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optimize Xtensa relaxation
- From: Bob Wilson <bwilson at tensilica dot com>
- To: binutils at sources dot redhat dot com
- Date: Fri, 05 Oct 2007 12:05:08 -0700
- Subject: optimize Xtensa relaxation
OK, having gotten some smaller cleanups committed, I'm moving on to something of
more substance (though still not the problem I set out to solve)....
This patch reduces the Xtensa port's use of "fix" record to handle linker
relaxations that result in cross-object references. We were just being lazy and
using the fix records all the time, regardless of whether the reference was to
another object or even whether it had changed at all.
I tested this with the ld testsuite and also by building and running a few
larger programs. Committed on trunk.
2007-10-05 Bob Wilson <bob.wilson@acm.org>
* elf32-xtensa.c (relax_section): Call pin_internal_relocs when
changing a relocation's offset. Adjust call to translate_reloc. Do
not add a fix record for a DIFF reloc. For other relocs, only add a
fix record if the translated target is in a different object file;
otherwise, just update the relocation. Call pin_internal_relocs when
updating a reloc but not when adding a fix record.
(translate_reloc): Get the target section from a new argument, not
from the relocation. Change check for relaxable sections to an
assertion. Compute separate offset adjustments for the base symbol
and the addend, and set the new relocation's addend correctly. Return
the new target section.
Index: elf32-xtensa.c
===================================================================
RCS file: /cvs/src/src/bfd/elf32-xtensa.c,v
retrieving revision 1.98
diff -u -p -r1.98 elf32-xtensa.c
--- elf32-xtensa.c 5 Oct 2007 18:18:23 -0000 1.98
+++ elf32-xtensa.c 5 Oct 2007 18:28:37 -0000
@@ -5848,7 +5848,7 @@ static bfd_boolean move_shared_literal
static bfd_boolean relax_section (bfd *, asection *, struct bfd_link_info *);
static bfd_boolean translate_section_fixes (asection *);
static bfd_boolean translate_reloc_bfd_fix (reloc_bfd_fix *);
-static void translate_reloc (const r_reloc *, r_reloc *);
+static asection *translate_reloc (const r_reloc *, r_reloc *, asection *);
static void shrink_dynamic_reloc_sections
(struct bfd_link_info *, bfd *, asection *, Elf_Internal_Rela *);
static bfd_boolean move_literal
@@ -8094,6 +8094,8 @@ relax_section (bfd *abfd, asection *sec,
if (relax_info->is_relaxable_literal_section
|| relax_info->is_relaxable_asm_section)
{
+ pin_internal_relocs (sec, internal_relocs);
+
if (r_type != R_XTENSA_NONE
&& find_removed_literal (&relax_info->removed_list,
irel->r_offset))
@@ -8104,7 +8106,6 @@ relax_section (bfd *abfd, asection *sec,
irel->r_info = ELF32_R_INFO (0, R_XTENSA_NONE);
irel->r_offset = offset_with_removed_text
(&relax_info->action_list, irel->r_offset);
- pin_internal_relocs (sec, internal_relocs);
continue;
}
@@ -8156,10 +8157,7 @@ relax_section (bfd *abfd, asection *sec,
|| target_relax_info->is_relaxable_asm_section))
{
r_reloc new_reloc;
- reloc_bfd_fix *fix;
- bfd_vma addend_displacement;
-
- translate_reloc (&r_rel, &new_reloc);
+ target_sec = translate_reloc (&r_rel, &new_reloc, target_sec);
if (r_type == R_XTENSA_DIFF8
|| r_type == R_XTENSA_DIFF16
@@ -8226,21 +8224,32 @@ relax_section (bfd *abfd, asection *sec,
pin_contents (sec, contents);
}
+ else
+ {
+ /* If the relocation still references a section in the same
+ input file, modify the relocation directly instead of
+ adding a "fix" record. */
+ if (target_sec->owner == abfd)
+ {
