llvm dev - Jul 2009 - [LLVMdev] Writing pass for llc

Is there a beginner's tutorial/documentation on how to write passes
for the llc tool?  I've managed to write some simple analysis passes
for the opt tool but can't figure out how to do the same for llc.
What is the proper way to integrate a new MachineFunction pass with
llc?  Is there a way to register passes and selectively enable them on
the command line (as with opt) or do I need to hard code it into
llc.cpp?

I would like to be able to write a pass that looks at MachineFunctions
and inserts instructions right before register allocation (but after
all other optimization/instruction selection passes).  Any direction/
advice would be of great help.  Thanks!

On Sun, Jul 12, 2009 at 2:09 PM, shu<shuguang.feng at gmail.com>
wrote:
> Is there a beginner's tutorial/documentation on how to write passes
> for the llc tool?  I've managed to write some simple analysis passes
> for the opt tool but can't figure out how to do the same for llc.
> What is the proper way to integrate a new MachineFunction pass with
> llc?  Is there a way to register passes and selectively enable them on
> the command line (as with opt) or do I need to hard code it into
> llc.cpp?
>
> I would like to be able to write a pass that looks at MachineFunctions
> and inserts instructions right before register allocation (but after
> all other optimization/instruction selection passes).  Any direction/
> advice would be of great help.  Thanks!
llc uses Target.addPassesToEmit* interface to add passes. You can
insert your pass at appropriate place here.

-
Devang

Devang Patel wrote:
> On Sun, Jul 12, 2009 at 2:09 PM, shu<shuguang.feng at gmail.com>
wrote:
>   
>> Is there a beginner's tutorial/documentation on how to write passes
>> for the llc tool?  I've managed to write some simple analysis
passes
>> for the opt tool but can't figure out how to do the same for llc.
>> What is the proper way to integrate a new MachineFunction pass with
>> llc?  Is there a way to register passes and selectively enable them on
>> the command line (as with opt) or do I need to hard code it into
>> llc.cpp?
>>
>> I would like to be able to write a pass that looks at MachineFunctions
>> and inserts instructions right before register allocation (but after
>> all other optimization/instruction selection passes).  Any direction/
>> advice would be of great help.  Thanks!
>>     
>
> llc uses Target.addPassesToEmit* interface to add passes. You can
> insert your pass at appropriate place here.
>
> -
> Devang
>
>   
One related question.
Can we write CallGraphSCCPass in llc?

- Sanjiv

Thanks Devang.  A former office mate pointed me toward the
LLVMTargetMachine::addPreRegAlloc() function.  I appreciate your quick
response!

-shuguang

On Jul 14, 2:06 pm, Devang Patel <devang.pa... at gmail.com>
wrote:
> On Sun, Jul 12, 2009 at 2:09 PM, shu<shuguang.f... at gmail.com>
wrote:
> > Is there a beginner's tutorial/documentation on how to write
passes
> > for thellctool?  I've managed to write some simple analysis passes
> > for the opt tool but can't figure out how to do the same forllc.
> > What is the proper way to integrate a new MachineFunction pass with
> >llc?  Is there a way to register passes and selectively enable them on
> > the command line (as with opt) or do I need to hard code it into
> >llc.cpp?
>
> > I would like to be able to write a pass that looks at MachineFunctions
> > and inserts instructions right before register allocation (but after
> > all other optimization/instruction selection passes).  Any direction/
> > advice would be of great help.  Thanks!
>
> llcuses Target.addPassesToEmit* interface to add passes. You can
> insert your pass at appropriate place here.
>
> -
> Devang
>
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