[llvm-dev] [LLD] Slow callstacks in gdb

Rui Ueyama via llvm-dev llvm-dev at lists.llvm.org
Mon Nov 27 08:04:41 PST 2017

I do not know what is going on with your binary, but I'd first inspect
section sizes. Can you run `readelf --sections` against the two executable
to see if there's significant difference in section size?

On Mon, Nov 27, 2017 at 7:00 AM, Martin Richtarsky <s at martinien.de> wrote:

> Hi,
> for programs linked with lld it's substantially slower to get callstacks
> in gdb, in comparison to gold-linked programs. Two measurements:
> lld     gold
> 15 sec  3 sec
> 6 sec   2 sec
> This is a debug build, rather large binaries (lots of templates). I have
> seen even worse performance for debug+UBSan builds. I think code size (and
> therefore DWARF size) has an impact. Is there some information missing
> that gdb needs, and only gold generates?
> gdb version is 8. I tested lld 5.0 and an earlier 4.0 trunk version.
> Note that these binaries do not use gdb indexing.
> Has anyone seen something similar?
> Best regards,
> Martin
> --
> http://www.productive-cpp.com/
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