aboutsummaryrefslogtreecommitdiff
path: root/m4
diff options
context:
space:
mode:
Diffstat (limited to 'm4')
-rw-r--r--m4/tuklib_integer.m446
1 files changed, 45 insertions, 1 deletions
diff --git a/m4/tuklib_integer.m4 b/m4/tuklib_integer.m4
index c3c59fe3..dcc83d92 100644
--- a/m4/tuklib_integer.m4
+++ b/m4/tuklib_integer.m4
@@ -45,11 +45,26 @@ main(void)
])dnl
fi
+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])
+ ])
+
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 and 32-bit integers. By default, this is enabled
- only on x86, x86_64, and big endian PowerPC.]),
+ only on x86, x86_64, big endian PowerPC,
+ and some ARM systems.]),
[], [enable_unaligned_access=auto])
if test "x$enable_unaligned_access" = xauto ; then
# TODO: There may be other architectures, on which unaligned access
@@ -82,4 +97,33 @@ if test "x$enable_unaligned_access" = xyes ; then
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