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/* 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

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 3, or (at your option)

any later version.

This program is distributed in the hope that it will be useful, but

WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

General Public License for more details.

You should have received a copy of the GNU General Public License

along with this program; see the file COPYING3.  If not see

<http://www.gnu.org/licenses/>.  */

/* The plugin has only one external function: onload. Gold passes it an array of

   function that the plugin uses to communicate back to gold.

   With the functions provided by gold, the plugin can be notified when

   gold first analyzes a file and pass a symbol table back to gold. The plugin

   is also notified when all symbols have been read and it is time to generate

   machine code for the necessary symbols.

   More information at http://gcc.gnu.org/wiki/whopr/driver.

   This plugin should be passed the lto-wrapper options and will forward them.

   It also has 2 options of its own:

   -debug: Print the command line used to run lto-wrapper.

   -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 <stdio.h>

#include <inttypes.h>

#include <sys/stat.h>

#include <unistd.h>

#include <fcntl.h>

#include <sys/types.h>

#ifdef HAVE_SYS_WAIT_H

#include <sys/wait.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"

/* We need to use I64 instead of ll width-specifier on native Windows.

   The reason for this is that older MS-runtimes don't support the ll.  */

#ifdef __MINGW32__

#define PRI_LL "I64"

#else

#define PRI_LL "ll"

#endif

/* 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

/* 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.

   The id must be 64bit to minimze collisions. */

struct sym_aux

{

  uint32_t slot;

  unsigned long long id;

  unsigned next_conflict;

};

struct plugin_symtab

{

  int nsyms;

  struct sym_aux *aux;

  struct ld_plugin_symbol *syms;

  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. */

struct plugin_file_info

{

  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_register_all_symbols_read register_all_symbols_read;

static ld_plugin_get_symbols get_symbols, get_symbols_v2;

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 **output_files = NULL;

static unsigned int num_output_files = 0;

static char **lto_wrapper_argv;

static int lto_wrapper_num_args;

static char **pass_through_items = NULL;

static unsigned int num_pass_through_items;

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_1 (int gate, enum ld_plugin_level level, const char *text)

{

  if (gate)

    return;

  if (message)

    message (level, text);

  else

    {

      /* If there is no nicer way to inform the user, fallback to stderr. */

      fprintf (stderr, "%s\n", text);

      if (level == LDPL_FATAL)

        abort ();

    }

}

/* 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. */

static 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[] =

    {

      LDPK_DEF,

      LDPK_WEAKDEF,

      LDPK_UNDEF,

      LDPK_WEAKUNDEF,

      LDPK_COMMON

    };

  enum ld_plugin_symbol_visibility translate_visibility[] =

    {

      LDPV_DEFAULT,

      LDPV_PROTECTED,

      LDPV_INTERNAL,

      LDPV_HIDDEN

    };

  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->version = NULL;

  entry->comdat_key = p;

  while (*p)

    p++;

  p++;

  if (strlen (entry->comdat_key) == 0)

    entry->comdat_key = NULL;

  else

    entry->comdat_key = xstrdup (entry->comdat_key);

  t = *p;

  check (t <= 4, LDPL_FATAL, "invalid symbol kind found");

  entry->def = translate_kind[t];

  p++;

  t = *p;

  check (t <= 3, LDPL_FATAL, "invalid symbol visibility found");

  entry->visibility = translate_visibility[t];

  p++;

  memcpy (&entry->size, p, sizeof (uint64_t));

  p += 8;

  memcpy (&aux->slot, p, sizeof (uint32_t));

  p += 4;

  entry->resolution = LDPR_UNKNOWN;

  aux->next_conflict = -1;

  return p;

}

/* Translate the IL symbol table located between DATA and END. Append the

   slots and symbols to OUT. */

static void

translate (char *data, char *end, struct plugin_symtab *out)

{

  struct sym_aux *aux;

  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;

}

/* Free all memory that is no longer needed after writing the symbol

   resolution. */

static void

free_1 (void)

