary

Phase 202-A: Pattern 1 (Simple While)

File Changes:

• simple_while_minimal.rs: Replace value_counter with JoinValueSpace
• pattern1_minimal.rs: Create and pass JoinValueSpace to lowerer
• loop_view_builder.rs: Create JoinValueSpace in router

ValueId Usage:

Region	Usage
PHI Reserved (0-99)	❌ Not used
Param (100-999)	❌ Not used (no ConditionEnv)
Local (1000+)	✅ All temps (Const, Compare, UnaryOp)

Why Pattern 1 is simpler: No break conditions → No ConditionEnv → No Param region needed

Test Results:

$ cargo test --release --lib pattern
✅ 119 passed

$ ./target/release/hakorune apps/tests/loop_min_while.hako
✅ Output: "0 1 2"

Phase 202-B: Pattern 3 (If-Else PHI)

File Changes:

• loop_with_if_phi_minimal.rs: Replace value_counter with JoinValueSpace
• pattern3_with_if_phi.rs: Create and pass JoinValueSpace to lowerer
• loop_patterns/with_if_phi.rs: Update legacy wrapper

ValueId Usage:

Region	Usage
PHI Reserved (0-99)	❌ Not used
Param (100-999)	❌ Not used (PHI values from ConditionEnv)
Local (1000+)	✅ All temps (PHI, Select, BinOp)

Test Results:

$ cargo test --release --lib if_phi
✅ 5/5 passed

$ ./target/release/hakorune apps/tests/loop_if_phi.hako
✅ Output: "9" (sum)

$ ./target/release/hakorune apps/tests/loop_if_phi_continue.hako
✅ Output: "9" (sum with continue)

Phase 202-C: Pattern 4 (Continue)

File Changes:

• loop_with_continue_minimal.rs: Replace dual counters with JoinValueSpace
• pattern4_with_continue.rs: Create and pass JoinValueSpace to lowerer

Dual Counter Problem (Before):

// Two separate counters - collision risk!
let mut value_counter = 0u32;
let mut join_value_counter = 0u32; // Manually incremented

Unified Allocation (After):

// Single source of truth - no collision possible
let mut join_value_space = JoinValueSpace::new();
let mut alloc_value = || join_value_space.alloc_local();
let mut alloc_param = || join_value_space.alloc_param();

ValueId Usage:

Region	Usage
PHI Reserved (0-99)	❌ Not used
Param (100-999)	✅ ConditionEnv variables
Local (1000+)	✅ All temps (Select, BinOp, Const)

Test Results:

$ cargo test --release --lib continue
✅ 11 passed (3 ignored)

$ ./target/release/hakorune apps/tests/loop_continue_pattern4.hako
✅ Output: "25" (single carrier)

$ ./target/release/hakorune apps/tests/loop_continue_multi_carrier.hako
✅ Output: "100\n10" (multi carrier)

Comparison Table: Before vs After

Before Phase 202 (Manual Counters)

Pattern	Allocation Method	Collision Risk
Pattern 1	value_counter = 0u32	⚠️ Yes (overlaps with ConditionEnv if added)
Pattern 2	value_counter = 0u32	⚠️ Yes (collided with Param region)
Pattern 3	value_counter = 0u32	⚠️ Yes (overlaps with ConditionEnv if added)
Pattern 4	value_counter + join_value_counter	⚠️ Yes (dual counter management)

After Phase 202 (JoinValueSpace)

Pattern	Allocation Method	Collision Risk
Pattern 1	JoinValueSpace.alloc_local()	✅ No (Local region isolated)
Pattern 2	JoinValueSpace.alloc_param() + alloc_local()	✅ No (Param/Local disjoint)
Pattern 3	JoinValueSpace.alloc_local()	✅ No (Local region isolated)
Pattern 4	JoinValueSpace.alloc_param() + alloc_local()	✅ No (Param/Local disjoint)

Region Usage Matrix

Pattern	PHI (0-99)	Param (100-999)	Local (1000+)
Pattern 1	❌	❌	✅ Const, Compare, UnaryOp
Pattern 2	❌	✅ ConditionEnv, CarrierInfo	✅ Const, BinOp, temps
Pattern 3	❌	❌	✅ PHI, Select, BinOp
Pattern 4	❌	✅ ConditionEnv (continue vars)	✅ Select, BinOp, temps

Key Insight: Patterns 1 and 3 only need Local region (simple structure), while Patterns 2 and 4 need both Param and Local regions (complex condition analysis).

