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. Richard.
