remove `NON_SCALAR_THREAD_ID` support

`NON_SCALAR_THREAD_ID` shows `pthread_t` is non-scalar (non-pointer)
and only s390x is known platform. However, the supporting code is
very complex and it is only used for deubg print information.

So this patch removes the support of `NON_SCALAR_THREAD_ID`
and make the code simple.

thread.c

@@ -270,34 +270,6 @@ void rb_thread_debug(const char *fmt, ...);
 #define POSITION_ARGS
 #endif
 
-# ifdef NON_SCALAR_THREAD_ID
-#define fill_thread_id_string ruby_fill_thread_id_string
-const char *
-ruby_fill_thread_id_string(rb_nativethread_id_t thid, rb_thread_id_string_t buf)
-{
-    extern const char ruby_digitmap[];
-    size_t i;
-
-    buf[0] = '0';
-    buf[1] = 'x';
-    for (i = 0; i < sizeof(thid); i++) {
-# ifdef LITTLE_ENDIAN
-	size_t j = sizeof(thid) - i - 1;
-# else
-	size_t j = i;
-# endif
-	unsigned char c = (unsigned char)((char *)&thid)[j];
-	buf[2 + i * 2] = ruby_digitmap[(c >> 4) & 0xf];
-	buf[3 + i * 2] = ruby_digitmap[c & 0xf];
-    }
-    buf[sizeof(rb_thread_id_string_t)-1] = '\0';
-    return buf;
-}
-#   define fill_thread_id_str(th) fill_thread_id_string((th)->thread_id, (th)->thread_id_string)
-#   define thread_id_str(th) ((th)->thread_id_string)
-#   define PRI_THREAD_ID "s"
-# endif
-
 # if THREAD_DEBUG < 0
 static int rb_thread_debug_enabled;
 
@@ -336,12 +308,8 @@ rb_thread_s_debug_set(VALUE self, VALUE val)
 #define thread_debug if(0)printf
 #endif
 
-#ifndef fill_thread_id_str
-# define fill_thread_id_string(thid, buf) ((void *)(uintptr_t)(thid))
-# define fill_thread_id_str(th) (void)0
-# define thread_id_str(th) ((void *)(uintptr_t)(th)->nt->thread_id)
-# define PRI_THREAD_ID "p"
-#endif
+#define thread_id_str(th) ((void *)(uintptr_t)(th)->nt->thread_id)
+#define PRI_THREAD_ID "p"
 
 MAYBE_UNUSED(NOINLINE(static int thread_start_func_2(rb_thread_t *th, VALUE *stack_start)));
 void ruby_sigchld_handler(rb_vm_t *); /* signal.c */
@@ -380,9 +348,6 @@ rb_thread_debug(
 {
     va_list args;
     char buf[BUFSIZ];
-#ifdef NON_SCALAR_THREAD_ID
-    rb_thread_id_string_t thread_id_string;
-#endif
 
     if (!rb_thread_debug_enabled) return;
 

thread_none.c

@@ -130,7 +130,6 @@ Init_native_thread(rb_thread_t *main_th)
 {
     // no TLS setup and no thread id setup
     ruby_thread_set_native(main_th);
-    fill_thread_id_str(main_th);
 }
 
 static void

thread_pthread.c

@@ -51,10 +51,15 @@
 #  define USE_EVENTFD (0)
 #endif
 
+#ifdef NON_SCALAR_THREAD_ID
+  #define DEBUG_OUT_NT_ID (NULL)
+#else
+  #define DEBUG_OUT_NT_ID ((void *)pthread_self())
+#endif
+
 #define DEBUG_OUT() \
   pthread_mutex_lock(&debug_mutex); \
-  printf(POSITION_FORMAT"%"PRI_THREAD_ID" - %s" POSITION_ARGS, \
-	 fill_thread_id_string(pthread_self(), thread_id_string), buf);	\
+  printf(POSITION_FORMAT"%"PRI_THREAD_ID" - %s" POSITION_ARGS, DEBUG_OUT_NT_ID, buf);	\
   fflush(stdout); \
   pthread_mutex_unlock(&debug_mutex);
 
