Problem with gmp 4.2.2 and GCC 4.3.2 and 4.3.3

Jean Christophe Beyler jean.christophe.beyler at
Thu Dec 17 23:12:27 CET 2009

Dear all,

Here is the following test program:

#include <stdio.h>
#include <gmp.h>

int main() {
    mpz_t a,b;
    mpz_init_set_str(a, "10000000000", 10); // program works with 10^9, but not
    // with 10^10 (10^20 > 2^64)
    mpz_init_set(b, a);
    mpz_mul(a, a, a);
    gmp_printf("first,  in GMP mpz_mul(a,a,a) with a=%Zd gives %Zd \n", b, a);
    mpz_set(b, a);
    mpz_mul(a, a, a);
    gmp_printf("second, in GMP mpz_mul(a,a,a) with a=%Zd gives %Zd \n", b, a);
    return 0;

which outputs:
first,  in GMP mpz_mul(a,a,a) with a=10000000000 gives 100000000000000000000
second, in GMP mpz_mul(a,a,a) with a=100000000000000000000 gives

Clearly the second is result is wrong.

- I am using GMP 4.2.2
- First, I had my port on 4.3.2 but moved it to 4.3.3 because of the
line on your webpage stating :
N.B. gcc 4.3.2 miscompiles GMP 4.3.x on 64-bit machines. The problem
is specific to that very release; specifically gcc 4.3.1 and 4.3.3
seem to work fine.

However, it seems that we have a problem with 4.3.3 as well.

Gcc version:
Using built-in specs.
Target: myarch64-linux-elf
Configured with:
--prefix=/home/beyler/myarch64/local --disable-nls
--enable-languages=c --with-newlib --disable-libssp
Thread model: single
gcc version 4.3.3 (GCC)

GMP version is 4.2.2

Thanks for any help,
Jean Christophe Beyler

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