gcc/vec.c

/* Vector API for GNU compiler.
   Copyright (C) 2004-2013 Free Software Foundation, Inc.
   Contributed by Nathan Sidwell <nathan@codesourcery.com>
   Re-implemented in C++ by Diego Novillo <dnovillo@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/>.  */

/* This file is compiled twice: once for the generator programs
   once for the compiler.  */
#ifdef GENERATOR_FILE
#include "bconfig.h"
#else
#include "config.h"
#endif

#include "system.h"
#include "coretypes.h"
#include "ggc.h"
#include "vec.h"
#include "diagnostic-core.h"
#include "hashtab.h"

/* vNULL is an empty type with a template cast operation that returns
   a zero-initialized vec<T, A, L> instance.  Use this when you want
   to assign nil values to new vec instances or pass a nil vector as
   a function call argument.

   We use this technique because vec<T, A, L> must be PODs (they are
   stored in unions and passed in vararg functions), this means that
   they cannot have ctors/dtors.  */
vnull vNULL;


/* Store information about each particular vector.  */
struct vec_descriptor
{
  const char *function;
  const char *file;
  int line;
  size_t allocated;
  size_t times;
  size_t peak;
};


/* Hashtable mapping vec addresses to descriptors.  */
static htab_t vec_desc_hash;

/* Hashtable helpers.  */
static hashval_t
hash_descriptor (const void *p)
{
  const struct vec_descriptor *const d =
    (const struct vec_descriptor *) p;
  return htab_hash_pointer (d->file) + d->line;
}
static int
eq_descriptor (const void *p1, const void *p2)
{
  const struct vec_descriptor *const d = (const struct vec_descriptor *) p1;
  const struct vec_descriptor *const l = (const struct vec_descriptor *) p2;
  return d->file == l->file && d->function == l->function && d->line == l->line;
}

/* Hashtable converting address of allocated field to loc descriptor.  */
static htab_t ptr_hash;
struct ptr_hash_entry
{
  void *ptr;
  struct vec_descriptor *loc;
  size_t allocated;
};

/* Hash table helpers functions.  */
static hashval_t
hash_ptr (const void *p)
{
  const struct ptr_hash_entry *const d = (const struct ptr_hash_entry *) p;

  return htab_hash_pointer (d->ptr);
}

static int
eq_ptr (const void *p1, const void *p2)
{
  const struct ptr_hash_entry *const p = (const struct ptr_hash_entry *) p1;

  return (p->ptr == p2);
}

/* Return descriptor for given call site, create new one if needed.  */
static struct vec_descriptor *
vec_descriptor (const char *name, int line, const char *function)
{
  struct vec_descriptor loc;
  struct vec_descriptor **slot;

  loc.file = name;
  loc.line = line;
  loc.function = function;
  if (!vec_desc_hash)
    vec_desc_hash = htab_create (10, hash_descriptor, eq_descriptor, NULL);

  slot = (struct vec_descriptor **) htab_find_slot (vec_desc_hash, &loc,
						    INSERT);
  if (*slot)
    return *slot;
  *slot = XCNEW (struct vec_descriptor);
  (*slot)->file = name;
  (*slot)->line = line;
  (*slot)->function = function;
  (*slot)->allocated = 0;
  (*slot)->peak = 0;
  return *slot;
}

/* Account the overhead.  */

void
vec_prefix::register_overhead (size_t size, const char *name, int line,
			       const char *function)
{
  struct vec_descriptor *loc = vec_descriptor (name, line, function);
  struct ptr_hash_entry *p = XNEW (struct ptr_hash_entry);
  PTR *slot;

  p->ptr = this;
  p->loc = loc;
  p->allocated = size;
  if (!ptr_hash)
    ptr_hash = htab_create (10, hash_ptr, eq_ptr, NULL);
  slot = htab_find_slot_with_hash (ptr_hash, this, htab_hash_pointer (this),
				   INSERT);
  gcc_assert (!*slot);
  *slot = p;

  loc->allocated += size;
  if (loc->peak < loc->allocated)
    loc->peak += loc->allocated;
  loc->times++;
}


/* Notice that the memory allocated for the vector has been freed.  */

void
vec_prefix::release_overhead (void)
{
  PTR *slot = htab_find_slot_with_hash (ptr_hash, this,
					htab_hash_pointer (this),
					NO_INSERT);
  struct ptr_hash_entry *p = (struct ptr_hash_entry *) *slot;
  p->loc->allocated -= p->allocated;
  htab_clear_slot (ptr_hash, slot);
  ::free (p);
}


/* Calculate the number of slots to reserve a vector, making sure that
   RESERVE slots are free.  If EXACT grow exactly, otherwise grow
   exponentially.  PFX is the control data for the vector.  */

unsigned
vec_prefix::calculate_allocation (vec_prefix *pfx, unsigned reserve,
				  bool exact)
{
  unsigned alloc = 0;
  unsigned num = 0;

  if (pfx)
    {
      alloc = pfx->alloc_;
      num = pfx->num_;
    }
  else if (!reserve)
    /* If there's no vector, and we've not requested anything, then we
       will create a NULL vector.  */
    return 0;

