[LLVMdev] Question regarding the alias analysis chaining behaviour

[Kenneth Uildriks]

On Wed, Nov 24, 2010 at 2:50 PM, Nick Lewycky <nicholas at mxc.ca> wrote:

> The AA that you specify will be created when you specify it and live
> until that pass is invalidated (not explicitly preserved by a pass that
> runs). The next time a pass requires AA, the pass manager will create
> the default AA (BasicAA) and not the one you put on the command line.
>

I thought analysis passes just rebuilt their state after they got
invalidated.  Shouldn't that happen with an AA pass as well?  Or is AA
special?