[LLVMdev] Create superblock in LLVM IR

[Alexander Potapenko]

Last time I asked here about superblocks (which we were using in the
first version of ThreadSanitizer instrumentation) Tobias Grosser has
suggested to use RegionInfo:

   did you have a look at the RegionInfo pass? It currently detects some
   kind of refinded SESE regions. I use them in Polly and as far as I know
   the Intel OpenCL SDK also uses them in some way. It is not SEME, but it
   may either fit your needs or we may think about extending it.

   If you want to give it a try you can use:

   opt -view-regions-only file.ll

   It would be great if we could have just a single RegionInfo analysis
   that can then be used by other passes to detect and/or generate the kind
   of regions they need.