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Re: Obsolete powerpc*-*-*spe*
On Tue, Feb 14, 2017 at 03:26:09PM +0100, Sebastian Huber wrote:
> >>>I propose to mark powerpc*-*-*spe* as obsolete in GCC 7. This includes
> >>>the spe.h installed header file, all the __builtin_spe* intrinsics, the
> >>>-mfloat-gprs= command-line option, and the support for the SPE ABIs.
> >>>No one has properly tested these targets in a long time (the latest
> >>>testresults I could find are from July 2015, >1000 failures), and the
> >>>SPE support makes a lot of code much more complex.
> >>>Any objections to this obsoletion? GCC 7 will then be the last release
> >>>with support for SPE (it will need --enable-obsolete to build these
> >>>targets), and we will delete the SPE support during GCC 8 development.
> >>the SPE unit is still used in the embedded PowerPC processors from
> >>Freescale/NXP/Qualcomm, for example QorIQ P1020. These products are not
> >>obsolete or even not recommended for new designs. These chips have a
> >>long product life-cycle.
Yes. SPE is part of some e500 and some e200 CPUs I think (but only
some, in both cases).
> >It is also used in many PPC based microcontrollers, which are used in
> >the automotive industry and other places where you need highly reliable
> >and robust but powerful microcontrollers. However, gcc support for
> >these has traditionally been poor - there is little support for the
> >variety of cores and configurations available from Freescale/NXP. I
> >believe there is a chicken-and-egg situation here - few people use gcc
> >with these devices because there is poorer device support compared to
> >Freescale CodeWarrior or Green Hills, and there is little incentive for
> >gcc developers (such as the CodeSourcery or IBM PPC folks) to support
> >devices in gcc if no one uses that combination.
> Yes, we use GCC also one these chips, however, due to the lack of VLE
> support the situation is even worse. Looks like support for the non-IBM
> PowerPC is dead in GCC. I can understand this pretty well.
It's not true though; we still support all those cores, just not the
VLE extension (we never have), and I propose GCC 7 will drop the SPE
extension as well -- not all other support we have for those cores.
They will have to use soft float, alas.
We also still support all non-IBM non-FSL cores.
> With the Qualcomm takeover of Freescale/NXP I guess the PowerPC has no
> future in this area and they will move to ARM for the processor cores.
That is my understanding as well, yes.
> >>Its a pity that Freescale/NXP/Qualcomm stopped to support GCC
> >>development and IBM is burdened to take care of this. I can understand
> >>your reasoning, however, its not true that there are no users of the SPE
(I never said there are no users, I'm well aware). The burden is not
just IBM's, also all other GCC developers and users.
> >I think what would be needed would be for Freescale/NXP/Qualcomm to put
> >some money and effort in here, with the aim of making gcc their standard
> >compiler for these targets (as they have done for ARM, replacing the old
> >CodeWarrior compiler).
> >Failing that, it is of course better to have no SPE support than broken
> >SPE support, especially if it makes development harder for other devices.
> Yes, in case Qualcomm shows no interest to support their PowerPC stuff
> in GCC its quite understandable to remove the support for it eventually.
> IBM already did a great job in keeping it up and running for a long time.
That is the unfortunate reality.