[EMAIL PROTECTED] (Jack Howarth) writes: > Is there a wiki gcc page which accurately describes the > current status of IPA in gcc trunk?
Not to my knowledge. gcc trunk does support a type of Inter Procedural Analysis. It is always done, when optimizing, within a single source file. There is also the -combine option to do IPA across multiple files; it is documented, but it only works for the C frontend, and has some limitations. There is also an ongoing project to improve IPA across multiple files; this project is known as LTO (Link Time Optimization). > I have run across a > fortran benchmark which exhibits a huge improvement from > IPA when compiled on XL Fortran. I would like to attempt > to use the current IPA support in gcc trunk with gfortran > but it doesn't seem to be well documented. I was under the > impression that the gcc IPA would require collection of > profiling results which would then be used in a successive > compilation to implement the IPA optimizations. That is a procedure which I, at least, would probably not call IPA. That sounds more like what I would call Feedback Direction Optimization, FDO. gcc supports that, to a somewhat limited extended, independently of using IPA. For FDO, look in the documentation for -fprofile-generate and -fprofile-use. > ps Does each front-end have to be modified to use IPA or > will they automatically use it once it is added to gcc > trunk? Each front end will have to be modified to use IPA. No front end modifications are required to use FDO. Hope this helps. Ian
