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;
320 get_symbols (info->handle, symtab->nsyms, syms);
322 fprintf (f, "%s %d\n", info->name, info->symtab.nsyms);
324 for (j = 0; j < info->symtab.nsyms; j++)
326 uint32_t slot = symtab->slots[j];
327 unsigned int resolution = syms[j].resolution;
328 fprintf (f, "%d %s %s\n", slot, lto_resolution_str[resolution], syms[j].name);
334 /* Pass files generated by the lto-wrapper to the linker. FD is lto-wrapper's
338 add_output_files (FILE *f)
342 const unsigned piece = 32;
343 char *buf, *s = xmalloc (piece);
348 if (!fgets (buf, piece, f))
351 if (s[len - 1] != '\n')
353 s = xrealloc (s, len + piece);
361 = xrealloc (output_files, num_output_files * sizeof (char *));
362 output_files[num_output_files - 1] = s;
363 add_input_file (output_files[num_output_files - 1]);
367 /* Execute the lto-wrapper. ARGV[0] is the binary. The rest of ARGV is the
371 exec_lto_wrapper (char *argv[])
377 FILE *wrapper_output;
382 /* Write argv to a file to avoid a command line that is too long. */
383 arguments_file_name = make_temp_file ("");
384 check (arguments_file_name, LDPL_FATAL,
385 "Failed to generate a temorary file name");
387 args = fopen (arguments_file_name, "w");
388 check (args, LDPL_FATAL, "could not open arguments file");
390 t = writeargv (&argv[1], args);
391 check (t == 0, LDPL_FATAL, "could not write arguments");
393 check (t == 0, LDPL_FATAL, "could not close arguments file");
395 at_args = concat ("@", arguments_file_name, NULL);
396 check (at_args, LDPL_FATAL, "could not allocate");
398 for (i = 1; argv[i]; i++)
401 if (a[0] == '-' && a[1] == 'v' && a[2] == '\0')
403 for (i = 0; argv[i]; i++)
404 fprintf (stderr, "%s ", argv[i]);
405 fprintf (stderr, "\n");
410 new_argv[0] = argv[0];
411 new_argv[1] = at_args;
416 for (i = 0; new_argv[i]; i++)
417 fprintf (stderr, "%s ", new_argv[i]);
418 fprintf (stderr, "\n");
422 pex = pex_init (PEX_USE_PIPES, "lto-wrapper", NULL);
423 check (pex != NULL, LDPL_FATAL, "could not pex_init lto-wrapper");
425 errmsg = pex_run (pex, 0, new_argv[0], new_argv, NULL, NULL, &t);
426 check (errmsg == NULL, LDPL_FATAL, "could not run lto-wrapper");
427 check (t == 0, LDPL_FATAL, "could not run lto-wrapper");
429 wrapper_output = pex_read_output (pex, 0);
430 check (wrapper_output, LDPL_FATAL, "could not read lto-wrapper output");
432 add_output_files (wrapper_output);
434 t = pex_get_status (pex, 1, &status);
435 check (t == 1, LDPL_FATAL, "could not get lto-wrapper exit status");
436 check (WIFEXITED (status) && WEXITSTATUS (status) == 0, LDPL_FATAL,
437 "lto-wrapper failed");
444 /* Pass the original files back to the linker. */
447 use_original_files (void)
450 for (i = 0; i < num_claimed_files; i++)
452 struct plugin_file_info *info = &claimed_files[i];
453 add_input_file (info->name);
458 /* Called by the linker once all symbols have been read. */
460 static enum ld_plugin_status
461 all_symbols_read_handler (void)
464 unsigned num_lto_args = num_claimed_files + lto_wrapper_num_args + 1;
466 const char **lto_arg_ptr;
467 if (num_claimed_files == 0)
472 use_original_files ();
476 lto_argv = (char **) xcalloc (sizeof (char *), num_lto_args);
477 lto_arg_ptr = (const char **) lto_argv;
478 assert (lto_wrapper_argv);
484 for (i = 0; i < lto_wrapper_num_args; i++)
485 *lto_arg_ptr++ = lto_wrapper_argv[i];
487 for (i = 0; i < num_claimed_files; i++)
489 struct plugin_file_info *info = &claimed_files[i];
491 *lto_arg_ptr++ = info->name;
494 *lto_arg_ptr++ = NULL;
495 exec_lto_wrapper (lto_argv);
499 if (pass_through_items)
502 for (i = 0; i < num_pass_through_items; i++)
504 if (strncmp (pass_through_items[i], "-l", 2) == 0)
505 add_input_library (pass_through_items[i] + 2);
507 add_input_file (pass_through_items[i]);
508 free (pass_through_items[i]);
509 pass_through_items[i] = NULL;
511 free (pass_through_items);
512 pass_through_items = NULL;
518 /* Remove temporary files at the end of the link. */
520 static enum ld_plugin_status
521 cleanup_handler (void)
529 if (arguments_file_name)
531 t = unlink (arguments_file_name);
532 check (t == 0, LDPL_FATAL, "could not unlink arguments file");
535 for (i = 0; i < num_output_files; i++)
537 t = unlink (output_files[i]);
538 check (t == 0, LDPL_FATAL, "could not unlink output file");
541 for (i = 0; i < num_output_files; i++)
543 t = unlink (output_files[i]);
544 check (t == 0, LDPL_FATAL, "could not unlink output file");
551 /* Callback used by gold to check if the plugin will claim FILE. Writes
552 the result in CLAIMED. */
554 static enum ld_plugin_status
555 claim_file_handler (const struct ld_plugin_input_file *file, int *claimed)
557 enum ld_plugin_status status;
559 struct plugin_file_info lto_file;
562 if (file->offset != 0)
567 /* We pass the offset of the actual file, not the archive header. */
568 int t = asprintf (&objname, "%s@0x%" PRIx64, file->name,
569 (int64_t) file->offset);
570 check (t >= 0, LDPL_FATAL, "asprintf failed");
571 lto_file.name = objname;
573 archive = elf_begin (file->fd, ELF_C_READ, NULL);
574 check (elf_kind (archive) == ELF_K_AR, LDPL_FATAL,
575 "Not an archive and offset not 0");
577 /* elf_rand expects the offset to point to the ar header, not the
578 object itself. Subtract the size of the ar header (60 bytes).
