path: root/gcc/lto-streamer.c

/* Miscellaneous utilities for GIMPLE streaming.  Things that are used
   in both input and output are here.

   Copyright 2009, 2010 Free Software Foundation, Inc.
   Contributed by Doug Kwan <dougkwan@google.com>

This file is part of GCC.

GCC 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.

GCC 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 GCC; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "toplev.h"
#include "flags.h"
#include "tree.h"
#include "gimple.h"
#include "tree-flow.h"
#include "diagnostic-core.h"
#include "bitmap.h"
#include "vec.h"
#include "lto-streamer.h"

/* Statistics gathered during LTO, WPA and LTRANS.  */
struct lto_stats_d lto_stats;

/* LTO uses bitmaps with different life-times.  So use a seperate
   obstack for all LTO bitmaps.  */
static bitmap_obstack lto_obstack;
static bool lto_obstack_initialized;


/* Return a string representing LTO tag TAG.  */

const char *
lto_tag_name (enum LTO_tags tag)
{
  if (lto_tag_is_tree_code_p (tag))
    {
      /* For tags representing tree nodes, return the name of the
	 associated tree code.  */
      return tree_code_name[lto_tag_to_tree_code (tag)];
    }

  if (lto_tag_is_gimple_code_p (tag))
    {
      /* For tags representing gimple statements, return the name of
	 the associated gimple code.  */
      return gimple_code_name[lto_tag_to_gimple_code (tag)];
    }

  switch (tag)
    {
    case LTO_null:
      return "LTO_null";
    case LTO_bb0:
      return "LTO_bb0";
    case LTO_bb1:
      return "LTO_bb1";
    case LTO_eh_region:
      return "LTO_eh_region";
    case LTO_function:
      return "LTO_function";
    case LTO_eh_table:
      return "LTO_eh_table";
    case LTO_ert_cleanup:
      return "LTO_ert_cleanup";
    case LTO_ert_try:
      return "LTO_ert_try";
    case LTO_ert_allowed_exceptions:
      return "LTO_ert_allowed_exceptions";
    case LTO_ert_must_not_throw:
      return "LTO_ert_must_not_throw";
    case LTO_tree_pickle_reference:
      return "LTO_tree_pickle_reference";
    case LTO_field_decl_ref:
      return "LTO_field_decl_ref";
    case LTO_function_decl_ref:
      return "LTO_function_decl_ref";
    case LTO_label_decl_ref:
      return "LTO_label_decl_ref";
    case LTO_namespace_decl_ref:
      return "LTO_namespace_decl_ref";
    case LTO_result_decl_ref:
      return "LTO_result_decl_ref";
    case LTO_ssa_name_ref:
      return "LTO_ssa_name_ref";
    case LTO_type_decl_ref:
      return "LTO_type_decl_ref";
    case LTO_type_ref:
      return "LTO_type_ref";
    case LTO_global_decl_ref:
      return "LTO_global_decl_ref";
    default:
      return "LTO_UNKNOWN";
    }
}


/* Allocate a bitmap from heap.  Initializes the LTO obstack if necessary.  */

bitmap
lto_bitmap_alloc (void)
{
  if (!lto_obstack_initialized)
    {
      bitmap_obstack_initialize (&lto_obstack);
      lto_obstack_initialized = true;
    }
  return BITMAP_ALLOC (&lto_obstack);
}

/* Free bitmap B.  */

void
lto_bitmap_free (bitmap b)
{
  BITMAP_FREE (b);
}


/* Get a section name for a particular type or name.  The NAME field
   is only used if SECTION_TYPE is LTO_section_function_body. For all
   others it is ignored.  The callee of this function is responsible
   to free the returned name.  */

char *
lto_get_section_name (int section_type, const char *name, struct lto_file_decl_data *f)
{
  const char *add;
  char post[32];
  const char *sep;

  if (section_type == LTO_section_function_body)
    {
      gcc_assert (name != NULL);
      if (name[0] == '*')
	name++;
      add = name;
      sep = "";
    }
  else if (section_type < LTO_N_SECTION_TYPES)
    {
      add = lto_section_name[section_type];
      sep = ".";
    }
  else
    internal_error ("bytecode stream: unexpected LTO section %s", name);

  /* Make the section name unique so that ld -r combining sections
     doesn't confuse the reader with merged sections.

