From: Mandeep Sandhu <mandeepsandhu.chd@gmail.com>
To: gcc-help@gcc.gnu.org
Subject: Re: stdc++ issue: extremely long compile time with large number of string literals
Date: Thu, 9 Jul 2020 14:27:58 -0700 [thread overview]
Message-ID: <CAC+QLdQRO9Sbzi-xgeCE=7QFn7FeZFA96eX2PyMazwUohOca8g@mail.gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.23.453.2007092243400.6317@stedding.saclay.inria.fr>
> You didn't say what flags you are using. For anything autogenerated like
> that, going above -O1 is always risky.
I run it with just -std=c++11 (not optimization flag, so I guess it
defaults to -O0)
>
> One first thing to try is -ftime-report
>
> At -O0
> phase opt and generate : 3.46 ( 84%) 0.15 ( 45%) 3.62 ( 81%) 188385 kB ( 70%)
With 5000 strings, & -O0 I get the following in the time report:
Time variable usr sys
wall GGC
...
phase opt and generate : 4.12 ( 89%) 0.18 ( 46%)
4.30 ( 86%) 99680 kB ( 58%)
...
expand vars : 2.41 ( 52%) 0.00 ( 0%)
2.42 ( 48%) 699 kB ( 0%)
...
TBH, not sure what these values mean. Someone mentioned that overload
resolution might be causing the excessive delay, but I can't find any
metrics to verify that.
-mandeep
>
> without a specific pass that stands out.
>
> At -O1
> phase opt and generate : 87.96 ( 99%) 6.57 ( 97%) 94.56 ( 99%)24503776 kB (100%)
> callgraph ipa passes : 85.93 ( 97%) 6.52 ( 96%) 92.47 ( 97%)24413253 kB ( 99%)
> tree eh : 84.32 ( 95%) 6.43 ( 95%) 90.78 ( 95%)24340697 kB ( 99%)
>
> so, it looks related to the optimization of exceptions...
>
> --
> Marc Glisse
next prev parent reply other threads:[~2020-07-09 21:28 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-09 20:31 Mandeep Sandhu
2020-07-09 20:49 ` Marc Glisse
2020-07-09 21:27 ` Mandeep Sandhu [this message]
2020-07-09 23:49 ` Jonathan Wakely
[not found] ` <CAC+QLdRqjTe4YsUpQRcLG7tpxGda0oh6H788ORZa5MQR3NqRbw@mail.gmail.com>
[not found] ` <CAH6eHdTRiwA3t1K3okfVc+umPM8PJfbePaO7AHdLz+SYPOU9XQ@mail.gmail.com>
2020-07-10 19:36 ` Mandeep Sandhu
2020-07-10 20:25 ` Jonathan Wakely
2020-07-11 6:27 ` Mandeep Sandhu
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