-/* 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
-nop: Instead of running lto-wrapper, pass the original to the plugin. This
only works if the input files are hybrid. */
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+#if HAVE_STDINT_H
+#include <stdint.h>
+#endif
#include <assert.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
+#ifdef HAVE_SYS_WAIT_H
#include <sys/wait.h>
-#include <stdbool.h>
+#endif
+#ifndef WIFEXITED
+#define WIFEXITED(S) (((S) & 0xff) == 0)
+#endif
+#ifndef WEXITSTATUS
+#define WEXITSTATUS(S) (((S) & 0xff00) >> 8)
+#endif
#include <libiberty.h>
+#include <hashtab.h>
+#include "../gcc/lto/common.h"
+#include "simple-object.h"
+#include "plugin-api.h"
-/* The presence of gelf.h is checked by the toplevel configure script. */
-#include <gelf.h>
+/* Handle opening elf files on hosts, such as Windows, that may use
+ text file handling that will break binary access. */
+#ifndef O_BINARY
+# define O_BINARY 0
+#endif
-#include "plugin-api.h"
-#include "../gcc/lto/common.h"
+/* Segment name for LTO sections. This is only used for Mach-O.
+ FIXME: This needs to be kept in sync with darwin.c. */
+
+#define LTO_SEGMENT_NAME "__GNU_LTO"
+
+/* LTO magic section name. */
+
+#define LTO_SECTION_PREFIX ".gnu.lto_.symtab"
+#define LTO_SECTION_PREFIX_LEN (sizeof (LTO_SECTION_PREFIX) - 1)
/* 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. */
+ copy the symbol information.
+ The id must be 64bit to minimze collisions. */
struct sym_aux
{
uint32_t slot;
- unsigned id;
+ unsigned long long id;
+ unsigned next_conflict;
};
struct plugin_symtab
int nsyms;
struct sym_aux *aux;
struct ld_plugin_symbol *syms;
- unsigned id;
+ unsigned long long id;
+};
+
+/* Encapsulates object file data during symbol scan. */
+struct plugin_objfile
+{
+ int found;
+ simple_object_read *objfile;
+ struct plugin_symtab *out;
+ const struct ld_plugin_input_file *file;
};
/* All that we have to remember about a file. */
char *name;
void *handle;
struct plugin_symtab symtab;
+ struct plugin_symtab conflicts;
};
+/* Until ASM_OUTPUT_LABELREF can be hookized and decoupled from
+ stdio file streams, we do simple label translation here. */
+
+enum symbol_style
+{
+ ss_none, /* No underscore prefix. */
+ ss_win32, /* Underscore prefix any symbol not beginning with '@'. */
+ ss_uscore, /* Underscore prefix all symbols. */
+};
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_file add_input_file;
static ld_plugin_add_input_library add_input_library;
static ld_plugin_message message;
+static ld_plugin_add_symbols add_symbols;
static struct plugin_file_info *claimed_files = NULL;
static unsigned int num_claimed_files = 0;
static char **pass_through_items = NULL;
static unsigned int num_pass_through_items;
-static bool debug;
-static bool nop;
+static char debug;
+static char nop;
static char *resolution_file = NULL;
+/* The version of gold being used, or -1 if not gold. The number is
+ MAJOR * 100 + MINOR. */
+static int gold_version = -1;
+
+/* Not used by default, but can be overridden at runtime
+ by using -plugin-opt=-sym-style={none,win32,underscore|uscore}
+ (in fact, only first letter of style arg is checked.) */
+static enum symbol_style sym_style = ss_none;
+
static void
-check (bool gate, enum ld_plugin_level level, const char *text)
+check_1 (int gate, enum ld_plugin_level level, const char *text)
{
if (gate)
return;
}
}
+/* This little wrapper allows check to be called with a non-integer
+ first argument, such as a pointer that must be non-NULL. We can't
+ use c99 bool type to coerce it into range, so we explicitly test. */
+#define check(GATE, LEVEL, TEXT) check_1 (((GATE) != 0), (LEVEL), (TEXT))
+
/* Parse an entry of the IL symbol table. The data to be parsed is pointed
by P and the result is written in ENTRY. The slot number is stored in SLOT.
