[PATCH] D65178: WIP: [DWARF] Collect statistics for DW_OP_entry_value

Wed Jul 24 08:29:39 PDT 2019

vsk abandoned this revision.
vsk added a comment.

In D65178#1598514 <https://reviews.llvm.org/D65178#1598514>, @djtodoro wrote:

> @vsk Thanks for this! We have discussed about this on the other threads and the stats is useful for sure! 
>  Having this stats gives us info about the "normal" (non-entry values) debug location coverage, because those locations with the entry value are useless if do not have proper **call_site** and **call_site_paramters** debug information generated in the **.debug_info** section.
>
> WDYT about having a separate tool that will calculate and report more (verbose) info about the debug location coverage? I have already mentioned it on the D58042 <https://reviews.llvm.org/D58042> and the link of the 'WIP' of the tool is https://github.com/djolertrk/llvm-locstats.
>  We can play with that and add more options we found useful for us.

Thanks for the link. I’ll set this patch aside for now. Maybe any relevant parts can be folded into the locstats tool later.

Copying some discussion with Eric about the goals of this:

On Jul 23, 2019, at 9:31 PM, Eric Christopher wrote:

I guess? I'm curious what we'd get out of it in general? Is the
thought that we could try to classify how often we have to do more
work to recover parameters? Not against it, just trying to see why :)

Vedant:
I’d like to get the percentage of parameters guaranteed to have an available location.

I think this should correlate with backtrace quality (if not, that’s interesting too, maybe it means the debugger has bugs).

Counting entry_value descriptions is a starting point, but I think you’d need to check that the ranges in a parameter location description span the whole function to finish the patch.

As-is, I thought “# entry values” could be fun to look at as the callsiteparam work lands.

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