glibc/sysdeps/aarch64/configure.ac
Joe Ramsay cd94326a13 Enable libmvec support for AArch64
This patch enables libmvec on AArch64. The proposed change is mainly
implementing build infrastructure to add the new routines to ABI,
tests and benchmarks. I have demonstrated how this all fits together
by adding implementations for vector cos, in both single and double
precision, targeting both Advanced SIMD and SVE.

The implementations of the routines themselves are just loops over the
scalar routine from libm for now, as we are more concerned with
getting the plumbing right at this point. We plan to contribute vector
routines from the Arm Optimized Routines repo that are compliant with
requirements described in the libmvec wiki.

Building libmvec requires minimum GCC 10 for SVE ACLE. To avoid raising
the minimum GCC by such a big jump, we allow users to disable libmvec
if their compiler is too old.

Note that at this point users have to manually call the vector math
functions. This seems to be acceptable to some downstream users.

Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
2023-05-03 12:09:49 +01:00

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GLIBC_PROVIDES dnl See aclocal.m4 in the top level source directory.
# Local configure fragment for sysdeps/aarch64.
# Static PIE is supported.
AC_DEFINE(SUPPORT_STATIC_PIE)
# We check to see if the compiler and flags are
# selecting the big endian ABI and if they are then
# we set libc_cv_aarch64_be to yes which causes
# HAVE_AARCH64_BE to be defined in config.h and
# in include/libc-symbols.h and thus available to
# shlib-versions to select the appropriate name for
# the dynamic linker via %ifdef.
AC_CACHE_CHECK([for big endian],
[libc_cv_aarch64_be],
[AC_EGREP_CPP(yes,[#ifdef __AARCH64EB__
yes
#endif
], libc_cv_aarch64_be=yes, libc_cv_aarch64_be=no)])
if test $libc_cv_aarch64_be = yes; then
AC_DEFINE(HAVE_AARCH64_BE)
LIBC_CONFIG_VAR([default-abi], [lp64_be])
else
LIBC_CONFIG_VAR([default-abi], [lp64])
fi
# Only consider BTI supported if -mbranch-protection=bti is
# on by default in the compiler and the linker produces
# binaries with GNU property notes in PT_GNU_PROPERTY segment.
AC_CACHE_CHECK([for BTI support], [libc_cv_aarch64_bti], [dnl
cat > conftest.c <<EOF
void foo (void) { }
EOF
libc_cv_aarch64_bti=no
if AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS -nostdlib -nostartfiles $no_ssp -shared -fPIC -o conftest.so conftest.c]) \
&& AC_TRY_COMMAND([$READELF -lW conftest.so | grep -q GNU_PROPERTY]) \
&& AC_TRY_COMMAND([$READELF -nW conftest.so | grep -q "NT_GNU_PROPERTY_TYPE_0.*AArch64 feature:.* BTI"])
then
libc_cv_aarch64_bti=yes
fi
rm -rf conftest.*])
LIBC_CONFIG_VAR([aarch64-bti], [$libc_cv_aarch64_bti])
if test $libc_cv_aarch64_bti = yes; then
AC_DEFINE(HAVE_AARCH64_BTI)
fi
# Check if glibc is built with return address signing, i.e.
# if -mbranch-protection=pac-ret is on. We need this because
# pac-ret relies on unwinder support so it's not safe to use
# it in assembly code unconditionally, but there is no
# feature test macro for it in gcc.
AC_CACHE_CHECK([if pac-ret is enabled], [libc_cv_aarch64_pac_ret], [dnl
cat > conftest.c <<EOF
int bar (void);
int foo (void) { return bar () + 1; }
EOF
libc_cv_aarch64_pac_ret=no
if AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS -S -o conftest.s conftest.c]) \
&& AC_TRY_COMMAND([grep -q -E '\''(hint( | )+25|paciasp)'\'' conftest.s])
then
libc_cv_aarch64_pac_ret=yes
fi
rm -rf conftest.*])
if test $libc_cv_aarch64_pac_ret = yes; then
AC_DEFINE(HAVE_AARCH64_PAC_RET)
fi
# Check if binutils supports variant PCS symbols.
AC_CACHE_CHECK([for variant PCS support], [libc_cv_aarch64_variant_pcs], [dnl
cat > conftest.S <<EOF
.global foo
.type foo, %function
.variant_pcs foo
foo:
ret
.global bar
.type bar, %function
bar:
b foo
EOF
libc_cv_aarch64_variant_pcs=no
if AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS -nostdlib -nostartfiles $no_ssp -shared -fPIC -o conftest.so conftest.S]) \
&& AC_TRY_COMMAND([$READELF -dW conftest.so | grep -q AARCH64_VARIANT_PCS])
then
libc_cv_aarch64_variant_pcs=yes
fi
rm -rf conftest.*])
LIBC_CONFIG_VAR([aarch64-variant-pcs], [$libc_cv_aarch64_variant_pcs])
# Check if asm support armv8.2-a+sve
AC_CACHE_CHECK([for SVE support in assembler], [libc_cv_aarch64_sve_asm], [dnl
cat > conftest.s <<\EOF
ptrue p0.b
EOF
if AC_TRY_COMMAND(${CC-cc} -c -march=armv8.2-a+sve conftest.s 1>&AS_MESSAGE_LOG_FD); then
libc_cv_aarch64_sve_asm=yes
else
libc_cv_aarch64_sve_asm=no
fi
rm -f conftest*])
if test $libc_cv_aarch64_sve_asm = yes; then
AC_DEFINE(HAVE_AARCH64_SVE_ASM)
fi
if test x"$build_mathvec" = xnotset; then
build_mathvec=yes
fi
# Check if compiler is sufficient to build mathvec (needs SVE ACLE)
AC_CACHE_CHECK(for availability of SVE ACLE, libc_cv_has_sve_acle, [dnl
if test $build_mathvec = yes; then
cat > conftest.c <<EOF
#include <arm_sve.h>
EOF
if ! ${CC-cc} conftest.c -fsyntax-only; then
as_fn_error 1 "mathvec is enabled but compiler does not have SVE ACLE. Either use a compatible compiler or configure with --disable-mathvec (this results in incomplete ABI)."
fi
rm conftest.c
fi])