* math.c (math_gamma): get rid of direct comparison between too

big double and integer, with gcc on x86_64.  [ruby-core:25257]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@24738 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+Wed Sep  2 16:49:53 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* math.c (math_gamma): get rid of direct comparison between too
+	  big double and integer, with gcc on x86_64.  [ruby-core:25257]
+
 Wed Sep  2 13:47:30 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* math.c (domain_check): simplified.

math.c

@@ -13,6 +13,8 @@
 #include <math.h>
 #include <errno.h>
 
+#define numberof(array) (int)(sizeof(array) / sizeof((array)[0]))
+
 VALUE rb_mMath;
 
 extern VALUE rb_to_float(VALUE val);
@@ -663,13 +665,14 @@ math_gamma(VALUE obj, VALUE x)
     };
     double d0, d;
     double intpart, fracpart;
+    int n;
     Need_Float(x);
     d0 = RFLOAT_VALUE(x);
     fracpart = modf(d0, &intpart);
     if (fracpart == 0.0 &&
-            0 < intpart &&
-            (size_t)intpart <= sizeof(fact_table)/sizeof(*fact_table)) {
-        return DBL2NUM(fact_table[(int)intpart - 1]);
+	0 < intpart &&
+	(n = (int)intpart - 1) < numberof(fact_table)) {
+        return DBL2NUM(fact_table[n]);
     }
     errno = 0;
     d = tgamma(d0);

test/ruby/test_math.rb

@@ -1,6 +1,10 @@
 require 'test/unit'
 
 class TestMath < Test::Unit::TestCase
+  def assert_infinity(a, *rest)
+    assert(!a.finite?, *rest)
+  end
+
   def check(a, b)
     err = [Float::EPSILON * 4, [a.abs, b.abs].max * Float::EPSILON * 256].max
     assert_in_delta(a, b, err)
@@ -189,6 +193,13 @@ class TestMath < Test::Unit::TestCase
     check(2, Math.gamma(3))
     check(15 * sqrt_pi / 8, Math.gamma(3.5))
     check(6, Math.gamma(4))
+
+    # no SEGV [ruby-core:25257]
+    31.upto(65) do |i|
+      i = 1 << i
+      assert_infinity(Math.gamma(i))
+      assert_infinity(Math.gamma(i-1))
+    end
   end
 
   def test_lgamma