Re: How to speed up 'automake'

[Jan Engelhardt]

On Monday 2022-05-02 15:18, Bob Friesenhahn wrote:
> On Mon, 2 May 2022, Jan Engelhardt wrote:
>>
>> Indeed, if a source code package consists of 10000 files, then configure
>> produces another 10k files for the stuff in the ".deps" directories.
>> There is not much autotooling can do here, as I believe pregenerating
>> those 10k files all with "# dummy" content is to support the least common
>> demoniator of /usr/bin/make.
>
> In a configure script I see the option:
>
>  --disable-dependency-tracking
>                          speeds up one-time build
>
> so what tangible benefits does --disable-dependency-tracking actually provide?

I remember that option. That disables .deps entirely or so.
Distributions, including openSUSE use it because they (barring
exceptional circumstances) do not modify (non-BUILT_SOURCES) source
files between two invocations of make.

Great for the ephmereal build root that was initially talked about,
not so cool for developers that switch between editor and compiler
every so often :)


> If empty files are ok (assuming they are needed at all), can they be produced
> with a minimum number of executions of a 'touch' command?

Better yet, they can be produced with the ">>" shell builtin, skipping
spawning the touch program. (We need to use >>, because > truncates,
and configure does not truncate deps files for a good reason - doing
so would be like `make clean`)