1 /* LTO plugin for gold.
2 Copyright (C) 2009 Free Software Foundation, Inc.
3 Contributed by Rafael Avila de Espindola (espindola@google.com).
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 3, or (at your option)
10 This program is distributed in the hope that it will be useful, but
11 WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program; see the file COPYING3. If not see
17 <http://www.gnu.org/licenses/>. */
19 /* The plugin has only one external function: onload. Gold passes it an array of
20 function that the plugin uses to communicate back to gold.
22 With the functions provided by gold, the plugin can be notified when
23 gold first analyzes a file and pass a symbol table back to gold. The plugin
24 is also notified when all symbols have been read and it is time to generate
25 machine code for the necessary symbols.
27 More information at http://gcc.gnu.org/wiki/whopr/driver.
29 This plugin should be passed the lto-wrapper options and will forward them.
30 It also has 2 options of its own:
31 -debug: Print the command line used to run lto-wrapper.
32 -nop: Instead of running lto-wrapper, pass the original to the plugin. This
33 only works if the input files are hybrid. */
43 #include <sys/types.h>
46 #include <libiberty.h>
48 /* The presence of gelf.h is checked by the toplevel configure script. */
51 #include "plugin-api.h"
52 #include "../gcc/lto/common.h"
54 /* The part of the symbol table the plugin has to keep track of. Note that we
55 must keep SYMS until all_symbols_read is called to give the linker time to
56 copy the symbol information. */
62 struct ld_plugin_symbol *syms;
65 /* All that we have to remember about a file. */
67 struct plugin_file_info
71 struct plugin_symtab symtab;
75 static char *arguments_file_name;
76 static ld_plugin_register_claim_file register_claim_file;
77 static ld_plugin_add_symbols add_symbols;
78 static ld_plugin_register_all_symbols_read register_all_symbols_read;
79 static ld_plugin_get_symbols get_symbols;
80 static ld_plugin_register_cleanup register_cleanup;
81 static ld_plugin_add_input_file add_input_file;
82 static ld_plugin_add_input_library add_input_library;
83 static ld_plugin_message message;
85 static struct plugin_file_info *claimed_files = NULL;
86 static unsigned int num_claimed_files = 0;
88 static char **output_files = NULL;
89 static unsigned int num_output_files = 0;
91 static char **lto_wrapper_argv;
92 static int lto_wrapper_num_args;
94 static char **pass_through_items = NULL;
95 static unsigned int num_pass_through_items;
99 static char *resolution_file = NULL;
102 check (bool gate, enum ld_plugin_level level, const char *text)
108 message (level, text);
111 /* If there is no nicer way to inform the user, fallback to stderr. */
112 fprintf (stderr, "%s\n", text);
113 if (level == LDPL_FATAL)
118 /* Parse an entry of the IL symbol table. The data to be parsed is pointed
119 by P and the result is written in ENTRY. The slot number is stored in SLOT.
120 Returns the address of the next entry. */
123 parse_table_entry (char *p, struct ld_plugin_symbol *entry, uint32_t *slot)
126 enum ld_plugin_symbol_kind translate_kind[] =
135 enum ld_plugin_symbol_visibility translate_visibility[] =
143 entry->name = xstrdup (p);
148 entry->version = NULL;
150 entry->comdat_key = p;
155 if (strlen (entry->comdat_key) == 0)
156 entry->comdat_key = NULL;
158 entry->comdat_key = xstrdup (entry->comdat_key);
161 check (t <= 4, LDPL_FATAL, "invalid symbol kind found");
162 entry->def = translate_kind[t];
166 check (t <= 3, LDPL_FATAL, "invalid symbol visibility found");
167 entry->visibility = translate_visibility[t];
170 entry->size = *(uint64_t *) p;
173 *slot = *(uint32_t *) p;
176 entry->resolution = LDPR_UNKNOWN;
181 /* Return the section in ELF that is named NAME. */
