Eagerly allocate instance variable tables along with object

This allows us to allocate the right size for the object in advance,
meaning that we don't have to pay the cost of ivar table extension
later.  The idea is that if an object type ever became "extended" at
some point, then it is very likely it will become extended again.  So we
may as well allocate the ivar table up front.

1 files changed, 23 insertions, 0 deletions

diff --git a/benchmark/ivar_extend.yml b/benchmark/ivar_extend.yml
new file mode 100644
index 0000000000..eb9ee923f5
--- /dev/null
+++ b/benchmark/ivar_extend.yml
@@ -0,0 +1,23 @@
+prelude: |
+  class Embedded
+    def initialize
+      @a = 1
+      @b = 1
+      @c = 1
+    end
+  end
+
+  class Extended
+    def initialize
+      @a = 1
+      @b = 1
+      @c = 1
+      @d = 1
+      @e = 1
+      @f = 1
+    end
+  end
+benchmark:
+  embedded: Embedded.new
+  extended: Extended.new
+loop_count: 20_000_000