2 Copyright 2001, 2002, 2003 Free Software Foundation, Inc.
3 Written by Jakub Jelinek <jakub@redhat.com>.
5 This file is part of BFD, the Binary File Descriptor library.
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program; if not, write to the Free Software
19 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
21 /* This file contains support for merging duplicate entities within sections,
22 as used in ELF SHF_MERGE. */
28 #include "libiberty.h"
30 struct sec_merge_sec_info;
32 /* An entry in the section merge hash table. */
34 struct sec_merge_hash_entry
36 struct bfd_hash_entry root;
37 /* Length of this entry. */
39 /* Start of this string needs to be aligned to
40 alignment octets (not 1 << align). */
41 unsigned int alignment;
44 /* Index within the merged section. */
46 /* Entity size (if present in suffix hash tables). */
48 /* Entry this is a suffix of (if alignment is 0). */
49 struct sec_merge_hash_entry *suffix;
51 /* Which section is it in. */
52 struct sec_merge_sec_info *secinfo;
53 /* Next entity in the hash table. */
54 struct sec_merge_hash_entry *next;
57 /* The section merge hash table. */
61 struct bfd_hash_table table;
62 /* Next available index. */
64 /* First entity in the SEC_MERGE sections of this type. */
65 struct sec_merge_hash_entry *first;
66 /* Last entity in the SEC_MERGE sections of this type. */
67 struct sec_merge_hash_entry *last;
70 /* Are entries fixed size or zero terminated strings? */
76 /* Chain of sec_merge_infos. */
77 struct sec_merge_info *next;
78 /* Chain of sec_merge_sec_infos. */
79 struct sec_merge_sec_info *chain;
80 /* A hash table used to hold section content. */
81 struct sec_merge_hash *htab;
84 struct sec_merge_sec_info
86 /* Chain of sec_merge_sec_infos. */
87 struct sec_merge_sec_info *next;
88 /* The corresponding section. */
90 /* Pointer to merge_info pointing to us. */
92 /* A hash table used to hold section content. */
93 struct sec_merge_hash *htab;
94 /* First string in this section. */
95 struct sec_merge_hash_entry *first;
96 /* Original section content. */
97 unsigned char contents[1];
101 /* Routine to create an entry in a section merge hashtab. */
103 static struct bfd_hash_entry *
104 sec_merge_hash_newfunc (struct bfd_hash_entry *entry,
105 struct bfd_hash_table *table, const char *string)
107 struct sec_merge_hash_entry *ret = (struct sec_merge_hash_entry *) entry;
109 /* Allocate the structure if it has not already been allocated by a
111 if (ret == (struct sec_merge_hash_entry *) NULL)
112 ret = ((struct sec_merge_hash_entry *)
113 bfd_hash_allocate (table, sizeof (struct sec_merge_hash_entry)));
114 if (ret == (struct sec_merge_hash_entry *) NULL)
117 /* Call the allocation method of the superclass. */
118 ret = ((struct sec_merge_hash_entry *)
119 bfd_hash_newfunc ((struct bfd_hash_entry *) ret, table, string));
123 /* Initialize the local fields. */
124 ret->u.suffix = NULL;
130 return (struct bfd_hash_entry *) ret;
133 /* Look up an entry in a section merge hash table. */
135 static struct sec_merge_hash_entry *
136 sec_merge_hash_lookup (struct sec_merge_hash *table, const char *string,
137 unsigned int alignment, bfd_boolean create)
139 register const unsigned char *s;
140 register unsigned long hash;
141 register unsigned int c;
142 struct sec_merge_hash_entry *hashp;
148 s = (const unsigned char *) string;
151 if (table->entsize == 1)
153 while ((c = *s++) != '\0')
155 hash += c + (c << 17);
159 hash += len + (len << 17);
165 for (i = 0; i < table->entsize; ++i)
168 if (i == table->entsize)
170 for (i = 0; i < table->entsize; ++i)
173 hash += c + (c << 17);
178 hash += len + (len << 17);
179 len *= table->entsize;
182 len += table->entsize;
186 for (i = 0; i < table->entsize; ++i)
189 hash += c + (c << 17);
192 len = table->entsize;
195 index = hash % table->table.size;
196 for (hashp = (struct sec_merge_hash_entry *) table->table.table[index];
197 hashp != (struct sec_merge_hash_entry *) NULL;
