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mn10300 dynamic relocation clean up: remove dynamic PCREL32
- From: Alexandre Oliva <aoliva at redhat dot com>
- To: binutils at sources dot redhat dot com
- Date: 26 Jun 2004 23:58:51 -0300
- Subject: mn10300 dynamic relocation clean up: remove dynamic PCREL32
- Organization: Red Hat Global Engineering Services Compiler Team
We used to generate a very large number of dynamic R_MN10300_NONE
relocations while linking libc.so and ld.so in glibc. As it turns
out, this was because we had accounted for dynamic relocations to be
generated for PC-relative relocations that were never needed, but the
code to get rid of them didn't work for some reason I didn't get to
investigate. I figured R_MN10300_PCREL32 were never specified as
dynamic relocations in the shared-library ABI extension; I just
implemented them because it looked easy enough and it sounded like a
good idea. I no longer think it is: it just makes it easier to create
libraries with TEXTREL relocations if you happen to compile code with
calls without @PLT annotations. I tried building glibc after removing
support for this dynamic relocation, and glibc shared libraries still
linked. So I went ahead and made sure non-dynamic relocs never
referenced symbols that didn't bind locally, and still no problems,
which is great. This patch is the result of the changes. I'm
checking it in.
Index: bfd/ChangeLog
from Alexandre Oliva <aoliva@redhat.com>
* elf-m10300.c (struct elf_mn10300_pcrel_relocs_copied): Delete.
(struct elf32_mn10300_link_hash_entry): Remove
pcrel_relocs_copied.
(mn10300_elf_check_relocs): Only reserve dynamic relocations for
R_MN10300_32. Don't adjust pcrel_relocs_copied.
(mn10300_elf_final_link_relocate): Fail for direct, pc-relative
and gotoff relocations if the symbol doesn't bind locally. Use
_bfd_elf_symbol_refs_local_p to test. Don't create dynamic
relocation for PCREL32.
(mn10300_elf_relocate_section): Use _bfd_elf_symbol_refs_local_p
to test whether a symbol binds locally.
(elf32_mn10300_link_hash_newfunc): Don't initialize
pcrel_relocs_copied.
(_bfd_mn10300_elf_discard_copies): Delete.
(_bfd_mn10300_elf_size_dynamic_sections): Don't call it.
Index: bfd/elf-m10300.c
===================================================================
RCS file: /cvs/src/src/bfd/elf-m10300.c,v
retrieving revision 1.54
diff -u -p -r1.54 elf-m10300.c
--- bfd/elf-m10300.c 24 Jun 2004 04:46:18 -0000 1.54
+++ bfd/elf-m10300.c 27 Jun 2004 02:49:41 -0000
@@ -52,19 +52,6 @@ bfd_boolean _bfd_mn10300_elf_merge_priva
linking with -Bsymbolic. We store the information in a field
extending the regular ELF linker hash table. */
-/* This structure keeps track of the number of PC relative relocs we
- have copied for a given symbol. */
-
-struct elf_mn10300_pcrel_relocs_copied
-{
- /* Next section. */
- struct elf_mn10300_pcrel_relocs_copied * next;
- /* A section in dynobj. */
- asection * section;
- /* Number of relocs copied in this section. */
- bfd_size_type count;
-};
-
struct elf32_mn10300_link_hash_entry {
/* The basic elf link hash table entry. */
struct elf_link_hash_entry root;
@@ -90,9 +77,6 @@ struct elf32_mn10300_link_hash_entry {
