Thumb2 code size improvements

[Yao Qi]

Loïc Minier wrote:
> On Fri, Sep 03, 2010, Yao Qi wrote:
>> We are looking for some possible improvements and optimizations on
>> thumb2 code size.  Currently, I am running some benchmarks with
>> compilation flag "-Os -march=armv7-a -mthumb", and hope to find some
>> thing interesting that we can improve.  Beside that, do you have some
>> ideas on this topic? or do you have some observations on thumb2 code
>> that we may probably improve the size?
> 
>  One of the largest self-contained piece of code which we'll find on all
>  systems which Linaro targets is ... the kernel.  It's not always
>  trivial to build it in Thumb mode, but it would seem like a good test
>  case nevertheless.  At least if it builds, looking at the resulting
>  size would be a good test, even if it doesn't boot  :-)

Yeah, kernel is a good test case here, and it is not so hard to compile
kernel as thumb2.  Linux kernel can be a good evidence if we optimize
its size when this work item is done. :)

However, we'd like to probe any possible improvements on code size that
we can do.  This part is hard, and I have few ideas so far.  Thoughts?