[LLVMdev] How to uniquely remember a loop?

[Andrew Trick]

On Aug 21, 2012, at 4:17 AM, "Rao, Prashantha" <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
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