diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 8af4967c718346a28004cfbb3cf1ebfdd9235576..b12b46590c6ce0a87134cc4e6d4fea5b84116814 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2013-02-03  Richard Sandiford  <rdsandiford@googlemail.com>
+
+	* expmed.c (extract_bit_field_1): Pass the full width of the
+	structure to get_best_reg_extraction_insn.
+
 2013-02-01  David Edelsohn  <dje.gcc@gmail.com>
 
 	PR target/54601
diff --git a/gcc/expmed.c b/gcc/expmed.c
index da37e6b81850c9bd1042924256d2e2ef55c4eb6f..4a6ddb06b1105f68ffaac17d1c15dd555c957d8c 100644
--- a/gcc/expmed.c
+++ b/gcc/expmed.c
@@ -1569,7 +1569,11 @@ extract_bit_field_1 (rtx str_rtx, unsigned HOST_WIDE_INT bitsize,
   enum extraction_pattern pattern = unsignedp ? EP_extzv : EP_extv;
   extraction_insn extv;
   if (!MEM_P (op0)
-      && get_best_reg_extraction_insn (&extv, pattern, bitnum + bitsize,
+      /* ??? We could limit the structure size to the part of OP0 that
+	 contains the field, with appropriate checks for endianness
+	 and TRULY_NOOP_TRUNCATION.  */
+      && get_best_reg_extraction_insn (&extv, pattern,
+				       GET_MODE_BITSIZE (GET_MODE (op0)),
 				       tmode))
     {
       rtx result = extract_bit_field_using_extv (&extv, op0, bitsize, bitnum,