On Thu, 17 Jul 2025 at 18:05, Pierrick Bouvier
<pierrick.bouv...@linaro.org> wrote:
> On 7/17/25 9:56 AM, Peter Maydell wrote:
> > I'm not really a fan of relying on the compiler to fold stuff
> > away -- it's fragile and there's no guarantee the compiler
> > will actually do it. In this example it would be really easy
> > for somebody coming along to tidy this up later to put the
> > nested if()s back into a single if() condition and reintroduce
> > the problem, for instance.
> >
>
> There are various places where we already relied on that, including
> before the single-binary work ({accel}_allowed).
>
> For the fragile aspect of it, that's why CI exists. Building all
> binaries with clang --enable-debug should ensure no regression can be
> introduced.But our CI can't check all versions of gcc and clang at all optimisation levels. The reason it's fragile is because there's never a guarantee that the compiler does it or what situations it will work vs not work. It's not a feature provided by the language or the compiler that you can fold away references to functions that don't exist; it just happens to work. I know we already rely on constant-folding in various places: I'm not super enthusiastic about those either. -- PMM
