sys_alloc.c: previous_size should not be declared/used on every case.

src/sys_alloc.c

@@ -44,8 +44,11 @@ static int dev_zero_fd = -1; /* Cached file descriptor for /dev/zero. */
 
 void *sys_alloc(allocator_t *allocator, heap_t *heap, size_t size) {
 
-    size_t allocation_size, previous_size, previous_size_availability;
+    size_t allocation_size, previous_size_availability;
     void *ptr;
+#if defined (WITH_MEMORY_SPACE_AWARENESS) || (!defined (WITH_MEMORY_SPACE_AWARENESS) && (defined (COALESCING_FIXED) || defined (COALESCING_VARIABLE)))
+    size_t previous_size;
+#endif /* check if previous_size is needed */
 #ifdef WITH_MMAP
     int fd;
 #endif /* WITH_MMAP */
@@ -62,16 +65,20 @@ void *sys_alloc(allocator_t *allocator, heap_t *heap, size_t size) {
      */
 #ifndef WITH_MEMORY_SPACE_AWARENESS
     if(allocator->border_ptr != NULL) {
+#if defined (COALESCING_FIXED) || defined (COALESCING_VARIABLE) 
+        previous_size = get_size(allocator->border_ptr);
+#endif /* COALESCING_FIXED || COALESCING_VARIABLE */
 #else
     /* Note: border_ptr has already a value in memory space aware allocators,
      * so in this case we have to check also the initialized value.
      */
     if(allocator->border_ptr != NULL && allocator->initialized) {
 #endif /* WITH_MEMORY_SPACE_AWARENESS */
-        previous_size = get_size(allocator->border_ptr);
         previous_size_availability = get_size_availability(allocator->border_ptr);
     } else {
+#if defined (WITH_MEMORY_SPACE_AWARENESS) || (!defined (WITH_MEMORY_SPACE_AWARENESS) && (defined (COALESCING_FIXED) || defined (COALESCING_VARIABLE)))
         previous_size = 0;
+#endif /* check if previous_size is needed */
         previous_size_availability = 1; /* Occupied and of 0 size */
         allocator->initialized = true;
     }