hakmem/core/hakmem_tiny_free.inc

#include <inttypes.h>
#include <pthread.h>
#include "tiny_remote.h"
#include "slab_handle.h"
#include "tiny_refill.h"
#include "tiny_tls_guard.h"
#include "box/free_publish_box.h"
#include "box/tls_sll_box.h"  // Box TLS-SLL: C7-safe push/pop/splice
#include "box/tiny_next_ptr_box.h"  // Box API: next pointer read/write
#include "box/tiny_header_box.h"  // Header Box: Single Source of Truth for header operations
#include "tiny_region_id.h"  // HEADER_MAGIC, HEADER_CLASS_MASK for freelist header restoration
#include "mid_tcache.h"
#include "front/tiny_heap_v2.h"
// Phase 3d-B: TLS Cache Merge - Unified TLS SLL structure
extern __thread TinyTLSSLL g_tls_sll[TINY_NUM_CLASSES];
#if !HAKMEM_BUILD_RELEASE
#include "hakmem_tiny_magazine.h"
#endif
extern int g_tiny_force_remote;

// ENV: HAKMEM_TINY_DRAIN_TO_SLL (0=off) — adopt/bind境界でfreelist→TLS SLLへN個スプライス
static inline int tiny_drain_to_sll_budget(void) {
    static int v = -1;
    if (__builtin_expect(v == -1, 0)) {
        const char* s = getenv("HAKMEM_TINY_DRAIN_TO_SLL");
        int parsed = (s && *s) ? atoi(s) : 0;
        if (parsed < 0) parsed = 0; if (parsed > 256) parsed = 256;
        v = parsed;
    }
    return v;
}

static inline void tiny_drain_freelist_to_sll_once(SuperSlab* ss, int slab_idx, int class_idx) {
    int budget = tiny_drain_to_sll_budget();
    if (__builtin_expect(budget <= 0, 1)) return;
    // Phase E1-CORRECT: C7 now has headers, can use TLS SLL like other classes
    // (removed early return for class_idx == 7)
    if (!(ss && ss->magic == SUPERSLAB_MAGIC)) return;
    if (slab_idx < 0) return;
    TinySlabMeta* m = &ss->slabs[slab_idx];
    int moved = 0;
    while (m->freelist && moved < budget) {
        void* p = m->freelist;

        // CORRUPTION DEBUG: Validate freelist pointer before moving to TLS SLL
        if (__builtin_expect(tiny_refill_failfast_level() >= 2, 0)) {
            extern const size_t g_tiny_class_sizes[];
            size_t blk = g_tiny_class_sizes[class_idx];
            void* old_head = g_tls_sll[class_idx].head;

            // Validate p alignment
            if (((uintptr_t)p % blk) != 0) {
                fprintf(stderr, "[DRAIN_CORRUPT] Freelist ptr=%p misaligned (cls=%d blk=%zu offset=%zu)\n",
                        p, class_idx, blk, (uintptr_t)p % blk);
                fprintf(stderr, "[DRAIN_CORRUPT] Attempting to drain corrupted freelist to TLS SLL!\n");
                fprintf(stderr, "[DRAIN_CORRUPT] ss=%p slab=%d moved=%d/%d\n", ss, slab_idx, moved, budget);
                abort();
            }

            // Validate old_head alignment if not NULL
            if (old_head && ((uintptr_t)old_head % blk) != 0) {
                fprintf(stderr, "[DRAIN_CORRUPT] TLS SLL head=%p already corrupted! (cls=%d blk=%zu offset=%zu)\n",
                        old_head, class_idx, blk, (uintptr_t)old_head % blk);
                fprintf(stderr, "[DRAIN_CORRUPT] Corruption detected BEFORE drain write (ptr=%p)\n", p);
                fprintf(stderr, "[DRAIN_CORRUPT] ss=%p slab=%d moved=%d/%d\n", ss, slab_idx, moved, budget);
                abort();
            }

            fprintf(stderr, "[DRAIN_TO_SLL] cls=%d ptr=%p old_head=%p moved=%d/%d\n",
                    class_idx, p, old_head, moved, budget);
        }

        m->freelist = tiny_next_read(class_idx, p);  // Phase E1-CORRECT: Box API

        // CRITICAL FIX: Restore header BEFORE pushing to TLS SLL
        // Freelist blocks may have stale data at offset 0
        // Uses Header Box API (C1-C6 only; C0/C7 skip)
        tiny_header_write_if_preserved(p, class_idx);

