-/* LTO plugin for gold.
- Copyright (C) 2009 Free Software Foundation, Inc.
+/* LTO plugin for gold and/or GNU ld.
+ Copyright (C) 2009, 2010 Free Software Foundation, Inc.
Contributed by Rafael Avila de Espindola (espindola@google.com).
This program is free software; you can redistribute it and/or modify
#include <sys/wait.h>
#include <stdbool.h>
#include <libiberty.h>
-
-/* The presence of gelf.h is checked by the toplevel configure script. */
-#include <gelf.h>
-
-#include "plugin-api.h"
+#include <hashtab.h>
#include "../gcc/lto/common.h"
-/* The part of the symbol table the plugin has to keep track of. Note that we
- must keep SYMS until all_symbols_read is called to give the linker time to
- copy the symbol information. */
-
-struct plugin_symtab
-{
- int nsyms;
- uint32_t *slots;
- struct ld_plugin_symbol *syms;
-};
-
-/* All that we have to remember about a file. */
-
-struct plugin_file_info
-{
- char *name;
- void *handle;
- struct plugin_symtab symtab;
-};
-
+/* Common definitions for/from the object format dependent code. */
+#include "lto-plugin.h"
static char *arguments_file_name;
static ld_plugin_register_claim_file register_claim_file;
-static ld_plugin_add_symbols add_symbols;
static ld_plugin_register_all_symbols_read register_all_symbols_read;
static ld_plugin_get_symbols get_symbols;
static ld_plugin_register_cleanup register_cleanup;
static ld_plugin_add_input_library add_input_library;
static ld_plugin_message message;
-static struct plugin_file_info *claimed_files = NULL;
-static unsigned int num_claimed_files = 0;
+/* These are not static because the object format dependent
+ claim_file hooks in lto-plugin-{coff,elf}.c need them. */
+ld_plugin_add_symbols add_symbols;
+
+struct plugin_file_info *claimed_files = NULL;
+unsigned int num_claimed_files = 0;
static char **output_files = NULL;
static unsigned int num_output_files = 0;
static bool nop;
static char *resolution_file = NULL;
-static void
+void
check (bool gate, enum ld_plugin_level level, const char *text)
{
if (gate)
by P and the result is written in ENTRY. The slot number is stored in SLOT.
Returns the address of the next entry. */
-static char *
-parse_table_entry (char *p, struct ld_plugin_symbol *entry, uint32_t *slot)
+char *
+parse_table_entry (char *p, struct ld_plugin_symbol *entry,
+ struct sym_aux *aux)
{
unsigned char t;
enum ld_plugin_symbol_kind translate_kind[] =
entry->size = *(uint64_t *) p;
p += 8;
- *slot = *(uint32_t *) p;
+ aux->slot = *(uint32_t *) p;
p += 4;
entry->resolution = LDPR_UNKNOWN;
- return p;
-}
-
-/* Return the section in ELF that is named NAME. */
+ aux->next_conflict = -1;
-static Elf_Scn *
-get_section (Elf *elf, const char *name)
-{
- Elf_Scn *section = 0;
- GElf_Ehdr header;
- GElf_Ehdr *t = gelf_getehdr (elf, &header);
- if (t == NULL)
- return NULL;
- assert (t == &header);
-
- while ((section = elf_nextscn(elf, section)) != 0)
- {
- GElf_Shdr shdr;
- GElf_Shdr *tshdr = gelf_getshdr (section, &shdr);
- const char *t;
- assert (tshdr == &shdr);
- t = elf_strptr (elf, header.e_shstrndx, shdr.sh_name);
- assert (t != NULL);
- if (strcmp (t, name) == 0)
- return section;
- }
- return NULL;
+ return p;
}
-/* Returns the IL symbol table of file ELF. */
