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# asm-underscore.m4 serial 5
dnl Copyright (C) 2010-2024 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 <<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 $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='"'${USER_LABEL_PREFIX}'"'
AC_SUBST([ASM_SYMBOL_PREFIX])
])
# gl_C_ASM
# Determines how to produce an assembly language file from C source code.
# Sets the variables:
# gl_asmext - the extension of assembly language output,
# gl_c_asm_opt - the C compiler option that produces assembly language output.
AC_DEFUN([gl_C_ASM],
[
AC_EGREP_CPP([MicrosoftCompiler],
[
#ifdef _MSC_VER
MicrosoftCompiler
#endif
],
[dnl Microsoft's 'cl' and 'clang-cl' produce an .asm file, whereas 'clang'
dnl produces a .s file. Need to distinguish 'clang' and 'clang-cl'.
rm -f conftest*
echo 'int dummy;' > conftest.c
AC_TRY_COMMAND(${CC-cc} $CFLAGS $CPPFLAGS -c conftest.c) >/dev/null 2>&1
if test -f conftest.o; then
gl_asmext='s'
gl_c_asm_opt='-S'
else
gl_asmext='asm'
gl_c_asm_opt='-c -Fa'
fi
rm -f conftest*
],
[gl_asmext='s'
gl_c_asm_opt='-S'
])
])
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