365 lines
9.9 KiB
C
365 lines
9.9 KiB
C
/* Simple garbage collection for the GNU compiler.
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Copyright (C) 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 2, or (at your option) any later
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING. If not, write to the Free
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Software Foundation, 59 Temple Place - Suite 330, Boston, MA
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02111-1307, USA. */
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/* Generic garbage collection (GC) functions and data, not specific to
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any particular GC implementation. */
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#include "config.h"
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#include "system.h"
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#include "rtl.h"
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#include "tree.h"
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#include "tm_p.h"
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#include "hashtab.h"
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#include "varray.h"
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#include "ggc.h"
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#include "langhooks.h"
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#include "params.h"
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#ifdef HAVE_SYS_RESOURCE_H
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# include <sys/resource.h>
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#endif
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#ifdef ENABLE_VALGRIND_CHECKING
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#include <valgrind.h>
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#else
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/* Avoid #ifdef:s when we can help it. */
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#define VALGRIND_DISCARD(x)
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#endif
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/* Statistics about the allocation. */
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static ggc_statistics *ggc_stats;
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static int ggc_htab_delete PARAMS ((void **, void *));
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static double ggc_rlimit_bound PARAMS ((double));
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/* Maintain global roots that are preserved during GC. */
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/* Global roots that are preserved during calls to gc. */
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struct ggc_root
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{
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struct ggc_root *next;
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void *base;
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int nelt;
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int size;
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void (*cb) PARAMS ((void *));
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};
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static struct ggc_root *roots;
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/* Add BASE as a new garbage collection root. It is an array of
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length NELT with each element SIZE bytes long. CB is a
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function that will be called with a pointer to each element
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of the array; it is the intention that CB call the appropriate
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routine to mark gc-able memory for that element. */
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void
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ggc_add_root (base, nelt, size, cb)
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void *base;
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int nelt, size;
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void (*cb) PARAMS ((void *));
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{
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struct ggc_root *x = (struct ggc_root *) xmalloc (sizeof (*x));
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x->next = roots;
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x->base = base;
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x->nelt = nelt;
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x->size = size;
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x->cb = cb;
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roots = x;
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}
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/* Process a slot of an htab by deleting it if it has not been marked. */
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static int
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ggc_htab_delete (slot, info)
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void **slot;
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void *info;
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{
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const struct ggc_cache_tab *r = (const struct ggc_cache_tab *) info;
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if (! (*r->marked_p) (*slot))
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htab_clear_slot (*r->base, slot);
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else
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(*r->cb) (*slot);
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return 1;
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}
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/* Iterate through all registered roots and mark each element. */
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void
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ggc_mark_roots ()
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{
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struct ggc_root *x;
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const struct ggc_root_tab *const *rt;
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const struct ggc_root_tab *rti;
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const struct ggc_cache_tab *const *ct;
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const struct ggc_cache_tab *cti;
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size_t i;
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for (rt = gt_ggc_deletable_rtab; *rt; rt++)
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for (rti = *rt; rti->base != NULL; rti++)
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memset (rti->base, 0, rti->stride);
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for (rt = gt_ggc_rtab; *rt; rt++)
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for (rti = *rt; rti->base != NULL; rti++)
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for (i = 0; i < rti->nelt; i++)
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(*rti->cb)(*(void **)((char *)rti->base + rti->stride * i));
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for (x = roots; x != NULL; x = x->next)
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{
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char *elt = x->base;
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int s = x->size, n = x->nelt;
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void (*cb) PARAMS ((void *)) = x->cb;
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int i;
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for (i = 0; i < n; ++i, elt += s)
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(*cb)(elt);
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}
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/* Now scan all hash tables that have objects which are to be deleted if
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they are not already marked. */
