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/* Simple garbage collection for the GNU compiler.

   Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,

   2009, 2010 Free Software Foundation, Inc.

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/>.  */

/* Generic garbage collection (GC) functions and data, not specific to

   any particular GC implementation.  */

#include "config.h"

#include "system.h"

#include "coretypes.h"

#include "hashtab.h"

#include "ggc.h"

#include "ggc-internal.h"

#include "diagnostic-core.h"

#include "params.h"

#include "hosthooks.h"

#include "hosthooks-def.h"

#include "plugin.h"

#include "vec.h"

#include "timevar.h"

/* When set, ggc_collect will do collection.  */

bool ggc_force_collect;

/* When true, protect the contents of the identifier hash table.  */

bool ggc_protect_identifiers = true;

/* Statistics about the allocation.  */

static ggc_statistics *ggc_stats;

struct traversal_state;

static int ggc_htab_delete (void **, void *);

static hashval_t saving_htab_hash (const void *);

static int saving_htab_eq (const void *, const void *);

static int call_count (void **, void *);

static int call_alloc (void **, void *);

static int compare_ptr_data (const void *, const void *);

static void relocate_ptrs (void *, void *);

static void write_pch_globals (const struct ggc_root_tab * const *tab,

                               struct traversal_state *state);

/* Maintain global roots that are preserved during GC.  */

/* Process a slot of an htab by deleting it if it has not been marked.  */

static int

ggc_htab_delete (void **slot, void *info)

{

  const struct ggc_cache_tab *r = (const struct ggc_cache_tab *) info;

  if (! (*r->marked_p) (*slot))

    htab_clear_slot (*r->base, slot);

  else

    (*r->cb) (*slot);

  return 1;

}

/* This extra vector of dynamically registered root_tab-s is used by

   ggc_mark_roots and gives the ability to dynamically add new GGC root

   tables, for instance from some plugins; this vector is on the heap

   since it is used by GGC internally.  */

typedef const struct ggc_root_tab *const_ggc_root_tab_t;

DEF_VEC_P(const_ggc_root_tab_t);

DEF_VEC_ALLOC_P(const_ggc_root_tab_t, heap);

static VEC(const_ggc_root_tab_t, heap) *extra_root_vec;

/* Dynamically register a new GGC root table RT. This is useful for

   plugins. */

void

ggc_register_root_tab (const struct ggc_root_tab* rt)

{

  if (rt)

    VEC_safe_push (const_ggc_root_tab_t, heap, extra_root_vec, rt);

}

/* This extra vector of dynamically registered cache_tab-s is used by

   ggc_mark_roots and gives the ability to dynamically add new GGC cache

   tables, for instance from some plugins; this vector is on the heap

   since it is used by GGC internally.  */

typedef const struct ggc_cache_tab *const_ggc_cache_tab_t;

DEF_VEC_P(const_ggc_cache_tab_t);

DEF_VEC_ALLOC_P(const_ggc_cache_tab_t, heap);

static VEC(const_ggc_cache_tab_t, heap) *extra_cache_vec;

/* Dynamically register a new GGC cache table CT. This is useful for

   plugins. */

void

ggc_register_cache_tab (const struct ggc_cache_tab* ct)

{

  if (ct)

    VEC_safe_push (const_ggc_cache_tab_t, heap, extra_cache_vec, ct);

}

/* Scan a hash table that has objects which are to be deleted if they are not

   already marked.  */

static void

ggc_scan_cache_tab (const_ggc_cache_tab_t ctp)

{

  const struct ggc_cache_tab *cti;

  for (cti = ctp; cti->base != NULL; cti++)

    if (*cti->base)

      {

        ggc_set_mark (*cti->base);

        htab_traverse_noresize (*cti->base, ggc_htab_delete,

                                CONST_CAST (void *, (const void *)cti));

        ggc_set_mark ((*cti->base)->entries);

      }

}

/* Mark all the roots in the table RT.  */

static void

ggc_mark_root_tab (const_ggc_root_tab_t rt)

{

  size_t i;

  for ( ; rt->base != NULL; rt++)

    for (i = 0; i < rt->nelt; i++)

      (*rt->cb) (*(void **) ((char *)rt->base + rt->stride * i));

}

/* Iterate through all registered roots and mark each element.  */

void

ggc_mark_roots (void)

