elfos.h

gcc-2.95.3 Linux下最常用的C编译器

/* elfos.h  --  operating system specific defines to be used when
   targeting GCC for some generic ELF system
   Copyright (C) 1991, 1994, 1995, 1999, 2000 Free Software Foundation, Inc.
   Based on svr4.h contributed by Ron Guilmette ([e-mail]).

This file is part of GNU CC.

GNU CC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU CC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU CC; see the file COPYING.  If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

/* For the sake of libgcc2.c, indicate target supports atexit.  */
#define HAVE_ATEXIT

#undef  ENDFILE_SPEC
#define ENDFILE_SPEC "crtend.o%s"

#undef	STARTFILE_SPEC
#define STARTFILE_SPEC "%{!shared: \
			 %{!symbolic: \
			  %{pg:gcrt0.o%s}%{!pg:%{p:mcrt0.o%s}%{!p:crt0.o%s}}}}\
			crtbegin.o%s"

/* Attach a special .ident directive to the end of the file to identify
   the version of GCC which compiled this code.  The format of the
   .ident string is patterned after the ones produced by native svr4
   C compilers.  */

#define IDENT_ASM_OP ".ident"

#define ASM_FILE_END(FILE)					\
do {				 				\
     if (!flag_no_ident)					\
	fprintf ((FILE), "\t%s\t\"GCC: (GNU) %s\"\n",		\
		 IDENT_ASM_OP, version_string);			\
   } while (0)

/* Output #ident as a .ident.  */

#define ASM_OUTPUT_IDENT(FILE, NAME) \
  fprintf (FILE, "\t%s\t\"%s\"\n", IDENT_ASM_OP, NAME);

/* Use periods rather than dollar signs in special g++ assembler names.  */

#define NO_DOLLAR_IN_LABEL

/* Writing `int' for a bitfield forces int alignment for the structure.  */

#define PCC_BITFIELD_TYPE_MATTERS 1

/* Implicit library calls should use memcpy, not bcopy, etc.  */

#define TARGET_MEM_FUNCTIONS

/* Handle #pragma weak and #pragma pack.  */

#define HANDLE_SYSV_PRAGMA

/* System V Release 4 uses DWARF debugging info.  */

#define DWARF_DEBUGGING_INFO

/* All ELF targets can support DWARF-2.  */

#define DWARF2_DEBUGGING_INFO

/* Also allow them to support STABS debugging.  */

#include "dbxelf.h"

/* The GNU tools operate better with stabs.  Since we don't have
   any native tools to be compatible with, default to stabs.  */

#ifndef PREFERRED_DEBUGGING_TYPE
#define PREFERRED_DEBUGGING_TYPE DBX_DEBUG
#endif

#undef ASM_BYTE_OP
#define ASM_BYTE_OP	".byte"

#undef SET_ASM_OP
#define SET_ASM_OP	".set"

/* This is how to begin an assembly language file.  Most svr4 assemblers want
   at least a .file directive to come first, and some want to see a .version
   directive come right after that.  Here we just establish a default
   which generates only the .file directive.  If you need a .version
   directive for any specific target, you should override this definition
   in the target-specific file which includes this one.  */

#undef ASM_FILE_START
#define ASM_FILE_START(FILE)                                    \
  output_file_directive ((FILE), main_input_filename)

/* This is how to allocate empty space in some section.  The .zero
   pseudo-op is used for this on most svr4 assemblers.  */

#define SKIP_ASM_OP	".zero"

#undef ASM_OUTPUT_SKIP
#define ASM_OUTPUT_SKIP(FILE,SIZE) \
  fprintf (FILE, "\t%s\t%u\n", SKIP_ASM_OP, (SIZE))

/* This is how to output a reference to a user-level label named NAME.
   `assemble_name' uses this.

   For System V Release 4 the convention is *not* to prepend a leading
   underscore onto user-level symbol names.  */

#undef ASM_OUTPUT_LABELREF
#define ASM_OUTPUT_LABELREF(FILE,NAME) fprintf (FILE, "%s", NAME)

/* This is how to output an internal numbered label where
   PREFIX is the class of label and NUM is the number within the class.

   For most svr4 systems, the convention is that any symbol which begins
   with a period is not put into the linker symbol table by the assembler.  */

#undef ASM_OUTPUT_INTERNAL_LABEL
#define ASM_OUTPUT_INTERNAL_LABEL(FILE, PREFIX, NUM)			\
do {									\
  fprintf (FILE, ".%s%d:\n", PREFIX, NUM);				\
} while (0)

/* This is how to store into the string LABEL
   the symbol_ref name of an internal numbered label where
   PREFIX is the class of label and NUM is the number within the class.
   This is suitable for output with `assemble_name'.

