Douglas Katzman <email address hidden> writes:

> I don't think we've blessed the ppc64 into official existence yet. The
> downloadable binaries don't have it, and the status page says that
> it's in progress.

Oh yeah, I hadn't checked that page in a while.

> We need to establish a matrix of known good configurations: what
> combinations of endian-ness, word size, and ABI versions are expected
> to work.

Makes sense.  I can offer some opinions about the matrix specifically
for systems running the Linux kernel and the GNU C Library.

For 32-bit word size, I think the 32-bit PowerPC SBCL support is fine
as-is.  As far as I know, no little endian ppc32 systems ever existed,
and there were no major ABI versions to choose from.  (It might make
sense to upload current ppc binaries to the website, but I don't know
the criteria or procedures for doing so.)

For 64-bit PowerPC, this is the table I'm thinking of:

| Configuration  | Existed | Distro       | SBCL Support |
|----------------+---------+--------------+--------------|
| ppc64-le-abiv1 | Never   | ;;           | ;;           |
| ppc64-be-abiv1 | YES     | Debian/glibc | YES¹         |
| ppc64-le-abiv2 | YES     | Debian/glibc | YES          |
| ppc64-be-abiv2 | YES     | Void/glibc²  | DESIRED      |

1. With the patches in bug 1900258 and bug 1900343, ppc test results [a]
   and ppc64 test results [b] seem pretty similar, so I optimistically
   put "YES" here instead of "DESIRED".

2. glibc has support for big-endian ABIv2 which Void-ppc enables.
   However, glibc does not officially support ABIv2 for big-endian
   because it is not backward compatible with ABIv1, which already
   existed for big-endian ppc64 before ABIv2 came out.  From what I've
   seen on some IRC channels though, there's desire to use ABIv2 for
   big-endian, with Void-ppc being one example.  I think SBCL should
   strive to work for that configuration.

SBCL currently uses big-endian and little-endian feature expressions
where it would probably be clearer to define abiv1 and abiv2 features
(some of the comments allude to this).  Practically though,
little-endian implies ABIv2 and big-endian implies ABIv1.  It would
probably be overkill, for instance, to make a new column on the status
page for PPC64-ABIv2.

> As far as I know, more tests pass for ppc32 big-endian than pass for
> ppc64 big-endian, so that situation would need to be corrected.
> (Lacking any historical data as to what passed on ppc 32-bit, I don't
> even know whether that's getting better or worse, but I have a feeling
> it's doing a little of both, as is ppc64)

I happened to run the ppc32 test suite on a Debian 10 virtual machine to
regression-test my second patch for bug 1900258; I attached the results
[a] of a test run on commit 514934074c1afa1d50a50f93091ffe8e0a0075b2
prior to applying my patches.  I also attached ppc64 results [b] for
comparison.

> I have heard anecdotal evidence that the ppc64 has some suboptimal
> compilation that may be considered a regression relative to ppc32; so
> if somebody does have 32-bit libraries installed, they may well prefer
> to build the 32-bit code.

Hmm, OK, it'd be nice to have bugs filed for such regressions.

> That said, if the build machine fits into one of the known good configs
> for 64-bit, and can be auto-detected as such, and does NOT have 32-bit
> (like little-endian which never had a 32-bit ABI, or 64-bit which
> installed as yours lacks the requisite headers and libraries) then I'd
> say sure, switch it.

OK, yeah, that could work.  I think I'll live with "--arch=ppc64" for
now (rather than submitting an extra configuration patch), in the hope
that PPC64 is close to being made official.

Inline attachments:

a. ppc "sh ./run-tests.sh" results on
   514934074c1afa1d50a50f93091ffe8e0a0075b2:

