diff: memory allocation bug fix

[Fergus Henderson]

Estimated hours taken: 6

Fix a memory allocation bug reported by
Warwick Harvey <wharvey at cs.monash.edu.au>.

library/std_util.m:
runtime/mercury_type_info.c:
	Use `newmem()' rather than `malloc()' when allocating memory
	that will contain Mercury terms or types.  This is needed
	because the Boehm collector does not trace memory allocated
	with malloc().

Index: library/std_util.m
===================================================================
RCS file: /home/mercury1/repository/mercury/library/std_util.m,v
retrieving revision 1.139
diff -u -r1.139 std_util.m
--- std_util.m	1999/01/05 17:05:06	1.139
+++ std_util.m	1999/01/28 11:42:25
@@ -2174,9 +2174,13 @@
 ** Expand the given data using its type_info, find its
 ** functor, arity, argument vector and type_info vector.
 ** 
-** The info.type_info_vector is allocated using malloc 
-** It is the responsibility of the  caller to free this
-** memory, and to copy any fields of this vector to
+** The info.type_info_vector is allocated using newmem().
+** (We need to use newmem() rather than malloc(), since this
+** vector may contain pointers into the Mercury heap, and
+** memory allocated with malloc will not be traced by the
+** Boehm collector.)
+** It is the responsibility of the  caller to deallocate this
+** memory (using oldmem()), and to copy any fields of this vector to
 ** the Mercury heap. The type_infos that the elements of
 ** this vector point to are either
 ** 	- already allocated on the heap.
@@ -2281,8 +2285,7 @@
             if (info->need_args) {
                 info->argument_vector = (Word *) data_value;
 
-                info->type_info_vector = checked_malloc(
-                    info->arity * sizeof(Word));
+                info->type_info_vector = newmem(info->arity * sizeof(Word));
 
                 for (i = 0; i < info->arity ; i++) {
                     Word *arg_pseudo_type_info;
@@ -2319,8 +2322,7 @@
                      */
                 info->argument_vector = (Word *) data_word_ptr;
 
-                info->type_info_vector = checked_malloc(
-                    info->arity * sizeof(Word));
+                info->type_info_vector = newmem(info->arity * sizeof(Word));
 
                 for (i = 0; i < info->arity ; i++) {
                     Word *arg_pseudo_type_info;
@@ -2529,7 +2531,7 @@
 	** Free the allocated type_info_vector, since we just copied
 	** the stuff we want out of it.
 	*/
-	free(info.type_info_vector);
+	oldmem(info.type_info_vector);
 
 	return success;
 }
@@ -2726,7 +2728,7 @@
 	 * all its arguments onto the heap. 
 	 */
 
-	free(info.type_info_vector);
+	oldmem(info.type_info_vector);
 
 }").
 
Index: runtime/mercury_type_info.c
===================================================================
RCS file: /home/mercury1/repository/mercury/runtime/mercury_type_info.c,v
retrieving revision 1.14
diff -u -r1.14 mercury_type_info.c
--- mercury_type_info.c	1998/11/11 02:14:19	1.14
+++ mercury_type_info.c	1999/01/28 11:44:50
@@ -173,7 +173,7 @@
 	**
 	** NOTE: If you are changing this code, you might also need
 	** to change the code in MR_make_type_info in this module 
-	** which does much the same thing, only allocating using malloc
+	** which does much the same thing, only allocating using newmem
 	** instead of on the heap.
 	*/
 
@@ -409,8 +409,8 @@
 {
 	while (allocated != NULL) {
 		MR_MemoryList next = allocated->next;
-		free(allocated->data);
-		free(allocated);
+		oldmem(allocated->data);
+		oldmem(allocated);
 		allocated = next;
 	}
 }
@@ -430,19 +430,22 @@
 	** arg_pseudo_type_info with all the type variables filled in.
 	** If there are no type variables to fill in, we return the
 	** arg_pseudo_type_info, unchanged. Otherwise, we allocate
-	** memory using malloc().  Any such memory allocated will be
+	** memory using newmem().  Any such memory allocated will be
 	** inserted into the list of allocated memory cells.
 	** It is the caller's responsibility to free these cells
 	** by calling MR_deallocate() on the list when they are no longer
 	** needed.
 	**
 	** This code could be tighter. In general, we want to
-	** handle our own allocations rather than using malloc().
+	** handle our own allocations rather than using newmem().
+	** (Note: we need to use newmem() rather than malloc()
+	** because the Boehm collector doesn't trace memory
+	** allocated with malloc().)
 	**
 	** NOTE: If you are changing this code, you might also need
 	** to change the code in MR_create_type_info (defined above),
 	** which does much the same thing, only allocating on the 
-	** heap instead of using malloc.
+	** heap instead of using newmem.
 	*/
 
 Word *
@@ -507,9 +510,9 @@
 				MR_MemoryList node;
 				/*
 				** allocate a new type_info and copy the
-				** data across from arg_pseduo_type_info
+				** data across from arg_pseudo_type_info
 				*/
-				type_info = checked_malloc(
+				type_info = newmem(
 					(arity + extra_args) * sizeof(Word));
 				memcpy(type_info, arg_pseudo_type_info,
 					(arity + extra_args) * sizeof(Word));
@@ -518,7 +521,7 @@
 				** list of allocated memory cells, so we can
 				** free it later on
 				*/
-				node = checked_malloc(sizeof(*node));
+				node = newmem(sizeof(*node));
 				node->data = type_info;
 				node->next = *allocated;
 				*allocated = node;

-- 
Fergus Henderson <fjh at cs.mu.oz.au>  |  "Binaries may die
WWW: <http://www.cs.mu.oz.au/~fjh>  |   but source code lives forever"
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