Re: PATCH: PR ld/3191: Linker failed to handle DW_FORM_ref_addr properly

["H. J. Lu" <hjl at lucon dot org>]

On Wed, Sep 27, 2006 at 05:21:15PM -0700, Jim Wilson wrote:
> On Thu, 2006-09-21 at 08:03 -0700, H. J. Lu wrote:
> > 	PR ld/3191
> > 	* dwarf2.c (_bfd_dwarf2_find_nearest_line): Adjust debug_info
> > 	section vma when needed.
> 
> I'm willing to review a patch for this bug report, but I am still unable
> to reproduce the bug, same as last week.  I tried the object files in
> the bug report, but I can't get them to fail.  I also went so far as to
> try to build kdesvn, but gave up because it required too many other
> unfamiliar packages.
> 

Jim, can you reproduce the problem with the new testcase? We didn't
handle DW_FORM_ref_addr properly. DW_FORM_ref_addr should be the
offset from the .debug_info section in the target file. This patch
fixes the testcase. But I don't know how to handle DW_FORM_ref_addr
references an entry in a different file.


H.J.
--
2006-09-29  H.J. Lu  <hongjiu.lu@intel.com>

	PR ld/3191
	* dwarf2.c (find_abstract_instance_name): Pass a pointer to
	attribute instead of offset.  For DW_FORM_ref_addr, get the
	entry at the offset from the .debug_info section.
	(scan_unit_for_symbols): Updated.
	(_bfd_dwarf2_find_nearest_line): Adjust debug_info
	section vma when needed.

--- bfd/dwarf2.c.ref_addr	2006-09-21 13:55:25.000000000 -0700
+++ bfd/dwarf2.c	2006-09-29 10:07:14.000000000 -0700
@@ -1556,16 +1556,30 @@ lookup_symbol_in_variable_table (struct 
 }
 
 static char *
-find_abstract_instance_name (struct comp_unit *unit, bfd_uint64_t die_ref)
+find_abstract_instance_name (struct comp_unit *unit,
+			     struct attribute *attr_ptr)
 {
   bfd *abfd = unit->abfd;
   bfd_byte *info_ptr;
   unsigned int abbrev_number, bytes_read, i;
   struct abbrev_info *abbrev;
+  bfd_uint64_t die_ref = attr_ptr->u.val;
   struct attribute attr;
   char *name = 0;
 
-  info_ptr = unit->info_ptr_unit + die_ref;
+  /* DW_FORM_ref_addr can reference an entry in a different CU. It
+     is an offset from the .debug_info section, not the current CU.  */
+  if (attr_ptr->form == DW_FORM_ref_addr)
+    {
+      /* FIXME: How to handle DW_FORM_ref_addr references an entry in
+	 a different file?  */ 
+      if (!die_ref)
+	abort ();
+
+      info_ptr = unit->stash->sec_info_ptr + die_ref;
+    }
+  else 
+    info_ptr = unit->info_ptr_unit + die_ref;
   abbrev_number = read_unsigned_leb128 (abfd, info_ptr, &bytes_read);
   info_ptr += bytes_read;
 
@@ -1591,7 +1605,7 @@ find_abstract_instance_name (struct comp
 		    name = attr.u.str;
 		  break;
 		case DW_AT_specification:
-		  name = find_abstract_instance_name (unit, attr.u.val);
+		  name = find_abstract_instance_name (unit, &attr);
 		  break;
 		case DW_AT_MIPS_linkage_name:
 		  name = attr.u.str;
@@ -1751,7 +1765,7 @@ scan_unit_for_symbols (struct comp_unit 
 		  break;
 
 		case DW_AT_abstract_origin:
-		  func->name = find_abstract_instance_name (unit, attr.u.val);
+		  func->name = find_abstract_instance_name (unit, &attr);
 		  break;
 
 		case DW_AT_name:
@@ -2375,6 +2389,11 @@ _bfd_dwarf2_find_nearest_line (bfd *abfd
     {
       bfd_size_type total_size;
       asection *msec;
+      bfd_vma last_vma;
+      bfd_size_type size;
+      asection *first_msec;
+      asection **msecs = NULL;
+      unsigned int i, count;
 
       *pinfo = stash;
 
@@ -2389,9 +2408,28 @@ _bfd_dwarf2_find_nearest_line (bfd *abfd
 	 Read them all in and produce one large stash.  We do this in two
 	 passes - in the first pass we just accumulate the section sizes.
 	 In the second pass we read in the section's contents.  The allows
-	 us to avoid reallocing the data as we add sections to the stash.  */
+	 us to avoid reallocing the data as we add sections to the stash.
+       
+	 We may need to adjust debug_info section vmas since we will
+	 concatenate them together.  Otherwise relocations may be
+	 incorrect.  */
+      first_msec = msec;
+      last_vma = 0;
+      count = 0;
       for (total_size = 0; msec; msec = find_debug_info (abfd, msec))
-	total_size += msec->size;
+	{
+	  size = msec->size;
+	  if (size == 0)
+	    continue;
+
+	  total_size += size;
+
+	  BFD_ASSERT (msec->vma == 0 && msec->alignment_power == 0);
+
+	  msec->vma = last_vma;
+	  last_vma += size;
+	  count++;
+	}
 
       stash->info_ptr = bfd_alloc (abfd, total_size);
       if (stash->info_ptr == NULL)
@@ -2399,17 +2437,27 @@ _bfd_dwarf2_find_nearest_line (bfd *abfd
 
       stash->info_ptr_end = stash->info_ptr;
 
-      for (msec = find_debug_info (abfd, NULL);
+      if (count > 1)
+	{
+	  count--;
+	  msecs = (asection **) bfd_malloc2 (count, sizeof (*msecs));
+	}
+
+      for (i = 0, msec = first_msec;
 	   msec;
 	   msec = find_debug_info (abfd, msec))
 	{
-	  bfd_size_type size;
 	  bfd_size_type start;
 
 	  size = msec->size;
 	  if (size == 0)
 	    continue;
 
+	  if (i && msecs)
+	    msecs [i - 1] = msec;
+
+	  i++;
+
 	  start = stash->info_ptr_end - stash->info_ptr;
 
 	  if ((bfd_simple_get_relocated_section_contents
@@ -2419,9 +2467,27 @@ _bfd_dwarf2_find_nearest_line (bfd *abfd
 	  stash->info_ptr_end = stash->info_ptr + start + size;
 	}
 
+      /* Restore section vma. */
+      if (count)
+	{
+	  if (msecs)
+	    {
+	      for (i = 0; i < count; i++)
+		msecs [i]->vma = 0;
+	      free (msecs);
+	    }
+	  else
+	    {
+	      for (msec = find_debug_info (abfd, first_msec);
+		   msec;
+		   msec = find_debug_info (abfd, msec))
+		msec->vma = 0;
+	    }
+	}
+
       BFD_ASSERT (stash->info_ptr_end == stash->info_ptr + total_size);
 
-      stash->sec = find_debug_info (abfd, NULL);
+      stash->sec = first_msec;
       stash->sec_info_ptr = stash->info_ptr;
       stash->syms = symbols;
     }