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# 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])
])
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