[1/2] x86: Automate generation of PREFERRED_FEATURE_INDEX_1 bitfield

  Use a .def file to define the bitfield layout, so that it is possible
to iterate over field members using the preprocessor.

---
 .../cpu-features-preferred_feature_index_1.def     | 34 +++++++++++++++
 sysdeps/x86/include/cpu-features.h                 | 51 ++++++++--------------
 2 files changed, 51 insertions(+), 34 deletions(-)
  

On Tue, Mar 2, 2021 at 6:23 AM Florian Weimer <fweimer@redhat.com> wrote:
>
> Use a .def file to define the bitfield layout, so that it is possible
> to iterate over field members using the preprocessor.
>
> ---
>  .../cpu-features-preferred_feature_index_1.def     | 34 +++++++++++++++
>  sysdeps/x86/include/cpu-features.h                 | 51 ++++++++--------------
>  2 files changed, 51 insertions(+), 34 deletions(-)
>
> diff --git a/sysdeps/x86/include/cpu-features-preferred_feature_index_1.def b/sysdeps/x86/include/cpu-features-preferred_feature_index_1.def
> new file mode 100644
> index 0000000000..06af1a8dd5
> --- /dev/null
> +++ b/sysdeps/x86/include/cpu-features-preferred_feature_index_1.def
> @@ -0,0 +1,34 @@
> +/* Bits in the PREFERRED_FEATURE_INDEX_1 bitfield of <cpu-features.h>.
> +   Copyright (C) 2020-2021 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +BIT (Fast_Rep_String)
> +BIT (Fast_Copy_Backward)
> +BIT (Slow_BSF)
> +BIT (Fast_Unaligned_Load)
> +BIT (Prefer_PMINUB_for_stringop)
> +BIT (Fast_Unaligned_Copy)
> +BIT (I586)
> +BIT (I686)
> +BIT (Slow_SSE4_2)
> +BIT (AVX_Fast_Unaligned_Load)
> +BIT (Prefer_MAP_32BIT_EXEC)
> +BIT (Prefer_No_VZEROUPPER)
> +BIT (Prefer_ERMS)
> +BIT (Prefer_No_AVX512)
> +BIT (MathVec_Prefer_No_AVX512)
> +BIT (Prefer_FSRM)
> diff --git a/sysdeps/x86/include/cpu-features.h b/sysdeps/x86/include/cpu-features.h
> index ae5cb24be5..0fb988ead0 100644
> --- a/sysdeps/x86/include/cpu-features.h
> +++ b/sysdeps/x86/include/cpu-features.h
> @@ -772,40 +772,23 @@ enum
>  /* EBX.  */
>  #define reg_PTWRITE            ebx
>
> -/* PREFERRED_FEATURE_INDEX_1.  */
> -#define bit_arch_I586                          (1u << 0)
> -#define bit_arch_I686                          (1u << 1)
> -#define bit_arch_Fast_Rep_String               (1u << 2)
> -#define bit_arch_Fast_Copy_Backward            (1u << 3)
> -#define bit_arch_Fast_Unaligned_Load           (1u << 4)
> -#define bit_arch_Fast_Unaligned_Copy           (1u << 5)
> -#define bit_arch_Slow_BSF                      (1u << 6)
> -#define bit_arch_Slow_SSE4_2                   (1u << 7)
> -#define bit_arch_AVX_Fast_Unaligned_Load       (1u << 8)
> -#define bit_arch_Prefer_MAP_32BIT_EXEC         (1u << 9)
> -#define bit_arch_Prefer_PMINUB_for_stringop    (1u << 10)
> -#define bit_arch_Prefer_No_VZEROUPPER          (1u << 11)
> -#define bit_arch_Prefer_ERMS                   (1u << 12)
> -#define bit_arch_Prefer_FSRM                   (1u << 13)
> -#define bit_arch_Prefer_No_AVX512              (1u << 14)
> -#define bit_arch_MathVec_Prefer_No_AVX512      (1u << 15)
> -
> -#define index_arch_Fast_Rep_String             PREFERRED_FEATURE_INDEX_1
> -#define index_arch_Fast_Copy_Backward          PREFERRED_FEATURE_INDEX_1
> -#define index_arch_Slow_BSF                    PREFERRED_FEATURE_INDEX_1
> -#define index_arch_Fast_Unaligned_Load         PREFERRED_FEATURE_INDEX_1
> -#define index_arch_Prefer_PMINUB_for_stringop  PREFERRED_FEATURE_INDEX_1
> -#define index_arch_Fast_Unaligned_Copy         PREFERRED_FEATURE_INDEX_1
> -#define index_arch_I586                                PREFERRED_FEATURE_INDEX_1
> -#define index_arch_I686                                PREFERRED_FEATURE_INDEX_1
> -#define index_arch_Slow_SSE4_2                 PREFERRED_FEATURE_INDEX_1
> -#define index_arch_AVX_Fast_Unaligned_Load     PREFERRED_FEATURE_INDEX_1
> -#define index_arch_Prefer_MAP_32BIT_EXEC       PREFERRED_FEATURE_INDEX_1
> -#define index_arch_Prefer_No_VZEROUPPER                PREFERRED_FEATURE_INDEX_1
> -#define index_arch_Prefer_ERMS                 PREFERRED_FEATURE_INDEX_1
> -#define index_arch_Prefer_No_AVX512            PREFERRED_FEATURE_INDEX_1
> -#define index_arch_MathVec_Prefer_No_AVX512    PREFERRED_FEATURE_INDEX_1
> -#define index_arch_Prefer_FSRM                 PREFERRED_FEATURE_INDEX_1
> +/* PREFERRED_FEATURE_INDEX_1.  First define the bitindex values
> +   sequentially, then define the bit_arch* and index_arch_* lookup
> +   constants.  */
> +enum
> +  {
> +#define BIT(x) _bitindex_arch_##x ,
> +#include "cpu-features-preferred_feature_index_1.def"
> +#undef BIT
> +  };
> +enum
> +  {
> +#define BIT(x)                                 \
> +    bit_arch_##x = 1u << _bitindex_arch_##x ,  \
> +    index_arch_##x = PREFERRED_FEATURE_INDEX_1,
> +#include "cpu-features-preferred_feature_index_1.def"
> +#undef BIT
> +  };
>
>  /* XCR0 Feature flags.  */
>  #define bit_XMM_state          (1u << 1)
>

OK.

Thanks.