184 get_section (Elf *elf, const char *name)
186 Elf_Scn *section = 0;
188 GElf_Ehdr *t = gelf_getehdr (elf, &header);
191 assert (t == &header);
193 while ((section = elf_nextscn(elf, section)) != 0)
196 GElf_Shdr *tshdr = gelf_getshdr (section, &shdr);
198 assert (tshdr == &shdr);
199 t = elf_strptr (elf, header.e_shstrndx, shdr.sh_name);
201 if (strcmp (t, name) == 0)
207 /* Returns the IL symbol table of file ELF. */
210 get_symtab (Elf *elf)
213 Elf_Scn *section = get_section (elf, ".gnu.lto_.symtab");
217 data = elf_getdata (section, data);
222 /* Translate the IL symbol table SYMTAB. Write the slots and symbols in OUT. */
225 translate (Elf_Data *symtab, struct plugin_symtab *out)
227 uint32_t *slots = NULL;
228 char *data = symtab->d_buf;
229 char *end = data + symtab->d_size;
230 struct ld_plugin_symbol *syms = NULL;
236 syms = xrealloc (syms, n * sizeof (struct ld_plugin_symbol));
237 check (syms, LDPL_FATAL, "could not allocate memory");
238 slots = xrealloc (slots, n * sizeof (uint32_t));
239 check (slots, LDPL_FATAL, "could not allocate memory");
240 data = parse_table_entry (data, &syms[n - 1], &slots[n - 1]);
248 /* Free all memory that is no longer needed after writing the symbol
255 for (i = 0; i < num_claimed_files; i++)
257 struct plugin_file_info *info = &claimed_files[i];
258 struct plugin_symtab *symtab = &info->symtab;
260 for (j = 0; j < symtab->nsyms; j++)
262 struct ld_plugin_symbol *s = &symtab->syms[j];
265 free (s->comdat_key);
272 /* Free all remaining memory. */
278 for (i = 0; i < num_claimed_files; i++)
280 struct plugin_file_info *info = &claimed_files[i];
281 struct plugin_symtab *symtab = &info->symtab;
282 free (symtab->slots);
286 for (i = 0; i < num_output_files; i++)
287 free (output_files[i]);
290 free (claimed_files);
291 claimed_files = NULL;
292 num_claimed_files = 0;
294 if (arguments_file_name)
295 free (arguments_file_name);
296 arguments_file_name = NULL;
299 /* Writes the relocations to disk. */
302 write_resolution (void)
307 check (resolution_file, LDPL_FATAL, "resolution file not specified");
308 f = fopen (resolution_file, "w");
309 check (f, LDPL_FATAL, "could not open file");
311 fprintf (f, "%d\n", num_claimed_files);
313 for (i = 0; i < num_claimed_files; i++)
315 struct plugin_file_info *info = &claimed_files[i];
316 struct plugin_symtab *symtab = &info->symtab;
317 struct ld_plugin_symbol *syms = symtab->syms;
321 get_symbols (info->handle, symtab->nsyms, syms);
323 fprintf (f, "%s %d\n", info->name, info->symtab.nsyms);
325 for (j = 0; j < info->symtab.nsyms; j++)
327 uint32_t slot = symtab->slots[j];
328 unsigned int resolution = syms[j].resolution;
329 fprintf (f, "%d %s %s\n", slot, lto_resolution_str[resolution], syms[j].name);
335 /* Pass files generated by the lto-wrapper to the linker. FD is lto-wrapper's
339 add_output_files (FILE *f)
343 const unsigned piece = 32;
344 char *buf, *s = xmalloc (piece);
349 if (!fgets (buf, piece, f))
352 if (s[len - 1] != '\n')
354 s = xrealloc (s, len + piece);
362 = xrealloc (output_files, num_output_files * sizeof (char *));
363 output_files[num_output_files - 1] = s;
364 add_input_file (output_files[num_output_files - 1]);
368 /* Execute the lto-wrapper. ARGV[0] is the binary. The rest of ARGV is the
372 exec_lto_wrapper (char *argv[])
378 FILE *wrapper_output;
383 /* Write argv to a file to avoid a command line that is too long. */
384 arguments_file_name = make_temp_file ("");
385 check (arguments_file_name, LDPL_FATAL,
386 "Failed to generate a temorary file name");
388 args = fopen (arguments_file_name, "w");
389 check (args, LDPL_FATAL, "could not open arguments file");
391 t = writeargv (&argv[1], args);
392 check (t == 0, LDPL_FATAL, "could not write arguments");
394 check (t == 0, LDPL_FATAL, "could not close arguments file");