  /* We must have run out of room.  */
  gcc_assert (alloc - num < reserve);

  if (exact)
    /* Exact size.  */
    alloc = num + reserve;
  else
    {
      /* Exponential growth. */
      if (!alloc)
	alloc = 4;
      else if (alloc < 16)
	/* Double when small.  */
	alloc = alloc * 2;
      else
	/* Grow slower when large.  */
	alloc = (alloc * 3 / 2);

      /* If this is still too small, set it to the right size. */
      if (alloc < num + reserve)
	alloc = num + reserve;
    }
  return alloc;
}


/* Stack vectors are a little different.  VEC_alloc turns into a call
   to vec<T, A>::stack_reserve and passes in space allocated via a
   call to alloca.  We record that pointer so that we know that we
   shouldn't free it.  If the vector is resized, we resize it on the
   heap.  We record the pointers in a vector and search it in LIFO
   order--i.e., we look for the newest stack vectors first.  We don't
   expect too many stack vectors at any one level, and searching from
   the end should normally be efficient even if they are used in a
   recursive function.  */

static vec<void *> stack_vecs;

/* Add a stack vector to STACK_VECS.  */

void
register_stack_vec (void *vec)
{
  stack_vecs.safe_push (vec);
}


/* If VEC is registered in STACK_VECS, return its index.
   Otherwise, return -1.  */

int
stack_vec_register_index (void *vec)
{
  for (unsigned ix = stack_vecs.length (); ix > 0; --ix)
    if (stack_vecs[ix - 1] == vec)
      return static_cast<int> (ix - 1);
  return -1;
}


/* Remove vector at slot IX from the list of registered stack vectors.  */

void
unregister_stack_vec (unsigned ix)
{
  stack_vecs.unordered_remove (ix);
}


/* Helper for qsort; sort descriptors by amount of memory consumed.  */

static int
cmp_statistic (const void *loc1, const void *loc2)
{
  const struct vec_descriptor *const l1 =
    *(const struct vec_descriptor *const *) loc1;
  const struct vec_descriptor *const l2 =
    *(const struct vec_descriptor *const *) loc2;
  long diff;
  diff = l1->allocated - l2->allocated;
  if (!diff)
    diff = l1->peak - l2->peak;
  if (!diff)
    diff = l1->times - l2->times;
  return diff > 0 ? 1 : diff < 0 ? -1 : 0;
}


/* Collect array of the descriptors from hashtable.  */

static struct vec_descriptor **loc_array;
static int
add_statistics (void **slot, void *b)
{
  int *n = (int *)b;
  loc_array[*n] = (struct vec_descriptor *) *slot;
  (*n)++;
  return 1;
}

/* Dump per-site memory statistics.  */

void
dump_vec_loc_statistics (void)
{
  int nentries = 0;
  char s[4096];
  size_t allocated = 0;
  size_t times = 0;
  int i;

  if (! GATHER_STATISTICS)
    return;

  loc_array = XCNEWVEC (struct vec_descriptor *, vec_desc_hash->n_elements);
  fprintf (stderr, "Heap vectors:\n");
  fprintf (stderr, "\n%-48s %10s       %10s       %10s\n",
	   "source location", "Leak", "Peak", "Times");
  fprintf (stderr, "-------------------------------------------------------\n");
  htab_traverse (vec_desc_hash, add_statistics, &nentries);
  qsort (loc_array, nentries, sizeof (*loc_array), cmp_statistic);
  for (i = 0; i < nentries; i++)
    {
      struct vec_descriptor *d = loc_array[i];
      allocated += d->allocated;
      times += d->times;
    }
  for (i = 0; i < nentries; i++)
    {
      struct vec_descriptor *d = loc_array[i];
      const char *s1 = d->file;
      const char *s2;
      while ((s2 = strstr (s1, "gcc/")))
	s1 = s2 + 4;
      sprintf (s, "%s:%i (%s)", s1, d->line, d->function);
      s[48] = 0;
      fprintf (stderr, "%-48s %10li:%4.1f%% %10li      %10li:%4.1f%% \n", s,
	       (long)d->allocated,
	       (d->allocated) * 100.0 / allocated,
	       (long)d->peak,
	       (long)d->times,
	       (d->times) * 100.0 / times);
    }
  fprintf (stderr, "%-48s %10ld                        %10ld\n",
	   "Total", (long)allocated, (long)times);
  fprintf (stderr, "\n%-48s %10s       %10s       %10s\n",
	   "source location", "Leak", "Peak", "Times");
  fprintf (stderr, "-------------------------------------------------------\n");
}