Task 176-1: Pattern2 limitation investigation
- Identified 10 limitation points where only position carrier was handled
- Added TODO markers for Phase 176-2/3 implementation
- Created phase176-pattern2-limitations.md documentation
Task 176-2: CarrierUpdateLowerer helper implementation
- Implemented emit_carrier_update() helper function
- Supports CounterLike and AccumulationLike UpdateExpr patterns
- Added 6 unit tests (all passing)
- Fail-Fast error handling for carrier/variable not found
Task 176-3: Pattern2 lowerer multi-carrier extension
- Extended header PHI generation for all carriers
- Implemented loop update for all carriers using emit_carrier_update()
- Extended ExitLine/ExitMeta construction for all carriers
- Updated function call/jump args to include all carriers
- 9/10 tests passing (1 pre-existing test issue)
Task 176-4: E2E testing and bug fixes
- Fixed Trim pattern loop_var_name overwrite bug (pattern2_with_break.rs)
- Fixed InstructionRewriter latch_incoming mapping bug
- All E2E tests passing (RC=0): pos + result dual-carrier loops work
- test_jsonparser_parse_string_min2.hako verified
Task 176-5: Documentation updates
- Created phase176-completion-report.md
- Updated phase175-multicarrier-design.md with completion status
- Updated joinir-architecture-overview.md roadmap
- Updated CURRENT_TASK.md with Phase 176 completion + Phase 177 TODO
- Updated loop_pattern_space.md F-axis (multi-carrier support complete)
Technical achievements:
- Pattern2 now handles single/multiple carriers uniformly
- CarrierInfo architecture proven to work end-to-end
- Two critical bugs fixed (loop_var overwrite, latch_incoming mapping)
- No regressions in existing tests
Next: Phase 177 - Apply to JsonParser _parse_string full implementation
Builder pattern for JoinInlineBoundary construction, reduces field manipulation scattering.
# Changes
- NEW: src/mir/join_ir/lowering/inline_boundary_builder.rs (165 lines)
- JoinInlineBoundaryBuilder with 7 fluent methods
- Complete unit test coverage (4 tests)
- MODIFIED: src/mir/join_ir/lowering/mod.rs (+2 lines)
- Export inline_boundary_builder module
- Public re-export of JoinInlineBoundaryBuilder
- MODIFIED: src/mir/builder/control_flow/joinir/patterns/pattern2_with_break.rs
- Replace direct boundary field manipulation with builder pattern
- 9 lines of field assignments → fluent builder chain
# Benefits
- **Centralized**: All boundary construction logic in builder
- **Readable**: Fluent API shows construction intent clearly
- **Maintainable**: Changes to boundary structure isolated to builder
- **Type Safe**: Builder validates field consistency
# Tests
✅ All builder unit tests pass (4/4)
✅ All pattern module tests pass (30+)
✅ Library build succeeds with no errors
🤖 Generated with Claude Code (https://claude.com/claude-code)
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
