Re: [RFA] Allow casting of object pointers for method calls

[Michael Elizabeth Chastain <mec at shout dot net>]

Hi Elena,

> Michael, have you tested 5.1 + patch with older gcc? Any problems?
> If not I'll commit it right away.

It proofreads good and it tests good, like a patch should.

I hand-applied the patch to the 5.1 line.  The process of hand application
was good for proofreading.

I believe that my work in translating the patch from mainline to 5.1
branch is trivial and obvious.  This might be important because I don't
have an FSF assignment in place yet (the FSF has just sent me paperwork).
Andrew, is this an issue?

The patch touches only dwarf-2 support and only for the attribute form
DW_FORM_strp, plus it removes some support for the unsupported case
HOST_CHAR_BITS != 8.  The HOST_CHAR_BITS parts were in the original
patch in response to a comment from Andrew.

I tested the 5.1 line with 8 configurations:

  gcc 2.95.3, gcc 3.0.2, gcc HEAD, gcc gcc-3_0-branch
  -gstabs+, -gdwarf-2

The tables are here:

  http://www.shout.net/~mec/public_html/sunday/2001-12-06/index.html

The new gdb fixes the problem with gcc HEAD dwarf-2 and the results are
similar to the gcc 3.0.2 dwarf-2 and gcc gcc-3_0-branch dwarf2.  There
are no significant regressions with the other 7 tested configurations.
There are insignificant result transitions in gdb.c++/annota2.exp
and gdb.base/interrupt.exp.

I recomend this patch for commitment on the 5.1 branch.

Michael C

===

2001-11-12  Jakub Jelinek  <jakub@redhat.com>

	* dwarf2read.c (dwarf_str_buffer): New.
	(struct dwarf2_pinfo): Add dwarf_str_buffer and dwarf_str_size.
	(DWARF_STR_BUFFER, DWARF_STR_SIZE): Define.
	(dwarf2_has_info): Clear dwarf_str_offset.
	(dwarf2_build_psymtabs): Read .debug_str section if present.
	(dwarf2_build_psymtabs_hard): Save DWARF_STR_BUFFER and
	DWARF_STR_SIZE.
	(psymtab_to_symtab_1): Restore DWARF_STR_BUFFER and DWARF_STR_SIZE.
	(read_attribute): Handle DW_FORM_strp.
	(read_n_bytes, read_string): Remove HOST_CHAR_BIT != 8
	handling code.
	(read_indirect_string): New.
	(dump_die): Handle DW_FORM_strp.

Index: dwarf2read.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2read.c,v
retrieving revision 1.29
diff -c -3 -r1.29 dwarf2read.c
*** dwarf2read.c	2001/07/05 16:45:48	1.29
--- dwarf2read.c	2001/12/07 11:01:20
***************
*** 43,48 ****
--- 43,49 ----
  #include "bcache.h"
  #include <fcntl.h>
  #include "gdb_string.h"
+ #include "gdb_assert.h"
  #include <sys/types.h>
  
  #ifndef DWARF2_REG_TO_REGNUM
***************
*** 302,307 ****
--- 303,309 ----
  static char *dwarf_info_buffer;
  static char *dwarf_abbrev_buffer;
  static char *dwarf_line_buffer;
+ static char *dwarf_str_buffer;
  
  /* A zeroed version of a partial die for initialization purposes.  */
  static struct partial_die_info zeroed_partial_die;
***************
*** 383,388 ****
--- 385,398 ----
      /* Pointer to start of dwarf line buffer for the objfile.  */
  
      char *dwarf_line_buffer;
+ 
+     /* Pointer to start of dwarf string buffer for the objfile.  */
+ 
+     char *dwarf_str_buffer;
+ 
+     /* Size of dwarf string section for the objfile.  */
+ 
+     unsigned int dwarf_str_size;
    };
  
  #define PST_PRIVATE(p) ((struct dwarf2_pinfo *)(p)->read_symtab_private)
***************
*** 391,396 ****
--- 401,408 ----
  #define DWARF_ABBREV_BUFFER(p) (PST_PRIVATE(p)->dwarf_abbrev_buffer)
  #define DWARF_ABBREV_SIZE(p) (PST_PRIVATE(p)->dwarf_abbrev_size)
  #define DWARF_LINE_BUFFER(p) (PST_PRIVATE(p)->dwarf_line_buffer)
+ #define DWARF_STR_BUFFER(p)  (PST_PRIVATE(p)->dwarf_str_buffer)
+ #define DWARF_STR_SIZE(p)    (PST_PRIVATE(p)->dwarf_str_size)
  
