[Mesa-dev] [PATCH] mesa: Check return value of __get_cpuid().

[Brian Paul]

Reviewed-by: Brian Paul <brianp at vmware.com>

On 02/28/2015 11:09 AM, Matt Turner wrote:
> The use of the uninitialized_var() macro was to silence an uninitialized
> variable warning that I assumed stemmed from gcc being unable to see
> inside __get_cpuid() or understand its inline assembly.
>
> In fact, it was because the __get_cpuid() function can fail, and not
> initialize its arguments. Instead, check for failure and return early.
> ---
>   src/mesa/x86/common_x86.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/src/mesa/x86/common_x86.c b/src/mesa/x86/common_x86.c
> index 25f5c40..14b497d 100644
> --- a/src/mesa/x86/common_x86.c
> +++ b/src/mesa/x86/common_x86.c
> @@ -344,13 +344,13 @@ _mesa_get_x86_features(void)
>
>   #elif defined(USE_X86_64_ASM)
>      {
> -      unsigned int uninitialized_var(eax), uninitialized_var(ebx),
> -                   uninitialized_var(ecx), uninitialized_var(edx);
> +      unsigned int eax, ebx, ecx, edx;
>
>         /* Always available on x86-64. */
>         _mesa_x86_cpu_features |= X86_FEATURE_XMM | X86_FEATURE_XMM2;
>
> -      __get_cpuid(1, &eax, &ebx, &ecx, &edx);
> +      if (!__get_cpuid(1, &eax, &ebx, &ecx, &edx))
> +         return;
>
>         if (ecx & bit_SSE4_1)
>            _mesa_x86_cpu_features |= X86_FEATURE_SSE4_1;
>