#include <sys/wait.h>
#include <stdbool.h>
#include <libiberty.h>
+#include <hashtab.h>
/* The presence of gelf.h is checked by the toplevel configure script. */
#include <gelf.h>
must keep SYMS until all_symbols_read is called to give the linker time to
copy the symbol information. */
+struct sym_aux
+{
+ uint32_t slot;
+ unsigned id;
+ unsigned next_conflict;
+};
+
struct plugin_symtab
{
int nsyms;
- uint32_t *slots;
+ struct sym_aux *aux;
struct ld_plugin_symbol *syms;
+ unsigned id;
};
/* All that we have to remember about a file. */
char *name;
void *handle;
struct plugin_symtab symtab;
+ struct plugin_symtab conflicts;
};
Returns the address of the next entry. */
static char *
-parse_table_entry (char *p, struct ld_plugin_symbol *entry, uint32_t *slot)
+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;
+ aux->next_conflict = -1;
+
return p;
}
-/* Return the section in ELF that is named NAME. */
+#define LTO_SECTION_PREFIX ".gnu.lto_.symtab"
-static Elf_Scn *
-get_section (Elf *elf, const char *name)
+/* Translate the IL symbol table SYMTAB. Append the slots and symbols to OUT. */
+
+static void
+translate (Elf_Data *symtab, struct plugin_symtab *out)
{
+ struct sym_aux *aux;
+ char *data = symtab->d_buf;
+ char *end = data + symtab->d_size;
+ struct ld_plugin_symbol *syms = NULL;
+ 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->aux = aux;
+}
+
+/* Process all lto symtabs of file ELF. */
+
+static int
+process_symtab (Elf *elf, struct plugin_symtab *out)
+{
+ int found = 0;
Elf_Scn *section = 0;
GElf_Ehdr header;
GElf_Ehdr *t = gelf_getehdr (elf, &header);
if (t == NULL)
- return NULL;
+ return 0;
assert (t == &header);
while ((section = elf_nextscn(elf, section)) != 0)
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;
-}
-
-/* Returns the IL symbol table of file ELF. */
-
-static Elf_Data *
-get_symtab (Elf *elf)
-{
- 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 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]);
+ if (strncmp (t, LTO_SECTION_PREFIX, strlen (LTO_SECTION_PREFIX)) == 0)
+ {
+ char *s = strrchr (t, '.');
+ if (s)
+ sscanf (s, ".%x", &out->id);
+ translate (elf_getdata (section, NULL), out);
+ found++;
+ }
}
-
- out->nsyms = n;
- out->syms = syms;
- out->slots = slots;
+ return found;
}
/* 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, "%d %x %s %s\n", 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;
+
+ 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;
}
+#define SWAP(type, a, b) \
+ do { type tmp_; tmp_ = (a); (a) = (b); (b) = tmp_; } while(0)
+
+/* Compare two hash table entries */
+
+static int eq_sym (const void *a, const void *b)
+{
+ const struct ld_plugin_symbol *as = (const struct ld_plugin_symbol *)a;
+ const struct ld_plugin_symbol *bs = (const struct ld_plugin_symbol *)b;
+
+ 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;
+ }
+}
+
+/* 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).
+
+ We have to keep that in the LTO symbol tables, but the dups confuse
+ gold and then finally gcc by supplying incorrect resolutions.
+
+ Problem is that the main gold symbol table doesn't know about subids
+ and does not distingush the same symbols in different states.
+
+ 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.
+
+ Then when writing out the resolution file readd the dropped symbols.
+
+ XXX how to handle common? */
+
+static 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;
+
+ 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;
+ }
+
+ /* Remove previous duplicates in the main table */
+ if (out < i)
+ {
+ t->syms[out] = *s;
+ t->aux[out] = *aux;
+ }
+
+ /* Put original into the hash table */
+ *slot = &t->syms[out];
+ out++;
+ }
+
+ assert (conflicts->nsyms <= outlen);
+ assert (conflicts->nsyms + out == t->nsyms);
+
+ t->nsyms = out;
+ htab_delete (symtab);
+}
+
/* Callback used by gold to check if the plugin will claim FILE. Writes
the result in CLAIMED. */
enum ld_plugin_status status;
Elf *elf;
struct plugin_file_info lto_file;
- Elf_Data *symtab;
+ int n;
+
+ memset (<o_file, 0, sizeof (struct plugin_file_info));
if (file->offset != 0)
{
if (!elf)
goto err;
- symtab = get_symtab (elf);
- if (!symtab)
+ n = process_symtab (elf, <o_file.symtab);
+ if (n == 0)
goto err;
- translate (symtab, <o_file.symtab);
+ if (n > 1)
+ resolve_conflicts (<o_file.symtab, <o_file.conflicts);
status = add_symbols (file->handle, lto_file.symtab.nsyms,
lto_file.symtab.syms);
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