[Bug middle-end/55235] [4.8 Regression] FAIL: gcc.target/i386/pr44948-2a.c

["ubizjak at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55235

--- Comment #3 from Uros Bizjak <ubizjak at gmail dot com> 2012-11-07 19:05:33 UTC ---
It looks to me that this is the problematic change:

--- trunk/gcc/expr.c    2012/10/20 20:16:27    192640
+++ trunk/gcc/expr.c    2012/10/20 21:00:23    192641

(...)

@@ -5225,21 +5244,26 @@
      supposed to be bit-copied or bit-initialized.  */
       && expr_size (exp) != const0_rtx)
     {
-      if (GET_MODE (temp) != GET_MODE (target)
-      && GET_MODE (temp) != VOIDmode)
+      if (GET_MODE (temp) != GET_MODE (target) && GET_MODE (temp) != VOIDmode)
     {
-      int unsignedp = TYPE_UNSIGNED (TREE_TYPE (exp));
-      if (GET_MODE (target) == BLKmode
-          && GET_MODE (temp) == BLKmode)
-        emit_block_move (target, temp, expr_size (exp),
-                 (call_param_p
-                  ? BLOCK_OP_CALL_PARM
-                  : BLOCK_OP_NORMAL));
-      else if (GET_MODE (target) == BLKmode)
-        store_bit_field (target, INTVAL (expr_size (exp)) * BITS_PER_UNIT,
-                 0, 0, 0, GET_MODE (temp), temp);
+      if (GET_MODE (target) == BLKmode)
+        {
+          if (REG_P (temp))
+            {
+          if (TREE_CODE (exp) == CALL_EXPR)
+            copy_blkmode_from_reg (target, temp, TREE_TYPE (exp));
+          else
+            store_bit_field (target,
+                     INTVAL (expr_size (exp)) * BITS_PER_UNIT,
+                     0, 0, 0, GET_MODE (temp), temp);
+        }
+          else
+        emit_block_move (target, temp, expr_size (exp),
+                 (call_param_p
+                  ? BLOCK_OP_CALL_PARM : BLOCK_OP_NORMAL));
+        }

emit_block_move was guarded with BLKmode guard on both operands, all other went
through store_bit_field.