Mark variables addressable if they are copied using libcall in RTL expander

[Easwaran Raman]

This fixes bugs introduced by r175063. OK for trunk if there are no
test regressions?

-Easwaran


2011-06-20  Easwaran Raman  <era...@google.com>

        PR rtl-optimization/49429
        * expr.c (emit_block_move_hints):  Mark MEM_EXPR(x) and
        MEM_EXPR(y) addressable if emit_block_move_via_libcall is
        used to copy y into x.

Index: gcc/expr.c
===================================================================
--- gcc/expr.c  (revision 175081)
+++ gcc/expr.c  (working copy)
@@ -1181,8 +1181,19 @@ emit_block_move_hints (rtx x, rtx y, rtx size, enu
   else if (may_use_call
           && ADDR_SPACE_GENERIC_P (MEM_ADDR_SPACE (x))
           && ADDR_SPACE_GENERIC_P (MEM_ADDR_SPACE (y)))
-    retval = emit_block_move_via_libcall (x, y, size,
-                                         method == BLOCK_OP_TAILCALL);
+    {
+      /* Since x and y are passed to a libcall, mark the corresponding
+         tree EXPR as addressable.  */
+      tree y_expr = MEM_EXPR (y);
+      tree x_expr = MEM_EXPR (x);
+      if (y_expr)
+        mark_addressable (y_expr);
+      if (x_expr)
+        mark_addressable (x_expr);
+      retval = emit_block_move_via_libcall (x, y, size,
+                                           method == BLOCK_OP_TAILCALL);
+    }
+
   else
     emit_block_move_via_loop (x, y, size, align);