[llvm-commits] [PATCH] Add Pattern ID Information

[Villmow, Micah]

> -----Original Message-----
> From: llvm-commits-bounces at cs.uiuc.edu [mailto:llvm-commits-
> bounces at cs.uiuc.edu] On Behalf Of Jakob Stoklund Olesen
> Sent: Friday, August 05, 2011 9:25 AM
> To: David A. Greene
> Cc: David A. Greene; llvm-commits at cs.uiuc.edu
> Subject: Re: [llvm-commits] [PATCH] Add Pattern ID Information
> 
> 
> On Aug 4, 2011, at 5:33 PM, David A. Greene wrote:
> 
> > Jakob Stoklund Olesen <stoklund at 2pi.dk> writes:
> >> Cleaning up isel debug output would be great. It is way too noisy.
> >
> > It's an admirable goal but way beyond the scope of this patch.
> >
> >>> It's really very difficult to map a piece of an asm file back to
> the
> >>> isel debug output related to it.
> >>
> >> That also applies to DAG combine, scheduling, and even InstCombine.
> >
> > Yes it does.  In other compiler projects I have emitted similar asm
> > comments to track various transformations.  But that's not on the
> table
> > here.
> 
> I could perhaps see the utility of a general mechanism for annotating
> machine instructions, but as you say, this patch doesn't bring us any
> closer to that. It is one more ad-hoc thing on top of the existing
> AsmPrinterFlags.
> 
> We added AsmPrinterFlags almost two years ago. In that time, nobody has
> defined more flags, and the existing ReloadReuse flag is only written
> by VirtRegRewriter.cpp which isn't even in the default pipeline any
> more.
> 
[Villmow, Micah] This is extremely useful for our internal backend. I use it
to encode per instruction information that does not fit into the 'flags' 
field without having to extend the MachineInstr class. 

> I simply don't think this is useful to anyone else.
> 
> /jakob
> 
> 
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