[tests/tdiv.c] Added test case for a mpfr_div bug of MPFR 4.

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@12128 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 59 insertions, 0 deletions

diff --git a/tests/tdiv.c b/tests/tdiv.c
index 2ef925fda..02ffbec33 100644
--- a/tests/tdiv.c
+++ b/tests/tdiv.c
@@ -1519,11 +1519,70 @@ bug20171218 (void)
   mpfr_clear (c);
 }
 
+/* Extended test based on a bug found with flint-arb test suite with a
+   32-bit ABI: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=888459
+   A failure may occur in r12126 with pb=GMP_NUMB_BITS and MPFR_RNDN.
+*/
+static void
+bug20180126 (void)
+{
+  mpfr_t a, b1, b2, c1, c2;
+  int pa, i, j, pc, r, inex1, inex2;
+
+  for (pa = 100; pa < 800; pa += 11)
+    for (i = 1; i <= 4; i++)
+      for (j = -2; j <= 2; j++)
+        {
+          int pb = GMP_NUMB_BITS * i + j;
+
+          if (pb > pa)
+            continue;
+
+          mpfr_inits2 (pa, a, b1, (mpfr_ptr) 0);
+          mpfr_inits2 (pb, b2, (mpfr_ptr) 0);
+
+          mpfr_set_ui (a, 1, MPFR_RNDN);
+          mpfr_nextbelow (a);
+          mpfr_set_ui (b2, 1, MPFR_RNDN);
+          mpfr_nextbelow (b2);
+          inex1 = mpfr_set (b1, b2, MPFR_RNDN);
+          MPFR_ASSERTN (inex1 == 0);
+
+          for (pc = 32; pc <= 320; pc += 32)
+            {
+              mpfr_inits2 (pc, c1, c2, (mpfr_ptr) 0);
+
+              RND_LOOP_NO_RNDF (r)
+                {
+                  inex1 = mpfr_div (c1, a, b1, (mpfr_rnd_t) r);
+                  inex2 = mpfr_div (c2, a, b2, (mpfr_rnd_t) r);
+
+                  if (! mpfr_equal_p (c1, c2) || ! SAME_SIGN (inex1, inex2))
+                    {
+                      printf ("Error in bug20180126 for "
+                              "pa=%d pb=%d pc=%d %s\n", pa, pb, pc,
+                              mpfr_print_rnd_mode ((mpfr_rnd_t) r));
+                      printf ("inex1 = %d, c1 = ", inex1);
+                      mpfr_dump (c1);
+                      printf ("inex2 = %d, c2 = ", inex2);
+                      mpfr_dump (c2);
+                      exit (1);
+                    }
+                }
+
+              mpfr_clears (c1, c2, (mpfr_ptr) 0);
+            }
+
+          mpfr_clears (a, b1, b2, (mpfr_ptr) 0);
+        }
+}
+
 int
 main (int argc, char *argv[])
 {
   tests_start_mpfr ();
 
+  bug20180126 ();
   bug20171218 ();
   testall_rndf (9);
   test_20170105 ();