Remove last_cache

This patch removes global variable 'last_cache', and initialize
'target_dcache' lazily, so that 'target_dcache' can replace
'last_cache'.  No functionalities should be changed after this patch.

gdb:

2013-11-20  Yao Qi  <yao@codesourcery.com>

	* dcache.c (last_cache): Remove.
	(dcache_free, dcache_init): Update.
	(dcache_update):
	(dcache_print_line): Add parameter 'dcache'.  Replace
	'target_dcache' with 'dcache'.
	(dcache_info): Move code to dcache_info_1. Call
	'dcache_info_1'.
	(dcache_info_1): New function.
	(set_dcache_size): Call target_dcache_invalidate.
	(set_dcache_line_size): Call target_dcache_invalidate.
	* target.c (target_dcache_init_p): New function.
	(target_dcache_invalidate): Check target_dcache_init_p first.
	(target_dcache_get, target_dcache_get_or_init): New function.
	(memory_xfer_partial_1): Adjust.
	(initialize_target): Don't initialize 'target_dcache'.
	* target.h (struct dcache_struct): Declare.
	(target_dcache_get): Declare.

gdb/dcache.c

@@ -139,8 +139,6 @@ show_dcache_enabled_p (struct ui_file *file, int from_tty,
   fprintf_filtered (file, _("Deprecated remotecache flag is %s.\n"), value);
 }
 
-static DCACHE *last_cache; /* Used by info dcache.  */
-
 /* Add BLOCK to circular block list BLIST, behind the block at *BLIST.
    *BLIST is not updated (unless it was previously NULL of course).
    This is for the least-recently-allocated list's sake:
@@ -225,9 +223,6 @@ free_block (struct dcache_block *block, void *param)
 void
 dcache_free (DCACHE *dcache)
 {
-  if (last_cache == dcache)
-    last_cache = NULL;
-
   splay_tree_delete (dcache->tree);
   for_each_block (&dcache->oldest, free_block, NULL);
   for_each_block (&dcache->freelist, free_block, NULL);
@@ -468,7 +463,6 @@ dcache_init (void)
   dcache->size = 0;
   dcache->line_size = dcache_line_size;
   dcache->ptid = null_ptid;
-  last_cache = dcache;
 
   return dcache;
 }
@@ -557,26 +551,28 @@ dcache_update (DCACHE *dcache, CORE_ADDR memaddr, gdb_byte *myaddr, int len)
     dcache_poke_byte (dcache, memaddr + i, myaddr + i);
 }
 
+/* Print DCACHE line INDEX.  */
+
 static void
-dcache_print_line (int index)
+dcache_print_line (DCACHE *dcache, int index)
 {
   splay_tree_node n;
   struct dcache_block *db;
   int i, j;
 
-  if (!last_cache)
+  if (dcache == NULL)
     {
       printf_filtered (_("No data cache available.\n"));
       return;
     }
 
-  n = splay_tree_min (last_cache->tree);
+  n = splay_tree_min (dcache->tree);
 
   for (i = index; i > 0; --i)
     {
       if (!n)
 	break;
-      n = splay_tree_successor (last_cache->tree, n->key);
+      n = splay_tree_successor (dcache->tree, n->key);
     }
 
   if (!n)
@@ -590,19 +586,21 @@ dcache_print_line (int index)
   printf_filtered (_("Line %d: address %s [%d hits]\n"),
 		   index, paddress (target_gdbarch (), db->addr), db->refs);
 
-  for (j = 0; j < last_cache->line_size; j++)
+  for (j = 0; j < dcache->line_size; j++)
     {
       printf_filtered ("%02x ", db->data[j]);
 
       /* Print a newline every 16 bytes (48 characters).  */
-      if ((j % 16 == 15) && (j != last_cache->line_size - 1))
+      if ((j % 16 == 15) && (j != dcache->line_size - 1))
 	printf_filtered ("\n");
     }
   printf_filtered ("\n");
 }
 
+/* Parse EXP and show the info about DCACHE.  */
+
 static void
-dcache_info (char *exp, int tty)
+dcache_info_1 (DCACHE *dcache, char *exp)
 {
   splay_tree_node n;
   int i, refcount;
@@ -618,27 +616,27 @@ dcache_info (char *exp, int tty)
           return;
 	}
 
-      dcache_print_line (i);
+      dcache_print_line (dcache, i);
       return;
     }
 
   printf_filtered (_("Dcache %u lines of %u bytes each.\n"),
 		   dcache_size,
-		   last_cache ? (unsigned) last_cache->line_size
+		   dcache ? (unsigned) dcache->line_size
 		   : dcache_line_size);
 
-  if (!last_cache || ptid_equal (last_cache->ptid, null_ptid))
+  if (dcache == NULL || ptid_equal (dcache->ptid, null_ptid))
     {
       printf_filtered (_("No data cache available.\n"));
       return;
     }
 
   printf_filtered (_("Contains data for %s\n"),
-		   target_pid_to_str (last_cache->ptid));
+		   target_pid_to_str (dcache->ptid));
 
   refcount = 0;
 
-  n = splay_tree_min (last_cache->tree);
+  n = splay_tree_min (dcache->tree);
   i = 0;
 
   while (n)
@@ -650,12 +648,18 @@ dcache_info (char *exp, int tty)
       i++;
       refcount += db->refs;
 
-      n = splay_tree_successor (last_cache->tree, n->key);
+      n = splay_tree_successor (dcache->tree, n->key);
     }
 
   printf_filtered (_("Cache state: %d active lines, %d hits\n"), i, refcount);
 }
 
+static void
+dcache_info (char *exp, int tty)
+{
+  dcache_info_1 (target_dcache_get (), exp);
+}
+
 static void
 set_dcache_size (char *args, int from_tty,
 		 struct cmd_list_element *c)
@@ -665,8 +669,7 @@ set_dcache_size (char *args, int from_tty,
       dcache_size = DCACHE_DEFAULT_SIZE;
       error (_("Dcache size must be greater than 0."));
     }
-  if (last_cache)
-    dcache_invalidate (last_cache);
+  target_dcache_invalidate ();
 }
 
 static void
@@ -680,8 +683,7 @@ set_dcache_line_size (char *args, int from_tty,
       dcache_line_size = DCACHE_DEFAULT_LINE_SIZE;
       error (_("Invalid dcache line size: %u (must be power of 2)."), d);
     }
-  if (last_cache)
-    dcache_invalidate (last_cache);
+  target_dcache_invalidate ();
 }
 
 static void