iterationRP's Program 203 declares shared vec2 prefixSumCache[32] for a
512-invocation workgroup indexed by gl_SubgroupID; any device narrower
than 16 lanes partitions into more than 32 subgroups and the pack writes
shared memory out of bounds (heap corruption on lavapipe's CPU
rasterizer, ssim 0.028 on the CI retrace). Fix it where the fault lies -
in the fixture - and keep the GL contract sound everywhere else:
- FixIterationRPSubgroupScratchPass: fingerprint-gated SPIR-V pass that
grows exactly that array to ceil(invocations/width) entries on sub-16-lane devices; every other module passes through byte-identical.
- DeriveNumSubgroupsPass stays default-on for the Adreno topology bug
and is made spec-sound: pipelines request REQUIRE_FULL_SUBGROUPS
whenever the workgroup shape makes the flag legal (computeFullSubgroups
enabled, local_size_x a multiple of the native width, subgroup count
within maxComputeWorkgroupSubgroups).
- EmulateSubgroupsPass: 32-lane virtual-subgroup lowering kept in-tree
as a last resort, enabled only by MOBILEGL_MAGMA_EMULATE_SUBGROUP=1 on
devices with no native subgroup support; fails closed on extended
subgroup instructions and on modules whose added scratch would exceed
maxComputeSharedMemorySize.
- IterationRPFirstReductionScenario skips gracefully outside the pack's
16..256-lane source domain; the new IterationRPScratchFixScenario runs
the fixture-shaped reduction on any width and asserts the exact
width-independent total. DriverPost keeps reporting FAIL on
out-of-domain devices.
- Program203 -> IterationRP rename throughout; the per-trace
num_subgroups_quirk plumbing is removed from the trace replayer, JNI
chain, and CI workflows.
minecraft-1.21.4-fabric-iris-bsl-esc-menu-854: Minecraft 1.21.4 Fabric +
Sodium + Iris + BSL 10.1.3 through Espryt on Mali-G77, paused at the ESC
menu over the BSL-blurred world, captured at 854x480 through the FCL
trace-capture skill. The trimmed trace keeps the whole session preamble
deliberately: the 107669b3 bug class is triggered while Iris BUILDS the
pipeline (a by-name texture call swapping the active unit's binding under
the sync memo), and the pause menu afterwards is where its damage is
legible - every glyph alpha-discards against the zeroed lightmap while
the button frames survive.
Ablation-proven as a net before landing: against a build with both layers
of 107669b3 reverted the case fails at ssim 0.949284 and the diff image
is text and only text - menu title, all button labels, the tutorial
toast; against the fixed library it matches the golden exactly, and
Magma passes the same golden at 0.998402 with no alternate needed.
Replays in about a minute per backend on llvmpipe/lavapipe (the 1.3M-call
preamble; well under the timeout and smaller than several existing
fixtures). Existing fixtures spot-checked green.
Two 1.21.1 NeoForge Create in-world captures facing water wheels and a
large cogwheel, one per flywheel backend (/flywheel backend indirect and
instanced). The indirect trace exercises the compute scatter/cull
pipeline, glMultiDrawElementsIndirect with GPU-written commands, and
draw-parameter emulation; captured with persistent-map shadowing so the
unflushed scatter descriptors Flywheel writes are recorded. Both trimmed
to a single frame and brotli-repacked (~7 MiB each).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
swung0x48
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