        // Use Box TLS-SLL API (C7-safe push)
        // Note: C7 already rejected at line 34, so this always succeeds
        uint32_t sll_capacity = 256;  // Conservative limit
        if (tls_sll_push(class_idx, p, sll_capacity)) {
            moved++;
        } else {
            // SLL full, stop draining
            break;
        }
    }
}

static inline int tiny_remote_queue_contains_guard(SuperSlab* ss, int slab_idx, void* target) {
    if (!ss || slab_idx < 0) return 0;
    uintptr_t cur = atomic_load_explicit(&ss->remote_heads[slab_idx], memory_order_acquire);
    int limit = 8192;
    while (cur && limit-- > 0) {
        if ((void*)cur == target) {
            return 1;
        }
        uintptr_t next;
        if (__builtin_expect(g_remote_side_enable, 0)) {
            next = tiny_remote_side_get(ss, slab_idx, (void*)cur);
        } else {
            next = atomic_load_explicit((_Atomic uintptr_t*)cur, memory_order_relaxed);
        }
        cur = next;
    }
    if (limit <= 0) {
        return 1; // fail-safe: treat unbounded traversal as duplicate
    }
    return 0;
}


// Phase 6.12.1: Free with pre-calculated slab (Option C - avoids duplicate lookup)
void hak_tiny_free_with_slab(void* ptr, TinySlab* slab) {
    // Phase 7.6: slab == NULL means SuperSlab mode (Magazine integration)
    if (!slab) {
        // SuperSlab path: Get class_idx from SuperSlab
        SuperSlab* ss = hak_super_lookup(ptr);
        if (!ss || ss->magic != SUPERSLAB_MAGIC) return;
        // Derive class_idx from per-slab metadata instead of ss->size_class
        int class_idx = -1;
        void* base = (void*)((uint8_t*)ptr - 1);
        int slab_idx = slab_index_for(ss, base);
        if (slab_idx >= 0 && slab_idx < ss_slabs_capacity(ss)) {
            TinySlabMeta* meta_probe = &ss->slabs[slab_idx];
            if (meta_probe->class_idx < TINY_NUM_CLASSES) {
                class_idx = (int)meta_probe->class_idx;
            }
        }
        size_t ss_size = (size_t)1ULL << ss->lg_size;
        uintptr_t ss_base = (uintptr_t)ss;
        if (__builtin_expect(class_idx < 0 || class_idx >= TINY_NUM_CLASSES, 0)) {
            tiny_debug_ring_record(TINY_RING_EVENT_SUPERSLAB_ADOPT_FAIL, (uint16_t)0xFFu, ss, (uintptr_t)class_idx);
            return;
        }
        // Optional: cross-lookup TinySlab owner and detect class mismatch early
        // Phase E1-CORRECT: All classes have headers now, standard safe_free guard
        if (__builtin_expect(g_tiny_safe_free, 0)) {
            TinySlab* ts = hak_tiny_owner_slab(ptr);
            if (ts) {
                int ts_cls = ts->class_idx;
                if (ts_cls >= 0 && ts_cls < TINY_NUM_CLASSES && ts_cls != class_idx) {
                    uint32_t code = 0xAA00u | ((uint32_t)ts_cls & 0xFFu);
                    uintptr_t aux = tiny_remote_pack_diag(code, ss_base, ss_size, (uintptr_t)ptr);
                    tiny_debug_ring_record(TINY_RING_EVENT_REMOTE_INVALID, (uint16_t)class_idx, ptr, aux);
                    if (g_tiny_safe_free_strict) { raise(SIGUSR2); return; }
                }
            }
        }
        tiny_debug_ring_record(TINY_RING_EVENT_FREE_ENTER, (uint16_t)class_idx, ptr, 0);
        // Detect cross-thread: cross-thread free MUST go via superslab path
        // ✅ FIX: Phase E1-CORRECT - Convert USER → BASE before slab index calculation
        base = (void*)((uint8_t*)ptr - 1);
        slab_idx = slab_index_for(ss, base);
        int ss_cap = ss_slabs_capacity(ss);
        if (__builtin_expect(slab_idx < 0 || slab_idx >= ss_cap, 0)) {
            tiny_debug_ring_record(TINY_RING_EVENT_SUPERSLAB_ADOPT_FAIL, (uint16_t)0xFEu, ss, (uintptr_t)slab_idx);
            return;
        }
        TinySlabMeta* meta = &ss->slabs[slab_idx];
        if (__builtin_expect(g_tiny_safe_free, 0)) {
            size_t blk = g_tiny_class_sizes[class_idx];
            uint8_t* slab_base = tiny_slab_base_for(ss, slab_idx);
            // Phase E1-CORRECT: All classes have headers, validate block base (ptr-1) not user ptr
            uintptr_t delta = (uintptr_t)((uint8_t*)ptr - 1) - (uintptr_t)slab_base;
            int cap_ok = (meta->capacity > 0) ? 1 : 0;
            int align_ok = (delta % blk) == 0;
            int range_ok = cap_ok && (delta / blk) < meta->capacity;
            if (!align_ok || !range_ok) {
                uint32_t code = 0xA104u;
                if (align_ok) code |= 0x2u;
                if (range_ok) code |= 0x1u;
                uintptr_t aux = tiny_remote_pack_diag(code, ss_base, ss_size, (uintptr_t)ptr);
                tiny_debug_ring_record(TINY_RING_EVENT_REMOTE_INVALID, (uint16_t)class_idx, ptr, aux);
                if (g_tiny_safe_free_strict) { raise(SIGUSR2); return; }
                return;
            }
        }
        uint32_t self_tid = tiny_self_u32();
        uint8_t self_tid_low = (uint8_t)self_tid;
        if (__builtin_expect(meta->owner_tid_low != self_tid_low || meta->owner_tid_low == 0, 0)) {
            // route directly to superslab (remote queue / freelist)
            uintptr_t ptr_val = (uintptr_t)ptr;
            uintptr_t ss_base = (uintptr_t)ss;
            size_t ss_size = (size_t)1ULL << ss->lg_size;
            if (__builtin_expect(ptr_val < ss_base || ptr_val >= ss_base + ss_size, 0)) {
                tiny_debug_ring_record(TINY_RING_EVENT_SUPERSLAB_ADOPT_FAIL, (uint16_t)0xFDu, ss, ptr_val);
                return;
            }
            tiny_debug_ring_record(TINY_RING_EVENT_FREE_REMOTE, (uint16_t)class_idx, ss, (uintptr_t)ptr);
            hak_tiny_free_superslab(ptr, ss);
            HAK_STAT_FREE(class_idx);
            return;
        }

