Design: Cache recently-used SuperSlab references in TLS to accelerate
ptr→SuperSlab resolution in Headerless mode free() path.
## Implementation
### New Box: core/box/tls_ss_hint_box.h
- Header-only Box (4-slot FIFO cache per thread)
- Functions: tls_ss_hint_init(), tls_ss_hint_update(), tls_ss_hint_lookup(), tls_ss_hint_clear()
- Memory overhead: 112 bytes per thread (negligible)
- Statistics API for debug builds (hit/miss counters)
### Integration Points
1. **Free path** (core/hakmem_tiny_free.inc):
- Lines 477-481: Fast path hint lookup before hak_super_lookup()
- Lines 550-555: Second lookup location (fallback path)
- Expected savings: 10-50 cycles → 2-5 cycles on cache hit
2. **Allocation path** (core/tiny_superslab_alloc.inc.h):
- Lines 115-122: Linear allocation return path
- Lines 179-186: Freelist allocation return path
- Cache update on successful allocation
3. **TLS variable** (core/hakmem_tiny_tls_state_box.inc):
- `__thread TlsSsHintCache g_tls_ss_hint = {0};`
### Build System
- **Build flag** (core/hakmem_build_flags.h):
- HAKMEM_TINY_SS_TLS_HINT (default: 0, disabled)
- Validation: requires HAKMEM_TINY_HEADERLESS=1
- **Makefile**:
- Removed old ss_tls_hint_box.o (conflicting implementation)
- Header-only design eliminates compiled object files
### Testing
- **Unit tests** (tests/test_tls_ss_hint.c):
- 6 test functions covering init, lookup, FIFO rotation, duplicates, clear, stats
- All tests PASSING
- **Build validation**:
- ✅ Compiles with hint disabled (default)
- ✅ Compiles with hint enabled (HAKMEM_TINY_SS_TLS_HINT=1)
### Documentation
- **Benchmark report** (docs/PHASE1_TLS_HINT_BENCHMARK.md):
- Implementation summary
- Build validation results
- Benchmark methodology (to be executed)
- Performance analysis framework
## Expected Performance
- **Hit rate**: 85-95% (single-threaded), 70-85% (multi-threaded)
- **Cycle savings**: 80-95% on cache hit (10-50 cycles → 2-5 cycles)
- **Target improvement**: 15-20% throughput increase vs Headerless baseline
- **Memory overhead**: 112 bytes per thread
## Box Theory
**Mission**: Cache hot SuperSlabs to avoid global registry lookup
**Boundary**: ptr → SuperSlab* or NULL (miss)
**Invariant**: hint.base ≤ ptr < hint.end → hit is valid
**Fallback**: Always safe to miss (triggers hak_super_lookup)
**Thread Safety**: TLS storage, no synchronization required
**Risk**: Low (read-only cache, fail-safe fallback, magic validation)
## Next Steps
1. Run full benchmark suite (sh8bench, cfrac, larson)
2. Measure actual hit rate with stats enabled
3. If performance target met (15-20% improvement), enable by default
4. Consider increasing cache slots if hit rate < 80%
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
210 lines
9.5 KiB
C++
210 lines
9.5 KiB
C++
// Hot-path cheap sampling counter to avoid rand() in allocation path
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// Phase 9.4: TLS single-linked freelist (mimalloc-inspired) for hottest classes (≤128B/≤256B)
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int g_tls_sll_enable = 1; // HAKMEM_TINY_TLS_SLL=0 to disable
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// Phase 6-1.7: Export TLS variables for box refactor (Box 5/6 need access from hakmem.c)
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// CRITICAL FIX: Explicit initializers prevent SEGV from uninitialized TLS in worker threads
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// PRIORITY 3: TLS Canaries - Add canaries around TLS arrays to detect buffer overruns
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#define TLS_CANARY_MAGIC 0xDEADBEEFDEADBEEFULL
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// Phase 3d-B: Unified TLS SLL (head+count in same cache line for +12-18% cache hit rate)
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#include "front/tiny_heap_v2.h"
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__thread uint64_t g_tls_canary_before_sll = TLS_CANARY_MAGIC;
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__thread TinyTLSSLL g_tls_sll[TINY_NUM_CLASSES] = {0};
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__thread uint64_t g_tls_canary_after_sll = TLS_CANARY_MAGIC;
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__thread const char* g_tls_sll_last_writer[TINY_NUM_CLASSES] = {0};
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__thread TinyHeapV2Mag g_tiny_heap_v2_mag[TINY_NUM_CLASSES] = {0};
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__thread TinyHeapV2Stats g_tiny_heap_v2_stats[TINY_NUM_CLASSES] = {0};
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static __thread int g_tls_heap_v2_initialized = 0;
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// Phase 1: TLS SuperSlab Hint Box for Headerless mode
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// Size: 112 bytes per thread (4 slots * 24 bytes + 16 bytes overhead)
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#if HAKMEM_TINY_SS_TLS_HINT
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#include "box/tls_ss_hint_box.h"
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__thread TlsSsHintCache g_tls_ss_hint = {0};
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#endif
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static int g_tiny_ultra = 0; // HAKMEM_TINY_ULTRA=1 for SLL-only ultra mode
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static int g_ultra_validate = 0; // HAKMEM_TINY_ULTRA_VALIDATE=1 to enable per-pop validation
