emit-rtl.c (constant_subword): Also do sign extension in BITS_PER_WORD == 16 case.

	* emit-rtl.c (constant_subword): Also do sign extension in
	BITS_PER_WORD == 16 case.

From-SVN: r41545

gcc/ChangeLog

+Wed Apr 25 17:09:50 2001  J"orn Rennecke <amylaar@redhat.com>
+
+	* emit-rtl.c (constant_subword): Also do sign extension in
+	BITS_PER_WORD == 16 case.
+
 2001-04-25  Jason Merrill  <jason_merrill@redhat.com>
 
 	* loop.c (try_swap_copy_prop): Go back to checking insn.

gcc/emit-rtl.c

@@ -1369,7 +1369,7 @@ constant_subword (op, offset, mode)
 	  val = k[offset >> 1];
 	  if ((offset & 1) == ! WORDS_BIG_ENDIAN)
 	    val >>= 16;
-	  val &= 0xffff;
+	  val = ((val & 0xffff) ^ 0x8000) - 0x8000;
 	  return GEN_INT (val);
 	}
       else
@@ -1448,7 +1448,7 @@ constant_subword (op, offset, mode)
 	{
 	  if ((offset & 1) == ! WORDS_BIG_ENDIAN)
 	    val >>= 16;
-	  val &= 0xffff;
+	  val = ((val & 0xffff) ^ 0x8000) - 0x8000;
 	}
 
       return GEN_INT (val);