396 at_args = concat ("@", arguments_file_name, NULL);
397 check (at_args, LDPL_FATAL, "could not allocate");
399 for (i = 1; argv[i]; i++)
402 if (a[0] == '-' && a[1] == 'v' && a[2] == '\0')
404 for (i = 0; argv[i]; i++)
405 fprintf (stderr, "%s ", argv[i]);
406 fprintf (stderr, "\n");
411 new_argv[0] = argv[0];
412 new_argv[1] = at_args;
417 for (i = 0; new_argv[i]; i++)
418 fprintf (stderr, "%s ", new_argv[i]);
419 fprintf (stderr, "\n");
423 pex = pex_init (PEX_USE_PIPES, "lto-wrapper", NULL);
424 check (pex != NULL, LDPL_FATAL, "could not pex_init lto-wrapper");
426 errmsg = pex_run (pex, 0, new_argv[0], new_argv, NULL, NULL, &t);
427 check (errmsg == NULL, LDPL_FATAL, "could not run lto-wrapper");
428 check (t == 0, LDPL_FATAL, "could not run lto-wrapper");
430 wrapper_output = pex_read_output (pex, 0);
431 check (wrapper_output, LDPL_FATAL, "could not read lto-wrapper output");
433 add_output_files (wrapper_output);
435 t = pex_get_status (pex, 1, &status);
436 check (t == 1, LDPL_FATAL, "could not get lto-wrapper exit status");
437 check (WIFEXITED (status) && WEXITSTATUS (status) == 0, LDPL_FATAL,
438 "lto-wrapper failed");
445 /* Pass the original files back to the linker. */
448 use_original_files (void)
451 for (i = 0; i < num_claimed_files; i++)
453 struct plugin_file_info *info = &claimed_files[i];
454 add_input_file (info->name);
459 /* Called by the linker once all symbols have been read. */
461 static enum ld_plugin_status
462 all_symbols_read_handler (void)
465 unsigned num_lto_args = num_claimed_files + lto_wrapper_num_args + 1;
467 const char **lto_arg_ptr;
468 if (num_claimed_files == 0)
473 use_original_files ();
477 lto_argv = (char **) xcalloc (sizeof (char *), num_lto_args);
478 lto_arg_ptr = (const char **) lto_argv;
479 assert (lto_wrapper_argv);
485 for (i = 0; i < lto_wrapper_num_args; i++)
486 *lto_arg_ptr++ = lto_wrapper_argv[i];
488 for (i = 0; i < num_claimed_files; i++)
490 struct plugin_file_info *info = &claimed_files[i];
492 *lto_arg_ptr++ = info->name;
495 *lto_arg_ptr++ = NULL;
496 exec_lto_wrapper (lto_argv);
500 if (pass_through_items)
503 for (i = 0; i < num_pass_through_items; i++)
505 if (strncmp (pass_through_items[i], "-l", 2) == 0)
506 add_input_library (pass_through_items[i] + 2);
508 add_input_file (pass_through_items[i]);
509 free (pass_through_items[i]);
510 pass_through_items[i] = NULL;
512 free (pass_through_items);
513 pass_through_items = NULL;
519 /* Remove temporary files at the end of the link. */
521 static enum ld_plugin_status
522 cleanup_handler (void)
530 if (arguments_file_name)
532 t = unlink (arguments_file_name);
533 check (t == 0, LDPL_FATAL, "could not unlink arguments file");
536 for (i = 0; i < num_output_files; i++)
538 t = unlink (output_files[i]);
539 check (t == 0, LDPL_FATAL, "could not unlink output file");
542 for (i = 0; i < num_output_files; i++)
544 t = unlink (output_files[i]);
545 check (t == 0, LDPL_FATAL, "could not unlink output file");
552 /* Callback used by gold to check if the plugin will claim FILE. Writes
553 the result in CLAIMED. */
555 static enum ld_plugin_status
556 claim_file_handler (const struct ld_plugin_input_file *file, int *claimed)
558 enum ld_plugin_status status;
560 struct plugin_file_info lto_file;
563 if (file->offset != 0)
568 /* We pass the offset of the actual file, not the archive header. */
569 int t = asprintf (&objname, "%s@0x%" PRIx64, file->name,
570 (int64_t) file->offset);
571 check (t >= 0, LDPL_FATAL, "asprintf failed");
572 lto_file.name = objname;
574 archive = elf_begin (file->fd, ELF_C_READ, NULL);
575 check (elf_kind (archive) == ELF_K_AR, LDPL_FATAL,
576 "Not an archive and offset not 0");
578 /* elf_rand expects the offset to point to the ar header, not the
579 object itself. Subtract the size of the ar header (60 bytes).
