Re: [RFA]: Add misc_obstack to object files.

Re: [RFA]: Add misc_obstack to object files.

[Michael Elizabeth Chastain]

I'd like to throw my hat in the ring, too.  I spent a whole weekend 
several months ago changing the type of all the section offset tables.
I wound up with a 3000 line patch that I didn't even try to get
approved.  (I was working on PR gdb/29, "gdb has fixed size MAX_SECTIONS").
So I care about section offset tables.

> I'm just adding a bin for colored paper, so people will put that stuff
> in there instead in the first place, and it will be plainly clear that
> they are supposed to be doing so.

So you don't have a manifestation of a bug in your hand; rather, you are
cleaning up something that is broken.  That's fine.  I am comfortable
with your rationale, now that I know what it is.

I see three specific problems:

. in lines 1984-1993 of symfile.c, you change the "psymtab" pointer from
  psymbol_obstack to misc_obstack.  It's not obvious why this structure
  is on misc_obstack.  Since it's not obvious, a comment would help.

. as Elena mentioned, there are other files which allocate section
  offsets on the psymbol_obstack.  I see somread.c in particular.
  
  Right now it's difficult to test somread.c, because even if you have
  access to hppa hardware, FSF gdb does not link for that configuration
  (PR gdb/63).  If you can't test it, and you don't want to go for a
  blind patch to somread.c, then I think that a FIXME comment would be
  appropriate, to explain to the next hpux maintainer why this target
  allocates section_offsets on psymbol_objstack when other targets use
  misc_obstack.  Something like: "FIXME: this should be misc_obstack,
  same as symfile.c, but I can't test this file so I'm leaving it as
  psymbol_obstack, which ought to continue working for now".

. the new comment on lines 121-137 of objfiles.c is not true yet,
  even after applying your patch.  For example, dbxread.c puts
  DBX_STRINGTAB on psymbol_obstack.  So I challenge your claim
  "All the stuff in objfile that was on the psymbol obstack,
  but didnt' belong, is in the misc obstack ...".

> The only thing even related to psymtabs there is the fact that they
> psymtab structure itself is allocated on the misc obstack, since it
> isn't a partial symbol either. It's a partial symbol table structure,
> containing pointers to partial symbols. 

If you put this in a comment, that would answer my first question
(which might be the same as Elena's question about an extraneous patch
fragment, but I don't know what fragment Elena is referring to).

> I could do them all now if it helps, but it'll make the patch bigger.

I like it better this way, one structure at a time.  I think that
Elena's looking for some sense of whether this is a standalone patch
or part of a bigger series -- not one big patch.

Here are the reasons that I prefer series:

. It's easier to proof-read one concept at a time.

. It's easier to read the first "proof of concept" when there's only
  one structure in it, rather than old structures.

. If something breaks in the future, and I need to binary-search old
  versions of gdb, this improves the granularity that I can resolve the
  bug too.  This is important for symbol table patches as a bug can
  manifest subtly (e.g. lookup_symbol bug -> infinite loop in "maint"
  command when running on an inferior copy of gdb).

Basically there are two different ideas here.  First there is the idea of
what should actually be in gdb.  I'm comfortable with your vision there.
Second there is the idea of structuring one's work so that other people
can deduce that it actually implements the concept (including checking
for implementation bugs).

Just my two cents.  I'll try not to write again, as Elena is the
maintainer here.

Michael

[RFA]: Add misc_obstack to object files.

[Daniel Berlin]

This way, we stop putting things in the psymbol_obstack that don't
belong.  

2001-05-27  Daniel Berlin  <dan@cgsoftware.com>

	* symfile.c (default_symfile_offsets): Allocate in misc_obstack.
	(reread_symbols): Handle misc_obstack too, and use it where
	psymbol_obstack didn't belong. 
	(allocate_psymtab): Ditto.

	* objfiles.c (add_to_objfile_sections):  Use misc_obstack, not psymbol_obstack.
	(build_objfile_section_table): Ditto.
	(free_objfile): Free the misc_obstack.
	(allocate_objfile): Setup misc_obstack too.

	* objfiles.h: Add misc_obstack to object file.

Index: symfile.c
===================================================================
RCS file: /cvs/src/src/gdb/symfile.c,v
retrieving revision 1.32
diff -c -3 -p -w -B -b -r1.32 symfile.c
*** symfile.c	2001/05/10 15:33:21	1.32
--- symfile.c	2001/05/29 17:27:51
*************** default_symfile_offsets (struct objfile 
*** 500,506 ****
  
    objfile->num_sections = SECT_OFF_MAX;
    objfile->section_offsets = (struct section_offsets *)
!     obstack_alloc (&objfile->psymbol_obstack, SIZEOF_SECTION_OFFSETS);
    memset (objfile->section_offsets, 0, SIZEOF_SECTION_OFFSETS);
  
    /* Now calculate offsets for section that were specified by the
--- 500,506 ----
  
    objfile->num_sections = SECT_OFF_MAX;
    objfile->section_offsets = (struct section_offsets *)
!     obstack_alloc (&objfile->misc_obstack, SIZEOF_SECTION_OFFSETS);
    memset (objfile->section_offsets, 0, SIZEOF_SECTION_OFFSETS);
  
    /* Now calculate offsets for section that were specified by the
*************** reread_symbols (void)
*** 1679,1684 ****
--- 1679,1685 ----
  
  	      /* Free the obstacks for non-reusable objfiles */
  	      free_bcache (&objfile->psymbol_cache);
+ 	      obstack_free (&objfile->misc_obstack, 0);
  	      obstack_free (&objfile->psymbol_obstack, 0);
  	      obstack_free (&objfile->symbol_obstack, 0);
  	      obstack_free (&objfile->type_obstack, 0);
*************** reread_symbols (void)
*** 1704,1709 ****
--- 1705,1712 ----
  	         it is empty.  */
  	      obstack_specify_allocation (&objfile->psymbol_cache.cache, 0, 0,
  					  xmalloc, xfree);
+ 	      obstack_specify_allocation (&objfile->misc_obstack, 0, 0,
+ 					  xmalloc, xfree);
  	      obstack_specify_allocation (&objfile->psymbol_obstack, 0, 0,
  					  xmalloc, xfree);
  	      obstack_specify_allocation (&objfile->symbol_obstack, 0, 0,
*************** reread_symbols (void)
*** 1719,1725 ****
  	      /* We use the same section offsets as from last time.  I'm not
  	         sure whether that is always correct for shared libraries.  */
  	      objfile->section_offsets = (struct section_offsets *)
! 		obstack_alloc (&objfile->psymbol_obstack, SIZEOF_SECTION_OFFSETS);
  	      memcpy (objfile->section_offsets, offsets, SIZEOF_SECTION_OFFSETS);
  	      objfile->num_sections = num_offsets;
  
--- 1722,1728 ----
  	      /* We use the same section offsets as from last time.  I'm not
  	         sure whether that is always correct for shared libraries.  */
  	      objfile->section_offsets = (struct section_offsets *)
! 		obstack_alloc (&objfile->misc_obstack, SIZEOF_SECTION_OFFSETS);
  	      memcpy (objfile->section_offsets, offsets, SIZEOF_SECTION_OFFSETS);
  	      objfile->num_sections = num_offsets;
  
*************** allocate_psymtab (char *filename, struct
*** 1981,1993 ****
        objfile->free_psymtabs = psymtab->next;
      }
    else
!     psymtab = (struct partial_symtab *)
!       obstack_alloc (&objfile->psymbol_obstack,
! 		     sizeof (struct partial_symtab));
  
    memset (psymtab, 0, sizeof (struct partial_symtab));
!   psymtab->filename = obsavestring (filename, strlen (filename),
! 				    &objfile->psymbol_obstack);
    psymtab->symtab = NULL;
  
    /* Prepend it to the psymtab list for the objfile it belongs to.
--- 1984,1993 ----
        objfile->free_psymtabs = psymtab->next;
      }
    else
!     psymtab = (struct partial_symtab *) obstack_alloc (&objfile->misc_obstack, sizeof (struct partial_symtab));
  
    memset (psymtab, 0, sizeof (struct partial_symtab));
!   psymtab->filename = obsavestring (filename, strlen(filename), &objfile->misc_obstack);
    psymtab->symtab = NULL;
  
    /* Prepend it to the psymtab list for the objfile it belongs to.
Index: objfiles.c
===================================================================
RCS file: /cvs/src/src/gdb/objfiles.c,v
retrieving revision 1.15
diff -c -3 -p -w -B -b -r1.15 objfiles.c
*** objfiles.c	2001/03/06 08:21:11	1.15
--- objfiles.c	2001/05/29 17:27:57
*************** add_to_objfile_sections (bfd *abfd, sec_
*** 96,102 ****
    section.ovly_mapped = 0;
    section.addr = bfd_section_vma (abfd, asect);
    section.endaddr = section.addr + bfd_section_size (abfd, asect);
!   obstack_grow (&objfile->psymbol_obstack, (char *) &section, sizeof (section));
    objfile->sections_end = (struct obj_section *) (((unsigned long) objfile->sections_end) + 1);
  }
  
--- 96,102 ----
    section.ovly_mapped = 0;
    section.addr = bfd_section_vma (abfd, asect);
    section.endaddr = section.addr + bfd_section_size (abfd, asect);
!   obstack_grow (&objfile->misc_obstack, (char *) &section, sizeof (section));
    objfile->sections_end = (struct obj_section *) (((unsigned long) objfile->sections_end) + 1);
  }
  
*************** build_objfile_section_table (struct objf
*** 121,134 ****
  {
    /* objfile->sections can be already set when reading a mapped symbol
       file.  I believe that we do need to rebuild the section table in
!      this case (we rebuild other things derived from the bfd), but we
!      can't free the old one (it's in the psymbol_obstack).  So we just
!      waste some memory.  */
  
    objfile->sections_end = 0;
    bfd_map_over_sections (objfile->obfd, add_to_objfile_sections, (char *) objfile);
    objfile->sections = (struct obj_section *)
!     obstack_finish (&objfile->psymbol_obstack);
    objfile->sections_end = objfile->sections + (unsigned long) objfile->sections_end;
    return (0);
  }
--- 121,137 ----
  {
    /* objfile->sections can be already set when reading a mapped symbol
       file.  I believe that we do need to rebuild the section table in
!      this case (we rebuild other things derived from the bfd).
!      DJB - 05-27-2001 
!      It's in the misc_obstack now, feel free to do what you need to.
!      All the stuff in objfile that was on the psymbol obstack, but didnt' belong, is in the misc obstack, which 
!      I think is all the stuff you want to blow away anyway.
!      */
  
    objfile->sections_end = 0;
    bfd_map_over_sections (objfile->obfd, add_to_objfile_sections, (char *) objfile);
    objfile->sections = (struct obj_section *)
!     obstack_finish (&objfile->misc_obstack);
    objfile->sections_end = objfile->sections + (unsigned long) objfile->sections_end;
    return (0);
  }
*************** allocate_objfile (bfd *abfd, int flags)
*** 188,193 ****
--- 191,198 ----
  	      /* Update pointers to functions to *our* copies */
  	      obstack_chunkfun (&objfile->psymbol_cache.cache, xmmalloc);
  	      obstack_freefun (&objfile->psymbol_cache.cache, mfree);
+ 	      obstack_chunkfun (&objfile->misc_obstack, xmmalloc);
+ 	      obstack_freefun (&objfile->misc_obstack, mfree);
  	      obstack_chunkfun (&objfile->psymbol_obstack, xmmalloc);
  	      obstack_freefun (&objfile->psymbol_obstack, mfree);
  	      obstack_chunkfun (&objfile->symbol_obstack, xmmalloc);
*************** allocate_objfile (bfd *abfd, int flags)
*** 218,223 ****
--- 223,231 ----
  	      obstack_specify_allocation_with_arg (&objfile->psymbol_cache.cache,
  						   0, 0, xmmalloc, mfree,
  						   objfile->md);
+ 	      obstack_specify_allocation_with_arg (&objfile->misc_obstack,
+ 						   0, 0, xmmalloc, mfree,
+ 						   objfile->md);
  	      obstack_specify_allocation_with_arg (&objfile->psymbol_obstack,
  						   0, 0, xmmalloc, mfree,
  						   objfile->md);
*************** allocate_objfile (bfd *abfd, int flags)
*** 264,269 ****
--- 272,279 ----
        objfile->md = NULL;
        obstack_specify_allocation (&objfile->psymbol_cache.cache, 0, 0,
  				  xmalloc, xfree);
+       obstack_specify_allocation (&objfile->misc_obstack, 0, 0, xmalloc,
+ 				  xfree);
        obstack_specify_allocation (&objfile->psymbol_obstack, 0, 0, xmalloc,
  				  xfree);
        obstack_specify_allocation (&objfile->symbol_obstack, 0, 0, xmalloc,
*************** free_objfile (struct objfile *objfile)
*** 475,480 ****
--- 485,491 ----
  	mfree (objfile->md, objfile->static_psymbols.list);
        /* Free the obstacks for non-reusable objfiles */
        free_bcache (&objfile->psymbol_cache);
+       obstack_free (&objfile->misc_obstack, 0);
        obstack_free (&objfile->psymbol_obstack, 0);
        obstack_free (&objfile->symbol_obstack, 0);
        obstack_free (&objfile->type_obstack, 0);
Index: objfiles.h
===================================================================
RCS file: /cvs/src/src/gdb/objfiles.h,v
retrieving revision 1.8
diff -c -3 -p -w -B -b -r1.8 objfiles.h
*** objfiles.h	2001/03/06 08:21:11	1.8
--- objfiles.h	2001/05/29 17:28:00
*************** struct objfile
*** 269,274 ****
--- 269,275 ----
      /* Obstacks to hold objects that should be freed when we load a new symbol
         table from this object file. */
  
+     struct obstack misc_obstack;	/* Misc stuff */
      struct obstack psymbol_obstack;	/* Partial symbols */
      struct obstack symbol_obstack;	/* Full symbols */
      struct obstack type_obstack;	/* Types */

-- 
"I used to be a narrator for bad mimes.
"-Steven Wright

Re: [RFA]: Add misc_obstack to object files.

