refactor hash literal

Same as rb_ary_tmp_new_from_values(), it reduces vm_exec_core binary
size from 26,176 bytes to 26,080 bytes.  But this time, also with a
bit of optimizations:

  - Because we are allocating a new hash and no back references are
    introduced at all, we can safely skip write barriers.

  - Also, the iteration never recurs.  We can avoid complicated
    function callbacks by using st_insert instead of st_update.

----

	* hash.c (rb_hash_new_from_values): refactor
          extract the bulk insert into a function.

	* hash.c (rb_hash_new_from_object): also refactor.

	* hash.c (rb_hash_s_create): use the new functions.

	* insns.def (newhash): ditto.

	* vm.c (core_hash_from_ary): ditto.

	* iternal.h: export the new function.

-----------------------------------------------------------
benchmark results:
minimum results in each 7 measurements.
Execution time (sec)
name    before  after
loop_whileloop2  0.135  0.134
vm2_bighash*     1.236  0.687

Speedup ratio: compare with the result of `before' (greater is better)
name    after
loop_whileloop2 1.008
vm2_bighash*    1.798


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58427 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 5 insertions, 8 deletions

diff --git a/insns.def b/insns.def
index a056b221d5..36ba48eaea 100644
--- a/insns.def
+++ b/insns.def
@@ -492,16 +492,13 @@ newhash
 (...)
 (VALUE val) // inc += 1 - num;
 {
-    rb_num_t i;
-
     RUBY_DTRACE_CREATE_HOOK(HASH, num);
 
-    val = rb_hash_new();
-
-    for (i = num; i > 0; i -= 2) {
-	const VALUE v = TOPN(i - 2);
-	const VALUE k = TOPN(i - 1);
-	rb_hash_aset(val, k, v);
+    if (num) {
+	val = rb_hash_new_from_values(num, STACK_ADDR_FROM_TOP(num));
+    }
+    else {
+	val = rb_hash_new();
     }
     POPN(num);
 }