[PATCH] D63344: lld/elf: Deduplicate undefined symbol diagnostics

Tue Jun 18 06:10:06 PDT 2019

ruiu added a comment.

In D63344#1548162 <https://reviews.llvm.org/D63344#1548162>, @thakis wrote:

> For a static debug build of chrome (since the link time is a bit long, this configuration isn't officially supported and hits an assert("don't use this config") that I commented out):
>
>     Reloc scanning:              1304 ms (  7.0%)
>   -------------------------------------------------
>   Total Link Time:              18744 ms (100.0%)
>
>
> So it's not nothing, but it's also < 10 %, and this isn't link slowdown but latency for seeing undefined symbol diagnostics. Personally, I've never started looking at undefined symbols while they're still scrolling by, and latency for being done with printing undefined symbols is unchanged. So I'd say this is fine, but it's a bit of a judgement call.

I'd think that what you should actually compare is the time to get an error message before this patch and after this patch, instead of the total link time. If lld spends zero time before relocation processing (which is unrealistic but just an example), users would have been able to get an error message immediately (assuming that relocations errors are everywhere) and they would have to wait 1300 ms after this patch.

But if you wait for 10 seconds for lld to start relocation processing, additional 1 second may not be a big deal.

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https://reviews.llvm.org/D63344