[FFmpeg-devel] [PATCH 1/3 v2] configure: speedup x2-x8

avih avihpit at yahoo.com
Sat Aug 25 21:42:48 EEST 2018


It turns out the the output order of "unique()" was important, andfailing to keep the original order (where it keeps the last instanceof recurring items) caused some linkage failures.

This Patch 1/3 v2 squashes opt1-reorder-unique.patch onto the originalpatch 1/3, and updates the commit message accordingly.
It fixes the linkage failures mentioned at:http://ffmpeg.org/pipermail/ffmpeg-devel/2018-August/233674.html
 

    On Saturday, August 25, 2018 9:09 PM, avih <avihpit-at-yahoo.com at ffmpeg.org> wrote:
 

 For overview see:
http://ffmpeg.org/pipermail/ffmpeg-devel/2018-August/233665.html

Attached is patch 1/3 which was at "main.patch" of that message.

About 50-70% of configure runtime was being spent inside one
function: flatten_extralibs() and callees resolve() and unique().
It manipulates strings and invoked nearly 20K (20000) subshells.
It was rewritten to avoid subshells, and ended up x50-x250 faster.

unique() now outputs a different order:
it was keeping the last instance of recurring items, now it
keeps the first. It affects libs order at ffbuild/config.{mak,sh} -
but I don't think it matters. If it does, "opt1-reorder-unique.patch"
restores the original order. Let me know if/why it matters and I'll
squash it and update the commit message accordingly if required.
 

    On Saturday, August 25, 2018 7:55 PM, Timo Rothenpieler <timo at rothenpieler.org> wrote:
 

 Please use git send-email to send your patches, or at least send each 
patch, created by git format-patch, as individual attachment. Your files 
seem to contain multiple patches one after another, which makes them 
very hard to follow.

But nice work! Let's hope this does not cause any regressions.
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