Benefits Achieved

1. Safety

• ValueId collision impossible: Disjoint regions (PHI/Param/Local) guarantee no overlap
• Contract enforcement: Debug-mode assertions catch violations early
• Future-proof: Easy to add new allocation patterns within regions

2. Consistency

• Single allocation mechanism: All patterns use JoinValueSpace
• Unified API: alloc_param() / alloc_local() across all patterns
• Maintainable: No pattern-specific counter logic

3. Debuggability

• Clear region boundaries: ValueId ranges reveal allocation source
  • 100-999 → "This is a Param (ConditionEnv/CarrierInfo)"
  • 1000+ → "This is a Local (intermediate value)"
• Traceable: JoinValueSpace provides single point of debug logging

4. Code Quality

• 75 lines removed (Phase 203-A dead code cleanup)
• No manual counter management: Eliminated error-prone increment logic
• Pattern 4 dual counter eliminated: Simplified from 2 counters to 1 allocator

Test Coverage

Build Status

$ cargo build --release --lib
✅ Success (0 errors, 4 warnings)

Unit Tests

$ cargo test --release --lib
✅ 821 passed; 0 failed; 64 ignored

E2E Tests (Representative Cases)

Test File	Pattern	Expected Output	Result
loop_min_while.hako	P1	"0 1 2"	✅ PASS
minimal_ssa_bug_loop.hako	P2	RC: 0	✅ PASS
loop_if_phi.hako	P3	"9"	✅ PASS
loop_continue_pattern4.hako	P4	"25"	✅ PASS
loop_continue_multi_carrier.hako	P4	"100\n10"	✅ PASS
phase200d_capture_minimal.hako	P2	"30"	✅ PASS

No regressions: All existing tests continue to pass.

Architecture Impact

Invariant Strengthening

Added to Section 1.9 of joinir-architecture-overview.md:

• ValueId space diagram (PHI/Param/Local regions)
• Component-to-region mapping table
• Design principles (fixed boundaries, reserve_phi vs alloc_phi)
• Relationship with value_id_ranges.rs (module-level vs intra-lowering)

Component Updates

All pattern lowerers now follow the same structure:

pub fn lower_pattern_X(
    // ... pattern-specific params
    join_value_space: &mut JoinValueSpace,
) -> Result<JoinModule, ...> {
    let mut alloc_local = || join_value_space.alloc_local();
    let mut alloc_param = || join_value_space.alloc_param();
    // ... lowering logic
}

Callers create JoinValueSpace before calling lowerer:

let mut join_value_space = JoinValueSpace::new();
let result = lower_pattern_X(..., &mut join_value_space)?;

Related Work

Phase 201 (Foundation)

• Introduced JoinValueSpace box
• Migrated Pattern 2 as reference implementation
• Established Param/Local region separation
• Validated with 821 unit tests

Phase 203-A (Cleanup)

• Removed obsolete v1 API (70 lines)
• Converted 3 unit tests to v2 API
• Removed 2 unused imports
• Documented stub functions

Future Phases (Phase 204+)

• Pattern 5 (Trim/JsonParser) integration
• Advanced carrier analysis with JoinValueSpace
• Potential PHI reservation usage (currently unused)

Commit History

6e778948 feat(joinir): Phase 202-A Pattern 1 uses JoinValueSpace
98e81b26 feat(joinir): Phase 202-B Pattern 3 uses JoinValueSpace
ae741d97 feat(joinir): Phase 202-C Pattern 4 uses JoinValueSpace, unify dual counters

References

• Phase 201: JoinValueSpace design and Pattern 2 migration
• JoinValueSpace Implementation: src/mir/join_ir/lowering/join_value_space.rs
• Pattern Lowerers:
  • simple_while_minimal.rs (Pattern 1)
  • loop_with_break_minimal.rs (Pattern 2)
  • loop_with_if_phi_minimal.rs (Pattern 3)
  • loop_with_continue_minimal.rs (Pattern 4)
• Architecture Overview: joinir-architecture-overview.md Section 1.9
• Design Document: phase201-join-value-space-design.md
• Pattern 1 Details: phase202-a-pattern1-joinvaluespace.md

Conclusion

Phase 202 achieved complete architectural consistency across all JoinIR loop patterns by migrating Pattern 1, 3, and 4 to the unified JoinValueSpace system. This eliminates all ValueId collision risks, simplifies maintenance, and establishes a solid foundation for future JoinIR enhancements.

Key Achievement: 4/4 patterns (100%) now use JoinValueSpace, with 0 manual counter systems remaining in the codebase.