<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW - [i965] Compiler backend uses too much stack with Alien: Isolation" href="https://bugs.freedesktop.org/show_bug.cgi?id=93840#c33">Comment # 33</a> on <a class="bz_bug_link bz_status_NEW " title="NEW - [i965] Compiler backend uses too much stack with Alien: Isolation" href="https://bugs.freedesktop.org/show_bug.cgi?id=93840">bug 93840</a> from <a class="email" href="mailto:eero.t.tamminen@intel.com" title="Eero Tamminen <eero.t.tamminen@intel.com>"> Eero Tamminen</a> <pre>(In reply to Darius Spitznagel from <a href="show_bug.cgi?id=93840#c32">comment #32</a>) > are there any news on this? I've provided Matt with apitrace of the startup, so he can investigate the compiler side. > SKL and HSW are very different. > Did you test mesa git with HSW instead of SKL? Don't have a set up where I could try the real game on one, but apitrace replay didn't compile instruction-count-wise as large CS shaders as SKL (before it failed to run rest of the trace), this was the largest: 43621: message: shader compiler issue 653: CS SIMD16 shader: 5210 inst, 0 loops, 118772 cycles, 207:471 spills:fills, Promote d 0 constants, compacted 83360 to 58672 bytes. Btw. I tried Apitrace trace on BDW and as expected, it had the same issue as SKL. Perf says time is spent in intel backend: ----------------------- Overhead Symbol 47,44% ra_allocate 15,38% fs_visitor::virtual_grf_interferes 12,04% fs_visitor::assign_regs 8,95% ra_add_node_adjacency 2,98% decrement_q.isra.2 1,63% ra_add_node_interference ----------------------- Which seems very similar to <a class="bz_bug_link bz_status_CLOSED bz_closed" title="CLOSED FIXED - Older UnrealEngine v4 demos compute shaders compilation never finishes" href="show_bug.cgi?id=98455">bug 98455</a>. > Maybe Xorg does play a role here? Forgot to mention my current Xorg version > in last post... > > xserver-xorg-core 1.19.1 X version should have no impact on what gets compiled in compute shader. On BDW+, SIMD32 is needed to satisfy compute workgroup requirements, but from the Apitrace output it seems that on HSW SIMD16 is enough, and that requires a lot less registers. -> That explains why things works on HSW, but not on anything newer. >3x larger number of registers needs more stack to process and is *much* slower to compile (it spills a lot).</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the QA Contact for the bug.</li> </ul> </body> </html>