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Re: [PATCH RFC] X86_64 Avx2 Detection
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Ling Ma <ling dot ma dot program at gmail dot com>
- Cc: GNU C Library <libc-alpha at sourceware dot org>, Ondrej Bilka <neleai at seznam dot cz>, Andreas Jaeger <aj at suse dot com>, Liubov Dmitrieva <liubov dot dmitrieva at gmail dot com>, Sihai Yao <sihai dot ysh at alibaba-inc dot com>
- Date: Mon, 14 Apr 2014 08:15:50 -0700
- Subject: Re: [PATCH RFC] X86_64 Avx2 Detection
- Authentication-results: sourceware.org; auth=none
- References: <1397480031-5847-1-git-send-email-sihai dot ysh at alibaba-inc dot com>
On Mon, Apr 14, 2014 at 5:53 AM, <ling.ma.program@gmail.com> wrote:
> From: Sihai Yao <sihai.ysh@alibaba-inc.com>
>
> This patch sets bit_AVX2_Usable of __cpu_features.feature by checking
> COMMON_CPUID_INDEX_7 for Haswell. Architecture related assembler file
> can use this bit to determine calling path.
>
> ---
> This version removed the unrelated cpu module branch code and FEATURE_INDEX_7,
> which is unusefull for AVX
>
> ChangeLog | 8 ++++++++
> sysdeps/x86_64/multiarch/ifunc-defines.sym | 1 +
> sysdeps/x86_64/multiarch/init-arch.c | 3 +++
> sysdeps/x86_64/multiarch/init-arch.h | 8 ++++++++
> 4 files changed, 20 insertions(+)
>
> diff --git a/ChangeLog b/ChangeLog
> index fb0177d..ba8980c 100644
> --- a/ChangeLog
> +++ b/ChangeLog
> @@ -1,3 +1,11 @@
> +2014-04-04 Sihai Yao <sihai.ysh@alibaba-inc.com>
Need a blank line here.
> + * sysdeps/x86_64/multiarch/ifunc-defines.sym: Add COMMON_CPU_INDEX_7 and
> + FEATURE_INDEX_7.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ FEATURE_INDEX_7 has been removed.
> + * sysdeps/x86_64/multiarch/init-arch.c: Add AVX2 detection from cpu
> + features word of COMMON_CPUID_INDEX_7.
> + * sysdeps/x86_64/multiarch/init-arch.h: Add bit_AVX2_Usable and
> + index_AVX2_Usable for future assembly code to determing calling path.
> +
It looks good to me, except for ChangeLog.
> 2014-04-10 Torvald Riegel <triegel@redhat.com>
>
> * benchtests/pthread_once-inputs: New file.
> diff --git a/sysdeps/x86_64/multiarch/ifunc-defines.sym b/sysdeps/x86_64/multiarch/ifunc-defines.sym
> index eb1538a..a410d88 100644
> --- a/sysdeps/x86_64/multiarch/ifunc-defines.sym
> +++ b/sysdeps/x86_64/multiarch/ifunc-defines.sym
> @@ -17,4 +17,5 @@ FEATURE_OFFSET offsetof (struct cpu_features, feature)
> FEATURE_SIZE sizeof (unsigned int)
>
> COMMON_CPUID_INDEX_1
> +COMMON_CPUID_INDEX_7
> FEATURE_INDEX_1
> diff --git a/sysdeps/x86_64/multiarch/init-arch.c b/sysdeps/x86_64/multiarch/init-arch.c
> index db74d97..2a6dcb7 100644
> --- a/sysdeps/x86_64/multiarch/init-arch.c
> +++ b/sysdeps/x86_64/multiarch/init-arch.c
> @@ -167,6 +167,9 @@ __init_cpu_features (void)
> /* Determine if AVX is usable. */
> if (CPUID_AVX)
> __cpu_features.feature[index_AVX_Usable] |= bit_AVX_Usable;
