[LLVMdev] LoopInfo of a basic block

[Devang Patel]

On Feb 28, 2011, at 2:35 PM, Naznin Fauzia wrote:

> Hi all,
> 
> How Can I get the Loops around an Instruction?
> 
> I know I can get the basic block of an instruction using inst.getParent() which returns a BasicBlock*. Now I want to use the getLoopFor(BasicBlock) method of the class LoopInfo.
> But I dont know how to get the LoopInfo.
> 
> BasicBlock* bb = inst.getParent();
> 
> (... what should I add here?)
> 
> Loop* innerloop = LI -> getLoopFor(bb):
> 

Two steps:
1) In your pass's getAnalysisUsage(), request LoopInfo.

	virtual void getAnalysisUsage(AnalysisUsage &AU) const {
	  AU.addRequired<LoopInfo>();
	}

2) In your runOnLoop() method get the analysis.

	LoopPass *LI = &getAnalysis<LoopInfo>();

Now, you can do LI->getLoopFor(...)

-
Devang


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