[Elena Zannoni]

Daniel Berlin writes:
 > 
 > This way, we stop putting things in the psymbol_obstack that don't
 > belong.  
 > 

Dan, can you elaborate a bit on why we need this? Why are you removing
the partial symbol table from the psymbol_objstack? Was this intended?
There are several other things that get allocated on the
psymbol_objstack, for instance look in xcoffread.c, somread.c,
etc. Why just remove the section offset stuff?

If your intent was to change the allocation of the section offset
information, from psymbol_obstack to misc_obstack, why not modify also
the same allocations done in xcoffread.c, elfread.c, somread.c?

Thanks
Elena


 > 2001-05-27  Daniel Berlin  <dan@cgsoftware.com>
 > 
 > 	* symfile.c (default_symfile_offsets): Allocate in misc_obstack.
 > 	(reread_symbols): Handle misc_obstack too, and use it where
 > 	psymbol_obstack didn't belong. 
 > 	(allocate_psymtab): Ditto.
 > 
 > 	* objfiles.c (add_to_objfile_sections):  Use misc_obstack, not psymbol_obstack.
 > 	(build_objfile_section_table): Ditto.
 > 	(free_objfile): Free the misc_obstack.
 > 	(allocate_objfile): Setup misc_obstack too.
 > 
 > 	* objfiles.h: Add misc_obstack to object file.
 > 
 > Index: symfile.c
 > ===================================================================
 > RCS file: /cvs/src/src/gdb/symfile.c,v
 > retrieving revision 1.32
 > diff -c -3 -p -w -B -b -r1.32 symfile.c
 > *** symfile.c	2001/05/10 15:33:21	1.32
 > --- symfile.c	2001/05/29 17:27:51
 > *************** default_symfile_offsets (struct objfile 
 > *** 500,506 ****
 >   
 >     objfile->num_sections = SECT_OFF_MAX;
 >     objfile->section_offsets = (struct section_offsets *)
 > !     obstack_alloc (&objfile->psymbol_obstack, SIZEOF_SECTION_OFFSETS);
 >     memset (objfile->section_offsets, 0, SIZEOF_SECTION_OFFSETS);
 >   
 >     /* Now calculate offsets for section that were specified by the
 > --- 500,506 ----
 >   
 >     objfile->num_sections = SECT_OFF_MAX;
 >     objfile->section_offsets = (struct section_offsets *)
 > !     obstack_alloc (&objfile->misc_obstack, SIZEOF_SECTION_OFFSETS);
 >     memset (objfile->section_offsets, 0, SIZEOF_SECTION_OFFSETS);
 >   
 >     /* Now calculate offsets for section that were specified by the
 > *************** reread_symbols (void)
 > *** 1679,1684 ****
 > --- 1679,1685 ----
 >   
 >   	      /* Free the obstacks for non-reusable objfiles */
 >   	      free_bcache (&objfile->psymbol_cache);
 > + 	      obstack_free (&objfile->misc_obstack, 0);
 >   	      obstack_free (&objfile->psymbol_obstack, 0);
 >   	      obstack_free (&objfile->symbol_obstack, 0);
 >   	      obstack_free (&objfile->type_obstack, 0);
 > *************** reread_symbols (void)
 > *** 1704,1709 ****
 > --- 1705,1712 ----
 >   	         it is empty.  */
 >   	      obstack_specify_allocation (&objfile->psymbol_cache.cache, 0, 0,
 >   					  xmalloc, xfree);
 > + 	      obstack_specify_allocation (&objfile->misc_obstack, 0, 0,
 > + 					  xmalloc, xfree);
 >   	      obstack_specify_allocation (&objfile->psymbol_obstack, 0, 0,
 >   					  xmalloc, xfree);
 >   	      obstack_specify_allocation (&objfile->symbol_obstack, 0, 0,
 > *************** reread_symbols (void)
 > *** 1719,1725 ****
 >   	      /* We use the same section offsets as from last time.  I'm not
 >   	         sure whether that is always correct for shared libraries.  */
 >   	      objfile->section_offsets = (struct section_offsets *)
 > ! 		obstack_alloc (&objfile->psymbol_obstack, SIZEOF_SECTION_OFFSETS);
 >   	      memcpy (objfile->section_offsets, offsets, SIZEOF_SECTION_OFFSETS);
 >   	      objfile->num_sections = num_offsets;
 >   
 > --- 1722,1728 ----
 >   	      /* We use the same section offsets as from last time.  I'm not
 >   	         sure whether that is always correct for shared libraries.  */
 >   	      objfile->section_offsets = (struct section_offsets *)
 > ! 		obstack_alloc (&objfile->misc_obstack, SIZEOF_SECTION_OFFSETS);
 >   	      memcpy (objfile->section_offsets, offsets, SIZEOF_SECTION_OFFSETS);
 >   	      objfile->num_sections = num_offsets;
 >   
 > *************** allocate_psymtab (char *filename, struct
 > *** 1981,1993 ****
 >         objfile->free_psymtabs = psymtab->next;
 >       }
 >     else
 > !     psymtab = (struct partial_symtab *)
 > !       obstack_alloc (&objfile->psymbol_obstack,
 > ! 		     sizeof (struct partial_symtab));
 >   
 >     memset (psymtab, 0, sizeof (struct partial_symtab));
 > !   psymtab->filename = obsavestring (filename, strlen (filename),
 > ! 				    &objfile->psymbol_obstack);
 >     psymtab->symtab = NULL;
 >   
 >     /* Prepend it to the psymtab list for the objfile it belongs to.
 > --- 1984,1993 ----
 >         objfile->free_psymtabs = psymtab->next;
 >       }
 >     else
 > !     psymtab = (struct partial_symtab *) obstack_alloc (&objfile->misc_obstack, sizeof (struct partial_symtab));
 >   
 >     memset (psymtab, 0, sizeof (struct partial_symtab));
 > !   psymtab->filename = obsavestring (filename, strlen(filename), &objfile->misc_obstack);
 >     psymtab->symtab = NULL;
 >   
 >     /* Prepend it to the psymtab list for the objfile it belongs to.
 > Index: objfiles.c
 > ===================================================================
 > RCS file: /cvs/src/src/gdb/objfiles.c,v
 > retrieving revision 1.15
 > diff -c -3 -p -w -B -b -r1.15 objfiles.c
 > *** objfiles.c	2001/03/06 08:21:11	1.15
 > --- objfiles.c	2001/05/29 17:27:57
 > *************** add_to_objfile_sections (bfd *abfd, sec_
 > *** 96,102 ****
 >     section.ovly_mapped = 0;
 >     section.addr = bfd_section_vma (abfd, asect);
 >     section.endaddr = section.addr + bfd_section_size (abfd, asect);
 > !   obstack_grow (&objfile->psymbol_obstack, (char *) &section, sizeof (section));
 >     objfile->sections_end = (struct obj_section *) (((unsigned long) objfile->sections_end) + 1);
 >   }
 >   
 > --- 96,102 ----
 >     section.ovly_mapped = 0;
 >     section.addr = bfd_section_vma (abfd, asect);
 >     section.endaddr = section.addr + bfd_section_size (abfd, asect);
 > !   obstack_grow (&objfile->misc_obstack, (char *) &section, sizeof (section));
 >     objfile->sections_end = (struct obj_section *) (((unsigned long) objfile->sections_end) + 1);
 >   }
 >   
 > *************** build_objfile_section_table (struct objf
 > *** 121,134 ****
 >   {
 >     /* objfile->sections can be already set when reading a mapped symbol
 >        file.  I believe that we do need to rebuild the section table in
 > !      this case (we rebuild other things derived from the bfd), but we
 > !      can't free the old one (it's in the psymbol_obstack).  So we just
 > !      waste some memory.  */
 >   
 >     objfile->sections_end = 0;
 >     bfd_map_over_sections (objfile->obfd, add_to_objfile_sections, (char *) objfile);
 >     objfile->sections = (struct obj_section *)
 > !     obstack_finish (&objfile->psymbol_obstack);
 >     objfile->sections_end = objfile->sections + (unsigned long) objfile->sections_end;
 >     return (0);
 >   }
 > --- 121,137 ----
 >   {
 >     /* objfile->sections can be already set when reading a mapped symbol
 >        file.  I believe that we do need to rebuild the section table in
 > !      this case (we rebuild other things derived from the bfd).
 > !      DJB - 05-27-2001 
 > !      It's in the misc_obstack now, feel free to do what you need to.
 > !      All the stuff in objfile that was on the psymbol obstack, but didnt' belong, is in the misc obstack, which 
 > !      I think is all the stuff you want to blow away anyway.
 > !      */
 >   
 >     objfile->sections_end = 0;
 >     bfd_map_over_sections (objfile->obfd, add_to_objfile_sections, (char *) objfile);
 >     objfile->sections = (struct obj_section *)
 > !     obstack_finish (&objfile->misc_obstack);
 >     objfile->sections_end = objfile->sections + (unsigned long) objfile->sections_end;
 >     return (0);
 >   }
 > *************** allocate_objfile (bfd *abfd, int flags)
 > *** 188,193 ****
 > --- 191,198 ----
 >   	      /* Update pointers to functions to *our* copies */
 >   	      obstack_chunkfun (&objfile->psymbol_cache.cache, xmmalloc);
 >   	      obstack_freefun (&objfile->psymbol_cache.cache, mfree);
 > + 	      obstack_chunkfun (&objfile->misc_obstack, xmmalloc);
 > + 	      obstack_freefun (&objfile->misc_obstack, mfree);
 >   	      obstack_chunkfun (&objfile->psymbol_obstack, xmmalloc);
 >   	      obstack_freefun (&objfile->psymbol_obstack, mfree);
 >   	      obstack_chunkfun (&objfile->symbol_obstack, xmmalloc);
 > *************** allocate_objfile (bfd *abfd, int flags)
 > *** 218,223 ****
 > --- 223,231 ----
 >   	      obstack_specify_allocation_with_arg (&objfile->psymbol_cache.cache,
 >   						   0, 0, xmmalloc, mfree,
 >   						   objfile->md);
 > + 	      obstack_specify_allocation_with_arg (&objfile->misc_obstack,
 > + 						   0, 0, xmmalloc, mfree,
 > + 						   objfile->md);
 >   	      obstack_specify_allocation_with_arg (&objfile->psymbol_obstack,
 >   						   0, 0, xmmalloc, mfree,
 >   						   objfile->md);
 > *************** allocate_objfile (bfd *abfd, int flags)
 > *** 264,269 ****
 > --- 272,279 ----
 >         objfile->md = NULL;
 >         obstack_specify_allocation (&objfile->psymbol_cache.cache, 0, 0,
 >   				  xmalloc, xfree);
 > +       obstack_specify_allocation (&objfile->misc_obstack, 0, 0, xmalloc,
 > + 				  xfree);
 >         obstack_specify_allocation (&objfile->psymbol_obstack, 0, 0, xmalloc,
 >   				  xfree);
 >         obstack_specify_allocation (&objfile->symbol_obstack, 0, 0, xmalloc,
 > *************** free_objfile (struct objfile *objfile)
 > *** 475,480 ****
 > --- 485,491 ----
 >   	mfree (objfile->md, objfile->static_psymbols.list);
 >         /* Free the obstacks for non-reusable objfiles */
 >         free_bcache (&objfile->psymbol_cache);
 > +       obstack_free (&objfile->misc_obstack, 0);
 >         obstack_free (&objfile->psymbol_obstack, 0);
 >         obstack_free (&objfile->symbol_obstack, 0);
 >         obstack_free (&objfile->type_obstack, 0);
 > Index: objfiles.h
 > ===================================================================
 > RCS file: /cvs/src/src/gdb/objfiles.h,v
 > retrieving revision 1.8
 > diff -c -3 -p -w -B -b -r1.8 objfiles.h
 > *** objfiles.h	2001/03/06 08:21:11	1.8
 > --- objfiles.h	2001/05/29 17:28:00
 > *************** struct objfile
 > *** 269,274 ****
 > --- 269,275 ----
 >       /* Obstacks to hold objects that should be freed when we load a new symbol
 >          table from this object file. */
 >   
 > +     struct obstack misc_obstack;	/* Misc stuff */
 >       struct obstack psymbol_obstack;	/* Partial symbols */
 >       struct obstack symbol_obstack;	/* Full symbols */
 >       struct obstack type_obstack;	/* Types */
 > 
 > -- 
 > "I used to be a narrator for bad mimes.
 > "-Steven Wright
 > 

Re: [RFA]: Add misc_obstack to object files.

[Daniel Berlin]

Elena Zannoni <ezannoni@cygnus.com> writes:

> Daniel Berlin writes:
> > 
> > This way, we stop putting things in the psymbol_obstack that don't
> > belong.  
> > 
> 
> Dan, can you elaborate a bit on why we need this?
Because these things don't belong in the psymbol obstack.
They are section offsets, not partial symbols.

