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Fix TLS index and virtual reservation leaks on DLL unload #1261

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jinpzhanAMD wants to merge 2 commits into from
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Fix TLS index and virtual reservation leaks on DLL unload #1261

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03689ec
enable mi_option_destroy_on_exit
Apr 10, 2026
02d1596
fix win32 shutdown cleanup
Apr 14, 2026
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31 changes: 27 additions & 4 deletions src/init.c
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Original file line number Diff line number Diff line change
Expand Up @@ -546,6 +546,7 @@ static void mi_subprocs_unsafe_destroy_all(void) {
}
}
mi_subproc_unsafe_destroy(&subproc_main);
_mi_arenas_unsafe_destroy_all(&subproc_main); // free main subproc arenas (needed for DLL unload)
}


Expand Down Expand Up @@ -772,8 +773,13 @@ mi_decl_hidden size_t _mi_theap_default_expansion_slot = MI_TLS_INITIAL_EXPANSIO
mi_decl_hidden size_t _mi_theap_cached_slot = MI_TLS_INITIAL_SLOT;
mi_decl_hidden size_t _mi_theap_cached_expansion_slot = MI_TLS_INITIAL_EXPANSION_SLOT;

static size_t mi_win_tls_slot_alloc(size_t* extended) {
// Raw TLS indices for cleanup via TlsFree (avoids reverse-engineering the stored slot)
static DWORD mi_tls_raw_default = TLS_OUT_OF_INDEXES;
static DWORD mi_tls_raw_cached = TLS_OUT_OF_INDEXES;

static size_t mi_win_tls_slot_alloc(size_t* extended, DWORD* raw_tls_index) {
const DWORD slot = TlsAlloc();
if (raw_tls_index != NULL) { *raw_tls_index = slot; }
if (slot==TLS_OUT_OF_INDEXES || slot >= MI_TLS_DIRECT_SLOTS + MI_TLS_EXPANSION_SLOTS - 1) {
// note: we also fail if the program already allocated the maximum number of expansion slots (as we use the last one as the default)
*extended = 0;
Expand All @@ -797,15 +803,28 @@ static size_t mi_win_tls_slot_alloc(size_t* extended) {
mi_decl_cold mi_theap_t* _mi_win_tls_slots_init(void) {
static mi_atomic_once_t tls_slots_init;
if (mi_atomic_once(&tls_slots_init)) {
_mi_theap_default_slot = mi_win_tls_slot_alloc(&_mi_theap_default_expansion_slot);
_mi_theap_cached_slot = mi_win_tls_slot_alloc(&_mi_theap_cached_expansion_slot);
_mi_theap_default_slot = mi_win_tls_slot_alloc(&_mi_theap_default_expansion_slot, &mi_tls_raw_default);
_mi_theap_cached_slot = mi_win_tls_slot_alloc(&_mi_theap_cached_expansion_slot, &mi_tls_raw_cached);
if (_mi_theap_cached_slot==0) {
_mi_error_message(EFAULT, "unable to allocate fast TLS user slot (0x%zx)\n", _mi_theap_cached_slot);
}
}
return (mi_theap_t*)&_mi_theap_empty;
}

static void mi_win_tls_slots_done(void) {
if (mi_tls_raw_default != TLS_OUT_OF_INDEXES) {
TlsFree(mi_tls_raw_default);
mi_tls_raw_default = TLS_OUT_OF_INDEXES;
}
if (mi_tls_raw_cached != TLS_OUT_OF_INDEXES) {
TlsFree(mi_tls_raw_cached);
mi_tls_raw_cached = TLS_OUT_OF_INDEXES;
}
_mi_theap_default_slot = MI_TLS_INITIAL_SLOT;
_mi_theap_cached_slot = MI_TLS_INITIAL_SLOT;
}

static void mi_win_tls_slot_set(size_t slot, size_t extended_slot, void* value) {
mi_assert_internal((slot >= MI_TLS_DIRECT_FIRST && slot < MI_TLS_DIRECT_FIRST + MI_TLS_DIRECT_SLOTS) || slot == MI_TLS_EXPANSION_SLOT);
if (slot < MI_TLS_DIRECT_FIRST + MI_TLS_DIRECT_SLOTS) {
Expand Down Expand Up @@ -1014,7 +1033,8 @@ void mi_process_init(void) mi_attr_noexcept {
// #endif
if (!mi_atomic_once(&process_init)) return;
_mi_verbose_message("process init: 0x%zx\n", _mi_thread_id());

// Release reserved page-map and arena allocations at process shutdown for verifier runs.
mi_option_enable(mi_option_destroy_on_exit);
mi_detect_cpu_features();
_mi_options_init();
_mi_stats_init();
Expand Down Expand Up @@ -1091,6 +1111,9 @@ void mi_cdecl mi_process_done(void) mi_attr_noexcept {
mi_subproc_stats_print_out(NULL, NULL, NULL);
}
mi_lock_done(&subprocs_lock);
#if MI_TLS_MODEL_DYNAMIC_WIN32
mi_win_tls_slots_done();
#endif
_mi_allocator_done();
_mi_verbose_message("process done: 0x%zx\n", tld_main.thread_id);
os_preloading = true; // don't call the C runtime anymore
Expand Down