tenderlove	2016-09-13 00:40:09 +0900 (Tue, 13 Sep 2016)

  New Revision: 56144

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=56144

  Log:
    Copy the serial number from the super class to the singleton class
    
    This helps hit inline method caches more frequently.  Before this
    commit:
    
    ```
    [aaron@TC ruby (trunk)]$ time ./ruby -v benchmark/bm_vm2_poly_singleton.rb
    ruby 2.4.0dev (2016-09-12 trunk 56141) [x86_64-darwin15]
    
    real  0m3.679s
    user  0m3.632s
    sys 0m0.022s
    ```
    
    After this commit:
    
    ```
    [aaron@TC ruby (trunk)]$ time ./ruby -v benchmark/bm_vm2_poly_singleton.rb
    ruby 2.4.0dev (2016-09-12 trunk 56141) [x86_64-darwin15]
    last_commit=Copy the serial number from the super class to the singleton class
    
    real  0m2.246s
    user  0m2.203s
    sys 0m0.020s
    ```
    
    [Feature #12364]
    [ruby-core:75425]

  Added files:
    trunk/benchmark/bm_vm2_poly_singleton.rb
  Modified files:
    trunk/ChangeLog
    trunk/class.c
Index: benchmark/bm_vm2_poly_singleton.rb
===================================================================
--- benchmark/bm_vm2_poly_singleton.rb	(revision 0)
+++ benchmark/bm_vm2_poly_singleton.rb	(revision 56144)
@@ -0,0 +1,14 @@ https://github.com/ruby/ruby/blob/trunk/benchmark/bm_vm2_poly_singleton.rb#L1
+class C1
+  def m; 1; end
+end
+
+o1 = C1.new
+o2 = C1.new
+o2.singleton_class
+
+i = 0
+while i<6_000_000 # benchmark loop 2
+  o = (i % 2 == 0) ? o1 : o2
+  o.m; o.m; o.m; o.m; o.m; o.m; o.m; o.m
+  i += 1
+end
Index: ChangeLog
===================================================================
--- ChangeLog	(revision 56143)
+++ ChangeLog	(revision 56144)
@@ -1,3 +1,9 @@ https://github.com/ruby/ruby/blob/trunk/ChangeLog#L1
+Tue Sep 13 00:39:47 2016  Aaron Patterson <tenderlove@r...>
+
+	* class.c (singleton_class_of): Copy superclass serial number to
+	  singleton class.  This improves singleton class IMC hit rates.
+	  [Feature #12364] [ruby-core:75425]
+
 Mon Sep 12 13:46:23 2016  Anton Davydov  <mail@d...>
 
 	* lib/uri/mailto.rb: Removed needless `return` and use `.`` instead of `::`
Index: class.c
===================================================================
--- class.c	(revision 56143)
+++ class.c	(revision 56144)
@@ -1591,7 +1591,9 @@ singleton_class_of(VALUE obj) https://github.com/ruby/ruby/blob/trunk/class.c#L1591
     klass = RBASIC(obj)->klass;
     if (!(FL_TEST(klass, FL_SINGLETON) &&
 	  rb_ivar_get(klass, id_attached) == obj)) {
+	rb_serial_t serial = RCLASS_SERIAL(klass);
 	klass = rb_make_metaclass(obj, klass);
+	RCLASS_SERIAL(klass) = serial;
     }
 
     if (OBJ_TAINTED(obj)) {

--
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