> Why are you removing
> the partial symbol table from the psymbol_objstack?
I'm not. At all in fact.
I'm specifically trying to make it so *all* that is in the
psymbol_obstack is the partial symbol table.
we've been stuffing random stuff like section offsets into the
psymbol_obstack, because it was handy.
This is wrong.
If we need a misc place to put info like section offsets, that isn't
large enough to deserve it's own obstack on it's own, then all the
misc stuff together should go in a misc_obstack.

>  Was this intended?
> There are several other things that get allocated on the
> psymbol_objstack, for instance look in xcoffread.c, somread.c,
> etc. Why just remove the section offset stuff?
Because I haven't gotten to the others yet.
And there is no harm in taking time to make sure it gets done right.

> 
> If your intent was to change the allocation of the section offset
> information, from psymbol_obstack to misc_obstack, why not modify also
> the same allocations done in xcoffread.c, elfread.c, somread.c?
Because i haven't gotten there yet.
:)
I did it as I saw them.

In actuality, what i was doing was freeing the psymbol obstack when we
were completely done with partial symbols, and seeing what broke.
They never broke, so i never noticed them.

When i submit a large patch that does all this in one fell swoop,
someone would say to break it down.
So consider this a first step, rather than a done deal.

> 
> Thanks
> Elena
> 
> 
> > 2001-05-27  Daniel Berlin  <dan@cgsoftware.com>
> > 
> > 	* symfile.c (default_symfile_offsets): Allocate in misc_obstack.
> > 	(reread_symbols): Handle misc_obstack too, and use it where
> > 	psymbol_obstack didn't belong. 
> > 	(allocate_psymtab): Ditto.
> > 
> > 	* objfiles.c (add_to_objfile_sections):  Use misc_obstack, not psymbol_obstack.
> > 	(build_objfile_section_table): Ditto.
> > 	(free_objfile): Free the misc_obstack.
> > 	(allocate_objfile): Setup misc_obstack too.
> > 
> > 	* objfiles.h: Add misc_obstack to object file.
> > 
> > Index: symfile.c
> > ===================================================================
> > RCS file: /cvs/src/src/gdb/symfile.c,v
> > retrieving revision 1.32
> > diff -c -3 -p -w -B -b -r1.32 symfile.c
> > *** symfile.c	2001/05/10 15:33:21	1.32
> > --- symfile.c	2001/05/29 17:27:51
> > *************** default_symfile_offsets (struct objfile 
> > *** 500,506 ****
> >   
> >     objfile->num_sections = SECT_OFF_MAX;
> >     objfile->section_offsets = (struct section_offsets *)
> > !     obstack_alloc (&objfile->psymbol_obstack, SIZEOF_SECTION_OFFSETS);
> >     memset (objfile->section_offsets, 0, SIZEOF_SECTION_OFFSETS);
> >   
> >     /* Now calculate offsets for section that were specified by the
> > --- 500,506 ----
> >   
> >     objfile->num_sections = SECT_OFF_MAX;
> >     objfile->section_offsets = (struct section_offsets *)
> > !     obstack_alloc (&objfile->misc_obstack, SIZEOF_SECTION_OFFSETS);
> >     memset (objfile->section_offsets, 0, SIZEOF_SECTION_OFFSETS);
> >   
> >     /* Now calculate offsets for section that were specified by the
> > *************** reread_symbols (void)
> > *** 1679,1684 ****
> > --- 1679,1685 ----
> >   
> >   	      /* Free the obstacks for non-reusable objfiles */
> >   	      free_bcache (&objfile->psymbol_cache);
> > + 	      obstack_free (&objfile->misc_obstack, 0);
> >   	      obstack_free (&objfile->psymbol_obstack, 0);
> >   	      obstack_free (&objfile->symbol_obstack, 0);
> >   	      obstack_free (&objfile->type_obstack, 0);
> > *************** reread_symbols (void)
> > *** 1704,1709 ****
> > --- 1705,1712 ----
> >   	         it is empty.  */
> >   	      obstack_specify_allocation (&objfile->psymbol_cache.cache, 0, 0,
> >   					  xmalloc, xfree);
> > + 	      obstack_specify_allocation (&objfile->misc_obstack, 0, 0,
> > + 					  xmalloc, xfree);
> >   	      obstack_specify_allocation (&objfile->psymbol_obstack, 0, 0,
> >   					  xmalloc, xfree);
> >   	      obstack_specify_allocation (&objfile->symbol_obstack, 0, 0,
> > *************** reread_symbols (void)
> > *** 1719,1725 ****
> >   	      /* We use the same section offsets as from last time.  I'm not
> >   	         sure whether that is always correct for shared libraries.  */
> >   	      objfile->section_offsets = (struct section_offsets *)
> > ! 		obstack_alloc (&objfile->psymbol_obstack, SIZEOF_SECTION_OFFSETS);
> >   	      memcpy (objfile->section_offsets, offsets, SIZEOF_SECTION_OFFSETS);
> >   	      objfile->num_sections = num_offsets;
> >   
> > --- 1722,1728 ----
> >   	      /* We use the same section offsets as from last time.  I'm not
> >   	         sure whether that is always correct for shared libraries.  */
> >   	      objfile->section_offsets = (struct section_offsets *)
> > ! 		obstack_alloc (&objfile->misc_obstack, SIZEOF_SECTION_OFFSETS);
> >   	      memcpy (objfile->section_offsets, offsets, SIZEOF_SECTION_OFFSETS);
> >   	      objfile->num_sections = num_offsets;
> >   
> > *************** allocate_psymtab (char *filename, struct
> > *** 1981,1993 ****
> >         objfile->free_psymtabs = psymtab->next;
> >       }
> >     else
> > !     psymtab = (struct partial_symtab *)
> > !       obstack_alloc (&objfile->psymbol_obstack,
> > ! 		     sizeof (struct partial_symtab));
> >   
> >     memset (psymtab, 0, sizeof (struct partial_symtab));
> > !   psymtab->filename = obsavestring (filename, strlen (filename),
> > ! 				    &objfile->psymbol_obstack);
> >     psymtab->symtab = NULL;
> >   
> >     /* Prepend it to the psymtab list for the objfile it belongs to.
> > --- 1984,1993 ----
> >         objfile->free_psymtabs = psymtab->next;
> >       }
> >     else
> > !     psymtab = (struct partial_symtab *) obstack_alloc (&objfile->misc_obstack, sizeof (struct partial_symtab));
> >   
> >     memset (psymtab, 0, sizeof (struct partial_symtab));
> > !   psymtab->filename = obsavestring (filename, strlen(filename), &objfile->misc_obstack);
> >     psymtab->symtab = NULL;
> >   
> >     /* Prepend it to the psymtab list for the objfile it belongs to.
> > Index: objfiles.c
> > ===================================================================
> > RCS file: /cvs/src/src/gdb/objfiles.c,v
> > retrieving revision 1.15
> > diff -c -3 -p -w -B -b -r1.15 objfiles.c
> > *** objfiles.c	2001/03/06 08:21:11	1.15
> > --- objfiles.c	2001/05/29 17:27:57
> > *************** add_to_objfile_sections (bfd *abfd, sec_
> > *** 96,102 ****
> >     section.ovly_mapped = 0;
> >     section.addr = bfd_section_vma (abfd, asect);
> >     section.endaddr = section.addr + bfd_section_size (abfd, asect);
> > !   obstack_grow (&objfile->psymbol_obstack, (char *) &section, sizeof (section));
> >     objfile->sections_end = (struct obj_section *) (((unsigned long) objfile->sections_end) + 1);
> >   }
> >   
> > --- 96,102 ----
> >     section.ovly_mapped = 0;
> >     section.addr = bfd_section_vma (abfd, asect);
> >     section.endaddr = section.addr + bfd_section_size (abfd, asect);
> > !   obstack_grow (&objfile->misc_obstack, (char *) &section, sizeof (section));
> >     objfile->sections_end = (struct obj_section *) (((unsigned long) objfile->sections_end) + 1);
> >   }
> >   
> > *************** build_objfile_section_table (struct objf
> > *** 121,134 ****
> >   {
> >     /* objfile->sections can be already set when reading a mapped symbol
> >        file.  I believe that we do need to rebuild the section table in
> > !      this case (we rebuild other things derived from the bfd), but we
> > !      can't free the old one (it's in the psymbol_obstack).  So we just
> > !      waste some memory.  */
> >   
> >     objfile->sections_end = 0;
> >     bfd_map_over_sections (objfile->obfd, add_to_objfile_sections, (char *) objfile);
> >     objfile->sections = (struct obj_section *)
> > !     obstack_finish (&objfile->psymbol_obstack);
> >     objfile->sections_end = objfile->sections + (unsigned long) objfile->sections_end;
> >     return (0);
> >   }
> > --- 121,137 ----
> >   {
> >     /* objfile->sections can be already set when reading a mapped symbol
> >        file.  I believe that we do need to rebuild the section table in
> > !      this case (we rebuild other things derived from the bfd).
> > !      DJB - 05-27-2001 
> > !      It's in the misc_obstack now, feel free to do what you need to.
> > !      All the stuff in objfile that was on the psymbol obstack, but didnt' belong, is in the misc obstack, which 
> > !      I think is all the stuff you want to blow away anyway.
> > !      */
> >   
> >     objfile->sections_end = 0;
> >     bfd_map_over_sections (objfile->obfd, add_to_objfile_sections, (char *) objfile);
> >     objfile->sections = (struct obj_section *)
> > !     obstack_finish (&objfile->misc_obstack);
> >     objfile->sections_end = objfile->sections + (unsigned long) objfile->sections_end;
> >     return (0);
> >   }
> > *************** allocate_objfile (bfd *abfd, int flags)
> > *** 188,193 ****
> > --- 191,198 ----
> >   	      /* Update pointers to functions to *our* copies */
> >   	      obstack_chunkfun (&objfile->psymbol_cache.cache, xmmalloc);
> >   	      obstack_freefun (&objfile->psymbol_cache.cache, mfree);
> > + 	      obstack_chunkfun (&objfile->misc_obstack, xmmalloc);
> > + 	      obstack_freefun (&objfile->misc_obstack, mfree);
> >   	      obstack_chunkfun (&objfile->psymbol_obstack, xmmalloc);
> >   	      obstack_freefun (&objfile->psymbol_obstack, mfree);
> >   	      obstack_chunkfun (&objfile->symbol_obstack, xmmalloc);
> > *************** allocate_objfile (bfd *abfd, int flags)
> > *** 218,223 ****
> > --- 223,231 ----
> >   	      obstack_specify_allocation_with_arg (&objfile->psymbol_cache.cache,
> >   						   0, 0, xmmalloc, mfree,
> >   						   objfile->md);
> > + 	      obstack_specify_allocation_with_arg (&objfile->misc_obstack,
> > + 						   0, 0, xmmalloc, mfree,
> > + 						   objfile->md);
> >   	      obstack_specify_allocation_with_arg (&objfile->psymbol_obstack,
> >   						   0, 0, xmmalloc, mfree,
> >   						   objfile->md);
> > *************** allocate_objfile (bfd *abfd, int flags)
> > *** 264,269 ****
> > --- 272,279 ----
> >         objfile->md = NULL;
> >         obstack_specify_allocation (&objfile->psymbol_cache.cache, 0, 0,
> >   				  xmalloc, xfree);
> > +       obstack_specify_allocation (&objfile->misc_obstack, 0, 0, xmalloc,
> > + 				  xfree);
> >         obstack_specify_allocation (&objfile->psymbol_obstack, 0, 0, xmalloc,
> >   				  xfree);
> >         obstack_specify_allocation (&objfile->symbol_obstack, 0, 0, xmalloc,
> > *************** free_objfile (struct objfile *objfile)
> > *** 475,480 ****
> > --- 485,491 ----
> >   	mfree (objfile->md, objfile->static_psymbols.list);
> >         /* Free the obstacks for non-reusable objfiles */
> >         free_bcache (&objfile->psymbol_cache);
> > +       obstack_free (&objfile->misc_obstack, 0);
> >         obstack_free (&objfile->psymbol_obstack, 0);
> >         obstack_free (&objfile->symbol_obstack, 0);
> >         obstack_free (&objfile->type_obstack, 0);
> > Index: objfiles.h
> > ===================================================================
> > RCS file: /cvs/src/src/gdb/objfiles.h,v
> > retrieving revision 1.8
> > diff -c -3 -p -w -B -b -r1.8 objfiles.h
> > *** objfiles.h	2001/03/06 08:21:11	1.8
> > --- objfiles.h	2001/05/29 17:28:00
> > *************** struct objfile
> > *** 269,274 ****
> > --- 269,275 ----
> >       /* Obstacks to hold objects that should be freed when we load a new symbol
> >          table from this object file. */
> >   
> > +     struct obstack misc_obstack;	/* Misc stuff */
> >       struct obstack psymbol_obstack;	/* Partial symbols */
> >       struct obstack symbol_obstack;	/* Full symbols */
> >       struct obstack type_obstack;	/* Types */
> > 
> > -- 
> > "I used to be a narrator for bad mimes.
> > "-Steven Wright
> > 

-- 
"I went into a clothes store the other day and a salesman walked
up to me and said, "Can I help you?"  and I said "Yeah, do you
got anything I like?"  He said, "What do you mean do we have
anything you like?"  I said, "You started this."
"-Steven Wright

Re: [RFA]: Add misc_obstack to object files.