        // A/B: Force SS freelist path for same-thread frees (publish on first-free)
        do {
            static int g_free_to_ss2 = -1;
            if (__builtin_expect(g_free_to_ss2 == -1, 0)) {
                const char* e = getenv("HAKMEM_TINY_FREE_TO_SS");
                g_free_to_ss2 = (e && *e && *e != '0') ? 1 : 0; // default OFF
            }
            if (g_free_to_ss2) {
                hak_tiny_free_superslab(ptr, ss);
                HAK_STAT_FREE(class_idx);
                return;
            }
        } while (0);

        if (__builtin_expect(g_debug_fast0, 0)) {
            tiny_debug_ring_record(TINY_RING_EVENT_FRONT_BYPASS, (uint16_t)class_idx, ptr, (uintptr_t)slab_idx);
            // Phase E1-CORRECT: ALL classes (C0-C7) have 1-byte header
            void* base = (void*)((uint8_t*)ptr - 1);
            void* prev = meta->freelist;
            tiny_next_write(class_idx, base, prev);  // Box API: uses offset 1 for headers
            meta->freelist = base;
            meta->used--;
            ss_active_dec_one(ss);
            if (prev == NULL) {
                // Publish using the slab's class (per-slab class_idx)
                ss_partial_publish(class_idx, ss);
            }
            tiny_debug_ring_record(TINY_RING_EVENT_FREE_LOCAL, (uint16_t)class_idx, ptr, (uintptr_t)slab_idx);
            HAK_STAT_FREE(class_idx);
            return;
        }

