x86: Remove func_pointer_refcount
Since check_reloc is running after gc_sections, there is no need for reference count. If a function pointer relocation can be resolved at run-time, there is no need for PLT and it doesn't count as non-GOT/PLT relocation. func_pointer_refcount can be removed. * elf32-i386.c (elf_i386_check_relocs): Set plt.refcount to 1. Don't use func_pointer_refcount. Don't set plt.refcount nor non_got_ref for function pointer reference. * elf64-x86-64.c (elf_x86_64_check_relocs): Likewise. * elfxx-x86.c (elf_x86_allocate_dynrelocs): Don't use func_pointer_refcount. (_bfd_x86_elf_copy_indirect_symbol): Don't copy func_pointer_refcount. (_bfd_x86_elf_hide_symbol): Don't use func_pointer_refcount. * elfxx-x86.h (GENERATE_DYNAMIC_RELOCATION_P): Likewise. (elf_x86_link_hash_entry): Remove func_pointer_refcount.
This commit is contained in:
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79b0c981b8
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@ -1,3 +1,17 @@
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2017-11-03 H.J. Lu <hongjiu.lu@intel.com>
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* elf32-i386.c (elf_i386_check_relocs): Set plt.refcount to 1.
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Don't use func_pointer_refcount. Don't set plt.refcount nor
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non_got_ref for function pointer reference.
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* elf64-x86-64.c (elf_x86_64_check_relocs): Likewise.
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* elfxx-x86.c (elf_x86_allocate_dynrelocs): Don't use
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func_pointer_refcount.
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(_bfd_x86_elf_copy_indirect_symbol): Don't copy
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func_pointer_refcount.
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(_bfd_x86_elf_hide_symbol): Don't use func_pointer_refcount.
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* elfxx-x86.h (GENERATE_DYNAMIC_RELOCATION_P): Likewise.
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(elf_x86_link_hash_entry): Remove func_pointer_refcount.
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2017-11-03 Mingi Cho <mgcho.minic@gmail.com>
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Nick Clifton <nickc@redhat.com>
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@ -1600,7 +1600,7 @@ elf_i386_check_relocs (bfd *abfd,
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eh->zero_undefweak &= 0x2;
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h->needs_plt = 1;
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h->plt.refcount += 1;
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h->plt.refcount = 1;
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break;
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case R_386_SIZE32:
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@ -1751,20 +1751,7 @@ do_relocation:
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&& (bfd_link_executable (info)
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|| h->type == STT_GNU_IFUNC))
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{
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/* If this reloc is in a read-only section, we might
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need a copy reloc. We can't check reliably at this
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stage whether the section is read-only, as input
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sections have not yet been mapped to output sections.
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Tentatively set the flag for now, and correct in
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adjust_dynamic_symbol. */
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h->non_got_ref = 1;
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/* We may need a .plt entry if the symbol is a function
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defined in a shared lib or is a STT_GNU_IFUNC function
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referenced from the code or read-only section. */
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if (!h->def_regular
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|| (sec->flags & (SEC_CODE | SEC_READONLY)) != 0)
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h->plt.refcount += 1;
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bfd_boolean func_pointer_ref = FALSE;
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if (r_type == R_386_PC32)
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{
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@ -1790,7 +1777,25 @@ do_relocation:
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/* R_386_32 can be resolved at run-time. */
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if (r_type == R_386_32
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&& (sec->flags & SEC_READONLY) == 0)
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eh->func_pointer_refcount += 1;
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func_pointer_ref = TRUE;
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}
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if (!func_pointer_ref)
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{
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/* If this reloc is in a read-only section, we might
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need a copy reloc. We can't check reliably at this
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stage whether the section is read-only, as input
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sections have not yet been mapped to output sections.
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Tentatively set the flag for now, and correct in
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adjust_dynamic_symbol. */
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h->non_got_ref = 1;
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/* We may need a .plt entry if the symbol is a function
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defined in a shared lib or is a function referenced
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from the code or read-only section. */
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if (!h->def_regular
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|| (sec->flags & (SEC_CODE | SEC_READONLY)) != 0)
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h->plt.refcount = 1;
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}
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}
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@ -2067,7 +2067,7 @@ elf_x86_64_check_relocs (bfd *abfd, struct bfd_link_info *info,
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eh->zero_undefweak &= 0x2;
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h->needs_plt = 1;
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h->plt.refcount += 1;
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h->plt.refcount = 1;
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break;
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case R_X86_64_PLTOFF64:
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@ -2076,7 +2076,7 @@ elf_x86_64_check_relocs (bfd *abfd, struct bfd_link_info *info,
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if (h != NULL)
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{
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h->needs_plt = 1;
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h->plt.refcount += 1;
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h->plt.refcount = 1;
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}
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goto create_got;
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@ -2124,20 +2124,7 @@ pointer:
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&& (bfd_link_executable (info)
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|| h->type == STT_GNU_IFUNC))
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{
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/* If this reloc is in a read-only section, we might
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need a copy reloc. We can't check reliably at this
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stage whether the section is read-only, as input
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sections have not yet been mapped to output sections.
