llvm dev - Jul 2017 - Making an analysis availble during call lowering

Hi,


I want to be able to access a custom analysis pass during call lowering, but
there isn't a way to access this now and I'm not sure the least bad way
to thread this information into the DAG.


I want to be able to use knowledge of the callee function to change the lowering
of a call. Since AMDGPUDAGToDAGISel is ultimately a normal MachineFunction pass,
I'm able to get the interprocedural analysis pass there but don't have a
way to pass this into the call lowering where it's actually needed.


The laziest option would be to stash the pointer to the analysis in the
TargetMachine and get it from there, but is probably not the best idea. Another
option might be to store a pointer to the SelectionDAGISel pass in SelectionDAG,
so then there's a way to access the pass to get analysis directly. Is there
another option?


-Matt

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On 06/13/2017 12:46 PM, Arsenault, Matthew via llvm-dev
wrote:
>
> Hi,
>
>
> I want to be able to access a custom analysis pass during call 
> lowering, but there isn't a way to access this now and I'm not sure
> the least bad way to thread this information into the DAG.
>
>
> I want to be able to use knowledge of the callee function to change 
> the lowering of a call. Since AMDGPUDAGToDAGISel is ultimately a 
> normal MachineFunction pass, I'm able to get the interprocedural 
> analysis pass there but don't have a way to pass this into the call 
> lowering where it's actually needed.
>
>
> The laziest option would be to stash the pointer to the analysis in 
> the TargetMachine and get it from there, but is probably not the best 
> idea. Another option might be to store a pointer to the 
> SelectionDAGISel pass in SelectionDAG, so then there's a way to access 
> the pass to get analysis directly. Is there another option?
>
With the legacy pass manager, are you planning to schedule the analysis 
pass manually and then use getAnalysisIfAvailable?

Thanks again,
Hal
>
> -Matt
>
>
>
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
-- 
Hal Finkel
Lead, Compiler Technology and Programming Languages
Leadership Computing Facility
Argonne National Laboratory

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> On Jul 24, 2017, at 13:52, Hal Finkel via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> 
> On 06/13/2017 12:46 PM, Arsenault, Matthew via llvm-dev wrote:
>> Hi,
>> 
>> I want to be able to access a custom analysis pass during call
lowering, but there isn't a way to access this now and I'm not sure the
least bad way to thread this information into the DAG.
>> 
>> I want to be able to use knowledge of the callee function to change the
lowering of a call. Since AMDGPUDAGToDAGISel is ultimately a normal
MachineFunction pass, I'm able to get the interprocedural analysis pass
there but don't have a way to pass this into the call lowering where
it's actually needed.
>> 
>> The laziest option would be to stash the pointer to the analysis in the
TargetMachine and get it from there, but is probably not the best idea. Another
option might be to store a pointer to the SelectionDAGISel pass in SelectionDAG,
so then there's a way to access the pass to get analysis directly. Is there
another option?
> 
> With the legacy pass manager, are you planning to schedule the analysis
pass manually and then use getAnalysisIfAvailable?
> 
> Thanks again,
> Hal
> 
I didn’t need to do anything special. addRequired/getAnalysis work.

-Matt

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