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"
16 /* Return memory to the heap.
17 Like `mfree' but don't call a mfree_hook if there is one. */
19 /* Return memory to the heap. */
20 void mfree(struct mdesc *mdp, void *ptr)
23 size_t block, frag_nb;
25 struct list *prev, *next;
33 if ((char *) ptr < (char *) mdp->heapbase || block > mdp->heapsize) {
34 fprintf(stderr,"Ouch, this pointer is not mine. I refuse to free it. I refuse it to death!!\n");
39 type = mdp->heapinfo[block].type;
42 case -1: /* Already free */
44 THROWF(system_error, 0, "Asked to free a fragment in a block that is already free. I'm puzzled\n");
48 /* Get as many statistics as early as we can. */
49 mdp -> heapstats.chunks_used--;
50 mdp -> heapstats.bytes_used -=
51 mdp -> heapinfo[block].busy_block.size * BLOCKSIZE;
52 mdp -> heapstats.bytes_free +=
53 mdp -> heapinfo[block].busy_block.size * BLOCKSIZE;
55 /* Find the free cluster previous to this one in the free list.
56 Start searching at the last block referenced; this may benefit
57 programs with locality of allocation. */
61 i = mdp->heapinfo[i].free_block.prev;
65 i = mdp->heapinfo[i].free_block.next;
67 while ((i != 0) && (i < block));
68 i = mdp->heapinfo[i].free_block.prev;
71 /* Determine how to link this block into the free list. */
72 if (block == i + mdp->heapinfo[i].free_block.size) {
74 /* Coalesce this block with its predecessor. */
75 mdp->heapinfo[i].free_block.size += mdp->heapinfo[block].busy_block.size;
76 /* Mark all my ex-blocks as free */
77 for (it=0; it<mdp->heapinfo[block].busy_block.size; it++) {
78 if (mdp->heapinfo[block+it].type <0) {
79 fprintf(stderr,"Internal Error: Asked to free a block already marked as free (block=%lu it=%d type=%lu). Please report this bug.\n",
80 (unsigned long)block,it,(unsigned long)mdp->heapinfo[block].type);
83 mdp->heapinfo[block+it].type = -1;
88 //fprintf(stderr,"Free block %d to %d (as a new chunck)\n",block,block+mdp->heapinfo[block].busy_block.size);
89 /* Really link this block back into the free list. */
90 mdp->heapinfo[block].free_block.size = mdp->heapinfo[block].busy_block.size;
91 mdp->heapinfo[block].free_block.next = mdp->heapinfo[i].free_block.next;
92 mdp->heapinfo[block].free_block.prev = i;
93 mdp->heapinfo[i].free_block.next = block;
94 mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.prev = block;
95 mdp -> heapstats.chunks_free++;
96 /* Mark all my ex-blocks as free */
97 for (it=0; it<mdp->heapinfo[block].free_block.size; it++) {
98 if (mdp->heapinfo[block+it].type <0) {
99 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",
100 (unsigned long)block,it,(unsigned long)mdp->heapinfo[block].free_block.size,(unsigned long)mdp->heapinfo[block].type);
103 mdp->heapinfo[block+it].type = -1;
107 /* Now that the block is linked in, see if we can coalesce it
108 with its successor (by deleting its successor from the list
109 and adding in its size). */
110 if (block + mdp->heapinfo[block].free_block.size ==
111 mdp->heapinfo[block].free_block.next) {
112 mdp->heapinfo[block].free_block.size
113 += mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.size;
114 mdp->heapinfo[block].free_block.next
115 = mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.next;
116 mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.prev = block;
117 mdp -> heapstats.chunks_free--;
120 /* Now see if we can return stuff to the system. */
121 /* blocks = mdp -> heapinfo[block].free.size;
122 if (blocks >= FINAL_FREE_BLOCKS && block + blocks == mdp -> heaplimit
123 && mdp -> morecore (mdp, 0) == ADDRESS (block + blocks))
125 register size_t bytes = blocks * BLOCKSIZE;
126 mdp -> heaplimit -= blocks;
127 mdp -> morecore (mdp, -bytes);
128 mdp -> heapinfo[mdp -> heapinfo[block].free.prev].free.next
129 = mdp -> heapinfo[block].free.next;
130 mdp -> heapinfo[mdp -> heapinfo[block].free.next].free.prev
131 = mdp -> heapinfo[block].free.prev;
132 block = mdp -> heapinfo[block].free.prev;
133 mdp -> heapstats.chunks_free--;
134 mdp -> heapstats.bytes_free -= bytes;
137 /* Set the next search to begin at this block. */
138 mdp->heapindex = block;
142 /* Do some of the statistics. */
143 mdp -> heapstats.chunks_used--;
144 mdp -> heapstats.bytes_used -= 1 << type;
145 mdp -> heapstats.chunks_free++;
146 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 frag_nb = RESIDUAL(ptr, BLOCKSIZE) >> type;
155 if( mdp->heapinfo[block].busy_frag.frag_size[frag_nb] == -1){
157 THROWF(system_error, 0, "Asked to free a fragment that is already free. I'm puzzled\n");
160 /* Set size used in the fragment to -1 */
161 mdp->heapinfo[block].busy_frag.frag_size[frag_nb] = -1;
163 if (mdp->heapinfo[block].busy_frag.nfree ==
164 (BLOCKSIZE >> type) - 1) {
165 /* If all fragments of this block are free, remove them
166 from the fragment list and free the whole block. */
168 for (i = 1; i < (size_t) (BLOCKSIZE >> type); ++i) {
171 prev->prev->next = next;
173 next->prev = prev->prev;
175 /* pretend that this block is used and free it so that it gets properly coalesced with adjacent free blocks */
176 mdp->heapinfo[block].type = 0;
177 mdp->heapinfo[block].busy_block.size = 1;
178 mdp->heapinfo[block].busy_block.busy_size = 0;
180 /* Keep the statistics accurate. */
181 mdp -> heapstats.chunks_used++;
182 mdp -> heapstats.bytes_used += BLOCKSIZE;
183 mdp -> heapstats.chunks_free -= BLOCKSIZE >> type;
184 mdp -> heapstats.bytes_free -= BLOCKSIZE;
186 mfree((void *) mdp, (void *) ADDRESS(block));
187 } else if (mdp->heapinfo[block].busy_frag.nfree != 0) {
188 /* If some fragments of this block are free, link this
189 fragment into the fragment list after the first free
190 fragment of this block. */
191 next = (struct list *) ptr;
192 next->next = prev->next;
195 if (next->next != NULL) {
196 next->next->prev = next;
198 ++mdp->heapinfo[block].busy_frag.nfree;
200 /* No fragments of this block were free before the one we just released,
201 * so link this fragment into the fragment list and announce that
202 it is the first free fragment of this block. */
203 prev = (struct list *) ptr;
204 mdp->heapinfo[block].busy_frag.nfree = 1;
205 mdp->heapinfo[block].busy_frag.first = frag_nb;
206 prev->next = mdp->fraghead[type].next;
207 prev->prev = &mdp->fraghead[type];
208 prev->prev->next = prev;
209 if (prev->next != NULL) {
210 prev->next->prev = prev;