+/* Translate the IL symbol table located between DATA and END. Append the
+ slots and symbols to OUT. */
-static Elf_Data *
-get_symtab (Elf *elf)
+void
+translate (char *data, char *end, struct plugin_symtab *out)
{
- Elf_Data *data = 0;
- Elf_Scn *section = get_section (elf, ".gnu.lto_.symtab");
- if (!section)
- return NULL;
-
- data = elf_getdata (section, data);
- assert (data);
- return data;
-}
-
-/* Translate the IL symbol table SYMTAB. Write the slots and symbols in OUT. */
-
-static void
-translate (Elf_Data *symtab, struct plugin_symtab *out)
-{
- uint32_t *slots = NULL;
- char *data = symtab->d_buf;
- char *end = data + symtab->d_size;
+ struct sym_aux *aux;
struct ld_plugin_symbol *syms = NULL;
- int n = 0;
-
- while (data < end)
- {
- n++;
- syms = xrealloc (syms, n * sizeof (struct ld_plugin_symbol));
- check (syms, LDPL_FATAL, "could not allocate memory");
- slots = xrealloc (slots, n * sizeof (uint32_t));
- check (slots, LDPL_FATAL, "could not allocate memory");
- data = parse_table_entry (data, &syms[n - 1], &slots[n - 1]);
+ int n, len;
+
+ /* This overestimates the output buffer sizes, but at least
+ the algorithm is O(1) now. */
+
+ len = (end - data)/8 + out->nsyms + 1;
+ syms = xrealloc (out->syms, len * sizeof (struct ld_plugin_symbol));
+ aux = xrealloc (out->aux, len * sizeof (struct sym_aux));
+
+ for (n = out->nsyms; data < end; n++)
+ {
+ aux[n].id = out->id;
+ data = parse_table_entry (data, &syms[n], &aux[n]);
}
+ assert(n < len);
+
out->nsyms = n;
out->syms = syms;
- out->slots = slots;
+ out->aux = aux;
}
/* Free all memory that is no longer needed after writing the symbol
{
struct plugin_file_info *info = &claimed_files[i];
struct plugin_symtab *symtab = &info->symtab;
- free (symtab->slots);
+ free (symtab->aux);
free (info->name);
}
arguments_file_name = NULL;
}
+/* Dump SYMTAB to resolution file F. */
+
+static void
+dump_symtab (FILE *f, struct plugin_symtab *symtab)
+{
+ unsigned j;
+
+ for (j = 0; j < symtab->nsyms; j++)
+ {
+ uint32_t slot = symtab->aux[j].slot;
+ unsigned int resolution = symtab->syms[j].resolution;
+
+ assert (resolution != LDPR_UNKNOWN);
+
+ fprintf (f, "%u %x %s %s\n", (unsigned int) slot, symtab->aux[j].id,
+ lto_resolution_str[resolution],
+ symtab->syms[j].name);
+ }
+}
+
+/* Finish the conflicts' resolution information after the linker resolved
+ the original symbols */
+
+static void
+finish_conflict_resolution (struct plugin_symtab *symtab,
+ struct plugin_symtab *conflicts)
+{
+ int i, j;
+
+ if (conflicts->nsyms == 0)
+ return;
+
+ for (i = 0; i < symtab->nsyms; i++)
+ {
+ int resolution = LDPR_UNKNOWN;
+
+ if (symtab->aux[i].next_conflict == -1)
+ continue;
+
+ switch (symtab->syms[i].def)
+ {
+ case LDPK_DEF:
+ case LDPK_COMMON: /* ??? */
+ resolution = LDPR_RESOLVED_IR;
+ break;
+ case LDPK_WEAKDEF:
+ resolution = LDPR_PREEMPTED_IR;
+ break;
+ case LDPK_UNDEF:
+ case LDPK_WEAKUNDEF:
+ resolution = symtab->syms[i].resolution;
+ break;
+ default:
+ assert (0);
+ }
+
+ assert (resolution != LDPR_UNKNOWN);
+
+ for (j = symtab->aux[i].next_conflict;
+ j != -1;
+ j = conflicts->aux[j].next_conflict)
+ conflicts->syms[j].resolution = resolution;
+ }
+}
+
+/* Free symbol table SYMTAB. */
+
+static void
+free_symtab (struct plugin_symtab *symtab)
