[LLVMdev] Proposal for ""llvm.mem.vectorize.safelen"

[Robison, Arch]

> We must do this directly in the frontend. Relying on another 
> pass run early would be bad because it would introduce a hard-to-enforce
> contract affecting correctness.

Instead of a pass, the marking could be a utility routine that client
front ends can run?  Or maybe it's not a big deal.  I guess I'll find out
when I modify the Julia front-end :-)

> Also, we should probably allow for missing access numbers, so long 
> as everything is in order (because the optimizer might eliminate some of them). 
> Some memory-access instructions might also have more than one access number 
> (after GVN, vectorization, etc.), and we should allow for that.

I concur that holes and duplicates should be allowed.

- Arch Robison
  Intel Corporation