Re: question about linker

On 04/12/2024 23:48, Scott Lurndal wrote:

David Brown <david.brown@hesbynett.no> writes:

On 04/12/2024 17:55, Scott Lurndal wrote:

13 minutes by the wall clock, a bit over an hour
of CPU time.
>

>
Is that a "typical" build - or an atypical full clean build?
>

 That was a build that touched a key header file, so maybe
85% full.  A full build adds a minute or two wall time.
 A single source file build (for most source files) takes
about 28 seconds real, a large portion of that in make as it
figures out what to rebuild in a project with thousands
of source files and associated dependencies.

That sounds like your dependency handling in make is not ideal.  Store your dependencies in individual files per source file, where both the object file and the dependency file itself are dependent on the headers used by the C file.  (The makefile should also have both the object file and the dependency file dependent on the C source file.)
Thus your build only generates new dependency files when either the C source file changes, or any of the headers included (recursively) by that C file change.  Change a C file, and it's dependencies will be re-calculated - but not the dependencies for anything else.  Change a header, and you only need to re-calculate the dependencies for the source files that actually use it.