[LLVMdev] How to uniquely remember a loop?

[Rao, Prashantha]

From: Andrew Trick [mailto:atrick at apple.com]
Sent: Tuesday, August 21, 2012 9:58 PM
To: Rao, Prashantha
Cc: llvmdev at cs.uiuc.edu
Subject: Re: [LLVMdev] How to uniquely remember a loop?

On Aug 21, 2012, at 4:17 AM, "Rao, Prashantha" <Prashantha.Rao at amd.com<mailto:Prashantha.Rao at amd.com>> wrote:
More than one loop may share the same header;

You have a different definition of loop than the rest of the optimizer. You can identify your loops by the backedge if you prefer.


I can certainly run LoopSimplify as a prepass. But will that ensure unique loop header for each loop.

It tries to split loops into single back edge loops. No guarantee.


As I will be performing transformation after the analysis other optimizations will not interfere (hopefully).

Now it sounds like you're writing a standard in-process Analysis pass that can be used by your transformation without being invalidated. If so, just refer directly to Loop* from LoopInfo.


Will the debug info metadata be available always?  If so, what are good pointers to explore?

Certainly no guarantee. Do you want your optimization to depend on debug info?

-Andy

Andy-

I will go with an Analysis phase followed by transformation phase and I will make LoopInfo run as prepass for analysis. That should make LoopInfo  valid when I run analysis and transform.

Thanks,
-Prashantha

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