re PR debug/50826 (bootstrap on 64 bit pa broken by r180194, ICE in mem_loc_descriptor)

PR debug/50826
* var-tracking.c (rtx_debug_expr_p): New.
(use_type): Don't use debug exprs to track non-VTA variables.

From-SVN: r180525

gcc/ChangeLog

+2011-10-26  Alexandre Oliva  <aoliva@redhat.com>
+
+	PR debug/50826
+	* var-tracking.c (rtx_debug_expr_p): New.
+	(use_type): Don't use debug exprs to track non-VTA variables.
+
 2011-10-26  Jeff Law  <law@redhat.com>
 
 	* doc/invoke.texi (sink-frequency-threshold): Document.

gcc/var-tracking.c

@@ -4907,6 +4907,18 @@ replace_expr_with_values (rtx loc)
     return cselib_subst_to_values (loc, VOIDmode);
 }
 
+/* Return true if *X is a DEBUG_EXPR.  Usable as an argument to
+   for_each_rtx to tell whether there are any DEBUG_EXPRs within
+   RTX.  */
+
+static int
+rtx_debug_expr_p (rtx *x, void *data ATTRIBUTE_UNUSED)
+{
+  rtx loc = *x;
+
+  return GET_CODE (loc) == DEBUG_EXPR;
+}
+
 /* Determine what kind of micro operation to choose for a USE.  Return
    MO_CLOBBER if no micro operation is to be generated.  */
 
@@ -4988,7 +5000,13 @@ use_type (rtx loc, struct count_use_info *cui, enum machine_mode *modep)
       else if (target_for_debug_bind (var_debug_decl (expr)))
 	return MO_CLOBBER;
       else if (track_loc_p (loc, expr, INT_MEM_OFFSET (loc),
-			    false, modep, NULL))
+			    false, modep, NULL)
+	       /* Multi-part variables shouldn't refer to one-part
+		  variable names such as VALUEs (never happens) or
+		  DEBUG_EXPRs (only happens in the presence of debug
+		  insns).  */
+	       && (!MAY_HAVE_DEBUG_INSNS
+		   || !for_each_rtx (&XEXP (loc, 0), rtx_debug_expr_p, NULL)))
 	return MO_USE;
       else
 	return MO_CLOBBER;