<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW - Elemental demo compute shader takes ages to compile" href="https://bugs.freedesktop.org/show_bug.cgi?id=95438#c1">Comment # 1</a> on <a class="bz_bug_link bz_status_NEW " title="NEW - Elemental demo compute shader takes ages to compile" href="https://bugs.freedesktop.org/show_bug.cgi?id=95438">bug 95438</a> from <a class="email" href="mailto:bas@basnieuwenhuizen.nl" title="Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>"> Bas Nieuwenhuizen</a> <pre>Last I looked at the elemental demo, we have multiple issues: - The shared array (1024 elements) get wrongly promoted to a private array. There is a fix for that at <a href="https://lists.freedesktop.org/archives/mesa-dev/2016-April/113832.html">https://lists.freedesktop.org/archives/mesa-dev/2016-April/113832.html</a> - in radeonsi we compile arrays to vectors with insert/extract element. This pretty much results in the array being SSA version, which results in a very large program. - a 1024 element vector does not fit in 256 VGPR's so LLVM tries to load and spill around every operation and therefore every versioned array element takes scratch space. - As a result I needed 7 MiB of scratch space per wave, or 6,7 GiB in total. This overflows the 32-bit buffer size and we only allocate a smaller buffer. - This resulted in hangs (or maybe long long shader execution times, not really sure...). So not sure how long a long long time is, last I tried (which admittedly is some weeks ago) I certainly could get past the compilation stage. If you did get past that and did not get hangs, I'm not sure why. Fixing the first problem also circumvents problems 2 & 3, although it would be nice to get those fixed as well.</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the assignee for the bug.</li> </ul> </body> </html>