149 lines
4.4 KiB
Plaintext
149 lines
4.4 KiB
Plaintext
#
|
|
# SYNOPSIS
|
|
#
|
|
# TUKLIB_INTEGER
|
|
#
|
|
# DESCRIPTION
|
|
#
|
|
# Checks for tuklib_integer.h:
|
|
# - Endianness
|
|
# - Does the compiler or the operating system provide byte swapping macros
|
|
# - Does the hardware support fast unaligned access to 16-bit, 32-bit,
|
|
# and 64-bit integers
|
|
#
|
|
# COPYING
|
|
#
|
|
# Author: Lasse Collin
|
|
#
|
|
|
|
AC_DEFUN_ONCE([TUKLIB_INTEGER], [
|
|
AC_REQUIRE([TUKLIB_COMMON])
|
|
AC_REQUIRE([AC_C_BIGENDIAN])
|
|
|
|
AC_MSG_CHECKING([if __builtin_bswap16/32/64 are supported])
|
|
AC_LINK_IFELSE([AC_LANG_PROGRAM([[]],
|
|
[[__builtin_bswap16(1);
|
|
__builtin_bswap32(1);
|
|
__builtin_bswap64(1);]])],
|
|
[
|
|
AC_DEFINE([HAVE___BUILTIN_BSWAPXX], [1],
|
|
[Define to 1 if the GNU C extensions
|
|
__builtin_bswap16/32/64 are supported.])
|
|
AC_MSG_RESULT([yes])
|
|
], [
|
|
AC_MSG_RESULT([no])
|
|
|
|
# Look for other byteswapping methods.
|
|
AC_CHECK_HEADERS([byteswap.h sys/endian.h sys/byteorder.h], [break])
|
|
|
|
# Even if we have byteswap.h we may lack the specific macros/functions.
|
|
if test x$ac_cv_header_byteswap_h = xyes ; then
|
|
m4_foreach([FUNC], [bswap_16,bswap_32,bswap_64], [
|
|
AC_MSG_CHECKING([if FUNC is available])
|
|
AC_LINK_IFELSE([AC_LANG_SOURCE([
|
|
#include <byteswap.h>
|
|
int
|
|
main(void)
|
|
{
|
|
FUNC[](42);
|
|
return 0;
|
|
}
|
|
])], [
|
|
AC_DEFINE(HAVE_[]m4_toupper(FUNC), [1],
|
|
[Define to 1 if] FUNC [is available.])
|
|
AC_MSG_RESULT([yes])
|
|
], [AC_MSG_RESULT([no])])
|
|
|
|
])dnl
|
|
fi
|
|
])
|
|
|
|
AC_MSG_CHECKING([if unaligned memory access should be used])
|
|
AC_ARG_ENABLE([unaligned-access], AS_HELP_STRING([--enable-unaligned-access],
|
|
[Enable if the system supports *fast* unaligned memory access
|
|
with 16-bit, 32-bit, and 64-bit integers. By default,
|
|
this is enabled on x86, x86-64,
|
|
32/64-bit big endian PowerPC,
|
|
64-bit little endian PowerPC,
|
|
and some ARM, ARM64, and RISC-V systems.]),
|
|
[], [enable_unaligned_access=auto])
|
|
if test "x$enable_unaligned_access" = xauto ; then
|
|
# NOTE: There might be other architectures on which unaligned access
|
|
# is fast.
|
|
case $host_cpu in
|
|
i?86|x86_64|powerpc|powerpc64|powerpc64le)
|
|
enable_unaligned_access=yes
|
|
;;
|
|
arm*|aarch64*|riscv*)
|
|
# On 32-bit and 64-bit ARM, GCC and Clang
|
|
# #define __ARM_FEATURE_UNALIGNED if
|
|
# unaligned access is supported.
|
|
#
|
|
# Exception: GCC at least up to 13.2.0
|
|
# defines it even when using -mstrict-align
|
|
# so in that case this autodetection goes wrong.
|
|
# Most of the time -mstrict-align isn't used so it
|
|
# shouldn't be a common problem in practice. See:
|
|
# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111555
|
|
#
|
|
# RISC-V C API Specification says that if
|
|
# __riscv_misaligned_fast is defined then
|
|
# unaligned access is known to be fast.
|
|
#
|
|
# MSVC is handled as a special case: We assume that
|
|
# 32/64-bit ARM supports fast unaligned access.
|
|
# If MSVC gets RISC-V support then this will assume
|
|
# fast unaligned access on RISC-V too.
|
|
AC_COMPILE_IFELSE([AC_LANG_SOURCE([
|
|
#if !defined(__ARM_FEATURE_UNALIGNED) \
|
|
&& !defined(__riscv_misaligned_fast) \
|
|
&& !defined(_MSC_VER)
|
|
compile error
|
|
#endif
|
|
int main(void) { return 0; }
|
|
])], [enable_unaligned_access=yes], [enable_unaligned_access=no])
|
|
;;
|
|
*)
|
|
enable_unaligned_access=no
|
|
;;
|
|
esac
|
|
fi
|
|
if test "x$enable_unaligned_access" = xyes ; then
|
|
AC_DEFINE([TUKLIB_FAST_UNALIGNED_ACCESS], [1], [Define to 1 if
|
|
the system supports fast unaligned access to 16-bit,
|
|
32-bit, and 64-bit integers.])
|
|
AC_MSG_RESULT([yes])
|
|
else
|
|
AC_MSG_RESULT([no])
|
|
fi
|
|
|
|
AC_MSG_CHECKING([if unsafe type punning should be used])
|
|
AC_ARG_ENABLE([unsafe-type-punning],
|
|
AS_HELP_STRING([--enable-unsafe-type-punning],
|
|
[This introduces strict aliasing violations and may result
|
|
in broken code. However, this might improve performance in
|
|
some cases, especially with old compilers (e.g.
|
|
GCC 3 and early 4.x on x86, GCC < 6 on ARMv6 and ARMv7).]),
|
|
[], [enable_unsafe_type_punning=no])
|
|
if test "x$enable_unsafe_type_punning" = xyes ; then
|
|
AC_DEFINE([TUKLIB_USE_UNSAFE_TYPE_PUNNING], [1], [Define to 1 to use
|
|
unsafe type punning, e.g. char *x = ...; *(int *)x = 123;
|
|
which violates strict aliasing rules and thus is
|
|
undefined behavior and might result in broken code.])
|
|
AC_MSG_RESULT([yes])
|
|
else
|
|
AC_MSG_RESULT([no])
|
|
fi
|
|
|
|
AC_MSG_CHECKING([if __builtin_assume_aligned is supported])
|
|
AC_LINK_IFELSE([AC_LANG_PROGRAM([[]], [[__builtin_assume_aligned("", 1);]])],
|
|
[
|
|
AC_DEFINE([HAVE___BUILTIN_ASSUME_ALIGNED], [1],
|
|
[Define to 1 if the GNU C extension
|
|
__builtin_assume_aligned is supported.])
|
|
AC_MSG_RESULT([yes])
|
|
], [
|
|
AC_MSG_RESULT([no])
|
|
])
|
|
])dnl
|