rtl: Validate subreg info when optimizing vec_select.

When optimizing for NOPs in case of overlapping regs in VEC_SELECT expressions,
validate subreg data before using simplify_subreg_regno.  There is no real
SUBREG rtx here, but a pseudo subreg call to check if subregs are possible.

gcc/ChangeLog:

	* rtlanal.cc (set_noop_p): Validate subreg constraints before checking
	for overlapping regs using simplify_subreg_regno.

diff --git a/gcc/rtlanal.cc b/gcc/rtlanal.cc
index cb0c0c0d71977ff833083ce3eee192990ef3f7ef..b58401e8309fb99cc572a7982831fcf16f51191a 100644 (file)
--- a/gcc/rtlanal.cc
+++ b/gcc/rtlanal.cc
@@ -1686,6 +1686,7 @@ set_noop_p (const_rtx set)
        }
       return
        REG_CAN_CHANGE_MODE_P (REGNO (dst), GET_MODE (src0), GET_MODE (dst))
+       && validate_subreg (GET_MODE (dst), GET_MODE (src0), src0, offset)
        && simplify_subreg_regno (REGNO (src0), GET_MODE (src0),
                                  offset, GET_MODE (dst)) == (int) REGNO (dst);
     }