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// Ultra debug counters
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#if HAKMEM_DEBUG_COUNTERS
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static __attribute__((unused)) uint64_t g_ultra_pop_hits[TINY_NUM_CLASSES] = {0};
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static uint64_t g_ultra_refill_calls[TINY_NUM_CLASSES] = {0};
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static __attribute__((unused)) uint64_t g_ultra_resets[TINY_NUM_CLASSES] = {0};
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#endif
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// Path counters (normal mode visibility): lightweight, for debugging/bench only
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#if HAKMEM_DEBUG_COUNTERS
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static __attribute__((unused)) uint64_t g_path_sll_pop[TINY_NUM_CLASSES] = {0};
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static __attribute__((unused)) uint64_t g_path_mag_pop[TINY_NUM_CLASSES] = {0};
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static __attribute__((unused)) uint64_t g_path_front_pop[TINY_NUM_CLASSES] = {0};
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static __attribute__((unused)) uint64_t g_path_superslab[TINY_NUM_CLASSES] = {0};
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static __attribute__((unused)) uint64_t g_path_refill_calls[TINY_NUM_CLASSES] = {0};
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// New: slow/bitmap/bump/bin instrumentation
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static __attribute__((unused)) uint64_t g_alloc_slow_calls[TINY_NUM_CLASSES] = {0};
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static __attribute__((unused)) uint64_t g_superslab_refill_calls_dbg[TINY_NUM_CLASSES] = {0};
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static __attribute__((unused)) uint64_t g_bitmap_scan_calls[TINY_NUM_CLASSES] = {0};
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static __attribute__((unused)) uint64_t g_bgbin_pops[TINY_NUM_CLASSES] = {0};
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static __attribute__((unused)) uint64_t g_bump_hits[TINY_NUM_CLASSES] = {0};
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static __attribute__((unused)) uint64_t g_bump_arms[TINY_NUM_CLASSES] = {0};
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static __attribute__((unused)) uint64_t g_spec_calls[TINY_NUM_CLASSES] = {0};
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static __attribute__((unused)) uint64_t g_spec_hits[TINY_NUM_CLASSES] = {0};
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#endif
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static int g_path_debug_enabled = 0;
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// Spill hysteresis(freeホットパスからgetenvを排除)
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static int g_spill_hyst = 32; // default margin (configured at init; never getenv on hot path)
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// Optional per-class refill batch overrides (0=use global defaults)
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static int g_refill_max_c[TINY_NUM_CLASSES] = {0};
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static int g_refill_max_hot_c[TINY_NUM_CLASSES] = {0};
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static inline __attribute__((always_inline)) int tiny_refill_max_for_class(int class_idx) {
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int v = g_refill_max_c[class_idx];
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if (v > 0) return v;
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if (class_idx <= 3) {
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int hv = g_refill_max_hot_c[class_idx];
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if (hv > 0) return hv;
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return g_tiny_refill_max_hot;
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}
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return g_tiny_refill_max;
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}
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// Phase 9.5: Frontend/Backend split - Tiny Front modules(QuickSlot / FastCache)
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#include "front/quick_slot.h"
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#include "front/fast_cache.h"
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__thread TinyFastCache g_fast_cache[TINY_NUM_CLASSES];
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static int g_frontend_enable = 0; // HAKMEM_TINY_FRONTEND=1 (experimental ultra-fast frontend)
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// SLL capacity multiplier for hot tiny classes (env: HAKMEM_SLL_MULTIPLIER)
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int g_sll_multiplier = 2;
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// Cached thread id (uint32) to avoid repeated pthread_self() in hot paths
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static __thread uint32_t g_tls_tid32;
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static __thread int g_tls_tid32_inited;
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// Phase 6-1.7: Export for box refactor (Box 6 needs access from hakmem.c)
