Manideepa Mukherjee
2015-Jul-29 06:42 UTC
[LLVMdev] Loop Dependence Analysis(getDistance())
Hi,
I am trying to use the DependenceAnalysis pass to get the Distance vector
for the innermost loop. I am in LLVM learing process. I have used the
following code inside my original code to get the distance vector. It is
not giving any syntax error but it is has some logical but and giving
segmentation fault.
void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
AU.addRequired<PostDominatorTree>();
AU.addRequired<LoopInfo>();
AU.addRequired<DependenceAnalysis>();
AU.addPreserved<DependenceAnalysis>();
AU.addRequired<ScalarEvolution>();
AU.addPreserved<ScalarEvolution>();
AU.addRequired<AliasAnalysis>();
AU.addPreserved<AliasAnalysis>();
AU.addRequired<MemoryDependenceAnalysis>();
AU.addPreserved<MemoryDependenceAnalysis>();
}
In runOnFunction I have used dependence
&getAnalysis<DependenceAnalysis>();
if(L->getSubLoops().size()==0)
{ Dependence* dependence;
const SCEV* scev = dependence->getDistance(loopID);
....
................
.............
}
loopID is and unsigned int variable which I have increased after each time
after doing some other operations on loop like printing the basic block of
each loop.
Is this the correct way to do it. Any example would be a great help for me
to understand this. For a loop how can I print the distance vector using
getDistance(). I have tried the da pass which worked fine for the example
given in this
http://comments.gmane.org/gmane.comp.compilers.llvm.devel/55437 link.
please help.
--
Thanks & Regards,
Manideepa Mukherjee
Contact No:- +91-7428062726
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In the example you provided, the author uses the DependenceAnalysis to retrieve a dependence for the src and dest instructions. Note the line: dependenceAnalysis->depends(instructions[src], instructions[dst], true); Without really exploring much I think you should note that getDistance is a function of the Dependence class and not DependenceAnalysis. You need to retrieve a dependence or dependencies to operate with getDistance. In your code you're just pulling the Analysis information and immediately attempting to retrieve the distance. It might help to take a look at how DependenceAnalysis and getDistance are used in: lib/Transforms/Scalar/LoopInterchange.cpp Jake On Tue, Jul 28, 2015 at 11:42 PM, Manideepa Mukherjee < manideepa.mukherjee at gmail.com> wrote:> Hi, > > I am trying to use the DependenceAnalysis pass to get the Distance vector > for the innermost loop. I am in LLVM learing process. I have used the > following code inside my original code to get the distance vector. It is > not giving any syntax error but it is has some logical but and giving > segmentation fault. > > void getAnalysisUsage(AnalysisUsage &AU) const { > AU.setPreservesAll(); > AU.addRequired<PostDominatorTree>(); > AU.addRequired<LoopInfo>(); > AU.addRequired<DependenceAnalysis>(); > AU.addPreserved<DependenceAnalysis>(); > AU.addRequired<ScalarEvolution>(); > AU.addPreserved<ScalarEvolution>(); > AU.addRequired<AliasAnalysis>(); > AU.addPreserved<AliasAnalysis>(); > AU.addRequired<MemoryDependenceAnalysis>(); > AU.addPreserved<MemoryDependenceAnalysis>(); > } > > In runOnFunction I have used dependence > &getAnalysis<DependenceAnalysis>(); > if(L->getSubLoops().size()==0) > { Dependence* dependence; > const SCEV* scev = dependence->getDistance(loopID); > .... > ................ > ............. > } > loopID is and unsigned int variable which I have increased after each time > after doing some other operations on loop like printing the basic block of > each loop. > > Is this the correct way to do it. Any example would be a great help for me > to understand this. For a loop how can I print the distance vector using > getDistance(). I have tried the da pass which worked fine for the example > given in this > http://comments.gmane.org/gmane.comp.compilers.llvm.devel/55437 > <https://urldefense.proofpoint.com/v2/url?u=http-3A__comments.gmane.org_gmane.comp.compilers.llvm.devel_55437&d=AwMFaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=Mfk2qtn1LTDThVkh6-oGglNfMADXfJdty4_bhmuhMHA&m=qQylmJlO7KBr1bWLPo0kow2CiegPX7dhwSWuMwIVd3Y&s=vrl-8n0v-s7TeSDdYauMvjD8mNPAR0MqB1TEILSFxgU&e=> > link. please help. > > > -- > Thanks & Regards, > Manideepa Mukherjee > Contact No:- +91-7428062726 > > _______________________________________________ > LLVM Developers mailing list > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev > >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20150729/5d4e37cc/attachment.html>