# asm-underscore.m4 serial 4

dnl Copyright (C) 2010-2018 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],

[

  AC_REQUIRE([AC_PROG_EGREP])

  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_REQUIRE([gl_C_ASM])

  AC_CACHE_CHECK(

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

    [gl_cv_prog_as_underscore],

    [cat > conftest.c <

#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 $gl_c_asm_opt conftest.c) >/dev/null 2>&1

     if LC_ALL=C $EGREP '(^|[[^a-zA-Z0-9_]])_foo([[^a-zA-Z0-9_]]|$)' conftest.$gl_asmext >/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])

])

# gl_C_ASM

# Determines how to produce an assembly language file from C source code.

# Sets the variables:

#   gl_asmext - the extension of assembly language output,

#   gl_c_asm_opt - the C compiler option that produces assembly language output.

AC_DEFUN([gl_C_ASM],

[

  AC_EGREP_CPP([MicrosoftCompiler],

    [

#ifdef _MSC_VER

MicrosoftCompiler

#endif

    ],

    [gl_asmext='asm'

     gl_c_asm_opt='-c -Fa'

    ],

    [gl_asmext='s'

     gl_c_asm_opt='-S'

    ])

])