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Re: [PATCH GCC][1/6]Compute type mode and register class mapping


On Fri, May 25, 2018 at 10:45 AM Bin.Cheng <amker.cheng@gmail.com> wrote:

> On Thu, May 24, 2018 at 11:55 PM, Jeff Law <law@redhat.com> wrote:
> > On 05/18/2018 02:40 AM, Bin.Cheng wrote:
> >> On Fri, May 4, 2018 at 5:21 PM, Bin Cheng <Bin.Cheng@arm.com> wrote:
> >>> Hi,
> >>> This is the updated version patch set computing register pressure on
TREE SSA
> >>> and use that information to direct other loop optimizers (predcom
only for now).
> >>> This version of change is to follow Jeff's comment that we should
reuse existing
> >>> tree-ssa-live.c infrastructure for live range computation, rather
than inventing
> >>> another one.
> >>> Jeff had another concern about exposing ira.h and low-level register
stuff in
> >>> GIMPLE world.  Unfortunately I haven't got a clear solution to it.  I
found it's
> >>> a bit hard to relate type/type_mode with register class and with
available regs
> >>> without exposing the information, especially there are multiple
possible register
> >>> classes for vector types and it's not fixed.  I am open to any
suggestions here.
> >>>
> >>> This is the first patch estimating the map from type mode to register
class.
> >>> This one doesn't need update and it's the same as the original
version patch
> >>> at https://gcc.gnu.org/ml/gcc-patches/2017-05/msg01021.html
> >>>
> >>> Bootstrap and test on x86_64 and AArch64 ongoing.  Any comments?
> >> Hi,
> >> The original version of this patch was approved by Jeff
> >> @https://gcc.gnu.org/ml/gcc-patches/2017-06/msg01808.html
> >> Jeff, some new comment now or the old approval is still valid?
> >> Guess your major concern is about exporting ira.h to gimple world?
> > Yea, that was by far my biggest concern -- IRA is very much in the RTL
> > world and exposing it into the gimple world seems like a major layering
> > violation.
> >
> > So I have no inherent issues with this patch in isolation, but I may
> > have issues with subsequent patches if they introduce that kind of
> > layering violation.  So let's avoid installing until we have agreement
> > on the full set of patches.
> Sure, in the meantime, I will think again if there is way to avoid
> this shortage.

> The 3rd/4th patches are pure change to current live range and
> coalescing stuff which
> are irrelevant to this issue, I suppose it's okay to commit that two.

Yes.

> Thanks,
> bin
> >
> > jeff


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