On Sat, May 7, 2011 at 5:46 AM, Richard Guenther <richard.guent...@gmail.com> wrote: > On Fri, May 6, 2011 at 7:57 PM, Xinliang David Li <davi...@google.com> wrote: >>>> I want propose a more general solution. >>>> >>>> 1) Generic Annotation Support for gcc IR -- it is used attach to >>>> application/optimization specific annotation to gimple statements and >>>> annotations can be passed around across passes. In gcc, I only see >>>> HISTOGRAM annotation for value profiling, which is not general enough >>>> 2) Support of CallInfo for each callsite. This is an annotation, but >>>> more standardized. The callinfo can be used to record information such >>>> as call attributes, call side effects, mod-ref information etc --- >>>> current gimple_call_flags can be folded into this Info structure. >>> >>> I don't like generic annotation facilities. What should passes to with >>> annotated stmts that are a) transformed, b) removed? See RTL notes >>> and all the interesting issues they cause. >> >> >> Then how do you store information that needs to be passed across >> optimization passes -- you can not possibly dump all of them into the >> core IR. In fact, anything that is derived from (via analysis) but not >> part of the core IR need to worry about update and maintenance. In >> current GIMPLE, we can find many such instances -- DU chains, Memory >> SSA, control flow information, as well as flags like visited, >> no_warning, PLF (?), etc. Have a unified way of representing them is a >> good thing so that 1) make the IR lean and mean; 2) avoid too many >> different side data structures. The important thing is to have a good >> verifier to catch insanity and inconsistency of the annotation after >> each pass. > > Well, as soon as you have a verifier it's no longer generic but _is_ > part of the "core IL". Similar to how EH info is part of the "core IL", > or alias info, or loop information.
The difference is that no-core IL can be thrown away anytime and be recomputed if needed. David > > Richard. >
