1 /* Free a block of memory allocated by `mmalloc'.
2 Copyright 1990, 1991, 1992 Free Software Foundation
4 Written May 1989 by Mike Haertel.
5 Heavily modified Mar 1992 by Fred Fish. (fnf@cygnus.com) */
7 /* Copyright (c) 2010. The SimGrid Team.
8 * All rights reserved. */
10 /* This program is free software; you can redistribute it and/or modify it
11 * under the terms of the license (GNU LGPL) which comes with this package. */
13 #include "mmprivate.h"
15 /* Return memory to the heap.
16 Like `mfree' but don't call a mfree_hook if there is one. */
18 /* Return memory to the heap. */
19 void mfree(struct mdesc *mdp, void *ptr)
24 struct list *prev, *next;
32 if ((char *) ptr < (char *) mdp->heapbase || block > mdp->heapsize) {
33 fprintf(stderr,"Ouch, this pointer is not mine. I refuse to free it. I refuse it to death!!\n");
38 type = mdp->heapinfo[block].type;
41 case -1: /* Already free */
42 fprintf(stderr,"Asked to free a fragment in a block that is already free. I'm puzzled\n");
47 /* Get as many statistics as early as we can. */
48 mdp -> heapstats.chunks_used--;
49 mdp -> heapstats.bytes_used -=
50 mdp -> heapinfo[block].busy_block.size * BLOCKSIZE;
51 mdp -> heapstats.bytes_free +=
52 mdp -> heapinfo[block].busy_block.size * BLOCKSIZE;
54 /* Find the free cluster previous to this one in the free list.
55 Start searching at the last block referenced; this may benefit
56 programs with locality of allocation. */
60 i = mdp->heapinfo[i].free_block.prev;
64 i = mdp->heapinfo[i].free_block.next;
66 while ((i != 0) && (i < block));
67 i = mdp->heapinfo[i].free_block.prev;
70 /* Determine how to link this block into the free list. */
71 if (block == i + mdp->heapinfo[i].free_block.size) {
73 /* Coalesce this block with its predecessor. */
74 mdp->heapinfo[i].free_block.size += mdp->heapinfo[block].busy_block.size;
75 /* Mark all my ex-blocks as free */
76 for (it=0; it<mdp->heapinfo[block].busy_block.size; it++) {
77 if (mdp->heapinfo[block+it].type <0) {
78 fprintf(stderr,"Internal Error: Asked to free a block already marked as free (block=%lu it=%d type=%lu). Please report this bug.\n",
79 (unsigned long)block,it,(unsigned long)mdp->heapinfo[block].type);
82 mdp->heapinfo[block+it].type = -1;
87 //fprintf(stderr,"Free block %d to %d (as a new chunck)\n",block,block+mdp->heapinfo[block].busy_block.size);
88 /* Really link this block back into the free list. */
89 mdp->heapinfo[block].free_block.size = mdp->heapinfo[block].busy_block.size;
90 mdp->heapinfo[block].free_block.next = mdp->heapinfo[i].free_block.next;
91 mdp->heapinfo[block].free_block.prev = i;
92 mdp->heapinfo[i].free_block.next = block;
93 mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.prev = block;
94 mdp -> heapstats.chunks_free++;
95 /* Mark all my ex-blocks as free */
96 for (it=0; it<mdp->heapinfo[block].free_block.size; it++) {
97 if (mdp->heapinfo[block+it].type <0) {
98 fprintf(stderr,"Internal error: Asked to free a block already marked as free (block=%lu it=%d/%lu type=%lu). Please report this bug.\n",
99 (unsigned long)block,it,(unsigned long)mdp->heapinfo[block].free_block.size,(unsigned long)mdp->heapinfo[block].type);
102 mdp->heapinfo[block+it].type = -1;
106 /* Now that the block is linked in, see if we can coalesce it
107 with its successor (by deleting its successor from the list
