Re: GCC -ftime-trace

[Richard Biener <richard.guenther@gmail.com>]

On Sat, Feb 11, 2023 at 8:37 PM Basile Starynkevitch
<basile@starynkevitch.net> wrote:
>
> Hello all,
>
> Shivansh Khare wrote:
>
>
> > I have looked into the different starter projects that are offered in the
> > [Wiki GSoC page](https://gcc.gnu.org/wiki/SummerOfCode) and I was
> > particularly interested in the `-ftime-trace` project. The following is
> > what is given as a short description about the problematic:
> > "Implement something similar to Clang's -ftime-trace feature which
> > generates performance reports that show where the compiler spends compile
> > time. For more information, please check the following blog post.
>
> Are you aware of the existing -ftime-report option to GCC 12 or later?

It looks like -ftime-trace can be implemented ontop of the existing time
tracking that's reported with -ftime-report and -ftime-report-details, possibly
a first step would be to make the raw data more accessible.  We've now
not alternate output for various auxiliary data for example in JSON format,
so implementing -ftime-report=json plus an external visualization tool/script
might be a good start for the project.

Richard.

> On Linux (and probably many other POSIX) systems, at least in straight
> (non-cross) x86-64 GCC compilers, implementing that should be not very
> difficult. Here are some insights.
>
> Read carefully https://man7.org/linux/man-pages/man7/time.7.html
>
> First, you could experiment by writing a GCC plugin doing that timing
> (in some experimental way).
> https://gcc.gnu.org/onlinedocs/gccint/Plugins.html
>
> Maybe consider later providing such a "standard" GCC plugin to do the
> timing.
>
> Modifying the pass manager
> https://gcc.gnu.org/onlinedocs/gccint/Pass-manager.html#Pass-manager to
> use clock_gettime system call. See
> https://man7.org/linux/man-pages/man2/clock_gettime.2.html
>
> It is related to plugin gate functions...
>
>
> Regards.
>
>
> BTW, my pet open source project is http://refpersys.org/ (symbolic
> inference engine, work in progress).
>
>
> --
> Basile Starynkevitch                  <basile@starynkevitch.net>
> (only mine opinions / les opinions sont miennes uniquement)
> 92340 Bourg-la-Reine, France
> web page: starynkevitch.net/Basile/
>