[LLVMdev] Processing functions in call graph SCC "order" with function-level analyses

[John Criswell]

On 5/19/15 10:04 AM, Félix Cloutier wrote:
> Thanks John.
>
> Does this solve the problem of analysis availability though? If I 
> still have to run the function analyses manually, I might as well keep 
> rolling with the CallGraphSCCPass. (I probably should have mentioned 
> that this is what I’m using right now.)

I'm not sure what you mean by "manually."  If you use a ModulePass, you 
can use the getAnalysis<FunctionPassName>(F) method to get a reference 
to a function pass.  The ModulePass's getAnalysisUsage() method will 
need to use addRequired<FunctionPass>() to require each FunctionPass, 
but I think the PassManager will run the passes automatically as needed.

Note that you cannot use the PassManager to ensure that certain 
optimization passes are run before your pass is run.  If you need to run 
an optimization pass before your pass (e.g., UnifyExitNodes), then you 
need to tell the PassManager to run it before your pass explicitly.

Regards,

John Criswell

>
> Félix
>
>> Le 2015-05-19 à 10:12:32, John Criswell <jtcriswel at gmail.com 
>> <mailto:jtcriswel at gmail.com>> a écrit :
>>
>> On 5/18/15 10:45 PM, Félix Cloutier wrote:
>>> Hi all,
>>>
>>> I have one analysis pass that I want to perform on call graph SCCs. 
>>> However, for each function in the SCC, I need function-level 
>>> analyses, like the dominator tree and the memory dependency analysis.
>>>
>>> I’ve been told before 
>>> <http://stackoverflow.com/questions/30059622/using-dominatortreewrapperpass-in-callgraphsccpass> that 
>>> these were not available from a CallGraphSCCPass. What would be the 
>>> best approach for me to access this information? Should I run the 
>>> passes manually, or is there another, more pass-scheduler-friendly 
>>> approach?
>>
>> I would write a ModulePass that simply iterates over the call graph.  
>> LLVM provides a CallGraph analysis which one can use to find SCCs; 
>> DSA has an analysis called CallTargets which does "real" CallGraph 
>> analysis (which means that it tries to reason about function 
>> pointers, though I cannot guarantee that its reasoning will be as 
>> accurate as you want).
>>
>> If you use a ModulePass, can you analyze any part of the program you 
>> like, and you can use FunctionPasses.
>>
>> Regards,
>>
>> John Criswell
>>
>>>
>>> Félix
>>>
>>>
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> LLVMdev at cs.uiuc.edu          http://llvm.cs.uiuc.edu
>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>
>>
>> -- 
>> John Criswell
>> Assistant Professor
>> Department of Computer Science, University of Rochester
>> http://www.cs.rochester.edu/u/criswell
>


-- 
John Criswell
Assistant Professor
Department of Computer Science, University of Rochester
http://www.cs.rochester.edu/u/criswell

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20150519/b4b98d5d/attachment.html>