198 hashp = (struct sec_merge_hash_entry *) hashp->root.next)
200 if (hashp->root.hash == hash
202 && memcmp (hashp->root.string, string, len) == 0)
204 /* If the string we found does not have at least the required
205 alignment, we need to insert another copy. */
206 if (hashp->alignment < alignment)
208 /* Mark the less aligned copy as deleted. */
210 hashp->alignment = 0;
218 return (struct sec_merge_hash_entry *) NULL;
220 hashp = (struct sec_merge_hash_entry *)
221 sec_merge_hash_newfunc ((struct bfd_hash_entry *) NULL,
222 (struct bfd_hash_table *) table, string);
223 if (hashp == (struct sec_merge_hash_entry *) NULL)
224 return (struct sec_merge_hash_entry *) NULL;
225 hashp->root.string = string;
226 hashp->root.hash = hash;
228 hashp->alignment = alignment;
229 hashp->root.next = table->table.table[index];
230 table->table.table[index] = (struct bfd_hash_entry *) hashp;
235 /* Create a new hash table. */
237 static struct sec_merge_hash *
238 sec_merge_init (unsigned int entsize, bfd_boolean strings)
240 struct sec_merge_hash *table;
241 bfd_size_type amt = sizeof (struct sec_merge_hash);
243 table = (struct sec_merge_hash *) bfd_malloc (amt);
247 if (! bfd_hash_table_init (&table->table, sec_merge_hash_newfunc))
256 table->entsize = entsize;
257 table->strings = strings;
262 /* Get the index of an entity in a hash table, adding it if it is not
265 static struct sec_merge_hash_entry *
266 sec_merge_add (struct sec_merge_hash *tab, const char *str,
267 unsigned int alignment, struct sec_merge_sec_info *secinfo)
269 register struct sec_merge_hash_entry *entry;
271 entry = sec_merge_hash_lookup (tab, str, alignment, TRUE);
275 if (entry->secinfo == NULL)
278 entry->secinfo = secinfo;
279 if (tab->first == NULL)
282 tab->last->next = entry;
290 sec_merge_emit (register bfd *abfd, struct sec_merge_hash_entry *entry)
292 struct sec_merge_sec_info *secinfo = entry->secinfo;
293 asection *sec = secinfo->sec;
295 bfd_size_type off = 0;
296 int alignment_power = bfd_get_section_alignment (abfd, sec->output_section);
299 pad = bfd_zmalloc ((bfd_size_type) 1 << alignment_power);
301 for (; entry != NULL && entry->secinfo == secinfo; entry = entry->next)
303 register const char *str;
306 len = off & (entry->alignment - 1);
309 len = entry->alignment - len;
310 if (bfd_bwrite (pad, (bfd_size_type) len, abfd) != len)
315 str = entry->root.string;
318 if (bfd_bwrite (str, (bfd_size_type) len, abfd) != len)
327 return entry == NULL || entry->secinfo != secinfo;
330 /* This function is called for each input file from the add_symbols
331 pass of the linker. */
334 _bfd_merge_section (bfd *abfd, void **psinfo, asection *sec, void **psecinfo)
336 struct sec_merge_info *sinfo;
337 struct sec_merge_sec_info *secinfo;
341 if (sec->_raw_size == 0
342 || (sec->flags & SEC_EXCLUDE)
343 || (sec->flags & SEC_MERGE) == 0
344 || sec->entsize == 0)
347 if ((sec->flags & SEC_RELOC) != 0)
349 /* We aren't prepared to handle relocations in merged sections. */
353 align = bfd_get_section_alignment (sec->owner, sec);
354 if ((sec->entsize < (unsigned int)(1 << align)
355 && ((sec->entsize & (sec->entsize - 1))
356 || !(sec->flags & SEC_STRINGS)))
357 || (sec->entsize > (unsigned int)(1 << align)
358 && (sec->entsize & ((1 << align) - 1))))
360 /* Sanity check. If string character size is smaller than
361 alignment, then we require character size to be a power
362 of 2, otherwise character size must be integer multiple
363 of alignment. For non-string constants, alignment must
364 be smaller than or equal to entity size and entity size
365 must be integer multiple of alignment. */
369 for (sinfo = (struct sec_merge_info *) *psinfo; sinfo; sinfo = sinfo->next)
370 if ((secinfo = sinfo->chain)
371 && ! ((secinfo->sec->flags ^ sec->flags) & (SEC_MERGE | SEC_STRINGS))
372 && secinfo->sec->entsize == sec->entsize
373 && ! strcmp (secinfo->sec->name, sec->name))
378 /* Initialize the information we need to keep track of. */
