Avoid integer overflow in MPFR_FAST_COMPUTE_IF_SMALL_INPUT.

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@4468 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 2 insertions, 6 deletions

diff --git a/sin.c b/sin.c
index e44d215cb..90aa13c36 100644
--- a/sin.c
+++ b/sin.c
@@ -130,12 +130,8 @@ mpfr_sin (mpfr_ptr y, mpfr_srcptr x, mp_rnd_t rnd_mode)
     }
 
   /* sin(x) = x - x^3/6 + ... so the error is < 2^(3*EXP(x)-2) */
-  /* FIXME: we replaced -2*MPFR_GET_EXP (x)+2 by -2*MPFR_GET_EXP (x)+1,
-     which is still a valid bound, but looses one bit, to overcome the
-     problem when MPFR_GET_EXP(x)=-2^(w-2)+1 on a w-bit machine: then
-     -2*MPFR_GET_EXP (x)+2 = 2^(w-1) overflows. When this problem is
-     fixed in MPFR_FAST_COMPUTE_IF_SMALL_INPUT, replace 1 by 2. */
-  MPFR_FAST_COMPUTE_IF_SMALL_INPUT (y, x, -2*MPFR_GET_EXP (x)+1,0,rnd_mode,{});
+  MPFR_FAST_COMPUTE_IF_SMALL_INPUT (y, x, -2 * MPFR_GET_EXP (x), 2, 0,
+                                    rnd_mode, {});
 
   /* Compute initial precision */
   precy = MPFR_PREC (y);