        // Front-V2: try to return to TLS magazine first (A/B, default OFF)
        if (__builtin_expect(tiny_heap_v2_enabled() && class_idx <= 3, 0)) {
            void* base = (void*)((uint8_t*)ptr - 1);
            if (tiny_heap_v2_try_push(class_idx, base)) {
                tiny_debug_ring_record(TINY_RING_EVENT_FREE_FAST, (uint16_t)class_idx, ptr, slab_idx);
                HAK_STAT_FREE(class_idx);
                return;
            }
        }

        if (g_fast_enable && g_fast_cap[class_idx] != 0) {
            // Phase E1-CORRECT: ALL classes (C0-C7) have 1-byte header
            void* base = (void*)((uint8_t*)ptr - 1);
            int pushed = 0;
            if (__builtin_expect(g_fastcache_enable && class_idx <= 3, 1)) {
                pushed = fastcache_push(class_idx, base);
            } else {
                pushed = tiny_fast_push(class_idx, base);
            }
            if (pushed) {
                tiny_debug_ring_record(TINY_RING_EVENT_FREE_FAST, (uint16_t)class_idx, ptr, slab_idx);
                HAK_STAT_FREE(class_idx);
                return;
            }
        }

        if (g_tls_list_enable && class_idx != 7) {
            TinyTLSList* tls = &g_tls_lists[class_idx];
            uint32_t seq = atomic_load_explicit(&g_tls_param_seq[class_idx], memory_order_relaxed);
            if (__builtin_expect(seq != g_tls_param_seen[class_idx], 0)) {
                tiny_tls_refresh_params(class_idx, tls);
            }
            // TinyHotMag front push（8/16/32B, A/B）
            if (__builtin_expect(g_hotmag_enable && class_idx <= 2, 1)) {
                // Phase E1-CORRECT: ALL classes (C0-C7) have 1-byte header
                void* base = (void*)((uint8_t*)ptr - 1);
                if (hotmag_push(class_idx, base)) {
                    tiny_debug_ring_record(TINY_RING_EVENT_FREE_RETURN_MAG, (uint16_t)class_idx, ptr, 1);
                    HAK_STAT_FREE(class_idx);
                    return;
                }
            }
            if (tls->count < tls->cap) {
                // Phase E1-CORRECT: ALL classes (C0-C7) have 1-byte header
                void* base = (void*)((uint8_t*)ptr - 1);
                tiny_tls_list_guard_push(class_idx, tls, base);
                tls_list_push(tls, base, class_idx);
                tiny_debug_ring_record(TINY_RING_EVENT_FREE_LOCAL, (uint16_t)class_idx, ptr, 0);
                HAK_STAT_FREE(class_idx);
                return;
            }
            seq = atomic_load_explicit(&g_tls_param_seq[class_idx], memory_order_relaxed);
            if (__builtin_expect(seq != g_tls_param_seen[class_idx], 0)) {
                tiny_tls_refresh_params(class_idx, tls);
            }
            {
                // Phase E1-CORRECT: ALL classes (C0-C7) have 1-byte header
                void* base = (void*)((uint8_t*)ptr - 1);
            tiny_tls_list_guard_push(class_idx, tls, base);
            tls_list_push(tls, base, class_idx);
            }
            if (tls_list_should_spill(tls)) {
                tls_list_spill_excess(class_idx, tls);
            }
            tiny_debug_ring_record(TINY_RING_EVENT_FREE_LOCAL, (uint16_t)class_idx, ptr, 2);
            HAK_STAT_FREE(class_idx);
            return;
        }

#include "tiny_free_magazine.inc.h"
// ============================================================================
// Phase 6.23: SuperSlab Allocation Helpers
// ============================================================================

// Phase 6.24: Allocate from SuperSlab slab (lazy freelist + linear allocation)
#include "tiny_superslab_alloc.inc.h"
#include "tiny_superslab_free.inc.h"

void hak_tiny_free(void* ptr) {
    // Track total tiny free calls (diagnostics)
    extern _Atomic uint64_t g_hak_tiny_free_calls;
    atomic_fetch_add_explicit(&g_hak_tiny_free_calls, 1, memory_order_relaxed);
    if (!ptr || !g_tiny_initialized) return;

    hak_tiny_stats_poll();
    tiny_debug_ring_record(TINY_RING_EVENT_FREE_ENTER, 0, ptr, 0);

