Re: Bug#456034: fenix: compile with -O1
On 14/12/2007, Simon Ruggier <firstname.lastname@example.org> wrote:
> On 12/14/07, Jon Dowland <email@example.com> wrote:
> > My understanding is that -O2 should never result in incorrect/failing
> > code and -O3 can, but I'm not sure where I get that notion frmo.
> I would have thought one would get it from the gcc man page, but when
> I looked, I couldn't find anything explicit.
It can be found through 'info': info gcc
Section: 3.10 Options That Control Optimization
Optimize even more. GCC performs nearly all supported
optimizations that do not involve a space-speed tradeoff. The
compiler does not perform loop unrolling or function inlining when
you specify `-O2'. As compared to `-O', this option increases
both compilation time and the performance of the generated code.
`-O2' turns on all optimization flags specified by `-O'. It also
turns on the following optimization flags:
Please note the warning under `-fgcse' about invoking `-O2' on
programs that use computed gotos.
Not sure if that helps.