Status of clang-llvm builds? Related to powerpc-spe.

[Hesham Almatary]

On Fri, 22 Jan 2021 at 21:30, <dufault at hda.com> wrote:
>
> Actually, replying to myself:
>
> I bet the context-switching code is broken for platforms that use the SPE via a Freescale library.  That's something I'll need to look at.
>
> > On Jan 22, 2021, at 14:26 , Peter Dufault <dufault at hda.com> wrote:
> >
> > Signed PGP part
> > The PowerPC Signal Processing Engine (powerpc-spe) is now gone from gcc and therefore from RTEMS (on the master branch).  It *appears* to be supported with Clang/LLVM on FreeBSD, apparently primarily to support some Amiga platforms (I think), I think it's supported beginning in FreeBSD 12.
> >
> > RTEMS has appropriately pulled out support for the SPE.  Since in the applications I use the SPE is used via libraries from Motorola/Freescale/... that may be OK, but having support for the architecture would "look good" to my clients.
> >
> > I'm not going to push for a project to switch to LLVM for the SPE targets, I don't have either the time or the money and I'm not going to ask my clients to fund it.  But I do want to know:
> >
> > - What's the status of Clang/LLVM and RTEMS?  Is it production-ready and production-used on certain (RISCV?) platforms?

I don't think so (at least for RISC-V). Currently, it relies on users
knowing how to build and teach LLVM about other externally-built libs
such as newlib and compiler-rt (libgcc). Also, I had to add an RTEMS
driver [1] to the backend and that's not upstream AFAIR.
We will need to teach RSB to build all of that (currently it has a
target for LLVM), newlib, compiler-rt and install a sysroot and a
config file that includes paths to the installed libs. Additionally,
to get C++ support, the relative libs will also need to be built
manually/separately.

[1] https://github.com/CTSRD-CHERI/llvm-project/blob/master/clang/lib/Driver/ToolChains/RTEMS.cpp

>
> > - Does anybody know anything the quality of the "powerpc-spe" support in Clang/LLVM?
> >
> > This is must an exploratory question.  I don't have a plan to work on this soon.
> >
> > Peter
> > -----------------
> > Peter Dufault
> > HD Associates, Inc.      Software and System Engineering
> >
> > This email is delivered through the public internet using protocols subject to interception and tampering.
> >
> >
> >
>
> Peter
> -----------------
> Peter Dufault
> HD Associates, Inc.      Software and System Engineering
>
> This email is delivered through the public internet using protocols subject to interception and tampering.
>
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