108 and adding in its size). */
109 if (block + mdp->heapinfo[block].free_block.size ==
110 mdp->heapinfo[block].free_block.next) {
111 mdp->heapinfo[block].free_block.size
112 += mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.size;
113 mdp->heapinfo[block].free_block.next
114 = mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.next;
115 mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.prev = block;
116 mdp -> heapstats.chunks_free--;
119 /* Now see if we can return stuff to the system. */
120 /* blocks = mdp -> heapinfo[block].free.size;
121 if (blocks >= FINAL_FREE_BLOCKS && block + blocks == mdp -> heaplimit
122 && mdp -> morecore (mdp, 0) == ADDRESS (block + blocks))
124 register size_t bytes = blocks * BLOCKSIZE;
125 mdp -> heaplimit -= blocks;
126 mdp -> morecore (mdp, -bytes);
127 mdp -> heapinfo[mdp -> heapinfo[block].free.prev].free.next
128 = mdp -> heapinfo[block].free.next;
129 mdp -> heapinfo[mdp -> heapinfo[block].free.next].free.prev
130 = mdp -> heapinfo[block].free.prev;
131 block = mdp -> heapinfo[block].free.prev;
132 mdp -> heapstats.chunks_free--;
133 mdp -> heapstats.bytes_free -= bytes;
136 /* Set the next search to begin at this block. */
137 mdp->heapindex = block;
141 /* Do some of the statistics. */
142 mdp -> heapstats.chunks_used--;
143 mdp -> heapstats.bytes_used -= 1 << type;
144 mdp -> heapstats.chunks_free++;
145 mdp -> heapstats.bytes_free += 1 << type;
148 /* Get the address of the first free fragment in this block. */
149 prev = (struct list *)
150 ((char *) ADDRESS(block) +
151 (mdp->heapinfo[block].busy_frag.first << type));
153 if (mdp->heapinfo[block].busy_frag.nfree ==
154 (BLOCKSIZE >> type) - 1) {
155 /* If all fragments of this block are free, remove them
156 from the fragment list and free the whole block. */
158 for (i = 1; i < (size_t) (BLOCKSIZE >> type); ++i) {
161 prev->prev->next = next;
163 next->prev = prev->prev;
165 /* pretend that this block is used and free it so that it gets properly coalesced with adjacent free blocks */
166 mdp->heapinfo[block].type = 0;
167 mdp->heapinfo[block].busy_block.size = 1;
168 mdp->heapinfo[block].busy_block.busy_size = 0;
170 /* Keep the statistics accurate. */
171 mdp -> heapstats.chunks_used++;
172 mdp -> heapstats.bytes_used += BLOCKSIZE;
173 mdp -> heapstats.chunks_free -= BLOCKSIZE >> type;
174 mdp -> heapstats.bytes_free -= BLOCKSIZE;
176 mfree((void *) mdp, (void *) ADDRESS(block));
177 } else if (mdp->heapinfo[block].busy_frag.nfree != 0) {
178 /* If some fragments of this block are free, link this
179 fragment into the fragment list after the first free
180 fragment of this block. */
181 next = (struct list *) ptr;
182 next->next = prev->next;
185 if (next->next != NULL) {
186 next->next->prev = next;
188 ++mdp->heapinfo[block].busy_frag.nfree;
190 /* No fragments of this block were free before the one we just released,
191 * so link this fragment into the fragment list and announce that
192 it is the first free fragment of this block. */
193 prev = (struct list *) ptr;
194 mdp->heapinfo[block].busy_frag.nfree = 1;
195 mdp->heapinfo[block].busy_frag.first =
196 RESIDUAL(ptr, BLOCKSIZE) >> type;
197 prev->next = mdp->fraghead[type].next;
198 prev->prev = &mdp->fraghead[type];
199 prev->prev->next = prev;
200 if (prev->next != NULL) {
201 prev->next->prev = prev;