379 amt = sizeof (struct sec_merge_info);
380 sinfo = (struct sec_merge_info *) bfd_alloc (abfd, amt);
383 sinfo->next = (struct sec_merge_info *) *psinfo;
386 sinfo->htab = sec_merge_init (sec->entsize, (sec->flags & SEC_STRINGS));
387 if (sinfo->htab == NULL)
391 /* Read the section from abfd. */
393 amt = sizeof (struct sec_merge_sec_info) + sec->_raw_size - 1;
394 *psecinfo = bfd_alloc (abfd, amt);
395 if (*psecinfo == NULL)
398 secinfo = (struct sec_merge_sec_info *)*psecinfo;
401 secinfo->next = sinfo->chain->next;
402 sinfo->chain->next = secinfo;
405 secinfo->next = secinfo;
406 sinfo->chain = secinfo;
408 secinfo->psecinfo = psecinfo;
409 secinfo->htab = sinfo->htab;
410 secinfo->first = NULL;
412 if (! bfd_get_section_contents (sec->owner, sec, secinfo->contents,
413 (bfd_vma) 0, sec->_raw_size))
423 /* Compare two sec_merge_hash_entry structures. This is called via qsort. */
426 cmplengthentry (const void *a, const void *b)
428 struct sec_merge_hash_entry * A = *(struct sec_merge_hash_entry **) a;
429 struct sec_merge_hash_entry * B = *(struct sec_merge_hash_entry **) b;
433 else if (A->len > B->len)
436 return memcmp (A->root.string, B->root.string, A->len);
440 last4_eq (const void *a, const void *b)
442 struct sec_merge_hash_entry * A = (struct sec_merge_hash_entry *) a;
443 struct sec_merge_hash_entry * B = (struct sec_merge_hash_entry *) b;
445 if (memcmp (A->root.string + A->len - 5 * A->u.entsize,
446 B->root.string + B->len - 5 * A->u.entsize,
447 4 * A->u.entsize) != 0)
448 /* This was a hashtable collision. */
451 if (A->len <= B->len)
452 /* B cannot be a suffix of A unless A is equal to B, which is guaranteed
453 not to be equal by the hash table. */
456 if (A->alignment < B->alignment
457 || ((A->len - B->len) & (B->alignment - 1)))
458 /* The suffix is not sufficiently aligned. */
461 return memcmp (A->root.string + (A->len - B->len),
462 B->root.string, B->len - 5 * A->u.entsize) == 0;
466 last_eq (const void *a, const void *b)
468 struct sec_merge_hash_entry * A = (struct sec_merge_hash_entry *) a;
469 struct sec_merge_hash_entry * B = (struct sec_merge_hash_entry *) b;
471 if (B->len >= 5 * A->u.entsize)
472 /* Longer strings are just pushed into the hash table,
473 they'll be used when looking up for very short strings. */
476 if (memcmp (A->root.string + A->len - 2 * A->u.entsize,
477 B->root.string + B->len - 2 * A->u.entsize,
479 /* This was a hashtable collision. */
482 if (A->len <= B->len)
483 /* B cannot be a suffix of A unless A is equal to B, which is guaranteed
484 not to be equal by the hash table. */
487 if (A->alignment < B->alignment
488 || ((A->len - B->len) & (B->alignment - 1)))
489 /* The suffix is not sufficiently aligned. */
492 return memcmp (A->root.string + (A->len - B->len),
493 B->root.string, B->len - 2 * A->u.entsize) == 0;
496 /* Record one section into the hash table. */
498 record_section (struct sec_merge_info *sinfo,
499 struct sec_merge_sec_info *secinfo)
501 asection *sec = secinfo->sec;
502 struct sec_merge_hash_entry *entry;
504 unsigned char *p, *end;
505 bfd_vma mask, eltalign;
506 unsigned int align, i;
508 align = bfd_get_section_alignment (sec->owner, sec);
509 end = secinfo->contents + sec->_raw_size;
511 mask = ((bfd_vma) 1 << align) - 1;
512 if (sec->flags & SEC_STRINGS)
514 for (p = secinfo->contents; p < end; )
516 eltalign = p - secinfo->contents;
517 eltalign = ((eltalign ^ (eltalign - 1)) + 1) >> 1;
518 if (!eltalign || eltalign > mask)
520 entry = sec_merge_add (sinfo->htab, p, (unsigned) eltalign, secinfo);
524 if (sec->entsize == 1)
526 while (p < end && *p == 0)
528 if (!nul && !((p - secinfo->contents) & mask))
531 entry = sec_merge_add (sinfo->htab, "",
532 (unsigned) mask + 1, secinfo);
543 for (i = 0; i < sec->entsize; i++)
546 if (i != sec->entsize)
548 if (!nul && !((p - secinfo->contents) & mask))
551 entry = sec_merge_add (sinfo->htab, p,
552 (unsigned) mask + 1, secinfo);
