[v14,1/2] x86: Add defines / utilities for making ISA specific x86 builds

1. Factor out some of the ISA level defines in isa-level.c to
   standalone header isa-level.h

2. Add new headers with ISA level dependent macros for handling
   ifuncs.

Note, this file does not change any code.

Tested with and without multiarch on x86_64 for ISA levels:
{generic, x86-64-v2, x86-64-v3, x86-64-v4}

And m32 with and without multiarch.
---
 sysdeps/x86/init-arch.h           |   4 +-
 sysdeps/x86/isa-ifunc-macros.h    |  70 ++++++++++++++++++++
 sysdeps/x86/isa-level.c           |  17 ++---
 sysdeps/x86/isa-level.h           | 102 ++++++++++++++++++++++++++++++
 sysdeps/x86_64/isa-default-impl.h |  49 ++++++++++++++
 5 files changed, 229 insertions(+), 13 deletions(-)
 create mode 100644 sysdeps/x86/isa-ifunc-macros.h
 create mode 100644 sysdeps/x86/isa-level.h
 create mode 100644 sysdeps/x86_64/isa-default-impl.h

On Wed, Jun 22, 2022 at 4:51 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
>
> 1. Factor out some of the ISA level defines in isa-level.c to
>    standalone header isa-level.h
>
> 2. Add new headers with ISA level dependent macros for handling
>    ifuncs.
>
> Note, this file does not change any code.
>
> Tested with and without multiarch on x86_64 for ISA levels:
> {generic, x86-64-v2, x86-64-v3, x86-64-v4}
>
> And m32 with and without multiarch.
> ---
>  sysdeps/x86/init-arch.h           |   4 +-
>  sysdeps/x86/isa-ifunc-macros.h    |  70 ++++++++++++++++++++
>  sysdeps/x86/isa-level.c           |  17 ++---
>  sysdeps/x86/isa-level.h           | 102 ++++++++++++++++++++++++++++++
>  sysdeps/x86_64/isa-default-impl.h |  49 ++++++++++++++
>  5 files changed, 229 insertions(+), 13 deletions(-)
>  create mode 100644 sysdeps/x86/isa-ifunc-macros.h
>  create mode 100644 sysdeps/x86/isa-level.h
>  create mode 100644 sysdeps/x86_64/isa-default-impl.h
>
> diff --git a/sysdeps/x86/init-arch.h b/sysdeps/x86/init-arch.h
> index 277c15f116..a2886a2532 100644
> --- a/sysdeps/x86/init-arch.h
> +++ b/sysdeps/x86/init-arch.h
> @@ -19,7 +19,9 @@
>  #include <ifunc-init.h>
>  #include <isa.h>
>
> -#ifndef __x86_64__
> +#ifdef __x86_64__
> +# include <isa-ifunc-macros.h>
> +#else
>  /* Due to the reordering and the other nifty extensions in i686, it is
>     not really good to use heavily i586 optimized code on an i686.  It's
>     better to use i486 code if it isn't an i586.  */
> diff --git a/sysdeps/x86/isa-ifunc-macros.h b/sysdeps/x86/isa-ifunc-macros.h
> new file mode 100644
> index 0000000000..ba6826d518
> --- /dev/null
> +++ b/sysdeps/x86/isa-ifunc-macros.h
> @@ -0,0 +1,70 @@
> +/* Common ifunc selection utils
> +   All versions must be listed in ifunc-impl-list.c.
> +   Copyright (C) 2022 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/>.  */
> +
> +#ifndef _ISA_IFUNC_MACROS_H
> +#define _ISA_IFUNC_MACROS_H 1
> +
> +#include <isa-level.h>
> +#include <sys/cdefs.h>
> +#include <stdlib.h>
> +
> +/* Only include at the level of the minimum build ISA or higher. I.e
> +   if built with ISA=V1, then include all implementations. On the
> +   other hand if built with ISA=V3 only include V3/V4
> +   implementations. If there is no implementation at or above the
> +   minimum build ISA level, then include the highest ISA level
> +   implementation.  */
> +#if MINIMUM_X86_ISA_LEVEL <= 4
> +# define X86_IFUNC_IMPL_ADD_V4(...) IFUNC_IMPL_ADD (__VA_ARGS__)
> +#endif
> +#if MINIMUM_X86_ISA_LEVEL <= 3
> +# define X86_IFUNC_IMPL_ADD_V3(...) IFUNC_IMPL_ADD (__VA_ARGS__)
> +#endif
> +#if MINIMUM_X86_ISA_LEVEL <= 2
> +# define X86_IFUNC_IMPL_ADD_V2(...) IFUNC_IMPL_ADD (__VA_ARGS__)
> +#endif
> +#if MINIMUM_X86_ISA_LEVEL <= 1
