[PATCH] D44338: [LV][VPlan] Build plain CFG with simple VPInstructions for outer loops.

[Adrian Prantl via Phabricator via llvm-commits]

aprantl added a comment.

In https://reviews.llvm.org/D44338#1094030, @fhahn wrote:

> In https://reviews.llvm.org/D44338#1093996, @dcaballe wrote:
>
> > Thanks, Florian! Some comments below.
> >
> > > One thing worth discussing briefly before this goes in may be what the plan for dealing with debug info will be with VPlan. Adding @aprantl in case he has some thoughts.
> >
> > I'm not aware of any particular proposal for debug info in VPlan at this point but I will check with my team. Currently, DbgInfoIntrinsic would be represented as a regular VPInstruction. We could think about if a specific representation for this is necessary in VPlan.
>


Can you outline what would make updating dbg.value intrinsics to point to vector instructions special, such that it can't be handled immediately?

> Great thanks. Besides the DbgInfoIntrinsics,  do we need some way to attach the debug metadata from the original instructions to the VPInstructions? I suppose initially we could get them from the underlying values, but IIUC some VPlan transformations could introduce new VPInstructions without underlying values.

Similarly, when you expand/rewrite an instruction with a DILocation metadata attachment into a new instruction, preserving the metadata is crucial for accurate crash logs, profiling, and debugging in general. Speaking from personal experience here, it is usually much easier to think about this in the beginning rather than having to bolt it on later when the original transformation pass authors have moved on :-)


https://reviews.llvm.org/D44338