qsort: elf_sort_sections use of target_index

elf_sort_sections tried to ensure a stable qsort by using target_index
as the final comparison, but target_index hasn't been set by anything
at the time elf_sort_sections was run.  This patch arrange to have
target_index set.

	* elf.c (_bfd_elf_map_sections_to_segments): Init target_index
	for sections about to be sorted.
	(assign_file_positions_for_load_sections): Likewise.
	(elf_sort_sections): Don't bother optimising both TOEND case.
	* elflink.c (bfd_elf_final_link): Reset target_index.

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index e9c17584a46912bbc0bdd87e1a0ebbb6d1f34e46..6a5f673dea2f454aff707187a207962518a6f73e 100644 (file)
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,11 @@
+2019-10-14  Alan Modra  <amodra@gmail.com>
+
+       * elf.c (_bfd_elf_map_sections_to_segments): Init target_index
+       for sections about to be sorted.
+       (assign_file_positions_for_load_sections): Likewise.
+       (elf_sort_sections): Don't bother optimising both TOEND case.
+       * elflink.c (bfd_elf_final_link): Reset target_index.
+
 2019-10-14  Alan Modra  <amodra@gmail.com>
 
        * elflink.c (elf_get_linked_section_vma): Delete.

diff --git a/bfd/elf.c b/bfd/elf.c
index cbec4269cf0788431a6a0dc799bc92132673f5ce..314c866c3f10ba6e8e4b8ed8fd4ba66fbf83d7d2 100644 (file)
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -4703,6 +4703,10 @@ _bfd_elf_map_sections_to_segments (bfd *abfd, struct bfd_link_info *info)
        {
          if ((s->flags & SEC_ALLOC) != 0)
            {
+             /* target_index is unused until bfd_elf_final_link
+                starts output of section symbols.  Use it to make
+                qsort stable.  */
+             s->target_index = i;
              sections[i] = s;
              ++i;
              /* A wrapping section potentially clashes with header.  */
@@ -5270,14 +5274,7 @@ elf_sort_sections (const void *arg1, const void *arg2)
 
   if (TOEND (sec1))
     {
-      if (TOEND (sec2))
-       {
-         /* If the indices are the same, do not return 0
-            here, but continue to try the next comparison.  */
-         if (sec1->target_index - sec2->target_index != 0)
-           return sec1->target_index - sec2->target_index;
-       }
-      else
+      if (!TOEND (sec2))
        return 1;
     }
   else if (TOEND (sec2))
@@ -5479,8 +5476,12 @@ assign_file_positions_for_load_sections (bfd *abfd,
       if (m->count > 1
          && !(elf_elfheader (abfd)->e_type == ET_CORE
               && m->p_type == PT_NOTE))
-       qsort (m->sections, (size_t) m->count, sizeof (asection *),
-              elf_sort_sections);
+       {
+         for (i = 0; i < m->count; i++)
+           m->sections[i]->target_index = i;
+         qsort (m->sections, (size_t) m->count, sizeof (asection *),
+                elf_sort_sections);
+       }
 
       /* An ELF segment (described by Elf_Internal_Phdr) may contain a
         number of sections with contents contributing to both p_filesz

diff --git a/bfd/elflink.c b/bfd/elflink.c
index fedaf4b5a1f44efec32bf6be2d4591614caae66b..bfd0f019aad402b0743677d2e57a07aa1a9a0810 100644 (file)
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -12048,6 +12048,10 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
            goto error_return;
        }
 
+      /* _bfd_elf_compute_section_file_positions makes temporary use
+        of target_index.  Reset it.  */
+      o->target_index = 0;
+
       /* Now, reset REL_COUNT and REL_COUNT2 so that we can use them
         to count upwards while actually outputting the relocations.  */
       esdo->rel.count = 0;