  /* Maintain an array of referenced fundamental types for the current
     compilation unit being read.  For DWARF version 1, we have to construct
***************
*** 619,624 ****
--- 631,639 ----
  
  static char *read_string (bfd *, char *, unsigned int *);
  
+ static char *read_indirect_string (bfd *, char *, const struct comp_unit_head *,
+                                    unsigned int *);
+ 
  static unsigned long read_unsigned_leb128 (bfd *, char *, unsigned int *);
  
  static long read_signed_leb128 (bfd *, char *, unsigned int *);
***************
*** 791,796 ****
--- 806,812 ----
  dwarf2_has_info (bfd *abfd)
  {
    dwarf_info_offset = dwarf_abbrev_offset = dwarf_line_offset = 0;
+   dwarf_str_offset = 0;
    bfd_map_over_sections (abfd, dwarf2_locate_sections, NULL);
    if (dwarf_info_offset && dwarf_abbrev_offset)
      {
***************
*** 869,874 ****
--- 885,897 ----
  					   dwarf_line_offset,
  					   dwarf_line_size);
  
+   if (dwarf_str_offset)
+     dwarf_str_buffer = dwarf2_read_section (objfile,
+                                         dwarf_str_offset,
+                                         dwarf_str_size);
+   else
+     dwarf_str_buffer = NULL;
+ 
    if (mainline || objfile->global_psymbols.size == 0 ||
        objfile->static_psymbols.size == 0)
      {
***************
*** 1045,1050 ****
--- 1068,1075 ----
        DWARF_ABBREV_BUFFER (pst) = dwarf_abbrev_buffer;
        DWARF_ABBREV_SIZE (pst) = dwarf_abbrev_size;
        DWARF_LINE_BUFFER (pst) = dwarf_line_buffer;
+       DWARF_STR_BUFFER (pst) = dwarf_str_buffer;
+       DWARF_STR_SIZE (pst) = dwarf_str_size;
        baseaddr = ANOFFSET (objfile->section_offsets, SECT_OFF_TEXT (objfile));
  
        /* Store the function that reads in the rest of the symbol table */
***************
*** 1344,1349 ****
--- 1369,1376 ----
    dwarf_abbrev_buffer = DWARF_ABBREV_BUFFER (pst);
    dwarf_abbrev_size = DWARF_ABBREV_SIZE (pst);
    dwarf_line_buffer = DWARF_LINE_BUFFER (pst);
+   dwarf_str_buffer = DWARF_STR_BUFFER (pst);
+   dwarf_str_size = DWARF_STR_SIZE (pst);
    baseaddr = ANOFFSET (pst->section_offsets, SECT_OFF_TEXT (objfile));
    cu_header_offset = offset;
    info_ptr = dwarf_info_buffer + offset;
***************
*** 3358,3363 ****
--- 3385,3395 ----
        DW_STRING (attr) = read_string (abfd, info_ptr, &bytes_read);
        info_ptr += bytes_read;
        break;
+     case DW_FORM_strp:
+       DW_STRING (attr) = read_indirect_string (abfd, info_ptr, cu_header,
+ 	                                       &bytes_read);
+       info_ptr += bytes_read;
+       break;
      case DW_FORM_block:
        blk = dwarf_alloc_block ();
        blk->size = read_unsigned_leb128 (abfd, info_ptr, &bytes_read);
***************
*** 3410,3416 ****
        DW_UNSND (attr) = read_unsigned_leb128 (abfd, info_ptr, &bytes_read);
        info_ptr += bytes_read;
        break;
-     case DW_FORM_strp:
      case DW_FORM_indirect:
      default:
        error ("Dwarf Error: Cannot handle %s in DWARF reader.",
--- 3442,3447 ----
***************
*** 3597,3628 ****
  static char *
  read_n_bytes (bfd *abfd, char *buf, unsigned int size)
  {
!   /* If the size of a host char is 8 bits, we can return a pointer
!      to the buffer, otherwise we have to copy the data to a buffer
!      allocated on the temporary obstack.  */
! #if HOST_CHAR_BIT == 8
    return buf;
- #else
-   char *ret;
-   unsigned int i;
- 
-   ret = obstack_alloc (&dwarf2_tmp_obstack, size);
-   for (i = 0; i < size; ++i)
-     {
-       ret[i] = bfd_get_8 (abfd, (bfd_byte *) buf);
-       buf++;
-     }
-   return ret;
- #endif
  }
  
