Optimise PowerPC64 r2 adjusting stubs

Sometimes these stubs don't need to change the low 16-bits of r2, so in
that case omit a useless addi r2,r2,0 insn.  Also, change the get_r2off
error return from 0 to -1 since 0 is a valid return for ELFv2 -R objects.

	* elf64-ppc.c (get_r2off): Return -1 on error.
	(ppc_build_one_stub): Adjust for get_r2off change.  Don't emit
	addi r2,r2,0 on r2off stubs when the low 16-bit delta is zero.
	(ppc_size_one_stub): Corresponding size changes for r2off stubs.
	Add condition in test for -R objects.

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 58d2359b8d246380935a2a4d458c11c9dee16a58..5742aa3bf3a0be0bad40c7bee8544a3ef38c0998 100644 (file)
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,11 @@
+2015-08-31  Alan Modra  <amodra@gmail.com>
+
+       * elf64-ppc.c (get_r2off): Return -1 on error.
+       (ppc_build_one_stub): Adjust for get_r2off change.  Don't emit
+       addi r2,r2,0 on r2off stubs when the low 16-bit delta is zero.
+       (ppc_size_one_stub): Corresponding size changes for r2off stubs.
+       Add condition in test for -R objects.
+
 2015-08-31  Alan Modra  <amodra@gmail.com>
 
        * section.c (section_id): Make file scope.

diff --git a/bfd/elf64-ppc.c b/bfd/elf64-ppc.c
index efa124e43b00847061b10dfd811272ae5d1433d1..810b227b41a42ce085dce56e6b8eb5ecb76e1cb2 100644 (file)
--- a/bfd/elf64-ppc.c
+++ b/bfd/elf64-ppc.c
@@ -10540,10 +10540,10 @@ get_r2off (struct bfd_link_info *info,
          info->callbacks->einfo (_("%P: cannot find opd entry toc for `%T'\n"),
                                  stub_entry->h->elf.root.root.string);
          bfd_set_error (bfd_error_bad_value);
-         return 0;
+         return (bfd_vma) -1;
        }
       if (!bfd_get_section_contents (opd->owner, opd, buf, opd_off + 8, 8))
-       return 0;
+       return (bfd_vma) -1;
       r2off = bfd_get_64 (opd->owner, buf);
       r2off -= elf_gp (info->output_bfd);
     }
@@ -10599,23 +10599,28 @@ ppc_build_one_stub (struct bfd_hash_entry *gen_entry, void *in_arg)
        {
          bfd_vma r2off = get_r2off (info, stub_entry);
 
-         if (r2off == 0)
+         if (r2off == (bfd_vma) -1)
            {
              htab->stub_error = TRUE;
              return FALSE;
            }
          bfd_put_32 (htab->params->stub_bfd, STD_R2_0R1 + STK_TOC (htab), loc);
          loc += 4;
-         size = 12;
+         size = 8;
          if (PPC_HA (r2off) != 0)
            {
-             size = 16;
              bfd_put_32 (htab->params->stub_bfd,
                          ADDIS_R2_R2 | PPC_HA (r2off), loc);
              loc += 4;
+             size += 4;
+           }
+         if (PPC_LO (r2off) != 0)
+           {
+             bfd_put_32 (htab->params->stub_bfd,
+                         ADDI_R2_R2 | PPC_LO (r2off), loc);
+             loc += 4;
+             size += 4;
            }
-         bfd_put_32 (htab->params->stub_bfd, ADDI_R2_R2 | PPC_LO (r2off), loc);
-         loc += 4;
          off -= size - 4;
        }
       bfd_put_32 (htab->params->stub_bfd, B_DOT | (off & 0x3fffffc), loc);
@@ -10796,7 +10801,7 @@ ppc_build_one_stub (struct bfd_hash_entry *gen_entry, void *in_arg)
        {
          bfd_vma r2off = get_r2off (info, stub_entry);
 
-         if (r2off == 0 && htab->opd_abi)
+         if (r2off == (bfd_vma) -1)
            {
              htab->stub_error = TRUE;
              return FALSE;
@@ -11062,14 +11067,16 @@ ppc_size_one_stub (struct bfd_hash_entry *gen_entry, void *in_arg)
       if (stub_entry->stub_type == ppc_stub_long_branch_r2off)
        {
          r2off = get_r2off (info, stub_entry);
-         if (r2off == 0 && htab->opd_abi)
+         if (r2off == (bfd_vma) -1)
            {
              htab->stub_error = TRUE;
              return FALSE;
            }
-         size = 12;
+         size = 8;
          if (PPC_HA (r2off) != 0)
-           size = 16;
+           size += 4;
+         if (PPC_LO (r2off) != 0)
+           size += 4;
          off -= size - 4;
        }
 
@@ -11079,7 +11086,8 @@ ppc_size_one_stub (struct bfd_hash_entry *gen_entry, void *in_arg)
         Do the same for -R objects without function descriptors.  */
       if (off + (1 << 25) >= (bfd_vma) (1 << 26) - local_off
          || (stub_entry->stub_type == ppc_stub_long_branch_r2off
-             && r2off == 0))
+             && r2off == 0
+             && htab->sec_info[stub_entry->target_section->id].toc_off == 0))
        {
          struct ppc_branch_hash_entry *br_entry;