llvm dev - May 2012 - [LLVMdev] RFC: R600, a new backend for AMD GPUs

Hi Tom,

I have a higher-level question regarding this back-end.  If I have an LLVM
IR module and run it through this back-end, it seems like the only output
option is a binary format.  Is this a device binary, or another
intermediate format?

If the input LLVM IR module was a compute kernel, how would I go about
executing it on an AMD GPU?  Can I use the APP SDK to load the binary,
perhaps through the CAL interfaces?  How about the OpenCL binary interface?

On Tue, Apr 24, 2012 at 2:52 PM, Tom Stellard <tstellar at gmail.com>
wrote:
> On Mon, Mar 26, 2012 at 12:50:07PM -0400, Tom Stellard wrote:
> > Hi,
> >
> > We've been working on an LLVM backend for the previous generation
of AMD
> > GPUs (HD 2XXX - HD 6XXX) and we would like submit it for inclusion in
the
> > main LLVM tree.  The latest code can be found in this git repository:
> > http://cgit.freedesktop.org/~tstellar/llvm/ in the r600-initial-review
> > branch or if you prefer you can download the entire tree with this
link:
> >
>
http://cgit.freedesktop.org/~tstellar/llvm/snapshot/llvm-r600-initial-review.tar.gz
> > The R600 backend is located in lib/Target/AMDIL
> >
> > First, a brief description of the backend:
> >
> > The r600 backend is being developed as a part of the Open Source
compute
> > stack in Mesa (http://www.mesa3d.org/), which uses the Gallium API.
> > It uses large portions of the AMDIL backend which was open-sourced
> > last December and you'll notice the TargetMachine for this backend
> > (AMDGPUTargetMachine) is a sub-class of AMDILTargetMachine.  We are
also
> > currently working on an LLVM backend for Southern Islands GPUs, and we
> > would like to get that code into the LLVM tree as well, once it has
been
> > approved for release.  The Southern Islands backend will be used for
> > compute shaders and also graphics shaders in the AMD open source 3D
> driver.
> >
> > One thing that I would like to point out is that all of the
> > code from the AMDIL backend is licensed under a BSD license with an
> > additional clause that deals with United States export laws (non-AMDIL
> > code is licensed with the University of Illinois Open Source License).
> > Will the LLVM project accept a backend with code licensed under this
BSD
> > license?  We would prefer to keep this license, but if it isn't
> > acceptable, we can try to relicense it.
> >
> > Second, I am looking for two categories of feedback for the r600
backend:
> >
> > 1. What changes do I need to make to get the backend included in the
> LLVM tree.
> > 2. What changes can I make to improve the backend overall.
> >
> > My top priority is to get the backend into the LLVM tree, so
> > when you provide feedback if you could be clear about what
> > changes are needed to get the backend into the tree versus what
changes
> > are just general improvements, I would appreciate it.
> >
> > Lastly, I did a very brief run through of the code to check the coding
> style,
> > but I know there are still some violations.  For example, a lot of the
> > file headers are missing file descriptions.  I didn't want to
spend a
> > lot of time on coding style changes prior to the initial review in
case
> > I was asked to make big changes to the code, so I will address these
> > issues once I have received an OK on the organization of the code.
> > However, please still point out coding style errors to me, and
I'll be
> > sure to fix them during the final pass.
> >
> > Looking forward to your feedback.
> >
>
> Hi,
>
> Based on some feedback I received on IRC today, it sounds like this
> is just too much code to review at once.  I'm going to try to strip
> the R600 backend down to the bare minimum that is needed for our Mesa
> drivers and then repost the code to the list.  Hopefully, this will make it
> easier for people to review.
>
> -Tom
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>


-- 

Thanks,

Justin Holewinski
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On Fri, May 25, 2012 at 02:37:26PM -0700, Justin Holewinski
wrote:
> Hi Tom,
> 
> I have a higher-level question regarding this back-end.  If I have an LLVM
> IR module and run it through this back-end, it seems like the only output
> option is a binary format.  Is this a device binary, or another
> intermediate format?
> 
> If the input LLVM IR module was a compute kernel, how would I go about
> executing it on an AMD GPU?  Can I use the APP SDK to load the binary,
> perhaps through the CAL interfaces?  How about the OpenCL binary interface?
>
Hi Justin,

The binary produced by this backend is meant to be consumed by AMD's Open
Source 3D/Compute drivers which are part of the Mesa3D[1] project.  The
backend is integrated into the driver, so you don't need to compile
shaders offline.  Currently we are using the backend for graphics and
compute shaders in our r600g driver (HD2xxx-HD6xxx GPUs) and for graphics
in our radeonsi (HD7xxx GPUs).  In the future we will use it for compute
shaders on radensi too.

