Use FL_TEST_RAW in rb_hash_default_value

jhawthorn · jhawthorn · commit bf6099bd40f1 · 2022-12-17T14:26:13.000-08:00
We should always have a T_HASH here, so we can use FL_TEST_RAW to avoid
checking whether we may have an immediate value.

I expect this to be a very small performance improvement (perf stat
./miniruby benchmark/hash_aref_miss.rb shows a ~1% improvement). It also
removes 9 instructions from rb_hash_default_value on x86_64.
diff --git a/hash.c b/hash.c
@@ -2088,9 +2088,11 @@ rb_hash_default_unredefined(VALUE hash)
 VALUE
 rb_hash_default_value(VALUE hash, VALUE key)
 {
+    RUBY_ASSERT(RB_TYPE_P(hash, T_HASH));
+
     if (LIKELY(rb_hash_default_unredefined(hash))) {
         VALUE ifnone = RHASH_IFNONE(hash);
-        if (!FL_TEST(hash, RHASH_PROC_DEFAULT)) return ifnone;
+        if (LIKELY(!FL_TEST_RAW(hash, RHASH_PROC_DEFAULT))) return ifnone;
         if (UNDEF_P(key)) return Qnil;
         return call_default_proc(ifnone, hash, key);
     }

Original file line number	Diff line number	Diff line change
`@@ -2088,9 +2088,11 @@ rb_hash_default_unredefined(VALUE hash)`
`2088`	`2088`	`VALUE`
`2089`	`2089`	`rb_hash_default_value(VALUE hash, VALUE key)`
`2090`	`2090`	`{`
	`2091`	`+ RUBY_ASSERT(RB_TYPE_P(hash, T_HASH));`
	`2092`	`+`
`2091`	`2093`	`if (LIKELY(rb_hash_default_unredefined(hash))) {`
`2092`	`2094`	`VALUE ifnone = RHASH_IFNONE(hash);`
`2093`		`- if (!FL_TEST(hash, RHASH_PROC_DEFAULT)) return ifnone;`
	`2095`	`+ if (LIKELY(!FL_TEST_RAW(hash, RHASH_PROC_DEFAULT))) return ifnone;`
`2094`	`2096`	`if (UNDEF_P(key)) return Qnil;`
`2095`	`2097`	`return call_default_proc(ifnone, hash, key);`
`2096`	`2098`	`}`