clang vs gcc build performance (executable not build time)

[Caolán McNamara]

On Tue, 2021-11-23 at 17:11 +0100, Luboš Luňák wrote:
> > 
> 
>  We don't use -Os, at least my local optimized build doesn't. A bunch
> of solenv/gbuild/platform files do set it, but it doesn't get selected
> here.

>  And according to logs those -Os come from at least 10 years ago, so if
> the idea is to use them, maybe it would be a good idea to re-check the
> effect they have.

We've used -O2 for x86_64 since:

6f335e555da5c14e43d3fdaeb90bcecc80ea4272
"2006/03/06 11:47:01 kendy 1.5.76.1: #i62814#
x86-64: -O2 instead of -Os for the optimized builds"

x86 was -Os back then, and still is. The rest of the platforms using
-Os are probably just cnp or a general vague feeling that -Os is a good
choice for limited hardware.