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[ARC] Add linker relaxation.
Add linker relaxation. The first relaxation added is converting GOTPC32 to PCREL relocations. This relaxation doesn't change the size of the binary. bfd/ xxxx-xx-xx Claudiu Zissulescu <claziss@synopsys.com> * elf32-arc.c (bfd_get_32_me): New function. (bfd_put_32_me): Likewise. (arc_elf_relax_section): Likewise. (bfd_elf32_bfd_relax_section): Define. ld/testsuite/ xxxx-xx-xx Claudiu Zissulescu <claziss@synopsys.com> * ld-arc/relax-local-pic.d: New test. * ld-arc/relax-local-pic.s: New file.
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Claudiu Zissulescu
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c54e42531a
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ef551643dc
@ -1,3 +1,10 @@
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2019-07-24 Claudiu Zissulescu <claziss@synopsys.com>
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* elf32-arc.c (bfd_get_32_me): New function.
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(bfd_put_32_me): Likewise.
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(arc_elf_relax_section): Likewise.
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(bfd_elf32_bfd_relax_section): Define.
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2019-07-24 Alan Modra <amodra@gmail.com>
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* elf-bfd.h (struct elf_backend_data): Return bfd_boolean from
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176
bfd/elf32-arc.c
176
bfd/elf32-arc.c
@ -96,6 +96,31 @@ reloc_type_to_name (unsigned int type)
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#define USE_REL 1
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static bfd_vma
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bfd_get_32_me (bfd * abfd,const unsigned char * data)
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{
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bfd_vma value = 0;
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if (bfd_big_endian(abfd)) {
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value = bfd_get_32 (abfd, data);
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}
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else {
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value = ((bfd_get_8 (abfd, data) & 255) << 16);
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value |= ((bfd_get_8 (abfd, data + 1) & 255) << 24);
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value |= (bfd_get_8 (abfd, data + 2) & 255);
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value |= ((bfd_get_8 (abfd, data + 3) & 255) << 8);
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}
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return value;
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}
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static void
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bfd_put_32_me (bfd *abfd, bfd_vma value,unsigned char *data)
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{
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bfd_put_16 (abfd, (value & 0xffff0000) >> 16, data);
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bfd_put_16 (abfd, value & 0xffff, data + 2);
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}
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static ATTRIBUTE_UNUSED bfd_boolean
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is_reloc_PC_relative (reloc_howto_type *howto)
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{
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@ -2968,6 +2993,156 @@ elf32_arc_section_from_shdr (bfd *abfd,
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return TRUE;
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}
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/* Relaxation hook.
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These are the current relaxing opportunities available:
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* R_ARC_GOTPC32 => R_ARC_PCREL.
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*/
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static bfd_boolean
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arc_elf_relax_section (bfd *abfd, asection *sec,
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struct bfd_link_info *link_info, bfd_boolean *again)
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{
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Elf_Internal_Shdr *symtab_hdr;
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Elf_Internal_Rela *internal_relocs;
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Elf_Internal_Rela *irel, *irelend;
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bfd_byte *contents = NULL;
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Elf_Internal_Sym *isymbuf = NULL;
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/* Assume nothing changes. */
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*again = FALSE;
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/* We don't have to do anything for a relocatable link, if this
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section does not have relocs, or if this is not a code
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section. */
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if (bfd_link_relocatable (link_info)
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|| (sec->flags & SEC_RELOC) == 0
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|| sec->reloc_count == 0
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|| (sec->flags & SEC_CODE) == 0)
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return TRUE;
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symtab_hdr = &elf_tdata (abfd)->symtab_hdr;
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/* Get a copy of the native relocations. */
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internal_relocs = _bfd_elf_link_read_relocs (abfd, sec, NULL, NULL,
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link_info->keep_memory);
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if (internal_relocs == NULL)
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goto error_return;
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/* Walk through them looking for relaxing opportunities. */
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irelend = internal_relocs + sec->reloc_count;
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for (irel = internal_relocs; irel < irelend; irel++)
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{
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/* If this isn't something that can be relaxed, then ignore
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this reloc. */
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if (ELF32_R_TYPE (irel->r_info) != (int) R_ARC_GOTPC32)
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continue;
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/* Get the section contents if we haven't done so already. */
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if (contents == NULL)
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{
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/* Get cached copy if it exists. */
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if (elf_section_data (sec)->this_hdr.contents != NULL)
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contents = elf_section_data (sec)->this_hdr.contents;
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/* Go get them off disk. */
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else if (!bfd_malloc_and_get_section (abfd, sec, &contents))
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goto error_return;
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}
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/* Read this BFD's local symbols if we haven't done so already. */
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if (isymbuf == NULL && symtab_hdr->sh_info != 0)
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{
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isymbuf = (Elf_Internal_Sym *) symtab_hdr->contents;
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if (isymbuf == NULL)
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isymbuf = bfd_elf_get_elf_syms (abfd, symtab_hdr,
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symtab_hdr->sh_info, 0,
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NULL, NULL, NULL);
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if (isymbuf == NULL)
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goto error_return;
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}
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struct elf_link_hash_entry *htop = NULL;
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if (ELF32_R_SYM (irel->r_info) >= symtab_hdr->sh_info)
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{
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/* An external symbol. */
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unsigned int indx = ELF32_R_SYM (irel->r_info) - symtab_hdr->sh_info;
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htop = elf_sym_hashes (abfd)[indx];
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}
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if (ELF32_R_TYPE (irel->r_info) == (int) R_ARC_GOTPC32
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&& SYMBOL_REFERENCES_LOCAL (link_info, htop))
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{
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unsigned int code;
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/* Get the opcode. */
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code = bfd_get_32_me (abfd, contents + irel->r_offset - 4);
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/* Note that we've changed the relocs, section contents, etc. */
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elf_section_data (sec)->relocs = internal_relocs;
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elf_section_data (sec)->this_hdr.contents = contents;
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symtab_hdr->contents = (unsigned char *) isymbuf;
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/* Fix the relocation's type. */
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irel->r_info = ELF32_R_INFO (ELF32_R_SYM (irel->r_info), R_ARC_PC32);
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/* ld rA,[pcl,symbol@tgot] -> add rA,pcl,symbol@pcl. */
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/* 0010 0bbb aa11 0ZZX DBBB 1111 10AA AAAA.