#ifdef HAKMEM_TINY_BENCH_SLL_ONLY
    // Bench-only SLL-only free: push to TLS SLL for ≤64B when possible
    {
        int class_idx = -1;
        if (g_use_superslab) {
            // Resolve class_idx from per-slab metadata instead of ss->size_class
            SuperSlab* ss = hak_super_lookup(ptr);
            if (ss && ss->magic == SUPERSLAB_MAGIC) {
                void* base = (void*)((uint8_t*)ptr - 1);
                int sidx = slab_index_for(ss, base);
                if (sidx >= 0 && sidx < ss_slabs_capacity(ss)) {
                    TinySlabMeta* m = &ss->slabs[sidx];
                    if (m->class_idx < TINY_NUM_CLASSES) {
                        class_idx = (int)m->class_idx;
                    }
                }
            }
        }
        if (class_idx < 0) {
            TinySlab* slab = hak_tiny_owner_slab(ptr);
            if (slab) class_idx = slab->class_idx;
        }
        if (class_idx >= 0 && class_idx <= 3) {
            uint32_t sll_cap = sll_cap_for_class(class_idx, (uint32_t)TINY_TLS_MAG_CAP);
            if ((int)g_tls_sll[class_idx].count < (int)sll_cap) {
                // CORRUPTION DEBUG: Validate ptr and head before TLS SLL write
                if (__builtin_expect(tiny_refill_failfast_level() >= 2, 0)) {
                    extern const size_t g_tiny_class_sizes[];
                    size_t blk = g_tiny_class_sizes[class_idx];
                    void* old_head = g_tls_sll[class_idx].head;

                    // Validate ptr alignment
                    if (((uintptr_t)ptr % blk) != 0) {
                        fprintf(stderr, "[FAST_FREE_CORRUPT] ptr=%p misaligned (cls=%d blk=%zu offset=%zu)\n",
                                ptr, class_idx, blk, (uintptr_t)ptr % blk);
                        fprintf(stderr, "[FAST_FREE_CORRUPT] Attempting to push corrupted pointer to TLS SLL!\n");
                        abort();
                    }

                    // Validate old_head alignment if not NULL
                    if (old_head && ((uintptr_t)old_head % blk) != 0) {
                        fprintf(stderr, "[FAST_FREE_CORRUPT] TLS SLL head=%p already corrupted! (cls=%d blk=%zu offset=%zu)\n",
                                old_head, class_idx, blk, (uintptr_t)old_head % blk);
                        fprintf(stderr, "[FAST_FREE_CORRUPT] Corruption detected BEFORE fast free write (ptr=%p)\n", ptr);
                        abort();
                    }

                    fprintf(stderr, "[FAST_FREE] cls=%d ptr=%p old_head=%p count=%u\n",
                            class_idx, ptr, old_head, g_tls_sll[class_idx].count);
                }

                // Use Box TLS-SLL API (C7-safe push)
                if (tls_sll_push(class_idx, ptr, sll_cap)) {
                    return;  // Success
                }
                // Fall through if push fails (SLL full or C7)
            }
        }
    }
#endif

    if (g_tiny_ultra) {
        int class_idx = -1;
        if (g_use_superslab) {
            // Resolve class_idx from per-slab metadata instead of ss->size_class
            SuperSlab* ss = hak_super_lookup(ptr);
            if (ss && ss->magic == SUPERSLAB_MAGIC) {
                void* base = (void*)((uint8_t*)ptr - 1);
                int sidx = slab_index_for(ss, base);
                if (sidx >= 0 && sidx < ss_slabs_capacity(ss)) {
                    TinySlabMeta* m = &ss->slabs[sidx];
                    if (m->class_idx < TINY_NUM_CLASSES) {
                        class_idx = (int)m->class_idx;
                    }
                }
            }
        }
        if (class_idx < 0) {
            TinySlab* slab = hak_tiny_owner_slab(ptr);
            if (slab) class_idx = slab->class_idx;
        }
        // Phase E1-CORRECT: C7 now has headers, can use TLS SLL like other classes
        if (class_idx >= 0) {
            // Ultra free: push directly to TLS SLL without magazine init
            int sll_cap = ultra_sll_cap_for_class(class_idx);
            if ((int)g_tls_sll[class_idx].count < sll_cap) {
                // CORRUPTION DEBUG: Validate ptr and head before TLS SLL write
                if (__builtin_expect(tiny_refill_failfast_level() >= 2, 0)) {
                    extern const size_t g_tiny_class_sizes[];
                    size_t blk = g_tiny_class_sizes[class_idx];
                    void* old_head = g_tls_sll[class_idx].head;

