I tried to run the following program in my computer (Fedora 17 32bit). How can I enable my system to support the popcnt instruction for fast population count?
#include <stdio.h>
#include <nmmintrin.h>
int main(void)
{
int pop = _mm_popcnt_u32(0xf0f0f0f0ULL);
printf("pop = %d\n", pop);
return 0;
}
I compiled the program, and run it, but got the following exception:
[xiliu@xiliu tmp]$ gcc -Wall -march=corei7 -m32 -msse4.2 popcnt.c -o popcnt
[xiliu@xiliu tmp]$ ./popcnt
Illegal instruction (core dumped)
The following is the information of my processor:
[xiliu@xiliu tmp]$ cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 15
model name : Intel(R) Pentium(R) Dual CPU T2370 @ 1.73GHz
stepping : 13
microcode : 0xa4
cpu MHz : 800.000
cache size : 1024 KB
physical id : 0
siblings : 2
core id : 0
cpu cores : 2
apicid : 0
initial apicid : 0
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 10
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc arch_perfmon pebs bts aperfmperf pni dtes64 monitor ds_cpl est tm2 ssse3 cx16 xtpr pdcm lahf_lm dtherm
bogomips : 3458.20
clflush size : 64
cache_alignment : 64
address sizes : 36 bits physical, 48 bits virtual
power management:
[... repeated for 2nd core ...]
Use __builtin_popcount() instead, It isn't platform specific.