+ unsigned r_symndx = ELF32_R_SYM (new_reloc.rela.r_info);
+ irel->r_info = ELF32_R_INFO (r_symndx, r_type);
+ irel->r_addend = new_reloc.rela.r_addend;
+ pin_internal_relocs (sec, internal_relocs);
+ }
+ else
+ {
+ bfd_vma addend_displacement;
+ reloc_bfd_fix *fix;
- /* FIXME: If the relocation still references a section in
- the same input file, the relocation should be modified
- directly instead of adding a "fix" record. */
-
- addend_displacement =
- new_reloc.target_offset + new_reloc.virtual_offset;
-
- fix = reloc_bfd_fix_init (sec, source_offset, r_type,
- r_reloc_get_section (&new_reloc),
- addend_displacement, TRUE);
- add_fix (sec, fix);
+ addend_displacement =
+ new_reloc.target_offset + new_reloc.virtual_offset;
+ fix = reloc_bfd_fix_init (sec, source_offset, r_type,
+ target_sec,
+ addend_displacement, TRUE);
+ add_fix (sec, fix);
+ }
+ }
}
-
- pin_internal_relocs (sec, internal_relocs);
}
}
@@ -8573,26 +8582,22 @@ translate_reloc_bfd_fix (reloc_bfd_fix *
/* Fix up a relocation to take account of removed literals. */
-static void
-translate_reloc (const r_reloc *orig_rel, r_reloc *new_rel)
+static asection *
+translate_reloc (const r_reloc *orig_rel, r_reloc *new_rel, asection *sec)
{
- asection *sec;
xtensa_relax_info *relax_info;
removed_literal *removed;
- bfd_vma new_offset, target_offset, removed_bytes;
+ bfd_vma target_offset, base_offset;
+ text_action *act;
*new_rel = *orig_rel;
if (!r_reloc_is_defined (orig_rel))
- return;
- sec = r_reloc_get_section (orig_rel);
+ return sec ;
relax_info = get_xtensa_relax_info (sec);
- BFD_ASSERT (relax_info);
-
- if (!relax_info->is_relaxable_literal_section
- && !relax_info->is_relaxable_asm_section)
- return;
+ BFD_ASSERT (relax_info && (relax_info->is_relaxable_literal_section
+ || relax_info->is_relaxable_asm_section));
target_offset = orig_rel->target_offset;
@@ -8623,19 +8628,37 @@ translate_reloc (const r_reloc *orig_rel
if (!relax_info
|| (!relax_info->is_relaxable_literal_section
&& !relax_info->is_relaxable_asm_section))
- return;
+ return sec;
}
target_offset = new_rel->target_offset;
}
- /* ...and the target address may have been moved within its section. */
- new_offset = offset_with_removed_text (&relax_info->action_list,
- target_offset);
+ /* Find the base offset of the reloc symbol, excluding any addend from the
+ reloc or from the section contents (for a partial_inplace reloc). Then
+ find the adjusted values of the offsets due to relaxation. The base
+ offset is needed to determine the change to the reloc's addend; the reloc
+ addend should not be adjusted due to relaxations located before the base
+ offset. */
+
+ base_offset = r_reloc_get_target_offset (new_rel) - new_rel->rela.r_addend;
+ act = relax_info->action_list.head;
+ if (base_offset <= target_offset)
+ {
+ int base_removed = removed_by_actions (&act, base_offset, FALSE);
+ int addend_removed = removed_by_actions (&act, target_offset, FALSE);
+ new_rel->target_offset = target_offset - base_removed - addend_removed;
+ new_rel->rela.r_addend -= addend_removed;
+ }
+ else
+ {
+ /* Handle a negative addend. The base offset comes first. */
+ int tgt_removed = removed_by_actions (&act, target_offset, FALSE);
+ int addend_removed = removed_by_actions (&act, base_offset, FALSE);
+ new_rel->target_offset = target_offset - tgt_removed;
+ new_rel->rela.r_addend += addend_removed;
+ }
- /* Modify the offset and addend. */
- removed_bytes = target_offset - new_offset;
- new_rel->target_offset = new_offset;
- new_rel->rela.r_addend -= removed_bytes;
+ return sec;
}