[Elena Zannoni]

Daniel Berlin writes:
 > Elena Zannoni <ezannoni@cygnus.com> writes:
 > 
 > > Daniel Berlin writes:
 > > > 
 > > > This way, we stop putting things in the psymbol_obstack that don't
 > > > belong.  
 > > > 
 > > 
 > > Dan, can you elaborate a bit on why we need this?
 > Because these things don't belong in the psymbol obstack.
 > They are section offsets, not partial symbols.
 > 

Dan, I am really sorry, but still I cannot see a real reason for this
change emerging from your mail. 
You are doing this in response to some bug you saw, I assume, but what that
bug is has not been explained.

Quoting src/gdb/CONTRIBUTE:

o       Submitting Patches

        Every patch must have several pieces of information before we
        can properly evaluate it.

        A description of the bug and how your patch fixes this
        bug. A reference to a testsuite failure is very helpful. For
        new features a description of the feature and your
        implementation.

[....]
 
Supplemental information for GDB:

o       Please try to run the relevant testsuite before and after
        committing a patch

        If the contributor doesn't do it then the maintainer will.  A
        contributor might include before/after test results in their
        contribution.


o       For bug fixes, please try to include a way of
        demonstrating that the patch actually fixes something.

        The best way of doing this is to ensure that the
        testsuite contains one or more test cases that
        fail without the fix but pass with the fix.

        People are encouraged to submit patches that extend
        the testsuite.


o       Please read your patch before submitting it.

        A patch containing several unrelated changes or
        arbitrary reformats will be returned with a request
        to re-formatting / split it.


 > > Why are you removing
 > > the partial symbol table from the psymbol_objstack?
 > I'm not. At all in fact.
 > I'm specifically trying to make it so *all* that is in the
 > psymbol_obstack is the partial symbol table.
 > we've been stuffing random stuff like section offsets into the
 > psymbol_obstack, because it was handy.
 > This is wrong.
 > If we need a misc place to put info like section offsets, that isn't
 > large enough to deserve it's own obstack on it's own, then all the
 > misc stuff together should go in a misc_obstack.

Then your patch includes a diff that is unrelated.

 > 
 > >  Was this intended?
 > > There are several other things that get allocated on the
 > > psymbol_objstack, for instance look in xcoffread.c, somread.c,
 > > etc. Why just remove the section offset stuff?
 > Because I haven't gotten to the others yet.
 > And there is no harm in taking time to make sure it gets done right.
 > 

If you have a roadmap in mind, you should explain it when you submit
the patch.

 > > 
 > > If your intent was to change the allocation of the section offset
 > > information, from psymbol_obstack to misc_obstack, why not modify also
 > > the same allocations done in xcoffread.c, elfread.c, somread.c?
 > Because i haven't gotten there yet.
 > :)
 > I did it as I saw them.
 > 
 > In actuality, what i was doing was freeing the psymbol obstack when we
 > were completely done with partial symbols, and seeing what broke.
 > They never broke, so i never noticed them.
 > 
 > When i submit a large patch that does all this in one fell swoop,
 > someone would say to break it down.
 > So consider this a first step, rather than a done deal.
 > 

I am encouraging you to resubmit the patch accompanied by coherent
explanation and rationale.

Elena


 > > 
 > > Thanks
 > > Elena
 > > 
 > > 
 > > > 2001-05-27  Daniel Berlin  <dan@cgsoftware.com>
 > > > 
 > > > 	* symfile.c (default_symfile_offsets): Allocate in misc_obstack.
 > > > 	(reread_symbols): Handle misc_obstack too, and use it where
 > > > 	psymbol_obstack didn't belong. 
 > > > 	(allocate_psymtab): Ditto.
 > > > 
 > > > 	* objfiles.c (add_to_objfile_sections):  Use misc_obstack, not psymbol_obstack.
 > > > 	(build_objfile_section_table): Ditto.
 > > > 	(free_objfile): Free the misc_obstack.
 > > > 	(allocate_objfile): Setup misc_obstack too.
 > > > 
 > > > 	* objfiles.h: Add misc_obstack to object file.
 > > > 
 > > > Index: symfile.c
 > > > ===================================================================
 > > > RCS file: /cvs/src/src/gdb/symfile.c,v
 > > > retrieving revision 1.32
 > > > diff -c -3 -p -w -B -b -r1.32 symfile.c
 > > > *** symfile.c	2001/05/10 15:33:21	1.32
 > > > --- symfile.c	2001/05/29 17:27:51
 > > > *************** default_symfile_offsets (struct objfile 
 > > > *** 500,506 ****
 > > >   
 > > >     objfile->num_sections = SECT_OFF_MAX;
 > > >     objfile->section_offsets = (struct section_offsets *)
 > > > !     obstack_alloc (&objfile->psymbol_obstack, SIZEOF_SECTION_OFFSETS);
 > > >     memset (objfile->section_offsets, 0, SIZEOF_SECTION_OFFSETS);
 > > >   
 > > >     /* Now calculate offsets for section that were specified by the
 > > > --- 500,506 ----
 > > >   
 > > >     objfile->num_sections = SECT_OFF_MAX;
 > > >     objfile->section_offsets = (struct section_offsets *)
 > > > !     obstack_alloc (&objfile->misc_obstack, SIZEOF_SECTION_OFFSETS);
 > > >     memset (objfile->section_offsets, 0, SIZEOF_SECTION_OFFSETS);
 > > >   
 > > >     /* Now calculate offsets for section that were specified by the
 > > > *************** reread_symbols (void)
 > > > *** 1679,1684 ****
 > > > --- 1679,1685 ----
 > > >   
 > > >   	      /* Free the obstacks for non-reusable objfiles */
 > > >   	      free_bcache (&objfile->psymbol_cache);
 > > > + 	      obstack_free (&objfile->misc_obstack, 0);
 > > >   	      obstack_free (&objfile->psymbol_obstack, 0);
 > > >   	      obstack_free (&objfile->symbol_obstack, 0);
 > > >   	      obstack_free (&objfile->type_obstack, 0);
 > > > *************** reread_symbols (void)
 > > > *** 1704,1709 ****
 > > > --- 1705,1712 ----
 > > >   	         it is empty.  */
 > > >   	      obstack_specify_allocation (&objfile->psymbol_cache.cache, 0, 0,
 > > >   					  xmalloc, xfree);
 > > > + 	      obstack_specify_allocation (&objfile->misc_obstack, 0, 0,
 > > > + 					  xmalloc, xfree);
 > > >   	      obstack_specify_allocation (&objfile->psymbol_obstack, 0, 0,
 > > >   					  xmalloc, xfree);
 > > >   	      obstack_specify_allocation (&objfile->symbol_obstack, 0, 0,
 > > > *************** reread_symbols (void)
 > > > *** 1719,1725 ****
 > > >   	      /* We use the same section offsets as from last time.  I'm not
 > > >   	         sure whether that is always correct for shared libraries.  */
 > > >   	      objfile->section_offsets = (struct section_offsets *)
 > > > ! 		obstack_alloc (&objfile->psymbol_obstack, SIZEOF_SECTION_OFFSETS);
 > > >   	      memcpy (objfile->section_offsets, offsets, SIZEOF_SECTION_OFFSETS);
 > > >   	      objfile->num_sections = num_offsets;
 > > >   
 > > > --- 1722,1728 ----
 > > >   	      /* We use the same section offsets as from last time.  I'm not
 > > >   	         sure whether that is always correct for shared libraries.  */
 > > >   	      objfile->section_offsets = (struct section_offsets *)
 > > > ! 		obstack_alloc (&objfile->misc_obstack, SIZEOF_SECTION_OFFSETS);
 > > >   	      memcpy (objfile->section_offsets, offsets, SIZEOF_SECTION_OFFSETS);
 > > >   	      objfile->num_sections = num_offsets;
 > > >   
 > > > *************** allocate_psymtab (char *filename, struct
 > > > *** 1981,1993 ****
 > > >         objfile->free_psymtabs = psymtab->next;
 > > >       }
 > > >     else
 > > > !     psymtab = (struct partial_symtab *)
 > > > !       obstack_alloc (&objfile->psymbol_obstack,
 > > > ! 		     sizeof (struct partial_symtab));
 > > >   
 > > >     memset (psymtab, 0, sizeof (struct partial_symtab));
 > > > !   psymtab->filename = obsavestring (filename, strlen (filename),
 > > > ! 				    &objfile->psymbol_obstack);
 > > >     psymtab->symtab = NULL;
 > > >   
 > > >     /* Prepend it to the psymtab list for the objfile it belongs to.
 > > > --- 1984,1993 ----
 > > >         objfile->free_psymtabs = psymtab->next;
 > > >       }
 > > >     else
 > > > !     psymtab = (struct partial_symtab *) obstack_alloc (&objfile->misc_obstack, sizeof (struct partial_symtab));
 > > >   
 > > >     memset (psymtab, 0, sizeof (struct partial_symtab));
 > > > !   psymtab->filename = obsavestring (filename, strlen(filename), &objfile->misc_obstack);
 > > >     psymtab->symtab = NULL;
 > > >   
 > > >     /* Prepend it to the psymtab list for the objfile it belongs to.
 > > > Index: objfiles.c
 > > > ===================================================================
 > > > RCS file: /cvs/src/src/gdb/objfiles.c,v
 > > > retrieving revision 1.15
 > > > diff -c -3 -p -w -B -b -r1.15 objfiles.c
 > > > *** objfiles.c	2001/03/06 08:21:11	1.15
 > > > --- objfiles.c	2001/05/29 17:27:57
 > > > *************** add_to_objfile_sections (bfd *abfd, sec_
 > > > *** 96,102 ****
 > > >     section.ovly_mapped = 0;
 > > >     section.addr = bfd_section_vma (abfd, asect);
 > > >     section.endaddr = section.addr + bfd_section_size (abfd, asect);
 > > > !   obstack_grow (&objfile->psymbol_obstack, (char *) &section, sizeof (section));
 > > >     objfile->sections_end = (struct obj_section *) (((unsigned long) objfile->sections_end) + 1);
 > > >   }
 > > >   
 > > > --- 96,102 ----
 > > >     section.ovly_mapped = 0;
 > > >     section.addr = bfd_section_vma (abfd, asect);
 > > >     section.endaddr = section.addr + bfd_section_size (abfd, asect);
 > > > !   obstack_grow (&objfile->misc_obstack, (char *) &section, sizeof (section));
 > > >     objfile->sections_end = (struct obj_section *) (((unsigned long) objfile->sections_end) + 1);
 > > >   }
 > > >   
 > > > *************** build_objfile_section_table (struct objf
 > > > *** 121,134 ****
 > > >   {
 > > >     /* objfile->sections can be already set when reading a mapped symbol
 > > >        file.  I believe that we do need to rebuild the section table in
 > > > !      this case (we rebuild other things derived from the bfd), but we
 > > > !      can't free the old one (it's in the psymbol_obstack).  So we just
 > > > !      waste some memory.  */
 > > >   
 > > >     objfile->sections_end = 0;
 > > >     bfd_map_over_sections (objfile->obfd, add_to_objfile_sections, (char *) objfile);
 > > >     objfile->sections = (struct obj_section *)
 > > > !     obstack_finish (&objfile->psymbol_obstack);
 > > >     objfile->sections_end = objfile->sections + (unsigned long) objfile->sections_end;
 > > >     return (0);
 > > >   }
 > > > --- 121,137 ----
 > > >   {
 > > >     /* objfile->sections can be already set when reading a mapped symbol
 > > >        file.  I believe that we do need to rebuild the section table in
 > > > !      this case (we rebuild other things derived from the bfd).
 > > > !      DJB - 05-27-2001 
 > > > !      It's in the misc_obstack now, feel free to do what you need to.
 > > > !      All the stuff in objfile that was on the psymbol obstack, but didnt' belong, is in the misc obstack, which 
 > > > !      I think is all the stuff you want to blow away anyway.
 > > > !      */
 > > >   
 > > >     objfile->sections_end = 0;
 > > >     bfd_map_over_sections (objfile->obfd, add_to_objfile_sections, (char *) objfile);
 > > >     objfile->sections = (struct obj_section *)
 > > > !     obstack_finish (&objfile->misc_obstack);
 > > >     objfile->sections_end = objfile->sections + (unsigned long) objfile->sections_end;
 > > >     return (0);
 > > >   }
 > > > *************** allocate_objfile (bfd *abfd, int flags)
 > > > *** 188,193 ****
 > > > --- 191,198 ----
 > > >   	      /* Update pointers to functions to *our* copies */
 > > >   	      obstack_chunkfun (&objfile->psymbol_cache.cache, xmmalloc);
 > > >   	      obstack_freefun (&objfile->psymbol_cache.cache, mfree);
 > > > + 	      obstack_chunkfun (&objfile->misc_obstack, xmmalloc);
 > > > + 	      obstack_freefun (&objfile->misc_obstack, mfree);
 > > >   	      obstack_chunkfun (&objfile->psymbol_obstack, xmmalloc);
 > > >   	      obstack_freefun (&objfile->psymbol_obstack, mfree);
 > > >   	      obstack_chunkfun (&objfile->symbol_obstack, xmmalloc);
 > > > *************** allocate_objfile (bfd *abfd, int flags)
 > > > *** 218,223 ****
 > > > --- 223,231 ----
 > > >   	      obstack_specify_allocation_with_arg (&objfile->psymbol_cache.cache,
 > > >   						   0, 0, xmmalloc, mfree,
 > > >   						   objfile->md);
 > > > + 	      obstack_specify_allocation_with_arg (&objfile->misc_obstack,
 > > > + 						   0, 0, xmmalloc, mfree,
 > > > + 						   objfile->md);
 > > >   	      obstack_specify_allocation_with_arg (&objfile->psymbol_obstack,
 > > >   						   0, 0, xmmalloc, mfree,
 > > >   						   objfile->md);
 > > > *************** allocate_objfile (bfd *abfd, int flags)
 > > > *** 264,269 ****
 > > > --- 272,279 ----
 > > >         objfile->md = NULL;
 > > >         obstack_specify_allocation (&objfile->psymbol_cache.cache, 0, 0,
 > > >   				  xmalloc, xfree);
 > > > +       obstack_specify_allocation (&objfile->misc_obstack, 0, 0, xmalloc,
 > > > + 				  xfree);
 > > >         obstack_specify_allocation (&objfile->psymbol_obstack, 0, 0, xmalloc,
 > > >   				  xfree);
 > > >         obstack_specify_allocation (&objfile->symbol_obstack, 0, 0, xmalloc,
 > > > *************** free_objfile (struct objfile *objfile)
 > > > *** 475,480 ****
 > > > --- 485,491 ----
 > > >   	mfree (objfile->md, objfile->static_psymbols.list);
 > > >         /* Free the obstacks for non-reusable objfiles */
 > > >         free_bcache (&objfile->psymbol_cache);
 > > > +       obstack_free (&objfile->misc_obstack, 0);
 > > >         obstack_free (&objfile->psymbol_obstack, 0);
 > > >         obstack_free (&objfile->symbol_obstack, 0);
 > > >         obstack_free (&objfile->type_obstack, 0);
 > > > Index: objfiles.h
 > > > ===================================================================
 > > > RCS file: /cvs/src/src/gdb/objfiles.h,v
 > > > retrieving revision 1.8
 > > > diff -c -3 -p -w -B -b -r1.8 objfiles.h
 > > > *** objfiles.h	2001/03/06 08:21:11	1.8
 > > > --- objfiles.h	2001/05/29 17:28:00
 > > > *************** struct objfile
 > > > *** 269,274 ****
 > > > --- 269,275 ----
 > > >       /* Obstacks to hold objects that should be freed when we load a new symbol
 > > >          table from this object file. */
 > > >   
 > > > +     struct obstack misc_obstack;	/* Misc stuff */
 > > >       struct obstack psymbol_obstack;	/* Partial symbols */
 > > >       struct obstack symbol_obstack;	/* Full symbols */
 > > >       struct obstack type_obstack;	/* Types */
 > > > 
 > > > -- 
 > > > "I used to be a narrator for bad mimes.
 > > > "-Steven Wright
 > > > 
 > 
 > -- 
 > "I went into a clothes store the other day and a salesman walked
 > up to me and said, "Can I help you?"  and I said "Yeah, do you
 > got anything I like?"  He said, "What do you mean do we have
 > anything you like?"  I said, "You started this."
 > "-Steven Wright
 > 

