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x86: fix Autoconf caching of instruction support checks [BZ #27991]

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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.

Signed-off-by: Matt Whitlock <sourceware@mattwhitlock.name>
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
This commit is contained in:
Matt Whitlock 2021-06-16 23:40:47 -04:00 committed by Adhemerval Zanella
parent bca0f5cbc9
commit 0835c0f0ba
2 changed files with 56 additions and 40 deletions
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62
sysdeps/x86/configure vendored
View File

@ -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"

34
sysdeps/x86/configure.ac
View File

@ -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])