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fix(shader): group compute derivatives by four consecutive lanes - #5829
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A compute shader with an LOD query was emitted with DerivativeGroupQuadsKHR, which needs both workgroup dimensions even. A guest workgroup of N x 1 lanes failed SPIR-V validation (VUID-StandaloneSpirv-DerivativeGroupQuadsKHR-10151), which agc_driver_waterfall_images hits on every device. GFX10 forms a compute quad from four consecutive lanes, which is DerivativeGroupLinearKHR. The wave64 path no longer reshapes its workgroup to 2 x N, which only made the 2D quads match consecutive lanes.
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… tables A waterfall loop over a T# that each lane loaded with IDXEN buffer loads (s_ff1/v_readfirstlane, v_readlane of the eight dwords, v_cmpx_eq against the lane's VGPRs, the image instruction) stopped planning with "GetImageResource dword 0 is not a valid runtime value". Bring back the fold of boykopovar#5089 (reverted by boykopovar#5824 for a derivative-group validation error that boykopovar#5829 fixed) on the image table model of boykopovar#757: the T# dwords are the lane's own VGPRs under the loop's EXEC, and the access reads an image table column keyed by the lane's buffer index, with the V#'s stride and NUM_RECORDS addressing of the recompiler's buffer loads, a record count in the table header, NonUniform slots, and whole-table faults for V# layouts and for mixed image modes under implicit derivatives. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Co-Authored-By: Codex <noreply@openai.com>
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What
Fixes
agc_driver_waterfall_imageson main (Linux CI run 38562879025). The LOD-query cases from #5089 recompile a compute shader with an N x 1 workgroup, and the emitter declaredDerivativeGroupQuadsKHR, which needs both workgroup dimensions even:GFX10 forms a compute quad from four consecutive lanes, which is
DerivativeGroupLinearKHR, so the capability and execution mode switch to the linear form. The wave64 path no longer reshapes its workgroup to 2 x N; that reshape was only there to make 2D quads cover consecutive lanes.Tested
Linux, Release,
BUILD_TESTING=ON,ANYPS5_ENABLE_SPIRV_TOOLS=ON.agc_driver_waterfall_images: fails on main with the VUID above on lavapipe (LLVM 20.1.2,GALLIUM_OVERRIDE_CPU_CAPS=avx, subgroup 8, as CI) and on an RTX 4090 (X = 32); passes on both with this change.ctest -R "agc_|shader": 539/539 pass on lavapipe and on the RTX 4090.Checklist
main; no other open PR implements the same functionsNotImplemented_nid_no_patch); silent stubs are listed under Silent stubs in their library's technical debt file.mdfiles or images added to the repository (attach them to this PR)