                    // Validate ptr alignment
                    if (((uintptr_t)ptr % blk) != 0) {
                        fprintf(stderr, "[ULTRA_FREE_CORRUPT] ptr=%p misaligned (cls=%d blk=%zu offset=%zu)\n",
                                ptr, class_idx, blk, (uintptr_t)ptr % blk);
                        fprintf(stderr, "[ULTRA_FREE_CORRUPT] Attempting to push corrupted pointer to TLS SLL!\n");
                        abort();
                    }

                    // Validate old_head alignment if not NULL
                    if (old_head && ((uintptr_t)old_head % blk) != 0) {
                        fprintf(stderr, "[ULTRA_FREE_CORRUPT] TLS SLL head=%p already corrupted! (cls=%d blk=%zu offset=%zu)\n",
                                old_head, class_idx, blk, (uintptr_t)old_head % blk);
                        fprintf(stderr, "[ULTRA_FREE_CORRUPT] Corruption detected BEFORE ultra free write (ptr=%p)\n", ptr);
                        abort();
                    }

                    fprintf(stderr, "[ULTRA_FREE] cls=%d ptr=%p old_head=%p count=%u\n",
                            class_idx, ptr, old_head, g_tls_sll[class_idx].count);
                }

                // Use Box TLS-SLL API (C7-safe push)
                // Note: C7 already rejected at line 334
                {
                    // Phase E1-CORRECT: ALL classes (C0-C7) have 1-byte header
                    void* base = (void*)((uint8_t*)ptr - 1);
                    if (tls_sll_push(class_idx, base, (uint32_t)sll_cap)) {
                        // CORRUPTION DEBUG: Verify write succeeded
                        if (__builtin_expect(tiny_refill_failfast_level() >= 2, 0)) {
                            void* readback = tiny_next_read(class_idx, base);  // Phase E1-CORRECT: Box API
                            (void)readback;
                            void* new_head = g_tls_sll[class_idx].head;
                            if (new_head != base) {
                                fprintf(stderr, "[ULTRA_FREE_CORRUPT] Write verification failed! base=%p new_head=%p\n",
                                        base, new_head);
                                abort();
                            }
                        }
                        return;  // Success
                    }
                }
                // Fall through if push fails (SLL full)
            }
        }
        // Fallback to existing path if class resolution fails
    }

