Hi Matt, No, I don't think anything extra is done in the native code generator when -O or -O2 are enabled. I believe that strictness information is used in the core stages only, eg to change let bindings (which allocate thunks) to case expressions (which don't) - but I haven't worked on the GHC core so I'm not that familiar with it. There's a plan to turn on the iterative register allocator that I wrote with -O2, but the STG to C-- translation needs to be improved before that will have much effect on performance. This is currently being completely overhauled by Norman Ramsey and co, so perhaps in 6.10. Cheers, Ben. Matthew Naylor wrote:
Hello GHC gurus,
specifying "-O" or "-O2" to GHC enables various optimisations to the frontend of the compiler, but I wonder does it turn on any optimistions to the backend/code-generator that are independent of the frontend?
I can imagine that knowledge such as strictness which is computed by frontend would enable optimisations in the backend, but I'm more interested in whether the backend would do anything independent (e.g. peephole optimistion, C compiler options) with "-O" but not without.
Thanks,
Matt. _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users