[LLVMdev] Preferential treatment of labels in MI sched DAG construction

[Sergei Larin]

Excellent! Thanks. I'll put a patch up for review shortly.

Sergei

---
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by
The Linux Foundation


> -----Original Message-----
> From: Andrew Trick [mailto:atrick at apple.com]
> Sent: Monday, February 11, 2013 3:23 PM
> To: Sergei Larin
> Cc: llvmdev at cs.uiuc.edu
> Subject: Re: [LLVMdev] Preferential treatment of labels in MI sched DAG
> construction
> 
> 
> On Feb 11, 2013, at 1:03 PM, Sergei Larin <slarin at codeaurora.org>
> wrote:
> 
> > Hi Andy,
> >
> >  I have to resurrect an ancient question regarding scheduling
> boundaries.
> >
> > You might remember the reason for introduction of
> CanHandleTerminators
> > to ScheduleDAGInstrs. In short, Hexagon is currently uses DAG
> > construction method (buildSchedGraph) for several purposes, which
> > includes region formation for general VLIW packetization/bundling. As
> > such we need to handle pretty much all instructions and any
> > terminators, including labels (though I know it sounds strange).
> > Nevertheless, ScheduleDAGInstrs::buildSchedGraph
> > still has this hard assert in it:
> >
> > assert((!MI->isTerminator() || CanHandleTerminators) && !MI-
> >isLabel() &&
> >           "Cannot schedule terminators or labels!");
> >
> > ...and we have been OK till now by simply disabling it in our local
> > version of the code, but since we are now working towards upstreaming
> > all our code, this could no longer be ignored.
> >
> >  I guess my proposal is not to treat labels differently from any
> other
> > terminator - if a target wants to "schedule" labels - let it do so.
> It
> > actually works just fine for Hexagon... so if we can change this
> > assert to something like:
> >
> >
> > assert((!MI->isTerminator() || CanHandleTerminators) && "Cannot
> > schedule terminators or labels!");
> >
> >  It would equal label in rights with any other terminator. What do
> you
> > think?
> 
> Sure, as long as CanHandleTerminators is commented to that effect.
> 
> -Andy