speedup of mpfr_sub for same precision < GMP_NUMB_BITS

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@10539 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 45 insertions, 1 deletions

diff --git a/tests/tsub1sp.c b/tests/tsub1sp.c
index b191e350f..03c6723aa 100644
--- a/tests/tsub1sp.c
+++ b/tests/tsub1sp.c
@@ -24,6 +24,7 @@ http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
 
 static void check_special (void);
 static void check_random (mpfr_prec_t p);
+static void check_underflow (mpfr_prec_t p);
 
 int
 main (void)
@@ -32,6 +33,8 @@ main (void)
 
   tests_start_mpfr ();
 
+  for (p = MPFR_PREC_MIN; p < 200 ; p++)
+    check_underflow (p);
   check_special ();
   for (p = MPFR_PREC_MIN ; p < 200 ; p++)
     check_random (p);
@@ -49,7 +52,7 @@ main (void)
       printf ("Z="); mpfr_dump (z);                                     \
       printf ("Real: "); mpfr_dump (x2);                                \
       printf ("Got : "); mpfr_dump (x);                                 \
-      exit(1);                                                          \
+      abort();                                                          \
     }                                                                   \
  while (0)
 
@@ -509,3 +512,44 @@ check_special (void)
 
   mpfr_clears (x, y, z, x2, (mpfr_ptr) 0);
 }
+
+static void
+check_underflow (mpfr_prec_t p)
+{
+  mpfr_t x, y, z;
+  int inexact;
+
+  mpfr_inits2 (p, x, y, z, (mpfr_ptr) 0);
+
+  if (p >= 2) /* we need p >= 2 so that 3 is exact */
+    {
+      mpfr_set_ui_2exp (y, 4, mpfr_get_emin () - 2, MPFR_RNDN);
+      mpfr_set_ui_2exp (z, 3, mpfr_get_emin () - 2, MPFR_RNDN);
+      inexact = mpfr_sub (x, y, z, MPFR_RNDN);
+      if (inexact >= 0 || (mpfr_cmp_ui (x, 0) != 0))
+        {
+          printf ("4*2^(emin-2) - 3*2^(emin-2) with RNDN failed for p=%lu\n", p);
+          printf ("Expected inexact < 0 with x=0\n");
+          printf ("Got inexact=%d with x=");
+          mpfr_dump (x);
+          exit (1);
+        }
+    }
+
+  if (p >= 3) /* we need p >= 3 so that 5 is exact */
+    {
+      mpfr_set_ui_2exp (y, 5, mpfr_get_emin () - 2, MPFR_RNDN);
+      mpfr_set_ui_2exp (z, 4, mpfr_get_emin () - 2, MPFR_RNDN);
+      inexact = mpfr_sub (x, y, z, MPFR_RNDN);
+      if (inexact >= 0 || (mpfr_cmp_ui (x, 0) != 0))
+        {
+          printf ("5*2^(emin-2) - 4*2^(emin-2) with RNDN failed for p=%lu\n", p);
+          printf ("Expected inexact < 0 with x=0\n");
+          printf ("Got inexact=%d with x=");
+          mpfr_dump (x);
+          exit (1);
+        }
+    }
+
+  mpfr_clears (x, y, z, (mpfr_ptr) 0);
+}