<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW - Add FP64 support to the i965 shader backends" href="https://bugs.freedesktop.org/show_bug.cgi?id=92760#c91">Comment # 91</a> on <a class="bz_bug_link bz_status_NEW " title="NEW - Add FP64 support to the i965 shader backends" href="https://bugs.freedesktop.org/show_bug.cgi?id=92760">bug 92760</a> from <a class="email" href="mailto:jasuarez@igalia.com" title="Juan A. Suarez <jasuarez@igalia.com>"> Juan A. Suarez</a> <pre>(In reply to Francisco Jerez from <a href="show_bug.cgi?id=92760#c89">comment #89</a>) > (In reply to Juan A. Suarez from <a href="show_bug.cgi?id=92760#c88">comment #88</a>) > >[..] > > Related with this topic, current liveness analysis code (and also DCE > > optimization) just ignore the types when dealing with the swizzles. This > > works fine, except when reading/writing a channel from DF type (64-bit > > channel), and write/read it later as F (32-bit channel). > > > > For instance, for this piece is code: > > > > mov(8) vgrf3.0.x:UD[1], 2576980378U[1] NoMask > > mov(8) vgrf3.0.y:UD[1], 1071225241U[1] NoMask > > mov(8) vgrf3.1.x:UD[1], 2576980378U[1] NoMask > > mov(8) vgrf3.1.y:UD[1], 1071225241U[1] NoMask > > mov(8) vgrf2.0.xy:DF[2], vgrf3.0.xxxx:DF[2] > > > > Our liveness analysis just decide vgrf3.0.y channel is not live anymore and > > thus DCE removes it. That is because in latest instruction it doesn't > > realize vgrf3.0.x:DF is reading both vgrf3.0.x:F and vgrf3.0.y:F. > > > > In order to avoid introducing too many changes in our current code, I've > > added a pair of commits[1][2] that basically try to check if a 32-bit > > channels was previously read as 64-bit (and the other way around). This > > seems to fix above problem. > > Seems very sketchy. You need to fix the current dataflow analysis logic to > flip/check as many bits per channel from the live, use or def bitsets as the > corresponding source or destination datatype takes, just like the FS back-end > handles multi-GRF defs and uses. > Thanks for the feedback! I threw away the changes done, and re-did it following your suggestion. Now, it flips/checks as many bits as the datatypes require. I find this implementation more easy to understand. Commit is in <a href="https://github.com/Igalia/mesa/commit/59fd1cc6b99dc993e0da772674a57390a54955f3">https://github.com/Igalia/mesa/commit/59fd1cc6b99dc993e0da772674a57390a54955f3</a></pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the QA Contact for the bug.</li> </ul> </body> </html>