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");
40 type = mdp->heapinfo[block].type;
43 case -1: /* Already free */
45 THROWF(system_error, 0, "Asked to free a fragment in a block that is already free. I'm puzzled\n");
49 /* Get as many statistics as early as we can. */
50 mdp -> heapstats.chunks_used--;
51 mdp -> heapstats.bytes_used -=
52 mdp -> heapinfo[block].busy_block.size * BLOCKSIZE;
53 mdp -> heapstats.bytes_free +=
54 mdp -> heapinfo[block].busy_block.size * BLOCKSIZE;
56 /* Find the free cluster previous to this one in the free list.
57 Start searching at the last block referenced; this may benefit
58 programs with locality of allocation. */
62 i = mdp->heapinfo[i].free_block.prev;
66 i = mdp->heapinfo[i].free_block.next;
68 while ((i != 0) && (i < block));
69 i = mdp->heapinfo[i].free_block.prev;
72 /* Determine how to link this block into the free list. */
73 if (block == i + mdp->heapinfo[i].free_block.size) {
75 /* Coalesce this block with its predecessor. */
76 mdp->heapinfo[i].free_block.size += mdp->heapinfo[block].busy_block.size;
77 /* Mark all my ex-blocks as free */
78 for (it=0; it<mdp->heapinfo[block].busy_block.size; it++) {
79 if (mdp->heapinfo[block+it].type <0) {
80 fprintf(stderr,"Internal Error: Asked to free a block already marked as free (block=%lu it=%d type=%lu). Please report this bug.\n",
81 (unsigned long)block,it,(unsigned long)mdp->heapinfo[block].type);
84 mdp->heapinfo[block+it].type = -1;
89 //fprintf(stderr,"Free block %d to %d (as a new chunck)\n",block,block+mdp->heapinfo[block].busy_block.size);
90 /* Really link this block back into the free list. */
91 mdp->heapinfo[block].free_block.size = mdp->heapinfo[block].busy_block.size;
92 mdp->heapinfo[block].free_block.next = mdp->heapinfo[i].free_block.next;
93 mdp->heapinfo[block].free_block.prev = i;
94 mdp->heapinfo[i].free_block.next = block;
95 mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.prev = block;
96 mdp -> heapstats.chunks_free++;
97 /* Mark all my ex-blocks as free */
98 for (it=0; it<mdp->heapinfo[block].free_block.size; it++) {
99 if (mdp->heapinfo[block+it].type <0) {
100 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",
101 (unsigned long)block,it,(unsigned long)mdp->heapinfo[block].free_block.size,(unsigned long)mdp->heapinfo[block].type);
104 mdp->heapinfo[block+it].type = -1;
108 /* Now that the block is linked in, see if we can coalesce it
109 with its successor (by deleting its successor from the list
110 and adding in its size). */
111 if (block + mdp->heapinfo[block].free_block.size ==
112 mdp->heapinfo[block].free_block.next) {
113 mdp->heapinfo[block].free_block.size
114 += mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.size;
115 mdp->heapinfo[block].free_block.next
116 = mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.next;
117 mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.prev = block;
118 mdp -> heapstats.chunks_free--;
121 /* Now see if we can return stuff to the system. */
122 /* blocks = mdp -> heapinfo[block].free.size;
123 if (blocks >= FINAL_FREE_BLOCKS && block + blocks == mdp -> heaplimit
124 && mdp -> morecore (mdp, 0) == ADDRESS (block + blocks))
126 register size_t bytes = blocks * BLOCKSIZE;
127 mdp -> heaplimit -= blocks;
128 mdp -> morecore (mdp, -bytes);
129 mdp -> heapinfo[mdp -> heapinfo[block].free.prev].free.next
130 = mdp -> heapinfo[block].free.next;
131 mdp -> heapinfo[mdp -> heapinfo[block].free.next].free.prev
132 = mdp -> heapinfo[block].free.prev;
133 block = mdp -> heapinfo[block].free.prev;
134 mdp -> heapstats.chunks_free--;
135 mdp -> heapstats.bytes_free -= bytes;
138 /* Set the next search to begin at this block.
139 This is probably important to the trick where realloc returns the block to
140 the system before reasking for the same block with a bigger size. */
141 mdp->heapindex = block;
145 /* Do some of the statistics. */
146 mdp -> heapstats.chunks_used--;
147 mdp -> heapstats.bytes_used -= 1 << type;
148 mdp -> heapstats.chunks_free++;
149 mdp -> heapstats.bytes_free += 1 << type;
151 /* Get the address of the first free fragment in this block. */
152 prev = (struct list *)
153 ((char *) ADDRESS(block) +
154 (mdp->heapinfo[block].busy_frag.first << type));
156 frag_nb = RESIDUAL(ptr, BLOCKSIZE) >> type;
158 if( mdp->heapinfo[block].busy_frag.frag_size[frag_nb] == -1){
160 THROWF(system_error, 0, "Asked to free a fragment that is already free. I'm puzzled\n");
163 /* Set size used in the fragment to -1 */
164 mdp->heapinfo[block].busy_frag.frag_size[frag_nb] = -1;
166 if (mdp->heapinfo[block].busy_frag.nfree ==
167 (BLOCKSIZE >> type) - 1) {
168 /* If all fragments of this block are free, remove them
169 from the fragment list and free the whole block. */
171 for (i = 1; i < (size_t) (BLOCKSIZE >> type); ++i) {
174 prev->prev->next = next;
176 next->prev = prev->prev;
178 /* pretend that this block is used and free it so that it gets properly coalesced with adjacent free blocks */
179 mdp->heapinfo[block].type = 0;
180 mdp->heapinfo[block].busy_block.size = 1;
181 mdp->heapinfo[block].busy_block.busy_size = 0;
183 /* Keep the statistics accurate. */
184 mdp -> heapstats.chunks_used++;
185 mdp -> heapstats.bytes_used += BLOCKSIZE;
186 mdp -> heapstats.chunks_free -= BLOCKSIZE >> type;
187 mdp -> heapstats.bytes_free -= BLOCKSIZE;
189 mfree((void *) mdp, (void *) ADDRESS(block));
190 } else if (mdp->heapinfo[block].busy_frag.nfree != 0) {
191 /* If some fragments of this block are free, link this
192 fragment into the fragment list after the first free
193 fragment of this block. */
194 next = (struct list *) ptr;
195 next->next = prev->next;
198 if (next->next != NULL) {
199 next->next->prev = next;
201 ++mdp->heapinfo[block].busy_frag.nfree;
203 /* No fragments of this block were free before the one we just released,
204 * so link this fragment into the fragment list and announce that
205 it is the first free fragment of this block. */
206 prev = (struct list *) ptr;
207 mdp->heapinfo[block].busy_frag.nfree = 1;
208 mdp->heapinfo[block].busy_frag.first = frag_nb;
209 prev->next = mdp->fraghead[type].next;
210 prev->prev = &mdp->fraghead[type];
211 prev->prev->next = prev;
212 if (prev->next != NULL) {
213 prev->next->prev = prev;