   For most svr4 systems, the convention is that any symbol which begins
   with a period is not put into the linker symbol table by the assembler.  */

#undef ASM_GENERATE_INTERNAL_LABEL
#define ASM_GENERATE_INTERNAL_LABEL(LABEL, PREFIX, NUM)			\
do {									\
  sprintf (LABEL, "*.%s%d", PREFIX, NUM);				\
} while (0)

/* Output the label which precedes a jumptable.  Note that for all svr4
   systems where we actually generate jumptables (which is to say every
   svr4 target except i386, where we use casesi instead) we put the jump-
   tables into the .rodata section and since other stuff could have been
   put into the .rodata section prior to any given jumptable, we have to
   make sure that the location counter for the .rodata section gets pro-
   perly re-aligned prior to the actual beginning of the jump table.  */

#define ALIGN_ASM_OP ".align"

#ifndef ASM_OUTPUT_BEFORE_CASE_LABEL
#define ASM_OUTPUT_BEFORE_CASE_LABEL(FILE,PREFIX,NUM,TABLE) \
  ASM_OUTPUT_ALIGN ((FILE), 2);
#endif

#undef ASM_OUTPUT_CASE_LABEL
#define ASM_OUTPUT_CASE_LABEL(FILE,PREFIX,NUM,JUMPTABLE)		\
  do {									\
    ASM_OUTPUT_BEFORE_CASE_LABEL (FILE, PREFIX, NUM, JUMPTABLE)		\
    ASM_OUTPUT_INTERNAL_LABEL (FILE, PREFIX, NUM);			\
  } while (0)

/* The standard SVR4 assembler seems to require that certain builtin
   library routines (e.g. .udiv) be explicitly declared as .globl
   in each assembly file where they are referenced.  */

#define ASM_OUTPUT_EXTERNAL_LIBCALL(FILE, FUN)				\
  ASM_GLOBALIZE_LABEL (FILE, XSTR (FUN, 0))

/* This says how to output assembler code to declare an
   uninitialized external linkage data object.  Under SVR4,
   the linker seems to want the alignment of data objects
   to depend on their types.  We do exactly that here.  */

#define COMMON_ASM_OP	".comm"

#undef ASM_OUTPUT_ALIGNED_COMMON
#define ASM_OUTPUT_ALIGNED_COMMON(FILE, NAME, SIZE, ALIGN)		\
do {									\
  fprintf ((FILE), "\t%s\t", COMMON_ASM_OP);				\
  assemble_name ((FILE), (NAME));					\
  fprintf ((FILE), ",%u,%u\n", (SIZE), (ALIGN) / BITS_PER_UNIT);	\
} while (0)

/* This says how to output assembler code to declare an
   uninitialized internal linkage data object.  Under SVR4,
   the linker seems to want the alignment of data objects
   to depend on their types.  We do exactly that here.  */

#define LOCAL_ASM_OP	".local"

#undef ASM_OUTPUT_ALIGNED_LOCAL
#define ASM_OUTPUT_ALIGNED_LOCAL(FILE, NAME, SIZE, ALIGN)		\
do {									\
  fprintf ((FILE), "\t%s\t", LOCAL_ASM_OP);				\
  assemble_name ((FILE), (NAME));					\
  fprintf ((FILE), "\n");						\
  ASM_OUTPUT_ALIGNED_COMMON (FILE, NAME, SIZE, ALIGN);			\
} while (0)

/* This is the pseudo-op used to generate a 32-bit word of data with a
   specific value in some section.  This is the same for all known svr4
   assemblers.  */

#define INT_ASM_OP		".long"

/* This is the pseudo-op used to generate a contiguous sequence of byte
   values from a double-quoted string WITHOUT HAVING A TERMINATING NUL
   AUTOMATICALLY APPENDED.  This is the same for most svr4 assemblers.  */

#undef ASCII_DATA_ASM_OP
#define ASCII_DATA_ASM_OP	".ascii"

/* Support const sections and the ctors and dtors sections for g++.
   Note that there appears to be two different ways to support const
   sections at the moment.  You can either #define the symbol
   READONLY_DATA_SECTION (giving it some code which switches to the
   readonly data section) or else you can #define the symbols
   EXTRA_SECTIONS, EXTRA_SECTION_FUNCTIONS, SELECT_SECTION, and
   SELECT_RTX_SECTION.  We do both here just to be on the safe side.  */

#define USE_CONST_SECTION	1

#define CONST_SECTION_ASM_OP	".section\t.rodata"

/* Define the pseudo-ops used to switch to the .ctors and .dtors sections.