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for (ct = gt_ggc_cache_rtab; *ct; ct++)
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for (cti = *ct; cti->base != NULL; cti++)
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if (*cti->base)
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htab_traverse (*cti->base, ggc_htab_delete, (PTR) cti);
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}
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/* Allocate a block of memory, then clear it. */
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void *
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ggc_alloc_cleared (size)
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size_t size;
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{
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void *buf = ggc_alloc (size);
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memset (buf, 0, size);
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return buf;
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}
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/* Resize a block of memory, possibly re-allocating it. */
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void *
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ggc_realloc (x, size)
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void *x;
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size_t size;
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{
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void *r;
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size_t old_size;
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if (x == NULL)
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return ggc_alloc (size);
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old_size = ggc_get_size (x);
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if (size <= old_size)
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{
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/* Mark the unwanted memory as unaccessible. We also need to make
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the "new" size accessible, since ggc_get_size returns the size of
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the pool, not the size of the individually allocated object, the
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size which was previously made accessible. Unfortunately, we
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don't know that previously allocated size. Without that
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knowledge we have to lose some initialization-tracking for the
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old parts of the object. An alternative is to mark the whole
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old_size as reachable, but that would lose tracking of writes
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after the end of the object (by small offsets). Discard the
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handle to avoid handle leak. */
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VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS ((char *) x + size,
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old_size - size));
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VALGRIND_DISCARD (VALGRIND_MAKE_READABLE (x, size));
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return x;
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}
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r = ggc_alloc (size);
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/* Since ggc_get_size returns the size of the pool, not the size of the
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individually allocated object, we'd access parts of the old object
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that were marked invalid with the memcpy below. We lose a bit of the
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initialization-tracking since some of it may be uninitialized. */
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VALGRIND_DISCARD (VALGRIND_MAKE_READABLE (x, old_size));
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memcpy (r, x, old_size);
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/* The old object is not supposed to be used anymore. */
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VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS (x, old_size));
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return r;
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}
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/* Like ggc_alloc_cleared, but performs a multiplication. */
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void *
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ggc_calloc (s1, s2)
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size_t s1, s2;
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{
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return ggc_alloc_cleared (s1 * s2);
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}
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/* Print statistics that are independent of the collector in use. */
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#define SCALE(x) ((unsigned long) ((x) < 1024*10 \
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? (x) \
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: ((x) < 1024*1024*10 \
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? (x) / 1024 \
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: (x) / (1024*1024))))
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#define LABEL(x) ((x) < 1024*10 ? ' ' : ((x) < 1024*1024*10 ? 'k' : 'M'))
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void
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ggc_print_common_statistics (stream, stats)
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FILE *stream;
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ggc_statistics *stats;
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{
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int code;
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/* Set the pointer so that during collection we will actually gather
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the statistics. */
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ggc_stats = stats;
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/* Then do one collection to fill in the statistics. */
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ggc_collect ();
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/* Total the statistics. */
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for (code = 0; code < MAX_TREE_CODES; ++code)
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{
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stats->total_num_trees += stats->num_trees[code];
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stats->total_size_trees += stats->size_trees[code];
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}
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for (code = 0; code < NUM_RTX_CODE; ++code)
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{
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stats->total_num_rtxs += stats->num_rtxs[code];
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stats->total_size_rtxs += stats->size_rtxs[code];
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}
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/* Print the statistics for trees. */
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fprintf (stream, "\n%-17s%10s %16s %10s\n", "Tree",
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"Number", "Bytes", "% Total");
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for (code = 0; code < MAX_TREE_CODES; ++code)
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if (ggc_stats->num_trees[code])
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{
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fprintf (stream, "%-17s%10u%16ld%c %10.3f\n",
