[LLVMdev] Question about Value Range Propagation

[Duncan Sands]

Hi Andrey,

> On 21.02.2011 20:27, Douglas do Couto Teixeira wrote:
>> My work is not part of the LLVM mainline yet. But I would be happy to
>> contribute with the code of my range analysis implementation if it can help
>> you in something else.
> We were thinking of adding VRP to LLVM too, though we were mostly
> interested in Patterson's approach (i.e. not connected with SSI form).  It
> would be great if you can share the code nevertheless.

the big problem with Patterson's VRP is that it is expensive in terms of
compile time.  LLVM used to have some passes (ABCD, predsimplify) that did
this kind of thing, but they were removed essentially because their compile
time was too great for the goodness they brought.

Ciao, Duncan.