add it to the hash table to avoid computing it over and over. */
unsigned char movm_stack_size;
- /* Number of PC relative relocs copied for this symbol. */
- struct elf_mn10300_pcrel_relocs_copied * pcrel_relocs_copied;
-
/* When set, convert all "call" instructions to this target into "calls"
instructions. */
#define MN10300_CONVERT_CALL_TO_CALLS 0x1
@@ -166,9 +150,6 @@ static bfd_boolean _bfd_mn10300_elf_crea
PARAMS ((bfd *, struct bfd_link_info *));
static bfd_boolean _bfd_mn10300_elf_adjust_dynamic_symbol
PARAMS ((struct bfd_link_info *, struct elf_link_hash_entry *));
-static bfd_boolean _bfd_mn10300_elf_discard_copies
- PARAMS ((struct elf32_mn10300_link_hash_entry *,
- struct bfd_link_info *));
static bfd_boolean _bfd_mn10300_elf_size_dynamic_sections
PARAMS ((bfd *, struct bfd_link_info *));
static bfd_boolean _bfd_mn10300_elf_finish_dynamic_symbol
@@ -887,7 +868,6 @@ mn10300_elf_check_relocs (abfd, info, se
break;
- case R_MN10300_32:
case R_MN10300_24:
case R_MN10300_16:
case R_MN10300_8:
@@ -896,28 +876,16 @@ mn10300_elf_check_relocs (abfd, info, se
case R_MN10300_PCREL8:
if (h != NULL)
h->elf_link_hash_flags |= ELF_LINK_NON_GOT_REF;
+ break;
- /* If we are creating a shared library, and this is a reloc
- against a global symbol, or a non PC relative reloc
- against a local symbol, then we need to copy the reloc
- into the shared library. However, if we are linking with
- -Bsymbolic, we do not need to copy a reloc against a
- global symbol which is defined in an object we are
- including in the link (i.e., DEF_REGULAR is set). At
- this point we have not seen all the input files, so it is
- possible that DEF_REGULAR is not set now but will be set
- later (it is never cleared). We account for that
- possibility below by storing information in the
- pcrel_relocs_copied field of the hash table entry. */
+ case R_MN10300_32:
+ if (h != NULL)
+ h->elf_link_hash_flags |= ELF_LINK_NON_GOT_REF;
+
+ /* If we are creating a shared library, then we need to copy
+ the reloc into the shared library. */
if (info->shared
- && (sec->flags & SEC_ALLOC) != 0
- && (! (elf_mn10300_howto_table[ELF32_R_TYPE (rel->r_info)]
- .pc_relative)
- || (h != NULL
- && (! info->symbolic
- || h->root.type == bfd_link_hash_defweak
- || (h->elf_link_hash_flags
- & ELF_LINK_HASH_DEF_REGULAR) == 0))))
+ && (sec->flags & SEC_ALLOC) != 0)
{
/* When creating a shared object, we must copy these
reloc types into the output file. We create a reloc
@@ -955,43 +923,6 @@ mn10300_elf_check_relocs (abfd, info, se
}
sreloc->size += sizeof (Elf32_External_Rela);
-
- /* If we are linking with -Bsymbolic, and this is a
- global symbol, we count the number of PC relative
- relocations we have entered for this symbol, so that
- we can discard them again if the symbol is later
- defined by a regular object. Note that this function
- is only called if we are using an elf_sh linker
- hash table, which means that h is really a pointer to
- an elf32_mn10300_link_hash_entry. */
- if (h != NULL
- && (elf_mn10300_howto_table[ELF32_R_TYPE (rel->r_info)]
- .pc_relative))
- {
- struct elf32_mn10300_link_hash_entry *eh;
- struct elf_mn10300_pcrel_relocs_copied *p;
-
