I started to write the following message two days ago but I wished to send a .cloog which is not easy since I changed my laptop just before the trip I'm still on ! I need to finish installing all the tools... Here is the message, just a follow-up of Albert's one.
Ced. --- Hi Tobi, Sebastian gave you the right pointers, you should also have a look at examples in the CLooG test directory called tilingX.cloog. However to be honest I'm not fond of the second solution you suggested. The reason is the scattering is supposed to only drive the way the polyhedra are scanned. Adding new dimensions there is against this (well, I designed scattering this way -allowing inequalities- because I wished to do that, but I changed my mind and now I think it's dirty...). The right solution to me is acting both on the domain and in the scattering (in the end, something similar to your second solution). By the way we are incorporating directly inside CLooG the tiling scheme described there http://www.cs.colostate.edu/~ln/publications/pldi07.pdf (a student is working on this at this moment). --- On Mon, Jun 9, 2008 at 7:25 PM, Sebastian Pop <[EMAIL PROTECTED]> wrote: > Hi Tobi, > > Thanks for working on this. > > Solution 2 is the right one. > > On Mon, Jun 9, 2008 at 11:58 AM, Tobias Grosser > <[EMAIL PROTECTED]> wrote: >> 1. It is not very efficient. As we have many multiplications in the >> code. >> Will later gcc optimization passes convert these multiplications to >> additions? >> > > Yes, you should not worry about scalar optimizations at all. > >> 2. I could not find any documentation about scattering functions, that >> describe this way of using the scattering functions. >> > > I think that the best place to look at this is: > page 4 of http://www.lri.fr/~girbal/publi/ics05_facilitating.ps > > also have a look at the other reports from: > http://www.lri.fr/~girbal/site_wrapit/ > > Albert probably has some other pointers for reports that describe how > to do loop tiling. > >> Another graphite specific problem is, how we connect the real loop >> variables to the cloog variables. Before loop tiling this was easy. >> Loops of the same depth in the cloog output correspond to the loops of >> the same depth in the original gimple loop nest. But know we have to add >> some data structure, that connects the gimple loops, with the cloog >> loops. >> > > This was also the case before: we needed a map between the old > induction variable and the new ones. > > Sebastian Pop > -- > AMD - GNU Tools >