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#ifdef HAKMEM_TINY_PHASE6_BOX_REFACTOR
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inline __attribute__((always_inline)) uint32_t tiny_self_u32(void) {
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#else
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static inline __attribute__((always_inline)) uint32_t tiny_self_u32(void) {
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#endif
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if (__builtin_expect(!g_tls_tid32_inited, 0)) {
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g_tls_tid32 = (uint32_t)(uintptr_t)pthread_self();
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g_tls_tid32_inited = 1;
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}
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return g_tls_tid32;
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}
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// Cached pthread_t as-is for APIs that require pthread_t comparison
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static __thread pthread_t g_tls_pt_self;
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static __thread int g_tls_pt_inited;
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// Frontend FastCache hit/miss counters (Small diagnostics)
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unsigned long long g_front_fc_hit[TINY_NUM_CLASSES] = {0};
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unsigned long long g_front_fc_miss[TINY_NUM_CLASSES] = {0};
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// TLS SLL class mask: bit i = 1 allows SLL for class i. Default: all 8 classes enabled.
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int g_tls_sll_class_mask = 0xFF;
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// Phase 6-1.7: Export for box refactor (Box 6 needs access from hakmem.c)
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#ifdef HAKMEM_TINY_PHASE6_BOX_REFACTOR
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inline __attribute__((always_inline)) pthread_t tiny_self_pt(void) {
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#else
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static inline __attribute__((always_inline)) pthread_t tiny_self_pt(void) {
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#endif
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if (__builtin_expect(!g_tls_pt_inited, 0)) {
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g_tls_pt_self = pthread_self();
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g_tls_pt_inited = 1;
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}
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return g_tls_pt_self;
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}
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#include "tiny_refill.h"
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// tiny_mmap_gate.h already included at top
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#include "tiny_publish.h"
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int g_sll_cap_override[TINY_NUM_CLASSES] = {0}; // LEGACY (Phase12以降は参照しない/互換用ダミー)
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// Optional prefetch on SLL pop (guarded by env: HAKMEM_TINY_PREFETCH=1)
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static int g_tiny_prefetch = 0;
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// Small-class magazine pre-initialization (to avoid cap==0 checks on hot path)
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// Hot-class small TLS magazine(実体とスイッチ)
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typedef struct {
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void* slots[128];
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uint16_t top; // 0..128
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uint16_t cap; // =128
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} TinyHotMag;
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static int g_hotmag_cap_default = 128; // default capacity (fixed)
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static int g_hotmag_refill_default = 32; // default refill batch (fixed)
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static int g_hotmag_enable = 0; // 既定OFF(ENVトグル削除済み)
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static uint16_t g_hotmag_cap_current[TINY_NUM_CLASSES];
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static uint8_t g_hotmag_cap_locked[TINY_NUM_CLASSES];
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static uint16_t g_hotmag_refill_current[TINY_NUM_CLASSES];
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static uint8_t g_hotmag_refill_locked[TINY_NUM_CLASSES];
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static uint8_t g_hotmag_class_en[TINY_NUM_CLASSES]; // 0=disabled for class, 1=enabled
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static __thread TinyHotMag g_tls_hot_mag[TINY_NUM_CLASSES];
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// Inline helpers
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#include "box/tls_sll_box.h" // Box TLS-SLL: Safe SLL operations API (needed by hotmag)
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#include "hakmem_tiny_hotmag.inc.h"
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// Diagnostics: invalid TLS SLL pointers detected (range check failures)
