On Wed, Jan 8, 2014 at 8:27 AM, Felix Yang <fei.yang0...@gmail.com> wrote: > Hi Sterling, > > This patch implements zero-overhead looping for xtensa backend using > hw-doloop facility. > If OK for trunk, please apply it for me. Thanks.
Hi Felix, I last worked on zero-overhead loops for Xtensa in the gcc 4.3 timeframe, but when I did, I ran into several problems related to later optimizations rearranging the code which I didn't have time to address. I'm sure much of that experience is completely stale now, but I would appreciate a detail of the testing you have done with this patch (in particular, a description of the different xtensa configurations you tested it against, especially the ones with and without loop instructions) before I approve it. Please be sure the assembler can relax the loops it generates as well. I don't see any particular problem, but there are many, many gotchas when dealing with xtensa loop instructions. It also appears that Tensilica has stopped posting test results for Xtensa, which makes it difficult to evaluate the quality of this patch. Thanks, Sterling