In order to use the backend for graphics on r600g, you need to build
Mesa with the --enable-r600-llvm-compiler option.  For compute the
installation instructions are here:
http://dri.freedesktop.org/wiki/GalliumCompute

We're working hard to get everything upstream into LLVM to so we can
have compute shaders working out of the box, so our users don't need to
manually apply patches.

Let me know if you have any other questions.

-Tom

[1] http://www.mesa3d.org/
> On Tue, Apr 24, 2012 at 2:52 PM, Tom Stellard <tstellar at gmail.com>
wrote:
> 
> > On Mon, Mar 26, 2012 at 12:50:07PM -0400, Tom Stellard wrote:
> > > Hi,
> > >
> > > We've been working on an LLVM backend for the previous
generation of AMD
> > > GPUs (HD 2XXX - HD 6XXX) and we would like submit it for
inclusion in the
> > > main LLVM tree.  The latest code can be found in this git
repository:
> > > http://cgit.freedesktop.org/~tstellar/llvm/ in the
r600-initial-review
> > > branch or if you prefer you can download the entire tree with
this link:
> > >
> >
http://cgit.freedesktop.org/~tstellar/llvm/snapshot/llvm-r600-initial-review.tar.gz
> > > The R600 backend is located in lib/Target/AMDIL
> > >
> > > First, a brief description of the backend:
> > >
> > > The r600 backend is being developed as a part of the Open Source
compute
> > > stack in Mesa (http://www.mesa3d.org/), which uses the Gallium
API.
> > > It uses large portions of the AMDIL backend which was
open-sourced
> > > last December and you'll notice the TargetMachine for this
backend
> > > (AMDGPUTargetMachine) is a sub-class of AMDILTargetMachine.  We
are also
> > > currently working on an LLVM backend for Southern Islands GPUs,
and we
> > > would like to get that code into the LLVM tree as well, once it
has been
> > > approved for release.  The Southern Islands backend will be used
for
> > > compute shaders and also graphics shaders in the AMD open source
3D
> > driver.
> > >
> > > One thing that I would like to point out is that all of the
> > > code from the AMDIL backend is licensed under a BSD license with
an
> > > additional clause that deals with United States export laws
(non-AMDIL
> > > code is licensed with the University of Illinois Open Source
License).
> > > Will the LLVM project accept a backend with code licensed under
this BSD
> > > license?  We would prefer to keep this license, but if it
isn't
> > > acceptable, we can try to relicense it.
> > >
> > > Second, I am looking for two categories of feedback for the r600
backend:
> > >
> > > 1. What changes do I need to make to get the backend included in
the
> > LLVM tree.
> > > 2. What changes can I make to improve the backend overall.
> > >
> > > My top priority is to get the backend into the LLVM tree, so
> > > when you provide feedback if you could be clear about what
> > > changes are needed to get the backend into the tree versus what
changes
> > > are just general improvements, I would appreciate it.
> > >
> > > Lastly, I did a very brief run through of the code to check the
coding
> > style,
> > > but I know there are still some violations.  For example, a lot
of the
> > > file headers are missing file descriptions.  I didn't want to
spend a
> > > lot of time on coding style changes prior to the initial review
in case
> > > I was asked to make big changes to the code, so I will address
these
> > > issues once I have received an OK on the organization of the
code.
> > > However, please still point out coding style errors to me, and
I'll be
> > > sure to fix them during the final pass.
> > >
> > > Looking forward to your feedback.
> > >
> >
> > Hi,
> >
> > Based on some feedback I received on IRC today, it sounds like this
> > is just too much code to review at once.  I'm going to try to
strip
> > the R600 backend down to the bare minimum that is needed for our Mesa
> > drivers and then repost the code to the list.  Hopefully, this will
make it
> > easier for people to review.
> >
> > -Tom
> > _______________________________________________
> > LLVM Developers mailing list
> > LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
> >
> 
> 
> 
> -- 
> 
> Thanks,
> 
> Justin Holewinski

