pending/1010: [RFA] Runtime Dwarf2 CFI engine cleanup

[Michal Ludvig <mludvig at suse dot cz>]

>Number:         1010
>Category:       pending
>Synopsis:       [RFA] Runtime Dwarf2 CFI engine cleanup
>Confidential:   yes
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          change-request
>Submitter-Id:   unknown
>Arrival-Date:   Fri Jan 31 06:18:00 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator:     
>Release:        
>Organization:
>Environment:
>Description:
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 Hi all,
 the attached is a fix for the problem described here:
 http://sources.redhat.com/ml/gdb/2002-12/msg00246.html
 
 I've created a new function cleanup_cfi() in dwarf2cfi.c that deletes 
 all CIEs and FDEs of objfiles removed later by objfile_purge_solibs().
 So far it works fine but I don't know how should I correctly call it.
 For now I put the call directly to run_command():
 
 static void
 run_command (char *args, int from_tty)
 {
    [...]
    clear_breakpoint_hit_counts ();
 
    cleanup_cfi ();    /* <=== HERE */
 
    objfile_purge_solibs ();
 
    do_run_cleanups (NULL);
 
    reopen_exec_file ();
    reread_symbols ();
    [...]
 }
 
 I know it isn't the right solution because it would require linking of 
 dwarf2cfi.o to all targets. If I would wrap it by #ifdef X86_64 ... 
 #endif it still isn't perfect, because other archs will hopefully use 
 CFI in the future as well.
 
 I was thinking about defining something like USE_DWARF2CFI for each 
 target that use it in their config/whatever file...? Is it a way to go?
 
 I can't attach this function to run_cleanup_chain, because I need to 
 call cleanup_cfi() before objfile_purge_solibs() and also because 
 do_run_cleanups() finally destroys the contents of run_cleanup_chain and 
 finally because I don't know how (when/where) to attach cleanup_cfi() to 
 run_cleanup_chain.
 
 Could someone please tell me what is the cleanest way to call 
 cleanup_cfi()? Thanks.
 
 Michal Ludvig
 -- 
 * SuSE CR, s.r.o     * mludvig@suse.cz
 * (+420) 296.545.373 * http://www.suse.cz
 
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 Index: dwarf2cfi.h
 ===================================================================
 RCS file: /cvs/src/src/gdb/dwarf2cfi.c,v
 retrieving revision 1.16
 diff -u -p -r1.16 dwarf2cfi.h
 --- dwarf2cfi.h	19 Jul 2002 09:40:51 -0000	1.16
 +++ dwarf2cfi.h	20 Dec 2002 15:14:21 -0000
 @@ -64,6 +64,12 @@ struct cie_unit
  
    /* Next in chain.  */
    struct cie_unit *next;
 +
 +  /* Keep or destroy this CIE on a new run? */
 +  int keep;
 +
 +  /* How many FDEs refer to this CIE? */
 +  int refs;
  };
  
  /* Frame Description Entry.  */
 Index: dwarf2cfi.c
 ===================================================================
 RCS file: /cvs/src/src/gdb/dwarf2cfi.c,v
 retrieving revision 1.16
 diff -u -p -r1.16 dwarf2cfi.c
 --- dwarf2cfi.c	19 Jul 2002 09:40:51 -0000	1.16
 +++ dwarf2cfi.c	20 Dec 2002 15:14:21 -0000
 @@ -317,6 +326,86 @@ frame_state_alloc (void)
      (struct frame_state_reg *) obstack_alloc (&unwind_tmp_obstack, regs_size);
    memset (fs->regs.reg, 0, regs_size);
    return fs;
 +}
 +
 +void
 +cleanup_cfi (void *name)
 +{
 +  struct objfile *ofp;
 +  struct cie_unit *cie, *cie_prev;
 +  int fde_index=0, fde_free=0;
 +  
 +  cie = cie_chunks;
 +  while (cie)
 +  {
 +	  cie->refs = 0;
 +	  cie->keep = 0;
 +	  cie = cie->next;
 +  }
 +
 +  /* Mark all unwanted CIEs. */
 +  ALL_OBJFILES (ofp)
 +  {
 +	  if (!(ofp->flags & OBJF_USERLOADED) && (ofp->flags & OBJF_SHARED))
 +		  printf ("\tRemoving %s...\n", ofp->name);
 +	  else
 +	  {
 +		  printf ("\tKeeping %s...\n", ofp->name);
 +		  cie = cie_chunks;
 +		  while(cie)
 +		  {
 +			  if (cie->objfile == ofp)
 +				  cie->keep = 1;
 +			  cie = cie->next;
 +		  }
 +	  }
 +  }
 +
 +  /* Remove all FDEs pointing to unwanted CIEs. */
 +  for (fde_index = 0, fde_free=0; 
 +	fde_index < fde_chunks.elems; 
 +	fde_index++, fde_free++)
 +  {
 +	  if (!fde_chunks.array[fde_index]->cie_ptr->keep)
 +	  {
 +		  fde_free--;
 +		  continue;
 +	  }
 +	  else if (fde_free < fde_index)
 +		  fde_chunks.array[fde_free] = fde_chunks.array[fde_index];
 +	  fde_chunks.array[fde_free]->cie_ptr->refs++;
 +  }
 +  fde_chunks.elems = fde_free;
 +
 +  /* Remove all unwanted CIEs. */
 +  cie = cie_chunks;
 +  cie_prev = NULL;
 +  while (cie)
 +  {
 +	  struct cie_unit *cie_tmp;
 +	  
 +	  if (! cie->keep || !cie->refs)
 +	  {
 +		  cie_tmp = cie;
 +		  if (cie_prev == NULL)
 +		  {
 +			  cie_chunks = cie->next;
 +			  cie = cie_chunks;
 +		  }
 +		  else 
 +		  {
 +			  cie_prev->next = cie->next;
 +			  cie = cie->next;
 +		  }
 +		  /* cie_prev must remain unchanged. */
 +		  xfree (cie_tmp);
 +	  }
 +	  else
 +	  {
 +		  cie_prev = cie;
 +		  cie = cie->next;
 +	  }
 +  }
  }
  
  static void
 
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