vm_method: set automatically

* vm_method.c (GLOBAL_METHOD_CACHE_MASK): set from
  GLOBAL_METHOD_CACHE_SIZE automatically.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44302 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

vm_method.c

@@ -5,8 +5,13 @@
 #ifndef GLOBAL_METHOD_CACHE_SIZE
 #define GLOBAL_METHOD_CACHE_SIZE 0x800
 #endif
+#define LSB_ONLY(x) ((x) & ~((x) - 1))
+#define POWOR_OF_2_P(x) ((x) == LSB_ONLY(x))
+#if !POWOR_OF_2_P(GLOBAL_METHOD_CACHE_SIZE)
+# error GLOBAL_METHOD_CACHE_SIZE must be power of 2
+#endif
 #ifndef GLOBAL_METHOD_CACHE_MASK
-#define GLOBAL_METHOD_CACHE_MASK 0x7ff
+#define GLOBAL_METHOD_CACHE_MASK (GLOBAL_METHOD_CACHE_SIZE-1)
 #endif
 
 #define GLOBAL_METHOD_CACHE_KEY(c,m) ((((c)>>3)^(m))&GLOBAL_METHOD_CACHE_MASK)