     For options don't add a ID, the option reader cannot deal with them
     and merging should be ok here.

     XXX: use crc64 to minimize collisions? */
  if (section_type == LTO_section_opts)
    strcpy (post, "");
  else
    sprintf (post, ".%x", f ? f->id : crc32_string(0, get_random_seed (false)));
  return concat (LTO_SECTION_NAME_PREFIX, sep, add, post, NULL);
}


/* Show various memory usage statistics related to LTO.  */

void
print_lto_report (void)
{
  const char *s = (flag_lto) ? "LTO" : (flag_wpa) ? "WPA" : "LTRANS";
  unsigned i;

  fprintf (stderr, "%s statistics\n", s);
  fprintf (stderr, "[%s] # of input files: "
	   HOST_WIDE_INT_PRINT_UNSIGNED "\n", s, lto_stats.num_input_files);

  fprintf (stderr, "[%s] # of input cgraph nodes: "
	   HOST_WIDE_INT_PRINT_UNSIGNED "\n", s,
	   lto_stats.num_input_cgraph_nodes);

  fprintf (stderr, "[%s] # of function bodies: "
	   HOST_WIDE_INT_PRINT_UNSIGNED "\n", s,
	   lto_stats.num_function_bodies);

  fprintf (stderr, "[%s] ", s);
  print_gimple_types_stats ();

  for (i = 0; i < NUM_TREE_CODES; i++)
    if (lto_stats.num_trees[i])
      fprintf (stderr, "[%s] # of '%s' objects read: "
	       HOST_WIDE_INT_PRINT_UNSIGNED "\n", s,
	       tree_code_name[i], lto_stats.num_trees[i]);

  if (flag_lto)
    {
      fprintf (stderr, "[%s] Compression: "
	       HOST_WIDE_INT_PRINT_UNSIGNED " output bytes, "
	       HOST_WIDE_INT_PRINT_UNSIGNED " compressed bytes", s,
	       lto_stats.num_output_il_bytes,
	       lto_stats.num_compressed_il_bytes);
      if (lto_stats.num_output_il_bytes > 0)
	{
	  const float dividend = (float) lto_stats.num_compressed_il_bytes;
	  const float divisor = (float) lto_stats.num_output_il_bytes;
	  fprintf (stderr, " (ratio: %f)", dividend / divisor);
	}
      fprintf (stderr, "\n");
    }

  if (flag_wpa)
    {
      fprintf (stderr, "[%s] # of output files: "
	       HOST_WIDE_INT_PRINT_UNSIGNED "\n", s,
	       lto_stats.num_output_files);

      fprintf (stderr, "[%s] # of output cgraph nodes: "
	       HOST_WIDE_INT_PRINT_UNSIGNED "\n", s,
	       lto_stats.num_output_cgraph_nodes);

      fprintf (stderr, "[%s] # callgraph partitions: "
	       HOST_WIDE_INT_PRINT_UNSIGNED "\n", s,
	       lto_stats.num_cgraph_partitions);

      fprintf (stderr, "[%s] Compression: "
	       HOST_WIDE_INT_PRINT_UNSIGNED " input bytes, "
	       HOST_WIDE_INT_PRINT_UNSIGNED " uncompressed bytes", s,
	       lto_stats.num_input_il_bytes,
	       lto_stats.num_uncompressed_il_bytes);
      if (lto_stats.num_input_il_bytes > 0)
	{
	  const float dividend = (float) lto_stats.num_uncompressed_il_bytes;
	  const float divisor = (float) lto_stats.num_input_il_bytes;
	  fprintf (stderr, " (ratio: %f)", dividend / divisor);
	}
      fprintf (stderr, "\n");
    }

  for (i = 0; i < LTO_N_SECTION_TYPES; i++)
    fprintf (stderr, "[%s] Size of mmap'd section %s: "
	     HOST_WIDE_INT_PRINT_UNSIGNED " bytes\n", s,
	     lto_section_name[i], lto_stats.section_size[i]);
}