{

  const struct ggc_root_tab *const *rt;

  const_ggc_root_tab_t rtp, rti;

  const struct ggc_cache_tab *const *ct;

  const_ggc_cache_tab_t ctp;

  size_t i;

  for (rt = gt_ggc_deletable_rtab; *rt; rt++)

    for (rti = *rt; rti->base != NULL; rti++)

      memset (rti->base, 0, rti->stride);

  for (rt = gt_ggc_rtab; *rt; rt++)

    ggc_mark_root_tab (*rt);

  FOR_EACH_VEC_ELT (const_ggc_root_tab_t, extra_root_vec, i, rtp)

    ggc_mark_root_tab (rtp);

  if (ggc_protect_identifiers)

    ggc_mark_stringpool ();

  /* Now scan all hash tables that have objects which are to be deleted if

     they are not already marked.  */

  for (ct = gt_ggc_cache_rtab; *ct; ct++)

    ggc_scan_cache_tab (*ct);

  FOR_EACH_VEC_ELT (const_ggc_cache_tab_t, extra_cache_vec, i, ctp)

    ggc_scan_cache_tab (ctp);

  if (! ggc_protect_identifiers)

    ggc_purge_stringpool ();

  /* Some plugins may call ggc_set_mark from here.  */

  invoke_plugin_callbacks (PLUGIN_GGC_MARKING, NULL);

}

/* Allocate a block of memory, then clear it.  */

void *

ggc_internal_cleared_alloc_stat (size_t size MEM_STAT_DECL)

{

  void *buf = ggc_internal_alloc_stat (size PASS_MEM_STAT);

  memset (buf, 0, size);

  return buf;

}

/* Resize a block of memory, possibly re-allocating it.  */

void *

ggc_realloc_stat (void *x, size_t size MEM_STAT_DECL)

{

  void *r;

  size_t old_size;

  if (x == NULL)

    return ggc_internal_alloc_stat (size PASS_MEM_STAT);

  old_size = ggc_get_size (x);

  if (size <= old_size)

    {

      /* Mark the unwanted memory as unaccessible.  We also need to make

         the "new" size accessible, since ggc_get_size returns the size of

         the pool, not the size of the individually allocated object, the

         size which was previously made accessible.  Unfortunately, we

         don't know that previously allocated size.  Without that

         knowledge we have to lose some initialization-tracking for the

         old parts of the object.  An alternative is to mark the whole

         old_size as reachable, but that would lose tracking of writes

         after the end of the object (by small offsets).  Discard the

         handle to avoid handle leak.  */

      VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS ((char *) x + size,

                                                    old_size - size));

      VALGRIND_DISCARD (VALGRIND_MAKE_MEM_DEFINED (x, size));

      return x;

    }

  r = ggc_internal_alloc_stat (size PASS_MEM_STAT);

  /* Since ggc_get_size returns the size of the pool, not the size of the

     individually allocated object, we'd access parts of the old object

     that were marked invalid with the memcpy below.  We lose a bit of the

     initialization-tracking since some of it may be uninitialized.  */

  VALGRIND_DISCARD (VALGRIND_MAKE_MEM_DEFINED (x, old_size));

  memcpy (r, x, old_size);

  /* The old object is not supposed to be used anymore.  */

  ggc_free (x);

  return r;

}

void *

ggc_cleared_alloc_htab_ignore_args (size_t c ATTRIBUTE_UNUSED,

                                    size_t n ATTRIBUTE_UNUSED)

{

  gcc_assert (c * n == sizeof (struct htab));

  return ggc_alloc_cleared_htab ();

}

/* TODO: once we actually use type information in GGC, create a new tag

   gt_gcc_ptr_array and use it for pointer arrays.  */

void *

ggc_cleared_alloc_ptr_array_two_args (size_t c, size_t n)

{

  gcc_assert (sizeof (PTR *) == n);

  return ggc_internal_cleared_vec_alloc (sizeof (PTR *), c);

}

/* These are for splay_tree_new_ggc.  */

void *

ggc_splay_alloc (enum gt_types_enum obj_type ATTRIBUTE_UNUSED, int sz,

                 void *nl)

{

  gcc_assert (!nl);

  return ggc_internal_alloc (sz);

}

void

ggc_splay_dont_free (void * x ATTRIBUTE_UNUSED, void *nl)

{

  gcc_assert (!nl);

