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, 10 insertions, 21 deletions

diff --git a/vm.c b/vm.c
index e64c072fdc..968f2dbf3e 100644
--- a/vm.c
+++ b/vm.c
@@ -2646,7 +2646,6 @@ m_core_set_postexe(VALUE self)
     return Qnil;
 }
 
-static VALUE core_hash_merge_ary(VALUE hash, VALUE ary);
 static VALUE core_hash_from_ary(VALUE ary);
 static VALUE core_hash_merge_kwd(int argc, VALUE *argv);
 
@@ -2656,7 +2655,6 @@ core_hash_merge(VALUE hash, long argc, const VALUE *argv)
     long i;
 
     Check_Type(hash, T_HASH);
-    VM_ASSERT(argc % 2 == 0);
     for (i=0; i<argc; i+=2) {
 	rb_hash_aset(hash, argv[i], argv[i+1]);
     }
@@ -2674,27 +2672,18 @@ m_core_hash_from_ary(VALUE self, VALUE ary)
 static VALUE
 core_hash_from_ary(VALUE ary)
 {
-    VALUE hash = rb_hash_new();
+    long n;
 
-    RUBY_DTRACE_CREATE_HOOK(HASH, (Check_Type(ary, T_ARRAY), RARRAY_LEN(ary)));
-    return core_hash_merge_ary(hash, ary);
-}
-
-#if 0
-static VALUE
-m_core_hash_merge_ary(VALUE self, VALUE hash, VALUE ary)
-{
-    REWIND_CFP(core_hash_merge_ary(hash, ary));
-    return hash;
-}
-#endif
-
-static VALUE
-core_hash_merge_ary(VALUE hash, VALUE ary)
-{
     Check_Type(ary, T_ARRAY);
-    core_hash_merge(hash, RARRAY_LEN(ary), RARRAY_CONST_PTR(ary));
-    return hash;
+    n = RARRAY_LEN(ary);
+    RUBY_DTRACE_CREATE_HOOK(HASH, n);
+    if (n) {
+        VM_ASSERT(n % 2 == 0);
+        return rb_hash_new_from_values(n, RARRAY_PTR(ary));
+    }
+    else {
+        return rb_hash_new();
+    }
 }
 
 static VALUE