/* Check that all the TS_* structures handled by the lto_output_* and
   lto_input_* routines are exactly ALL the structures defined in
   treestruct.def.  */

static void
check_handled_ts_structures (void)
{
  bool handled_p[LAST_TS_ENUM];
  unsigned i;

  memset (&handled_p, 0, sizeof (handled_p));

  /* These are the TS_* structures that are either handled or
     explicitly ignored by the streamer routines.  */
  handled_p[TS_BASE] = true;
  handled_p[TS_TYPED] = true;
  handled_p[TS_COMMON] = true;
  handled_p[TS_INT_CST] = true;
  handled_p[TS_REAL_CST] = true;
  handled_p[TS_FIXED_CST] = true;
  handled_p[TS_VECTOR] = true;
  handled_p[TS_STRING] = true;
  handled_p[TS_COMPLEX] = true;
  handled_p[TS_IDENTIFIER] = true;
  handled_p[TS_DECL_MINIMAL] = true;
  handled_p[TS_DECL_COMMON] = true;
  handled_p[TS_DECL_WRTL] = true;
  handled_p[TS_DECL_NON_COMMON] = true;
  handled_p[TS_DECL_WITH_VIS] = true;
  handled_p[TS_FIELD_DECL] = true;
  handled_p[TS_VAR_DECL] = true;
  handled_p[TS_PARM_DECL] = true;
  handled_p[TS_LABEL_DECL] = true;
  handled_p[TS_RESULT_DECL] = true;
  handled_p[TS_CONST_DECL] = true;
  handled_p[TS_TYPE_DECL] = true;
  handled_p[TS_FUNCTION_DECL] = true;
  handled_p[TS_TYPE] = true;
  handled_p[TS_LIST] = true;
  handled_p[TS_VEC] = true;
  handled_p[TS_EXP] = true;
  handled_p[TS_SSA_NAME] = true;
  handled_p[TS_BLOCK] = true;
  handled_p[TS_BINFO] = true;
  handled_p[TS_STATEMENT_LIST] = true;
  handled_p[TS_CONSTRUCTOR] = true;
  handled_p[TS_OMP_CLAUSE] = true;
  handled_p[TS_OPTIMIZATION] = true;
  handled_p[TS_TARGET_OPTION] = true;
  handled_p[TS_TRANSLATION_UNIT_DECL] = true;

  /* Anything not marked above will trigger the following assertion.
     If this assertion triggers, it means that there is a new TS_*
     structure that should be handled by the streamer.  */
  for (i = 0; i < LAST_TS_ENUM; i++)
    gcc_assert (handled_p[i]);
}


/* Helper for lto_streamer_cache_insert_1.  Add T to CACHE->NODES at
   slot IX.  */

static void
lto_streamer_cache_add_to_node_array (struct lto_streamer_cache_d *cache,
				      unsigned ix, tree t)
{
  /* Make sure we're either replacing an old element or
     appending consecutively.  */
  gcc_assert (ix <= VEC_length (tree, cache->nodes));

  if (ix == VEC_length (tree, cache->nodes))
    VEC_safe_push (tree, heap, cache->nodes, t);
  else
    VEC_replace (tree, cache->nodes, ix, t);
}


/* Helper for lto_streamer_cache_insert and lto_streamer_cache_insert_at.
   CACHE, T, and IX_P are as in lto_streamer_cache_insert.

   If INSERT_AT_NEXT_SLOT_P is true, T is inserted at the next available
   slot in the cache.  Otherwise, T is inserted at the position indicated
   in *IX_P.

