[lldb-dev] [RFC] Contributing platform support for Linux on SystemZ

Pavel Labath via lldb-dev lldb-dev at lists.llvm.org
Mon Apr 11 08:29:02 PDT 2016

Hello Ulrich,

It's exciting to see support for new platforms being added to LLDB.
I've had a brief glance at the patch set and I was surprised at how
few changes you had actually needed to make to lldb core to support
this. The patches look good at a first glance, but they will need to
be reviewed by respective code owners.

Going forward, the best way to handle this would be to create a
phabricator account and submit the patches there. This will make the
review much easier. For reviewers, you can use the CODE_OWNERS.txt
file (or just git history). If you don't know the right person, just
pick Greg Clayton for general stuff and me or Tamas Berghammer for
Linux-specific code, and we will route it further if needed.

Also, please run clang-format on your patches before submission. Let
me know if you need any help setting that up.

> This should provide complete support for debugging the base SystemZ
> platform. Not yet supported are optional features like transaction support
> (zEC12) or SIMD vector support (z13). Note that there is no instruction
> emulation, since our ABI requires that all code provides correct DWARF CFI
> in .eh_frame to support unwinding.

Is the CFI info correct at all PC locations, or only at call sites
(synchronous vs. asynchronous exceptions). If it's the latter, you may
still need to do some instruction emulation to "augment" the CFI info
for it to be usable at non-call-sites. However, that's definitely not
a blocker now...

> Looking forward to working with you on getting SystemZ support upstream! I'd
> also be happy to take on ongoing maintenance (setting up a build bot, fixing
> issues as they come up, etc ...).

Setting up a buildbot is definitely recommended and it will make
further significantly easier.


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