+{
+ free (symtab->syms);
+ symtab->syms = NULL;
+ free (symtab->aux);
+ symtab->aux = NULL;
+}
+
/* Writes the relocations to disk. */
static void
struct plugin_file_info *info = &claimed_files[i];
struct plugin_symtab *symtab = &info->symtab;
struct ld_plugin_symbol *syms = symtab->syms;
- unsigned j;
get_symbols (info->handle, symtab->nsyms, syms);
- fprintf (f, "%s %d\n", info->name, info->symtab.nsyms);
+ finish_conflict_resolution (symtab, &info->conflicts);
- for (j = 0; j < info->symtab.nsyms; j++)
+ fprintf (f, "%s %d\n", info->name, symtab->nsyms + info->conflicts.nsyms);
+ dump_symtab (f, symtab);
+ if (info->conflicts.nsyms)
{
- uint32_t slot = symtab->slots[j];
- unsigned int resolution = syms[j].resolution;
- fprintf (f, "%d %s %s\n", slot, lto_resolution_str[resolution], syms[j].name);
+ dump_symtab (f, &info->conflicts);
+ free_symtab (&info->conflicts);
}
}
fclose (f);
return LDPS_OK;
}
-/* Callback used by gold to check if the plugin will claim FILE. Writes
- the result in CLAIMED. */
+#define SWAP(type, a, b) \
+ do { type tmp_; tmp_ = (a); (a) = (b); (b) = tmp_; } while(0)
-static enum ld_plugin_status
-claim_file_handler (const struct ld_plugin_input_file *file, int *claimed)
+/* Compare two hash table entries */
+
+static int eq_sym (const void *a, const void *b)
{
- enum ld_plugin_status status;
- Elf *elf;
- struct plugin_file_info lto_file;
- Elf_Data *symtab;
+ const struct ld_plugin_symbol *as = (const struct ld_plugin_symbol *)a;
+ const struct ld_plugin_symbol *bs = (const struct ld_plugin_symbol *)b;
- if (file->offset != 0)
- {
- char *objname;
- Elf *archive;
- off_t offset;
- /* We pass the offset of the actual file, not the archive header. */
- int t = asprintf (&objname, "%s@0x%" PRIx64, file->name,
- (int64_t) file->offset);
- check (t >= 0, LDPL_FATAL, "asprintf failed");
- lto_file.name = objname;
-
- archive = elf_begin (file->fd, ELF_C_READ, NULL);
- check (elf_kind (archive) == ELF_K_AR, LDPL_FATAL,
- "Not an archive and offset not 0");
-
- /* elf_rand expects the offset to point to the ar header, not the
- object itself. Subtract the size of the ar header (60 bytes).
- We don't uses sizeof (struct ar_hd) to avoid including ar.h */
-
- offset = file->offset - 60;
- check (offset == elf_rand (archive, offset), LDPL_FATAL,
- "could not seek in archive");
- elf = elf_begin (file->fd, ELF_C_READ, archive);
- check (elf != NULL, LDPL_FATAL, "could not find archive member");
- elf_end (archive);
- }
- else
- {
- lto_file.name = xstrdup (file->name);
- elf = elf_begin (file->fd, ELF_C_READ, NULL);
+ return !strcmp (as->name, bs->name);
+}
+
+/* Hash a symbol */
+
+static hashval_t hash_sym (const void *a)
+{
+ const struct ld_plugin_symbol *as = (const struct ld_plugin_symbol *)a;
+
+ return htab_hash_string (as->name);
+}
+
+/* Determine how strong a symbol is */
+
+static int symbol_strength (struct ld_plugin_symbol *s)
+{
+ switch (s->def)
+ {
+ case LDPK_UNDEF:
+ case LDPK_WEAKUNDEF:
+ return 0;
+ case LDPK_WEAKDEF:
+ return 1;
+ default:
+ return 2;
}
- lto_file.handle = file->handle;
+}
- *claimed = 0;
+/* In the ld -r case we can get dups in the LTO symbol tables, where
+ the same symbol can have different resolutions (e.g. undefined and defined).
