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Diffstat (limited to 'm4/ax_gcc_var_attribute.m4')
| -rw-r--r-- | m4/ax_gcc_var_attribute.m4 | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/m4/ax_gcc_var_attribute.m4 b/m4/ax_gcc_var_attribute.m4 new file mode 100644 index 0000000000..247cc4ab3e --- /dev/null +++ b/m4/ax_gcc_var_attribute.m4 @@ -0,0 +1,141 @@ +# =========================================================================== +# http://www.gnu.org/software/autoconf-archive/ax_gcc_var_attribute.html +# =========================================================================== +# +# SYNOPSIS +# +# AX_GCC_VAR_ATTRIBUTE(ATTRIBUTE) +# +# DESCRIPTION +# +# This macro checks if the compiler supports one of GCC's variable +# attributes; many other compilers also provide variable attributes with +# the same syntax. Compiler warnings are used to detect supported +# attributes as unsupported ones are ignored by default so quieting +# warnings when using this macro will yield false positives. +# +# The ATTRIBUTE parameter holds the name of the attribute to be checked. +# +# If ATTRIBUTE is supported define HAVE_VAR_ATTRIBUTE_<ATTRIBUTE>. +# +# The macro caches its result in the ax_cv_have_var_attribute_<attribute> +# variable. +# +# The macro currently supports the following variable attributes: +# +# aligned +# cleanup +# common +# nocommon +# deprecated +# mode +# packed +# tls_model +# unused +# used +# vector_size +# weak +# dllimport +# dllexport +# init_priority +# +# Unsuppored variable attributes will be tested against a global integer +# variable and without any arguments given to the attribute itself; the +# result of this check might be wrong or meaningless so use with care. +# +# LICENSE +# +# Copyright (c) 2013 Gabriele Svelto <gabriele.svelto@gmail.com> +# +# Copying and distribution of this file, with or without modification, are +# permitted in any medium without royalty provided the copyright notice +# and this notice are preserved. This file is offered as-is, without any +# warranty. + +#serial 3 + +AC_DEFUN([AX_GCC_VAR_ATTRIBUTE], [ + AS_VAR_PUSHDEF([ac_var], [ax_cv_have_var_attribute_$1]) + + AC_CACHE_CHECK([for __attribute__(($1))], [ac_var], [ + AC_LINK_IFELSE([AC_LANG_PROGRAM([ + m4_case([$1], + [aligned], [ + int foo __attribute__(($1(32))); + ], + [cleanup], [ + int bar(int *t) { return *t; }; + ], + [common], [ + int foo __attribute__(($1)); + ], + [nocommon], [ + int foo __attribute__(($1)); + ], + [deprecated], [ + int foo __attribute__(($1)) = 0; + ], + [mode], [ + long foo __attribute__(($1(word))); + ], + [packed], [ + struct bar { + int baz __attribute__(($1)); + }; + ], + [tls_model], [ + __thread int bar1 __attribute__(($1("global-dynamic"))); + __thread int bar2 __attribute__(($1("local-dynamic"))); + __thread int bar3 __attribute__(($1("initial-exec"))); + __thread int bar4 __attribute__(($1("local-exec"))); + ], + [unused], [ + int foo __attribute__(($1)); + ], + [used], [ + int foo __attribute__(($1)); + ], + [vector_size], [ + int foo __attribute__(($1(16))); + ], + [weak], [ + int foo __attribute__(($1)); + ], + [dllimport], [ + int foo __attribute__(($1)); + ], + [dllexport], [ + int foo __attribute__(($1)); + ], + [init_priority], [ + struct bar { bar() {} ~bar() {} }; + bar b __attribute__(($1(65535/2))); + ], + [ + m4_warn([syntax], [Unsupported attribute $1, the test may fail]) + int foo __attribute__(($1)); + ] + )], [ + m4_case([$1], + [cleanup], [ + int foo __attribute__(($1(bar))) = 0; + foo = foo + 1; + ], + [] + )]) + ], + dnl GCC doesn't exit with an error if an unknown attribute is + dnl provided but only outputs a warning, so accept the attribute + dnl only if no warning were issued. + [AS_IF([test -s conftest.err], + [AS_VAR_SET([ac_var], [no])], + [AS_VAR_SET([ac_var], [yes])])], + [AS_VAR_SET([ac_var], [no])]) + ]) + + AS_IF([test yes = AS_VAR_GET([ac_var])], + [AC_DEFINE_UNQUOTED(AS_TR_CPP(HAVE_VAR_ATTRIBUTE_$1), 1, + [Define to 1 if the system has the `$1' variable attribute])], []) + + AS_VAR_POPDEF([ac_var]) +]) |