llvm dev - Dec 2015 - Reserve registers not to be used by the compiler

Does anyone know if there is a way to reserve a register set not to be used
by a compiler? For example there are 64 available registers and the
compiler can use only registers 0-31 and 40-45, and the others should be
left alone.

I know that the simplest solution is to simply change number registers in
one of the .td files, but what I'm looking is an option to use at run time.
I need this to research various register combinations. Recompiling and
running tests takes some time. If I could compile my code with say 128
registers and thn tell compiler to use only a certain set (say 0-32) at run
time then this would significantly speed up my testing. I would be able to
see what the code is doing for the same test with a 32 registers vs 64 vs
96 vs any number up to 128.

Does anyone know if there is a way to do it? Any help is appreciated.

-- 
Rail Shafigulin
Software Engineer
Esencia Technologies
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20151221/e5011641/attachment.html>

On 12/21/2015 07:40 PM, Rail Shafigulin via llvm-dev
wrote:
> Does anyone know if there is a way to reserve a register set not to be 
> used by a compiler? For example there are 64 available registers and 
> the compiler can use only registers 0-31 and 40-45, and the others 
> should be left alone.
>
> I know that the simplest solution is to simply change number registers 
> in one of the .td files, but what I'm looking is an option to use at 
> run time. I need this to research various register combinations. 
> Recompiling and running tests takes some time. If I could compile my 
> code with say 128 registers and thn tell compiler to use only a 
> certain set (say 0-32) at run time then this would significantly speed 
> up my testing. I would be able to see what the code is doing for the 
> same test with a 32 registers vs 64 vs 96 vs any number up to 128.
>
> Does anyone know if there is a way to do it? Any help is appreciated.
>
> -- 
> Rail Shafigulin
> Software Engineer
> Esencia Technologies
>
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
You can override TargetRegisterInfo::getReservedRegs and reserve any 
registers you do not want allocated.

-Matt
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20151221/09627b15/attachment.html>

>
> You can override TargetRegisterInfo::getReservedRegs and reserve any
> registers you do not want allocated.
>
> -Matt
>
Thanks.

-- 
Rail Shafigulin
Software Engineer
Esencia Technologies
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20151223/f34833cd/attachment.html>