[src/set_{si,ui}_2exp.c] Bug fix in MPFR_LONG_WITHIN_LIMB defined case:

added early underflow/overflow checking to avoid integer overflow or
errors due to special exponent values.

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@13809 280ebfd0-de03-0410-8827-d642c229c3f4

2 files changed, 18 insertions, 0 deletions

diff --git a/src/set_si_2exp.c b/src/set_si_2exp.c
index f67f84b3e..5e703a47a 100644
--- a/src/set_si_2exp.c
+++ b/src/set_si_2exp.c
@@ -41,6 +41,15 @@ mpfr_set_si_2exp (mpfr_ptr x, long i, mpfr_exp_t e, mpfr_rnd_t rnd_mode)
       mp_limb_t ai, *xp;
       int inex = 0;
 
+      /* Early underflow/overflow checking is necessary to avoid
+         integer overflow or errors due to special exponent values. */
+      if (MPFR_UNLIKELY (e < __gmpfr_emin - (mpfr_exp_t)
+                         (sizeof (unsigned long) * CHAR_BIT + 1)))
+        return mpfr_underflow (x, rnd_mode == MPFR_RNDN ?
+                               MPFR_RNDZ : rnd_mode, i < 0 ? -1 : 1);
+      if (MPFR_UNLIKELY (e >= __gmpfr_emax))
+        return mpfr_overflow (x, rnd_mode, i < 0 ? -1 : 1);
+
       ai = SAFE_ABS (unsigned long, i);
       MPFR_ASSERTN (SAFE_ABS (unsigned long, i) == ai);
 
diff --git a/src/set_ui_2exp.c b/src/set_ui_2exp.c
index a0c61068a..fa72613ab 100644
--- a/src/set_ui_2exp.c
+++ b/src/set_ui_2exp.c
@@ -42,6 +42,15 @@ mpfr_set_ui_2exp (mpfr_ptr x, unsigned long i, mpfr_exp_t e, mpfr_rnd_t rnd_mode
       mp_limb_t *xp;
       int inex = 0;
 
+      /* Early underflow/overflow checking is necessary to avoid
+         integer overflow or errors due to special exponent values. */
+      if (MPFR_UNLIKELY (e < __gmpfr_emin - (mpfr_exp_t)
+                         (sizeof (unsigned long) * CHAR_BIT + 1)))
+        return mpfr_underflow (x, rnd_mode == MPFR_RNDN ?
+                               MPFR_RNDZ : rnd_mode, i < 0 ? -1 : 1);
+      if (MPFR_UNLIKELY (e >= __gmpfr_emax))
+        return mpfr_overflow (x, rnd_mode, i < 0 ? -1 : 1);
+
       MPFR_ASSERTD (i == (mp_limb_t) i);
 
       /* Position of the highest limb */