From a552a808f004c90d6f880f296041d674bdc27eda Mon Sep 17 00:00:00 2001
From: Tejas Belagod <tejas.belagod@arm.com>
Date: Mon, 2 Sep 2024 20:53:42 +0530
Subject: [PATCH] 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.
---
 gcc/rtlanal.cc | 1 +
 1 file changed, 1 insertion(+)

diff --git a/gcc/rtlanal.cc b/gcc/rtlanal.cc
index cb0c0c0d719..b58401e8309 100644
--- 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);
     }