llvm dev - Dec 2009 - [LLVMdev] [PATCH] increase the max number of physical registers

Hello,

Attached is a trivial patch to increase the max number of physical
registers in LLVM from 1024 to 16384.

In our TCE toolset we allow the designer to choose the number of 
registers in the designed TTA processors freely, and recently
while experimenting with using TTA for a GPU design we have
bumped into this limit several times.

What has made matters a bit worse for us is that we need to
reserve two reg indices for each register so they can be used
both for integer and floating point computation, thus the
current limit is 512 registers and the patch lifts it to 8K
which should be enough for a while.

The patch applies cleanly to LLVM 2.5, 2.6 and trunk.
'make check' passes in trunk with this patch.

Best regards,
-- 
Pekka Jääskeläinen
http://tce.cs.tut.fi
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Hello, Pekka
>Attached is a trivial patch to increase the max number of physical
>registers in LLVM from 1024 to 16384.
Just random thought - could this be a configure-time option?

-- 
With best regards, Anton Korobeynikov
Faculty of Mathematics and Mechanics, Saint Petersburg State University

Anton Korobeynikov wrote:
>> Attached is a trivial patch to increase the max number of physical
>> registers in LLVM from 1024 to 16384.
> Just random thought - could this be a configure-time option?
I'd say that if there is no strong reason (I have no clue if
there is) to keep the number lower, I think the configure option
just adds clutter to the configure script.

-- 
Pekka Jääskeläinen
Department of Computer Systems
Tampere University of Technology, Finland
http://tce.cs.tut.fi

On Nov 21, 2009, at 1:15 PM, Pekka Jääskeläinen wrote:
> Hello,
> 
> Attached is a trivial patch to increase the max number of physical
> registers in LLVM from 1024 to 16384.
> 
> In our TCE toolset we allow the designer to choose the number of registers
in the designed TTA processors freely, and recently
> while experimenting with using TTA for a GPU design we have
> bumped into this limit several times.
> 
> What has made matters a bit worse for us is that we need to
> reserve two reg indices for each register so they can be used
> both for integer and floating point computation, thus the
> current limit is 512 registers and the patch lifts it to 8K
> which should be enough for a while.
> 
> The patch applies cleanly to LLVM 2.5, 2.6 and trunk.
> 'make check' passes in trunk with this patch.
This is fine to me in principle, but please make sure this doesn't impact
compile time or memory usage of llc somehow.

-Chris

Hi,

Chris Lattner wrote:
> This is fine to me in principle, but please make sure this doesn't
> impact compile time or memory usage of llc somehow.
OK. Any recommended way to do this? Is there some nice way to benchmark
speed + memory consumption of llc in LLVM testing infra at the
moment or should I just use 'top' to the inspect memory consumption
and 'time' for speed measurements with a code generation from
a big bitcode?

-- 
Pekka Jääskeläinen
Department of Computer Systems
Tampere University of Technology, Finland
http://tce.cs.tut.fi

Hello,

Can someone please commit this patch?

Thanks.

On 11/21/2009 11:15 PM, Pekka Jääskeläinen wrote:
> Hello,
> 
> Attached is a trivial patch to increase the max number of physical
> registers in LLVM from 1024 to 16384.
> 
> In our TCE toolset we allow the designer to choose the number of 
> registers in the designed TTA processors freely, and recently
> while experimenting with using TTA for a GPU design we have
> bumped into this limit several times.
> 
> What has made matters a bit worse for us is that we need to
> reserve two reg indices for each register so they can be used
> both for integer and floating point computation, thus the
> current limit is 512 registers and the patch lifts it to 8K
> which should be enough for a while.
> 
> The patch applies cleanly to LLVM 2.5, 2.6 and trunk.
> 'make check' passes in trunk with this patch.
> 
> Best regards,
> 

-- 
Pekka

Here's the actual patch, sorry ;)

On 12/07/2009 09:02 PM, Pekka Jääskeläinen wrote:
> Hello,
> 
> Can someone please commit this patch?
> 
> Thanks.
> 
> On 11/21/2009 11:15 PM, Pekka Jääskeläinen wrote:
>> Hello,
>>
>> Attached is a trivial patch to increase the max number of physical
>> registers in LLVM from 1024 to 16384.
>>
>> In our TCE toolset we allow the designer to choose the number of 
>> registers in the designed TTA processors freely, and recently
>> while experimenting with using TTA for a GPU design we have
>> bumped into this limit several times.
>>
>> What has made matters a bit worse for us is that we need to
>> reserve two reg indices for each register so they can be used
>> both for integer and floating point computation, thus the
>> current limit is 512 registers and the patch lifts it to 8K
>> which should be enough for a while.
>>
>> The patch applies cleanly to LLVM 2.5, 2.6 and trunk.
>> 'make check' passes in trunk with this patch.
>>
>> Best regards,
>>
> 
> 

-- 
Pekka
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