- eh = (struct elf32_mn10300_link_hash_entry *) h;
-
- for (p = eh->pcrel_relocs_copied; p != NULL; p = p->next)
- if (p->section == sreloc)
- break;
-
- if (p == NULL)
- {
- p = ((struct elf_mn10300_pcrel_relocs_copied *)
- bfd_alloc (dynobj, sizeof *p));
- if (p == NULL)
- return FALSE;
-
- p->next = eh->pcrel_relocs_copied;
- eh->pcrel_relocs_copied = p;
- p->section = sreloc;
- p->count = 0;
- }
-
- ++p->count;
- }
}
break;
@@ -1077,6 +1008,24 @@ mn10300_elf_final_link_relocate (howto,
switch (r_type)
{
+ case R_MN10300_24:
+ case R_MN10300_16:
+ case R_MN10300_8:
+ case R_MN10300_PCREL8:
+ case R_MN10300_PCREL16:
+ case R_MN10300_PCREL32:
+ case R_MN10300_GOTOFF32:
+ case R_MN10300_GOTOFF24:
+ case R_MN10300_GOTOFF16:
+ if (info->shared
+ && (input_section->flags & SEC_ALLOC) != 0
+ && h != NULL
+ && ! _bfd_elf_symbol_refs_local_p (h, info, 1))
+ return bfd_reloc_dangerous;
+ }
+
+ switch (r_type)
+ {
case R_MN10300_NONE:
return bfd_reloc_ok;
@@ -1130,9 +1079,7 @@ mn10300_elf_final_link_relocate (howto,
/* h->dynindx may be -1 if this symbol was marked to
become local. */
if (h == NULL
- || ((info->symbolic || h->dynindx == -1)
- && (h->elf_link_hash_flags
- & ELF_LINK_HASH_DEF_REGULAR) != 0))
+ || _bfd_elf_symbol_refs_local_p (h, info, 1))
{
relocate = TRUE;
outrel.r_info = ELF32_R_INFO (0, R_MN10300_RELATIVE);
@@ -1217,68 +1164,6 @@ mn10300_elf_final_link_relocate (howto,
return bfd_reloc_ok;
case R_MN10300_PCREL32:
- if (info->shared
- && (input_section->flags & SEC_ALLOC) != 0
- && h != NULL
- && h->dynindx != -1
- && (! info->symbolic
- || (h->elf_link_hash_flags
- & ELF_LINK_HASH_DEF_REGULAR) == 0))
- {
- Elf_Internal_Rela outrel;
- bfd_boolean skip;
-
- /* When generating a shared object, these relocations
- are copied into the output file to be resolved at run
- time. */
-
- if (sreloc == NULL)
- {
- const char * name;
-
- name = (bfd_elf_string_from_elf_section
- (input_bfd,
- elf_elfheader (input_bfd)->e_shstrndx,
- elf_section_data (input_section)->rel_hdr.sh_name));
- if (name == NULL)
- return FALSE;
-
- BFD_ASSERT (strncmp (name, ".rela", 5) == 0
- && strcmp (bfd_get_section_name (input_bfd,
- input_section),
- name + 5) == 0);
-
- sreloc = bfd_get_section_by_name (dynobj, name);
- BFD_ASSERT (sreloc != NULL);
- }
-
- skip = FALSE;
- outrel.r_offset = _bfd_elf_section_offset (input_bfd, info,
- input_section, offset);
- if (outrel.r_offset == (bfd_vma) -1)
- skip = TRUE;
-
- outrel.r_offset += (input_section->output_section->vma
- + input_section->output_offset);
-
- if (skip)
- memset (&outrel, 0, sizeof outrel);
- else
- {
- BFD_ASSERT (h != NULL && h->dynindx != -1);
- outrel.r_info = ELF32_R_INFO (h->dynindx, R_MN10300_PCREL32);
- outrel.r_addend = addend;
- }
-
- bfd_elf32_swap_reloca_out (output_bfd, &outrel,
- (bfd_byte *) (((Elf32_External_Rela *)
- sreloc->contents)
- + sreloc->reloc_count));
- ++sreloc->reloc_count;
-
- return bfd_reloc_ok;
- }
-
value -= (input_section->output_section->vma
+ input_section->output_offset);
value -= offset;
@@ -1417,9 +1302,7 @@ mn10300_elf_final_link_relocate (howto,
BFD_ASSERT (off != (bfd_vma) -1);
if (! elf_hash_table (info)->dynamic_sections_created
- || (info->shared
