| 1 | # asm-underscore.m4 serial 5
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| 2 | dnl Copyright (C) 2010-2021 Free Software Foundation, Inc.
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| 3 | dnl This file is free software; the Free Software Foundation
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| 4 | dnl gives unlimited permission to copy and/or distribute it,
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| 5 | dnl with or without modifications, as long as this notice is preserved.
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| 6 |
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| 7 | dnl From Bruno Haible. Based on as-underscore.m4 in GNU clisp.
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| 8 |
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| 9 | # gl_ASM_SYMBOL_PREFIX
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| 10 | # Tests for the prefix of C symbols at the assembly language level and the
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| 11 | # linker level. This prefix is either an underscore or empty. Defines the
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| 12 | # C macro USER_LABEL_PREFIX to this prefix, and sets ASM_SYMBOL_PREFIX to
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| 13 | # a stringified variant of this prefix.
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| 14 |
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| 15 | AC_DEFUN([gl_ASM_SYMBOL_PREFIX],
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| 16 | [
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| 17 | AC_REQUIRE([AC_PROG_EGREP])
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| 18 | dnl We don't use GCC's __USER_LABEL_PREFIX__ here, because
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| 19 | dnl 1. It works only for GCC.
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| 20 | dnl 2. It is incorrectly defined on some platforms, in some GCC versions.
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| 21 | AC_REQUIRE([gl_C_ASM])
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| 22 | AC_CACHE_CHECK(
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| 23 | [whether C symbols are prefixed with underscore at the linker level],
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| 24 | [gl_cv_prog_as_underscore],
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| 25 | [cat > conftest.c <<EOF
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| 26 | #ifdef __cplusplus
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| 27 | extern "C" int foo (void);
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| 28 | #endif
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| 29 | int foo(void) { return 0; }
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| 30 | EOF
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| 31 | # Look for the assembly language name in the .s file.
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| 32 | AC_TRY_COMMAND(${CC-cc} $CFLAGS $CPPFLAGS $gl_c_asm_opt conftest.c) >/dev/null 2>&1
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| 33 | if LC_ALL=C $EGREP '(^|[[^a-zA-Z0-9_]])_foo([[^a-zA-Z0-9_]]|$)' conftest.$gl_asmext >/dev/null; then
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| 34 | gl_cv_prog_as_underscore=yes
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| 35 | else
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| 36 | gl_cv_prog_as_underscore=no
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| 37 | fi
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| 38 | rm -f conftest*
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| 39 | ])
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| 40 | if test $gl_cv_prog_as_underscore = yes; then
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| 41 | USER_LABEL_PREFIX=_
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| 42 | else
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| 43 | USER_LABEL_PREFIX=
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| 44 | fi
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| 45 | AC_DEFINE_UNQUOTED([USER_LABEL_PREFIX], [$USER_LABEL_PREFIX],
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| 46 | [Define to the prefix of C symbols at the assembler and linker level,
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| 47 | either an underscore or empty.])
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| 48 | ASM_SYMBOL_PREFIX='"'${USER_LABEL_PREFIX}'"'
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| 49 | AC_SUBST([ASM_SYMBOL_PREFIX])
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| 50 | ])
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| 51 |
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| 52 | # gl_C_ASM
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| 53 | # Determines how to produce an assembly language file from C source code.
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| 54 | # Sets the variables:
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| 55 | # gl_asmext - the extension of assembly language output,
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| 56 | # gl_c_asm_opt - the C compiler option that produces assembly language output.
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| 57 |
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| 58 | AC_DEFUN([gl_C_ASM],
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| 59 | [
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| 60 | AC_EGREP_CPP([MicrosoftCompiler],
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| 61 | [
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| 62 | #ifdef _MSC_VER
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| 63 | MicrosoftCompiler
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| 64 | #endif
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| 65 | ],
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| 66 | [dnl Microsoft's 'cl' and 'clang-cl' produce an .asm file, whereas 'clang'
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| 67 | dnl produces a .s file. Need to distinguish 'clang' and 'clang-cl'.
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| 68 | rm -f conftest*
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| 69 | echo 'int dummy;' > conftest.c
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| 70 | AC_TRY_COMMAND(${CC-cc} $CFLAGS $CPPFLAGS -c conftest.c) >/dev/null 2>&1
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| 71 | if test -f conftest.o; then
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| 72 | gl_asmext='s'
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| 73 | gl_c_asm_opt='-S'
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| 74 | else
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| 75 | gl_asmext='asm'
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| 76 | gl_c_asm_opt='-c -Fa'
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| 77 | fi
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| 78 | rm -f conftest*
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| 79 | ],
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| 80 | [gl_asmext='s'
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| 81 | gl_c_asm_opt='-S'
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| 82 | ])
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| 83 | ])
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