elf.h

gcc-2.95.3 Linux下最常用的C编译器

/* Definitions of target machine for GNU compiler.  MIPS R3000 version with
   GOFAST floating point library.
   Copyright (C) 1994, 1997, 1999 Free Software Foundation, Inc.

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.  */

/* Use ELF.  */
#define OBJECT_FORMAT_ELF

/* Until we figure out what MIPS ELF targets normally use, just do
   stabs in ELF.  */
#ifndef PREFERRED_DEBUGGING_TYPE
#define PREFERRED_DEBUGGING_TYPE DBX_DEBUG
#endif

/* Mostly like ECOFF.  */
#include "gofast.h"
#include "mips/ecoff.h"

/* We need to use .esize and .etype instead of .size and .type to
   avoid conflicting with ELF directives.  */
#undef PUT_SDB_SIZE
#define PUT_SDB_SIZE(a)					\
do {							\
  extern FILE *asm_out_text_file;			\
  fprintf (asm_out_text_file, "\t.esize\t%d;", (a));	\
} while (0)

#undef PUT_SDB_TYPE
#define PUT_SDB_TYPE(a)					\
do {							\
  extern FILE *asm_out_text_file;			\
  fprintf (asm_out_text_file, "\t.etype\t0x%x;", (a));	\
} while (0)

/* Biggest alignment supported by the object file format of this
   machine.  Use this macro to limit the alignment which can be
   specified using the `__attribute__ ((aligned (N)))' construct.  If
   not defined, the default value is `BIGGEST_ALIGNMENT'.  */

#define MAX_OFILE_ALIGNMENT (32768*8)

/* A C statement to output something to the assembler file to switch to section
   NAME for object DECL which is either a FUNCTION_DECL, a VAR_DECL or
   NULL_TREE.  Some target formats do not support arbitrary sections.  Do not
   define this macro in such cases.  */

#define ASM_OUTPUT_SECTION_NAME(F, DECL, NAME, RELOC) \
do {								\
  extern FILE *asm_out_text_file;				\
  if ((DECL) && TREE_CODE (DECL) == FUNCTION_DECL)		\
    fprintf (asm_out_text_file, "\t.section %s,\"ax\",@progbits\n", (NAME)); \
  else if ((DECL) && DECL_READONLY_SECTION (DECL, RELOC))	\
    fprintf (F, "\t.section %s,\"a\",@progbits\n", (NAME));	\
  else								\
    fprintf (F, "\t.section %s,\"aw\",@progbits\n", (NAME));	\
} while (0)

/* The following macro defines the format used to output the second
   operand of the .type assembler directive.  Different svr4 assemblers
   expect various different forms for this operand.  The one given here
   is just a default.  You may need to override it in your machine-
   specific tm.h file (depending upon the particulars of your assembler).  */

#define TYPE_OPERAND_FMT        "@%s"

/* Define the strings used for the special svr4 .type and .size directives.
   These strings generally do not vary from one system running svr4 to
   another, but if a given system (e.g. m88k running svr) needs to use
   different pseudo-op names for these, they may be overridden in the
   file which includes this one.  */

#undef TYPE_ASM_OP
#undef SIZE_ASM_OP
#define TYPE_ASM_OP	".type"
#define SIZE_ASM_OP	".size"

/* These macros generate the special .type and .size directives which
   are used to set the corresponding fields of the linker symbol table
   entries in an ELF object file under SVR4.  These macros also output
   the starting labels for the relevant functions/objects.  */

/* Write the extra assembler code needed to declare an object properly.  */

#undef ASM_DECLARE_OBJECT_NAME
#define ASM_DECLARE_OBJECT_NAME(FILE, NAME, DECL)			\
  do {									\
    fprintf (FILE, "\t%s\t ", TYPE_ASM_OP);				\
    assemble_name (FILE, NAME);						\
    putc (',', FILE);							\
    fprintf (FILE, TYPE_OPERAND_FMT, "object");				\
    putc ('\n', FILE);							\
    size_directive_output = 0;						\
    if (!flag_inhibit_size_directive && DECL_SIZE (DECL))		\
      {									\
	size_directive_output = 1;					\
	fprintf (FILE, "\t%s\t ", SIZE_ASM_OP);				\
	assemble_name (FILE, NAME);					\
	fprintf (FILE, ",%d\n",  int_size_in_bytes (TREE_TYPE (DECL)));	\
      }									\
    mips_declare_object (FILE, NAME, "", ":\n", 0);			\
  } while (0)