   Note that we want to give these sections the SHF_WRITE attribute
   because these sections will actually contain data (i.e. tables of
   addresses of functions in the current root executable or shared library
   file) and, in the case of a shared library, the relocatable addresses
   will have to be properly resolved/relocated (and then written into) by
   the dynamic linker when it actually attaches the given shared library
   to the executing process.  (Note that on SVR4, you may wish to use the
   `-z text' option to the ELF linker, when building a shared library, as
   an additional check that you are doing everything right.  But if you do
   use the `-z text' option when building a shared library, you will get
   errors unless the .ctors and .dtors sections are marked as writable
   via the SHF_WRITE attribute.)  */

#define CTORS_SECTION_ASM_OP	".section\t.ctors,\"aw\""
#define DTORS_SECTION_ASM_OP	".section\t.dtors,\"aw\""

/* On svr4, we *do* have support for the .init and .fini sections, and we
   can put stuff in there to be executed before and after `main'.  We let
   crtstuff.c and other files know this by defining the following symbols.
   The definitions say how to change sections to the .init and .fini
   sections.  This is the same for all known svr4 assemblers.  */

#define INIT_SECTION_ASM_OP	".section\t.init"
#define FINI_SECTION_ASM_OP	".section\t.fini"

/* A default list of other sections which we might be "in" at any given
   time.  For targets that use additional sections (e.g. .tdesc) you
   should override this definition in the target-specific file which
   includes this file.  */

#undef EXTRA_SECTIONS
#define EXTRA_SECTIONS in_const, in_ctors, in_dtors

/* A default list of extra section function definitions.  For targets
   that use additional sections (e.g. .tdesc) you should override this
   definition in the target-specific file which includes this file.  */

#undef EXTRA_SECTION_FUNCTIONS
#define EXTRA_SECTION_FUNCTIONS						\
  CONST_SECTION_FUNCTION						\
  CTORS_SECTION_FUNCTION						\
  DTORS_SECTION_FUNCTION

#define READONLY_DATA_SECTION() const_section ()

extern void text_section ();

#define CONST_SECTION_FUNCTION						\
void									\
const_section ()							\
{									\
  if (!USE_CONST_SECTION)						\
    text_section();							\
  else if (in_section != in_const)					\
    {									\
      fprintf (asm_out_file, "%s\n", CONST_SECTION_ASM_OP);		\
      in_section = in_const;						\
    }									\
}

#define CTORS_SECTION_FUNCTION						\
void									\
ctors_section ()							\
{									\
  if (in_section != in_ctors)						\
    {									\
      fprintf (asm_out_file, "%s\n", CTORS_SECTION_ASM_OP);		\
      in_section = in_ctors;						\
    }									\
}

#define DTORS_SECTION_FUNCTION						\
void									\
dtors_section ()							\
{									\
  if (in_section != in_dtors)						\
    {									\
      fprintf (asm_out_file, "%s\n", DTORS_SECTION_ASM_OP);		\
      in_section = in_dtors;						\
    }									\
}

/* Switch into a generic section.
   This is currently only used to support section attributes.  */

#define ASM_OUTPUT_SECTION_NAME(FILE, DECL, NAME, RELOC)		\
do {									\
  static struct section_info						\
    {									\
      struct section_info *next;				        \
      char *name;						        \
      enum sect_enum {SECT_RW, SECT_RO, SECT_EXEC} type;		\
    } *sections;							\
  struct section_info *s;						\
  char *mode;								\
  enum sect_enum type;							\
									\
  for (s = sections; s; s = s->next)					\
    if (!strcmp (NAME, s->name))					\
      break;								\
									\
  if (DECL && TREE_CODE (DECL) == FUNCTION_DECL)			\
    type = SECT_EXEC, mode = "ax";					\
  else if (DECL && DECL_READONLY_SECTION (DECL, RELOC))			\
    type = SECT_RO, mode = "a";						\
  else									\
    type = SECT_RW, mode = "aw";					\
									\
  if (s == 0)								\
    {									\
      s = (struct section_info *) xmalloc (sizeof (struct section_info));  \
      s->name = xmalloc ((strlen (NAME) + 1) * sizeof (*NAME));		\
      strcpy (s->name, NAME);						\
      s->type = type;							\
      s->next = sections;						\
      sections = s;							\
      fprintf (FILE, ".section\t%s,\"%s\",@progbits\n", NAME, mode);	\