turnip: gfxbench vk-5-normal slower than freedreno gl-5-normal
GL gets about 17-18fps, turnip 12fps, at 1920x1080 on desktop Linux. Had to hack it to choose ASTC for vulkan, at which point image layouts looked similar.
- vk is all 32-bit samplers, while gl has many 16-bit samplers
- vk has almost no 16-bit math, while gl has lots
- vk has a bit more ldp/stp: 1144/826 vs 1075/739 (and, again, 32 vs 16)
- FD_MESA_DEBUG=nofp16 doesn't do much to freedreno, though (maybe half an fps)
- !15974 (merged) doesn't trigger