Re: [PATCH, sched] Cleanup and improve multipass_dfa_lookahead_guard

[Jeff Law <law at redhat dot com>]

On 05/19/14 22:27, Maxim Kuvyrkov wrote:
> Hi,
>
> This patch cleans up haifa-sched.c:choose_ready() function while
> allow more powerful customization by backends at the same time.
>
> The primary change is that
> targetm.sched.first_cycle_multipass_dfa_lookahead_guard hook is
> converted from returning a boolean OK/Nada value to returning an
> action to be applied to a given instruction in the ready list.
>
> If return value is N == 0, then insn is OK (previous corresponding
> return value was 1). If return value is N  < 0, then insn should not
> be considered for scheduling for -N cycles (I'm going to use this for
> ARM scheduling in an upcoming patch). If return value is N  > 0, then
> insn can still be issued on the current cycle, just not immediately
> now (previous corresponding return value was 0).
>
> Changes to ia64 and rs6000 are mostly mechanical to update hook
> return values, but port maintainers may wish to review those.
>
> Tested on x86_64-linux-gnu, arm-linux-gnueabihf, and by building
> ia64-linux-gnu cc1.  Changes to PowerPC were seriously eyeballed.  If
> maintainers so to wish, I will carry out any additional testing.
This looks OK to me.

I think it's safe to work from the assumption that the hook will never 
return INT_MIN :-)

jeff