(extract_bit_field): Check TRULY_NOOP_TRUNCATION before

making a SUBREG of a REG.

From-SVN: r12338

diff --git a/gcc/expmed.c b/gcc/expmed.c
index be27f855ae84011130696f2f85cc2a773e5cac93..a59394230348c1804a92f2dc7df9439402cb765f 100644 (file)
--- a/gcc/expmed.c
+++ b/gcc/expmed.c
@@ -928,7 +928,9 @@ extract_bit_field (str_rtx, bitsize, bitnum, unsignedp,
      So too extracting a subword value in
      the least significant part of the register.  */
 
-  if ((GET_CODE (op0) == REG
+  if (((GET_CODE (op0) == REG
+       && TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (mode),
+                                 GET_MODE_BITSIZE (GET_MODE (op0))))
        || (GET_CODE (op0) == MEM
           && (! SLOW_UNALIGNED_ACCESS
               || (offset * BITS_PER_UNIT % bitsize == 0