On Dec 7, 2010, at 10:30 AM, Paulo J. Matos wrote:
> Paul Koning <paul_kon...@dell.com> writes:
>
>>> I assume you by 'instruction' here mean a define_insn and not a single
>>> RTL or assembler instruction.
>>>
>>> So, assume I have two classes M_REGS and Y_REGS and I cannot move
>>> between them except if I go through an intermediary in C_REGS.
>>> Do I need a secondary reload?
>>
>> Yes
>>>
>>> I wouldn't expect so cause I could write a rule that has a scratch from
>>> C_REGS. Then I move the value from SOURCE to C_REGS and from C_REGS to
>>> DEST. Have I misunderstood what you said?
>>>
>
> What about the above case?
> Couldn't you have something like I described above:
> (define_insn "transfer"
> [
> (set (match_operand 0 "register_operand" "m")
> (match_operand 1 "register_operand" "y"))
> (clobber (match_scratch 2 "c"))
> ]
> ""
> {
> move from 1 to 2;
> move from 2 to 0;
> })
>
> Why would something like this not work and force you to have a secondary
> reload hook?
I don't know enough to answer that. But I do know that the secondary reload
stuff works great, and is reasonably well documented, and it takes only a few
lines to put into effect. Why not give it a try?
paul