Re: [RFA]: Add misc_obstack to object files.

[Daniel Berlin]

Elena Zannoni <ezannoni@cygnus.com> writes:

> Daniel Berlin writes:
> > Elena Zannoni <ezannoni@cygnus.com> writes:
> > 
> > > Daniel Berlin writes:
> > > > 
> > > > This way, we stop putting things in the psymbol_obstack that don't
> > > > belong.  
> > > > 
> > > 
> > > Dan, can you elaborate a bit on why we need this?
> > Because these things don't belong in the psymbol obstack.
> > They are section offsets, not partial symbols.
> > 
> 
> Dan, I am really sorry, but still I cannot see a real reason for this
> change emerging from your mail. 

Um.
Okay.
According to objfiles.h:

    struct obstack psymbol_obstack;     /* Partial symbols */
    struct obstack symbol_obstack;      /* Full symbols */
    struct obstack type_obstack;        /* Types */


Notice it doesn't say that section offsets, or other random junk,
should be on the psymbol_obstack.
It says "Partial symbols".
Now, if you want to remove the partial symbols, for that object file,
theoretically, you just remove the psymbol_obstack.  However, because
we allocate other random things, like section offset tables, etc,
which have zip to do with partial symbols, on that obstack, we won't
remove just the partial symbols by removing that obstack.  We'll blow
away the section offset table, the psymtab structures, etc.
This should not be occurring.
It makes as much sense as allocating object file section offsets on the
type_obstack, which is for types only. That is to say, none.

It's the equivalent of having a trash bin marked "white paper only",
and having people knowing throw all kinds of colored paper in there,
for lack of a better place to throw colored paper.
They don't belong.
Not only that, but if you later wanted to remove the white paper, you'd have to sort out
the colored paper, and do something with it, first.

I'm just adding a bin for colored paper, so people will put that stuff
in there instead in the first place, and it will be plainly clear that they are supposed
to be doing so.


> You are doing this in response to some bug you saw, I assume, but what that
> bug is has not been explained.
No, i'm doing it because partial symbols belong on the psymbol
obstack, but section offsets, and other random things don't.
In practice, we've not followed this, because nobody bothered to
create somewhere *else* to put them. I'm attempting to bring us
to doing what we should have been doing in the first place, by
creating this place to put them.

Had I been trying to fix a bug, i would explain what the bug was, and
where it showed up.

This is not a bug, in that nothing is specifically *broken*. It's
perfectly okay to allocate these structures on that obstack, given
that gdb never frees the obstack, it's just not in line with what the
comments say, and the purpose of the psymbol obstack.

> 
> 
> > > Why are you removing
> > > the partial symbol table from the psymbol_objstack?
> > I'm not. At all in fact.
> > I'm specifically trying to make it so *all* that is in the
> > psymbol_obstack is the partial symbol table.
> > we've been stuffing random stuff like section offsets into the
> > psymbol_obstack, because it was handy.
> > This is wrong.
> > If we need a misc place to put info like section offsets, that isn't
> > large enough to deserve it's own obstack on it's own, then all the
> > misc stuff together should go in a misc_obstack.
> 
> Then your patch includes a diff that is unrelated.
Um, how so?
Please point out the portion of the diff unrelated.
The only thing even related to psymtabs there is the fact that they
psymtab structure itself is allocated on the misc obstack, since it
isn't a partial symbol either. It's a partial symbol table structure,
containing pointers to partial symbols. 
The actual partial symbols that fill that table are still allocated on
the psymbol_obstack.
As they should be.
> 
> > 
> > >  Was this intended?
> > > There are several other things that get allocated on the
> > > psymbol_objstack, for instance look in xcoffread.c, somread.c,
> > > etc. Why just remove the section offset stuff?
> > Because I haven't gotten to the others yet.
> > And there is no harm in taking time to make sure it gets done right.
> > 
> 
> If you have a roadmap in mind, you should explain it when you submit
> the patch.

I have no roadmap for when i'd be getting to that.
Eventually.
I could do them all now if it helps, but it'll make the patch bigger.


> 
> > > 
> > > If your intent was to change the allocation of the section offset
> > > information, from psymbol_obstack to misc_obstack, why not modify also
> > > the same allocations done in xcoffread.c, elfread.c, somread.c?
> > Because i haven't gotten there yet.
> > :)
> > I did it as I saw them.
> > 
> > In actuality, what i was doing was freeing the psymbol obstack when we
> > were completely done with partial symbols, and seeing what broke.
> > They never broke, so i never noticed them.
> > 
> > When i submit a large patch that does all this in one fell swoop,
> > someone would say to break it down.
> > So consider this a first step, rather than a done deal.
> > 
> 
> I am encouraging you to resubmit the patch accompanied by coherent
> explanation and rationale.
I believe you are misunderstanding the purpose of the patch, and what
it does, or some portion of it.
Please let me know if the above doesn't clear it up.