   If T already existed in CACHE, return true.  Otherwise,
   return false.  */

static bool
lto_streamer_cache_insert_1 (struct lto_streamer_cache_d *cache,
			     tree t, unsigned *ix_p,
			     bool insert_at_next_slot_p)
{
  void **slot;
  unsigned ix;
  bool existed_p;

  gcc_assert (t);

  slot = pointer_map_insert (cache->node_map, t);
  if (!*slot)
    {
      /* Determine the next slot to use in the cache.  */
      if (insert_at_next_slot_p)
	ix = VEC_length (tree, cache->nodes);
      else
	ix = *ix_p;
       *slot = (void *)(size_t) (ix + 1);

      lto_streamer_cache_add_to_node_array (cache, ix, t);

      /* Indicate that the item was not present in the cache.  */
      existed_p = false;
    }
  else
    {
      ix = (size_t) *slot - 1;

      if (!insert_at_next_slot_p && ix != *ix_p)
	{
	  /* If the caller wants to insert T at a specific slot
	     location, and ENTRY->TO does not match *IX_P, add T to
	     the requested location slot.  */
	  ix = *ix_p;
	  lto_streamer_cache_add_to_node_array (cache, ix, t);
	}

      /* Indicate that T was already in the cache.  */
      existed_p = true;
    }

  if (ix_p)
    *ix_p = ix;

  return existed_p;
}


/* Insert tree node T in CACHE.  If T already existed in the cache
   return true.  Otherwise, return false.

   If IX_P is non-null, update it with the index into the cache where
   T has been stored.  */

bool
lto_streamer_cache_insert (struct lto_streamer_cache_d *cache, tree t,
			   unsigned *ix_p)
{
  return lto_streamer_cache_insert_1 (cache, t, ix_p, true);
}


/* Insert tree node T in CACHE at slot IX.  If T already
   existed in the cache return true.  Otherwise, return false.  */

bool
lto_streamer_cache_insert_at (struct lto_streamer_cache_d *cache,
			      tree t, unsigned ix)
{
  return lto_streamer_cache_insert_1 (cache, t, &ix, false);
}


/* Appends tree node T to CACHE, even if T already existed in it.  */

void
lto_streamer_cache_append (struct lto_streamer_cache_d *cache, tree t)
{
  unsigned ix = VEC_length (tree, cache->nodes);
  lto_streamer_cache_insert_1 (cache, t, &ix, false);
}

/* Return true if tree node T exists in CACHE, otherwise false.  If IX_P is
   not NULL, write to *IX_P the index into the cache where T is stored
   ((unsigned)-1 if T is not found).  */

bool
lto_streamer_cache_lookup (struct lto_streamer_cache_d *cache, tree t,
			   unsigned *ix_p)
{
  void **slot;
  bool retval;
  unsigned ix;

  gcc_assert (t);

  slot = pointer_map_contains  (cache->node_map, t);
  if (slot == NULL)
    {
      retval = false;
      ix = -1;
    }
  else
    {
      retval = true;
      ix = (size_t) *slot - 1;
    }

  if (ix_p)
    *ix_p = ix;

  return retval;
}


/* Return the tree node at slot IX in CACHE.  */

tree
lto_streamer_cache_get (struct lto_streamer_cache_d *cache, unsigned ix)
{
  gcc_assert (cache);

  /* Make sure we're not requesting something we don't have.  */
  gcc_assert (ix < VEC_length (tree, cache->nodes));

  return VEC_index (tree, cache->nodes, ix);
}


/* Record NODE in COMMON_NODES if it is not NULL and is not already in
   SEEN_NODES.  */

static void
lto_record_common_node (tree *nodep, VEC(tree, heap) **common_nodes,
			struct pointer_set_t *seen_nodes)
{
  tree node = *nodep;

  if (node == NULL_TREE)
    return;

  if (TYPE_P (node))
    {
      /* Type merging will get confused by the canonical types as they
	 are set by the middle-end.  */
      if (in_lto_p)
	TYPE_CANONICAL (node) = NULL_TREE;
      node = gimple_register_type (node);
      TYPE_CANONICAL (node) = gimple_register_canonical_type (node);
      if (in_lto_p)
	TYPE_CANONICAL (*nodep) = TYPE_CANONICAL (node);
      *nodep = node;
    }

