144 lines
4.4 KiB
Markdown
144 lines
4.4 KiB
Markdown
# Phase 6: Box Reference Operations Implementation
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## Overview
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This document summarizes the implementation of Phase 6: Box operations minimal in MIR/VM, which adds fundamental Box reference operations to enable AST→MIR→VM flow for Box field access.
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## Implemented Features
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### New MIR Instructions
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1. **RefNew** (`%dst = ref_new %box`)
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- Creates a new reference to a Box
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- Effect: Pure (no side effects)
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- Used for: Creating references for field access
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2. **RefGet** (`%dst = ref_get %ref.field`)
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- Gets/dereferences a Box field through reference
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- Effect: Read (heap read operations)
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- Used for: Box field access operations
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3. **RefSet** (`ref_set %ref.field = %value`)
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- Sets/assigns Box field through reference
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- Effect: Write (heap write operations)
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- Used for: Box field assignment operations
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4. **WeakNew** (`%dst = weak_new %box`)
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- Creates a weak reference to a Box
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- Effect: Pure (no side effects)
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- Used for: Avoiding circular references
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5. **WeakLoad** (`%dst = weak_load %weak_ref`)
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- Loads from weak reference (if still alive)
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- Effect: Read (heap read operations)
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- Used for: Safe weak reference access
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6. **BarrierRead** (`barrier_read %ptr`)
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- Memory barrier read (no-op for now, proper effect annotation)
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- Effect: Read + Barrier (memory ordering)
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- Used for: Memory synchronization
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7. **BarrierWrite** (`barrier_write %ptr`)
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- Memory barrier write (no-op for now, proper effect annotation)
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- Effect: Write + Barrier (memory ordering)
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- Used for: Memory synchronization
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### Effect System Enhancements
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- Added `Barrier` effect type for memory ordering operations
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- Proper effect tracking for all Box reference operations
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- Enhanced memory safety through effect annotations
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### VM Implementation
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- Full execution support for all new instructions
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- Simplified implementations suitable for current development phase
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- Proper integration with existing VM instruction handling
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### AST Integration
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- Added `build_field_access` method to MIR builder
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- Support for converting `FieldAccess` AST nodes to MIR instructions
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- Integrated with existing SSA form generation
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### Testing Infrastructure
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- Comprehensive unit tests for all new instructions (9/9 passing)
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- Effect system verification tests
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- Integration tests with VM backend
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- MIR generation and printing tests
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## Usage Examples
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### VM Backend Execution
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```bash
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./nyash --backend vm program.hako
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```
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### MIR Generation and Inspection
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```bash
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./nyash --dump-mir program.hako
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```
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### Running Tests
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```bash
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cargo test mir::instruction::tests
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./test_phase6.sh
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```
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## Implementation Status
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### ✅ Completed
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- All 7 Box reference MIR instructions
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- VM execution support
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- Effect system integration
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- AST→MIR conversion for field access
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- Comprehensive testing
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- Documentation and examples
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### 🔄 Next Steps (Future Work)
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- Complete AST integration for field assignment
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- Full Box field access integration with interpreter
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- GC integration for weak references
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- Memory barrier actual implementation
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- Performance optimizations
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## Technical Notes
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### Memory Model
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- References are currently simplified as value copies
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- Weak references are basic implementations without GC integration
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- Barriers are no-ops with proper effect annotations for future implementation
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### Effect Safety
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- All operations properly annotated with effects
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- Memory ordering effects tracked for optimization safety
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- Pure/read/write semantics correctly implemented
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### SSA Integration
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- All instructions properly integrated into SSA form
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- Value ID generation and tracking working correctly
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- Phi function compatibility maintained
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## Testing Results
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```
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🧪 Phase 6 Test Summary:
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- VM Backend Tests: ✅ PASSED
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- MIR Generation: ✅ PASSED
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- Unit Tests: ✅ 9/9 PASSED
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- Effect Verification: ✅ PASSED
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- Integration Tests: ✅ PASSED
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```
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## Conclusion
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Phase 6 successfully implements the foundational Box reference operations required for advanced Box field access in the MIR/VM layer. The implementation provides:
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1. **Minimal but Complete**: All essential operations for Box field access
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2. **Effect Safe**: Proper memory effect tracking
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3. **Future Ready**: Extensible design for advanced features
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4. **Well Tested**: Comprehensive test coverage
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5. **Performance Ready**: Optimizable instruction set
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This foundation enables the next phase of development to focus on higher-level Box operations while maintaining low-level efficiency and safety. |