  static char *
  read_string (bfd *abfd, char *buf, unsigned int *bytes_read_ptr)
  {
!   /* If the size of a host char is 8 bits, we can return a pointer
!      to the string, otherwise we have to copy the string to a buffer
!      allocated on the temporary obstack.  */
! #if HOST_CHAR_BIT == 8
    if (*buf == '\0')
      {
        *bytes_read_ptr = 1;
--- 3628,3643 ----
  static char *
  read_n_bytes (bfd *abfd, char *buf, unsigned int size)
  {
!   /* Require host char == 8 bits.  Other parts of GDB already do this (findvar.c).  */
!   gdb_assert (HOST_CHAR_BIT == 8);
    return buf;
  }
  
  static char *
  read_string (bfd *abfd, char *buf, unsigned int *bytes_read_ptr)
  {
!   /* Require host char == 8 bits.  Other parts of GDB already do this (findvar.c).  */
!   gdb_assert (HOST_CHAR_BIT == 8);
    if (*buf == '\0')
      {
        *bytes_read_ptr = 1;
***************
*** 3630,3654 ****
      }
    *bytes_read_ptr = strlen (buf) + 1;
    return buf;
! #else
!   int byte;
!   unsigned int i = 0;
  
!   while ((byte = bfd_get_8 (abfd, (bfd_byte *) buf)) != 0)
      {
!       obstack_1grow (&dwarf2_tmp_obstack, byte);
!       i++;
!       buf++;
      }
!   if (i == 0)
      {
!       *bytes_read_ptr = 1;
        return NULL;
      }
!   obstack_1grow (&dwarf2_tmp_obstack, '\0');
!   *bytes_read_ptr = i + 1;
!   return obstack_finish (&dwarf2_tmp_obstack);
! #endif
  }
  
  static unsigned long
--- 3645,3675 ----
      }
    *bytes_read_ptr = strlen (buf) + 1;
    return buf;
! }
  
! static char *
! read_indirect_string (bfd *abfd, char *buf,
!                       const struct comp_unit_head *cu_header,
! 		      unsigned int *bytes_read_ptr)
! {
!   LONGEST str_offset = read_offset (abfd, buf, cu_header,
!                                     (int *) bytes_read_ptr);
!   if (dwarf_str_buffer == NULL)
      {
!       error ("DW_FORM_strp used without .debug_str section");
!       return NULL;
      }
! 
!   if (str_offset >= dwarf_str_size)
      {
!       error ("DW_FORM_strp pointing outside of .debug_str section");
        return NULL;
      }
! 
!   gdb_assert (HOST_CHAR_BIT == 8);
!   if (dwarf_str_buffer[str_offset] == '\0')
!     return NULL;
!   return dwarf_str_buffer + str_offset;
  }
  
  static unsigned long
***************
*** 5552,5557 ****
--- 5573,5579 ----
  	  fprintf (stderr, "constant: %ld", DW_UNSND (&die->attrs[i]));
  	  break;
  	case DW_FORM_string:
+ 	case DW_FORM_strp:
  	  fprintf (stderr, "string: \"%s\"",
  		   DW_STRING (&die->attrs[i])
  		   ? DW_STRING (&die->attrs[i]) : "");
***************
*** 5562,5569 ****
  	  else
  	    fprintf (stderr, "flag: FALSE");
  	  break;
- 	case DW_FORM_strp:	/* we do not support separate string
- 				   section yet */
  	case DW_FORM_indirect:	/* we do not handle indirect yet */
  	default:
  	  fprintf (stderr, "unsupported attribute form: %d.",
--- 5584,5589 ----