dbxout.c

gcc库的原代码,对编程有很大帮助.

/* Output dbx-format symbol table information from GNU compiler.
   Copyright (C) 1987, 88, 92, 93, 94, 1995 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.  */


/* Output dbx-format symbol table data.
   This consists of many symbol table entries, each of them
   a .stabs assembler pseudo-op with four operands:
   a "name" which is really a description of one symbol and its type,
   a "code", which is a symbol defined in stab.h whose name starts with N_,
   an unused operand always 0,
   and a "value" which is an address or an offset.
   The name is enclosed in doublequote characters.

   Each function, variable, typedef, and structure tag
   has a symbol table entry to define it.
   The beginning and end of each level of name scoping within
   a function are also marked by special symbol table entries.

   The "name" consists of the symbol name, a colon, a kind-of-symbol letter,
   and a data type number.  The data type number may be followed by
   "=" and a type definition; normally this will happen the first time
   the type number is mentioned.  The type definition may refer to
   other types by number, and those type numbers may be followed
   by "=" and nested definitions.

   This can make the "name" quite long.
   When a name is more than 80 characters, we split the .stabs pseudo-op
   into two .stabs pseudo-ops, both sharing the same "code" and "value".
   The first one is marked as continued with a double-backslash at the
   end of its "name".

   The kind-of-symbol letter distinguished function names from global
   variables from file-scope variables from parameters from auto
   variables in memory from typedef names from register variables.
   See `dbxout_symbol'.

   The "code" is mostly redundant with the kind-of-symbol letter
   that goes in the "name", but not entirely: for symbols located
   in static storage, the "code" says which segment the address is in,
   which controls how it is relocated.

   The "value" for a symbol in static storage
   is the core address of the symbol (actually, the assembler
   label for the symbol).  For a symbol located in a stack slot
   it is the stack offset; for one in a register, the register number.
   For a typedef symbol, it is zero.

   If DEBUG_SYMS_TEXT is defined, all debugging symbols must be
   output while in the text section.

   For more on data type definitions, see `dbxout_type'.  */

/* Include these first, because they may define MIN and MAX.  */
#include <stdio.h>
#include <errno.h>

#include "config.h"
#include "tree.h"
#include "rtl.h"
#include "flags.h"
#include "regs.h"
#include "insn-config.h"
#include "reload.h"
#include "defaults.h"
#include "output.h" /* ASM_OUTPUT_SOURCE_LINE may refer to sdb functions.  */

#ifndef errno
extern int errno;
#endif

#ifdef XCOFF_DEBUGGING_INFO
#include "xcoffout.h"
#endif

#ifndef ASM_STABS_OP
#define ASM_STABS_OP ".stabs"
#endif

#ifndef ASM_STABN_OP
#define ASM_STABN_OP ".stabn"
#endif

#ifndef DBX_TYPE_DECL_STABS_CODE
#define DBX_TYPE_DECL_STABS_CODE N_LSYM
#endif

#ifndef DBX_STATIC_CONST_VAR_CODE
#define DBX_STATIC_CONST_VAR_CODE N_FUN
#endif

#ifndef DBX_REGPARM_STABS_CODE
#define DBX_REGPARM_STABS_CODE N_RSYM
#endif

#ifndef DBX_REGPARM_STABS_LETTER
#define DBX_REGPARM_STABS_LETTER 'P'
#endif

/* This is used for parameters passed by invisible reference in a register.  */
#ifndef GDB_INV_REF_REGPARM_STABS_LETTER
#define GDB_INV_REF_REGPARM_STABS_LETTER 'a'
#endif

#ifndef DBX_MEMPARM_STABS_LETTER
#define DBX_MEMPARM_STABS_LETTER 'p'
#endif

#ifndef FILE_NAME_JOINER
#define FILE_NAME_JOINER "/"
#endif

/* Nonzero means if the type has methods, only output debugging
   information if methods are actually written to the asm file.  */

static int flag_minimal_debug = 1;

/* Nonzero if we have actually used any of the GDB extensions
   to the debugging format.  The idea is that we use them for the
   first time only if there's a strong reason, but once we have done that,
   we use them whenever convenient.  */

static int have_used_extensions = 0;

/* Number for the next N_SOL filename stabs label.  The number 0 is reserved
   for the N_SO filename stabs label.  */

static int source_label_number = 1;

char *getpwd ();

/* Typical USG systems don't have stab.h, and they also have
   no use for DBX-format debugging info.  */

#if defined (DBX_DEBUGGING_INFO) || defined (XCOFF_DEBUGGING_INFO)

