Avoid constant floating expression, as this doesn't give the correct

result with gcc on some Alpha machines. (patch by Paul Zimmermann)


git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@1906 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 7 insertions, 2 deletions

diff --git a/get_d.c b/get_d.c
index 46337a192..1eab9493a 100644
--- a/get_d.c
+++ b/get_d.c
@@ -116,13 +116,18 @@ mpfr_get_d3 (mpfr_srcptr src, mp_exp_t e, mp_rnd_t rnd_mode)
      subnormal is 2^(-1074)=0.1e-1073 */
   if (e < -1073)
     {
+      /* Note: Avoid using a constant expression DBL_MIN * DBL_EPSILON
+         as this gives 0 instead of the correct result with gcc on some
+         Alpha machines. */
       d = negative ?
         (rnd_mode == GMP_RNDD ||
          (rnd_mode == GMP_RNDN && mpfr_cmp_si_2exp(src, -1, -1075) < 0)
-         ? -DBL_MIN * DBL_EPSILON : -0.0) :
+         ? -DBL_MIN : -0.0) :
         (rnd_mode == GMP_RNDU ||
          (rnd_mode == GMP_RNDN && mpfr_cmp_si_2exp(src, 1, -1075) > 0)
-         ? DBL_MIN * DBL_EPSILON : 0.0);
+         ? DBL_MIN : 0.0);
+      if (d != 0.0)
+        d *= DBL_EPSILON;
     }
   /* the largest normalized number is 2^1024*(1-2^(-53))=0.111...111e1024 */
   else if (e > 1024)