define_split question

[Ian Lance Taylor]

Lars Poeschel <larsi@wh2.tu-dresden.de> writes:

> I have the following statement, which fails with general compiler errror in 
> gen_rtx_SUBREG, at emit-rtl.c:729
> 
> (define_split
>   [(set (match_operand:DI 0 "memory_operand" "=m")
>         (match_operand:DI 1 "register_operand" "r"))]
>   ""
>   [(set (mem:SI (match_dup 0) )
>         (subreg:SI (match_dup 1) 0))
>   (set (mem:SI (plus:SI (match_dup 0) (const_int 4)))
>        (subreg:SI (match_dup 1) 1))]
>   "")
> 
> What I want to do is implementing the movdi on a 32 bit platform. This split 
> is a special case for memory destination and register source. I want to split 
> the 64 bit move into 2 32 bit moves. What am I doing wrong ? Anyone an idea ?

In general, with some exceptions, you shouldn't use an explicit subreg
in an insn pattern.  You should instead just use (match_dup N), and in
your C code use operands[N] = simplify_gen_subreg (...).

Otherwise you can wind up with a subreg of a subreg which is
forbidden.

Ian