[CleoMenezesJr]

Builds on #1507 (its three commits are included until it is merged; only the last commit is new).

Problem

On an RX 5500 XT (RDNA1 / NAVI14, Mesa RADV, Fedora, no mesh shaders so the compute mesh fallback runs), objects such as the ladder of Link's house in Kokiri Forest flipped frame to frame between correct, speckled/dotted and glowing white while moving or turning the camera (the "moving" half of #1126 / #997).

Bisect

Switches set in the game folder's hookshot_env.txt, same spot each run:

Switches	Flicker
RX_VK_NO_DESC_REUSE=1, RX_VK_PICK_BIND_GEN=1	yes
+ RX_VK_PER_QUEUE_FENCES=0, RX_VK_SAMPLER_CACHE=0, RX_VK_MIRROR=0	yes
+ RX_VK_BARRIER_EVERY_DRAW=1, RX_VK_WAIT_GPU=1, RX_VK_HANDLES_LIVE=1, RX_VK_BATCH=0, RX_VK_NO_EVICT=1	yes
RX_VK_WARP64=0 + RX_VK_FRAG_SHUFFLE_FALLBACK=1	no
RX_VK_FRAG_SHUFFLE_FALLBACK=1 alone	no

Change

has_broken_spirv_fragment_shuffle is now on for VK_DRIVER_ID_MESA_RADV as well as VK_DRIVER_ID_AMD_PROPRIETARY. tests/test_amd_fragment_warp.py is updated and passes.

• RX_VK_FRAG_SHUFFLE_FALLBACK=0 still keeps native shuffles.
• The flag is in the program cache stamp, so RADV users retranslate once.

Testing

Tested on RDNA1 only. Other RADV GPUs (RDNA2/3/4, APUs) are untested. Reports welcome; if it turns out RDNA1-specific, the check can be narrowed.

[Joey-Magnus]

The change is one line, and the test passes on current main (I merged it locally and ran tests/test_amd_fragment_warp.py). But two things changed since you bisected. #1657 merged after this was opened. It handles RDNA1's wave32/wave64 stages: unpinned stages now take subgroup_max, which was the RX 5500 XT family's problem, and that may be what fixed the ladder. Could you re-run the same spot on current main without this patch, with RX_VK_FRAG_SHUFFLE_FALLBACK unset? Second, this turns the fallback on for every RADV device, Steam Deck included. On RADV max_subgroup_size is 64, so each fragment shuffle becomes 64 broadcasts and selects (ShuffleAbsolute in emit_spirv_warp.cpp). That's the most-used Linux AMD tier, and the cost hasn't been measured. If the flicker is still there on main, I'd narrow the check to RDNA1 or bring a Deck frame-rate number. CI hasn't run on this branch.