580 We don't uses sizeof (struct ar_hd) to avoid including ar.h */
582 offset = file->offset - 60;
583 check (offset == elf_rand (archive, offset), LDPL_FATAL,
584 "could not seek in archive");
585 elf = elf_begin (file->fd, ELF_C_READ, archive);
586 check (elf != NULL, LDPL_FATAL, "could not find archive member");
591 lto_file.name = xstrdup (file->name);
592 elf = elf_begin (file->fd, ELF_C_READ, NULL);
594 lto_file.handle = file->handle;
601 symtab = get_symtab (elf);
605 translate (symtab, <o_file.symtab);
607 status = add_symbols (file->handle, lto_file.symtab.nsyms,
608 lto_file.symtab.syms);
609 check (status == LDPS_OK, LDPL_FATAL, "could not add symbols");
614 xrealloc (claimed_files,
615 num_claimed_files * sizeof (struct plugin_file_info));
616 claimed_files[num_claimed_files - 1] = lto_file;
621 free (lto_file.name);
630 /* Parse the plugin options. */
633 process_option (const char *option)
635 if (strcmp (option, "-debug") == 0)
637 else if (strcmp (option, "-nop") == 0)
639 else if (!strncmp (option, "-pass-through=", strlen("-pass-through=")))
641 num_pass_through_items++;
642 pass_through_items = xrealloc (pass_through_items,
643 num_pass_through_items * sizeof (char *));
644 pass_through_items[num_pass_through_items - 1] =
645 xstrdup (option + strlen ("-pass-through="));
650 char *opt = xstrdup (option);
651 lto_wrapper_num_args += 1;
652 size = lto_wrapper_num_args * sizeof (char *);
653 lto_wrapper_argv = (char **) xrealloc (lto_wrapper_argv, size);
654 lto_wrapper_argv[lto_wrapper_num_args - 1] = opt;
655 if (strncmp (option, "-fresolution=", sizeof ("-fresolution=") - 1) == 0)
656 resolution_file = opt + sizeof ("-fresolution=") - 1;
660 /* Called by gold after loading the plugin. TV is the transfer vector. */
662 enum ld_plugin_status
663 onload (struct ld_plugin_tv *tv)
665 struct ld_plugin_tv *p;
666 enum ld_plugin_status status;
668 unsigned version = elf_version (EV_CURRENT);
669 check (version != EV_NONE, LDPL_FATAL, "invalid ELF version");
677 message = p->tv_u.tv_message;
679 case LDPT_REGISTER_CLAIM_FILE_HOOK:
680 register_claim_file = p->tv_u.tv_register_claim_file;
682 case LDPT_ADD_SYMBOLS:
683 add_symbols = p->tv_u.tv_add_symbols;
685 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK:
686 register_all_symbols_read = p->tv_u.tv_register_all_symbols_read;
688 case LDPT_GET_SYMBOLS:
689 get_symbols = p->tv_u.tv_get_symbols;
691 case LDPT_REGISTER_CLEANUP_HOOK:
692 register_cleanup = p->tv_u.tv_register_cleanup;
694 case LDPT_ADD_INPUT_FILE:
695 add_input_file = p->tv_u.tv_add_input_file;
697 case LDPT_ADD_INPUT_LIBRARY:
698 add_input_library = p->tv_u.tv_add_input_library;
701 process_option (p->tv_u.tv_string);
709 check (register_claim_file, LDPL_FATAL, "register_claim_file not found");
710 check (add_symbols, LDPL_FATAL, "add_symbols not found");
711 status = register_claim_file (claim_file_handler);
712 check (status == LDPS_OK, LDPL_FATAL,
713 "could not register the claim_file callback");
715 if (register_cleanup)
717 status = register_cleanup (cleanup_handler);
718 check (status == LDPS_OK, LDPL_FATAL,
719 "could not register the cleanup callback");
722 if (register_all_symbols_read)
724 check (get_symbols, LDPL_FATAL, "get_symbols not found");
725 status = register_all_symbols_read (all_symbols_read_handler);
726 check (status == LDPS_OK, LDPL_FATAL,
727 "could not register the all_symbols_read callback");