[PATCH] D64630: [DebugInfo] Address performance regression with r364515

[Jeremy Morse via Phabricator via llvm-commits]

jmorse added a comment.

Happily D58453 <https://reviews.llvm.org/D58453> killing off a large amount of placeDbgValues activity significantly reduces DBG_VALUE grouping -- I don't have the numbers to hand, but I would say the density was almost an order of magnitude lower. The largest back in the benchmark I referred to was about ~120, and other large packs occurred much less frequently.

Reid wrote:

> dbg.value packs are a major issue, ASan aside. I wrote this proposal a while back and never followed through on it:
>  http://lists.llvm.org/pipermail/llvm-dev/2018-October/127228.html
> 
> With the lack of follow-through on my part, I think we should take Chris's suggestion of changing our representation to multiplex dbg.value, so that one instruction can describe an arbitrary number of variable locations without increasing the number of instructions that other passes have to iterate over.

While this review isn't the place, this is definitely an area I'd want to invest time into, debug-info in the instruction stream is a frequent pain.


Repository:
  rL LLVM

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https://reviews.llvm.org/D64630