> + /* Determine if AVX2 is usable. */
> + if (CPUID_AVX2)
> + __cpu_features.feature[index_AVX2_Usable] |= bit_AVX2_Usable;
> /* Determine if FMA is usable. */
> if (CPUID_FMA)
> __cpu_features.feature[index_FMA_Usable] |= bit_FMA_Usable;
> diff --git a/sysdeps/x86_64/multiarch/init-arch.h b/sysdeps/x86_64/multiarch/init-arch.h
> index 793707a..813b6de 100644
> --- a/sysdeps/x86_64/multiarch/init-arch.h
> +++ b/sysdeps/x86_64/multiarch/init-arch.h
> @@ -24,6 +24,7 @@
> #define bit_FMA_Usable (1 << 7)
> #define bit_FMA4_Usable (1 << 8)
> #define bit_Slow_SSE4_2 (1 << 9)
> +#define bit_AVX2_Usable (1 << 10)
>
> /* CPUID Feature flags. */
>
> @@ -40,6 +41,7 @@
>
> /* COMMON_CPUID_INDEX_7. */
> #define bit_RTM (1 << 11)
> +#define bit_AVX2 (1 << 5)
>
> /* XCR0 Feature flags. */
> #define bit_XMM_state (1 << 1)
> @@ -54,6 +56,7 @@
> # define index_SSE4_1 COMMON_CPUID_INDEX_1*CPUID_SIZE+CPUID_ECX_OFFSET
> # define index_SSE4_2 COMMON_CPUID_INDEX_1*CPUID_SIZE+CPUID_ECX_OFFSET
> # define index_AVX COMMON_CPUID_INDEX_1*CPUID_SIZE+CPUID_ECX_OFFSET
> +# define index_AVX2 COMMON_CPUID_INDEX_7*CPUID_SIZE+CPUID_EBX_OFFSET
>
> # define index_Fast_Rep_String FEATURE_INDEX_1*FEATURE_SIZE
> # define index_Fast_Copy_Backward FEATURE_INDEX_1*FEATURE_SIZE
> @@ -64,6 +67,7 @@
> # define index_FMA_Usable FEATURE_INDEX_1*FEATURE_SIZE
> # define index_FMA4_Usable FEATURE_INDEX_1*FEATURE_SIZE
> # define index_Slow_SSE4_2 FEATURE_INDEX_1*FEATURE_SIZE
> +# define index_AVX2_Usable FEATURE_INDEX_1*FEATURE_SIZE
>
> #else /* __ASSEMBLER__ */
>
> @@ -145,6 +149,8 @@ extern const struct cpu_features *__get_cpu_features (void)
> HAS_CPUID_FLAG (COMMON_CPUID_INDEX_80000001, ecx, bit_FMA4)
> # define CPUID_RTM \
> HAS_CPUID_FLAG (COMMON_CPUID_INDEX_7, ebx, bit_RTM)
> +# define CPUID_AVX2 \
> + HAS_CPUID_FLAG (COMMON_CPUID_INDEX_7, ebx, bit_AVX2)
>
> /* HAS_* evaluates to true if we may use the feature at runtime. */
> # define HAS_SSE2 HAS_CPU_FEATURE (COMMON_CPUID_INDEX_1, edx, bit_SSE2)
> @@ -153,6 +159,7 @@ extern const struct cpu_features *__get_cpu_features (void)
> # define HAS_SSE4_1 HAS_CPU_FEATURE (COMMON_CPUID_INDEX_1, ecx, bit_SSE4_1)
> # define HAS_SSE4_2 HAS_CPU_FEATURE (COMMON_CPUID_INDEX_1, ecx, bit_SSE4_2)
> # define HAS_RTM HAS_CPU_FEATURE (COMMON_CPUID_INDEX_7, ebx, bit_RTM)
> +# define HAS_AVX2 HAS_CPU_FEATURE (COMMON_CPUID_INDEX_7, ebx, bit_AVX2)
>
> # define index_Fast_Rep_String FEATURE_INDEX_1
> # define index_Fast_Copy_Backward FEATURE_INDEX_1
> @@ -163,6 +170,7 @@ extern const struct cpu_features *__get_cpu_features (void)
> # define index_FMA_Usable FEATURE_INDEX_1
> # define index_FMA4_Usable FEATURE_INDEX_1
> # define index_Slow_SSE4_2 FEATURE_INDEX_1
> +# define index_AVX2_Usable FEATURE_INDEX_1
>
> # define HAS_ARCH_FEATURE(name) \
> ((__get_cpu_features ()->feature[index_##name] & (bit_##name)) != 0)
> --
> 1.8.1.4
>
--
H.J.