0005-Search-all-dominated-blocks-for-expressions-to-hoist.patch

[Maxim Kuvyrkov]

On 6/24/10 12:49 AM, Steven Bosscher wrote:
...
> Actually the parameter also makes a difference for code size. When I
> experimented with this all this time ago, I had the best CSiBE size
> scores with a depth of 5 or 6.

Yes, I got similar results when tested this patch without max_distance 
restriction on expressions.  Depth of 5 or 6 avoids nasty regressions in 
code with high register pressure; with a greater depth all small 
expressions get hoisted to the first basic block and register pressure 
sky-rockets.

However, it is still better to address this problem by restricting 
individual expressions with max_distance.  Using depth of the search 
seems like too big a hammer.

Regards,

-- 
Maxim Kuvyrkov
CodeSourcery
maxim@codesourcery.com
(650) 331-3385 x724