illegal instruction on system without avx2 #203
Description
I'm trying to use python-blosc2 (2.6.2) on a system without avx2 but I'm getting an illegal instruction error on using avx2 instructions. The failed instruction disassembles as follows:
=> 0x00007f4773378934 <+212>: vinserti128 $0x1,%xmm1,%ymm0,%ymm0
As you can see below (using gcc 10, which appears to be the major version used to compile the binary), avx2 is not reported as available on the system.
> cat builtin.c
#include <stdio.h>
int main(void) {
__builtin_cpu_init();
printf("%d\n", __builtin_cpu_supports ("sse2"));
printf("%d\n", __builtin_cpu_supports ("avx"));
printf("%d\n", __builtin_cpu_supports ("avx2"));
printf("%d\n", __builtin_cpu_supports ("avx512bw"));
}
> /usr/bin/gcc-10 ./builtin.c; ./a.out
16
512
0
0
The c-blosc2 library I'm using is from the wheel and appears to be have been built with gcc 10.2.1:
strings -a lib/python3.12/site-packages/blosc2/blosc2_ext.cpython-312-x86_64-linux-gnu.so | grep GCC
GCC: (GNU) 10.2.1 20210130 (Red Hat 10.2.1-11)
My expectation is that the library would not use shuffle_axv2 based on the runtime flags, but for some reason we python-blosc2 is trying to use it anyway. Is there any other reason that we might still try to use this despite the values from __builtin_cpu_supports? Thanks.