579 We don't uses sizeof (struct ar_hd) to avoid including ar.h */
581 offset = file->offset - 60;
582 check (offset == elf_rand (archive, offset), LDPL_FATAL,
583 "could not seek in archive");
584 elf = elf_begin (file->fd, ELF_C_READ, archive);
585 check (elf != NULL, LDPL_FATAL, "could not find archive member");
590 lto_file.name = xstrdup (file->name);
591 elf = elf_begin (file->fd, ELF_C_READ, NULL);
593 lto_file.handle = file->handle;
600 symtab = get_symtab (elf);
604 translate (symtab, <o_file.symtab);
606 status = add_symbols (file->handle, lto_file.symtab.nsyms,
607 lto_file.symtab.syms);
608 check (status == LDPS_OK, LDPL_FATAL, "could not add symbols");
613 xrealloc (claimed_files,
614 num_claimed_files * sizeof (struct plugin_file_info));
615 claimed_files[num_claimed_files - 1] = lto_file;
620 free (lto_file.name);
629 /* Parse the plugin options. */
632 process_option (const char *option)
634 if (strcmp (option, "-debug") == 0)
636 else if (strcmp (option, "-nop") == 0)
638 else if (!strncmp (option, "-pass-through=", strlen("-pass-through=")))
640 num_pass_through_items++;
641 pass_through_items = xrealloc (pass_through_items,
642 num_pass_through_items * sizeof (char *));
643 pass_through_items[num_pass_through_items - 1] =
644 xstrdup (option + strlen ("-pass-through="));
649 char *opt = xstrdup (option);
650 lto_wrapper_num_args += 1;
651 size = lto_wrapper_num_args * sizeof (char *);
652 lto_wrapper_argv = (char **) xrealloc (lto_wrapper_argv, size);
653 lto_wrapper_argv[lto_wrapper_num_args - 1] = opt;
654 if (strncmp (option, "-fresolution=", sizeof ("-fresolution=") - 1) == 0)
655 resolution_file = opt + sizeof ("-fresolution=") - 1;
659 /* Called by gold after loading the plugin. TV is the transfer vector. */
661 enum ld_plugin_status
662 onload (struct ld_plugin_tv *tv)
664 struct ld_plugin_tv *p;
665 enum ld_plugin_status status;
667 unsigned version = elf_version (EV_CURRENT);
668 check (version != EV_NONE, LDPL_FATAL, "invalid ELF version");
676 message = p->tv_u.tv_message;
678 case LDPT_REGISTER_CLAIM_FILE_HOOK:
679 register_claim_file = p->tv_u.tv_register_claim_file;
681 case LDPT_ADD_SYMBOLS:
682 add_symbols = p->tv_u.tv_add_symbols;
684 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK:
685 register_all_symbols_read = p->tv_u.tv_register_all_symbols_read;
687 case LDPT_GET_SYMBOLS:
688 get_symbols = p->tv_u.tv_get_symbols;
690 case LDPT_REGISTER_CLEANUP_HOOK:
691 register_cleanup = p->tv_u.tv_register_cleanup;
693 case LDPT_ADD_INPUT_FILE:
694 add_input_file = p->tv_u.tv_add_input_file;
696 case LDPT_ADD_INPUT_LIBRARY:
697 add_input_library = p->tv_u.tv_add_input_library;
700 process_option (p->tv_u.tv_string);
708 check (register_claim_file, LDPL_FATAL, "register_claim_file not found");
709 check (add_symbols, LDPL_FATAL, "add_symbols not found");
710 status = register_claim_file (claim_file_handler);
711 check (status == LDPS_OK, LDPL_FATAL,
712 "could not register the claim_file callback");
714 if (register_cleanup)
716 status = register_cleanup (cleanup_handler);
717 check (status == LDPS_OK, LDPL_FATAL,
718 "could not register the cleanup callback");
721 if (register_all_symbols_read)
723 check (get_symbols, LDPL_FATAL, "get_symbols not found");
724 status = register_all_symbols_read (all_symbols_read_handler);
725 check (status == LDPS_OK, LDPL_FATAL,
726 "could not register the all_symbols_read callback");