On Thu, Mar 5, 2009 at 3:09 PM, Seema Ravandale <ravandal...@gmail.com> wrote: > Hello Sir, > > On Wed, Mar 4, 2009 at 7:44 PM, Manuel López-Ibáñez > <lopeziba...@gmail.com> wrote: >> I am no expert in this area, so please consider that I may be >> misunderstanding something. >> >> This seems a data flow analyzer for GIMPLE. So the analysis results >> can be used by the FE, am I wrong? >> > > ( I am assuming by FE you mean, front end and VRP is value range propagation) > > GIMPLE is a stage after front end perticularely after AST, type > checking etc is done. > So I can't visualize how it can be used in FE. > As far as i know, Data flow analysis is used for the purpose of, > 1. Optimizations > 2. Producing dignostic information about source code. > >> Could it be used to propagate constant values? What about VRP in the FE? >> > > We have implemented bit vector analysis framework only. Constant > propagation is not implemented yet, so no VRP :) > >> What is the overhead involved? > > We are using existing IR, existing APIs for accessing GIMPLE data structure. > Only new pass to perform DFA has been added to the GCC pass structure. > The space overhead is interms of storage of data flow values using sbitmap. > >> >> I ask because I know that Clang performs data flow analysis in the FE >> to provide better warnings, and Chris Lattner said that the overhead >> of doing this was very low. >> > > The beauty of GDFA code lies within, the specifications provided for GDFA. > One does not have to implement local analysis in order to incorporate > new data flow analysis. (for time being, bit vector analysis)
Does it do data-flow analysis on memory or only on SSA_NAMEs? If it does data-flow analysis on memory, what is the granularity in case of structures/arrays and subsetting? Richard. > - Seema > - Show quoted text - >> Cheers, >> >> Manuel. >> >> 2009/3/4 Seema Ravandale <ravandal...@gmail.com>: >>> Announcement: gdfa - Generic data flow analyzer for GCC. >>> Developed by: GCC resource center, IITB >>> >>> Patch and the Documentation can be found at the below link, >>> >>> http://www.cse.iitb.ac.in/grc/gdfa.html >>> >>> >>> Ms. Seema S. Ravandale >>> Project Engg, >>> GCC Resource Center >>> Department of Computer Science & Engg. >>> IIT Bombay, Powai, Mumbai 400 076, India. >>> email - se...@cse.iitb.ac.in >>> >> >
