cselib.c (cselib_init): Use special MEM rtx form for callmem.

	* cselib.c (cselib_init): Use special MEM rtx form for callmem.
	* alias.c (canon_true_dependence): Update comment.

From-SVN: r119358

gcc/ChangeLog

 2006-11-30  Steven Bosscher  <steven@gcc.gnu.org>
 
+	* cselib.c (cselib_init): Use special MEM rtx form for callmem.
+	* alias.c (canon_true_dependence): Update comment.
+
+2006-11-30  Steven Bosscher  <steven@gcc.gnu.org>
+
 	* cgraphunit.c (cgraph_finalize_compilation_unit): Add a newline
 	at the end of a diagnostics message.
 

gcc/alias.c

@@ -2151,7 +2151,7 @@ true_dependence (rtx mem, enum machine_mode mem_mode, rtx x,
     return 1;
 
   /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
-     This is used in epilogue deallocation functions.  */
+     This is used in epilogue deallocation functions, and in cselib.  */
   if (GET_MODE (x) == BLKmode && GET_CODE (XEXP (x, 0)) == SCRATCH)
     return 1;
   if (GET_MODE (mem) == BLKmode && GET_CODE (XEXP (mem, 0)) == SCRATCH)

gcc/cselib.c

@@ -1473,9 +1473,11 @@ cselib_init (bool record_memory)
 				       sizeof (cselib_val), 10);
   value_pool = create_alloc_pool ("value", RTX_CODE_SIZE (VALUE), 100);
   cselib_record_memory = record_memory;
-  /* This is only created once.  */
+
+  /* (mem:BLK (scratch)) is a special mechanism to conflict with everything,
+     see canon_true_dependence.  This is only created once.  */
   if (! callmem)
-    callmem = gen_rtx_MEM (BLKmode, const0_rtx);
+    callmem = gen_rtx_MEM (BLKmode, gen_rtx_SCRATCH (VOIDmode));
 
   cselib_nregs = max_reg_num ();