{

  unsigned int i;

  for (i = 0; i < num_claimed_files; i++)

    {

      struct plugin_file_info *info = &claimed_files[i];

      struct plugin_symtab *symtab = &info->symtab;

      unsigned int j;

      for (j = 0; j < symtab->nsyms; j++)

        {

          struct ld_plugin_symbol *s = &symtab->syms[j];

          free (s->name);

          free (s->comdat_key);

        }

      free (symtab->syms);

      symtab->syms = NULL;

    }

}

/* Free all remaining memory. */

static void

free_2 (void)

{

  unsigned int i;

  for (i = 0; i < num_claimed_files; i++)

    {

      struct plugin_file_info *info = &claimed_files[i];

      struct plugin_symtab *symtab = &info->symtab;

      free (symtab->aux);

      free (info->name);

    }

  for (i = 0; i < num_output_files; i++)

    free (output_files[i]);

  free (output_files);

  free (claimed_files);

  claimed_files = NULL;

  num_claimed_files = 0;

  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 %" PRI_LL "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

write_resolution (void)

{

  unsigned int i;

  FILE *f;

  check (resolution_file, LDPL_FATAL, "resolution file not specified");

  f = fopen (resolution_file, "w");

  check (f, LDPL_FATAL, "could not open file");

  fprintf (f, "%d\n", num_claimed_files);

  for (i = 0; i < num_claimed_files; i++)

    {

      struct plugin_file_info *info = &claimed_files[i];

      struct plugin_symtab *symtab = &info->symtab;

      struct ld_plugin_symbol *syms = symtab->syms;

      /* Version 2 of API supports IRONLY_EXP resolution that is

         accepted by GCC-4.7 and newer.  */

      if (get_symbols_v2)

        get_symbols_v2 (info->handle, symtab->nsyms, syms);

      else

        get_symbols (info->handle, symtab->nsyms, syms);

      finish_conflict_resolution (symtab, &info->conflicts);

      fprintf (f, "%s %d\n", info->name, symtab->nsyms + info->conflicts.nsyms);

      dump_symtab (f, symtab);

      if (info->conflicts.nsyms)

        {

          dump_symtab (f, &info->conflicts);

          free_symtab (&info->conflicts);

        }

    }

  fclose (f);

}

/* Pass files generated by the lto-wrapper to the linker. FD is lto-wrapper's

   stdout. */

static void

add_output_files (FILE *f)

{

  for (;;)

    {

      const unsigned piece = 32;

      char *buf, *s = xmalloc (piece);

      size_t len;

      buf = s;

cont:

      if (!fgets (buf, piece, f))

        {

          free (s);

          break;

        }

      len = strlen (s);

      if (s[len - 1] != '\n')

        {

          s = xrealloc (s, len + piece);

          buf = s + len;

          goto cont;

        }

      s[len - 1] = '\0';

      num_output_files++;

      output_files

        = xrealloc (output_files, num_output_files * sizeof (char *));

      output_files[num_output_files - 1] = s;

      add_input_file (output_files[num_output_files - 1]);

    }

}

/* Execute the lto-wrapper. ARGV[0] is the binary. The rest of ARGV is the

   argument list. */

static void

exec_lto_wrapper (char *argv[])

{

  int t, i;

  int status;

  char *at_args;

  FILE *args;

  FILE *wrapper_output;

  char *new_argv[3];

  struct pex_obj *pex;

  const char *errmsg;

  /* Write argv to a file to avoid a command line that is too long. */

  arguments_file_name = make_temp_file ("");

  check (arguments_file_name, LDPL_FATAL,

         "Failed to generate a temorary file name");

  args = fopen (arguments_file_name, "w");

  check (args, LDPL_FATAL, "could not open arguments file");

  t = writeargv (&argv[1], args);

  check (t == 0, LDPL_FATAL, "could not write arguments");

  t = fclose (args);

  check (t == 0, LDPL_FATAL, "could not close arguments file");

  at_args = concat ("@", arguments_file_name, NULL);

  check (at_args, LDPL_FATAL, "could not allocate");

  for (i = 1; argv[i]; i++)

