From dd723771c118da71aa58bb74537cacaec425542a Mon Sep 17 00:00:00 2001
From: Koichi Sasada <ko1@atdot.net>
Date: Fri, 29 Nov 2019 03:02:44 +0900
Subject: fastpath for ivar read of FL_EXIVAR objects.

vm_getivar() provides fastpath for T_OBJECT by caching an index
of ivar. This patch also provides fastpath for FL_EXIVAR objects.
FL_EXIVAR objects have an each ivar array and index can be cached
as T_OBJECT. To access this ivar array, generic_iv_tbl is exposed
by rb_ivar_generic_ivtbl() (declared in variable.h which is newly
introduced).

Benchmark script:

Benchmark.driver(repeat_count: 3){|x|
  x.executable name: 'clean', command: %w'../clean/miniruby'
  x.executable name: 'trunk', command: %w'./miniruby'

  objs = [Object.new, 'str', {a: 1, b: 2}, [1, 2]]

  objs.each.with_index{|obj, i|
    rep = obj.inspect
    rep = 'Object.new' if /\#/ =~ rep
    x.prelude str = %Q{
      v#{i} = #{rep}
      def v#{i}.foo
        @iv # ivar access method (attr_reader)
      end
      v#{i}.instance_variable_set(:@iv, :iv)
    }
    puts str
    x.report %Q{
      v#{i}.foo
    }
  }
}

Result:

      v0.foo # T_OBJECT

               clean:  85387141.8 i/s
               trunk:  85249373.6 i/s - 1.00x  slower

      v1.foo # T_STRING

               trunk:  57894407.5 i/s
               clean:  39957178.6 i/s - 1.45x  slower

      v2.foo # T_HASH

               trunk:  56629413.2 i/s
               clean:  39227088.9 i/s - 1.44x  slower

      v3.foo # T_ARRAY

               trunk:  55797530.2 i/s
               clean:  38263572.9 i/s - 1.46x  slower
---
 test/ruby/test_variable.rb | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

(limited to 'test/ruby/test_variable.rb')

diff --git a/test/ruby/test_variable.rb b/test/ruby/test_variable.rb
index f14b4019df..0772066143 100644
--- a/test/ruby/test_variable.rb
+++ b/test/ruby/test_variable.rb
@@ -178,6 +178,25 @@ class TestVariable < Test::Unit::TestCase
     end
   end
 
+  class ExIvar < Hash
+    def initialize
+      @a = 1
+      @b = 2
+      @c = 3
+    end
+
+    def ivars
+      [@a, @b, @c]
+    end
+  end
+
+  def test_external_ivars
+    3.times{
+      # check inline cache for external ivar access
+      assert_equal [1, 2, 3], ExIvar.new.ivars
+    }
+  end
+
   def test_local_variables_with_kwarg
     bug11674 = '[ruby-core:71437] [Bug #11674]'
     v = with_kwargs_11(v1:1,v2:2,v3:3,v4:4,v5:5,v6:6,v7:7,v8:8,v9:9,v10:10,v11:11)
-- 
cgit v1.2.3