tests/mpn/t-toom2-sqr.c: Define additional tests for the unlikely branch (cy<0)

1 files changed, 80 insertions, 0 deletions

diff --git a/tests/mpn/t-toom2-sqr.c b/tests/mpn/t-toom2-sqr.c
index a5cdcb577..1b428506e 100644
--- a/tests/mpn/t-toom2-sqr.c
+++ b/tests/mpn/t-toom2-sqr.c
@@ -3,4 +3,84 @@
 #define MIN_AN MPN_TOOM2_SQR_MINSIZE
 #define MAX_AN SQR_TOOM3_THRESHOLD
 
+#define MORE_SQR_TESTS explore_unlikely_branch
 #include "toom-sqr-shared.h"
+
+void
+explore_unlikely_branch (gmp_randstate_ptr rands)
+{
+  mp_ptr ap, refp, pp, scratch;
+  mp_size_t an;
+  mp_bitcnt_t bit;
+  TMP_DECL;
+  TMP_MARK;
+
+  ap = TMP_ALLOC_LIMBS (MAX_AN);
+  refp = TMP_ALLOC_LIMBS (MAX_AN * 2);
+  pp = 1 + TMP_ALLOC_LIMBS (MAX_AN * 2 + 2);
+  scratch
+    = 1+TMP_ALLOC_LIMBS (mpn_toomN_sqr_itch (MAX_AN) + 2);
+
+  for (an = MIN_AN + (MIN_AN & 1); an < MAX_AN; an+=2)
+    {
+      mp_size_t itch;
+      mp_limb_t p_before, p_after, s_before, s_after;
+
+      bit = an / 2 * GMP_NUMB_BITS
+	+ gmp_urandomm_ui (rands, an / 2 * GMP_NUMB_BITS - 1);
+
+      mpn_zero (ap, an);
+      mpn_zero (pp, an * 2);
+      pp [an - 1] |= GMP_NUMB_HIGHBIT;
+      pp [bit / GMP_NUMB_BITS] |= CNST_LIMB (1) << (bit % GMP_NUMB_BITS);
+      mpn_sqrtrem (ap, NULL, pp, an);
+      /* We need {ap, an} such that {ap + an/2, an/2} is zero and
+	 the result {pp, 2*an} is such that the sum
+	 {pp, an/2} + {pp + an/2, an/2} gives a carry. */
+      mpn_random2 (pp-1, an * 2 + 2);
+      p_before = pp[-1];
+      p_after = pp[an * 2];
+
+      itch = mpn_toomN_sqr_itch (an);
+      ASSERT_ALWAYS (itch <= mpn_toomN_sqr_itch (MAX_AN));
+      mpn_random2 (scratch-1, itch+2);
+      s_before = scratch[-1];
+      s_after = scratch[itch];
+
+      mpn_toomN_sqr (pp, ap, an, scratch);
+      refmpn_mul (refp, ap, an, ap, an);
+      if (pp[-1] != p_before || pp[an * 2] != p_after
+	  || scratch[-1] != s_before || scratch[itch] != s_after
+	  || mpn_cmp (refp, pp, an * 2) != 0)
+	{
+	  printf ("ERROR with bit %lu, an = %d\n",
+		  (unsigned long) bit, (int) an);
+	  if (pp[-1] != p_before)
+	    {
+	      printf ("before pp:"); mpn_dump (pp -1, 1);
+	      printf ("keep:   "); mpn_dump (&p_before, 1);
+	    }
+	  if (pp[an * 2] != p_after)
+	    {
+	      printf ("after pp:"); mpn_dump (pp + an * 2, 1);
+	      printf ("keep:   "); mpn_dump (&p_after, 1);
+	    }
+	  if (scratch[-1] != s_before)
+	    {
+	      printf ("before scratch:"); mpn_dump (scratch-1, 1);
+	      printf ("keep:   "); mpn_dump (&s_before, 1);
+	    }
+	  if (scratch[itch] != s_after)
+	    {
+	      printf ("after scratch:"); mpn_dump (scratch + itch, 1);
+	      printf ("keep:   "); mpn_dump (&s_after, 1);
+	    }
+	  mpn_dump (ap, an);
+	  mpn_dump (pp, an * 2);
+	  mpn_dump (refp, an * 2);
+
+	  abort();
+	}
+    }
+  TMP_FREE;
+}