resolve class name earlier and more consistently

This further avoids class name resolution issues which came
about due to relying on hash table ordering before r53376.

Pre-caching the class name when it is never used raises memory
use, but the overall gain from moving away from st still gives
us a small gain.  Reverting r53376 and this patch and testing with
"valgrind -v ./ruby -rrdoc -eexit" on x86 (32-bit) shows:

before:
    in use at exit: 1,662,239 bytes in 25,286 blocks
  total heap usage: 49,514 allocs, 24,228 frees, 6,005,561 bytes allocated

after, with this change:
    in use at exit: 1,646,529 bytes in 24,572 blocks
  total heap usage: 48,891 allocs, 24,319 frees, 6,003,921 bytes allocated

* class.c (Init_class_hierarchy): resolve name for rb_cObject ASAP
* object.c (rb_mod_const_set): move name resolution to rb_const_set
* variable.c (rb_const_set): do class resolution here
  [ruby-core:72807] [Bug #11977]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53518 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,10 @@
+Wed Jan 13 03:42:58 2016  Eric Wong  <e@80x24.org>
+
+	* class.c (Init_class_hierarchy): resolve name for rb_cObject ASAP
+	* object.c (rb_mod_const_set): move name resolution to rb_const_set
+	* variable.c (rb_const_set): do class resolution here
+	  [ruby-core:72807] [Bug #11977]
+
 Wed Jan 13 00:37:12 2016  Satoshi Ohmori  <sachin21dev@gmail.com>
 
 	* man/ruby.1: fix double word typo.  [Fix GH-1194]

class.c

@@ -547,6 +547,10 @@ Init_class_hierarchy(void)
 {
     rb_cBasicObject = boot_defclass("BasicObject", 0);
     rb_cObject = boot_defclass("Object", rb_cBasicObject);
+
+    /* resolve class name ASAP for order-independence */
+    rb_class_name(rb_cObject);
+
     rb_cModule = boot_defclass("Module", rb_cObject);
     rb_cClass =  boot_defclass("Class",  rb_cModule);
 

object.c

@@ -2178,13 +2178,6 @@ rb_mod_const_set(VALUE mod, VALUE name, VALUE value)
     if (!id) id = rb_intern_str(name);
     rb_const_set(mod, id, value);
 
-    /*
-     * Resolve and cache class name immediately to resolve ambiguity
-     * and avoid order-dependency on const_tbl
-     */
-    if (RB_TYPE_P(value, T_MODULE) || RB_TYPE_P(value, T_CLASS)) {
-	rb_class_name(value);
-    }
     return value;
 }
 

variable.c

@@ -2569,6 +2569,13 @@ rb_const_set(VALUE klass, ID id, VALUE val)
 	args.value = val;
 	const_tbl_update(&args);
     }
+    /*
+     * Resolve and cache class name immediately to resolve ambiguity
+     * and avoid order-dependency on const_tbl
+     */
+    if (rb_cObject && (RB_TYPE_P(val, T_MODULE) || RB_TYPE_P(val, T_CLASS))) {
+	rb_class_name(val);
+    }
 }
 
 static void