Re: RFC: -Wall by default

[Robert Dewar <dewar at adacore dot com>]

> It's on my large TODO list, somewhere at the bottom, to propose
> to make -O1 stop after early optimizations and drop right to
> expansion from there.  That would turn optimization expectations
> upside-down of course, but early optimizations should be mostly
> reducing code size (and thus increase compile speed) with
> no fancy optimization that inhibit debugging (SRA, IPA-SRA,
> switch conversion and function splitting are an exception,
> but all but SRA are not enabled at -O1).  So we'd move to
> compile-time and debuggability for -O1 (I'd expect compile time
> that should be better or at least not a lot slower than -O0).

I am all in favor of such work, but I would approach it in two
steps. First make it a separate -O level, then depending on
how successful this is in practice, propose making -O1 mean
this new level.

If you do both steps at once, you get opposition on the basis
of change-is-bad, rather than to the substance of the new
level of optimization.
> Richard.