/* Output the size directive for a decl in rest_of_decl_compilation
   in the case where we did not do so before the initializer.
   Once we find the error_mark_node, we know that the value of
   size_directive_output was set
   by ASM_DECLARE_OBJECT_NAME when it was run for the same decl.  */

#undef ASM_FINISH_DECLARE_OBJECT
#define ASM_FINISH_DECLARE_OBJECT(FILE, DECL, TOP_LEVEL, AT_END)	 \
do {									 \
     char *name = XSTR (XEXP (DECL_RTL (DECL), 0), 0);			 \
     if (!flag_inhibit_size_directive && DECL_SIZE (DECL)		 \
         && ! AT_END && TOP_LEVEL					 \
	 && DECL_INITIAL (DECL) == error_mark_node			 \
	 && !size_directive_output)					 \
       {								 \
	 size_directive_output = 1;					 \
	 fprintf (FILE, "\t%s\t ", SIZE_ASM_OP);			 \
	 assemble_name (FILE, name);					 \
	 fprintf (FILE, ",%d\n", int_size_in_bytes (TREE_TYPE (DECL)));  \
       }								 \
   } while (0)

#define ASM_OUTPUT_DEF(FILE,LABEL1,LABEL2)                            \
 do { fputc ( '\t', FILE);                                            \
      assemble_name (FILE, LABEL1);                                   \
      fputs ( " = ", FILE);                                           \
      assemble_name (FILE, LABEL2);                                   \
      fputc ( '\n', FILE);                                            \
 } while (0)

/* Note about .weak vs. .weakext
   The mips native assemblers support .weakext, but not .weak.
   mips-elf gas supports .weak, but not .weakext.
   mips-elf gas has been changed to support both .weak and .weakext,
   but until that support is generally available, the 'if' below
   should serve. */

#define ASM_WEAKEN_LABEL(FILE,NAME) ASM_OUTPUT_WEAK_ALIAS(FILE,NAME,0)
#define ASM_OUTPUT_WEAK_ALIAS(FILE,NAME,VALUE)	\
 do {						\
  if (TARGET_GAS)                               \
      fputs ("\t.weak\t", FILE);		\
  else                                          \
      fputs ("\t.weakext\t", FILE);		\
  assemble_name (FILE, NAME);			\
  if (VALUE)					\
    {						\
      fputc (' ', FILE);			\
      assemble_name (FILE, VALUE);		\
    }						\
  fputc ('\n', FILE);				\
 } while (0)

#define MAKE_DECL_ONE_ONLY(DECL) (DECL_WEAK (DECL) = 1)
#undef UNIQUE_SECTION_P
#define UNIQUE_SECTION_P(DECL) (DECL_ONE_ONLY (DECL))
#define UNIQUE_SECTION(DECL,RELOC)					   \
do {									   \
  int len, size, sec;							   \
  char *name, *string, *prefix;						   \
  static char *prefixes[4][2] = {					   \
    { ".text.", ".gnu.linkonce.t." },					   \
    { ".rodata.", ".gnu.linkonce.r." },					   \
    { ".data.", ".gnu.linkonce.d." },					   \
    { ".sdata.", ".gnu.linkonce.s." }					   \
  };									   \
									   \
  name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (DECL));		   \
  size = int_size_in_bytes (TREE_TYPE (decl));				   \
									   \
  /* Determine the base section we are interested in:			   \
     0=text, 1=rodata, 2=data, 3=sdata.  */				   \
  if (TREE_CODE (DECL) == FUNCTION_DECL)				   \
    sec = 0;								   \
  else if ((TARGET_EMBEDDED_PIC || TARGET_MIPS16)			   \
      && TREE_CODE (decl) == STRING_CST					   \
      && !flag_writable_strings)					   \
    {									   \
      /* For embedded position independent code, put constant strings	   \
	 in the text section, because the data section is limited to	   \
	 64K in size.  For mips16 code, put strings in the text		   \
	 section so that a PC relative load instruction can be used to	   \
	 get their address.  */						   \
      sec = 0;								   \
    }									   \
  else if (TARGET_EMBEDDED_DATA)					   \
    {									   \
      /* For embedded applications, always put an object in read-only data \
	 if possible, in order to reduce RAM usage.  */			   \
									   \
      if (DECL_READONLY_SECTION (DECL, RELOC))				   \
	sec = 1;							   \
      else if (size > 0 && size <= mips_section_threshold)		   \
	sec = 3;							   \
      else								   \
	sec = 2;							   \
    }									   \
  else									   \
    {									   \
      /* For hosted applications, always put an object in small data if	   \
	 possible, as this gives the best performance.  */		   \
									   \
      if (size > 0 && size <= mips_section_threshold)			   \
	sec = 3;							   \
      else if (DECL_READONLY_SECTION (DECL, RELOC))			   \
	sec = 1;							   \
      else								   \
	sec = 2;							   \
    }									   \
									   \
  prefix = prefixes[sec][DECL_ONE_ONLY (DECL)];				   \
  len = strlen (name) + strlen (prefix);				   \
  string = alloca (len + 1);						   \
  sprintf (string, "%s%s", prefix, name);				   \
									   \
  DECL_SECTION_NAME (DECL) = build_string (len, string);		   \
} while (0)

