The LLVM Developer Meeting was a great success. Many thanks to all participants, speakers and sponsors!
For anyone interested, the slides and videos are now available online:
Speakers: If you would like me to make any changes to your slides or abstract, please let me know off-list.
I have some code which relies on the floating point rounding mode to be set to round-to-negative-infinity. This means that there are some floating point optimizations which are legal with the default round-to-nearest mode but not with rounding to negative infinity. Does LLVM reorder or otherwise optimize floating point operations? I've looked at the options for "opt" but don't see anything to do with floating point so I assume no.
The intent is that it does optimizations as permitted by IEEE754 (i.e. negative zeroes, NaNs, and infinities should be handled correctly), and more aggressive ones with --enable-unsafe-fp-math (you don't want this). However we are not modelling the rounding mode yet, so it's likely this doesn't fully work as you want. Rounding mode handling is something we want to add, but so far there have always been more important things.