From 49f0e92f2889de1923f022ea52758340d3f29787 Mon Sep 17 00:00:00 2001
From: matz <matz@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Thu, 14 Sep 2006 08:23:28 +0000
Subject: * numeric.c (fix_mul): avoid bignum multiplication as far as  
 possible.  a patch from Ondrej Bilka <neleai at seznam.cz>.  
 [ruby-core:08825]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@10934 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 numeric.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

(limited to 'numeric.c')

diff --git a/numeric.c b/numeric.c
index d5829d14a3..5014840cdb 100644
--- a/numeric.c
+++ b/numeric.c
@@ -1973,20 +1973,36 @@ fix_mul(VALUE x, VALUE y)
 /* avoids an optimization bug of HP aC++/ANSI C B3910B A.06.05 [Jul 25 2005] */
         volatile
 #endif
-	long a, b, c;
+	SIGNED_VALUE a, b;
+#if SIZEOF_VALUE * 2 <= SIZEOF_LONG_LONG
+	LONG_LONG d;
+#else
+	SIGNED_VALUE c;
 	VALUE r;
+#endif
 
 	a = FIX2LONG(x);
-	if (a == 0) return x;
-
 	b = FIX2LONG(y);
+
+#if SIZEOF_VALUE * 2 <= SIZEOF_LONG_LONG
+	d = (LONG_LONG)a * b;
+	if (FIXABLE(d)) return LONG2FIX(d);
+	return rb_ll2inum(d);
+#else
+#	define SQRT_LONG_MAX (1<<((SIZEOF_VALUE*CHAR_BIT-1)/2))
+	/*tests if N*N would overflow*/
+#	define FIT_SQRT_LONG(n) (((n)<SQRT_LONG_MAX)&&((N)>=-SQRT_LONG_MAX))
+	if (FIT_SQRT_LONG(a) && FIT_SQRT_LONG(b))
+	    return LONG2FIX(a*b);
 	c = a * b;
 	r = LONG2FIX(c);
 
+	if (a == 0) return x;
 	if (FIX2LONG(r) != c || c/a != b) {
 	    r = rb_big_mul(rb_int2big(a), rb_int2big(b));
 	}
 	return r;
+#endif
     }
     switch (TYPE(y)) {
       case T_BIGNUM:
-- 
cgit v1.2.3