llvm dev - Jun 2015 - [LLVMdev] non-standard machine value types

Hi all.

I'm looking for a ways of defining register files with non-standard machine
value type in tablegen. The value types not covered by SimpleValueType
enum. For example (from the top of my head) 25 bit integers, or 8 way 18
bit integers. These types going to be used with intrinsics so I also need
appropriate C custom types defined.

I wonder if I can describe those in tablegen files or do I need to extend
llvm. What is the right way of supporting such types?

I'm not familiar will llvm internals so far, so any help and pointers
appreciated.

Thanks,
Volodymyr.
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> On Jun 3, 2015, at 11:48 PM, Volodymyr Arbatov <gm.ivlad at
gmail.com> wrote:
> 
> Hi all.
> 
> I'm looking for a ways of defining register files with non-standard
machine value type in tablegen. The value types not covered by SimpleValueType
enum. For example (from the top of my head) 25 bit integers, or 8 way 18 bit
integers. These types going to be used with intrinsics so I also need
appropriate C custom types defined.
> 
> I wonder if I can describe those in tablegen files or do I need to extend
llvm. What is the right way of supporting such types?
> 
> I'm not familiar will llvm internals so far, so any help and pointers
appreciated.
> 
> Thanks,
> Volodymyr.
> ___________________
You would need an MVT type defined for every legal type you have, so you would
need to add those. However, LLVM has a pretty widely spread assumption of 8-bit
bytes, so that will be far more problematic for your target. Fixing that would
be a large project.

-Matt
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We maintain a set of patches for enabling 24/40-bit MVTs, and also a set of
patches to support 16-bit bytes. I can provide them upon request. (Only llvm, no
clang patches yet.)

/Patrik Hägglund

From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On
Behalf Of Matt Arsenault
Sent: den 4 juni 2015 09:07
To: Volodymyr Arbatov
Cc: llvmdev at cs.uiuc.edu
Subject: Re: [LLVMdev] non-standard machine value types


On Jun 3, 2015, at 11:48 PM, Volodymyr Arbatov <gm.ivlad at
gmail.com<mailto:gm.ivlad at gmail.com>> wrote:

Hi all.

I'm looking for a ways of defining register files with non-standard machine
value type in tablegen. The value types not covered by SimpleValueType enum. For
example (from the top of my head) 25 bit integers, or 8 way 18 bit integers.
These types going to be used with intrinsics so I also need appropriate C custom
types defined.

I wonder if I can describe those in tablegen files or do I need to extend llvm.
What is the right way of supporting such types?

I'm not familiar will llvm internals so far, so any help and pointers
appreciated.

Thanks,
Volodymyr.
___________________

You would need an MVT type defined for every legal type you have, so you would
need to add those. However, LLVM has a pretty widely spread assumption of 8-bit
bytes, so that will be far more problematic for your target. Fixing that would
be a large project.

-Matt
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