https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102254
--- Comment #7 from Hongtao.liu <crazylht at gmail dot com> ---
And here is invalid subreg from general_operand
#ifdef INSN_SCHEDULING
/* On machines that have insn scheduling, we want all memory
reference to be explicit, so outlaw paradoxical SUBREGs.
However, we must allow them after reload so that they can
get cleaned up by cleanup_subreg_operands. */
if (!reload_completed && MEM_P (sub)
&& paradoxical_subreg_p (op))
return false;
#endif
/* Avoid memories with nonzero SUBREG_BYTE, as offsetting the memory
may result in incorrect reference. We should simplify all valid
subregs of MEM anyway. But allow this after reload because we
might be called from cleanup_subreg_operands.
??? This is a kludge. */
if (!reload_completed
&& maybe_ne (SUBREG_BYTE (op), 0)
&& MEM_P (sub))
return false;
if (REG_P (sub)
&& REGNO (sub) < FIRST_PSEUDO_REGISTER
&& !REG_CAN_CHANGE_MODE_P (REGNO (sub), GET_MODE (sub), mode)
&& GET_MODE_CLASS (GET_MODE (sub)) != MODE_COMPLEX_INT
&& GET_MODE_CLASS (GET_MODE (sub)) != MODE_COMPLEX_FLOAT
/* LRA can generate some invalid SUBREGS just for matched
operand reload presentation. LRA needs to treat them as
valid. */
&& ! LRA_SUBREG_P (op))
return false;
/* FLOAT_MODE subregs can't be paradoxical. Combine will occasionally
create such rtl, and we must reject it. */
if (SCALAR_FLOAT_MODE_P (GET_MODE (op))
/* LRA can use subreg to store a floating point value in an
integer mode. Although the floating point and the
integer modes need the same number of hard registers, the
size of floating point mode can be less than the integer
mode. */
&& ! lra_in_progress
&& paradoxical_subreg_p (op))
return false;