}

/* Print statistics that are independent of the collector in use.  */

#define SCALE(x) ((unsigned long) ((x) < 1024*10 \

                  ? (x) \

                  : ((x) < 1024*1024*10 \

                     ? (x) / 1024 \

                     : (x) / (1024*1024))))

#define LABEL(x) ((x) < 1024*10 ? ' ' : ((x) < 1024*1024*10 ? 'k' : 'M'))

void

ggc_print_common_statistics (FILE *stream ATTRIBUTE_UNUSED,

                             ggc_statistics *stats)

{

  /* Set the pointer so that during collection we will actually gather

     the statistics.  */

  ggc_stats = stats;

  /* Then do one collection to fill in the statistics.  */

  ggc_collect ();

  /* At present, we don't really gather any interesting statistics.  */

  /* Don't gather statistics any more.  */

  ggc_stats = NULL;

}

/* Functions for saving and restoring GCable memory to disk.  */

static htab_t saving_htab;

struct ptr_data

{

  void *obj;

  void *note_ptr_cookie;

  gt_note_pointers note_ptr_fn;

  gt_handle_reorder reorder_fn;

  size_t size;

  void *new_addr;

  enum gt_types_enum type;

};

#define POINTER_HASH(x) (hashval_t)((long)x >> 3)

/* Register an object in the hash table.  */

int

gt_pch_note_object (void *obj, void *note_ptr_cookie,

                    gt_note_pointers note_ptr_fn,

                    enum gt_types_enum type)

{

  struct ptr_data **slot;

  if (obj == NULL || obj == (void *) 1)

    return 0;

  slot = (struct ptr_data **)

    htab_find_slot_with_hash (saving_htab, obj, POINTER_HASH (obj),

                              INSERT);

  if (*slot != NULL)

    {

      gcc_assert ((*slot)->note_ptr_fn == note_ptr_fn

                  && (*slot)->note_ptr_cookie == note_ptr_cookie);

      return 0;

    }

  *slot = XCNEW (struct ptr_data);

  (*slot)->obj = obj;

  (*slot)->note_ptr_fn = note_ptr_fn;

  (*slot)->note_ptr_cookie = note_ptr_cookie;

  if (note_ptr_fn == gt_pch_p_S)

    (*slot)->size = strlen ((const char *)obj) + 1;

  else

    (*slot)->size = ggc_get_size (obj);

  (*slot)->type = type;

  return 1;

}

/* Register an object in the hash table.  */

void

gt_pch_note_reorder (void *obj, void *note_ptr_cookie,

                     gt_handle_reorder reorder_fn)

{

  struct ptr_data *data;

  if (obj == NULL || obj == (void *) 1)

    return;

  data = (struct ptr_data *)

    htab_find_with_hash (saving_htab, obj, POINTER_HASH (obj));

  gcc_assert (data && data->note_ptr_cookie == note_ptr_cookie);

  data->reorder_fn = reorder_fn;

}

/* Hash and equality functions for saving_htab, callbacks for htab_create.  */

static hashval_t

saving_htab_hash (const void *p)

{

  return POINTER_HASH (((const struct ptr_data *)p)->obj);

}

static int

saving_htab_eq (const void *p1, const void *p2)

{

  return ((const struct ptr_data *)p1)->obj == p2;

}

/* Handy state for the traversal functions.  */

struct traversal_state

{

  FILE *f;

  struct ggc_pch_data *d;

  size_t count;

  struct ptr_data **ptrs;

  size_t ptrs_i;

};

/* Callbacks for htab_traverse.  */

static int

call_count (void **slot, void *state_p)

{

  struct ptr_data *d = (struct ptr_data *)*slot;

  struct traversal_state *state = (struct traversal_state *)state_p;

  ggc_pch_count_object (state->d, d->obj, d->size,

                        d->note_ptr_fn == gt_pch_p_S,

                        d->type);

  state->count++;

  return 1;

}

static int

call_alloc (void **slot, void *state_p)

{

  struct ptr_data *d = (struct ptr_data *)*slot;

  struct traversal_state *state = (struct traversal_state *)state_p;

  d->new_addr = ggc_pch_alloc_object (state->d, d->obj, d->size,

                                      d->note_ptr_fn == gt_pch_p_S,

                                      d->type);

  state->ptrs[state->ptrs_i++] = d;

  return 1;

}

/* Callback for qsort.  */

static int

compare_ptr_data (const void *p1_p, const void *p2_p)