    SuperSlab* fast_ss = NULL;
    TinySlab* fast_slab = NULL;
    int fast_class_idx = -1;
    if (g_use_superslab) {
        fast_ss = hak_super_lookup(ptr);
        if (fast_ss && fast_ss->magic == SUPERSLAB_MAGIC) {
            void* base = (void*)((uint8_t*)ptr - 1);
            int sidx = slab_index_for(fast_ss, base);
            if (sidx >= 0 && sidx < ss_slabs_capacity(fast_ss)) {
                TinySlabMeta* m = &fast_ss->slabs[sidx];
                if (m->class_idx < TINY_NUM_CLASSES) {
                    fast_class_idx = (int)m->class_idx;
                }
            }
            if (fast_class_idx < 0) {
                fast_ss = NULL;
            }
        } else {
            fast_ss = NULL;
        }
    }
    if (fast_class_idx < 0) {
        fast_slab = hak_tiny_owner_slab(ptr);
        if (fast_slab) fast_class_idx = fast_slab->class_idx;
    }
    // Safety: detect class mismatch (SS vs TinySlab) early
    if (__builtin_expect(g_tiny_safe_free && fast_class_idx >= 0, 0)) {
        int ss_cls = -1, ts_cls = -1;
        SuperSlab* chk_ss = fast_ss ? fast_ss : (g_use_superslab ? hak_super_lookup(ptr) : NULL);
        if (chk_ss && chk_ss->magic == SUPERSLAB_MAGIC) {
            void* base = (void*)((uint8_t*)ptr - 1);
            int sidx = slab_index_for(chk_ss, base);
            if (sidx >= 0 && sidx < ss_slabs_capacity(chk_ss)) {
                TinySlabMeta* m = &chk_ss->slabs[sidx];
                if (m->class_idx < TINY_NUM_CLASSES) {
                    ss_cls = (int)m->class_idx;
                }
            }
        }
        TinySlab* chk_slab = fast_slab ? fast_slab : hak_tiny_owner_slab(ptr);
        if (chk_slab) ts_cls = chk_slab->class_idx;
        if (ss_cls >= 0 && ts_cls >= 0 && ss_cls != ts_cls) {
            uintptr_t packed = ((uintptr_t)(uint16_t)ss_cls << 16) | (uint16_t)ts_cls;
            tiny_debug_ring_record(TINY_RING_EVENT_REMOTE_INVALID, (uint16_t)fast_class_idx, ptr, packed);
            if (g_tiny_safe_free_strict) { raise(SIGUSR2); return; }
        }
    }
    if (fast_class_idx >= 0) {
        tiny_debug_ring_record(TINY_RING_EVENT_FREE_ENTER, (uint16_t)fast_class_idx, ptr, 1);
    }
    if (fast_class_idx >= 0 && g_fast_enable && g_fast_cap[fast_class_idx] != 0) {
        // Phase E1-CORRECT: ALL classes (C0-C7) have 1-byte header
        void* base2 = (void*)((uint8_t*)ptr - 1);
        // PRIORITY 1: Try FastCache first (bypasses SLL when Front-Direct)
        int pushed = 0;
        if (__builtin_expect(g_fastcache_enable && fast_class_idx <= 3, 1)) {
            pushed = fastcache_push(fast_class_idx, base2);
        } else {
            pushed = tiny_fast_push(fast_class_idx, base2);
        }
        if (pushed) {
            tiny_debug_ring_record(TINY_RING_EVENT_FREE_FAST, (uint16_t)fast_class_idx, ptr, 0);
            HAK_STAT_FREE(fast_class_idx);
            return;
        }
    }

    // SuperSlab detection: prefer fast mask-based check when available
    SuperSlab* ss = fast_ss;
    if (!ss && g_use_superslab) {
        ss = hak_super_lookup(ptr);
        if (!(ss && ss->magic == SUPERSLAB_MAGIC)) {
            ss = NULL;
        }
    }
    if (ss && ss->magic == SUPERSLAB_MAGIC) {
        // Derive class from per-slab meta
        int cls = -1;
        void* base = (void*)((uint8_t*)ptr - 1);
        int sidx = slab_index_for(ss, base);
        if (sidx >= 0 && sidx < ss_slabs_capacity(ss)) {
            TinySlabMeta* m = &ss->slabs[sidx];
            if (m->class_idx < TINY_NUM_CLASSES) {
                cls = (int)m->class_idx;
            }
        }
        if (cls < 0) {
            if (g_tiny_safe_free_strict) { raise(SIGUSR2); }
            return;
        }
        hak_tiny_free_superslab(ptr, ss);
        HAK_STAT_FREE(cls);
        return;
    }

    // Fallback to TinySlab only when SuperSlab is not in use
    TinySlab* slab = fast_slab;
    if (!slab) slab = hak_tiny_owner_slab(ptr);
    if (!slab) return;  // Not managed by Tiny Pool
    if (__builtin_expect(g_use_superslab, 0)) {
        // In SS mode, a pointer that resolves only to TinySlab is suspicious → treat as invalid free
        tiny_debug_ring_record(TINY_RING_EVENT_REMOTE_INVALID, 0xEE, ptr, 0xF1u);
        if (g_tiny_safe_free_strict) { raise(SIGUSR2); return; }
        return;
    }

    hak_tiny_free_with_slab(ptr, slab);
}

// ============================================================================
// EXTRACTED TO hakmem_tiny_query.c (Phase 2B-1)
// ============================================================================
// EXTRACTED: int hak_tiny_is_managed(void* ptr) {
// EXTRACTED:     if (!ptr || !g_tiny_initialized) return 0;
// EXTRACTED:     // Phase 6.12.1: O(1) slab lookup via registry/list
// EXTRACTED:     return hak_tiny_owner_slab(ptr) != NULL || hak_super_lookup(ptr) != NULL;
// EXTRACTED: }