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tree_code_name[code],
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ggc_stats->num_trees[code],
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SCALE (ggc_stats->size_trees[code]),
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LABEL (ggc_stats->size_trees[code]),
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(100 * ((double) ggc_stats->size_trees[code])
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/ ggc_stats->total_size_trees));
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}
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fprintf (stream,
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"%-17s%10u%16ld%c\n", "Total",
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ggc_stats->total_num_trees,
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SCALE (ggc_stats->total_size_trees),
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LABEL (ggc_stats->total_size_trees));
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/* Print the statistics for RTL. */
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fprintf (stream, "\n%-17s%10s %16s %10s\n", "RTX",
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"Number", "Bytes", "% Total");
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for (code = 0; code < NUM_RTX_CODE; ++code)
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if (ggc_stats->num_rtxs[code])
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{
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fprintf (stream, "%-17s%10u%16ld%c %10.3f\n",
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rtx_name[code],
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ggc_stats->num_rtxs[code],
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SCALE (ggc_stats->size_rtxs[code]),
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LABEL (ggc_stats->size_rtxs[code]),
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(100 * ((double) ggc_stats->size_rtxs[code])
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/ ggc_stats->total_size_rtxs));
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}
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fprintf (stream,
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"%-17s%10u%16ld%c\n", "Total",
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ggc_stats->total_num_rtxs,
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SCALE (ggc_stats->total_size_rtxs),
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LABEL (ggc_stats->total_size_rtxs));
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/* Don't gather statistics any more. */
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ggc_stats = NULL;
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}
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/* Modify the bound based on rlimits. Keep the smallest number found. */
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static double
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ggc_rlimit_bound (limit)
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double limit;
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{
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#if defined(HAVE_GETRLIMIT)
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struct rlimit rlim;
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# ifdef RLIMIT_RSS
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if (getrlimit (RLIMIT_RSS, &rlim) == 0
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&& rlim.rlim_cur != (rlim_t) RLIM_INFINITY
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&& rlim.rlim_cur < limit)
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limit = rlim.rlim_cur;
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# endif
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# ifdef RLIMIT_DATA
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if (getrlimit (RLIMIT_DATA, &rlim) == 0
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&& rlim.rlim_cur != (rlim_t) RLIM_INFINITY
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&& rlim.rlim_cur < limit)
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limit = rlim.rlim_cur;
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# endif
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# ifdef RLIMIT_AS
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if (getrlimit (RLIMIT_AS, &rlim) == 0
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&& rlim.rlim_cur != (rlim_t) RLIM_INFINITY
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&& rlim.rlim_cur < limit)
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limit = rlim.rlim_cur;
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# endif
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#endif /* HAVE_GETRLIMIT */
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return limit;
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}
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/* Heuristic to set a default for GGC_MIN_EXPAND. */
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int
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ggc_min_expand_heuristic()
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{
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double min_expand = physmem_total();
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/* Adjust for rlimits. */
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min_expand = ggc_rlimit_bound (min_expand);
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/* The heuristic is a percentage equal to 30% + 70%*(RAM/1GB), yielding
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a lower bound of 30% and an upper bound of 100% (when RAM >= 1GB). */
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min_expand /= 1024*1024*1024;
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min_expand *= 70;
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min_expand = MIN (min_expand, 70);
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min_expand += 30;
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return min_expand;
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}
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/* Heuristic to set a default for GGC_MIN_HEAPSIZE. */
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int
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ggc_min_heapsize_heuristic()
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{
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double min_heap_kbytes = physmem_total();
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/* Adjust for rlimits. */
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min_heap_kbytes = ggc_rlimit_bound (min_heap_kbytes);
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min_heap_kbytes /= 1024; /* convert to Kbytes. */
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/* The heuristic is RAM/8, with a lower bound of 4M and an upper
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bound of 128M (when RAM >= 1GB). */
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min_heap_kbytes /= 8;
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min_heap_kbytes = MAX (min_heap_kbytes, 4 * 1024);
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min_heap_kbytes = MIN (min_heap_kbytes, 128 * 1024);
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return min_heap_kbytes;
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}
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void
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init_ggc_heuristics ()
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{
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#ifndef ENABLE_GC_ALWAYS_COLLECT
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set_param_value ("ggc-min-expand", ggc_min_expand_heuristic());
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set_param_value ("ggc-min-heapsize", ggc_min_heapsize_heuristic());
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#endif
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}
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