[m-rev.] for review: Defer SHARED_LIBS assignment in ml script.

[Zoltan Somogyi]

On 2023-12-14 15:27 +11:00 AEDT, "Peter Wang" <novalazy at gmail.com> wrote:
> On Thu, 14 Dec 2023 15:12:31 +1100 Julien Fischer <jfischer at opturion.com> wrote:
>> 
>> On Thu, 14 Dec 2023, Peter Wang wrote:
>> 
>> > scripts/ml.in:
>> >    Assign SHARED_LIBS only when it will actually be used,
>> >    as the default value of SHARED_LIBS set by configure
>> >    may invoke "gcc -print-libgcc-file-name" in a command substitution.
>> 
>> That's fine. Presuambly, this is just for performance reasons?
> 
> Yes, though I haven't tried to measure the difference.
> 
> I noticed it because nearly 80% the calls to ccache on my system were
> "Uncacheable" and, of those, 94% were due to "No input file" --
> likely most of those due to ml running "gcc -print-libgcc-file-name".

What do we gain by executing gcc --print-libgcc-file-name in the ml script at all?
Under what circumstances is its output going to change? Why can't we execute
that command in the configure script itself, and bake not the command, but
its *output* into the ml script?

Zoltan.