dbxout.c

这是完整的gcc源代码

/* Output dbx-format symbol table information from GNU compiler.
   Copyright (C) 1987, 1988 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 1, 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, 675 Mass Ave, Cambridge, MA 02139, 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 "config.h"
#include "tree.h"
#include "rtl.h"
#include "flags.h"
#include <stdio.h>
#include <sys/param.h>
#include <errno.h>

#ifndef errno
extern int errno;
#endif

/* Virtually every UN*X system now in common use (except for pre-4.3-tahoe
   BSD systems) now provides getcwd as called for by POSIX.  Allow for
   the few exceptions to the general rule here.  */

#if !(defined (USG) || defined (VMS))
extern char *getwd ();
#define getcwd(buf,len) getwd(buf)
#define GUESSPATHLEN (MAXPATHLEN + 1)
#else /* (defined (USG) || defined (VMS)) */
extern char *getcwd ();
/* We actually use this as a starting point, not a limit.  */
#define GUESSPATHLEN 100
#endif /* (defined (USG) || defined (VMS)) */

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

#ifdef DBX_DEBUGGING_INFO

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

#ifdef USG
#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.  */
#endif /* not USG */

/* Stream for writing to assembler file.  */

static FILE *asmfile;

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 int 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_tags ();
void dbxout_args ();
void dbxout_symbol ();
static void dbxout_type_name ();
static void dbxout_type ();
static void dbxout_finish_symbol ();
static void dbxout_continue ();

/* 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)
     FILE *asm_file;
     char *input_file_name;
{
  asmfile = asm_file;

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

  /* Put the current working directory in an N_SO symbol.  */
  {
    static char *cwd;
    static enum {not_gotten, gotten, error_getting} cwd_status = not_gotten;
    int size;

    if (cwd_status == not_gotten)
      {
	char *value;

	/* Read the working directory, avoiding arbitrary limit.  */
	size = GUESSPATHLEN;
	while (1)
	  {
	    cwd = (char *) xmalloc (size);
	    value = getcwd (cwd, size);
	    if (value != 0 || errno != ERANGE)
	      break;
	    free (cwd);
	    size *= 2;
	  }

	if (value != 0)
	  cwd_status = gotten;
	else
	  cwd_status = error_getting;
      }

    if (cwd_status == gotten)
      {
#ifdef ASM_OUTPUT_MAIN_SOURCE_DIRECTORY
	ASM_OUTPUT_MAIN_SOURCE_DIRECTORY (asmfile, cwd);
#else /* no ASM_OUTPUT_MAIN_SOURCE_DIRECTORY */
	fprintf (asmfile, "%s \"%s/\",%d,0,0,%s\n", ".stabs",
		 cwd, N_SO, "Ltext");
#endif /* no ASM_OUTPUT_MAIN_SOURCE_DIRECTORY */
      }
  }

  /* Used to put `Ltext:' before the reference, but that loses on sun 4.  */
  fprintf (asmfile,
	   "\t.stabs \"%s\",%d,0,0,Ltext\nLtext:\n",
	   input_file_name, N_SO);

  next_type_number = 1;
  next_block_number = 2;

  /* Make sure that types `int' and `char' have numbers 1 and 2.
     Definitions of other integer types will refer to those numbers.  */

  dbxout_symbol (TYPE_NAME (integer_type_node), 0);
  dbxout_symbol (TYPE_NAME (char_type_node), 0);

  /* Get all permanent types not yet gotten, and output them.  */

  dbxout_types (get_permanent_types ());
}

/* Continue a symbol-description that gets too big.
   End one symbol table entry with a double-backslash
   and start a new one, eventually producing something like
   .stabs "start......\\",code,0,value
   .stabs "...rest",code,0,value   */

static void
dbxout_continue ()
{
#ifdef DBX_CONTIN_CHAR
  fprintf (asmfile, "%c", DBX_CONTIN_CHAR);
#else
  fprintf (asmfile, "\\\\");
#endif
  dbxout_finish_symbol ();
  fprintf (asmfile, ".stabs \"");
  current_sym_nchars = 0;
}

/* Output a reference to a type.  If the type has not yet been
   described in the dbx output, output its definition now.
   For a type already defined, just refer to its definition
   using the type number.

