Re: GNAT and register allocation

[Georg Bauhaus <rm.dash-bauhaus@futureapps.de>]

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.

>> 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.

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