- if (!elf)
- goto err;
+ We have to keep that in the LTO symbol tables, but the dups confuse
+ gold and then finally gcc by supplying incorrect resolutions.
- symtab = get_symtab (elf);
- if (!symtab)
- goto err;
+ Problem is that the main gold symbol table doesn't know about subids
+ and does not distingush the same symbols in different states.
- translate (symtab, <o_file.symtab);
+ So we drop duplicates from the linker visible symbol table
+ and keep them in a private table. Then later do own symbol
+ resolution for the duplicated based on the results for the
+ originals.
- status = add_symbols (file->handle, lto_file.symtab.nsyms,
- lto_file.symtab.syms);
- check (status == LDPS_OK, LDPL_FATAL, "could not add symbols");
+ Then when writing out the resolution file readd the dropped symbols.
+
+ XXX how to handle common? */
- *claimed = 1;
- num_claimed_files++;
- claimed_files =
- xrealloc (claimed_files,
- num_claimed_files * sizeof (struct plugin_file_info));
- claimed_files[num_claimed_files - 1] = lto_file;
+void
+resolve_conflicts (struct plugin_symtab *t, struct plugin_symtab *conflicts)
+{
+ htab_t symtab = htab_create (t->nsyms, hash_sym, eq_sym, NULL);
+ int i;
+ int out;
+ int outlen;
+
+ outlen = t->nsyms;
+ conflicts->syms = xmalloc (sizeof (struct ld_plugin_symbol) * outlen);
+ conflicts->aux = xmalloc (sizeof (struct sym_aux) * outlen);
+
+ /* Move all duplicate symbols into the auxillary conflicts table. */
+ out = 0;
+ for (i = 0; i < t->nsyms; i++)
+ {
+ struct ld_plugin_symbol *s = &t->syms[i];
+ struct sym_aux *aux = &t->aux[i];
+ void **slot;
- goto cleanup;
+ slot = htab_find_slot (symtab, s, INSERT);
+ if (*slot != NULL)
+ {
+ int cnf;
+ struct ld_plugin_symbol *orig = (struct ld_plugin_symbol *)*slot;
+ struct sym_aux *orig_aux = &t->aux[orig - t->syms];
+
+ /* Always let the linker resolve the strongest symbol */
+ if (symbol_strength (orig) < symbol_strength (s))
+ {
+ SWAP (struct ld_plugin_symbol, *orig, *s);
+ SWAP (uint32_t, orig_aux->slot, aux->slot);
+ SWAP (unsigned, orig_aux->id, aux->id);
+ /* Don't swap conflict chain pointer */
+ }
+
+ /* Move current symbol into the conflicts table */
+ cnf = conflicts->nsyms++;
+ conflicts->syms[cnf] = *s;
+ conflicts->aux[cnf] = *aux;
+ aux = &conflicts->aux[cnf];
+
+ /* Update conflicts chain of the original symbol */
+ aux->next_conflict = orig_aux->next_conflict;
+ orig_aux->next_conflict = cnf;
+
+ continue;
+ }
- err:
- free (lto_file.name);
+ /* Remove previous duplicates in the main table */
+ if (out < i)
+ {
+ t->syms[out] = *s;
+ t->aux[out] = *aux;
+ }
- cleanup:
- if (elf)
- elf_end (elf);
+ /* Put original into the hash table */
+ *slot = &t->syms[out];
+ out++;
+ }
- return LDPS_OK;
+ assert (conflicts->nsyms <= outlen);
+ assert (conflicts->nsyms + out == t->nsyms);
+
+ t->nsyms = out;
+ htab_delete (symtab);
}
/* Parse the plugin options. */
struct ld_plugin_tv *p;
enum ld_plugin_status status;
- unsigned version = elf_version (EV_CURRENT);
- check (version != EV_NONE, LDPL_FATAL, "invalid ELF version");
+ status = onload_format_checks (tv);
+ if (status != LDPS_OK)
+ return status;
p = tv;
while (p->tv_tag)
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