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Tentatively set the flag for now, and correct in
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adjust_dynamic_symbol. */
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h->non_got_ref = 1;
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/* We may need a .plt entry if the symbol is a function
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defined in a shared lib or is a STT_GNU_IFUNC function
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referenced from the code or read-only section. */
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if (!h->def_regular
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|| (sec->flags & (SEC_CODE | SEC_READONLY)) != 0)
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h->plt.refcount += 1;
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bfd_boolean func_pointer_ref = FALSE;
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if (r_type == R_X86_64_PC32)
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{
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@ -2159,7 +2146,25 @@ pointer:
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|| (!ABI_64_P (abfd)
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&& (r_type == R_X86_64_32
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|| r_type == R_X86_64_32S))))
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eh->func_pointer_refcount += 1;
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func_pointer_ref = TRUE;
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}
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if (!func_pointer_ref)
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{
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/* If this reloc is in a read-only section, we might
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need a copy reloc. We can't check reliably at this
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stage whether the section is read-only, as input
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sections have not yet been mapped to output sections.
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Tentatively set the flag for now, and correct in
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adjust_dynamic_symbol. */
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h->non_got_ref = 1;
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/* We may need a .plt entry if the symbol is a function
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defined in a shared lib or is a function referenced
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from the code or read-only section. */
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if (!h->def_regular
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|| (sec->flags & (SEC_CODE | SEC_READONLY)) != 0)
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h->plt.refcount = 1;
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}
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}
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@ -108,11 +108,6 @@ elf_x86_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
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resolved_to_zero = UNDEFINED_WEAK_RESOLVED_TO_ZERO (info, eh);
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/* Clear the reference count of function pointer relocations if
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symbol isn't a normal function. */
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if (h->type != STT_FUNC)
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eh->func_pointer_refcount = 0;
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/* We can't use the GOT PLT if pointer equality is needed since
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finish_dynamic_symbol won't clear symbol value and the dynamic
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linker won't update the GOT slot. We will get into an infinite
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@ -162,15 +157,11 @@ elf_x86_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
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/* Don't create the PLT entry if there are only function pointer
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relocations which can be resolved at run-time. */
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else if (htab->elf.dynamic_sections_created
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&& (h->plt.refcount > eh->func_pointer_refcount
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&& (h->plt.refcount > 0
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|| eh->plt_got.refcount > 0))
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{
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bfd_boolean use_plt_got = eh->plt_got.refcount > 0;
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/* Clear the reference count of function pointer relocations
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if PLT is used. */
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eh->func_pointer_refcount = 0;
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/* Make sure this symbol is output as a dynamic symbol.
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Undefined weak syms won't yet be marked as dynamic. */
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if (h->dynindx == -1
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@ -488,7 +479,6 @@ elf_x86_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
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pointer initialization. */
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if ((!h->non_got_ref
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|| eh->func_pointer_refcount > 0
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|| (h->root.type == bfd_link_hash_undefweak
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&& !resolved_to_zero))
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&& ((h->def_dynamic
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@ -513,7 +503,6 @@ elf_x86_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
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}
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eh->dyn_relocs = NULL;
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eh->func_pointer_refcount = 0;
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keep: ;
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}
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@ -1643,15 +1632,7 @@ _bfd_x86_elf_copy_indirect_symbol (struct bfd_link_info *info,
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dir->pointer_equality_needed |= ind->pointer_equality_needed;
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}
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else
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{
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if (eind->func_pointer_refcount > 0)
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{
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edir->func_pointer_refcount += eind->func_pointer_refcount;
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eind->func_pointer_refcount = 0;
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}
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_bfd_elf_link_hash_copy_indirect (info, dir, ind);
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}
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_bfd_elf_link_hash_copy_indirect (info, dir, ind);
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}
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/* Remove undefined weak symbol from the dynamic symbol table if it
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weak symbol dynamic so that PC relative branch to the undefined
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weak symbol will land to address 0. */
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struct elf_x86_link_hash_entry *eh = elf_x86_hash_entry (h);
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if (h->plt.refcount > eh->func_pointer_refcount
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if (h->plt.refcount > 0
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|| eh->plt_got.refcount > 0)
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return;
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}
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@ -133,7 +133,6 @@
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&& (EH) != NULL \
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&& (EH)->elf.dynindx != -1 \
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&& (!(EH)->elf.non_got_ref \
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|| (EH)->func_pointer_refcount > 0 \
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|| ((EH)->elf.root.type == bfd_link_hash_undefweak \
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&& !(RESOLVED_TO_ZERO))) \
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&& (((EH)->elf.def_dynamic && !(EH)->elf.def_regular) \
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@ -268,10 +267,6 @@ struct elf_x86_link_hash_entry
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is only used by x86-64. */
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unsigned int needs_copy : 1;
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/* Reference count of C/C++ function pointer relocations in read-write
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section which can be resolved at run-time. */
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bfd_signed_vma func_pointer_refcount;
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/* Information about the GOT PLT entry. Filled when there are both
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GOT and PLT relocations against the same function. */
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union gotplt_union plt_got;
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