#ifdef DEBUG_SYMS_TEXT
#define FORCE_TEXT text_section ();
#else
#define FORCE_TEXT
#endif

#if defined (USG) || defined (NO_STAB_H)
#include "gstab.h"  /* If doing DBX on sysV, use our own stab.h.  */
#else
#include <stab.h>  /* On BSD, use the system's stab.h.  */

/* This is a GNU extension we need to reference in this file.  */
#ifndef N_CATCH
#define N_CATCH 0x54
#endif
#endif /* not USG */

#ifdef __GNU_STAB__
#define STAB_CODE_TYPE enum __stab_debug_code
#else
#define STAB_CODE_TYPE int
#endif

/* 1 if PARM is passed to this function in memory.  */

#define PARM_PASSED_IN_MEMORY(PARM) \
 (GET_CODE (DECL_INCOMING_RTL (PARM)) == MEM)

/* A C expression for the integer offset value of an automatic variable
   (N_LSYM) having address X (an RTX).  */
#ifndef DEBUGGER_AUTO_OFFSET
#define DEBUGGER_AUTO_OFFSET(X) \
  (GET_CODE (X) == PLUS ? INTVAL (XEXP (X, 1)) : 0)
#endif

/* A C expression for the integer offset value of an argument (N_PSYM)
   having address X (an RTX).  The nominal offset is OFFSET.  */
#ifndef DEBUGGER_ARG_OFFSET
#define DEBUGGER_ARG_OFFSET(OFFSET, X) (OFFSET)
#endif

/* Stream for writing to assembler file.  */

static FILE *asmfile;

/* Last source file name mentioned in a NOTE insn.  */

static char *lastfile;

/* Current working directory.  */

static char *cwd;

enum typestatus {TYPE_UNSEEN, TYPE_XREF, TYPE_DEFINED};

/* Vector recording the status of describing C data types.
   When we first notice a data type (a tree node),
   we assign it a number using next_type_number.
   That is its index in this vector.
   The vector element says whether we have yet output
   the definition of the type.  TYPE_XREF says we have
   output it as a cross-reference only.  */

enum typestatus *typevec;

/* Number of elements of space allocated in `typevec'.  */

static int typevec_len;

/* In dbx output, each type gets a unique number.
   This is the number for the next type output.
   The number, once assigned, is in the TYPE_SYMTAB_ADDRESS field.  */

static int next_type_number;

/* In dbx output, we must assign symbol-blocks id numbers
   in the order in which their beginnings are encountered.
   We output debugging info that refers to the beginning and
   end of the ranges of code in each block
   with assembler labels LBBn and LBEn, where n is the block number.
   The labels are generated in final, which assigns numbers to the
   blocks in the same way.  */

static int next_block_number;

/* These variables are for dbxout_symbol to communicate to
   dbxout_finish_symbol.
   current_sym_code is the symbol-type-code, a symbol N_... define in stab.h.
   current_sym_value and current_sym_addr are two ways to address the
   value to store in the symtab entry.
   current_sym_addr if nonzero represents the value as an rtx.
   If that is zero, current_sym_value is used.  This is used
   when the value is an offset (such as for auto variables,
   register variables and parms).  */

static STAB_CODE_TYPE current_sym_code;
static int current_sym_value;
static rtx current_sym_addr;

/* Number of chars of symbol-description generated so far for the
   current symbol.  Used by CHARS and CONTIN.  */

static int current_sym_nchars;

/* Report having output N chars of the current symbol-description.  */

#define CHARS(N) (current_sym_nchars += (N))

/* Break the current symbol-description, generating a continuation,
   if it has become long.  */

#ifndef DBX_CONTIN_LENGTH
#define DBX_CONTIN_LENGTH 80
#endif

#if DBX_CONTIN_LENGTH > 0
#define CONTIN  \
  do {if (current_sym_nchars > DBX_CONTIN_LENGTH) dbxout_continue ();} while (0)
#else
#define CONTIN
#endif

void dbxout_types ();
void dbxout_args ();
void dbxout_symbol ();
static void dbxout_type_name ();
static void dbxout_type ();
static void dbxout_typedefs ();
static void dbxout_symbol_name ();
static void dbxout_symbol_location ();
static void dbxout_prepare_symbol ();
static void dbxout_finish_symbol ();
static void dbxout_continue ();
static void print_int_cst_octal ();
static void print_octal ();