   If FULL is nonzero, and the type has been described only with
   a forward-reference, output the definition now.
   If FULL is zero in this case, just refer to the forward-reference
   using the number previously allocated.  */

static void
dbxout_type (type, full)
     tree type;
     int full;
{
  register tree tem;

  /* If there was an input error and we don't really have a type,
     avoid crashing and write something that is at least valid
     by assuming `int'.  */
  if (type == error_mark_node)
    type = integer_type_node;
  else
    type = TYPE_MAIN_VARIANT (type);

  if (TYPE_SYMTAB_ADDRESS (type) == 0)
    {
      /* Type has no dbx number assigned.  Assign next available number.  */
      TYPE_SYMTAB_ADDRESS (type) = next_type_number++;

      /* Make sure type vector is long enough to record about this type.  */

      if (next_type_number == typevec_len)
	{
	  typevec = (enum typestatus *) xrealloc (typevec, typevec_len * 2 * sizeof typevec[0]);
	  bzero (typevec + typevec_len, typevec_len * sizeof typevec[0]);
	  typevec_len *= 2;
	}
    }

  /* Output the number of this type, to refer to it.  */
  fprintf (asmfile, "%d", TYPE_SYMTAB_ADDRESS (type));
  CHARS (3);

  /* If this type's definition has been output or is now being output,
     that is all.  */

  switch (typevec[TYPE_SYMTAB_ADDRESS (type)])
    {
    case TYPE_UNSEEN:
      break;
    case TYPE_XREF:
      if (! full)
	return;
      break;
    case TYPE_DEFINED:
      return;
    }

#ifdef DBX_NO_XREFS
  /* For systems where dbx output does not allow the `=xsNAME:' syntax,
     leave the type-number completely undefined rather than output
     a cross-reference.  */
  if (TREE_CODE (type) == RECORD_TYPE || TREE_CODE (type) == UNION_TYPE
      || TREE_CODE (type) == ENUMERAL_TYPE)

    if ((TYPE_NAME (type) != 0 && !full)
	|| TYPE_SIZE (type) == 0)
      {
	typevec[TYPE_SYMTAB_ADDRESS (type)] = TYPE_XREF;
	return;
      }
#endif

  /* Output a definition now.  */

  fprintf (asmfile, "=");
  CHARS (1);

  /* Mark it as defined, so that if it is self-referent
     we will not get into an infinite recursion of definitions.  */

  typevec[TYPE_SYMTAB_ADDRESS (type)] = TYPE_DEFINED;

  switch (TREE_CODE (type))
    {
    case VOID_TYPE:
      /* For a void type, just define it as itself; ie, "5=5".
	 This makes us consider it defined
	 without saying what it is.  The debugger will make it
	 a void type when the reference is seen, and nothing will
	 ever override that default.  */
      fprintf (asmfile, "%d", TYPE_SYMTAB_ADDRESS (type));
      CHARS (3);
      break;

    case INTEGER_TYPE:
      if (type == char_type_node && ! TREE_UNSIGNED (type))
	/* Output the type `char' as a subrange of itself!
	   I don't understand this definition, just copied it
	   from the output of pcc.  */
	fprintf (asmfile, "r2;0;127;");
      else
	/* Output other integer types as subranges of `int'.  */
	fprintf (asmfile, "r1;%d;%d;",
		 TREE_INT_CST_LOW (TYPE_MIN_VALUE (type)),
		 TREE_INT_CST_LOW (TYPE_MAX_VALUE (type)));
      CHARS (25);
      break;

    case REAL_TYPE:
      /* This must be magic.  */
      fprintf (asmfile, "r1;%d;0;",
	       TREE_INT_CST_LOW (size_in_bytes (type)));
      CHARS (16);
      break;

    case ARRAY_TYPE:
      /* Output "a" followed by a range type definition
	 for the index type of the array
	 followed by a reference to the target-type.
	 ar1;0;N;M for an array of type M and size N.  */
      fprintf (asmfile, "ar1;0;%d;",
	       (TYPE_DOMAIN (type)
		? TREE_INT_CST_LOW (TYPE_MAX_VALUE (TYPE_DOMAIN (type)))
	        : -1));
      CHARS (17);
      dbxout_type (TREE_TYPE (type), 0);
      break;

    case RECORD_TYPE:
    case UNION_TYPE:
      /* Output a structure type.  */
      if ((TYPE_NAME (type) != 0 && !full)
	  || TYPE_SIZE (type) == 0)
	{
	  /* If the type is just a cross reference, output one