{

  const struct ptr_data *const p1 = *(const struct ptr_data *const *)p1_p;

  const struct ptr_data *const p2 = *(const struct ptr_data *const *)p2_p;

  return (((size_t)p1->new_addr > (size_t)p2->new_addr)

          - ((size_t)p1->new_addr < (size_t)p2->new_addr));

}

/* Callbacks for note_ptr_fn.  */

static void

relocate_ptrs (void *ptr_p, void *state_p)

{

  void **ptr = (void **)ptr_p;

  struct traversal_state *state ATTRIBUTE_UNUSED

    = (struct traversal_state *)state_p;

  struct ptr_data *result;

  if (*ptr == NULL || *ptr == (void *)1)

    return;

  result = (struct ptr_data *)

    htab_find_with_hash (saving_htab, *ptr, POINTER_HASH (*ptr));

  gcc_assert (result);

  *ptr = result->new_addr;

}

/* Write out, after relocation, the pointers in TAB.  */

static void

write_pch_globals (const struct ggc_root_tab * const *tab,

                   struct traversal_state *state)

{

  const struct ggc_root_tab *const *rt;

  const struct ggc_root_tab *rti;

  size_t i;

  for (rt = tab; *rt; rt++)

    for (rti = *rt; rti->base != NULL; rti++)

      for (i = 0; i < rti->nelt; i++)

        {

          void *ptr = *(void **)((char *)rti->base + rti->stride * i);

          struct ptr_data *new_ptr;

          if (ptr == NULL || ptr == (void *)1)

            {

              if (fwrite (&ptr, sizeof (void *), 1, state->f)

                  != 1)

                fatal_error ("can%'t write PCH file: %m");

            }

          else

            {

              new_ptr = (struct ptr_data *)

                htab_find_with_hash (saving_htab, ptr, POINTER_HASH (ptr));

              if (fwrite (&new_ptr->new_addr, sizeof (void *), 1, state->f)

                  != 1)

                fatal_error ("can%'t write PCH file: %m");

            }

        }

}

/* Hold the information we need to mmap the file back in.  */

struct mmap_info

{

  size_t offset;

  size_t size;

  void *preferred_base;

};

/* Write out the state of the compiler to F.  */

void

gt_pch_save (FILE *f)

{

  const struct ggc_root_tab *const *rt;

  const struct ggc_root_tab *rti;

  size_t i;

  struct traversal_state state;

  char *this_object = NULL;

  size_t this_object_size = 0;

  struct mmap_info mmi;

  const size_t mmap_offset_alignment = host_hooks.gt_pch_alloc_granularity();

  gt_pch_save_stringpool ();

  timevar_push (TV_PCH_PTR_REALLOC);

  saving_htab = htab_create (50000, saving_htab_hash, saving_htab_eq, free);

  for (rt = gt_ggc_rtab; *rt; rt++)

    for (rti = *rt; rti->base != NULL; rti++)

      for (i = 0; i < rti->nelt; i++)

        (*rti->pchw)(*(void **)((char *)rti->base + rti->stride * i));

  for (rt = gt_pch_cache_rtab; *rt; rt++)

    for (rti = *rt; rti->base != NULL; rti++)

      for (i = 0; i < rti->nelt; i++)

        (*rti->pchw)(*(void **)((char *)rti->base + rti->stride * i));

  /* Prepare the objects for writing, determine addresses and such.  */

  state.f = f;

  state.d = init_ggc_pch ();

  state.count = 0;

  htab_traverse (saving_htab, call_count, &state);

  mmi.size = ggc_pch_total_size (state.d);

  /* Try to arrange things so that no relocation is necessary, but

     don't try very hard.  On most platforms, this will always work,

     and on the rest it's a lot of work to do better.

     (The extra work goes in HOST_HOOKS_GT_PCH_GET_ADDRESS and

     HOST_HOOKS_GT_PCH_USE_ADDRESS.)  */

  mmi.preferred_base = host_hooks.gt_pch_get_address (mmi.size, fileno (f));

  ggc_pch_this_base (state.d, mmi.preferred_base);

  state.ptrs = XNEWVEC (struct ptr_data *, state.count);

  state.ptrs_i = 0;

  htab_traverse (saving_htab, call_alloc, &state);

  timevar_pop (TV_PCH_PTR_REALLOC);

  timevar_push (TV_PCH_PTR_SORT);

  qsort (state.ptrs, state.count, sizeof (*state.ptrs), compare_ptr_data);

  timevar_pop (TV_PCH_PTR_SORT);

