diff options
Diffstat (limited to 'config/bitfields.m4')
| -rw-r--r-- | config/bitfields.m4 | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/config/bitfields.m4 b/config/bitfields.m4 new file mode 100644 index 00000000000..8185cd302a9 --- /dev/null +++ b/config/bitfields.m4 @@ -0,0 +1,25 @@ +dnl Copyright (C) 2015 Free Software Foundation, Inc. +dnl This file is free software, distributed under the terms of the GNU +dnl General Public License. As a special exception to the GNU General +dnl Public License, this file may be distributed as part of a program +dnl that contains a configuration script generated by Autoconf, under +dnl the same distribution terms as the rest of that program. + +# Define HAVE_BITFIELD_TYPE_MATTERS if the type of bitfields effects their +# alignment. + +AC_DEFUN([gt_BITFIELD_TYPE_MATTERS], +[ + AC_CACHE_CHECK([if the type of bitfields matters], gt_cv_bitfield_type_matters, + [ + AC_TRY_COMPILE( + [struct foo1 { char x; char y:1; char z; }; +struct foo2 { char x; long long int y:1; char z; }; +int foo1test[ sizeof (struct foo1) < sizeof (struct foo2) ? 1 : -1 ]; ], + [], gt_cv_bitfield_type_matters=yes, gt_cv_bitfield_type_matters=no) + ]) + if test $gt_cv_bitfield_type_matters = yes; then + AC_DEFINE(HAVE_BITFIELD_TYPE_MATTERS, 1, + [Define if the type of bitfields effects alignment.]) + fi +]) |