  /* Return if node is already seen.  */
  if (pointer_set_insert (seen_nodes, node))
    return;

  VEC_safe_push (tree, heap, *common_nodes, node);

  if (POINTER_TYPE_P (node)
      || TREE_CODE (node) == COMPLEX_TYPE
      || TREE_CODE (node) == ARRAY_TYPE)
    lto_record_common_node (&TREE_TYPE (node), common_nodes, seen_nodes);
}


/* Generate a vector of common nodes and make sure they are merged
   properly according to the gimple type table.  */

static VEC(tree,heap) *
lto_get_common_nodes (void)
{
  unsigned i;
  VEC(tree,heap) *common_nodes = NULL;
  struct pointer_set_t *seen_nodes;

  /* The MAIN_IDENTIFIER_NODE is normally set up by the front-end, but the
     LTO back-end must agree. Currently, the only languages that set this
     use the name "main".  */
  if (main_identifier_node)
    {
      const char *main_name = IDENTIFIER_POINTER (main_identifier_node);
      gcc_assert (strcmp (main_name, "main") == 0);
    }
  else
    main_identifier_node = get_identifier ("main");

  gcc_assert (ptrdiff_type_node == integer_type_node);

  /* FIXME lto.  In the C++ front-end, fileptr_type_node is defined as a
     variant copy of of ptr_type_node, rather than ptr_node itself.  The
     distinction should only be relevant to the front-end, so we always
     use the C definition here in lto1.

     These should be assured in pass_ipa_free_lang_data.  */
  gcc_assert (fileptr_type_node == ptr_type_node);
  gcc_assert (TYPE_MAIN_VARIANT (fileptr_type_node) == ptr_type_node);

  seen_nodes = pointer_set_create ();

  /* Skip itk_char.  char_type_node is shared with the appropriately
     signed variant.  */
  for (i = itk_signed_char; i < itk_none; i++)
    lto_record_common_node (&integer_types[i], &common_nodes, seen_nodes);

  for (i = 0; i < TYPE_KIND_LAST; i++)
    lto_record_common_node (&sizetype_tab[i], &common_nodes, seen_nodes);

  for (i = 0; i < TI_MAX; i++)
    lto_record_common_node (&global_trees[i], &common_nodes, seen_nodes);

  pointer_set_destroy (seen_nodes);

  return common_nodes;
}


/* Assign an index to tree node T and enter it in the streamer cache
   CACHE.  */

static void
preload_common_node (struct lto_streamer_cache_d *cache, tree t)
{
  gcc_assert (t);

  lto_streamer_cache_insert (cache, t, NULL);

 /* The FIELD_DECLs of structures should be shared, so that every
    COMPONENT_REF uses the same tree node when referencing a field.
    Pointer equality between FIELD_DECLs is used by the alias
    machinery to compute overlapping memory references (See
    nonoverlapping_component_refs_p).  */
 if (TREE_CODE (t) == RECORD_TYPE)
   {
     tree f;

     for (f = TYPE_FIELDS (t); f; f = TREE_CHAIN (f))
       preload_common_node (cache, f);
   }
}


/* Create a cache of pickled nodes.  */

struct lto_streamer_cache_d *
lto_streamer_cache_create (void)
{
  struct lto_streamer_cache_d *cache;
  VEC(tree, heap) *common_nodes;
  unsigned i;
  tree node;

  cache = XCNEW (struct lto_streamer_cache_d);

  cache->node_map = pointer_map_create ();

  /* Load all the well-known tree nodes that are always created by
     the compiler on startup.  This prevents writing them out
     unnecessarily.  */
  common_nodes = lto_get_common_nodes ();