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_Atomic uint64_t g_tls_sll_invalid_head[TINY_NUM_CLASSES] = {0};
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_Atomic uint64_t g_tls_sll_invalid_push[TINY_NUM_CLASSES] = {0};
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_Atomic uint64_t g_tls_sll_pop_counter[TINY_NUM_CLASSES] = {0};
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// Size-specialized tiny alloc (32B/64B) via function pointers (A/B用)
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// TinyQuickSlot: 1 cache line per class (quick 6 items + small metadata)
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// Opt-in via HAKMEM_TINY_QUICK=1
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// NOTE: This type definition must come BEFORE the Phase 2D-1 includes below
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int g_quick_enable = 0; // HAKMEM_TINY_QUICK=1
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__thread TinyQuickSlot g_tls_quick[TINY_NUM_CLASSES]; // compile-out via guards below
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// Phase 2D-1: Hot-path inline function extractions(Front)
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// NOTE: TinyFastCache/TinyQuickSlot は front/ で定義済み
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#include "hakmem_tiny_hot_pop.inc.h" // 4 functions: tiny_hot_pop_class{0..3}
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#include "hakmem_tiny_refill.inc.h" // 8 functions: refill operations
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#if HAKMEM_TINY_P0_BATCH_REFILL
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#include "hakmem_tiny_refill_p0.inc.h" // P0 batch refill → FastCache 直補充
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#endif
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// Phase 7 Task 3: Pre-warm TLS cache at init
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// Pre-allocate blocks to reduce first-allocation miss penalty
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#if HAKMEM_TINY_PREWARM_TLS
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void hak_tiny_prewarm_tls_cache(void) {
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// Pre-warm each class with HAKMEM_TINY_PREWARM_COUNT blocks
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// This reduces the first-allocation miss penalty by populating TLS cache
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// Phase E1-CORRECT: ALL classes (including C7) now use TLS SLL
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for (int class_idx = 0; class_idx < TINY_NUM_CLASSES; class_idx++) {
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int count = HAKMEM_TINY_PREWARM_COUNT; // Default: 16 blocks per class
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// Trigger refill to populate TLS cache
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// P0 Fix: Use appropriate refill function based on P0 status
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#if HAKMEM_TINY_P0_BATCH_REFILL
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sll_refill_batch_from_ss(class_idx, count);
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#else
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sll_refill_small_from_ss(class_idx, count);
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#endif
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}
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}
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#endif
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// Ultra-Simple front - REMOVED (dead code cleanup 2025-11-27)
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// HotMag helpers (for classes 0..3)
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static inline int is_hot_class(int class_idx) { return class_idx >= 0 && class_idx <= 3; }
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// Optional front (HotMag) push helper: compile-out in release builds
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static inline int tiny_optional_push(int class_idx, void* ptr) {
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#if HAKMEM_BUILD_RELEASE
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(void)class_idx;
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(void)ptr;
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return 0;
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#else
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if (__builtin_expect(is_hot_class(class_idx), 0)) {
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if (__builtin_expect(hotmag_push(class_idx, ptr), 0)) {
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return 1;
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}
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}
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return 0;
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#endif
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}
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// Phase 9.6: Deferred Intelligence (event queue + background)
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// Extended event for FLINT Intelligence (lightweight; recorded off hot path only)
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// Observability, ACE, and intelligence helpers
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