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1# asm-underscore.m4 serial 2
2dnl Copyright (C) 2010-2012 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  dnl We don't use GCC's __USER_LABEL_PREFIX__ here, because
18  dnl 1. It works only for GCC.
19  dnl 2. It is incorrectly defined on some platforms, in some GCC versions.
20  AC_REQUIRE([gl_C_ASM])
21  AC_CACHE_CHECK(
22    [whether C symbols are prefixed with underscore at the linker level],
23    [gl_cv_prog_as_underscore],
24    [cat > conftest.c <<EOF
25#ifdef __cplusplus
26extern "C" int foo (void);
27#endif
28int foo(void) { return 0; }
29EOF
30     # Look for the assembly language name in the .s file.
31     AC_TRY_COMMAND(${CC-cc} $CFLAGS $CPPFLAGS $gl_c_asm_opt conftest.c) >/dev/null 2>&1
32     if grep _foo conftest.$gl_asmext >/dev/null ; then
33       gl_cv_prog_as_underscore=yes
34     else
35       gl_cv_prog_as_underscore=no
36     fi
37     rm -f conftest*
38    ])
39  if test $gl_cv_prog_as_underscore = yes; then
40    USER_LABEL_PREFIX=_
41  else
42    USER_LABEL_PREFIX=
43  fi
44  AC_DEFINE_UNQUOTED([USER_LABEL_PREFIX], [$USER_LABEL_PREFIX],
45    [Define to the prefix of C symbols at the assembler and linker level,
46     either an underscore or empty.])
47  ASM_SYMBOL_PREFIX='"'${USER_LABEL_PREFIX}'"'
48  AC_SUBST([ASM_SYMBOL_PREFIX])
49])
50
51# gl_C_ASM
52# Determines how to produce an assembly language file from C source code.
53# Sets the variables:
54#   gl_asmext - the extension of assembly language output,
55#   gl_c_asm_opt - the C compiler option that produces assembly language output.
56
57AC_DEFUN([gl_C_ASM],
58[
59  AC_EGREP_CPP([MicrosoftCompiler],
60    [
61#ifdef _MSC_VER
62MicrosoftCompiler
63#endif
64    ],
65    [gl_asmext='asm'
66     gl_c_asm_opt='-c -Fa'
67    ],
68    [gl_asmext='s'
69     gl_c_asm_opt='-S'
70    ])
71])
72