[1/3] libcpp: configure: check for AVX2 instead of SSE4

  Upcoming patches first drop Binutils ISA support from SSE4.2 to SSSE3,
then bump it to AVX2. Instead of fiddling with detection, just bump
our configure check to AVX2 immediately: if by some accident somebody
builds GCC without AVX2 support in the assembler, they will get SSE2
vectorized lexer, which is not too slow.

libcpp/ChangeLog:

	* config.in: Regenerate.
	* configure: Regenerate.
	* configure.ac: Check for AVX2 instead of SSE4.2.
	* lex.cc: Adjust for changed config macro.
---
 libcpp/config.in    | 6 +++---
 libcpp/configure    | 4 ++--
 libcpp/configure.ac | 6 +++---
 libcpp/lex.cc       | 2 +-
 4 files changed, 9 insertions(+), 9 deletions(-)
  

On Tue, Aug 6, 2024 at 6:19 PM Alexander Monakov <amonakov@ispras.ru> wrote:
>
> Upcoming patches first drop Binutils ISA support from SSE4.2 to SSSE3,
> then bump it to AVX2. Instead of fiddling with detection, just bump
> our configure check to AVX2 immediately: if by some accident somebody
> builds GCC without AVX2 support in the assembler, they will get SSE2
> vectorized lexer, which is not too slow.

OK.

> libcpp/ChangeLog:
>
>         * config.in: Regenerate.
>         * configure: Regenerate.
>         * configure.ac: Check for AVX2 instead of SSE4.2.
>         * lex.cc: Adjust for changed config macro.
> ---
>  libcpp/config.in    | 6 +++---
>  libcpp/configure    | 4 ++--
>  libcpp/configure.ac | 6 +++---
>  libcpp/lex.cc       | 2 +-
>  4 files changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/libcpp/config.in b/libcpp/config.in
> index 253ef03a3d..a0ca9e4df4 100644
> --- a/libcpp/config.in
> +++ b/libcpp/config.in
> @@ -35,6 +35,9 @@
>     */
>  #undef HAVE_ALLOCA_H
>
> +/* Define to 1 if you can assemble AVX2 insns. */
> +#undef HAVE_AVX2
> +
>  /* Define to 1 if you have the Mac OS X function
>     CFLocaleCopyPreferredLanguages in the CoreFoundation framework. */
>  #undef HAVE_CFLOCALECOPYPREFERREDLANGUAGES
> @@ -210,9 +213,6 @@
>  /* Define to 1 if you have the `putc_unlocked' function. */
>  #undef HAVE_PUTC_UNLOCKED
>
> -/* Define to 1 if you can assemble SSE4 insns. */
> -#undef HAVE_SSE4
> -
>  /* Define to 1 if you have the <stddef.h> header file. */
>  #undef HAVE_STDDEF_H
>
> diff --git a/libcpp/configure b/libcpp/configure
> index 32d6aaa306..74af097620 100755
> --- a/libcpp/configure
> +++ b/libcpp/configure
> @@ -9140,14 +9140,14 @@ case $target in
>  int
>  main ()
>  {
> -asm ("pcmpestri %0, %%xmm0, %%xmm1" : : "i"(0))
> +asm ("vpshufb %ymm0, %ymm1, %ymm2")
>    ;
>    return 0;
>  }
>  _ACEOF
>  if ac_fn_c_try_compile "$LINENO"; then :
>
> -$as_echo "#define HAVE_SSE4 1" >>confdefs.h
> +$as_echo "#define HAVE_AVX2 1" >>confdefs.h
>
>  fi
>  rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
> diff --git a/libcpp/configure.ac b/libcpp/configure.ac
> index b883fec776..cfefb63552 100644
> --- a/libcpp/configure.ac
> +++ b/libcpp/configure.ac
> @@ -197,9 +197,9 @@ fi
>
>  case $target in
>    i?86-* | x86_64-*)
> -    AC_TRY_COMPILE([], [asm ("pcmpestri %0, %%xmm0, %%xmm1" : : "i"(0))],
> -      [AC_DEFINE([HAVE_SSE4], [1],
> -                [Define to 1 if you can assemble SSE4 insns.])])
> +    AC_TRY_COMPILE([], [asm ("vpshufb %ymm0, %ymm1, %ymm2")],
> +      [AC_DEFINE([HAVE_AVX2], [1],
> +                [Define to 1 if you can assemble AVX2 insns.])])
>  esac
>
>  # Enable --enable-host-shared.
> diff --git a/libcpp/lex.cc b/libcpp/lex.cc
> index 1591dcdf15..fa9c03614c 100644
> --- a/libcpp/lex.cc
> +++ b/libcpp/lex.cc
> @@ -344,7 +344,7 @@ search_line_sse2 (const uchar *s, const uchar *end ATTRIBUTE_UNUSED)
>    return (const uchar *)p + found;
>  }
>
> -#ifdef HAVE_SSE4
> +#ifdef HAVE_AVX2
>  /* A version of the fast scanner using SSE 4.2 vectorized string insns.  */
>
>  static const uchar *
> --
> 2.44.0
>