Re: [PATCH 2/3] MIPS: Add full ISA emulator.

[David Daney <ddaney@caviumnetworks.com>]

On 12/04/2014 03:49 AM, Maciej W. Rozycki wrote:
> On Wed, 3 Dec 2014, David Daney wrote:
>
>>> but it doesn't support customized instructions,
>>
>> GCC will never put these in the delay slot of a FPU branch, so it is not
>> needed.
>>
>>> multiple ASEs,
>>
>> Same as above.  But any instructions that are deemed necessary can easily be
>> added.
>
>   GAS will happily schedule any instruction into a branch delay slot as
> long as the instruction is not architecturally forbidden there (e.g.
> ERET), there is no data dependency with the branch that would affect the
> result produced and the instruction is not an explicit exception trap
> operation (BREAK, SYSCALL, TEQ, etc.).  For some reason, unknown to me all
> MT ASE instructions are disallowed too.  Anything else -- free to go in!
>
>   Of course instructions can be scheduled into branch delay slots manually
> too, in handcoded assembly, and that has to continue working.
>

It is not difficult to also emulate the trapping instructions.  In order 
to move forward, I will implement the trapping instructions in my 
emulator for the next patch.

Thanks,
David Daney