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Re: Slim lto objects


> Hi,
> I build Mozilla without debug info with slim LTO and non-LTO.
> slim LTO build is:
> 
> real    14m26.882s
> user    78m47.547s
> sys     6m58.870s
> jh@evans:/abuild/jh/build-mozilla-new14> du -s .
> 1056120 .
> jh@evans:/abuild/jh/build-mozilla-new14> size toolkit/library/libxul.so
>    text    data     bss     dec     hex filename
> 46552709        3585416  381640 50519765        302ded5 toolkit/library/libxul.so
> 
> non-LTO build is:
> real    13m19.251s
> user    61m21.386s
> sys     7m28.672s
> jh@evans:/abuild/jh/build-mozilla-new14-no-lto> du -s .
> 424224  .
> jh@evans:/abuild/jh/build-mozilla-new14-no-lto> size toolkit/library/libxul.so
>    text    data     bss     dec     hex filename
> 32403100        2659736  385224 35448060        21ce4fc toolkit/library/libxul.so

And fat lto build
real    21m43.009s
user    101m43.305s
sys     8m40.085s
jh@evans:/abuild/jh/build-mozilla-new14-fatleto> du -s . 
1173900 .
jh@evans:/abuild/jh/build-mozilla-new14-fatleto> size toolkit/library/libxul.so 
   text    data     bss     dec     hex filename
35374139        2908088  380584 38662811        24df29b toolkit/library/libxul.so

fat and slim LTO binary should really be equilvalent, so something is wrong.  I can only
think of confused symbol tables in static libraries or so.
Will try to work out what happens.

Also fat LTO and non-LTO Mozilla performs better than slim LTO build.

Honza


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