add rb_hash_new_with_size()

Sometimes, size of a hash can be calcluated a priori.  By providing
such info to the constructor we can avoid unnecessary internal re-
allocations.  This can boost for instance creation of hash literals.
[Bug #13861]

Signed-off-by: Urabe, Shyouhei <shyouhei@ruby-lang.org>


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59744 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 1 insertions, 1 deletions

diff --git a/vm.c b/vm.c
index 1da03c4566..0bf3707f3a 100644
--- a/vm.c
+++ b/vm.c
@@ -2694,7 +2694,7 @@ m_core_hash_from_ary(VALUE self, VALUE ary)
 static VALUE
 core_hash_from_ary(VALUE ary)
 {
-    VALUE hash = rb_hash_new();
+    VALUE hash = rb_hash_new_with_size(RARRAY_LEN(ary) / 2);
 
     RUBY_DTRACE_CREATE_HOOK(HASH, (Check_Type(ary, T_ARRAY), RARRAY_LEN(ary)));
     return core_hash_merge_ary(hash, ary);