Re: [Qemu-devel] [PATCH v3 7/9] cutils: Rewrite x86 buffer zero checking

[Paolo Bonzini]

On 13/09/2016 15:26, Paolo Bonzini wrote:
> I need this on top to fix compilation with older compilers:
> 
> diff --git a/util/bufferiszero.c b/util/bufferiszero.c
> index 3b39f82..1ce6b7a 100644
> --- a/util/bufferiszero.c
> +++ b/util/bufferiszero.c
> @@ -71,13 +71,13 @@ buffer_zero_int(const void *buf, size_t len)
> 
>  #if defined(CONFIG_AVX2_OPT) || defined(__SSE2__)
>  #include <cpuid.h>
> -#include <x86intrin.h>
> 
>  /* Note that we're going to check for LEN >= 64 for all of these.  */
> 
>  #ifdef CONFIG_AVX2_OPT
>  #pragma GCC push_options
>  #pragma GCC target("avx2")
> +#include <immintrin.h>
> 
>  static bool
>  buffer_zero_avx2(const void *buf, size_t len)
> @@ -181,6 +181,8 @@ buffer_zero_sse4(const void *buf, size_t len)
>  #pragma GCC target("sse2")
>  #endif /* CONFIG_AVX2_OPT */
> 
> +#include <emmintrin.h>
> +
>  static bool
>  buffer_zero_sse2(const void *buf, size_t len)
>  {
> 

Nope, not enough on GCC 4.8:

$ nm util/bufferiszero.o
0000000000000000 b buffer_accel
0000000000000430 T buffer_is_zero
0000000000000240 t buffer_zero_avx
0000000000000330 t buffer_zero_avx2
0000000000000000 t buffer_zero_int
00000000000000b0 t buffer_zero_sse2
0000000000000190 t buffer_zero_sse4
0000000000000008 b cpuid_cache
                 U _GLOBAL_OFFSET_TABLE_
0000000000000000 t init_cpuid_cache
                 U _mm_cmpeq_epi8
                 U _mm_loadu_si128
                 U _mm_movemask_epi8
                 U _mm_setzero_si128
                 U _mm_testz_si128
00000000000003d0 T test_buffer_is_zero_next_accel

Since I have no idea what's going on, I'm dropping these the last three
patches.

Paolo