Original patch from: perfpow.c.diff

-= BEGIN original header =-

Copyright 1998, 1999, 2000, 2001, 2005, 2008 Free Software Foundation, Inc.

This file is part of the GNU MP Library.

The GNU MP Library is free software; you can redistribute it and/or modify

it under the terms of the GNU Lesser 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 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 Lesser General Public

License for more details.

You should have received a copy of the GNU Lesser General Public License

along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.

-= END original header =-

diff -durN gmp-4.2.4.orig/mpz/perfpow.c gmp-4.2.4/mpz/perfpow.c

--- gmp-4.2.4.orig/mpz/perfpow.c	2007-08-30 20:31:41.000000000 +0200

+++ gmp-4.2.4/mpz/perfpow.c	2009-03-08 18:36:16.000000000 +0100

@@ -1,7 +1,7 @@

 /* mpz_perfect_power_p(arg) -- Return non-zero if ARG is a perfect power,

    zero otherwise.

-Copyright 1998, 1999, 2000, 2001, 2005 Free Software Foundation, Inc.

+Copyright 1998, 1999, 2000, 2001, 2005, 2008 Free Software Foundation, Inc.

 This file is part of the GNU MP Library.

@@ -59,6 +59,8 @@

 #define SMALLEST_OMITTED_PRIME 1009

+#define POW2P(a) (((a) & ((a) - 1)) == 0)

+

 int

 mpz_perfect_power_p (mpz_srcptr u)

 {

@@ -72,16 +74,13 @@

   mp_size_t usize = SIZ (u);

   TMP_DECL;

-  if (usize == 0)

-    return 1;			/* consider 0 a perfect power */

+  if (mpz_cmpabs_ui (u, 1) <= 0)

+    return 1;			/* -1, 0, and +1 are perfect powers */

   n2 = mpz_scan1 (u, 0);

   if (n2 == 1)

     return 0;			/* 2 divides exactly once.  */

-  if (n2 != 0 && (n2 & 1) == 0 && usize < 0)

-    return 0;			/* 2 has even multiplicity with negative U */

-

   TMP_MARK;

   uns = ABS (usize) - n2 / BITS_PER_MP_LIMB;

@@ -89,6 +88,14 @@

   MPZ_TMP_INIT (u2, uns);

   mpz_tdiv_q_2exp (u2, u, n2);

+  mpz_abs (u2, u2);

+

+  if (mpz_cmp_ui (u2, 1) == 0)

+    {

+      TMP_FREE;

+      /* factoring completed; consistent power */

+      return ! (usize < 0 && POW2P(n2));

+    }

   if (isprime (n2))

     goto n2prime;

@@ -97,6 +104,9 @@

     {

       prime = primes[i];

+      if (mpz_cmp_ui (u2, prime) < 0)

+	break;

+

       if (mpz_divisible_ui_p (u2, prime))	/* divisible by this prime? */

 	{

 	  rem = mpz_tdiv_q_ui (q, u2, prime * prime);

@@ -115,12 +125,6 @@

 	      n++;

 	    }

-	  if ((n & 1) == 0 && usize < 0)

-	    {

-	      TMP_FREE;

-	      return 0;		/* even multiplicity with negative U, reject */

-	    }

-

 	  n2 = gcd (n2, n);

 	  if (n2 == 1)

 	    {

@@ -128,10 +132,11 @@

 	      return 0;		/* we have multiplicity 1 of some factor */

 	    }

-	  if (mpz_cmpabs_ui (u2, 1) == 0)

+	  if (mpz_cmp_ui (u2, 1) == 0)

 	    {

 	      TMP_FREE;

-	      return 1;		/* factoring completed; consistent power */

+	      /* factoring completed; consistent power */

+	      return ! (usize < 0 && POW2P(n2));

 	    }

 	  /* As soon as n2 becomes a prime number, stop factoring.

@@ -169,6 +174,10 @@

   else

     {

       unsigned long int nth;

+

+      if (usize < 0 && POW2P(n2))

+	return 0;

+

       /* We found some factors above.  We just need to consider values of n

 	 that divides n2.  */

       for (nth = 2; nth <= n2; nth++)

@@ -184,8 +193,11 @@

 	    exact = mpz_root (q, u2, nth);

 	  if (exact)

 	    {

-	      TMP_FREE;

-	      return 1;

+	      if (! (usize < 0 && POW2P(nth)))

+		{

+		  TMP_FREE;

+		  return 1;

+		}

 	    }

 	  if (mpz_cmp_ui (q, SMALLEST_OMITTED_PRIME) < 0)

 	    {

@@ -199,6 +211,9 @@

     }

 n2prime:

+  if (usize < 0 && POW2P(n2))

+    return 0;

+

   exact = mpz_root (NULL, u2, n2);

   TMP_FREE;

   return exact;