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

Tue Jun 18 05:51:10 PDT 2019

ruiu added a comment.

In D63344#1548151 <https://reviews.llvm.org/D63344#1548151>, @thakis wrote:

> In D63344#1548150 <https://reviews.llvm.org/D63344#1548150>, @ruiu wrote:
>
> > In D63344#1548106 <https://reviews.llvm.org/D63344#1548106>, @thakis wrote:
> >
> > > > How long is the increase?
> > >
> > > That's a good question. Intuitively I'd say it shouldn't be all that much: Undefined diags were emitted doing relocation scanning, which I think happens fairly late in the link, and now it happens after it. So the max latency added is the time it takes to scan relocations. I'd expect that relocation scanning time is small compared to total link time. But I'll measure and report back.
> >
> >
> > Thanks. I have a feeling that the relocation scan pass is one of the heaviest pass in lld, so it's worth measuring.
>
>
> I hooked up the ScopedTimer stuff that lld/COFF uses to lld/ELF (if there's interest, I can send a patch for that), and here's the output for linking libblink_core.so in a debug build:
>
>     Reloc scanning:               239 ms (  4.0%)
>   -------------------------------------------------
>   Total Link Time:               5975 ms (100.0%)
>

Ah, this number seems completely acceptable. Thank you very much for measuring it.

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