docs(technical-debt): record the NVIDIA proprietary pipeline relink skip
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@ -418,6 +418,7 @@ Throughout the project, every function at every stage either **does exactly what
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- [Unnormalized texel offsets](../../core/shader/recompiler/SpirvBackend/src/SpirvImageEmitter.cpp) are added to the f32 coordinates: exact on RDNA2 (gfx1035), which applies the offset before the clamp ([measured by adriadam10](https://github.com/boykopovar/AnyPS5/pull/822#issuecomment-6033192725)).
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- [Image atomics](../../core/shader/recompiler/Optimization/src/ResourceMaterializer.cpp) on 32_SINT and 32_FLOAT surfaces act on the raw dword through an R32_UINT storage view; their float results are assumed to match those measured on 32_UINT surfaces. Other formats throw.
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- [`s_memtime`](../../core/shader/recompiler/SpirvBackend/src/SpirvModuleEmitter.cpp) on RADV with a GFX10.3 to GFX11.7 GPU (RDNA 2, RDNA 3, RDNA 3.5) reads the Vulkan device clock instead of the subgroup clock, which [ACO](https://gitlab.freedesktop.org/mesa/mesa/-/blob/main/src/amd/compiler/instruction_selection/aco_select_nir_intrinsics.cpp) reads from the 20-bit `SHADER_CYCLES` register there and which wraps every 2^20 cycles. The device clock is a monotonic 64-bit counter, but it counts the 100 MHz reference clock (the same one as `s_memrealtime`), not shader cycles, so `s_memtime` deltas are about 20 times smaller than on hardware. The families are matched by the name RADV reports ([`NarrowSubgroupClock`](../../core/libs/prx/libSceAgcDriver/Execution/src/SubgroupClock.cpp)); a family added to Mesa later reads the subgroup clock until it is listed. AMD's proprietary Windows driver also exposes a 20-bit subgroup clock on device 0x1114 (Radeon 860M, measured in #1615), device 0x744c (Radeon RX 7900 XT, measured in #1632), and device 0x747e (Radeon RX 7800 XT, measured in #1632); other AMD proprietary devices remain unverified.
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- [Background link-time-optimized relink of library pipelines](../../core/libs/prx/libSceAgcDriver/Execution/include/PipelineLinkOptimization.hpp) (libSceAgcDriver) is skipped on every GPU under NVIDIA's proprietary Vulkan driver (`VK_DRIVER_ID_NVIDIA_PROPRIETARY`), so those pipelines keep their fast-linked form. The optimized link loses the device when bound on an RTX 3080 (Ampere, #2866) and an RTX 4060 (Ada, #3434); an RTX 5060 and an RTX 5080 (Blackwell) on the same driver do not, so the scope is wider than the evidence. No standard Vulkan query tells the architecture apart, and the driver version that fixes it is unknown. `APS5_NO_PIPELINE_LTO` disables the relink on every driver.
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- [`s_memtime` and `s_memrealtime`](../../core/shader/recompiler/SpirvBackend/src/SpirvModuleEmitter.cpp) on llvmpipe read only the low 32 bits of the host's nanosecond clock at either scope: Mesa's [`emit_clock`](https://gitlab.freedesktop.org/mesa/mesa/-/blob/main/src/gallium/auxiliary/gallivm/lp_bld_nir_soa.c) builds the high dword with a left shift by 32, so it is always 0 and both counters wrap every 2^32 ns (about 4.3 s). The [shader clock test](../../core/libs/prx/libSceAgcDriver/tests/execution/ShaderClock.cpp) compares them modulo 2^32 there
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- [`ds_wrxchg2_rtn_b32`, `ds_wrxchg2st64_rtn_b32`, `ds_wrxchg2_rtn_b64` and `ds_wrxchg2st64_rtn_b64`](../../core/shader/recompiler/Translation/src/MemoryInstructions/SharedMemoryInstructions.cpp) are translated as two separate 32-bit or 64-bit atomic swaps per invocation. RDNA2 hardware (measured on gfx1035) performs every lane's first exchange before any lane's second one, so when lanes of the same wave or of different waves overlap addresses, the result can differ from hardware. `offset0 == offset1` throws, although on hardware it is two exchanges in order.
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- [`ds_condxchg32_rtn_b64`](../../core/shader/recompiler/Translation/src/MemoryInstructions/SharedMemoryInstructions.cpp) uses two 32-bit atomic conditional exchanges. RDNA2 (gfx1035) measurements confirmed aligned return values, conditional bit clearing and 16-bit offsets; out-of-range accesses return zero without modifying LDS. Misaligned accesses fault the wave on gfx1035; the recompiler does not model this fault. Radeon 780M (gfx1103, RDNA3) measurements confirmed aligned return values, conditional bit clearing, EXEC masking and operand overlap in wave32 and wave64; contended cases passed per-dword conservation checks. Contended lane ordering and gfx1013 remain unmeasured; pair-wide indivisibility is not assumed, and concurrent 64-bit LDS atomics use a separate lock. GDS throws. VGPR pairs extending beyond v255 throw; allocated-VGPR EXEC nullification is not emulated.
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