RISC-V LLVM sync-up call 19th Dec 2019

For background on these calls, see
<http://lists.llvm.org/pipermail/llvm-dev/2019-September/135087.html>.

Reminder: the purpose is to co-ordinate between active contributors.
If you have support questions etc then it's best to post to llvm-dev.

We have a call each Thursday at 4pm GMT, via
<https://meet.google.com/ske-zcog-spp>.

NOTE: THERE WILL BE NO CALL NEXT WEEK DUE TO THE CHRISTMAS BREAK.
Today's call might be a quiet one too with various people already off
for the holidays.

I've created a shared calendar which may help in keeping track, which
is hopefully accessible at:
  * <https://calendar.google.com/calendar/b/1?cid=bG93cmlzYy5vcmdfMG41cGtlc2ZqY25wMGJoNWhwczFwMGJkODBAZ3JvdXAuY2FsZW5kYXIuZ29vZ2xlLmNvbQ>
  * <https://calendar.google.com/calendar/ical/lowrisc.org_0n5pkesfjcnp0bh5hps1p0bd80%40group.calendar.google.com/public/basic.ics>

Issues to discuss today include the following:
* Passing mabi in LTO https://reviews.llvm.org/D71387
* Machine outliner status - seems to be blocked by generic machine
outliner bug that shows up in the gcc torture suite
<https://reviews.llvm.org/D66210>
* uleb128 relocation
<https://github.com/riscv/riscv-elf-psabi-doc/pull/124>. Motivation
was size reduction, some discussion about correctness - if there
are cases where a uleb128 may increase after relaxation.
* Weak, undefined symbols in non-PIC code. https://reviews.llvm.org/D71100
which we mentioned last week spawned this psabi issue
<https://github.com/riscv/riscv-elf-psabi-doc/issues/126>
* ilp32e work ongoing <https://reviews.llvm.org/D70401>. See
<https://github.com/riscv/riscv-elf-psabi-doc/issues/125> which tries
to clarify the ABI for variadic function calls, specifically for
doubles on ilp32e.

Best,

Alex