Re: GNAT and register allocation

[Stephen Leake <stephen_leake@stephe-leake.org>]

Georg Bauhaus <rm.dash-bauhaus@futureapps.de> writes:

> On 25.04.12 13:51, Stephen Leake wrote:
>
>>> Yes, GNAT project files are understandable, though non-portable TTBOMK.
>> 
>> What do you mean by "portable" here?
>
> Portable from one compiler to another. The Ada programs typically
> are portable as-is.

Ok. But the C and Fortran compiler options are equally non-portable, so
I don't see this as significant.

>>> Gpr files will likely not be used by those who code for Intel's
>>> Fortran compiler, or the C part of GCC; they can easily specify
>>> IFCOPTS or GCCOPTS referenced in Makefiles.
>> 
>> Why is that relevant?
>
>> So if that gnatmake line includes -P<file>, and <file> is kept with the
>> rest of the Ada source code, what's the problem?
>
> The problem is that there exists a setup, and personnel (P), and
> (1) there is a script
> (2) that processes a .ini file (common to all languages)
> (3) runs a simple makefile injecting few variables from step (2)
> (4) for all languages (more than a dozen).
>
> In the interest of manageability and transparency to (P), things are
> to be kept simple and comparable, as far as I understand previous
> comments. The programs do change every now and then.
> The configuration files would have to change, too.
> Such changes need to be checked by (P), for all languages,
> in order to prevent anything that in effect violates some rules.

So the Ada programers are required to understand the C and Fortran
compiler options well enough to maintain them? And conversely, the C and
Fortran people are expected to maintain the Ada compiler options.

That doesn't sound reasonable to me.

I will grant that the gpr files are not as well documented as the
compiler options; it is not possible to determine which package should
contain any given compiler option.

If that were fixed, I think it's reasonable to expect anyone who can
maintain makefiles and compiler options in general to maintain gpr files.

And as I have said, in the long run everyone would gain if everyone
switched to gpr files.

> Ideally, settings commonly used by all compilers, such as "optimize",
> or "use this hardware",  will be sufficiently effective and understood
> by all compilers. 

Do you mean "spelled the same for all compilers" or "all compilers will
have an option similar enough in meaning". I'd expect the latter, but
not the former.

> In fact, an earlier version of the GNAT make rule had been referring
> to COPTS, which was -O3 -fomit-frame-pointer; the C++ rule did the
> same, I think. Fortran cannot refer to GCCish COPTS, since they
> switched to Intel Fortran.

And did anyone object to that "non-compatible options" change?

-- 
-- Stephe