ni...@lysator.liu.se (Niels Möller) writes:
> There are a couple of other uses of LOCAL_SHIFT_BITS,
> LOCAL_GMP_LIMB_BITS, LOCAL_CHAR_BIT, added as part of the support for
> testing with small limb sizes. Is it for some reason important to refer
> to these constants via int variables? They all look a bit odd to me.
Now I've tried changing it, and it seems to also be a hack to avoid
warnings?
In this macro,
#define gmp_umul_ppmm(w1, w0, u, v) \
do { \
int LOCAL_GMP_LIMB_BITS = GMP_LIMB_BITS; \
if (sizeof(unsigned int) * CHAR_BIT >= 2 * GMP_LIMB_BITS) \
{ \
unsigned int __ww = (unsigned int) (u) * (v); \
w0 = (mp_limb_t) __ww; \
w1 = (mp_limb_t) (__ww >> LOCAL_GMP_LIMB_BITS); \
} \
if I change the shift to
w1 = (mp_limb_t) (__ww >> GMP_LIMB_BITS); \
I get another warning,
gcc -O2 -pedantic -fomit-frame-pointer -m64 -mtune=broadwell -march=broadwell
-I../.. -c /home/nisse/hack/gmp/mini-gmp/tests/testutils.c -o testutils.o
In file included from
/home/nisse/hack/gmp/mini-gmp/tests/testutils.c:24:
/home/nisse/hack/gmp/mini-gmp/tests/../mini-gmp.c: In function ‘mpn_mul_1’:
/home/nisse/hack/gmp/mini-gmp/tests/../mini-gmp.c:137:25: warning: right shift
count >= width of type [-Wshift-count-overflow]
w1 = (mp_limb_t) (__ww >> GMP_LIMB_BITS); \
^~
This is with gcc-8.3. I don't think it's reasonable for the compiler to
complain about this, when the code is not reachable. Maybe I should
install gcc-9 (or even gcc-10) and see if it behaves differently.
Regards,
/Niels
--
Niels Möller. PGP-encrypted email is preferred. Keyid 368C6677.
Internet email is subject to wholesale government surveillance.
_______________________________________________
gmp-devel mailing list
gmp-devel@gmplib.org
https://gmplib.org/mailman/listinfo/gmp-devel
