Hello mpir-devel,
I think I found a bug in MPIR 2.1.1 in mpz_divexact() (or I'm doing
something something very stupid). Running the following program gives a
Segmentation Fault:
#include <mpir.h>
int main()
{
mpz_t Z, R;
mpz_init(Z);
mpz_init(R);
mpz_ui_pow_ui(Z, 10, 100000);
mpz_divexact(R, Z, Z);
return 0;
}
gdb backtrace:
Program received signal SIGSEGV, Segmentation fault.
0x00007fa2f2b5245d in mpn_submul_1 () from
/usr/local/src/pari/local/lib/libmpir.so.8
(gdb) bt
#0 0x00007fa2f2b5245d in mpn_submul_1 () from
/usr/local/src/pari/local/lib/libmpir.so.8
#1 0x00007fa2f2b73e72 in __gmpn_sb_divappr_q () from
/usr/local/src/pari/local/lib/libmpir.so.8
#2 0x00007fa2f2b812f2 in __gmpn_inv_divappr_q () from
/usr/local/src/pari/local/lib/libmpir.so.8
#3 0x00007fa2f2b88765 in __gmpn_divexact () from
/usr/local/src/pari/local/lib/libmpir.so.8
#4 0x00007fa2f2b3fb4b in __gmpz_divexact () from
/usr/local/src/pari/local/lib/libmpir.so.8
#5 0x0000000000400741 in main () at mpirtest.c:8
My system is:
$ uname -a
Linux arcanis 2.6.32-gentoo-r7 #5 SMP Thu Jun 10 23:07:26 CEST 2010
x86_64 Intel(R) Core(TM)2 Duo CPU T5870 @ 2.00GHz GenuineIntel GNU/Linux
$ ./config.guess
core2-unknown-linux-gnu
$ gcc --version
gcc-4.4.3 (Gentoo 4.4.3-r2 p1.2) 4.4.3
This is with MPIR 2.1.1 configured with ./configure --enable-gmpcompat
This bug was found thanks to Sage (see
http://trac.sagemath.org/sage_trac/ticket/9837)
Jeroen Demeyer.
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