numeric.c: int_round_zero_p

* bignum.c (rb_big_size): add wrapper function of BIGSIZE and
  rename the method funtion with _m suffix.
* numeric.c (int_round_zero_p): extracted from rb_int_round.
  optimize for Bignum, and convert VALUE returned by Numeric#size
  to long.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@54557 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,12 @@
+Wed Apr 13 14:11:59 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* bignum.c (rb_big_size): add wrapper function of BIGSIZE and
+	  rename the method funtion with _m suffix.
+
+	* numeric.c (int_round_zero_p): extracted from rb_int_round.
+	  optimize for Bignum, and convert VALUE returned by Numeric#size
+	  to long.
+
 Wed Apr 13 12:00:08 2016  Koichi Sasada  <ko1@atdot.net>
 
 	* test/ruby/test_basicinstructions.rb: add a test to check access

bignum.c

@@ -6906,6 +6906,12 @@ rb_big_abs(VALUE x)
     return x;
 }
 
+size_t
+rb_big_size(VALUE big)
+{
+    return BIGSIZE(big);
+}
+
 /*
  *  call-seq:
  *     big.size -> integer
@@ -6919,9 +6925,9 @@ rb_big_abs(VALUE x)
  */
 
 static VALUE
-rb_big_size(VALUE big)
+rb_big_size_m(VALUE big)
 {
-    return SIZET2NUM(BIGSIZE(big));
+    return SIZET2NUM(rb_big_size(big));
 }
 
 /*
@@ -7087,7 +7093,7 @@ Init_Bignum(void)
     rb_define_method(rb_cBignum, "===", rb_big_eq, 1);
     rb_define_method(rb_cBignum, "abs", rb_big_abs, 0);
     rb_define_method(rb_cBignum, "magnitude", rb_big_abs, 0);
-    rb_define_method(rb_cBignum, "size", rb_big_size, 0);
+    rb_define_method(rb_cBignum, "size", rb_big_size_m, 0);
     rb_define_method(rb_cBignum, "bit_length", rb_big_bit_length, 0);
 
 #ifdef USE_GMP

internal.h

@@ -780,6 +780,7 @@ VALUE rb_big_uminus(VALUE x);
 VALUE rb_big_hash(VALUE);
 VALUE rb_big_odd_p(VALUE);
 VALUE rb_big_even_p(VALUE);
+size_t rb_big_size(VALUE);
 VALUE rb_integer_float_cmp(VALUE x, VALUE y);
 VALUE rb_integer_float_eq(VALUE x, VALUE y);
 VALUE rb_cstr_parse_inum(const char *str, ssize_t len, char **endp, int base);

numeric.c

@@ -109,6 +109,7 @@ static VALUE fix_lshift(long, unsigned long);
 static VALUE fix_rshift(long, unsigned long);
 static VALUE int_pow(long x, unsigned long y);
 static VALUE int_cmp(VALUE x, VALUE y);
+static int int_round_zero_p(VALUE num, int ndigits);
 static VALUE flo_truncate(VALUE num);
 static int float_invariant_round(double number, int ndigits, VALUE *num);
 
@@ -1766,6 +1767,24 @@ flo_ceil(VALUE num)
     return dbl2ival(f);
 }
 
+static int
+int_round_zero_p(VALUE num, int ndigits)
+{
+    long bytes;
+    /* If 10**N / 2 > num, then return 0 */
+    /* We have log_256(10) > 0.415241 and log_256(1/2) = -0.125, so */
+    if (FIXNUM_P(num)) {
+	bytes = sizeof(long);
+    }
+    else if (RB_TYPE_P(num, T_BIGNUM)) {
+	bytes = rb_big_size(num);
+    }
+    else {
+	bytes = NUM2LONG(rb_funcall(num, idSize, 0));
+    }
+    return (-0.415241 * ndigits - 0.125 > bytes);
+}
+
 /*
  * Assumes num is an Integer, ndigits <= 0
  */
@@ -1773,11 +1792,8 @@ VALUE
 rb_int_round(VALUE num, int ndigits)
 {
     VALUE n, f, h, r;
-    long bytes;
+
-    /* If 10**N / 2 > num, then return 0 */
+    if (int_round_zero_p(num, ndigits)) {
-    /* We have log_256(10) > 0.415241 and log_256(1/2) = -0.125, so */
-    bytes = FIXNUM_P(num) ? sizeof(long) : rb_funcall(num, idSize, 0);
-    if (-0.415241 * ndigits - 0.125 > bytes ) {
 	return INT2FIX(0);
     }