For those who have been following my adventure in the world of IRA, or
just
want to take advantage of some of the time I've spent on this, here's a
detailed recap of my exploits and my current status (which I'm very
happy
with):
I initially thought IRA was calculating costs wrongly for our
archite
Jeff Law wrote:
> >
> > I had an epiphany this morning and came up with an idea to achieve
> the
> > lookahead I thought I needed, thereby making the costs created by '?'
> a
> > lot more concrete and reliable.
> >
> > Firstly, I have altered the alt_cost adjustment (for '?') in ira-
> costs.c,
> >
On 12/02/09 13:29, Ian Bolton wrote:
I had an epiphany this morning and came up with an idea to achieve the
lookahead I thought I needed, thereby making the costs created by '?' a
lot more concrete and reliable.
Firstly, I have altered the alt_cost adjustment (for '?') in ira-costs.c,
so that i
Jeff Law wrote:
> Ian Bolton wrote:
> > Initial results showed that IRA was moving input arguments out of
> their
> > BOTTOM_REGS (e.g. $c1) into TOP_CREGS to do work on them, since it
> > thought TOP_CREGS were less costly to use, despite the cost of the
> move
> > instruction to get the input ar
On 11/19/09 08:40, Ian Bolton wrote:
Jeff Law wrote:
On 11/16/09 10:33, Ian Bolton wrote:
The question is: how to fix this? I have initially put the
REG_ALLOC_ORDER
back to how it was and changed the operand constraints in our MD
file,
so each of the "
Jeff Law wrote:
> On 11/16/09 10:33, Ian Bolton wrote:
> > The question is: how to fix this? I have initially put the
> REG_ALLOC_ORDER
> > back to how it was and changed the operand constraints in our MD
> file,
> > so each of the "apathetic" instructions, will either take a 't'
> (TOP_CREG)
> >
Ian Bolton wrote:
> Ian Bolton wrote:
> > Vladimir Makarov wrote:
> > > Ian Bolton wrote:
> > > > Yesterday, I wrote:
> > > >
> > > >> BTW, today I have achieved some good results with existing IRA
> by
> > > doing
> > > >> the following:
> > > >>
> > > >> 1) Changed the REG_ALLOC_ORDER so that TOP
Ian Bolton wrote:
> Vladimir Makarov wrote:
> > Ian Bolton wrote:
> > > Yesterday, I wrote:
> > >
> > >> BTW, today I have achieved some good results with existing IRA by
> > doing
> > >> the following:
> > >>
> > >> 1) Changed the REG_ALLOC_ORDER so that TOP_CREGS are given out
> > before
> > >> B
Vladimir Makarov wrote:
> Ian Bolton wrote:
> > Yesterday, I wrote:
> >
> >> BTW, today I have achieved some good results with existing IRA by
> doing
> >> the following:
> >>
> >> 1) Changed the REG_ALLOC_ORDER so that TOP_CREGS are given out
> before
> >> BOTTOM_REGS. My previous hacked version
Ian Bolton wrote:
Yesterday, I wrote:
BTW, today I have achieved some good results with existing IRA by doing
the following:
1) Changed the REG_ALLOC_ORDER so that TOP_CREGS are given out before
BOTTOM_REGS. My previous hacked version worked by increasing the
priority of those that wanted B
On 11/11/09 08:18, Ian Bolton wrote:
Good news! I have been able to remove my "total_costs" hack
above by instead commenting out the following line from ira_build()
in ira-build.c:
remove_unnecessary_regions (false);
Which is probably an indication of a problem elsewhere. However, it's
Yesterday, I wrote:
> BTW, today I have achieved some good results with existing IRA by doing
> the following:
>
> 1) Changed the REG_ALLOC_ORDER so that TOP_CREGS are given out before
> BOTTOM_REGS. My previous hacked version worked by increasing the
> priority of those that wanted BOTTOM_REGS,
[ Per Ian's request I'm forwarding some discussion we had on IRA to the
list. ]
On 11/04/09 12:24, Ian Bolton wrote:
Hi Jeff and Vladimir,
(I wasn't sure whether to CC the mailing list. Your guidance on this
would be appreciated, since I am very new to the GNU community.)
Your choice. There'
> On 11/06/09 05:53, Dave Hudson wrote:
> > the most
> > critical thing was to ensure that REGNO_REG_CLASS was returning a
> > minimal class correctly.
> I believe that's been documented as the right thing to do for about 15
> years :-) So, yes, you definitely want REGNO_REG_CLASS to return the
On 11/06/09 05:53, Dave Hudson wrote:
the most
critical thing was to ensure that REGNO_REG_CLASS was returning a
minimal class correctly.