  /* Write out all the scalar variables.  */

  for (rt = gt_pch_scalar_rtab; *rt; rt++)

    for (rti = *rt; rti->base != NULL; rti++)

      if (fwrite (rti->base, rti->stride, 1, f) != 1)

        fatal_error ("can%'t write PCH file: %m");

  /* Write out all the global pointers, after translation.  */

  write_pch_globals (gt_ggc_rtab, &state);

  write_pch_globals (gt_pch_cache_rtab, &state);

  /* Pad the PCH file so that the mmapped area starts on an allocation

     granularity (usually page) boundary.  */

  {

    long o;

    o = ftell (state.f) + sizeof (mmi);

    if (o == -1)

      fatal_error ("can%'t get position in PCH file: %m");

    mmi.offset = mmap_offset_alignment - o % mmap_offset_alignment;

    if (mmi.offset == mmap_offset_alignment)

      mmi.offset = 0;

    mmi.offset += o;

  }

  if (fwrite (&mmi, sizeof (mmi), 1, state.f) != 1)

    fatal_error ("can%'t write PCH file: %m");

  if (mmi.offset != 0

      && fseek (state.f, mmi.offset, SEEK_SET) != 0)

    fatal_error ("can%'t write padding to PCH file: %m");

  ggc_pch_prepare_write (state.d, state.f);

  /* Actually write out the objects.  */

  for (i = 0; i < state.count; i++)

    {

      if (this_object_size < state.ptrs[i]->size)

        {

          this_object_size = state.ptrs[i]->size;

          this_object = XRESIZEVAR (char, this_object, this_object_size);

        }

      memcpy (this_object, state.ptrs[i]->obj, state.ptrs[i]->size);

      if (state.ptrs[i]->reorder_fn != NULL)

        state.ptrs[i]->reorder_fn (state.ptrs[i]->obj,

                                   state.ptrs[i]->note_ptr_cookie,

                                   relocate_ptrs, &state);

      state.ptrs[i]->note_ptr_fn (state.ptrs[i]->obj,

                                  state.ptrs[i]->note_ptr_cookie,

                                  relocate_ptrs, &state);

      ggc_pch_write_object (state.d, state.f, state.ptrs[i]->obj,

                            state.ptrs[i]->new_addr, state.ptrs[i]->size,

                            state.ptrs[i]->note_ptr_fn == gt_pch_p_S);

      if (state.ptrs[i]->note_ptr_fn != gt_pch_p_S)

        memcpy (state.ptrs[i]->obj, this_object, state.ptrs[i]->size);

    }

  ggc_pch_finish (state.d, state.f);

  gt_pch_fixup_stringpool ();

  free (state.ptrs);

  htab_delete (saving_htab);

}

/* Read the state of the compiler back in from F.  */

void

gt_pch_restore (FILE *f)

{

  const struct ggc_root_tab *const *rt;

  const struct ggc_root_tab *rti;

  size_t i;

  struct mmap_info mmi;

  int result;

  /* Delete any deletable objects.  This makes ggc_pch_read much

     faster, as it can be sure that no GCable objects remain other

     than the ones just read in.  */

  for (rt = gt_ggc_deletable_rtab; *rt; rt++)

    for (rti = *rt; rti->base != NULL; rti++)

      memset (rti->base, 0, rti->stride);

  /* Read in all the scalar variables.  */

  for (rt = gt_pch_scalar_rtab; *rt; rt++)

    for (rti = *rt; rti->base != NULL; rti++)

      if (fread (rti->base, rti->stride, 1, f) != 1)

        fatal_error ("can%'t read PCH file: %m");

  /* Read in all the global pointers, in 6 easy loops.  */

  for (rt = gt_ggc_rtab; *rt; rt++)

    for (rti = *rt; rti->base != NULL; rti++)

      for (i = 0; i < rti->nelt; i++)

        if (fread ((char *)rti->base + rti->stride * i,

                   sizeof (void *), 1, f) != 1)

          fatal_error ("can%'t read PCH file: %m");

  for (rt = gt_pch_cache_rtab; *rt; rt++)

    for (rti = *rt; rti->base != NULL; rti++)

      for (i = 0; i < rti->nelt; i++)

        if (fread ((char *)rti->base + rti->stride * i,

                   sizeof (void *), 1, f) != 1)

          fatal_error ("can%'t read PCH file: %m");