[LLVMdev] Proposal for Poison Semantics

[John Regehr]

> I am actively working towards removing poison altogether.  I think a more accurate model of LLVM's wrapping
> flags is not poison but instead something akin to the fast-math flags on floating point instructions.

Looking forward to seeing it. One of my students has a hacked lli that 
tracks poison, it's a nice playground for trying to understand the 
interaction of poison with programs and with LLVM passes. We can hopefully 
implement your new semantics as an option in order to better understand 
it. In one way, the hacked lli is not as good as Alive (it only reasons 
about one execution at a time) but on the other hand it tells us what 
happens for real codes which Alive does not.

John