https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120059
--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This semi obvious patch fixes it. The only thing I am not 100% sure yet is why
is simplify_gen_subreg failing; but yes simplify_gen_subreg is known in some
cases to return NULL.
```
diff --git a/gcc/simplify-rtx.cc b/gcc/simplify-rtx.cc
index 7c4d8e6cfdb..7bcbe11370f 100644
--- a/gcc/simplify-rtx.cc
+++ b/gcc/simplify-rtx.cc
@@ -3063,6 +3063,10 @@ simplify_with_subreg_not (rtx_code binop, machine_mode
mode, rtx op0, rtx op1)
XEXP (SUBREG_REG (opn), 0),
GET_MODE (SUBREG_REG (opn)),
SUBREG_BYTE (opn));
+
+ if (!new_subreg)
+ return NULL_RTX;
+
rtx new_not = simplify_gen_unary (NOT, mode, new_subreg, mode);
if (opn == op0)
return simplify_gen_binary (binop, mode, new_not, op1);
```