// Phase 7.6: Check if pointer is managed by Tiny Pool (TinySlab OR SuperSlab)
// EXTRACTED: int hak_tiny_is_managed_superslab(void* ptr) {
// EXTRACTED:     if (!ptr || !g_tiny_initialized) return 0;
// EXTRACTED: 
// EXTRACTED:     // Safety: Only check if g_use_superslab is enabled
// EXTRACTED:     if (g_use_superslab) {
// EXTRACTED:         SuperSlab* ss = hak_super_lookup(ptr);
// EXTRACTED:         // Phase 8.2 optimization: Use alignment check instead of mincore()
// EXTRACTED:         // SuperSlabs are always SUPERSLAB_SIZE-aligned (2MB)
// EXTRACTED:         if (ss && ((uintptr_t)ss & (SUPERSLAB_SIZE - 1)) == 0) {
// EXTRACTED:             if (ss->magic == SUPERSLAB_MAGIC) {
// EXTRACTED:                 return 1;  // Valid SuperSlab pointer
// EXTRACTED:             }
// EXTRACTED:         }
// EXTRACTED:     }
// EXTRACTED: 
// EXTRACTED:     // Fallback to TinySlab check
// EXTRACTED:     return hak_tiny_owner_slab(ptr) != NULL;
// EXTRACTED: }

// Return the usable size for a Tiny-managed pointer (0 if unknown/not tiny).
// Prefer SuperSlab metadata when available; otherwise use TinySlab owner class.
// EXTRACTED: size_t hak_tiny_usable_size(void* ptr) {
// EXTRACTED:     if (!ptr || !g_tiny_initialized) return 0;
// EXTRACTED: 
// EXTRACTED:     // Check SuperSlab first via registry (safe under direct link and LD)
// EXTRACTED:     if (g_use_superslab) {
// EXTRACTED:         SuperSlab* ss = hak_super_lookup(ptr);
// EXTRACTED:         if (ss && ss->magic == SUPERSLAB_MAGIC) {
// EXTRACTED:             int k = (int)ss->size_class;
// EXTRACTED:             if (k >= 0 && k < TINY_NUM_CLASSES) {
// EXTRACTED:                 return g_tiny_class_sizes[k];
// EXTRACTED:             }
// EXTRACTED:         }
// EXTRACTED:     }
// EXTRACTED: 
// EXTRACTED:     // Fallback: TinySlab owner lookup
// EXTRACTED:     TinySlab* slab = hak_tiny_owner_slab(ptr);
// EXTRACTED:     if (slab) {
// EXTRACTED:         int k = slab->class_idx;
// EXTRACTED:         if (k >= 0 && k < TINY_NUM_CLASSES) {
// EXTRACTED:             return g_tiny_class_sizes[k];
// EXTRACTED:         }
// EXTRACTED:     }
// EXTRACTED:     return 0;
// EXTRACTED: }


// ============================================================================
// Statistics and Debug Functions - Extracted to hakmem_tiny_stats.c
// ============================================================================
// (Phase 2B API headers moved to top of file)


// Optional shutdown hook to stop background components (e.g., Intelligence Engine)
void hak_tiny_shutdown(void) {
    // Release TLS SuperSlab references (dec refcount) before stopping BG/INT
    for (int k = 0; k < TINY_NUM_CLASSES; k++) {
        TinyTLSSlab* tls = &g_tls_slabs[k];
        if (tls->ss) {
            superslab_ref_dec(tls->ss);
            tls->ss = NULL;
            tls->meta = NULL;
            tls->slab_base = NULL;
        }
    }
    if (g_bg_bin_started) {
        g_bg_bin_stop = 1;
        if (!pthread_equal(tiny_self_pt(), g_bg_bin_thread)) {
            pthread_join(g_bg_bin_thread, NULL);
        }
        g_bg_bin_started = 0;
        g_bg_bin_enable = 0;
    }
    tiny_obs_shutdown();
    if (g_int_engine && g_int_started) {
        g_int_stop = 1;
        // Best-effort join; avoid deadlock if called from within the thread
        if (!pthread_equal(tiny_self_pt(), g_int_thread)) {
            pthread_join(g_int_thread, NULL);
        }
        g_int_started = 0;
        g_int_engine = 0;
    }
}





// Always-available: Trim empty slabs (release fully-free slabs)