avr-g++ (head) does not compile anymore

[Klaus Doldinger]

Trying to compile head for avr-target yields the following error:

../../../../libgcc/libgcc2.c: In function '__negvhi2':
../../../../libgcc/libgcc2.c:187:1: error: insn does not satisfy its
constraints:
  187 | }
      | ^
(jump_insn 75 32 54 5 (set (pc)
        (if_then_else (eq (zero_extract:HI (reg:QI 25 r25 [ <retval>+1 ])
                    (const_int 1 [0x1])
                    (const_int 7 [0x7]))
                (const_int 0 [0]))
            (label_ref 47)
            (pc))) "../../../../libgcc/libgcc2.c":183:6 154 {*addsi3.lt0}
     (nil)
 -> 47)
during RTL pass: cprop_hardreg
../../../../libgcc/libgcc2.c:187:1: internal compiler error: in
extract_constrain_insn, at recog.c:2206
0x5fd447 _fatal_insn(char const*, rtx_def const*, char const*, int, char
const*)
        ../../gcc/rtl-error.c:108
0x5fd47f _fatal_insn_not_found(rtx_def const*, char const*, int, char
const*)
        ../../gcc/rtl-error.c:118
0x5fbac3 extract_constrain_insn(rtx_insn*)
        ../../gcc/recog.c:2206
0xc01b40 copyprop_hardreg_forward_1
        ../../gcc/regcprop.c:801
0xc028cc execute
        ../../gcc/regcprop.c:1307


Any hints on this?