> +# define X86_IFUNC_IMPL_ADD_V1(...) IFUNC_IMPL_ADD (__VA_ARGS__)
> +#endif
> +
> +#ifndef X86_IFUNC_IMPL_ADD_V4
> +# define X86_IFUNC_IMPL_ADD_V4(...)
> +#endif
> +#ifndef X86_IFUNC_IMPL_ADD_V3
> +# define X86_IFUNC_IMPL_ADD_V3(...)
> +#endif
> +#ifndef X86_IFUNC_IMPL_ADD_V2
> +# define X86_IFUNC_IMPL_ADD_V2(...)
> +#endif
> +#ifndef X86_IFUNC_IMPL_ADD_V1
> +# define X86_IFUNC_IMPL_ADD_V1(...)
> +#endif
> +
> +#define X86_ISA_CPU_FEATURE_CONST_CHECK_ENABLED(name)                  \
> +  ((name##_X86_ISA_LEVEL) <= MINIMUM_X86_ISA_LEVEL)
> +
> +#define X86_ISA_CPU_FEATURE_USABLE_P(ptr, name)                        \
> +  (X86_ISA_CPU_FEATURE_CONST_CHECK_ENABLED (name)                      \
> +   || CPU_FEATURE_USABLE_P (ptr, name))
> +
> +#define X86_ISA_CPU_FEATURES_ARCH_P(ptr, name)                         \
> +  (X86_ISA_CPU_FEATURE_CONST_CHECK_ENABLED (name)                      \
> +   || CPU_FEATURES_ARCH_P (ptr, name))
> +
> +#endif
> diff --git a/sysdeps/x86/isa-level.c b/sysdeps/x86/isa-level.c
> index 09cd72ab20..5b7a2da870 100644
> --- a/sysdeps/x86/isa-level.c
> +++ b/sysdeps/x86/isa-level.c
> @@ -26,38 +26,31 @@
>     <https://www.gnu.org/licenses/>.  */
>
>  #include <elf.h>
> -
> +#include <sysdeps/x86/isa-level.h>
>  /* ELF program property for x86 ISA level.  */
>  #ifdef INCLUDE_X86_ISA_LEVEL
> -# if defined __SSE__ && defined __SSE2__
> +# if MINIMUM_X86_ISA_LEVEL >= 1
>  /* NB: ISAs, excluding MMX, in x86-64 ISA level baseline are used.  */
>  #  define ISA_BASELINE GNU_PROPERTY_X86_ISA_1_BASELINE
>  # else
>  #  define ISA_BASELINE 0
>  # endif
>
> -# if ISA_BASELINE && defined __GCC_HAVE_SYNC_COMPARE_AND_SWAP_16 \
> -     && defined HAVE_X86_LAHF_SAHF && defined __POPCNT__ \
> -     && defined __SSE3__ && defined __SSSE3__ && defined __SSE4_1__ \
> -     && defined __SSE4_2__
> +# if MINIMUM_X86_ISA_LEVEL >= 2
>  /* NB: ISAs in x86-64 ISA level v2 are used.  */
>  #  define ISA_V2       GNU_PROPERTY_X86_ISA_1_V2
>  # else
>  #  define ISA_V2       0
>  # endif
>
> -# if ISA_V2 && defined __AVX__ && defined __AVX2__ && defined __F16C__ \
> -     && defined __FMA__ && defined __LZCNT__ && defined HAVE_X86_MOVBE \
> -     && defined __BMI__ && defined __BMI2__
> +# if MINIMUM_X86_ISA_LEVEL >= 3
>  /* NB: ISAs in x86-64 ISA level v3 are used.  */
>  #  define ISA_V3       GNU_PROPERTY_X86_ISA_1_V3
>  # else
>  #  define ISA_V3       0
>  # endif
>
> -# if ISA_V3 && defined __AVX512F__ && defined __AVX512BW__ \
> -     && defined __AVX512CD__ && defined __AVX512DQ__ \
> -     && defined __AVX512VL__
> +# if MINIMUM_X86_ISA_LEVEL >= 4
>  /* NB: ISAs in x86-64 ISA level v4 are used.  */
>  #  define ISA_V4       GNU_PROPERTY_X86_ISA_1_V4
>  # else
> diff --git a/sysdeps/x86/isa-level.h b/sysdeps/x86/isa-level.h
> new file mode 100644
> index 0000000000..7cae11c228
> --- /dev/null
> +++ b/sysdeps/x86/isa-level.h
> @@ -0,0 +1,102 @@
> +/* Header defining the minimum x86 ISA level
> +   Copyright (C) 2022 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.
> +
> +   In addition to the permissions in the GNU Lesser General Public
> +   License, the Free Software Foundation gives you unlimited
> +   permission to link the compiled version of this file with other
> +   programs, and to distribute those programs without any restriction
> +   coming from the use of this file.  (The Lesser General Public
> +   License restrictions do apply in other respects; for example, they
> +   cover modification of the file, and distribution when not linked
> +   into another program.)
> +
> +   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/>.  */
> +
> +#ifndef _ISA_LEVEL_H
> +#define _ISA_LEVEL_H
> +
