x86_simd_caps(void) {
unsigned int flags = 0;
unsigned int mask = ~0;
- unsigned int reg_eax, reg_ebx, reg_ecx, reg_edx;
+ unsigned int max_cpuid_val, reg_eax, reg_ebx, reg_ecx, reg_edx;
char *env;
(void)reg_ebx;
mask = strtol(env, NULL, 0);
/* Ensure that the CPUID instruction supports extended features */
- cpuid(0, 0, reg_eax, reg_ebx, reg_ecx, reg_edx);
+ cpuid(0, 0, max_cpuid_val, reg_ebx, reg_ecx, reg_edx);
- if (reg_eax < 1)
+ if (max_cpuid_val < 1)
return 0;
/* Get the standard feature flags */
if ((xgetbv() & 0x6) == 0x6) {
flags |= HAS_AVX;
- /* Get the leaf 7 feature flags. Needed to check for AVX2 support */
- cpuid(7, 0, reg_eax, reg_ebx, reg_ecx, reg_edx);
+ if (max_cpuid_val >= 7) {
+ /* Get the leaf 7 feature flags. Needed to check for AVX2 support */
+ cpuid(7, 0, reg_eax, reg_ebx, reg_ecx, reg_edx);
- if (reg_ebx & BIT(5)) flags |= HAS_AVX2;
+ if (reg_ebx & BIT(5)) flags |= HAS_AVX2;
+ }
}
}