/* Support the ctors/dtors and other sections.  */
 
/* 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    "\t.section\t.ctors,\"aw\""
#define DTORS_SECTION_ASM_OP    "\t.section\t.dtors,\"aw\""
 
/* A list of other sections which the compiler might be "in" at any
   given time.  */
#undef EXTRA_SECTIONS
#define EXTRA_SECTIONS in_sdata, in_rdata, in_ctors, in_dtors
 
#define INVOKE__main
#define NAME__MAIN "__gccmain"
#define SYMBOL__MAIN __gccmain

#undef EXTRA_SECTION_FUNCTIONS
#define EXTRA_SECTION_FUNCTIONS                                         \
  SECTION_FUNCTION_TEMPLATE(sdata_section, in_sdata, SDATA_SECTION_ASM_OP) \
  SECTION_FUNCTION_TEMPLATE(rdata_section, in_rdata, RDATA_SECTION_ASM_OP) \
  SECTION_FUNCTION_TEMPLATE(ctors_section, in_ctors, CTORS_SECTION_ASM_OP) \
  SECTION_FUNCTION_TEMPLATE(dtors_section, in_dtors, DTORS_SECTION_ASM_OP)

#define SECTION_FUNCTION_TEMPLATE(FN, ENUM, OP)                               \
void FN ()                                                            \
{                                                                     \
  if (in_section != ENUM)                                             \
    {                                                                 \
      fprintf (asm_out_file, "%s\n", OP);                             \
      in_section = ENUM;                                              \
    }                                                                 \
}


/* A C statement (sans semicolon) to output an element in the table of
   global constructors.  */
#define ASM_OUTPUT_CONSTRUCTOR(FILE,NAME)                             \
  do {                                                                \
    ctors_section ();                                                 \
    fprintf (FILE, "\t%s\t", TARGET_LONG64 ? ".dword" : ".word");     \
    assemble_name (FILE, NAME);                                       \
    fprintf (FILE, "\n");                                             \
  } while (0)


/* A C statement (sans semicolon) to output an element in the table of
   global destructors.  */
#define ASM_OUTPUT_DESTRUCTOR(FILE,NAME)                              \
  do {                                                                \
    dtors_section ();                                                 \
    fprintf (FILE, "\t%s\t", TARGET_LONG64 ? ".dword" : ".word");     \
    assemble_name (FILE, NAME);                                       \
    fprintf (FILE, "\n");                                             \
  } while (0)

#define CTOR_LIST_BEGIN                                 \
asm (CTORS_SECTION_ASM_OP);                             \
func_ptr __CTOR_LIST__[1] = { (func_ptr) (-1) }
 
#define CTOR_LIST_END                                   \
asm (CTORS_SECTION_ASM_OP);                             \
func_ptr __CTOR_END__[1] = { (func_ptr) 0 };
 
#define DTOR_LIST_BEGIN                                 \
asm (DTORS_SECTION_ASM_OP);                             \
func_ptr __DTOR_LIST__[1] = { (func_ptr) (-1) }

#define DTOR_LIST_END                                   \
asm (DTORS_SECTION_ASM_OP);                             \
func_ptr __DTOR_END__[1] = { (func_ptr) 0 };

/* Don't set the target flags, this is done by the linker script */
#undef LIB_SPEC
#define LIB_SPEC ""

#undef  STARTFILE_SPEC
#define STARTFILE_SPEC "crtbegin%O%s crt0%O%s"

#undef  ENDFILE_SPEC
#define ENDFILE_SPEC "crtend%O%s"