@@ -717,7 +722,6 @@ Init_native_thread(rb_thread_t *main_th)
     // setup main thread
     main_th->nt->thread_id = pthread_self();
     ruby_thread_set_native(main_th);
-    fill_thread_id_str(main_th);
     native_thread_init(main_th->nt);
 }
 
@@ -1069,7 +1073,6 @@ thread_start_func_1(void *th_ptr)
 	VALUE stack_start;
 #endif
 
-	fill_thread_id_str(th);
 #if defined USE_NATIVE_THREAD_INIT
 	native_thread_init_stack(th);
 #endif
@@ -1173,7 +1176,6 @@ use_cached_thread(rb_thread_t *th)
         entry->th = th;
         /* th->nt->thread_id must be set before signal for Thread#name= */
         th->nt->thread_id = entry->thread_id;
-        fill_thread_id_str(th);
         rb_native_cond_signal(&entry->cond);
     }
     rb_native_mutex_unlock(&thread_cache_lock);
@@ -1237,7 +1239,6 @@ native_thread_create(rb_thread_t *th)
         err = pthread_create(&th->nt->thread_id, &attr, thread_start_func_1, th);
 	thread_debug("create: %p (%d)\n", (void *)th, err);
 	/* should be done in the created thread */
-	fill_thread_id_str(th);
 	CHECK_ERR(pthread_attr_destroy(&attr));
     }
     return err;

thread_pthread.h

@@ -30,10 +30,6 @@ struct rb_native_thread {
 
     rb_nativethread_id_t thread_id;
 
-#ifdef NON_SCALAR_THREAD_ID
-    rb_thread_id_string_t thread_id_string;
-#endif
-
 #ifdef RB_THREAD_T_HAS_NATIVE_ID
     int tid;
 #endif

vm.c

@@ -3275,10 +3275,6 @@ th_init(rb_thread_t *th, VALUE self, rb_vm_t *vm)
     th->top_self = vm->top_self; // 0 while self == 0
     th->value = Qundef;
 
-#if  defined(NON_SCALAR_THREAD_ID) && !defined(__wasm__) && !defined(__EMSCRIPTEN__)
-    th->nt->thread_id_string[0] = '\0';
-#endif
-
     th->ec->errinfo = Qnil;
     th->ec->root_svar = Qfalse;
     th->ec->local_storage_recursive_hash = Qnil;

vm_core.h

@@ -896,8 +896,6 @@ typedef struct rb_ensure_list {
     struct rb_ensure_entry entry;
 } rb_ensure_list_t;
 
-typedef char rb_thread_id_string_t[sizeof(rb_nativethread_id_t) * 2 + 3];
-
 typedef struct rb_fiber_struct rb_fiber_t;
 
 struct rb_waiting_list {

vm_dump.c

@@ -1180,10 +1180,6 @@ rb_vm_bugreport(const void *ctx)
     }
 }
 
-#ifdef NON_SCALAR_THREAD_ID
-const char *ruby_fill_thread_id_string(rb_nativethread_id_t thid, rb_thread_id_string_t buf);
-#endif
-
 void
 rb_vmdebug_stack_dump_all_threads(void)
 {
@@ -1193,9 +1189,7 @@ rb_vmdebug_stack_dump_all_threads(void)
     // TODO: now it only shows current ractor
     ccan_list_for_each(&r->threads.set, th, lt_node) {
 #ifdef NON_SCALAR_THREAD_ID
-        rb_thread_id_string_t buf;
-	ruby_fill_thread_id_string(th->nt->thread_id, buf);
-	fprintf(stderr, "th: %p, native_id: %s\n", th, buf);
+	fprintf(stderr, "th: %p, native_id: N/A\n", th);
 #else
         fprintf(stderr, "th: %p, native_id: %p\n", (void *)th, (void *)(uintptr_t)th->nt->thread_id);
 #endif