Finished running tests.
Status:
 Expected failure:   array.pure.lisp / CHECK-BOUND-SIGNED-BOUND-NOTES
 Expected failure:   compiler-2.pure.lisp / (MAP-ALLOCATED-OBJECTS NO-CONSING)
 Failure:            compiler-2.pure.lisp / MODULAR-ARITH-TYPE-DERIVERS
 Expected failure:   compiler-2.pure.lisp / DEDUPLICATED-FDEFNS
 Expected failure:   compiler.pure.lisp / (ODDP BIGNUM NO-CONSING)
 Expected failure:   compiler.pure.lisp / (LOGTEST BIGNUM NO-CONSING)
 Expected failure:   hash.pure.lisp / SXHASH-ON-DISPLACED-STRING
 Skipped (broken):   interface.pure.lisp / RESTART-BOGUS-ARG-TO-VALUES-LIST-ERROR
 Expected failure:   compiler.impure.lisp / BUG-308921
 Expected failure:   compiler.impure.lisp / FTYPE-RETURN-TYPE-CONFLICT
 Expected failure:   debug.impure.lisp / PROPERLY-TAGGED-P-INTERNAL
 Expected failure:   dynamic-extent.impure.lisp / DX-COMPILER-NOTES
 Expected failure:   fopcompiler.impure.lisp / FOPCOMPILER-DEPRECATED-VAR-WARNING
 Expected failure:   full-eval.impure.lisp / INLINE-FUN-CAPTURES-DECL
 Failure:            gc.impure.lisp / (SEARCH-ROOTS SIMPLE-FUN)
 Expected failure:   packages.impure.lisp / USE-PACKAGE-CONFLICT-SET
 Expected failure:   packages.impure.lisp / IMPORT-SINGLE-CONFLICT
 Failure:            run-program.impure.lisp / IS-/BIN/ED-INSTALLED?
 Failure:            run-program.impure.lisp / (RUN-PROGRAM /BIN/ED)
 Failure:            run-program.impure.lisp / (RUN-PROGRAM INHERIT-STDIN)
 Skipped (broken):   timer.impure.lisp / (TIMER PARALLEL-UNSCHEDULE)
 Expected failure:   walk.impure.lisp / (WALK MULTIPLE-VALUE-BIND)
 Expected failure:   walk.impure.lisp / (WALK MULTIPLE-VALUE-BIND SPECIAL)
(105 tests skipped for this combination of platform and features)
test failed, expected 104 return code, got 1

b. ppc64 "sh ./run-tests.sh" results on
   11be25c925032594980697273de1c8d505a89712 plus patches from bug
   1900258 and bug 1900343:

Finished running tests.
Status:
 Expected failure:   array.pure.lisp / CHECK-BOUND-SIGNED-BOUND-NOTES
 Failure:            compiler-2.pure.lisp / PACK-VARINTS-AS-BIGNUM
 Skipped (broken):   compiler-2.pure.lisp / (MV-CALL MORE-ARG-UNUSED)
 Failure:            compiler-2.pure.lisp / MODULAR-ARITH-TYPE-DERIVERS
 Expected failure:   hash.pure.lisp / SXHASH-ON-DISPLACED-STRING
 Skipped (broken):   interface.pure.lisp / RESTART-BOGUS-ARG-TO-VALUES-LIST-ERROR
 Unexpected success: threads.pure.lisp / (WAIT-ON-SEMAPHORE SEMAPHORE-NOTIFICATION LP-1038034)
 Expected failure:   compiler.impure.lisp / BUG-308921
 Expected failure:   compiler.impure.lisp / FTYPE-RETURN-TYPE-CONFLICT
 Expected failure:   debug.impure.lisp / PROPERLY-TAGGED-P-INTERNAL
 Expected failure:   dynamic-extent.impure.lisp / DX-COMPILER-NOTES
 Expected failure:   fopcompiler.impure.lisp / FOPCOMPILER-DEPRECATED-VAR-WARNING
 Expected failure:   full-eval.impure.lisp / INLINE-FUN-CAPTURES-DECL
 Skipped (broken):   gethash-concurrency.impure.lisp / (HASH-TABLE UNSYNCHRONIZED)
 Failure:            make-thread.impure.lisp / EXPECTED-GC-ROOTS
 Expected failure:   packages.impure.lisp / USE-PACKAGE-CONFLICT-SET
 Expected failure:   packages.impure.lisp / IMPORT-SINGLE-CONFLICT
 Failure:            run-program.impure.lisp / IS-/BIN/ED-INSTALLED?
 Failure:            run-program.impure.lisp / (RUN-PROGRAM /BIN/ED)
 Failure:            run-program.impure.lisp / (RUN-PROGRAM INHERIT-STDIN)
 Skipped (broken):   threads.impure.lisp / BACKTRACE
 Expected failure:   walk.impure.lisp / (WALK MULTIPLE-VALUE-BIND)
 Expected failure:   walk.impure.lisp / (WALK MULTIPLE-VALUE-BIND SPECIAL)
 Invalid exit status: relocation.test.sh
 (55 tests skipped for this combination of platform and features)
test failed, expected 104 return code, got 1