From 44466e45c51b1c68ed2f95f86bcdb1f18f08b380 Mon Sep 17 00:00:00 2001 From: Nick Clifton Date: Thu, 20 Aug 2020 10:19:47 +0100 Subject: [PATCH] Apply a workaround to mitigate a quadratic performance hit in the linker when writing out secondary reloc sections. PR 26406 * elf-bfd.h (struct bfd_elf_section_data): Add has_secondary_relocs field. * elf.c (_bfd_elf_copy_special_section_fields): Set the has_secondary_relocs field for sections which have associated secondary relocs. * elfcode.h (elf_write_relocs): Only call write_secondary_relocs on sections which have associated secondary relocs. --- bfd/ChangeLog | 11 +++++++++++ bfd/elf-bfd.h | 5 +++++ bfd/elf.c | 22 ++++++++++++++++------ bfd/elfcode.h | 3 ++- 4 files changed, 34 insertions(+), 7 deletions(-) diff --git a/bfd/ChangeLog b/bfd/ChangeLog index 4106b52a99..8c43a163fc 100644 --- a/bfd/ChangeLog +++ b/bfd/ChangeLog @@ -1,3 +1,14 @@ +2020-08-20 Nick Clifton + + PR 26406 + * elf-bfd.h (struct bfd_elf_section_data): Add + has_secondary_relocs field. + * elf.c (_bfd_elf_copy_special_section_fields): Set the + has_secondary_relocs field for sections which have associated + secondary relocs. + * elfcode.h (elf_write_relocs): Only call write_secondary_relocs + on sections which have associated secondary relocs. + 2020-08-15 Alan Modra * elf32-frv.c (elf32_frv_add_symbol_hook): Set SEC_SMALL_DATA on diff --git a/bfd/elf-bfd.h b/bfd/elf-bfd.h index cd352d2a8e..eebdf9ac73 100644 --- a/bfd/elf-bfd.h +++ b/bfd/elf-bfd.h @@ -1756,6 +1756,11 @@ struct bfd_elf_section_data /* Link from a text section to its .eh_frame_entry section. */ asection *eh_frame_entry; + /* TRUE if the section has secondary reloc sections associated with it. + FIXME: In the future it might be better to change this into a list + of secondary reloc sections, making lookup easier and faster. */ + bfd_boolean has_secondary_relocs; + /* A pointer used for various section optimizations. */ void *sec_info; }; diff --git a/bfd/elf.c b/bfd/elf.c index 54c7204341..ecd9217b34 100644 --- a/bfd/elf.c +++ b/bfd/elf.c @@ -12714,6 +12714,7 @@ _bfd_elf_copy_special_section_fields (const bfd * ibfd ATTRIBUTE_UNUSED, { asection * isec; asection * osec; + struct bfd_elf_section_data * esd; if (isection == NULL) return FALSE; @@ -12729,8 +12730,9 @@ _bfd_elf_copy_special_section_fields (const bfd * ibfd ATTRIBUTE_UNUSED, if (osec == NULL) return FALSE; - BFD_ASSERT (elf_section_data (osec)->sec_info == NULL); - elf_section_data (osec)->sec_info = elf_section_data (isec)->sec_info; + esd = elf_section_data (osec); + BFD_ASSERT (esd->sec_info == NULL); + esd->sec_info = elf_section_data (isec)->sec_info; osection->sh_type = SHT_RELA; osection->sh_link = elf_onesymtab (obfd); if (osection->sh_link == 0) @@ -12770,18 +12772,26 @@ _bfd_elf_copy_special_section_fields (const bfd * ibfd ATTRIBUTE_UNUSED, return FALSE; } - osection->sh_info = - elf_section_data (isection->bfd_section->output_section)->this_idx; - + esd = elf_section_data (isection->bfd_section->output_section); + BFD_ASSERT (esd != NULL); + osection->sh_info = esd->this_idx; + esd->has_secondary_relocs = TRUE; #if DEBUG_SECONDARY_RELOCS fprintf (stderr, "update header of %s, sh_link = %u, sh_info = %u\n", osec->name, osection->sh_link, osection->sh_info); + fprintf (stderr, "mark section %s as having secondary relocs\n", + bfd_section_name (isection->bfd_section->output_section)); #endif return TRUE; } -/* Write out a secondary reloc section. */ +/* Write out a secondary reloc section. + + FIXME: Currently this function can result in a serious performance penalty + for files with secondary relocs and lots of sections. The proper way to + fix this is for _bfd_elf_copy_special_section_fields() to chain secondary + relocs together and then to have this function just walk that chain. */ bfd_boolean _bfd_elf_write_secondary_reloc_section (bfd *abfd, asection *sec) diff --git a/bfd/elfcode.h b/bfd/elfcode.h index 84b08b57eb..2ed2f135c3 100644 --- a/bfd/elfcode.h +++ b/bfd/elfcode.h @@ -999,7 +999,8 @@ elf_write_relocs (bfd *abfd, asection *sec, void *data) (*swap_out) (abfd, &src_rela, dst_rela); } - if (!bed->write_secondary_relocs (abfd, sec)) + if (elf_section_data (sec)->has_secondary_relocs + && !bed->write_secondary_relocs (abfd, sec)) { *failedp = TRUE; return; -- 2.34.1