From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: Matt Whitlock <sourceware@mattwhitlock.name>, libc-alpha@sourceware.org
Subject: Re: [PATCH] x86: fix Autoconf caching of instruction support checks [BZ #27991]
Date: Wed, 11 Aug 2021 13:44:09 -0300 [thread overview]
Message-ID: <fa1d55fb-889d-fda8-ad17-adf9250a0db4@linaro.org> (raw)
In-Reply-To: <20210617034047.25355-1-sourceware@mattwhitlock.name>
On 17/06/2021 00:40, Matt Whitlock wrote:
> The Autoconf documentation for the AC_CACHE_CHECK macro states:
>
> The commands-to-set-it must have no side effects except for setting
> the variable cache-id, see below.
>
> However, the tests for support of -msahf and -mmovbe were embedded in
> the commands-to-set-it for lib_cv_include_x86_isa_level. This had the
> consequence that libc_cv_have_x86_lahf_sahf and libc_cv_have_x86_movbe
> were not defined whenever lib_cv_include_x86_isa_level was read from
> cache. These variables' being undefined meant that their unquoted use
> in later test expressions led to the 'test' built-in's misparsing its
> arguments and emitting errors like "test: =: unexpected operator" or
> "test: =: unary operator expected", depending on the particular shell.
>
> This commit refactors the tests for LAHF/SAHF and MOVBE instruction
> support into their own AC_CACHE_CHECK macro invocations to obey the
> rule that the commands-to-set-it must have no side effects other than
> setting the variable named by cache-id.
LGTM, thanks. Also, please confirm that you're the original author and
are authorized to contribute this patch by adding either a DCO, i.e. add a
Signed-off-by to indicate that; or by copyright assignment to the FSF
(check 2.1 and 2.2 on the Contribution Checklist [1])
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
[1] https://sourceware.org/glibc/wiki/Contribution%20checklist
> ---
> sysdeps/x86/configure | 62 ++++++++++++++++++++++++----------------
> sysdeps/x86/configure.ac | 34 +++++++++++-----------
> 2 files changed, 56 insertions(+), 40 deletions(-)
>
> diff --git a/sysdeps/x86/configure b/sysdeps/x86/configure
> index ead1295c38..62676bb686 100644
> --- a/sysdeps/x86/configure
> +++ b/sysdeps/x86/configure
> @@ -126,8 +126,6 @@ cat > conftest2.S <<EOF
> 4:
> EOF
> libc_cv_include_x86_isa_level=no
> -libc_cv_have_x86_lahf_sahf=no
> -libc_cv_have_x86_movbe=no
> if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS -nostartfiles -nostdlib -r -o conftest conftest1.S conftest2.S'
> { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
> (eval $ac_try) 2>&5
> @@ -137,24 +135,6 @@ if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS -nostartfiles -nostdlib -r -o conftest c
> count=`LC_ALL=C $READELF -n conftest | grep NT_GNU_PROPERTY_TYPE_0 | wc -l`
> if test "$count" = 1; then
> libc_cv_include_x86_isa_level=yes
> - cat > conftest.c <<EOF
> -EOF
> - if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS -fverbose-asm -S -o - conftest.c'
> - { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
> - (eval $ac_try) 2>&5
> - ac_status=$?
> - $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
> - test $ac_status = 0; }; } | grep -q "\-msahf"; then
> - libc_cv_have_x86_lahf_sahf=yes
> - fi
> - if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS -fverbose-asm -S -o - conftest.c'
> - { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
> - (eval $ac_try) 2>&5
> - ac_status=$?
> - $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
> - test $ac_status = 0; }; } | grep -q "\-mmovbe"; then
> - libc_cv_have_x86_movbe=yes
> - fi
> fi
> fi
> rm -f conftest*
> @@ -164,14 +144,48 @@ $as_echo "$libc_cv_include_x86_isa_level" >&6; }
> if test $libc_cv_include_x86_isa_level = yes; then
> $as_echo "#define INCLUDE_X86_ISA_LEVEL 1" >>confdefs.h
>
> + { $as_echo "$as_me:${as_lineno-$LINENO}: checking for LAHF/SAHF instruction support" >&5
> +$as_echo_n "checking for LAHF/SAHF instruction support... " >&6; }
> +if ${libc_cv_have_x86_lahf_sahf+:} false; then :
> + $as_echo_n "(cached) " >&6
> +else
> + libc_cv_have_x86_lahf_sahf=no
> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS -fverbose-asm -S -o - -x c /dev/null'
> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
> + (eval $ac_try) 2>&5
> + ac_status=$?
> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
> + test $ac_status = 0; }; } | grep -q "\-msahf"; then
> + libc_cv_have_x86_lahf_sahf=yes
> + fi
> fi
> -if test $libc_cv_have_x86_lahf_sahf = yes; then
> - $as_echo "#define HAVE_X86_LAHF_SAHF 1" >>confdefs.h
> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_have_x86_lahf_sahf" >&5
> +$as_echo "$libc_cv_have_x86_lahf_sahf" >&6; }
> + if test $libc_cv_have_x86_lahf_sahf = yes; then
> + $as_echo "#define HAVE_X86_LAHF_SAHF 1" >>confdefs.h
>
> + fi
> + { $as_echo "$as_me:${as_lineno-$LINENO}: checking for MOVBE instruction support" >&5
> +$as_echo_n "checking for MOVBE instruction support... " >&6; }
> +if ${libc_cv_have_x86_movbe+:} false; then :
> + $as_echo_n "(cached) " >&6
> +else
> + libc_cv_have_x86_movbe=no
> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS -fverbose-asm -S -o - -x c /dev/null'
> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
> + (eval $ac_try) 2>&5
> + ac_status=$?
> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
> + test $ac_status = 0; }; } | grep -q "\-mmovbe"; then
> + libc_cv_have_x86_movbe=yes
> + fi
> fi
> -if test $libc_cv_have_x86_movbe = yes; then
> - $as_echo "#define HAVE_X86_MOVBE 1" >>confdefs.h
> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_have_x86_movbe" >&5
> +$as_echo "$libc_cv_have_x86_movbe" >&6; }
> + if test $libc_cv_have_x86_movbe = yes; then
> + $as_echo "#define HAVE_X86_MOVBE 1" >>confdefs.h
>
> + fi
> fi
> config_vars="$config_vars
> enable-x86-isa-level = $libc_cv_include_x86_isa_level"
> diff --git a/sysdeps/x86/configure.ac b/sysdeps/x86/configure.ac
> index bca97fdc2f..04a12ab680 100644
> --- a/sysdeps/x86/configure.ac
> +++ b/sysdeps/x86/configure.ac
> @@ -98,30 +98,32 @@ cat > conftest2.S <<EOF
> 4:
> EOF
> libc_cv_include_x86_isa_level=no
> -libc_cv_have_x86_lahf_sahf=no
> -libc_cv_have_x86_movbe=no
> if AC_TRY_COMMAND(${CC-cc} $CFLAGS $CPPFLAGS -nostartfiles -nostdlib -r -o conftest conftest1.S conftest2.S); then
> count=`LC_ALL=C $READELF -n conftest | grep NT_GNU_PROPERTY_TYPE_0 | wc -l`
> if test "$count" = 1; then
> libc_cv_include_x86_isa_level=yes
> - cat > conftest.c <<EOF
> -EOF
> - if AC_TRY_COMMAND(${CC-cc} $CFLAGS $CPPFLAGS -fverbose-asm -S -o - conftest.c) | grep -q "\-msahf"; then
> - libc_cv_have_x86_lahf_sahf=yes
> - fi
> - if AC_TRY_COMMAND(${CC-cc} $CFLAGS $CPPFLAGS -fverbose-asm -S -o - conftest.c) | grep -q "\-mmovbe"; then
> - libc_cv_have_x86_movbe=yes
> - fi
> fi
> fi
> rm -f conftest*])
> if test $libc_cv_include_x86_isa_level = yes; then
> AC_DEFINE(INCLUDE_X86_ISA_LEVEL)
> -fi
> -if test $libc_cv_have_x86_lahf_sahf = yes; then
> - AC_DEFINE(HAVE_X86_LAHF_SAHF)
> -fi
> -if test $libc_cv_have_x86_movbe = yes; then
> - AC_DEFINE(HAVE_X86_MOVBE)
> + AC_CACHE_CHECK([for LAHF/SAHF instruction support],
> + libc_cv_have_x86_lahf_sahf, [dnl
> + libc_cv_have_x86_lahf_sahf=no
> + if AC_TRY_COMMAND(${CC-cc} $CFLAGS $CPPFLAGS -fverbose-asm -S -o - -x c /dev/null) | grep -q "\-msahf"; then
> + libc_cv_have_x86_lahf_sahf=yes
> + fi])
> + if test $libc_cv_have_x86_lahf_sahf = yes; then
> + AC_DEFINE(HAVE_X86_LAHF_SAHF)
> + fi
> + AC_CACHE_CHECK([for MOVBE instruction support],
> + libc_cv_have_x86_movbe, [dnl
> + libc_cv_have_x86_movbe=no
> + if AC_TRY_COMMAND(${CC-cc} $CFLAGS $CPPFLAGS -fverbose-asm -S -o - -x c /dev/null) | grep -q "\-mmovbe"; then
> + libc_cv_have_x86_movbe=yes
> + fi])
> + if test $libc_cv_have_x86_movbe = yes; then
> + AC_DEFINE(HAVE_X86_MOVBE)
> + fi
> fi
> LIBC_CONFIG_VAR([enable-x86-isa-level], [$libc_cv_include_x86_isa_level])
>
next prev parent reply other threads:[~2021-08-11 16:44 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-17 3:40 Matt Whitlock
2021-08-11 16:44 ` Adhemerval Zanella [this message]
2021-08-11 20:16 ` Matt Whitlock
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