563 for (p = secinfo->contents; p < end; p += sec->entsize)
565 entry = sec_merge_add (sinfo->htab, p, 1, secinfo);
574 for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
575 *secinfo->psecinfo = NULL;
579 /* This is a helper function for _bfd_merge_sections. It attempts to
580 merge strings matching suffixes of longer strings. */
582 merge_strings (struct sec_merge_info *sinfo)
584 struct sec_merge_hash_entry **array, **a, **end, *e;
585 struct sec_merge_sec_info *secinfo;
586 htab_t lasttab = NULL, last4tab = NULL;
587 bfd_size_type size, amt;
589 /* Now sort the strings by length, longest first. */
591 amt = sinfo->htab->size * sizeof (struct sec_merge_hash_entry *);
592 array = (struct sec_merge_hash_entry **) bfd_malloc (amt);
596 for (e = sinfo->htab->first, a = array; e; e = e->next)
600 sinfo->htab->size = a - array;
602 qsort (array, (size_t) sinfo->htab->size,
603 sizeof (struct sec_merge_hash_entry *), cmplengthentry);
605 last4tab = htab_create_alloc ((size_t) sinfo->htab->size * 4,
606 NULL, last4_eq, NULL, calloc, free);
607 lasttab = htab_create_alloc ((size_t) sinfo->htab->size * 4,
608 NULL, last_eq, NULL, calloc, free);
609 if (lasttab == NULL || last4tab == NULL)
612 /* Now insert the strings into hash tables (strings with last 4 characters
613 and strings with last character equal), look for longer strings which
615 for (a = array, end = array + sinfo->htab->size; a < end; a++)
617 register hashval_t hash;
620 const unsigned char *s;
624 e->u.entsize = sinfo->htab->entsize;
625 if (e->len <= e->u.entsize)
627 if (e->len > 4 * e->u.entsize)
629 s = (const unsigned char *) (e->root.string + e->len - e->u.entsize);
631 for (i = 0; i < 4 * e->u.entsize; i++)
634 hash += c + (c << 17);
637 p = htab_find_slot_with_hash (last4tab, e, hash, INSERT);
642 struct sec_merge_hash_entry *ent;
644 ent = (struct sec_merge_hash_entry *) *p;
652 s = (const unsigned char *) (e->root.string + e->len - e->u.entsize);
654 for (i = 0; i < e->u.entsize; i++)
657 hash += c + (c << 17);
660 p = htab_find_slot_with_hash (lasttab, e, hash, INSERT);
665 struct sec_merge_hash_entry *ent;
667 ent = (struct sec_merge_hash_entry *) *p;
679 htab_delete (lasttab);
681 htab_delete (last4tab);
683 /* Now assign positions to the strings we want to keep. */
685 secinfo = sinfo->htab->first->secinfo;
686 for (e = sinfo->htab->first; e; e = e->next)
688 if (e->secinfo != secinfo)
690 secinfo->sec->_cooked_size = size;
691 secinfo = e->secinfo;
695 if (e->secinfo->first == NULL)
697 e->secinfo->first = e;
700 size = (size + e->alignment - 1) & ~((bfd_vma) e->alignment - 1);
705 secinfo->sec->_cooked_size = size;
707 /* And now adjust the rest, removing them from the chain (but not hashtable)
709 for (a = &sinfo->htab->first, e = *a; e; e = e->next)
717 e->secinfo = e->u.suffix->secinfo;
718 e->alignment = e->u.suffix->alignment;
719 e->u.index = e->u.suffix->u.index + (e->u.suffix->len - e->len);
724 /* This function is called once after all SEC_MERGE sections are registered
725 with _bfd_merge_section. */
728 _bfd_merge_sections (bfd *abfd ATTRIBUTE_UNUSED, void *xsinfo,
729 void (*remove_hook) (bfd *, asection *))
731 struct sec_merge_info *sinfo;
733 for (sinfo = (struct sec_merge_info *) xsinfo; sinfo; sinfo = sinfo->next)
735 struct sec_merge_sec_info * secinfo;
740 /* Move sinfo->chain to head of the chain, terminate it. */
741 secinfo = sinfo->chain;
742 sinfo->chain = secinfo->next;
743 secinfo->next = NULL;
745 /* Record the sections into the hash table. */
746 for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
747 if (secinfo->sec->flags & SEC_EXCLUDE)
749 *secinfo->psecinfo = NULL;
751 (*remove_hook) (abfd, secinfo->sec);
753 else if (! record_section (sinfo, secinfo))
759 if (sinfo->htab->first == NULL)
762 if (sinfo->htab->strings)
763 merge_strings (sinfo);
766 struct sec_merge_hash_entry *e;
767 bfd_size_type size = 0;
769 /* Things are much simpler for non-strings.