I believe that's been documented as the right thing to do for about 15
years :-) So, yes, you definitely want REGNO_REG_CLASS to return the
smallest clas
On Mon, 2009-11-09 at 14:13 +, Ian Bolton wrote:
> Dave Hudson wrote:
> > I've been working on gcc for an ISA (Ubicom32) that seems to have some
> > similarities to the problem you're seeing (we have some regs that can
> > be
> > used for many things but not all) and was seeing a ton a pointles
Dave Hudson wrote:
> On Thu, 2009-11-05 at 18:05 +, Ian Bolton wrote:
> > I think I may have made a breakthrough!
> >
> > As mentioned above, IRA is correctly increasing the cost for TOP_REGS
> > when an allocno in region 1 is being used in one of our special
> > instructions that needs BOTTOM_
On 11/04/09 10:14, Vladimir Makarov wrote:
I am agree with Jeff. It is hard to understand what you are doing
without the architecture knowledge and some macro values in your port
(IRA_COVER_CLASSES, MEMORY_MOVE_COST, and REGISTER_MOVE_COST).
I'd also add that besides right macro value defin
On 11/04/09 10:52, Ian Bolton wrote:
Hi Jeff,
From an empirical perspective, the value of your patch is hard to
determine at this stage - one benchmark improved about 0.5% but others
have marginally regressed.
It's a hack, no doubt about it. Your results are about what I expected,
a few t
re an ETA on when reload will be gone away? ;-)
Best regards,
Ian
> -Original Message-
> From: Jeff Law [mailto:l...@redhat.com]
> Sent: 22 October 2009 23:05
> To: Ian Bolton
> Cc: Vladimir Makarov; gcc@gcc.gnu.org
> Subject: Re: Understanding IRA
>
> On 10/
Jeff Law wrote:
On 11/03/09 09:29, Ian Bolton wrote:
Hi again, Vladimir,
I am pleased to report some performance improvements after altering
ira-costs.c. A key benchmark for us has improved by 5%.
Specifically, in record_reg_classes(), after the alt_cost has been
calculated and it will be app
On 11/03/09 09:29, Ian Bolton wrote:
Hi again, Vladimir,
I am pleased to report some performance improvements after altering
ira-costs.c. A key benchmark for us has improved by 5%.
Specifically, in record_reg_classes(), after the alt_cost has been
calculated and it will be applied to pp->mem_c
Hi again, Vladimir,
I am pleased to report some performance improvements after altering
ira-costs.c. A key benchmark for us has improved by 5%.
Specifically, in record_reg_classes(), after the alt_cost has been
calculated and it will be applied to pp->mem_cost and pp->cost[k], I
check whether th
On 10/19/09 12:30, Ian Bolton wrote:
Hi Jeff and Vladimir.
Jeff: I'd be interested in trying the patch if you can send it my way.
It's nothing special.
/* Return nonzero if REGNO is a particularly bad choice for reloading X. */
static int
ira_bad_reload_regno_1 (int regno, rtx x)
{
int
Ian Bolton wrote:
Hi Jeff and Vladimir.
Jeff: I'd be interested in trying the patch if you can send it my way.
Vladimir: Today I have seen reasonable improvements on
progressively-trimmed-down versions of a *single* test case by applying
some cost adjustments in the case when an operand wants o
t: Re: Understanding IRA
On 10/16/09 08:53, Vladimir Makarov wrote:
>
> The biggest problem of GCC RA is still reload pass. It frequently
> changes decisions of IRA not in a good way.
Agreed. Not only may reload make a bad choice, it's horribly
unpredictable. Trivial changes often lead to dr
On 10/16/09 08:53, Vladimir Makarov wrote:
The biggest problem of GCC RA is still reload pass. It frequently
changes decisions of IRA not in a good way.
Agreed. Not only may reload make a bad choice, it's horribly
unpredictable. Trivial changes often lead to drastically different
reloading
Ian Bolton wrote:
I hope you could also make some suggestions as to how I might
help IRA work well with our instructions that can only use a subset
of the register bank.
I forgot to write: thanks, it would be interesting for me to see your
suggestions :)
Ian Bolton wrote:
Hi Vladimir,
I have just begun working for Icera Inc, on a private port of GCC,
and my first task has been to investigate the performance impact of
using the Chaitin-Briggs algorithm of IRA vs the priority algorithm
that we currently have enabled in our production compiler (due
29 matches
Mail list logo