On May 28, 2012 6:44 AM, "Tom Stellard" <thomas.stellard at
amd.com> wrote:
>
> On Fri, May 25, 2012 at 02:37:26PM -0700, Justin Holewinski wrote:
> > Hi Tom,
> >
> > I have a higher-level question regarding this back-end.  If I have an
LLVM
> > IR module and run it through this back-end, it seems like the only
output
> > option is a binary format.  Is this a device binary, or another
> > intermediate format?
> >
> > If the input LLVM IR module was a compute kernel, how would I go about
> > executing it on an AMD GPU?  Can I use the APP SDK to load the binary,
> > perhaps through the CAL interfaces?  How about the OpenCL binary
interface?
> >
>
> Hi Justin,
>
> The binary produced by this backend is meant to be consumed by AMD's
Open
> Source 3D/Compute drivers which are part of the Mesa3D[1] project.  The
> backend is integrated into the driver, so you don't need to compile
> shaders offline.  Currently we are using the backend for graphics and
> compute shaders in our r600g driver (HD2xxx-HD6xxx GPUs) and for graphics
> in our radeonsi (HD7xxx GPUs).  In the future we will use it for compute
> shaders on radensi too.
>
> In order to use the backend for graphics on r600g, you need to build
> Mesa with the --enable-r600-llvm-compiler option.  For compute the
> installation instructions are here:
> http://dri.freedesktop.org/wiki/GalliumCompute
>
> We're working hard to get everything upstream into LLVM to so we can
> have compute shaders working out of the box, so our users don't need to
> manually apply patches.
Okay, so there is no way to use the backend to produce loadable compute
kernels for the proprietary drivers, or on Mac/windows?
>
> Let me know if you have any other questions.
>
> -Tom
>
> [1] http://www.mesa3d.org/
>
> > On Tue, Apr 24, 2012 at 2:52 PM, Tom Stellard <tstellar at
gmail.com>
wrote:
> >
> > > On Mon, Mar 26, 2012 at 12:50:07PM -0400, Tom Stellard wrote:
> > > > Hi,
> > > >
> > > > We've been working on an LLVM backend for the previous
generation
of AMD
> > > > GPUs (HD 2XXX - HD 6XXX) and we would like submit it for
inclusion
in the
> > > > main LLVM tree.  The latest code can be found in this git
repository:
> > > > http://cgit.freedesktop.org/~tstellar/llvm/ in the
r600-initial-review
> > > > branch or if you prefer you can download the entire tree
with this
link:
> > > >
> > >
http://cgit.freedesktop.org/~tstellar/llvm/snapshot/llvm-r600-initial-review.tar.gz
> > > > The R600 backend is located in lib/Target/AMDIL
> > > >
> > > > First, a brief description of the backend:
> > > >
> > > > The r600 backend is being developed as a part of the Open
Source
compute
> > > > stack in Mesa (http://www.mesa3d.org/), which uses the
Gallium API.
> > > > It uses large portions of the AMDIL backend which was
open-sourced
> > > > last December and you'll notice the TargetMachine for
this backend
> > > > (AMDGPUTargetMachine) is a sub-class of AMDILTargetMachine. 
We are
also
> > > > currently working on an LLVM backend for Southern Islands
GPUs, and
we
> > > > would like to get that code into the LLVM tree as well, once
it has
been
> > > > approved for release.  The Southern Islands backend will be
used for
> > > > compute shaders and also graphics shaders in the AMD open
source 3D
> > > driver.
> > > >
> > > > One thing that I would like to point out is that all of the
> > > > code from the AMDIL backend is licensed under a BSD license
with an
> > > > additional clause that deals with United States export laws
(non-AMDIL
> > > > code is licensed with the University of Illinois Open Source
License).
> > > > Will the LLVM project accept a backend with code licensed
under
this BSD
> > > > license?  We would prefer to keep this license, but if it
isn't
> > > > acceptable, we can try to relicense it.
> > > >
> > > > Second, I am looking for two categories of feedback for the
r600
backend:
> > > >
> > > > 1. What changes do I need to make to get the backend
included in the
> > > LLVM tree.
> > > > 2. What changes can I make to improve the backend overall.
> > > >
> > > > My top priority is to get the backend into the LLVM tree, so
> > > > when you provide feedback if you could be clear about what
> > > > changes are needed to get the backend into the tree versus
what
changes
> > > > are just general improvements, I would appreciate it.
> > > >
> > > > Lastly, I did a very brief run through of the code to check
the
coding
> > > style,
> > > > but I know there are still some violations.  For example, a
lot of
the
> > > > file headers are missing file descriptions.  I didn't
want to spend
a
> > > > lot of time on coding style changes prior to the initial
review in
case
> > > > I was asked to make big changes to the code, so I will
address these
> > > > issues once I have received an OK on the organization of the
code.
> > > > However, please still point out coding style errors to me,
and I'll
be
> > > > sure to fix them during the final pass.
> > > >
> > > > Looking forward to your feedback.
> > > >
> > >
> > > Hi,
> > >
> > > Based on some feedback I received on IRC today, it sounds like
this
> > > is just too much code to review at once.  I'm going to try to
strip
> > > the R600 backend down to the bare minimum that is needed for our
Mesa
> > > drivers and then repost the code to the list.  Hopefully, this
will
make it
> > > easier for people to review.
> > >
> > > -Tom
> > > _______________________________________________
> > > LLVM Developers mailing list
> > > LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> > > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
> > >
> >
> >
> >
> > --
> >
> > Thanks,
> >
> > Justin Holewinski
>
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Justin,
This backend is for the Open Source linux driver, not the AMD Catalyst OpenCL
driver. The backend for AMDIL that I open sourced in December can be used on the
APP SDK with some modifications via calclCompile and can be loaded with a tool
that creates ELF files via clCompileProgramFromBinary in OpenCL.
We are working on making this process more useful, but right now it requires
outside tools to work.