- && (info->symbolic || h->dynindx == -1)
- && (h->elf_link_hash_flags & ELF_LINK_HASH_DEF_REGULAR)))
+ || _bfd_elf_symbol_refs_local_p (h, info, 1))
/* This is actually a static link, or it is a
-Bsymbolic link and the symbol is defined
locally, or the symbol was forced to be local
@@ -1578,16 +1461,9 @@ mn10300_elf_relocate_section (output_bfd
|| r_type == R_MN10300_GOT24
|| r_type == R_MN10300_GOT16)
&& elf_hash_table (info)->dynamic_sections_created
- && (! info->shared
- || (! info->symbolic && h->root.dynindx != -1)
- || (h->root.elf_link_hash_flags
- & ELF_LINK_HASH_DEF_REGULAR) == 0))
- || (info->shared
- && ((! info->symbolic && h->root.dynindx != -1)
- || (h->root.elf_link_hash_flags
- & ELF_LINK_HASH_DEF_REGULAR) == 0)
- && ( r_type == R_MN10300_32
- || r_type == R_MN10300_PCREL32)
+ && !_bfd_elf_symbol_refs_local_p (h, info, 1))
+ || (r_type == R_MN10300_32
+ && !_bfd_elf_symbol_refs_local_p (h, info, 1)
&& ((input_section->flags & SEC_ALLOC) != 0
/* DWARF will emit R_MN10300_32 relocations
in its sections against symbols defined
@@ -3816,7 +3692,6 @@ elf32_mn10300_link_hash_newfunc (entry,
ret->stack_size = 0;
ret->movm_args = 0;
ret->movm_stack_size = 0;
- ret->pcrel_relocs_copied = NULL;
ret->flags = 0;
}
@@ -4300,34 +4175,6 @@ _bfd_mn10300_elf_adjust_dynamic_symbol (
return TRUE;
}
-/* This function is called via elf32_mn10300_link_hash_traverse if we are
- creating a shared object with -Bsymbolic. It discards the space
- allocated to copy PC relative relocs against symbols which are
- defined in regular objects. We allocated space for them in the
- check_relocs routine, but we won't fill them in in the
- relocate_section routine. */
-
-static bfd_boolean
-_bfd_mn10300_elf_discard_copies (h, info)
- struct elf32_mn10300_link_hash_entry *h;
- struct bfd_link_info *info;
-{
- struct elf_mn10300_pcrel_relocs_copied *s;
-
- /* If a symbol has been forced local or we have found a regular
- definition for the symbolic link case, then we won't be needing
- any relocs. */
- if ((h->root.elf_link_hash_flags & ELF_LINK_HASH_DEF_REGULAR) != 0
- && ((h->root.elf_link_hash_flags & ELF_LINK_FORCED_LOCAL) != 0
- || info->symbolic))
- {
- for (s = h->pcrel_relocs_copied; s != NULL; s = s->next)
- s->section->size -= s->count * sizeof (Elf32_External_Rel);
- }
-
- return TRUE;
-}
-
/* Set the sizes of the dynamic sections. */
static bfd_boolean
@@ -4367,15 +4214,6 @@ _bfd_mn10300_elf_size_dynamic_sections (
s->size = 0;
}
- /* If this is a -Bsymbolic shared link, then we need to discard all
- PC relative relocs against symbols defined in a regular object.
- We allocated space for them in the check_relocs routine, but we
- will not fill them in in the relocate_section routine. */
- if (info->shared && info->symbolic)
- elf32_mn10300_link_hash_traverse (elf32_mn10300_hash_table (info),
- _bfd_mn10300_elf_discard_copies,
- info);
-
/* The check_relocs and adjust_dynamic_symbol entry points have
determined the sizes of the various dynamic sections. Allocate
memory for them. */
--
Alexandre Oliva http://www.ic.unicamp.br/~oliva/
Red Hat Compiler Engineer aoliva@{redhat.com, gcc.gnu.org}
Free Software Evangelist oliva@{lsd.ic.unicamp.br, gnu.org}