> +#if defined __SSE__ && defined __SSE2__
> +/* NB: ISAs, excluding MMX, in x86-64 ISA level baseline are used.  */
> +# define __X86_ISA_V1 1
> +#else
> +# define __X86_ISA_V1 0
> +#endif
> +
> +#if __X86_ISA_V1 && defined __GCC_HAVE_SYNC_COMPARE_AND_SWAP_16               \
> +    && defined HAVE_X86_LAHF_SAHF && defined __POPCNT__ && defined __SSE3__   \
> +    && defined __SSSE3__ && defined __SSE4_1__ && defined __SSE4_2__
> +/* NB: ISAs in x86-64 ISA level v2 are used.  */
> +# define __X86_ISA_V2 1
> +#else
> +# define __X86_ISA_V2 0
> +#endif
> +
> +#if __X86_ISA_V2 && defined __AVX__ && defined __AVX2__ && defined __F16C__   \
> +    && defined __FMA__ && defined __LZCNT__ && defined HAVE_X86_MOVBE         \
> +    && defined __BMI__ && defined __BMI2__
> +/* NB: ISAs in x86-64 ISA level v3 are used.  */
> +# define __X86_ISA_V3 1
> +#else
> +# define __X86_ISA_V3 0
> +#endif
> +
> +#if __X86_ISA_V3 && defined __AVX512F__ && defined __AVX512BW__               \
> +    && defined __AVX512CD__ && defined __AVX512DQ__ && defined __AVX512VL__
> +/* NB: ISAs in x86-64 ISA level v4 are used.  */
> +# define __X86_ISA_V4 1
> +#else
> +# define __X86_ISA_V4 0
> +#endif
> +
> +#define MINIMUM_X86_ISA_LEVEL                                                 \
> +  (__X86_ISA_V1 + __X86_ISA_V2 + __X86_ISA_V3 + __X86_ISA_V4)
> +
> +
> +/*
> + * CPU Features that are hard coded as enabled depending on ISA build
> + *   level.
> + *    - Values > 0 features are always ENABLED if:
> + *          Value >= MINIMUM_X86_ISA_LEVEL
> + */
> +
> +
> +/* ISA level >= 4 guaranteed includes.  */
> +#define AVX512VL_X86_ISA_LEVEL 4
> +#define AVX512BW_X86_ISA_LEVEL 4
> +
> +/* ISA level >= 3 guaranteed includes.  */
> +#define AVX2_X86_ISA_LEVEL 3
> +#define BMI2_X86_ISA_LEVEL 3
> +
> +/*
> + * NB: This may not be fully assumable for ISA level >= 3. From
> + * looking over the architectures supported in cpu-features.h the
> + * following CPUs may have an issue with this being default set:
> + *      - AMD Excavator
> + */
> +#define AVX_Fast_Unaligned_Load_X86_ISA_LEVEL 3
> +
> +/*
> + * KNL (the only cpu that sets this supported in cpu-features.h)
> + * builds with ISA V1 so this shouldn't harm any architectures.
> + */
> +#define Prefer_No_VZEROUPPER_X86_ISA_LEVEL 3
> +
> +#define ISA_SHOULD_BUILD(isa_build_level)                              \
> +  (MINIMUM_X86_ISA_LEVEL <= (isa_build_level) && IS_IN (libc))         \
> +   || defined ISA_DEFAULT_IMPL
> +
> +#endif
> diff --git a/sysdeps/x86_64/isa-default-impl.h b/sysdeps/x86_64/isa-default-impl.h
> new file mode 100644
> index 0000000000..34634668e5
> --- /dev/null
> +++ b/sysdeps/x86_64/isa-default-impl.h
> @@ -0,0 +1,49 @@
> +/* Utility for including proper default function based on ISA level
> +   Copyright (C) 2022 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/>.  */
> +
> +#include <isa-level.h>
> +
> +#ifndef DEFAULT_IMPL_V1
> +# error "Must have at least ISA V1 Version"
> +#endif
> +
> +#ifndef DEFAULT_IMPL_V2
> +# define DEFAULT_IMPL_V2 DEFAULT_IMPL_V1
> +#endif
> +
> +#ifndef DEFAULT_IMPL_V3
> +# define DEFAULT_IMPL_V3 DEFAULT_IMPL_V2
> +#endif
> +
> +#ifndef DEFAULT_IMPL_V4
> +# define DEFAULT_IMPL_V4 DEFAULT_IMPL_V3
> +#endif
> +
> +#if MINIMUM_X86_ISA_LEVEL == 1
> +# define ISA_DEFAULT_IMPL DEFAULT_IMPL_V1
> +#elif MINIMUM_X86_ISA_LEVEL == 2
> +# define ISA_DEFAULT_IMPL DEFAULT_IMPL_V2
> +#elif MINIMUM_X86_ISA_LEVEL == 3
> +# define ISA_DEFAULT_IMPL DEFAULT_IMPL_V3
> +#elif MINIMUM_X86_ISA_LEVEL == 4
> +# define ISA_DEFAULT_IMPL DEFAULT_IMPL_V4
> +#else
> +# error "Unsupported ISA Level!"
> +#endif
> +
> +#include ISA_DEFAULT_IMPL
> --
> 2.34.1
>

LGTM.

Thanks.