[libcxx-commits] [PATCH] D128146: [libc++] Use uninitialized algorithms for vector

Fri Jul 22 09:18:45 PDT 2022

joanahalili added a comment.

In D128146#3671966 <https://reviews.llvm.org/D128146#3671966>, @alexfh wrote:

> In D128146#3671687 <https://reviews.llvm.org/D128146#3671687>, @ldionne wrote:
>
>> In D128146#3671442 <https://reviews.llvm.org/D128146#3671442>, @hans wrote:
>>
>>> In Chromium we noticed that this adds 65 MB of debug info to one of our binaries (we noticed because that pushed it over the 4GB limit, so we'll need to do something about that anyway).
>>
>> Now, that is an actual issue that mandates our attention. Thanks for the heads up. I suspect it has to do with the fact that we instantiate more templates before we get to the `memmove` optimization in `std::copy`. @hans Do you have any way to tell what's in the 65 MB of debug information? Or a reproducer so we can try a few things out and see what impact it has on the size of the debug info? I assume this problem wouldn't be visible on a simple reproducer hand-written from scratch.
>>
>> @philnik Let's re-land this with an XFAIL for the LLDB test and work with the Chromium folks to decrease the amount of debug information this creates. We can do this after the release and cherry-pick back the improvements.
>
> It's not just Chromium, btw. We're seeing more fallout from to this commit. My teammates will post specific findings a bit later today.

Hi,

We are seeing some binary size increase of 2-3% because of this commit. The binary size increases are due to debug information section increases and also text section increases. 
Text section sizes increases  between 1-2%.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D128146/new/

https://reviews.llvm.org/D128146