Re: [PATCH/committed] sim: touch modules target

[Mike Frysinger via Gdb-patches <gdb-patches@sourceware.org>]

On 08 May 2021 14:49, Tom Tromey wrote:
> >>>>> "Mike" == Mike Frysinger via Gdb-patches <gdb-patches@sourceware.org> writes:
> 
> Mike> If there are no updates to the file, touch the result so we don't
> Mike> keep trying to regenerate it.
> 
> Normally you don't want to do it this way.  I think it will result in
> recompilations if the inputs change but the output does not.  Since it
> depends on Makefile and all the source files, this may be pretty often.
> 
> Now, if that's ok with you, it's simpler to just replace the
> move-if-change with a $(MV).
> 
> The more common approach is to use a stamp file.  So you write:
> 
> modules.c: modules-c-stamp ; @true
> modules-c-stamp: ... the existing code, but also touch modules-c-stamp
> 
> There are a few examples of this idiom already in the tree.  hw-config.h
> uses this, in the same file.  You'd also want to add the stamp file to
> the clean rule.

thanks, i'll take a look.  i was trying trying to figure out how to use this
thing correctly to avoid the rebuilds.
-mike