Re: Delay slot problem

[Ian Lance Taylor <iant at google dot com>]

Camo Johnson <da_cramp@yahoo.de> writes:

> I have some trouble dealing with delay slots. The problem is that our 
> architecture can't handle branch instructions using registers which have been 
> changed in the previous instruction. So a delay slot is needed.
> The difficult part is, that this delay slot is only needed if the same register 
> is used in the branch instruction. I have no idea how I should describe this 
> using the instruction attributes which are usually used for delay slots. Is it 
> somehow possible to extract the register number and store it in a const_int 
> attribute?

That is not really what gcc calls a delay slot.  I don't think the
existing delay slot mechanisms are going to help you.  This is something
which you can try to avoid using the instruction scheduler, and you will
probably have to insert some required nops in the machine_reorg pass
(see mips_reorg in config/mips/mips.c for an example of that).

Ian