> 
> Elena
> 
> 
> > > 
> > > Thanks
> > > Elena
> > > 
> > > 
> > > > 2001-05-27  Daniel Berlin  <dan@cgsoftware.com>
> > > > 
> > > > 	* symfile.c (default_symfile_offsets): Allocate in misc_obstack.
> > > > 	(reread_symbols): Handle misc_obstack too, and use it where
> > > > 	psymbol_obstack didn't belong. 
> > > > 	(allocate_psymtab): Ditto.
> > > > 
> > > > 	* objfiles.c (add_to_objfile_sections):  Use misc_obstack, not psymbol_obstack.
> > > > 	(build_objfile_section_table): Ditto.
> > > > 	(free_objfile): Free the misc_obstack.
> > > > 	(allocate_objfile): Setup misc_obstack too.
> > > > 
> > > > 	* objfiles.h: Add misc_obstack to object file.
> > > > 
> > > > Index: symfile.c
> > > > ===================================================================
> > > > RCS file: /cvs/src/src/gdb/symfile.c,v
> > > > retrieving revision 1.32
> > > > diff -c -3 -p -w -B -b -r1.32 symfile.c
> > > > *** symfile.c	2001/05/10 15:33:21	1.32
> > > > --- symfile.c	2001/05/29 17:27:51
> > > > *************** default_symfile_offsets (struct objfile 
> > > > *** 500,506 ****
> > > >   
> > > >     objfile->num_sections = SECT_OFF_MAX;
> > > >     objfile->section_offsets = (struct section_offsets *)
> > > > !     obstack_alloc (&objfile->psymbol_obstack, SIZEOF_SECTION_OFFSETS);
> > > >     memset (objfile->section_offsets, 0, SIZEOF_SECTION_OFFSETS);
> > > >   
> > > >     /* Now calculate offsets for section that were specified by the
> > > > --- 500,506 ----
> > > >   
> > > >     objfile->num_sections = SECT_OFF_MAX;
> > > >     objfile->section_offsets = (struct section_offsets *)
> > > > !     obstack_alloc (&objfile->misc_obstack, SIZEOF_SECTION_OFFSETS);
> > > >     memset (objfile->section_offsets, 0, SIZEOF_SECTION_OFFSETS);
> > > >   
> > > >     /* Now calculate offsets for section that were specified by the
> > > > *************** reread_symbols (void)
> > > > *** 1679,1684 ****
> > > > --- 1679,1685 ----
> > > >   
> > > >   	      /* Free the obstacks for non-reusable objfiles */
> > > >   	      free_bcache (&objfile->psymbol_cache);
> > > > + 	      obstack_free (&objfile->misc_obstack, 0);
> > > >   	      obstack_free (&objfile->psymbol_obstack, 0);
> > > >   	      obstack_free (&objfile->symbol_obstack, 0);
> > > >   	      obstack_free (&objfile->type_obstack, 0);
> > > > *************** reread_symbols (void)
> > > > *** 1704,1709 ****
> > > > --- 1705,1712 ----
> > > >   	         it is empty.  */
> > > >   	      obstack_specify_allocation (&objfile->psymbol_cache.cache, 0, 0,
> > > >   					  xmalloc, xfree);
> > > > + 	      obstack_specify_allocation (&objfile->misc_obstack, 0, 0,
> > > > + 					  xmalloc, xfree);
> > > >   	      obstack_specify_allocation (&objfile->psymbol_obstack, 0, 0,
> > > >   					  xmalloc, xfree);
> > > >   	      obstack_specify_allocation (&objfile->symbol_obstack, 0, 0,
> > > > *************** reread_symbols (void)
> > > > *** 1719,1725 ****
> > > >   	      /* We use the same section offsets as from last time.  I'm not
> > > >   	         sure whether that is always correct for shared libraries.  */
> > > >   	      objfile->section_offsets = (struct section_offsets *)
> > > > ! 		obstack_alloc (&objfile->psymbol_obstack, SIZEOF_SECTION_OFFSETS);
> > > >   	      memcpy (objfile->section_offsets, offsets, SIZEOF_SECTION_OFFSETS);
> > > >   	      objfile->num_sections = num_offsets;
> > > >   
> > > > --- 1722,1728 ----
> > > >   	      /* We use the same section offsets as from last time.  I'm not
> > > >   	         sure whether that is always correct for shared libraries.  */
> > > >   	      objfile->section_offsets = (struct section_offsets *)
> > > > ! 		obstack_alloc (&objfile->misc_obstack, SIZEOF_SECTION_OFFSETS);
> > > >   	      memcpy (objfile->section_offsets, offsets, SIZEOF_SECTION_OFFSETS);
> > > >   	      objfile->num_sections = num_offsets;
> > > >   
> > > > *************** allocate_psymtab (char *filename, struct
> > > > *** 1981,1993 ****
> > > >         objfile->free_psymtabs = psymtab->next;
> > > >       }
> > > >     else
> > > > !     psymtab = (struct partial_symtab *)
> > > > !       obstack_alloc (&objfile->psymbol_obstack,
> > > > ! 		     sizeof (struct partial_symtab));
> > > >   
> > > >     memset (psymtab, 0, sizeof (struct partial_symtab));
> > > > !   psymtab->filename = obsavestring (filename, strlen (filename),
> > > > ! 				    &objfile->psymbol_obstack);
> > > >     psymtab->symtab = NULL;
> > > >   
> > > >     /* Prepend it to the psymtab list for the objfile it belongs to.
> > > > --- 1984,1993 ----
> > > >         objfile->free_psymtabs = psymtab->next;
> > > >       }
> > > >     else
> > > > !     psymtab = (struct partial_symtab *) obstack_alloc (&objfile->misc_obstack, sizeof (struct partial_symtab));
> > > >   
> > > >     memset (psymtab, 0, sizeof (struct partial_symtab));
> > > > !   psymtab->filename = obsavestring (filename, strlen(filename), &objfile->misc_obstack);
> > > >     psymtab->symtab = NULL;
> > > >   
> > > >     /* Prepend it to the psymtab list for the objfile it belongs to.
> > > > Index: objfiles.c
> > > > ===================================================================
> > > > RCS file: /cvs/src/src/gdb/objfiles.c,v
> > > > retrieving revision 1.15
> > > > diff -c -3 -p -w -B -b -r1.15 objfiles.c
> > > > *** objfiles.c	2001/03/06 08:21:11	1.15
> > > > --- objfiles.c	2001/05/29 17:27:57
> > > > *************** add_to_objfile_sections (bfd *abfd, sec_
> > > > *** 96,102 ****
> > > >     section.ovly_mapped = 0;
> > > >     section.addr = bfd_section_vma (abfd, asect);
> > > >     section.endaddr = section.addr + bfd_section_size (abfd, asect);
> > > > !   obstack_grow (&objfile->psymbol_obstack, (char *) &section, sizeof (section));
> > > >     objfile->sections_end = (struct obj_section *) (((unsigned long) objfile->sections_end) + 1);
> > > >   }
> > > >   
> > > > --- 96,102 ----
> > > >     section.ovly_mapped = 0;
> > > >     section.addr = bfd_section_vma (abfd, asect);
> > > >     section.endaddr = section.addr + bfd_section_size (abfd, asect);
> > > > !   obstack_grow (&objfile->misc_obstack, (char *) &section, sizeof (section));
> > > >     objfile->sections_end = (struct obj_section *) (((unsigned long) objfile->sections_end) + 1);
> > > >   }
> > > >   
> > > > *************** build_objfile_section_table (struct objf
> > > > *** 121,134 ****
> > > >   {
> > > >     /* objfile->sections can be already set when reading a mapped symbol
> > > >        file.  I believe that we do need to rebuild the section table in
> > > > !      this case (we rebuild other things derived from the bfd), but we
> > > > !      can't free the old one (it's in the psymbol_obstack).  So we just
> > > > !      waste some memory.  */
> > > >   
> > > >     objfile->sections_end = 0;
> > > >     bfd_map_over_sections (objfile->obfd, add_to_objfile_sections, (char *) objfile);
> > > >     objfile->sections = (struct obj_section *)
> > > > !     obstack_finish (&objfile->psymbol_obstack);
> > > >     objfile->sections_end = objfile->sections + (unsigned long) objfile->sections_end;
> > > >     return (0);
> > > >   }
> > > > --- 121,137 ----
> > > >   {
> > > >     /* objfile->sections can be already set when reading a mapped symbol
> > > >        file.  I believe that we do need to rebuild the section table in
> > > > !      this case (we rebuild other things derived from the bfd).
> > > > !      DJB - 05-27-2001 
> > > > !      It's in the misc_obstack now, feel free to do what you need to.
> > > > !      All the stuff in objfile that was on the psymbol obstack, but didnt' belong, is in the misc obstack, which 
> > > > !      I think is all the stuff you want to blow away anyway.
> > > > !      */
> > > >   
> > > >     objfile->sections_end = 0;
> > > >     bfd_map_over_sections (objfile->obfd, add_to_objfile_sections, (char *) objfile);
> > > >     objfile->sections = (struct obj_section *)
> > > > !     obstack_finish (&objfile->misc_obstack);
> > > >     objfile->sections_end = objfile->sections + (unsigned long) objfile->sections_end;
> > > >     return (0);
> > > >   }
> > > > *************** allocate_objfile (bfd *abfd, int flags)
> > > > *** 188,193 ****
> > > > --- 191,198 ----
> > > >   	      /* Update pointers to functions to *our* copies */
> > > >   	      obstack_chunkfun (&objfile->psymbol_cache.cache, xmmalloc);
> > > >   	      obstack_freefun (&objfile->psymbol_cache.cache, mfree);
> > > > + 	      obstack_chunkfun (&objfile->misc_obstack, xmmalloc);
> > > > + 	      obstack_freefun (&objfile->misc_obstack, mfree);
> > > >   	      obstack_chunkfun (&objfile->psymbol_obstack, xmmalloc);
> > > >   	      obstack_freefun (&objfile->psymbol_obstack, mfree);
> > > >   	      obstack_chunkfun (&objfile->symbol_obstack, xmmalloc);
> > > > *************** allocate_objfile (bfd *abfd, int flags)
> > > > *** 218,223 ****
> > > > --- 223,231 ----
> > > >   	      obstack_specify_allocation_with_arg (&objfile->psymbol_cache.cache,
> > > >   						   0, 0, xmmalloc, mfree,
> > > >   						   objfile->md);
> > > > + 	      obstack_specify_allocation_with_arg (&objfile->misc_obstack,
> > > > + 						   0, 0, xmmalloc, mfree,
> > > > + 						   objfile->md);
> > > >   	      obstack_specify_allocation_with_arg (&objfile->psymbol_obstack,
> > > >   						   0, 0, xmmalloc, mfree,
> > > >   						   objfile->md);
> > > > *************** allocate_objfile (bfd *abfd, int flags)
> > > > *** 264,269 ****
> > > > --- 272,279 ----
> > > >         objfile->md = NULL;
> > > >         obstack_specify_allocation (&objfile->psymbol_cache.cache, 0, 0,
> > > >   				  xmalloc, xfree);
> > > > +       obstack_specify_allocation (&objfile->misc_obstack, 0, 0, xmalloc,
> > > > + 				  xfree);
> > > >         obstack_specify_allocation (&objfile->psymbol_obstack, 0, 0, xmalloc,
> > > >   				  xfree);
> > > >         obstack_specify_allocation (&objfile->symbol_obstack, 0, 0, xmalloc,
> > > > *************** free_objfile (struct objfile *objfile)
> > > > *** 475,480 ****
> > > > --- 485,491 ----
> > > >   	mfree (objfile->md, objfile->static_psymbols.list);
> > > >         /* Free the obstacks for non-reusable objfiles */
> > > >         free_bcache (&objfile->psymbol_cache);
> > > > +       obstack_free (&objfile->misc_obstack, 0);
> > > >         obstack_free (&objfile->psymbol_obstack, 0);
> > > >         obstack_free (&objfile->symbol_obstack, 0);
> > > >         obstack_free (&objfile->type_obstack, 0);
> > > > Index: objfiles.h
> > > > ===================================================================
> > > > RCS file: /cvs/src/src/gdb/objfiles.h,v
> > > > retrieving revision 1.8
> > > > diff -c -3 -p -w -B -b -r1.8 objfiles.h
> > > > *** objfiles.h	2001/03/06 08:21:11	1.8
> > > > --- objfiles.h	2001/05/29 17:28:00
> > > > *************** struct objfile
> > > > *** 269,274 ****
> > > > --- 269,275 ----
> > > >       /* Obstacks to hold objects that should be freed when we load a new symbol
> > > >          table from this object file. */
> > > >   
> > > > +     struct obstack misc_obstack;	/* Misc stuff */
> > > >       struct obstack psymbol_obstack;	/* Partial symbols */
> > > >       struct obstack symbol_obstack;	/* Full symbols */
> > > >       struct obstack type_obstack;	/* Types */
> > > > 
> > > > -- 
> > > > "I used to be a narrator for bad mimes.
> > > > "-Steven Wright
> > > > 
> > 
> > -- 
> > "I went into a clothes store the other day and a salesman walked
> > up to me and said, "Can I help you?"  and I said "Yeah, do you
> > got anything I like?"  He said, "What do you mean do we have
> > anything you like?"  I said, "You started this."
> > "-Steven Wright
> > 

-- 
"So I figured I'd leave the area, because I had no ties there
anyway except for this girl I was seeing.  We had conflicting
attitudes:  I really wasn't into meditating and she wasn't
really into being alive.  I told her I knew when I was going to
die because my birth certificate has an expiration date.
"-Steven Wright

Re: [RFA]: Add misc_obstack to object files.

[Elena Zannoni]

Daniel Berlin writes:
 > Elena Zannoni <ezannoni@cygnus.com> writes:
 > 
 > > Daniel Berlin writes:
 > > > Elena Zannoni <ezannoni@cygnus.com> writes:
 > > > 
 > > > > Daniel Berlin writes:
 > > > > > 
 > > > > > This way, we stop putting things in the psymbol_obstack that don't
 > > > > > belong.  
 > > > > > 
 > > > > 
 > > > > Dan, can you elaborate a bit on why we need this?
 > > > Because these things don't belong in the psymbol obstack.
 > > > They are section offsets, not partial symbols.
 > > > 
 > > 
 > > Dan, I am really sorry, but still I cannot see a real reason for this
 > > change emerging from your mail. 
 > 
 > Um.
 > Okay.
 > According to objfiles.h:
 > 
 >     struct obstack psymbol_obstack;     /* Partial symbols */
 >     struct obstack symbol_obstack;      /* Full symbols */
 >     struct obstack type_obstack;        /* Types */
 > 
 > 
 > Notice it doesn't say that section offsets, or other random junk,
 > should be on the psymbol_obstack.
 > It says "Partial symbols".
 > Now, if you want to remove the partial symbols, for that object file,
 > theoretically, you just remove the psymbol_obstack.  However, because
 > we allocate other random things, like section offset tables, etc,
 > which have zip to do with partial symbols, on that obstack, we won't
 > remove just the partial symbols by removing that obstack.  We'll blow
 > away the section offset table, the psymtab structures, etc.
 > This should not be occurring.
 > It makes as much sense as allocating object file section offsets on the
 > type_obstack, which is for types only. That is to say, none.
 > 

Yes, and this is the bug I was alluding to. You mentioned you observed
that things like the section tables were freed too early. When does
this occur? Did you try to move around the call to
free_obstack(psymbol_obstack)? What motivated you to try and do that?
That's really what I am asking.

 > It's the equivalent of having a trash bin marked "white paper only",
 > and having people knowing throw all kinds of colored paper in there,
 > for lack of a better place to throw colored paper.
 > They don't belong.
 > Not only that, but if you later wanted to remove the white paper, you'd have to sort out
 > the colored paper, and do something with it, first.
 > 
 > I'm just adding a bin for colored paper, so people will put that stuff
 > in there instead in the first place, and it will be plainly clear that they are supposed
 > to be doing so.
 > 
 > 
 > > You are doing this in response to some bug you saw, I assume, but what that
 > > bug is has not been explained.
 > No, i'm doing it because partial symbols belong on the psymbol
 > obstack, but section offsets, and other random things don't.
 > In practice, we've not followed this, because nobody bothered to
 > create somewhere *else* to put them. I'm attempting to bring us
 > to doing what we should have been doing in the first place, by
 > creating this place to put them.
 > 

Yes, true.

 > Had I been trying to fix a bug, i would explain what the bug was, and
 > where it showed up.
 > 
 > This is not a bug, in that nothing is specifically *broken*. It's
 > perfectly okay to allocate these structures on that obstack, given
 > that gdb never frees the obstack, it's just not in line with what the
 > comments say, and the purpose of the psymbol obstack.
 > 

Isn't the psymbol_obstack freed when you re-read symbols in? 

 > > 
 > > 
 > > > > Why are you removing
 > > > > the partial symbol table from the psymbol_objstack?
 > > > I'm not. At all in fact.
 > > > I'm specifically trying to make it so *all* that is in the
 > > > psymbol_obstack is the partial symbol table.
 > > > we've been stuffing random stuff like section offsets into the
 > > > psymbol_obstack, because it was handy.
 > > > This is wrong.
 > > > If we need a misc place to put info like section offsets, that isn't
 > > > large enough to deserve it's own obstack on it's own, then all the
 > > > misc stuff together should go in a misc_obstack.
 > > 
 > > Then your patch includes a diff that is unrelated.
 > Um, how so?
 > Please point out the portion of the diff unrelated.
 > The only thing even related to psymtabs there is the fact that they
 > psymtab structure itself is allocated on the misc obstack, since it
 > isn't a partial symbol either. It's a partial symbol table structure,
 > containing pointers to partial symbols. 

Yes, that's the one.

I would think that the psymtab itself is better coupled with
psymbol_objstack, than misc_obstack.  
I would think it safer to free both of them or none, than to risk
freeing the section_offsets and also the psymbol table by mistake.

 > The actual partial symbols that fill that table are still allocated on
 > the psymbol_obstack.
 > As they should be.

yes, but looking at the way the symbol table is allocated, it follows
the same logic, symbol_obstack includes the symtab itself as well.

I mean, the real problem that you are trying to address is that you
need a different lifetime for psymbols vs psymtab, and for psymbols vs
section_offsets. So, why is this necessary? Are you addressing a
limitation that you have found while trying to do something else? Why
is it a problem that section_offsets, psymbols and psymtab have the
same lifetime?
[I am not arguing that section offsets are logically related to psymbols]

 > > 
 > > > 
 > > > >  Was this intended?
 > > > > There are several other things that get allocated on the
 > > > > psymbol_objstack, for instance look in xcoffread.c, somread.c,
 > > > > etc. Why just remove the section offset stuff?
 > > > Because I haven't gotten to the others yet.
 > > > And there is no harm in taking time to make sure it gets done right.
 > > > 
 > > 
 > > If you have a roadmap in mind, you should explain it when you submit
 > > the patch.
 > 
 > I have no roadmap for when i'd be getting to that.
 > Eventually.
 > I could do them all now if it helps, but it'll make the patch bigger.
 > 

I would suggest that you put the section offsets stuff on its own
separate obstack for now, but do that across the board, to avoid
inconsistencies. That would be a self contained patch.
Follow up patches would move other pieces.