  FOR_EACH_VEC_ELT (tree, common_nodes, i, node)
    preload_common_node (cache, node);

  VEC_free(tree, heap, common_nodes);

  return cache;
}


/* Delete the streamer cache C.  */

void
lto_streamer_cache_delete (struct lto_streamer_cache_d *c)
{
  if (c == NULL)
    return;

  pointer_map_destroy (c->node_map);
  VEC_free (tree, heap, c->nodes);
  free (c);
}


#ifdef LTO_STREAMER_DEBUG
static htab_t tree_htab;

struct tree_hash_entry
{
  tree key;
  intptr_t value;
};

static hashval_t
hash_tree (const void *p)
{
  const struct tree_hash_entry *e = (const struct tree_hash_entry *) p;
  return htab_hash_pointer (e->key);
}

static int
eq_tree (const void *p1, const void *p2)
{
  const struct tree_hash_entry *e1 = (const struct tree_hash_entry *) p1;
  const struct tree_hash_entry *e2 = (const struct tree_hash_entry *) p2;
  return (e1->key == e2->key);
}
#endif

/* Initialization common to the LTO reader and writer.  */

void
lto_streamer_init (void)
{
  /* Check that all the TS_* handled by the reader and writer routines
     match exactly the structures defined in treestruct.def.  When a
     new TS_* astructure is added, the streamer should be updated to
     handle it.  */
  check_handled_ts_structures ();

#ifdef LTO_STREAMER_DEBUG
  tree_htab = htab_create (31, hash_tree, eq_tree, NULL);
#endif
}


/* Gate function for all LTO streaming passes.  */

bool
gate_lto_out (void)
{
  return ((flag_generate_lto || in_lto_p)
	  /* Don't bother doing anything if the program has errors.  */
	  && !seen_error ());
}


#ifdef LTO_STREAMER_DEBUG
/* Add a mapping between T and ORIG_T, which is the numeric value of
   the original address of T as it was seen by the LTO writer.  This
   mapping is useful when debugging streaming problems.  A debugging
   session can be started on both reader and writer using ORIG_T
   as a breakpoint value in both sessions.

   Note that this mapping is transient and only valid while T is
   being reconstructed.  Once T is fully built, the mapping is
   removed.  */

void
lto_orig_address_map (tree t, intptr_t orig_t)
{
  struct tree_hash_entry ent;
  struct tree_hash_entry **slot;

  ent.key = t;
  ent.value = orig_t;
  slot
    = (struct tree_hash_entry **) htab_find_slot (tree_htab, &ent, INSERT);
  gcc_assert (!*slot);
  *slot = XNEW (struct tree_hash_entry);
  **slot = ent;
}


/* Get the original address of T as it was seen by the writer.  This
   is only valid while T is being reconstructed.  */

intptr_t
lto_orig_address_get (tree t)
{
  struct tree_hash_entry ent;
  struct tree_hash_entry **slot;

  ent.key = t;
  slot
    = (struct tree_hash_entry **) htab_find_slot (tree_htab, &ent, NO_INSERT);
  return (slot ? (*slot)->value : 0);
}


/* Clear the mapping of T to its original address.  */

void
lto_orig_address_remove (tree t)
{
  struct tree_hash_entry ent;
  struct tree_hash_entry **slot;

  ent.key = t;
  slot
    = (struct tree_hash_entry **) htab_find_slot (tree_htab, &ent, NO_INSERT);
  gcc_assert (slot);
  free (*slot);
  htab_clear_slot (tree_htab, (PTR *)slot);
}
#endif


/* Check that the version MAJOR.MINOR is the correct version number.  */

void
lto_check_version (int major, int minor)
{
  if (major != LTO_major_version || minor != LTO_minor_version)
    fatal_error ("bytecode stream generated with LTO version %d.%d instead "
	         "of the expected %d.%d",
		 major, minor,
		 LTO_major_version, LTO_minor_version);
}