770 Just assign them slots in the section. */
772 for (e = sinfo->htab->first; e; e = e->next)
774 if (e->secinfo->first == NULL)
777 secinfo->sec->_cooked_size = size;
778 e->secinfo->first = e;
781 size = (size + e->alignment - 1)
782 & ~((bfd_vma) e->alignment - 1);
785 secinfo = e->secinfo;
787 secinfo->sec->_cooked_size = size;
790 /* Finally remove all input sections which have not made it into
791 the hash table at all. */
792 for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
793 if (secinfo->first == NULL)
795 secinfo->sec->_cooked_size = 0;
796 secinfo->sec->flags |= SEC_EXCLUDE;
803 /* Write out the merged section. */
806 _bfd_write_merged_section (bfd *output_bfd, asection *sec, void *psecinfo)
808 struct sec_merge_sec_info *secinfo;
811 secinfo = (struct sec_merge_sec_info *) psecinfo;
816 pos = sec->output_section->filepos + sec->output_offset;
817 if (bfd_seek (output_bfd, pos, SEEK_SET) != 0)
820 if (! sec_merge_emit (output_bfd, secinfo->first))
826 /* Adjust an address in the SEC_MERGE section. Given OFFSET within
827 *PSEC, this returns the new offset in the adjusted SEC_MERGE
828 section and writes the new section back into *PSEC. */
831 _bfd_merged_section_offset (bfd *output_bfd ATTRIBUTE_UNUSED, asection **psec,
832 void *psecinfo, bfd_vma offset, bfd_vma addend)
834 struct sec_merge_sec_info *secinfo;
835 struct sec_merge_hash_entry *entry;
837 asection *sec = *psec;
839 secinfo = (struct sec_merge_sec_info *) psecinfo;
841 if (offset + addend >= sec->_raw_size)
843 if (offset + addend > sec->_raw_size)
845 (*_bfd_error_handler)
846 (_("%s: access beyond end of merged section (%ld + %ld)"),
847 bfd_get_filename (sec->owner), (long) offset, (long) addend);
849 return (secinfo->first ? sec->_cooked_size : 0);
852 if (secinfo->htab->strings)
854 if (sec->entsize == 1)
856 p = secinfo->contents + offset + addend - 1;
857 while (p >= secinfo->contents && *p)
863 p = secinfo->contents
864 + ((offset + addend) / sec->entsize) * sec->entsize;
866 while (p >= secinfo->contents)
870 for (i = 0; i < sec->entsize; ++i)
873 if (i == sec->entsize)
882 p = secinfo->contents
883 + ((offset + addend) / sec->entsize) * sec->entsize;
885 entry = sec_merge_hash_lookup (secinfo->htab, p, 0, FALSE);
888 if (! secinfo->htab->strings)
890 /* This should only happen if somebody points into the padding
891 after a NUL character but before next entity. */
894 if (! secinfo->htab->first)
896 entry = secinfo->htab->first;
897 p = secinfo->contents
898 + ((offset + addend) / sec->entsize + 1) * sec->entsize
902 *psec = entry->secinfo->sec;
903 return entry->u.index + (secinfo->contents + offset - p);