On Fri, Dec 04, 2020 at 07:16:45PM +0100, Andrea Corallo via Gcc-help wrote:
> Segher Boessenkool <segher@xxxxxxxxxxxxxxxxxxx> writes:
>
> > On Fri, Dec 04, 2020 at 10:52:17AM +0100, Andrea Corallo via Gcc-help wrote:
> >> stefan@xxxxxxxxx writes:
> >> I might open a bug but my understanding is that const is generally
> >> not used for optimizations. Am I wrong?
> >
> > extern const int x = 42;
> > int f(void) { return x; }
> >
> > The code generated for f does not load the value for x from memory: it
> > returns 42 always.
> Are you suggesting we should treat this as a bug?
Huh? No, I am just saying that const *is* used for optimisation, with a
dumb simple example. Remove const from this code and you get different
generated machine code (that does load x from memory always).
If you think you have found a missing optimisation, please make a
self-contained demonstrator for that, and a file a PR?
Segher