    {

      char *a = argv[i];

      if (a[0] == '-' && a[1] == 'v' && a[2] == '\0')

        {

          for (i = 0; argv[i]; i++)

            fprintf (stderr, "%s ", argv[i]);

          fprintf (stderr, "\n");

          break;

        }

    }

  new_argv[0] = argv[0];

  new_argv[1] = at_args;

  new_argv[2] = NULL;

  if (debug)

    {

      for (i = 0; new_argv[i]; i++)

        fprintf (stderr, "%s ", new_argv[i]);

      fprintf (stderr, "\n");

    }

  pex = pex_init (PEX_USE_PIPES, "lto-wrapper", NULL);

  check (pex != NULL, LDPL_FATAL, "could not pex_init lto-wrapper");

  errmsg = pex_run (pex, 0, new_argv[0], new_argv, NULL, NULL, &t);

  check (errmsg == NULL, LDPL_FATAL, "could not run lto-wrapper");

  check (t == 0, LDPL_FATAL, "could not run lto-wrapper");

  wrapper_output = pex_read_output (pex, 0);

  check (wrapper_output, LDPL_FATAL, "could not read lto-wrapper output");

  add_output_files (wrapper_output);

  t = pex_get_status (pex, 1, &status);

  check (t == 1, LDPL_FATAL, "could not get lto-wrapper exit status");

  check (WIFEXITED (status) && WEXITSTATUS (status) == 0, LDPL_FATAL,

         "lto-wrapper failed");

  pex_free (pex);

  free (at_args);

}

/* Pass the original files back to the linker. */

static void

use_original_files (void)

{

  unsigned i;

  for (i = 0; i < num_claimed_files; i++)

    {

      struct plugin_file_info *info = &claimed_files[i];

      add_input_file (info->name);

    }

}

/* Called by the linker once all symbols have been read. */

static enum ld_plugin_status

all_symbols_read_handler (void)

{

  unsigned i;

  unsigned num_lto_args = num_claimed_files + lto_wrapper_num_args + 1;

  char **lto_argv;

  const char **lto_arg_ptr;

  if (num_claimed_files == 0)

    return LDPS_OK;

  if (nop)

    {

      use_original_files ();

      return LDPS_OK;

    }

  lto_argv = (char **) xcalloc (sizeof (char *), num_lto_args);

  lto_arg_ptr = (const char **) lto_argv;

  assert (lto_wrapper_argv);

  write_resolution ();

  free_1 ();

  for (i = 0; i < lto_wrapper_num_args; i++)

    *lto_arg_ptr++ = lto_wrapper_argv[i];

  for (i = 0; i < num_claimed_files; i++)

    {

      struct plugin_file_info *info = &claimed_files[i];

      *lto_arg_ptr++ = info->name;

    }

  *lto_arg_ptr++ = NULL;

  exec_lto_wrapper (lto_argv);

  free (lto_argv);

  /* --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++)

        {

          if (strncmp (pass_through_items[i], "-l", 2) == 0)

            add_input_library (pass_through_items[i] + 2);

          else

            add_input_file (pass_through_items[i]);

          free (pass_through_items[i]);

          pass_through_items[i] = NULL;

        }

      free (pass_through_items);

      pass_through_items = NULL;

    }

  return LDPS_OK;

}

/* Remove temporary files at the end of the link. */

static enum ld_plugin_status

cleanup_handler (void)

{

  unsigned int i;

  int t;

  if (debug)

    return LDPS_OK;

  if (arguments_file_name)

    {

      t = unlink (arguments_file_name);

      check (t == 0, LDPL_FATAL, "could not unlink arguments file");

    }

  for (i = 0; i < num_output_files; i++)

    {

      t = unlink (output_files[i]);

      check (t == 0, LDPL_FATAL, "could not unlink output file");

    }

  free_2 ();

  return LDPS_OK;

}