On 09/13/2010 07:00 PM, Ian Romanick wrote:
Module: Mesa Branch: master Commit: 2cdbced10d98214616bcc5f960b21185c433d23b URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=2cdbced10d98214616bcc5f960b21185c433d23bAuthor: Luca Barbieri<l...@luca-barbieri.com> Date: Tue Sep 7 17:03:43 2010 +0200 loop_unroll: unroll loops with (lowered) breaks If the loop ends with an if with one break or in a single break unroll it. Loops that end with a continue will have that continue removed by the redundant jump optimizer. Likewise loops that end with an if-statement with a break at the end of both branches will have the break pulled out after the if-statement. Loops of the form for (...) { do_something1(); if (cond) { do_something2(); break; } else { do_something3(); } } will be unrolled as do_something1(); if (cond) { do_something2(); } else { do_something3(); do_something1(); if (cond) { do_something2(); } else { do_something3(); /* Repeat inserting iterations here.*/ } } ir_lower_jumps can guarantee that all loops are put in this form and thus all loops are now potentially unrollable if an upper bound on the number of iterations can be found.
It would be nice if the example above was in a comment in the loop_unroll.cpp file. Similarly, it would be nice if there were comments/examples showing the transformation done by each of the (non-trivial) lowering passes. I think that'd help people better understand what's going on.
-Brian _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
