hakmem/docs/STATUS_2025_12_03_CURRENT.md

# Project Status - 2025-12-03

**Last Updated**: 2025-12-03 (Current)
**Status**: 🔴 CRITICAL BLOCKER - TLS SLL Header Corruption Detected
**Overall Phase**: Phase 1 Implementation + Phase 2 Design (Blocked)

---

## Summary

The hakmem memory allocator project has reached a critical stability issue during Phase 1 performance benchmarking. The baseline configuration crashes with a TLS SLL header corruption error that affects **all configurations**, indicating a shared code path problem rather than a Phase 1 specific issue.

---

## Completed Phases ✅

### Phase 0: Type Safety & Box Architecture Framework
- ✅ Phantom Types implementation (`ptr_type_box.h`)
- ✅ Pointer conversion API (`ptr_conversion_box.h`)
- ✅ Root cause analysis verified (Gemini's mathematical proof)
- ✅ Box theory framework established
- ✅ Include order dependencies resolved (commit 2dc9d5d59)
- ✅ Magazine Spill pointer wrapping fixed (commit f3f75ba3d)

### Phase 1: Logic Centralization & Optimization (TLS Hint Box)
- ✅ Designed TLS SuperSlab Hint Box (`tls_ss_hint_box.h`)
- ✅ Implemented 5-function API (init, lookup, update, clear, stats)
- ✅ Integrated into free path (lines 477-481, 550-555)
- ✅ Integrated into alloc path (lines 115-122, 179-186)
- ✅ Created 6 unit tests - **ALL PASSING**
- ✅ Compiled as header-only (zero overhead when disabled)
- ⚠️ Performance benchmarking: Only 2.3% improvement vs target 15-20%

### Phase 2: Headerless Mode Design
- ✅ Comprehensive design document (21KB)
- ✅ All 7 task specifications documented
- ✅ A/B toggle flag designed (HAKMEM_TINY_HEADERLESS)
- ✅ SuperSlab Registry integration planned
- ✅ TLS SLL validation skipping documented
- ❌ **BLOCKED**: Cannot proceed - baseline instability

---

## Current Critical Issue 🔴

### Symptom

```
[TLS_SLL_HDR_RESET] cls=1 base=0x7ef296abf8c8 got=0x31 expect=0xa1 count=0
Segmentation fault (core dumped)
```

### Location

- **File**: `core/box/tls_sll_box.h`
- **Lines**: 282-303
- **Function**: `tls_sll_pop_impl()`
- **Operation**: Header validation during free path

### Impact

- ❌ TC1 (Baseline) crashes after ~22 seconds of execution
- ❌ Cannot validate Phase 1 performance improvements
- ❌ Cannot proceed to Phase 2 implementation
- ❌ Cannot benchmark any configuration variant

### Root Cause

**Unknown** - One of six documented patterns:

1. RAW pointer vs BASE pointer type mismatch
2. Header offset mismatch (write vs read location)
3. Atomic fence missing (compiler/CPU reordering)
4. Adjacent block overflow corrupting header
5. Class index mismatch during push/pop
6. Headerless mode interference

---

## Documents Created for Diagnosis

Three comprehensive documents have been created to guide the fix:

1. **`docs/CHATGPT_CONTEXT_SUMMARY.md`**
   - Quick facts about the problem
   - Architecture overview
   - File locations and data structures
   - Timeline estimate: 4-8 hours

2. **`docs/CHATGPT_HANDOFF_TLS_DIAGNOSIS.md`**
   - Step-by-step 7-step task breakdown
   - Detailed instructions for each phase
   - Expected validation criteria
   - Success metrics

3. **`docs/TLS_SLL_HEADER_CORRUPTION_DIAGNOSIS.md`** (Existing, 1,150+ lines)
   - Deep dive into all 6 root cause patterns
   - Code examples for each pattern
   - Minimal test case template
   - Diagnostic logging instrumentation
   - Fix code templates
   - 7-step validation procedure

---

## What Needs to Happen

### Immediate (Blocking)

1. **[CHATGPT TASK]** Diagnose TLS SLL header corruption
   - Use the three diagnostic documents
   - Follow 7-step process
   - Expected delivery: 4-8 hours
   - Success criterion: TC1 baseline completes without crashes

### After Diagnosis

2. **[DEPENDS ON #1]** Validate Phase 1 performance
   - Run full benchmarks (TC1, TC2, TC3)
   - Confirm TLS Hint Box improves performance
   - Identify optimization opportunities

3. **[DEPENDS ON #1]** Proceed to Phase 2
   - Implement Headerless mode (ON/OFF toggle)
   - Validate alignment guarantees
   - Benchmark performance trade-offs

4. **[DEPENDS ON #1-3]** Phase 102 Planning
   - Design MemApi bridge
   - Connect hakmem to nyrt Ring0 runtime

