1# asm-underscore.m4 serial 4
2dnl Copyright (C) 2010-2020 Free Software Foundation, Inc.
3dnl This file is free software; the Free Software Foundation
4dnl gives unlimited permission to copy and/or distribute it,
5dnl with or without modifications, as long as this notice is preserved.
6
7dnl From Bruno Haible. Based on as-underscore.m4 in GNU clisp.
8
9# gl_ASM_SYMBOL_PREFIX
10# Tests for the prefix of C symbols at the assembly language level and the
11# linker level. This prefix is either an underscore or empty. Defines the
12# C macro USER_LABEL_PREFIX to this prefix, and sets ASM_SYMBOL_PREFIX to
13# a stringified variant of this prefix.
14
15AC_DEFUN([gl_ASM_SYMBOL_PREFIX],
16[
17  AC_REQUIRE([AC_PROG_EGREP])
18  dnl We don't use GCC's __USER_LABEL_PREFIX__ here, because
19  dnl 1. It works only for GCC.
20  dnl 2. It is incorrectly defined on some platforms, in some GCC versions.
21  AC_REQUIRE([gl_C_ASM])
22  AC_CACHE_CHECK(
23    [whether C symbols are prefixed with underscore at the linker level],
24    [gl_cv_prog_as_underscore],
25    [cat > conftest.c <<EOF
26#ifdef __cplusplus
27extern "C" int foo (void);
28#endif
29int foo(void) { return 0; }
30EOF
31     # Look for the assembly language name in the .s file.
32     AC_TRY_COMMAND(${CC-cc} $CFLAGS $CPPFLAGS $gl_c_asm_opt conftest.c) >/dev/null 2>&1
33     if LC_ALL=C $EGREP '(^|[[^a-zA-Z0-9_]])_foo([[^a-zA-Z0-9_]]|$)' conftest.$gl_asmext >/dev/null; then
34       gl_cv_prog_as_underscore=yes
35     else
36       gl_cv_prog_as_underscore=no
37     fi
38     rm -f conftest*
39    ])
40  if test $gl_cv_prog_as_underscore = yes; then
41    USER_LABEL_PREFIX=_
42  else
43    USER_LABEL_PREFIX=
44  fi
45  AC_DEFINE_UNQUOTED([USER_LABEL_PREFIX], [$USER_LABEL_PREFIX],
46    [Define to the prefix of C symbols at the assembler and linker level,
47     either an underscore or empty.])
48  ASM_SYMBOL_PREFIX='"'${USER_LABEL_PREFIX}'"'
49  AC_SUBST([ASM_SYMBOL_PREFIX])
50])
51
52# gl_C_ASM
53# Determines how to produce an assembly language file from C source code.
54# Sets the variables:
55#   gl_asmext - the extension of assembly language output,
56#   gl_c_asm_opt - the C compiler option that produces assembly language output.
57
58AC_DEFUN([gl_C_ASM],
59[
60  AC_EGREP_CPP([MicrosoftCompiler],
61    [
62#ifdef _MSC_VER
63MicrosoftCompiler
64#endif
65    ],
66    [gl_asmext='asm'
67     gl_c_asm_opt='-c -Fa'
68    ],
69    [gl_asmext='s'
70     gl_c_asm_opt='-S'
71    ])
72])
73