Elena


 > 
 > > 
 > > > > 
 > > > > If your intent was to change the allocation of the section offset
 > > > > information, from psymbol_obstack to misc_obstack, why not modify also
 > > > > the same allocations done in xcoffread.c, elfread.c, somread.c?
 > > > Because i haven't gotten there yet.
 > > > :)
 > > > I did it as I saw them.
 > > > 
 > > > In actuality, what i was doing was freeing the psymbol obstack when we
 > > > were completely done with partial symbols, and seeing what broke.
 > > > They never broke, so i never noticed them.
 > > > 
 > > > When i submit a large patch that does all this in one fell swoop,
 > > > someone would say to break it down.
 > > > So consider this a first step, rather than a done deal.
 > > > 
 > > 
 > > I am encouraging you to resubmit the patch accompanied by coherent
 > > explanation and rationale.
 > I believe you are misunderstanding the purpose of the patch, and what
 > it does, or some portion of it.
 > Please let me know if the above doesn't clear it up.
 > 
 > 
 > > 
 > > Elena
 > > 
 > > 
 > > > > 
 > > > > Thanks
 > > > > Elena
 > > > > 
 > > > > 
 > > > > > 2001-05-27  Daniel Berlin  <dan@cgsoftware.com>
 > > > > > 
 > > > > > 	* symfile.c (default_symfile_offsets): Allocate in misc_obstack.
 > > > > > 	(reread_symbols): Handle misc_obstack too, and use it where
 > > > > > 	psymbol_obstack didn't belong. 
 > > > > > 	(allocate_psymtab): Ditto.
 > > > > > 
 > > > > > 	* objfiles.c (add_to_objfile_sections):  Use misc_obstack, not psymbol_obstack.
 > > > > > 	(build_objfile_section_table): Ditto.
 > > > > > 	(free_objfile): Free the misc_obstack.
 > > > > > 	(allocate_objfile): Setup misc_obstack too.
 > > > > > 
 > > > > > 	* objfiles.h: Add misc_obstack to object file.
 > > > > > 
 > > > > > Index: symfile.c
 > > > > > ===================================================================
 > > > > > RCS file: /cvs/src/src/gdb/symfile.c,v
 > > > > > retrieving revision 1.32
 > > > > > diff -c -3 -p -w -B -b -r1.32 symfile.c
 > > > > > *** symfile.c	2001/05/10 15:33:21	1.32
 > > > > > --- symfile.c	2001/05/29 17:27:51
 > > > > > *************** default_symfile_offsets (struct objfile 
 > > > > > *** 500,506 ****
 > > > > >   
 > > > > >     objfile->num_sections = SECT_OFF_MAX;
 > > > > >     objfile->section_offsets = (struct section_offsets *)
 > > > > > !     obstack_alloc (&objfile->psymbol_obstack, SIZEOF_SECTION_OFFSETS);
 > > > > >     memset (objfile->section_offsets, 0, SIZEOF_SECTION_OFFSETS);
 > > > > >   
 > > > > >     /* Now calculate offsets for section that were specified by the
 > > > > > --- 500,506 ----
 > > > > >   
 > > > > >     objfile->num_sections = SECT_OFF_MAX;
 > > > > >     objfile->section_offsets = (struct section_offsets *)
 > > > > > !     obstack_alloc (&objfile->misc_obstack, SIZEOF_SECTION_OFFSETS);
 > > > > >     memset (objfile->section_offsets, 0, SIZEOF_SECTION_OFFSETS);
 > > > > >   
 > > > > >     /* Now calculate offsets for section that were specified by the
 > > > > > *************** reread_symbols (void)
 > > > > > *** 1679,1684 ****
 > > > > > --- 1679,1685 ----
 > > > > >   
 > > > > >   	      /* Free the obstacks for non-reusable objfiles */
 > > > > >   	      free_bcache (&objfile->psymbol_cache);
 > > > > > + 	      obstack_free (&objfile->misc_obstack, 0);
 > > > > >   	      obstack_free (&objfile->psymbol_obstack, 0);
 > > > > >   	      obstack_free (&objfile->symbol_obstack, 0);
 > > > > >   	      obstack_free (&objfile->type_obstack, 0);
 > > > > > *************** reread_symbols (void)
 > > > > > *** 1704,1709 ****
 > > > > > --- 1705,1712 ----
 > > > > >   	         it is empty.  */
 > > > > >   	      obstack_specify_allocation (&objfile->psymbol_cache.cache, 0, 0,
 > > > > >   					  xmalloc, xfree);
 > > > > > + 	      obstack_specify_allocation (&objfile->misc_obstack, 0, 0,
 > > > > > + 					  xmalloc, xfree);
 > > > > >   	      obstack_specify_allocation (&objfile->psymbol_obstack, 0, 0,
 > > > > >   					  xmalloc, xfree);
 > > > > >   	      obstack_specify_allocation (&objfile->symbol_obstack, 0, 0,
 > > > > > *************** reread_symbols (void)
 > > > > > *** 1719,1725 ****
 > > > > >   	      /* We use the same section offsets as from last time.  I'm not
 > > > > >   	         sure whether that is always correct for shared libraries.  */
 > > > > >   	      objfile->section_offsets = (struct section_offsets *)
 > > > > > ! 		obstack_alloc (&objfile->psymbol_obstack, SIZEOF_SECTION_OFFSETS);
 > > > > >   	      memcpy (objfile->section_offsets, offsets, SIZEOF_SECTION_OFFSETS);
 > > > > >   	      objfile->num_sections = num_offsets;
 > > > > >   
 > > > > > --- 1722,1728 ----
 > > > > >   	      /* We use the same section offsets as from last time.  I'm not
 > > > > >   	         sure whether that is always correct for shared libraries.  */
 > > > > >   	      objfile->section_offsets = (struct section_offsets *)
 > > > > > ! 		obstack_alloc (&objfile->misc_obstack, SIZEOF_SECTION_OFFSETS);
 > > > > >   	      memcpy (objfile->section_offsets, offsets, SIZEOF_SECTION_OFFSETS);
 > > > > >   	      objfile->num_sections = num_offsets;
 > > > > >   
 > > > > > *************** allocate_psymtab (char *filename, struct
 > > > > > *** 1981,1993 ****
 > > > > >         objfile->free_psymtabs = psymtab->next;
 > > > > >       }
 > > > > >     else
 > > > > > !     psymtab = (struct partial_symtab *)
 > > > > > !       obstack_alloc (&objfile->psymbol_obstack,
 > > > > > ! 		     sizeof (struct partial_symtab));
 > > > > >   
 > > > > >     memset (psymtab, 0, sizeof (struct partial_symtab));
 > > > > > !   psymtab->filename = obsavestring (filename, strlen (filename),
 > > > > > ! 				    &objfile->psymbol_obstack);
 > > > > >     psymtab->symtab = NULL;
 > > > > >   
 > > > > >     /* Prepend it to the psymtab list for the objfile it belongs to.
 > > > > > --- 1984,1993 ----
 > > > > >         objfile->free_psymtabs = psymtab->next;
 > > > > >       }
 > > > > >     else
 > > > > > !     psymtab = (struct partial_symtab *) obstack_alloc (&objfile->misc_obstack, sizeof (struct partial_symtab));
 > > > > >   
 > > > > >     memset (psymtab, 0, sizeof (struct partial_symtab));
 > > > > > !   psymtab->filename = obsavestring (filename, strlen(filename), &objfile->misc_obstack);
 > > > > >     psymtab->symtab = NULL;
 > > > > >   
 > > > > >     /* Prepend it to the psymtab list for the objfile it belongs to.
 > > > > > Index: objfiles.c
 > > > > > ===================================================================
 > > > > > RCS file: /cvs/src/src/gdb/objfiles.c,v
 > > > > > retrieving revision 1.15
 > > > > > diff -c -3 -p -w -B -b -r1.15 objfiles.c
 > > > > > *** objfiles.c	2001/03/06 08:21:11	1.15
 > > > > > --- objfiles.c	2001/05/29 17:27:57
 > > > > > *************** add_to_objfile_sections (bfd *abfd, sec_
 > > > > > *** 96,102 ****
 > > > > >     section.ovly_mapped = 0;
 > > > > >     section.addr = bfd_section_vma (abfd, asect);
 > > > > >     section.endaddr = section.addr + bfd_section_size (abfd, asect);
 > > > > > !   obstack_grow (&objfile->psymbol_obstack, (char *) &section, sizeof (section));
 > > > > >     objfile->sections_end = (struct obj_section *) (((unsigned long) objfile->sections_end) + 1);
 > > > > >   }
 > > > > >   
 > > > > > --- 96,102 ----
 > > > > >     section.ovly_mapped = 0;
 > > > > >     section.addr = bfd_section_vma (abfd, asect);
 > > > > >     section.endaddr = section.addr + bfd_section_size (abfd, asect);
 > > > > > !   obstack_grow (&objfile->misc_obstack, (char *) &section, sizeof (section));
 > > > > >     objfile->sections_end = (struct obj_section *) (((unsigned long) objfile->sections_end) + 1);
 > > > > >   }
 > > > > >   
 > > > > > *************** build_objfile_section_table (struct objf
 > > > > > *** 121,134 ****
 > > > > >   {
 > > > > >     /* objfile->sections can be already set when reading a mapped symbol
 > > > > >        file.  I believe that we do need to rebuild the section table in
 > > > > > !      this case (we rebuild other things derived from the bfd), but we
 > > > > > !      can't free the old one (it's in the psymbol_obstack).  So we just
 > > > > > !      waste some memory.  */
 > > > > >   
 > > > > >     objfile->sections_end = 0;
 > > > > >     bfd_map_over_sections (objfile->obfd, add_to_objfile_sections, (char *) objfile);
 > > > > >     objfile->sections = (struct obj_section *)
 > > > > > !     obstack_finish (&objfile->psymbol_obstack);
 > > > > >     objfile->sections_end = objfile->sections + (unsigned long) objfile->sections_end;
 > > > > >     return (0);
 > > > > >   }
 > > > > > --- 121,137 ----
 > > > > >   {
 > > > > >     /* objfile->sections can be already set when reading a mapped symbol
 > > > > >        file.  I believe that we do need to rebuild the section table in
 > > > > > !      this case (we rebuild other things derived from the bfd).
 > > > > > !      DJB - 05-27-2001 
 > > > > > !      It's in the misc_obstack now, feel free to do what you need to.
 > > > > > !      All the stuff in objfile that was on the psymbol obstack, but didnt' belong, is in the misc obstack, which 
 > > > > > !      I think is all the stuff you want to blow away anyway.
 > > > > > !      */
 > > > > >   
 > > > > >     objfile->sections_end = 0;
 > > > > >     bfd_map_over_sections (objfile->obfd, add_to_objfile_sections, (char *) objfile);
 > > > > >     objfile->sections = (struct obj_section *)
 > > > > > !     obstack_finish (&objfile->misc_obstack);
 > > > > >     objfile->sections_end = objfile->sections + (unsigned long) objfile->sections_end;
 > > > > >     return (0);
 > > > > >   }
 > > > > > *************** allocate_objfile (bfd *abfd, int flags)
 > > > > > *** 188,193 ****
 > > > > > --- 191,198 ----
 > > > > >   	      /* Update pointers to functions to *our* copies */
 > > > > >   	      obstack_chunkfun (&objfile->psymbol_cache.cache, xmmalloc);
 > > > > >   	      obstack_freefun (&objfile->psymbol_cache.cache, mfree);
 > > > > > + 	      obstack_chunkfun (&objfile->misc_obstack, xmmalloc);
 > > > > > + 	      obstack_freefun (&objfile->misc_obstack, mfree);
 > > > > >   	      obstack_chunkfun (&objfile->psymbol_obstack, xmmalloc);
 > > > > >   	      obstack_freefun (&objfile->psymbol_obstack, mfree);
 > > > > >   	      obstack_chunkfun (&objfile->symbol_obstack, xmmalloc);
 > > > > > *************** allocate_objfile (bfd *abfd, int flags)
 > > > > > *** 218,223 ****
 > > > > > --- 223,231 ----
 > > > > >   	      obstack_specify_allocation_with_arg (&objfile->psymbol_cache.cache,
 > > > > >   						   0, 0, xmmalloc, mfree,
 > > > > >   						   objfile->md);
 > > > > > + 	      obstack_specify_allocation_with_arg (&objfile->misc_obstack,
 > > > > > + 						   0, 0, xmmalloc, mfree,
 > > > > > + 						   objfile->md);
 > > > > >   	      obstack_specify_allocation_with_arg (&objfile->psymbol_obstack,
 > > > > >   						   0, 0, xmmalloc, mfree,
 > > > > >   						   objfile->md);
 > > > > > *************** allocate_objfile (bfd *abfd, int flags)
 > > > > > *** 264,269 ****
 > > > > > --- 272,279 ----
 > > > > >         objfile->md = NULL;
 > > > > >         obstack_specify_allocation (&objfile->psymbol_cache.cache, 0, 0,
 > > > > >   				  xmalloc, xfree);
 > > > > > +       obstack_specify_allocation (&objfile->misc_obstack, 0, 0, xmalloc,
 > > > > > + 				  xfree);
 > > > > >         obstack_specify_allocation (&objfile->psymbol_obstack, 0, 0, xmalloc,
 > > > > >   				  xfree);
 > > > > >         obstack_specify_allocation (&objfile->symbol_obstack, 0, 0, xmalloc,
 > > > > > *************** free_objfile (struct objfile *objfile)
 > > > > > *** 475,480 ****
 > > > > > --- 485,491 ----
 > > > > >   	mfree (objfile->md, objfile->static_psymbols.list);
 > > > > >         /* Free the obstacks for non-reusable objfiles */
 > > > > >         free_bcache (&objfile->psymbol_cache);
 > > > > > +       obstack_free (&objfile->misc_obstack, 0);
 > > > > >         obstack_free (&objfile->psymbol_obstack, 0);
 > > > > >         obstack_free (&objfile->symbol_obstack, 0);
 > > > > >         obstack_free (&objfile->type_obstack, 0);
 > > > > > Index: objfiles.h
 > > > > > ===================================================================
 > > > > > RCS file: /cvs/src/src/gdb/objfiles.h,v
 > > > > > retrieving revision 1.8
 > > > > > diff -c -3 -p -w -B -b -r1.8 objfiles.h
 > > > > > *** objfiles.h	2001/03/06 08:21:11	1.8
 > > > > > --- objfiles.h	2001/05/29 17:28:00
 > > > > > *************** struct objfile
 > > > > > *** 269,274 ****
 > > > > > --- 269,275 ----
 > > > > >       /* Obstacks to hold objects that should be freed when we load a new symbol
 > > > > >          table from this object file. */
 > > > > >   
 > > > > > +     struct obstack misc_obstack;	/* Misc stuff */
 > > > > >       struct obstack psymbol_obstack;	/* Partial symbols */
 > > > > >       struct obstack symbol_obstack;	/* Full symbols */
 > > > > >       struct obstack type_obstack;	/* Types */
 > > > > > 
 > > > > > -- 
 > > > > > "I used to be a narrator for bad mimes.
 > > > > > "-Steven Wright
 > > > > > 
 > > > 
 > > > -- 
 > > > "I went into a clothes store the other day and a salesman walked
 > > > up to me and said, "Can I help you?"  and I said "Yeah, do you
 > > > got anything I like?"  He said, "What do you mean do we have
 > > > anything you like?"  I said, "You started this."
 > > > "-Steven Wright
 > > > 
 > 
 > -- 
 > "So I figured I'd leave the area, because I had no ties there
 > anyway except for this girl I was seeing.  We had conflicting
 > attitudes:  I really wasn't into meditating and she wasn't
 > really into being alive.  I told her I knew when I was going to
 > die because my birth certificate has an expiration date.
 > "-Steven Wright
 > 