---

## Recent Git History

```
ad852e5d5 - Priority-2 ENV Cache: hakmem_batch.c (1変数追加、1箇所置換)
b741d61b4 - Priority-2 ENV Cache: hakmem_debug.c (1変数追加、1箇所置換)
22a67e5ca - Priority-2 ENV Cache: hakmem_smallmid.c (1変数追加、1箇所置換)
f0e77a000 - Priority-2 ENV Cache: hakmem_tiny.c (3箇所置換)
183b10673 - Priority-2 ENV Cache: Shared Pool Release (1箇所置換)

[Earlier commits in THIS session:]
94f9ea51  - Implement TLS SuperSlab Hint Box (Phase 1) ✅
           - Header-only implementation (256 lines)
           - 5 function APIs
           - 6 unit tests - ALL PASSING
           - Benchmarked at only 2.3% improvement

f3f75ba3d - Fix Magazine Spill RAW pointer type conversion ✅
           - Added HAK_BASE_FROM_RAW() wrapping
           - hakmem_tiny_refill.inc.h:228
           - Verified with cfrac/sh8bench

2dc9d5d59 - Fix include order in hakmem.c ✅
           - Moved hak_kpi_util.inc.h before hak_core_init.inc.h
           - Resolved undefined reference errors
           - Clean build verified
```

---

## File Statistics

| Category | Count | Status |
|----------|-------|--------|
| **Core Implementation** | 47 files | ✅ Compiles |
| **Box Components** | 15 files | ✅ Box theory applied |
| **Test Suite** | 23 tests | ⚠️ 6 TLS Hint tests PASS, 17 others untested due to crash |
| **Documentation** | 12 documents | ✅ Comprehensive |
| **Build Artifacts** | libhakmem.so | ✅ Generates (547 KB) |

---

## Build Status

```
$ make clean && make shared -j8
✅ Compilation: SUCCESS
✅ Linking: SUCCESS
✅ Output: ./libhakmem.so (547 KB)
✅ Debug symbols: Included (-g flag)

$ LD_PRELOAD=./libhakmem.so ./mimalloc-bench/out/bench/sh8bench
❌ Execution: SEGFAULT
Error: [TLS_SLL_HDR_RESET] cls=1 base=0x... got=0x31 expect=0xa1
Exit Code: 139 (SIGSEGV)
Runtime: ~22 seconds before crash
```

---

## Key Metrics

| Metric | Value | Status |
|--------|-------|--------|
| **Compilation Time** | 8-12 sec | ✅ Good |
| **Executable Size** | 547 KB | ✅ Reasonable |
| **Baseline Performance** | N/A | ❌ Crashes |
| **Phase 1 Optimization** | 2.3% | ⚠️ Below target (15-20%) |
| **Code Coverage** | Unknown | ⏳ Pending baseline fix |

---

## Next Steps (Clearly Defined)

### For ChatGPT (Immediate Handoff)

**Task**: Diagnose and fix TLS SLL header corruption

**Documents to Use**:
1. `docs/CHATGPT_CONTEXT_SUMMARY.md` - Quick reference
2. `docs/CHATGPT_HANDOFF_TLS_DIAGNOSIS.md` - Step-by-step instructions
3. `docs/TLS_SLL_HEADER_CORRUPTION_DIAGNOSIS.md` - Deep reference

**Steps**:
1. Read diagnostic documents
2. Create minimal reproducer
3. Add diagnostic logging
4. Run diagnostic test
5. Identify root cause pattern
6. Implement surgical fix (1-5 lines)
7. Validate with TC1 baseline test

**Success Criterion**:
- ✅ sh8bench runs to completion
- ✅ cfrac runs without errors
- ✅ No TLS_SLL_HDR_RESET errors
- ✅ < 5% performance regression

---

## Notes for Future Reference

### Architecture Decisions Locked In

1. **Box Theory**: Each component is isolated with clear APIs
2. **Phantom Types**: Type safety in Debug mode, zero-cost in Release
3. **Pointer Conversion**: Centralized in `ptr_conversion_box.h`
4. **Layout Definitions**: Centralized in `tiny_layout_box.h`
5. **TLS SLL**: Thread-local single-linked list with header validation
6. **SuperSlab Registry**: Maps free pointers to class information (Phase 2)

### Known Working Patterns

- Magazine Spill RAW→BASE wrapping (fixed)
- Include order dependencies (fixed)
- Unit test framework (6 TLS Hint tests passing)
- Box header-only compilation (verified)

### Known Issues Needing Diagnosis

- TLS SLL header corruption (PRIMARY BLOCKER)
- Phase 1 performance below target (SECONDARY - optimization opportunity)
- Headerless mode not yet validated (DEPENDS ON PRIMARY FIX)

---

## Handoff Status

✅ **All diagnostic documents prepared**
✅ **Comprehensive step-by-step instructions created**
✅ **Root cause patterns documented with code examples**
✅ **Minimal test case template provided**
✅ **Validation procedures detailed**

🎯 **Ready for ChatGPT handoff**

Next: Pass the three documents to ChatGPT with the directive to follow the 7-step process.

---

## Questions for Next Phase

After the fix is complete, the following should be investigated:

1. Why is Phase 1 performance only 2.3% improvement vs expected 15-20%?
   - Is 4 slots enough for the cache?
   - Are there secondary bottlenecks?
   - Does perf/cachegrind show cache misses?

2. Can Phase 2 Headerless provide better performance than Phase 1?
   - What are the trade-offs?
   - Is the SuperSlab Registry lookup overhead worth it?

3. How does hakmem compare to mimalloc and jemalloc across different workloads?
   - Are there specific use cases where hakmem excels?
   - Where does it fall short?

---

**Status**: 🔴 CRITICAL - Awaiting ChatGPT diagnosis and fix

**Estimated Resolution Time**: 4-8 hours from ChatGPT engagement

**Next Review**: After ChatGPT completes TLS SLL diagnosis and fix