bugs/warnings fixed in lf_alloc-pin.c:

1. available_stack_size() was getting the direction wrong,
   so alloca() was never used
2. (char*) casts added to kill "break strict-aliasing rules" warnings
3. s/node/node=0/ to kill "pointer casted to integer" warning
4. added volatiles as appropriate to prevent gcc from moving
   assignment out of the loop


mysys/lf_alloc-pin.c:
  bugs/warnings fixed:
  1. available_stack_size() was getting the direction wrong,
     so alloca() was never used
  2. (char*) casts added to kill "break strict-aliasing rules" warnings
  3. s/node/node=0/ to kill "pointer casted to integer" warning
  4. added volatiles as appropriate to prevent gcc from moving
     assignment out of the loop

mysys/lf_alloc-pin.c

@@ -318,9 +318,9 @@ static int match_pins(LF_PINS *el, void *addr)
 }
 
 #if STACK_DIRECTION < 0
-#define available_stack_size(END,CUR) (long) ((char*)(CUR) - (char*)(END))
+#define available_stack_size(CUR,END) (long) ((char*)(CUR) - (char*)(END))
 #else
-#define available_stack_size(END,CUR) (long) ((char*)(END) - (char*)(CUR))
+#define available_stack_size(CUR,END) (long) ((char*)(END) - (char*)(CUR))
 #endif
 
 /*
@@ -413,15 +413,16 @@ LF_REQUIRE_PINS(1);
     first->el->el->....->el->last. Use first==last to free only one element.
 */
 static void alloc_free(struct st_lf_alloc_node *first,
-                       struct st_lf_alloc_node *last,
+                       struct st_lf_alloc_node volatile *last,
                        LF_ALLOCATOR *allocator)
 {
-  struct st_lf_alloc_node *tmp;
+  struct st_lf_alloc_node * volatile tmp;
   tmp= allocator->top;
   do
   {
     last->next= tmp;
-  } while (!my_atomic_casptr((void **)&allocator->top, (void **)&tmp, first) &&
+  } while (!my_atomic_casptr((void **)(char *)&allocator->top,
+                             (void **)(char *)&tmp, first) &&
            LF_BACKOFF);
 }
 
@@ -494,12 +495,13 @@ void *_lf_alloc_new(LF_PINS *pins)
     {
       node= (void *)my_malloc(allocator->element_size, MYF(MY_WME));
 #ifdef MY_LF_EXTRA_DEBUG
-      if (likely(node))
+      if (likely(node != 0))
         my_atomic_add32(&allocator->mallocs, 1);
 #endif
       break;
     }
-    if (my_atomic_casptr((void **)&allocator->top, (void *)&node, node->next))
+    if (my_atomic_casptr((void **)(char *)&allocator->top,
+                         (void *)&node, node->next))
       break;
   }
   _lf_unpin(pins, 0);