#if 0 /* Not clear we will actually need this.  */

/* Return the absolutized filename for the given relative
   filename.  Note that if that filename is already absolute, it may
   still be returned in a modified form because this routine also
   eliminates redundant slashes and single dots and eliminates double
   dots to get a shortest possible filename from the given input
   filename.  The absolutization of relative filenames is made by
   assuming that the given filename is to be taken as relative to
   the first argument (cwd) or to the current directory if cwd is
   NULL.  */

static char *
abspath (rel_filename)
     char *rel_filename;
{
  /* Setup the current working directory as needed.  */
  char *abs_buffer
    = (char *) alloca (strlen (cwd) + strlen (rel_filename) + 1);
  char *endp = abs_buffer;
  char *outp, *inp;
  char *value;

  /* Copy the filename (possibly preceded by the current working
     directory name) into the absolutization buffer.  */

  {
    char *src_p;

    if (rel_filename[0] != '/')
      {
        src_p = cwd;
        while (*endp++ = *src_p++)
          continue;
        *(endp-1) = '/';        		/* overwrite null */
      }
    src_p = rel_filename;
    while (*endp++ = *src_p++)
      continue;
    if (endp[-1] == '/')
      *endp = '\0';

  /* Now make a copy of abs_buffer into abs_buffer, shortening the
     filename (by taking out slashes and dots) as we go.  */

  outp = inp = abs_buffer;
  *outp++ = *inp++;        	/* copy first slash */
  for (;;)
    {
      if (!inp[0])
        break;
      else if (inp[0] == '/' && outp[-1] == '/')
        {
          inp++;
          continue;
        }
      else if (inp[0] == '.' && outp[-1] == '/')
        {
          if (!inp[1])
                  break;
          else if (inp[1] == '/')
            {
                    inp += 2;
                    continue;
            }
          else if ((inp[1] == '.') && (inp[2] == 0 || inp[2] == '/'))
            {
                    inp += (inp[2] == '/') ? 3 : 2;
                    outp -= 2;
                    while (outp >= abs_buffer && *outp != '/')
              	outp--;
                    if (outp < abs_buffer)
                {
                  /* Catch cases like /.. where we try to backup to a
                     point above the absolute root of the logical file
                     system.  */

              	  fprintf (stderr, "%s: invalid file name: %s\n",
			   pname, rel_filename);
              	  exit (1);
              	}
                    *++outp = '\0';
                    continue;
            }
        }
      *outp++ = *inp++;
    }

  /* On exit, make sure that there is a trailing null, and make sure that
     the last character of the returned string is *not* a slash.  */

  *outp = '\0';
  if (outp[-1] == '/')
    *--outp  = '\0';

  /* Make a copy (in the heap) of the stuff left in the absolutization
     buffer and return a pointer to the copy.  */

  value = (char *) oballoc (strlen (abs_buffer) + 1);
  strcpy (value, abs_buffer);
  return value;
}
#endif /* 0 */

/* At the beginning of compilation, start writing the symbol table.
   Initialize `typevec' and output the standard data types of C.  */

void
dbxout_init (asm_file, input_file_name, syms)
     FILE *asm_file;
     char *input_file_name;
     tree syms;
{
  char ltext_label_name[100];

  asmfile = asm_file;

  typevec_len = 100;
  typevec = (enum typestatus *) xmalloc (typevec_len * sizeof typevec[0]);
  bzero ((char *) typevec, typevec_len * sizeof typevec[0]);

  /* Convert Ltext into the appropriate format for local labels in case
     the system doesn't insert underscores in front of user generated
     labels.  */
  ASM_GENERATE_INTERNAL_LABEL (ltext_label_name, "Ltext", 0);

  /* Put the current working directory in an N_SO symbol.  */
#ifndef DBX_WORKING_DIRECTORY /* Only some versions of DBX want this,
				 but GDB always does.  */
  if (use_gnu_debug_info_extensions)
#endif
    {
      if (!cwd && (cwd = getpwd ()) && (!*cwd || cwd[strlen (cwd) - 1] != '/'))
	{
	  char *wdslash = xmalloc (strlen (cwd) + sizeof (FILE_NAME_JOINER));
	  sprintf (wdslash, "%s%s", cwd, FILE_NAME_JOINER);
	  cwd = wdslash;
	}
      if (cwd)
	{
#ifdef DBX_OUTPUT_MAIN_SOURCE_DIRECTORY
	  DBX_OUTPUT_MAIN_SOURCE_DIRECTORY (asmfile, cwd);
#else /* no DBX_OUTPUT_MAIN_SOURCE_DIRECTORY */
	  fprintf (asmfile, "%s ", ASM_STABS_OP);