mirror of
https://gitlab.freedesktop.org/mesa/mesa.git
synced 2026-05-26 12:28:12 +02:00
a48ecca4d9
This works around a long-standing synchronization issue consequence of the HALT instruction used to implement FS discard not being considered a control flow instruction by the back-end -- The fact that it doesn't cause the CFG pass to introduce an edge in the graph means that the software scoreboard pass is completely blind to the effect of discard jumps on control flow, so it doesn't introduce the required annotations to avoid data hazards when the discard path of the CFG is taken. Note that because of the very limited set of instructions that can follow the HALT target in a fragment shader this was very unlikely to lead to issues in practice, but starting on xe3 it appears to have become far more likely due to the use of SENDG, since SENDG requires the scalar register to be set prior to the submission of the render target write payloads, which can easily lead to a WaR hazard if there was another SENDG before the HALT jump that wasn't done reading out its payload from the GRF. In an ideal world this would be avoided by having HALT be a normal control flow instruction represented as an edge in the control flow graph -- But unfortunately that would prevent the optimizations we currently do that take advantage of the ability of reordering code past the HALT instruction, so it would have a pretty large performance cost. Instead this simply adds a SYNC.ALLWR instruction after the HALT target to guarantee that all pending SEND messages have finished execution -- That may also seem costly, however its cost in practice appears to be minimal since at the point of the program when the target HALT is executed there is almost nothing left to do other than send out the render target write payloads, so any pending operations had to be waited on at roughly this point of the program regardless. There appear to be no statistically significant regressions in Traci on neither BMG nor PTL. Fixes hangs observed on Dying Light 2 and Cyberpunk on PTL. Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/13896 Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/13965 Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/14092 Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@intel.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/37674> |
||
|---|---|---|
| .. | ||
| amd | ||
| android_stub | ||
| asahi | ||
| broadcom | ||
| c11 | ||
| compiler | ||
| drm-shim | ||
| egl | ||
| etnaviv | ||
| freedreno | ||
| gallium | ||
| gbm | ||
| getopt | ||
| gfxstream | ||
| glx | ||
| gtest | ||
| imagination | ||
| imgui | ||
| intel | ||
| loader | ||
| mesa | ||
| microsoft | ||
| nouveau | ||
| panfrost | ||
| tool | ||
| util | ||
| virtio | ||
| vulkan | ||
| x11 | ||
| .clang-format | ||
| meson.build | ||