Returns the address of the next entry. */
LDPV_HIDDEN
};
- entry->name = xstrdup (p);
+ switch (sym_style)
+ {
+ case ss_win32:
+ if (p[0] == '@')
+ {
+ /* cf. Duff's device. */
+ case ss_none:
+ entry->name = xstrdup (p);
+ break;
+ }
+ /* FALL-THROUGH. */
+ case ss_uscore:
+ entry->name = concat ("_", p, NULL);
+ break;
+ default:
+ check (0, LDPL_FATAL, "invalid symbol style requested");
+ break;
+ }
while (*p)
p++;
p++;
entry->visibility = translate_visibility[t];
p++;
- entry->size = *(uint64_t *) p;
+ memcpy (&entry->size, p, sizeof (uint64_t));
p += 8;
- aux->slot = *(uint32_t *) p;
+ memcpy (&aux->slot, p, sizeof (uint32_t));
p += 4;
entry->resolution = LDPR_UNKNOWN;
+ aux->next_conflict = -1;
+
return p;
}
-#define LTO_SECTION_PREFIX ".gnu.lto_.symtab"
-
-/* Translate the IL symbol table SYMTAB. Append the slots and symbols to OUT. */
+/* Translate the IL symbol table located between DATA and END. Append the
+ slots and symbols to OUT. */
static void
-translate (Elf_Data *symtab, struct plugin_symtab *out)
+translate (char *data, char *end, 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;
data = parse_table_entry (data, &syms[n], &aux[n]);
}
- fprintf (stderr, "n = %d len = %d end-data=%lu\n", n, len, end-data);
assert(n < len);
out->nsyms = n;
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 0;
- 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 (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 = 1;
- }
- }
- return found;
-}
-
/* Free all memory that is no longer needed after writing the symbol
resolution. */
{
struct ld_plugin_symbol *s = &symtab->syms[j];
free (s->name);
- if (s->comdat_key)
- free (s->comdat_key);
+ free (s->comdat_key);
}
free (symtab->syms);
symtab->syms = NULL;
claimed_files = NULL;
num_claimed_files = 0;
- if (arguments_file_name)
- free (arguments_file_name);
+ free (arguments_file_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 %llx %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->aux[j].slot;
- unsigned int resolution = syms[j].resolution;
- fprintf (f, "%d %x %s %s\n", slot, symtab->aux[j].id,
- lto_resolution_str[resolution], syms[j].name);
+ dump_symtab (f, &info->conflicts);
+ free_symtab (&info->conflicts);
}
}
fclose (f);
buf = s;
cont:
if (!fgets (buf, piece, f))
- break;
+ {
+ free (s);
+ break;
+ }
len = strlen (s);
if (s[len - 1] != '\n')
{
free (lto_argv);
- if (pass_through_items)
+ /* --pass-through is not needed when using gold 1.11 or later. */
+ if (pass_through_items && gold_version < 111)
{
unsigned int i;
for (i = 0; i < num_pass_through_items; i++)
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 long long, 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);
+}
+
+/* Process one section of an object file. */
+
+static int
+process_symtab (void *data, const char *name, off_t offset, off_t length)
+{
+ struct plugin_objfile *obj = (struct plugin_objfile *)data;
+ char *s;
+ char *secdata;
+
+ if (strncmp (name, LTO_SECTION_PREFIX, LTO_SECTION_PREFIX_LEN) != 0)
+ return 1;
+
+ s = strrchr (name, '.');
+ if (s)
+ sscanf (s, ".%llx", &obj->out->id);
+ secdata = xmalloc (length);
+ offset += obj->file->offset;
+ if (offset != lseek (obj->file->fd, offset, SEEK_SET)
+ || length != read (obj->file->fd, secdata, length))
+ {
+ if (message)
+ message (LDPL_FATAL, "%s: corrupt object file", obj->file->name);
+ /* Force claim_file_handler to abandon this file. */
+ obj->found = 0;
+ free (secdata);
+ return 0;
+ }
+
+ translate (secdata, secdata + length, obj->out);
+ obj->found++;
+ free (secdata);
+ return 1;
+}
+
/* Callback used by gold to check if the plugin will claim FILE. Writes
the result in CLAIMED. */
claim_file_handler (const struct ld_plugin_input_file *file, int *claimed)
{
enum ld_plugin_status status;
- Elf *elf;
+ struct plugin_objfile obj;
struct plugin_file_info lto_file;
+ int err;
+ const char *errmsg;
memset (<o_file, 0, sizeof (struct plugin_file_info));
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);
+ /* We pass the offset of the actual file, not the archive header.
+ Can't use PRIx64, because that's C99, so we have to print the
+ 64-bit hex int as two 32-bit ones. */
+ int lo, hi, t;
+ lo = file->offset & 0xffffffff;
+ hi = ((int64_t)file->offset >> 32) & 0xffffffff;
+ t = hi ? asprintf (&objname, "%s@0x%x%08x", file->name, lo, hi)
+ : asprintf (&objname, "%s@0x%x", file->name, lo);
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);
}
lto_file.handle = file->handle;
*claimed = 0;
+ obj.file = file;
+ obj.found = 0;
+ obj.out = <o_file.symtab;
+ errmsg = NULL;
+ obj.objfile = simple_object_start_read (file->fd, file->offset, LTO_SEGMENT_NAME,
+ &errmsg, &err);
+ /* No file, but also no error code means unrecognized format; just skip it. */
+ if (!obj.objfile && !err)
+ goto err;
+
+ if (obj.objfile)
+ errmsg = simple_object_find_sections (obj.objfile, process_symtab, &obj, &err);
+
+ if (!obj.objfile || errmsg)
+ {
+ if (err && message)
+ message (LDPL_FATAL, "%s: %s: %s", file->name, errmsg,
+ xstrerror (err));
+ else if (message)
+ message (LDPL_FATAL, "%s: %s", file->name, errmsg);
+ goto err;
+ }
- if (!elf || !process_symtab (elf, <o_file.symtab))
+ if (obj.found == 0)
goto err;
+ if (obj.found > 1)
+ resolve_conflicts (<o_file.symtab, <o_file.conflicts);
+
status = add_symbols (file->handle, lto_file.symtab.nsyms,
lto_file.symtab.syms);
check (status == LDPS_OK, LDPL_FATAL, "could not add symbols");
free (lto_file.name);
cleanup:
- if (elf)
- elf_end (elf);
+ if (obj.objfile)
+ simple_object_release_read (obj.objfile);
return LDPS_OK;
}
pass_through_items[num_pass_through_items - 1] =
xstrdup (option + strlen ("-pass-through="));
}
+ else if (!strncmp (option, "-sym-style=", sizeof ("-sym-style=") - 1))
+ {
+ switch (option[sizeof ("-sym-style=") - 1])
+ {
+ case 'w':
+ sym_style = ss_win32;
+ break;
+ case 'u':
+ sym_style = ss_uscore;
+ break;
+ default:
+ sym_style = ss_none;
+ break;
+ }
+ }
else
{
int size;
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");
-
p = tv;
while (p->tv_tag)
{
case LDPT_OPTION:
process_option (p->tv_u.tv_string);
break;
+ case LDPT_GOLD_VERSION:
+ gold_version = p->tv_u.tv_val;
+ break;
default:
break;
}