Re: Wrap calculation of PIC address into a single instruction

[Maxim Kuvyrkov <maxim at codesourcery dot com>]

On 6/24/10 1:22 AM, Steven Bosscher wrote:
> On Wed, Jun 23, 2010 at 11:19 PM, Maxim Kuvyrkov<maxim@codesourcery.com>  wrote:
> > This patch enables optimizations, particularly GCSE, handle calculation of
> > PIC addresses.  GCSE tracks only single instructions, so it can't handle
> > two-instruction calculation of PIC address.
> >
> > With this patch, calculations of PIC addresses are represented as single
> > instructions allowing GCSE eliminate all but the first address calculation
> > for global variables.
> >
> > Any comments?
>
> Yes. This is what we added GCSE's ability to eliminate redundancies
> from REG_EQUAL notes for. If your PIC addresses have a REG_EQUAL note,
> GCSE is (or should be) already able to eliminate redundant address
> calculations.

You know, it turns out GCSE can eliminate calculation of PIC addresses 
on ARM.  When I started working on improving code hoisting the example 
with PIC address wasn't fully optimized without this patch.

Now, apparently, one of the other GCSE improvements (VBEout computation, 
probably) fixed the underlying problem.

Richard, unless you think the patch may be valuable for some other 
reason, I'm dropping it.

Thanks,

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