[Bug target/65657] [avr] read from __memx address space tramples argument to following function

["senthil_kumar.selvaraj at atmel dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65657

--- Comment #4 from Senthil Kumar Selvaraj <senthil_kumar.selvaraj at atmel dot com> ---
Doesn't appear to be a missed clobber in the md file, as *.expand shows in insn
7 - r22 is in the clobbered registers list. Later passes assume r22 is unused
after insn 6 (reg:R22 QI is marked as REG_UNUSED), and proceed to set r22
instead of r24 in insn 7.

(note 4 1 2 2 [bb 2] NOTE_INSN_BASIC_BLOCK)
(insn 2 4 3 2 (set (reg/v/f:PSI 43 [ x ])
        (reg:PSI 22 r22 [ x ])) foo.c:3 -1
     (nil))
(note 3 2 6 2 NOTE_INSN_FUNCTION_BEG)
(insn 6 3 7 2 (set (reg:HI 22 r22)
        (const_int -21555 [0xffffffffffffabcd])) foo.c:4 -1
     (nil))
(insn 7 6 8 2 (parallel [
            (set (reg:QI 24 r24)
                (mem:QI (reg/v/f:PSI 43 [ x ]) [0 *x_2(D)+0 S1 A8 AS7]))
            (clobber (reg:QI 22 r22))
            (clobber (reg:QI 21 r21))
            (clobber (reg:HI 30 r30))
        ]) foo.c:4 -1
     (nil))
(call_insn/j 8 7 9 2 (parallel [
            (call (mem:HI (symbol_ref:HI ("foo") [flags 0x41]  <function_decl
0x7f635059f360 foo>) [0 foo S2 A8])
                (const_int 0 [0]))
            (use (const_int 1 [0x1]))
        ]) foo.c:4 -1
     (expr_list:REG_CALL_DECL (symbol_ref:HI ("foo") [flags 0x41] 
<function_decl 0x7f635059f360 foo>)
        (nil))
    (expr_list:QI (use (reg:QI 24 r24))
        (expr_list:HI (use (reg:HI 22 r22))
            (nil))))
(barrier 9 8 0)