Bug#684926: linux: disable CONFIG_CC_OPTIMIZE_FOR_SIZE

[Ben Hutchings <ben@decadent.org.uk>]

On Tue, Aug 14, 2012 at 09:56:17PM +0200, Christoph Anton Mitterer wrote:
> Source: linux
> Severity: wishlist
> 
> 
> Hi.
> 
> Is there any reasons why you've enabled CONFIG_CC_OPTIMIZE_FOR_SIZE?

This is the recommended default (though not the actual default).
 
> >From gcc:
> > Optimize for size.  -Os enables all -O2 optimizations that do not
> > typically increase code size.  It also performs further
> > optimizations designed to reduce code size.
> > -Os disables the following optimization flags: -falign-functions
> > -falign-jumps  -falign-loops -falign-labels  -freorder-blocks
> > -freorder-blocks-and-partition -fprefetch-loop-arrays
> > -ftree-vect-loop-version
> 
> 
> So we loose all kinds of optimisations just for storage, which really doesn't
> count on all but embedded systems.

Larger code results in more I-cache misses, so it can be slower after
all.

Let's see your benchmark results.

Ben.

-- 
Ben Hutchings
We get into the habit of living before acquiring the habit of thinking.
                                                              - Albert Camus