Micah


From: Justin Holewinski [mailto:justin.holewinski at gmail.com]
Sent: Friday, May 25, 2012 2:37 PM
To: Tom Stellard
Cc: Stellard, Thomas; Villmow, Micah; llvmdev at cs.uiuc.edu
Subject: Re: [LLVMdev] RFC: R600, a new backend for AMD GPUs

Hi Tom,

I have a higher-level question regarding this back-end.  If I have an LLVM IR
module and run it through this back-end, it seems like the only output option is
a binary format.  Is this a device binary, or another intermediate format?

If the input LLVM IR module was a compute kernel, how would I go about executing
it on an AMD GPU?  Can I use the APP SDK to load the binary, perhaps through the
CAL interfaces?  How about the OpenCL binary interface?
On Tue, Apr 24, 2012 at 2:52 PM, Tom Stellard <tstellar at
gmail.com<mailto:tstellar at gmail.com>> wrote:
On Mon, Mar 26, 2012 at 12:50:07PM -0400, Tom Stellard
wrote:
> Hi,
>
> We've been working on an LLVM backend for the previous generation of
AMD
> GPUs (HD 2XXX - HD 6XXX) and we would like submit it for inclusion in the
> main LLVM tree.  The latest code can be found in this git repository:
> http://cgit.freedesktop.org/~tstellar/llvm/ in the r600-initial-review
> branch or if you prefer you can download the entire tree with this link:
>
http://cgit.freedesktop.org/~tstellar/llvm/snapshot/llvm-r600-initial-review.tar.gz
> The R600 backend is located in lib/Target/AMDIL
>
> First, a brief description of the backend:
>
> The r600 backend is being developed as a part of the Open Source compute
> stack in Mesa (http://www.mesa3d.org/), which uses the Gallium API.
> It uses large portions of the AMDIL backend which was open-sourced
> last December and you'll notice the TargetMachine for this backend
> (AMDGPUTargetMachine) is a sub-class of AMDILTargetMachine.  We are also
> currently working on an LLVM backend for Southern Islands GPUs, and we
> would like to get that code into the LLVM tree as well, once it has been
> approved for release.  The Southern Islands backend will be used for
> compute shaders and also graphics shaders in the AMD open source 3D driver.
>
> One thing that I would like to point out is that all of the
> code from the AMDIL backend is licensed under a BSD license with an
> additional clause that deals with United States export laws (non-AMDIL
> code is licensed with the University of Illinois Open Source License).
> Will the LLVM project accept a backend with code licensed under this BSD
> license?  We would prefer to keep this license, but if it isn't
> acceptable, we can try to relicense it.
>
> Second, I am looking for two categories of feedback for the r600 backend:
>
> 1. What changes do I need to make to get the backend included in the LLVM
tree.
> 2. What changes can I make to improve the backend overall.
>
> My top priority is to get the backend into the LLVM tree, so
> when you provide feedback if you could be clear about what
> changes are needed to get the backend into the tree versus what changes
> are just general improvements, I would appreciate it.
>
> Lastly, I did a very brief run through of the code to check the coding
style,
> but I know there are still some violations.  For example, a lot of the
> file headers are missing file descriptions.  I didn't want to spend a
> lot of time on coding style changes prior to the initial review in case
> I was asked to make big changes to the code, so I will address these
> issues once I have received an OK on the organization of the code.
> However, please still point out coding style errors to me, and I'll be
> sure to fix them during the final pass.
>
> Looking forward to your feedback.
>
Hi,

Based on some feedback I received on IRC today, it sounds like this
is just too much code to review at once.  I'm going to try to strip
the R600 backend down to the bare minimum that is needed for our Mesa
drivers and then repost the code to the list.  Hopefully, this will make it
easier for people to review.

-Tom
_______________________________________________
LLVM Developers mailing list
LLVMdev at cs.uiuc.edu<mailto:LLVMdev at cs.uiuc.edu>        
http://llvm.cs.uiuc.edu
http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev



--
Thanks,

Justin Holewinski

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