On Wednesday, 30 December 2015 at 21:56:46 UTC, Dan Olson wrote:
Dan Olson <go...@comcast.net> writes:
A little progress report. More to come later when I get
something pushed to github.
I bought a returned Apple Watch yesterday at discount for
$223.99 US and tried to see how much of D would work on it
using my iOS fork of LDC. There were a few bumps, like dealing
with embedded bitcode (a watchOS requirement). After 4-hours
of baby steps, little D programs with incremental druntime
support, I was able to download a huge watch app extension
with all druntime and phobos unittests and run most of them
alphabetically. Everything zipped along fine, only a std.math
error, then mysteriously a exit after running std.parallelism
test a long time. It was late for me so decided that was
enough progress.
This means all of druntime worked and probably most of phobos.
Played with this a little more and learned a bit about watchOS
memory. A little test that allocated memory in 5 MB chucks was
terminated at 30 MB data RAM. The combined unittests in phobos
suck up much more than that, std.uri itself uses over 50 MB.
By tailoring memory usage and running phobos unittests in
smaller block, they all work. The std.math failure was my own
coding error missing a version block for WatchOS.
In end, good news: druntime and phobos fully work on watchOS
with LLVM optimizations disabled. With optimzations on, there
are alignment problems. For example, compact unwind data
generated by LLVM isn't aligned but some of our eh unwinding
code casts these to uint. Not so good when the optimizer
selects instructions requiring special alignment. I'll track
these down gradually.
That sounds like this issue I ran into with ARM EH:
https://github.com/ldc-developers/ldc/issues/489#issuecomment-143560075
I was able to work around it by disabling the mentioned llvm
optimization pass:
https://gist.github.com/joakim-noah/1fb23fba1ba5b7e87e1a#file-android_tls-L42
https://gist.github.com/joakim-noah/63693ead3aa62216e1d9#file-ldc_android_arm-L3133