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111 00 000 0111 xx xxxx*/
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code &= ~0x27307F80;
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BFD_ASSERT (code <= 62UL);
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code |= 0x27007F80;
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/* Write back the new instruction. */
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bfd_put_32_me (abfd, code, contents + irel->r_offset - 4);
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/* The size isn't changed, don't redo. */
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*again = FALSE;
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}
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}
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if (isymbuf != NULL
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&& symtab_hdr->contents != (unsigned char *) isymbuf)
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{
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if (!link_info->keep_memory)
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free (isymbuf);
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else
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/* Cache the symbols for elf_link_input_bfd. */
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symtab_hdr->contents = (unsigned char *) isymbuf;
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}
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if (contents != NULL
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&& elf_section_data (sec)->this_hdr.contents != contents)
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{
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if (!link_info->keep_memory)
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free (contents);
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else
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/* Cache the section contents for elf_link_input_bfd. */
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elf_section_data (sec)->this_hdr.contents = contents;
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}
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if (internal_relocs != NULL
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&& elf_section_data (sec)->relocs != internal_relocs)
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free (internal_relocs);
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return TRUE;
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error_return:
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if (isymbuf != NULL
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&& symtab_hdr->contents != (unsigned char *) isymbuf)
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free (isymbuf);
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if (contents != NULL
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&& elf_section_data (sec)->this_hdr.contents != contents)
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free (contents);
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if (internal_relocs != NULL
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&& elf_section_data (sec)->relocs != internal_relocs)
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free (internal_relocs);
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return FALSE;
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}
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#define TARGET_LITTLE_SYM arc_elf32_le_vec
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#define TARGET_LITTLE_NAME "elf32-littlearc"
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#define TARGET_BIG_SYM arc_elf32_be_vec
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@ -2985,6 +3160,7 @@ elf32_arc_section_from_shdr (bfd *abfd,
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#define bfd_elf32_bfd_set_private_flags arc_elf_set_private_flags
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#define bfd_elf32_bfd_print_private_bfd_data arc_elf_print_private_bfd_data
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#define bfd_elf32_bfd_copy_private_bfd_data arc_elf_copy_private_bfd_data
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#define bfd_elf32_bfd_relax_section arc_elf_relax_section
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#define elf_info_to_howto_rel arc_info_to_howto_rel
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#define elf_backend_object_p arc_elf_object_p
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@ -1,3 +1,8 @@
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2019-07-24 Claudiu Zissulescu <claziss@synopsys.com>
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* ld-arc/relax-local-pic.d: New test.
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* ld-arc/relax-local-pic.s: New file.
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2019-07-22 Martin Liska <mliska@suse.cz>
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* testsuite/ld-plugin/lto-3r.d: Remove.
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14
ld/testsuite/ld-arc/relax-local-pic.d
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14
ld/testsuite/ld-arc/relax-local-pic.d
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@ -0,0 +1,14 @@
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#source: relax-local-pic.s
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#as:
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#ld: -q -A elf32-arclittle -relax
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#objdump: -dr
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[^:]+: file format elf32-.*arc
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Disassembly of section \.text:
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00000100 <__start>:
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100: 2700 7f84 0000 [0-9a-f]+ add r4,pcl,0x[0-9a-f]+.*
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104: R_ARC_PC32 a_in_other_thread
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108: 1c00 [0-9a-f\s]+ st\s+.*
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16
ld/testsuite/ld-arc/relax-local-pic.s
Normal file
16
ld/testsuite/ld-arc/relax-local-pic.s
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@ -0,0 +1,16 @@
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.section .text
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.align 4
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.global __start
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.type __start, @function
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__start:
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ld r4,[pcl,@a_in_other_thread@gotpc]
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st 1,[r4]
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.size __start, .-__start
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.global a_in_other_thread
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.section .data
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.align 4
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.type a_in_other_thread, @object
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.size a_in_other_thread, 4
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a_in_other_thread:
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.word -559038737
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