https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119823
Manuel López-Ibáñez <manu at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |manu at gcc dot gnu.org
--- Comment #1 from Manuel López-Ibáñez <manu at gcc dot gnu.org> ---
(In reply to sandra from comment #0)
> At optimization levels below -O1 or -Og, the pass manager completely skips
> most optimization passes regardless of whether the corresponding option for
> that pass is set. In common.opt many of the corresponding optimization
> options are specified with Init(1), e.g. -fivopts (PR71094), and the -Q
> option duly reports that they are enabled at -O0, which they are not. We
> should fix this. Probably it involves adding some additional flag to
> common.opt and making the -Q printer do something with it.
>
> We've also got a problem that it's hard to sync the manual's lists of
> options enabled at different levels with reality. It would be great if we
> could get -Q to produce a list that could be cross-checked with the manual,
> or for the options processing during GCC build to emit some text that could
> be inserted directly in the manual.
Yes please.
The options machinery should be able to detect whether an option has a default
value or a value explicitly set by the user. It currently uses the trick of
setting the default value to -1, which is a waste.
An example from common.opt is
```
fprefetch-loop-arrays
Common Var(flag_prefetch_loop_arrays) Init(-1) Optimization
Generate prefetch instructions, if available, for arrays in loops.
```
But this should be something like:
```
fprefetch-loop-arrays
Common Var(flag_prefetch_loop_arrays) Init(O2 | O3) Optimization
Generate prefetch instructions, if available, for arrays in loops.
```
