Re: cost of -MP

[Noel Yap]

Boris Kolpackov wrote:

> Noel Yap <address@hidden> writes:
>
>
> > Interesting, non-recursive was slower than recursive.  I suppose I can see 
> > this happening if there weren't that many directories in the project.  How 
> > many directories do you have?
>
> It is 19 make re-executions. The reason non-recursive is slower is that I 
> haven't had a chance to optimize it yet. I actually expect it to be faster 
> than recursive (for obvious reasons). 

OK, this makes sense.

> > Regarding the topic at hand, we don't use -MP, but post-process the output 
> > and create empty targets for the header files.  For example:
> >
> >        my_header:
>
> That's exactly what gcc does.

I misunderstood.  When you said PHONY targets, I thought you meant it generates 
".PHONY: my_header" as well, not just an empty target.

Noel