expmed.c (extract_bit_field_1): Avoid clobbering a yet-to-be-used base/index register.

* expmed.c (extract_bit_field_1): Avoid clobbering a
yet-to-be-used base/index register.

From-SVN: r223885

gcc/ChangeLog

+2015-05-28  DJ Delorie  <dj@redhat.com>
+
+	* expmed.c (extract_bit_field_1): Avoid clobbering a
+	yet-to-be-used base/index register.
+
 2015-05-30  Jan Hubicka  <hubicka@ucw.cz>
 
 	* alias.c (alias_set_entry_d): Add is_pointer and has_pointer.

gcc/expmed.c

@@ -1616,6 +1616,11 @@ extract_bit_field_1 (rtx str_rtx, unsigned HOST_WIDE_INT bitsize,
       if (target == 0 || !REG_P (target) || !valid_multiword_target_p (target))
 	target = gen_reg_rtx (mode);
 
+      /* In case we're about to clobber a base register or something 
+	 (see gcc.c-torture/execute/20040625-1.c).   */
+      if (reg_mentioned_p (target, str_rtx))
+	target = gen_reg_rtx (mode);
+
       /* Indicate for flow that the entire target reg is being set.  */
       emit_clobber (target);