# asm-underscore.m4 serial 1

dnl Copyright (C) 2010 Free Software Foundation, Inc.

dnl This file is free software; the Free Software Foundation

dnl gives unlimited permission to copy and/or distribute it,

dnl with or without modifications, as long as this notice is preserved.

dnl From Bruno Haible. Based on as-underscore.m4 in GNU clisp.

# gl_ASM_SYMBOL_PREFIX

# Tests for the prefix of C symbols at the assembly language level and the

# linker level. This prefix is either an underscore or empty. Defines the

# C macro USER_LABEL_PREFIX to this prefix, and sets ASM_SYMBOL_PREFIX to

# a stringified variant of this prefix.

AC_DEFUN([gl_ASM_SYMBOL_PREFIX],

[

dnl We don't use GCC's __USER_LABEL_PREFIX__ here, because

dnl 1. It works only for GCC.

dnl 2. It is incorrectly defined on some platforms, in some GCC versions.

AC_CACHE_CHECK(

[whether C symbols are prefixed with underscore at the linker level],

[gl_cv_prog_as_underscore],

[cat > conftest.c <<EOF

#ifdef __cplusplus

extern "C" int foo (void);

#endif

int foo(void) { return 0; }

EOF

# Look for the assembly language name in the .s file.

AC_TRY_COMMAND(${CC-cc} $CFLAGS $CPPFLAGS -S conftest.c) >/dev/null 2>&1

if grep _foo conftest.s >/dev/null ; then

gl_cv_prog_as_underscore=yes

else

gl_cv_prog_as_underscore=no

fi

rm -f conftest*

])

if test $gl_cv_prog_as_underscore = yes; then

USER_LABEL_PREFIX=_

else

USER_LABEL_PREFIX=

fi

AC_DEFINE_UNQUOTED([USER_LABEL_PREFIX], [$USER_LABEL_PREFIX],

[Define to the prefix of C symbols at the assembler and linker level,

either an underscore or empty.])

ASM_SYMBOL_PREFIX='"'${USER_LABEL_PREFIX}'"'

AC_SUBST([ASM_SYMBOL_PREFIX])

])