ld: Sort section contributions in PDB files

Microsoft's DIA library, and thus also MSVC and WinDbg, expects section
contributions to be ordered by section number and offset, otherwise it's
unable to resolve line numbers.

1 files changed, 63 insertions, 19 deletions

diff --git a/ld/pdb.c b/ld/pdb.c
index 12c4ac4..5e85f99 100644
--- a/ld/pdb.c
+++ b/ld/pdb.c
@@ -107,6 +107,13 @@ struct globals
   htab_t hashmap;
 };
 
+struct in_sc
+{
+  asection *s;
+  uint16_t sect_num;
+  uint16_t mod_index;
+};
+
 static const uint32_t crc_table[] =
 {
   0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
@@ -4118,6 +4125,27 @@ find_section_number (bfd *abfd, asection *sect)
   return 0;
 }
 
+/* Used as parameter to qsort, to sort section contributions by section and
+   offset.  */
+static int
+section_contribs_compare (const void *p1, const void *p2)
+{
+  const struct in_sc *sc1 = p1;
+  const struct in_sc *sc2 = p2;
+
+  if (sc1->sect_num < sc2->sect_num)
+    return -1;
+  if (sc1->sect_num > sc2->sect_num)
+    return 1;
+
+  if (sc1->s->output_offset < sc2->s->output_offset)
+    return -1;
+  if (sc1->s->output_offset > sc2->s->output_offset)
+    return 1;
+
+  return 0;
+}
+
 /* Create the substream which maps addresses in the image file to locations
    in the original object files.  */
 static bool
@@ -4128,6 +4156,8 @@ create_section_contrib_substream (bfd *abfd, void **data, uint32_t *size)
   uint16_t mod_index;
   char *sect_flags;
   file_ptr offset;
+  struct in_sc *sc_in, *sc2;
+  uint32_t *ptr;
 
   for (bfd *in = coff_data (abfd)->link_info->input_bfds; in;
        in = in->link.next)
@@ -4168,8 +4198,11 @@ create_section_contrib_substream (bfd *abfd, void **data, uint32_t *size)
       offset += sizeof (struct external_scnhdr);
     }
 
-  sc =
-    (struct section_contribution *) ((uint8_t *) *data + sizeof (uint32_t));
+  /* Microsoft's DIA expects section contributions to be sorted by section
+     number and offset, otherwise it will be unable to resolve line numbers.  */
+
+  sc_in = xmalloc (num_sc * sizeof (* sc_in));
+  sc2 = sc_in;
 
   mod_index = 0;
   for (bfd *in = coff_data (abfd)->link_info->input_bfds; in;
@@ -4177,32 +4210,43 @@ create_section_contrib_substream (bfd *abfd, void **data, uint32_t *size)
     {
       for (asection *s = in->sections; s; s = s->next)
 	{
-	  uint16_t sect_num;
-
 	  if (s->size == 0 || discarded_section (s))
 	    continue;
 
-	  sect_num = find_section_number (abfd, s->output_section);
-
-	  memcpy (&sc->characteristics,
-		  sect_flags + ((sect_num - 1) * sizeof (uint32_t)),
-		  sizeof (uint32_t));
-
-	  bfd_putl16 (sect_num, &sc->section);
-	  bfd_putl16 (0, &sc->padding1);
-	  bfd_putl32 (s->output_offset, &sc->offset);
-	  bfd_putl32 (s->size, &sc->size);
-	  bfd_putl16 (mod_index, &sc->module_index);
-	  bfd_putl16 (0, &sc->padding2);
-	  bfd_putl32 (0, &sc->data_crc);
-	  bfd_putl32 (0, &sc->reloc_crc);
+	  sc2->s = s;
+	  sc2->sect_num = find_section_number (abfd, s->output_section);
+	  sc2->mod_index = mod_index;
 
-	  sc++;
+	  sc2++;
 	}
 
       mod_index++;
     }
 
+  qsort (sc_in, num_sc, sizeof (* sc_in), section_contribs_compare);
+
+  ptr = *data;
+  sc = (struct section_contribution *) (ptr + 1); /* Skip the version word.  */
+
+  for (unsigned int i = 0; i < num_sc; i++)
+    {
+      memcpy (&sc->characteristics,
+	      sect_flags + ((sc_in[i].sect_num - 1) * sizeof (uint32_t)),
+	      sizeof (uint32_t));
+
+      bfd_putl16 (sc_in[i].sect_num, &sc->section);
+      bfd_putl16 (0, &sc->padding1);
+      bfd_putl32 (sc_in[i].s->output_offset, &sc->offset);
+      bfd_putl32 (sc_in[i].s->size, &sc->size);
+      bfd_putl16 (sc_in[i].mod_index, &sc->module_index);
+      bfd_putl16 (0, &sc->padding2);
+      bfd_putl32 (0, &sc->data_crc);
+      bfd_putl32 (0, &sc->reloc_crc);
+
+      sc++;
+    }
+
+  free (sc_in);
   free (sect_flags);
 
   return true;