Add libgmp 6.2.0 to third_party

Don't build it yet.  That will come in the next review.

Change-Id: Idf3266558165e5ab45f4a41c98cc8c838c8244d5
diff --git a/third_party/gmp/tests/mpn/toom-shared.h b/third_party/gmp/tests/mpn/toom-shared.h
new file mode 100644
index 0000000..8188b00
--- /dev/null
+++ b/third_party/gmp/tests/mpn/toom-shared.h
@@ -0,0 +1,148 @@
+/* Test for various Toom functions.
+
+Copyright 2009 Free Software Foundation, Inc.
+
+This file is part of the GNU MP Library test suite.
+
+The GNU MP Library test suite is free software; you can redistribute it
+and/or modify it under the terms of the GNU General Public License as
+published by the Free Software Foundation; either version 3 of the License,
+or (at your option) any later version.
+
+The GNU MP Library test suite is distributed in the hope that it will be
+useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
+Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+the GNU MP Library test suite.  If not, see https://www.gnu.org/licenses/.  */
+
+
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "gmp-impl.h"
+#include "tests.h"
+
+/* Main file is expected to define mpn_toomMN_mul,
+ * mpn_toomMN_mul_itch, MIN_AN, MIN_BN(an), MAX_BN(an) and then
+ * include this file. */
+
+/* Sizes are up to 2^SIZE_LOG limbs */
+#ifndef SIZE_LOG
+#define SIZE_LOG 10
+#endif
+
+#ifndef COUNT
+#define COUNT 2000
+#endif
+
+#define MAX_AN (1L << SIZE_LOG)
+
+#ifndef MAX_BN
+#define MAX_BN(an) (an)
+#endif
+
+/* For general toomMN_mul, we need
+ *
+ * MIN_BN(an) = N + floor(((N-1)*an + M - N)/M)
+ *
+ * MAX_BN(an) = floor(N*(an-1)/(M-1)) - N + 1
+ */
+
+int
+main (int argc, char **argv)
+{
+  mp_ptr ap, bp, refp, pp, scratch;
+  int count = COUNT;
+  int test;
+  gmp_randstate_ptr rands;
+  TMP_DECL;
+  TMP_MARK;
+
+  TESTS_REPS (count, argv, argc);
+
+  tests_start ();
+  rands = RANDS;
+
+  ap = TMP_ALLOC_LIMBS (MAX_AN);
+  bp = TMP_ALLOC_LIMBS (MAX_BN(MAX_AN));
+  refp = TMP_ALLOC_LIMBS (MAX_AN + MAX_BN(MAX_AN));
+  pp = 1+TMP_ALLOC_LIMBS (MAX_AN + MAX_BN(MAX_AN)+2);
+  scratch
+    = 1+TMP_ALLOC_LIMBS (mpn_toomMN_mul_itch (MAX_AN, MAX_BN(MAX_AN))
+			 + 2);
+
+  for (test = 0; test < count; test++)
+    {
+      unsigned size_min;
+      unsigned size_range;
+      mp_size_t an, bn;
+      mp_size_t itch;
+      mp_limb_t p_before, p_after, s_before, s_after;
+
+      for (size_min = 1; (1L << size_min) < MIN_AN; size_min++)
+	;
+
+      /* We generate an in the MIN_AN <= an <= (1 << size_range). */
+      size_range = size_min
+	+ gmp_urandomm_ui (rands, SIZE_LOG + 1 - size_min);
+
+      an = MIN_AN
+	+ gmp_urandomm_ui (rands, (1L << size_range) + 1 - MIN_AN);
+      bn = MIN_BN(an)
+	+ gmp_urandomm_ui (rands, MAX_BN(an) + 1 - MIN_BN(an));
+
+      mpn_random2 (ap, an);
+      mpn_random2 (bp, bn);
+      mpn_random2 (pp-1, an + bn + 2);
+      p_before = pp[-1];
+      p_after = pp[an + bn];
+
+      itch = mpn_toomMN_mul_itch (an, bn);
+      ASSERT_ALWAYS (itch <= mpn_toomMN_mul_itch (MAX_AN, MAX_BN(MAX_AN)));
+      mpn_random2 (scratch-1, itch+2);
+      s_before = scratch[-1];
+      s_after = scratch[itch];
+
+      mpn_toomMN_mul (pp, ap, an, bp, bn, scratch);
+      refmpn_mul (refp, ap, an, bp, bn);
+      if (pp[-1] != p_before || pp[an + bn] != p_after
+	  || scratch[-1] != s_before || scratch[itch] != s_after
+	  || mpn_cmp (refp, pp, an + bn) != 0)
+	{
+	  printf ("ERROR in test %d, an = %d, bn = %d\n",
+		  test, (int) an, (int) bn);
+	  if (pp[-1] != p_before)
+	    {
+	      printf ("before pp:"); mpn_dump (pp -1, 1);
+	      printf ("keep:   "); mpn_dump (&p_before, 1);
+	    }
+	  if (pp[an + bn] != p_after)
+	    {
+	      printf ("after pp:"); mpn_dump (pp + an + bn, 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 (bp, bn);
+	  mpn_dump (pp, an + bn);
+	  mpn_dump (refp, an + bn);
+
+	  abort();
+	}
+    }
+  TMP_FREE;
+
+  tests_end ();
+  return 0;
+}