crosstool-ng/patches/mpfr/3.1.3/150-divhigh-basecase.patch

diff -Naurd mpfr-3.1.3-a/PATCHES mpfr-3.1.3-b/PATCHES
--- mpfr-3.1.3-a/PATCHES	2015-10-29 13:47:46.735901185 +0000
+++ mpfr-3.1.3-b/PATCHES	2015-10-29 13:47:46.763900609 +0000
@@ -0,0 +1 @@
+divhigh-basecase
diff -Naurd mpfr-3.1.3-a/VERSION mpfr-3.1.3-b/VERSION
--- mpfr-3.1.3-a/VERSION	2015-07-17 08:58:21.118986898 +0000
+++ mpfr-3.1.3-b/VERSION	2015-10-29 13:47:46.763900609 +0000
@@ -1 +1 @@
-3.1.3-p4
+3.1.3-p5
diff -Naurd mpfr-3.1.3-a/src/mpfr.h mpfr-3.1.3-b/src/mpfr.h
--- mpfr-3.1.3-a/src/mpfr.h	2015-07-17 08:58:21.114986979 +0000
+++ mpfr-3.1.3-b/src/mpfr.h	2015-10-29 13:47:46.759900692 +0000
@@ -27,7 +27,7 @@
 #define MPFR_VERSION_MAJOR 3
 #define MPFR_VERSION_MINOR 1
 #define MPFR_VERSION_PATCHLEVEL 3
-#define MPFR_VERSION_STRING "3.1.3-p4"
+#define MPFR_VERSION_STRING "3.1.3-p5"
 
 /* Macros dealing with MPFR VERSION */
 #define MPFR_VERSION_NUM(a,b,c) (((a) << 16L) | ((b) << 8) | (c))
diff -Naurd mpfr-3.1.3-a/src/mulders.c mpfr-3.1.3-b/src/mulders.c
--- mpfr-3.1.3-a/src/mulders.c	2015-06-19 19:55:10.000000000 +0000
+++ mpfr-3.1.3-b/src/mulders.c	2015-10-29 13:47:46.751900855 +0000
@@ -236,9 +236,10 @@
          that in addition to the limb np[n-1] to reduce, we have at least 2
          extra limbs, thus accessing np[n-3] is valid. */
 
-      /* warning: we can have np[n-1]=d1 and np[n-2]=d0, but since {np,n} < D,
-         the largest possible partial quotient is B-1 */
-      if (MPFR_UNLIKELY(np[n - 1] == d1 && np[n - 2] == d0))
+      /* Warning: we can have np[n-1]>d1 or (np[n-1]=d1 and np[n-2]>=d0) here,
+         since we truncate the divisor at each step, but since {np,n} < D
+         originally, the largest possible partial quotient is B-1. */
+      if (MPFR_UNLIKELY(np[n-1] > d1 || (np[n-1] == d1 && np[n-2] >= d0)))
         q2 = ~ (mp_limb_t) 0;
       else
         udiv_qr_3by2 (q2, q1, q0, np[n - 1], np[n - 2], np[n - 3],
diff -Naurd mpfr-3.1.3-a/src/version.c mpfr-3.1.3-b/src/version.c
--- mpfr-3.1.3-a/src/version.c	2015-07-17 08:58:21.118986898 +0000
+++ mpfr-3.1.3-b/src/version.c	2015-10-29 13:47:46.763900609 +0000
@@ -25,5 +25,5 @@
 const char *
 mpfr_get_version (void)
 {
-  return "3.1.3-p4";
+  return "3.1.3-p5";
 }
diff -Naurd mpfr-3.1.3-a/tests/tdiv.c mpfr-3.1.3-b/tests/tdiv.c
--- mpfr-3.1.3-a/tests/tdiv.c	2015-06-19 19:55:10.000000000 +0000
+++ mpfr-3.1.3-b/tests/tdiv.c	2015-10-29 13:47:46.751900855 +0000
@@ -1099,6 +1099,69 @@
   mpfr_set_emax (old_emax);
 }
 
+/* Bug in mpfr_divhigh_n_basecase when all limbs of q (except the most
+   significant one) are B-1 where B=2^GMP_NUMB_BITS. Since we truncate
+   the divisor at each step, it might happen at some point that
+   (np[n-1],np[n-2]) > (d1,d0), and not only the equality.
+   Reported by Ricky Farr
+   <https://sympa.inria.fr/sympa/arc/mpfr/2015-10/msg00023.html>
+   To get a failure, a MPFR_DIVHIGH_TAB entry below the MPFR_DIV_THRESHOLD
+   limit must have a value 0. With most mparam.h files, this cannot occur. */
+static void
+test_20151023 (void)
+{
+  mpfr_prec_t p;
+  mpfr_t n, d, q, q0;
+  int inex, i;
+
+  for (p = GMP_NUMB_BITS; p <= 2000; p++)
+    {
+      mpfr_init2 (n, 2*p);
+      mpfr_init2 (d, p);
+      mpfr_init2 (q, p);
+      mpfr_init2 (q0, GMP_NUMB_BITS);
+
+      /* generate a random divisor of p bits */
+      mpfr_urandomb (d, RANDS);
+      /* generate a random quotient of GMP_NUMB_BITS bits */
+      mpfr_urandomb (q0, RANDS);
+      /* zero-pad the quotient to p bits */
+      inex = mpfr_prec_round (q0, p, MPFR_RNDN);
+      MPFR_ASSERTN(inex == 0);
+
+      for (i = 0; i < 3; i++)
+        {
+          /* i=0: try with the original quotient xxx000...000
+             i=1: try with the original quotient minus one ulp
+             i=2: try with the original quotient plus one ulp */
+          if (i == 1)
+            mpfr_nextbelow (q0);
+          else if (i == 2)
+            {
+              mpfr_nextabove (q0);
+              mpfr_nextabove (q0);
+            }
+
+          inex = mpfr_mul (n, d, q0, MPFR_RNDN);
+          MPFR_ASSERTN(inex == 0);
+          mpfr_nextabove (n);
+          mpfr_div (q, n, d, MPFR_RNDN);
+          MPFR_ASSERTN(mpfr_cmp (q, q0) == 0);
+
+          inex = mpfr_mul (n, d, q0, MPFR_RNDN);
+          MPFR_ASSERTN(inex == 0);
+          mpfr_nextbelow (n);
+          mpfr_div (q, n, d, MPFR_RNDN);
+          MPFR_ASSERTN(mpfr_cmp (q, q0) == 0);
+        }
+
+      mpfr_clear (n);
+      mpfr_clear (d);
+      mpfr_clear (q);
+      mpfr_clear (q0);
+    }
+}
+
 #define TEST_FUNCTION test_div
 #define TWO_ARGS
 #define RAND_FUNCTION(x) mpfr_random2(x, MPFR_LIMB_SIZE (x), randlimb () % 100, RANDS)
@@ -1219,6 +1282,7 @@
   consistency ();
   test_20070603 ();
   test_20070628 ();
+  test_20151023 ();
   test_generic (2, 800, 50);
   test_extreme ();