Re: [RFA]: Add misc_obstack to object files.

[Daniel Berlin]

Elena Zannoni <ezannoni@cygnus.com> writes:

> Daniel Berlin writes:
> > Elena Zannoni <ezannoni@cygnus.com> writes:
> > 
> > > Daniel Berlin writes:
> > > > Elena Zannoni <ezannoni@cygnus.com> writes:
> > > > 
> > > > > Daniel Berlin writes:
> > > > > > 
> > > > > > This way, we stop putting things in the psymbol_obstack that don't
> > > > > > belong.  
> > > > > > 
> > > > > 
> > > > > Dan, can you elaborate a bit on why we need this?
> > > > Because these things don't belong in the psymbol obstack.
> > > > They are section offsets, not partial symbols.
> > > > 
> > > 
> > > Dan, I am really sorry, but still I cannot see a real reason for this
> > > change emerging from your mail. 
> > 
> > Um.
> > Okay.
> > According to objfiles.h:
> > 
> >     struct obstack psymbol_obstack;     /* Partial symbols */
> >     struct obstack symbol_obstack;      /* Full symbols */
> >     struct obstack type_obstack;        /* Types */
> > 
> > 
> > Notice it doesn't say that section offsets, or other random junk,
> > should be on the psymbol_obstack.
> > It says "Partial symbols".
> > Now, if you want to remove the partial symbols, for that object file,
> > theoretically, you just remove the psymbol_obstack.  However, because
> > we allocate other random things, like section offset tables, etc,
> > which have zip to do with partial symbols, on that obstack, we won't
> > remove just the partial symbols by removing that obstack.  We'll blow
> > away the section offset table, the psymtab structures, etc.
> > This should not be occurring.
> > It makes as much sense as allocating object file section offsets on the
> > type_obstack, which is for types only. That is to say, none.
> > 
> 
> Yes, and this is the bug I was alluding to. You mentioned you observed
> that things like the section tables were freed too early. When does
> this occur?

When you attempt to free the psymbol obstack after you are done  with
all the psymbols for an objfile.  However, gdb currently doesn't do
this. This is part of the reason you can't.

>  Did you try to move around the call to
> free_obstack(psymbol_obstack)?

There are only calls to do this type of thing when we remove object
files or reread symbols.

It would, of course, to make sense to free the partial symbols for an
objfile once we were sure all the symtabs for that objfile had been
read in.
This does not currently occur.  The bug occurs when you attempt to do
this.
The actual reason it never occurs in gdb is because the stabs reader
incorrectly expects partial symbols 
to live past the readin of full symbols (why would you want partial
symbols when you have full ones?), in order to do some duplicate
elimination the cheap, easy, and stabs specific, way.
It does this at the expense of every other symbol reader, since if you
attempt to free the psymbol obstack for stabs, even after you are done
with all the partial symbols for a given objfile, you'll start seeing
weird stabs reader errors.
However, this I consider a seperate problem, since gdb currently
doesn't ever free the psymbol obstack except when it frees objfiles.

>  What motivated you to try and do that?
The fact that we waste effectively double the memory to read symbols
for everything except stabs, because none of the other symbol readers
assume the psymtabs will live past complete symtab conversion, and
thus, assume they will be freed.   The STABS reader happens to
eliminate enough psymbols through it's cheap easy method that you
don't notice the fact that it's keeping all the psymbols around, never
freeing them.

Besides attacking this part of problem by fixing the stabs reader, 
you must also make it so you can actually free the psymbol obstack when you
are done with all the psymtabs for an objfile, without affecting
anything else about that objfile.  I.E. make it so the psymbol_obstack
only contains psymbols.
Otherwise, fixing the stabs reader does you no good, since you still
will blow away unrelated things when trying to free the psymbols.

So in order to fix the problem of keeping psymbols around until
their objfile goes away, rather than until the symtabs for that
objfile are all read in (Or better yet, until a given psymab is
converted into a symtab), I need to start with the small things like
moving the structures out of the psymbol_obstack.
> That's really what I am asking.
> 
> > It's the equivalent of having a trash bin marked "white paper only",
> > and having people knowing throw all kinds of colored paper in there,
> > for lack of a better place to throw colored paper.
> > They don't belong.
> > Not only that, but if you later wanted to remove the white paper, you'd have to sort out
> > the colored paper, and do something with it, first.
> > 
> > I'm just adding a bin for colored paper, so people will put that stuff
> > in there instead in the first place, and it will be plainly clear that they are supposed
> > to be doing so.
> > 
> > 
> > > You are doing this in response to some bug you saw, I assume, but what that
> > > bug is has not been explained.
> > No, i'm doing it because partial symbols belong on the psymbol
> > obstack, but section offsets, and other random things don't.
> > In practice, we've not followed this, because nobody bothered to
> > create somewhere *else* to put them. I'm attempting to bring us
> > to doing what we should have been doing in the first place, by
> > creating this place to put them.
> > 
> 
> Yes, true.
> 
> > Had I been trying to fix a bug, i would explain what the bug was, and
> > where it showed up.
> > 
> > This is not a bug, in that nothing is specifically *broken*. It's
> > perfectly okay to allocate these structures on that obstack, given
> > that gdb never frees the obstack, it's just not in line with what the
> > comments say, and the purpose of the psymbol obstack.
> > 
> 
> Isn't the psymbol_obstack freed when you re-read symbols in? 
Yes.
And when you free objfiles.
However, this is not really it's minimal lifetime.
The usefulness of a psymbol_obstack for an objfile ends the second
you've "converted" (i put it in quotes since conversion usually
involves transforming one thing into a nother, where here we are
really effectively copying, and transforming the copy, since we never
remove the original) all the psymtabs into symtabs.

> 
> > > 
> > > 
> > > > > Why are you removing
> > > > > the partial symbol table from the psymbol_objstack?
> > > > I'm not. At all in fact.
> > > > I'm specifically trying to make it so *all* that is in the
> > > > psymbol_obstack is the partial symbol table.
> > > > we've been stuffing random stuff like section offsets into the
> > > > psymbol_obstack, because it was handy.
> > > > This is wrong.
> > > > If we need a misc place to put info like section offsets, that isn't
> > > > large enough to deserve it's own obstack on it's own, then all the
> > > > misc stuff together should go in a misc_obstack.
> > > 
> > > Then your patch includes a diff that is unrelated.
> > Um, how so?
> > Please point out the portion of the diff unrelated.
> > The only thing even related to psymtabs there is the fact that they
> > psymtab structure itself is allocated on the misc obstack, since it
> > isn't a partial symbol either. It's a partial symbol table structure,
> > containing pointers to partial symbols. 
> 
> Yes, that's the one.
> 
> I would think that the psymtab itself is better coupled with
> psymbol_objstack, than misc_obstack.  

Okay, that's fine.


> I would think it safer to free both of them or none, than to risk
> freeing the section_offsets and also the psymbol table by mistake.

Sure.
> 
> > The actual partial symbols that fill that table are still allocated on
> > the psymbol_obstack.
> > As they should be.
> 
> yes, but looking at the way the symbol table is allocated, it follows
> the same logic, symbol_obstack includes the symtab itself as well.

Real symbols are different. Their lifetime really ends with the
objfile. Partial symbols are just there until we have a need to read
all the real symbols. So their lifetime is different.

> 
> I mean, the real problem that you are trying to address is that you
> need a different lifetime for psymbols vs psymtab, and for psymbols vs
> section_offsets. So, why is this necessary? 

I think i've explained this above, but in different parts of the
message so, for clarity's sake, this particular thing is necessary because:
The lifetime of psymbols for an objfile is until all the symtabs for
that objfile are read in (Theoretically, if you were careful, you
could make the lifetime until those psymbols are converted to symbols,
but it's tricky, because of how obstacks work. The whole freeing
everything that came after the object you want to free stuff). Once
this is done, the psymbols serve 0 purpose. Provably, no lookup that
fails on the symbols could work on the psymbols, unless your reader is
broken (since they are coming from the same info). 
> Are you addressing a
> limitation that you have found while trying to do something else?
Yes.
This is the first step of addressing the limitation that we keep
psymbols around longer than necessary.  This becomes a factor for
STABS when you have very large programs (IE duplicate symbol
elimination doesn't save you, because you really have 500k distinct
symbols and types), and for other debug formats which don't have
linker support for duplicate elimination, much quicker.

Even with a gdb compiled with dwarf2, where gdb isn't that large of a
program in terms of psymbols (because c has few duplicates compare to
C++, and because C++ programs have often have more of the things that
we generate psymbols for) shows the following, after all symtabs are read in (IE when
psymbols are, bye, definition, useless)

(top-gdb) maintenance print statistics
Statistics for '/buildspace2/dwarf2gdbtree/src/gdb/./gdbdwarf2':
  Number of "minimal" symbols read: 7149
  Number of "partial" symbols read: 289144
  Number of "full" symbols read: 445652
  Number of "types" defined: 162155
  Total memory used for psymbol obstack: 12389013
  Total memory used for psymbol cache: 745176
  Total memory used for symbol obstack: 35083179
  Total memory used for type obstack: 28099722

Out of 75 meg of memory, we are wasting 1/6th on psymbols.
This is probably average for C programs.

For C++ programs, you tend to see a psymbol obstack equal in size to
the symbol obstack.
In other words, we waste double the memory on symbols.

> Why
> is it a problem that section_offsets, psymbols and psymtab have the
> same lifetime?
section_offsets logically have the lifetime of the objfile.
psymbols and the associated psymtabs have a lifetime that lasts
exactly until the full symbols for those psymbols are read in (IE the
psymtab is converted to a symtab).
Right now, the we treat them like they last until the objfile goes
away.
I'm working on treating them like they last until all the symbols for
a given objfile are read in (which happens fairly quickly unless you
have a huge, monolithic program).
This is because treating them like they have the lifetime they really
do would require being able to free all the psymbols for a given
psymtab without touching any other psymbols.  Because of how obstacks
work, doing this would require not using obstacks for psymbols, or
rather, making the obstack part of the psymtab (so you can free all
the memory associated with the psymtab without touching anything else)
Eventually, that is the goal, but that's way off.
Since it is a complex change to do that anyway, and it's more of an 
incremental step from being able to free psymbols at *some particular* point
before the objfile goes away, this actually gets us closer to being
able to do that.

> [I am not arguing that section offsets are logically related to psymbols]
> 
> > > 
> > > > 
> > > > >  Was this intended?
> > > > > There are several other things that get allocated on the
> > > > > psymbol_objstack, for instance look in xcoffread.c, somread.c,
> > > > > etc. Why just remove the section offset stuff?
> > > > Because I haven't gotten to the others yet.
> > > > And there is no harm in taking time to make sure it gets done right.
> > > > 
> > > 
> > > If you have a roadmap in mind, you should explain it when you submit
> > > the patch.
> > 
> > I have no roadmap for when i'd be getting to that.
> > Eventually.
> > I could do them all now if it helps, but it'll make the patch bigger.
> > 
> 
> I would suggest that you put the section offsets stuff on its own
> separate obstack for now, but do that across the board, to avoid
> inconsistencies. That would be a self contained patch.
> Follow up patches would move other pieces.
Okeydokey.

> 
> Elena


-- 
"When I was a kid, I went to the store and asked the guy, "Do you
have any toy train schedules?"
"-Steven Wright