docs: describe shader modules and pipeline libraries built at registration

Co-Authored-By: Claude <noreply@anthropic.com>

docs/dev/ARCHITECTURE.md

@@ -91,6 +91,7 @@ flowchart LR
 - `Driver::RegisterShader` splits shader preparation in two. `PlanRegistered` runs on the registering guest thread: it validates the registers and entry point, decodes the code and builds the recompile request, so invalid registrations still fail there. The RDNA to IR translation and resource plan (`PrepareShader`) run on a background pool of `hardware_concurrency() / 2` detached threads (at least 2, 64 MiB stacks).
 - The shader registry maps a code address to every header registered for that code, in registration order. Static, graphics and rectangle ABI resolution pick the header at the bound address (or one equal to it, `SameHeader`, which also takes a hull header fused by `sceAgcFuseShaderHalves` (type 3) as the registered back half (type 7) it copies, the fused registers aside; graphics ABI resolution then uses the fused header's shader registers); draws and dispatches pick the program by the stage's binary type (`RegisteredProgram`), and a front entry matching both type 2 and type 4 throws. Within a type the last registration wins; re-registering an identical earlier header makes its snapshot current again without preparing it again, and changed code drops the older headers.
 - The snapshot is published as pending. `SourceHandleFor`, `InvocationFor` and `ShaderPreparationTransaction::Edit` / `Read` wait for the pending job before reading `PreparedShaders`, and rethrow its failure. `APS5_SYNC_SHADER_PREPARE=1` prepares on the registering thread instead.
+- On devices with graphics pipeline libraries (`SpirvTarget::registrationModules`), a vertex or pixel artifact is emitted in registration form: the buffer V# words, image modes, swizzles and mip ranges, depth-compare state, export mappings and vertex component selectors it used to specialize on per draw are read at run time (image `ResourceMetadata` and a few state dwords in the shader data), descriptor heaps keep every element in place (an unused one gets a null or placeholder descriptor), and the pixel stage's bindings live in descriptor set 1 so each stage's library depends only on its own set layout (`INDEPENDENT_SETS`). An artifact above `registrationWordLimit` SPIR-V words is re-emitted specialized, and `CompiledShaderArtifact::registrationModule` records which form it has. For artifacts in registration form, `RegistrationResult` materializes the module once, and `PrebuildStageLibrary` builds its pre-rasterization or fragment-shader library on a separate one-thread pool (`APS5_PREBUILD_THREADS`) with a fixed default state, pairing it with a stub stage. A later draw with that state finds both libraries in the store and only links.
 - A draw or dispatch whose state matches no artifact prepared at registration (a title that builds its static ABI state itself, without `sceAgcDriverResolve*Abi`) gets one prepared at use by `SourceHandleFor` or `InvocationFor`, logged once per artifact and kept in the snapshot for the next use.
 - A compute shader whose `s_swappc_b64` calls a user-data pointer cannot be linked at registration, because the callee's address is only known at dispatch. `InvocationFor` in [`ShaderRegistry.cpp`](../../core/libs/prx/libSceAgcDriver/Execution/src/Driver/Shaders/ShaderRegistry.cpp) reads each callee from guest memory, appends one copy per call after the caller (`LinkUserDataCalls`) and prepares that linked code, so a different callee gets its own prepared entry.
 - A draw's `Graphics::Pipeline` comes from `CachedPipeline`. When the device has `VK_EXT_graphics_pipeline_library` with fast linking, `VK_EXT_extended_dynamic_state` and `VK_KHR_dynamic_rendering`, draws render with `vkCmdBeginRenderingKHR` instead of render passes and the pipeline is linked from four libraries (vertex input, pre-rasterization shaders, fragment shader, fragment output) kept per device in [`PipelineLibrary.cpp`](../../core/libs/prx/libSceAgcDriver/Graphics/src/PipelineLibrary.cpp). A library built for one pipeline is reused by the next: another blend, vertex layout or target format builds only that part (the shader libraries name no attachment format), and cull mode, front face, depth and stencil state are dynamic, so changing them only links. The fast link is what the draw waits for; a background thread then links the same libraries with link-time optimization and the pipeline binds that one from the next draw on. Push constants then use a 256-byte block with a 128-byte slot per side: the pre-rasterization stages stack from byte 0, the pixel shader always starts at byte 128 (`StagePushOffset`), so its library does not depend on how much push data its vertex shader uses. Pipelines with per-face depth bias, a separate alpha blend into an 8_8 target with the alternate component order (both draw twice), rect lists, geometry shaders or a stage without a variant id are created whole, still with dynamic rendering; devices without the extensions (or with `APS5_NO_GPL=1`) keep render passes and whole pipelines.

docs/dev/TechnicalDebt.md

@@ -405,6 +405,8 @@ Throughout the project, every function at every stage either **does exactly what
 - [Compute LDS beyond the device's shared-memory limit](../../core/libs/prx/libSceAgcDriver/Execution/src/VulkanDevice.cpp) (libSceAgcDriver) lives in a coherent storage buffer with one slice of `LDS bytes / 4 + 1` dwords per workgroup (the last dword is the atomic lock), shared by all such dispatches and grown in 1 MiB steps up to `maxStorageBufferRange`; a dispatch whose slices do not fit throws. It is slower than shared memory and its cost was not measured. An indirect dispatch of such a program always reads its group counts on the CPU. Its results are pinned against the in-limit semantics in `agc_driver_lds_beyond_device_limit`, not measured on hardware.
 - [AGC buffer allocations](../../core/libs/prx/libSceAgcDriver/Graphics/src/BufferPool.cpp) retry host/device out-of-memory once after reclaiming idle pool buffers and fully unused slab blocks. Live buffers and blocks with live slots are retained. Live images and other retained resources have no global memory bound; allocation failure still throws when reclaim cannot satisfy the request.
 - [Graphics pipeline libraries](../../core/libs/prx/libSceAgcDriver/Graphics/src/PipelineLibrary.cpp) (libSceAgcDriver): a pipeline is fast-linked at the draw and relinked with `VK_PIPELINE_CREATE_LINK_TIME_OPTIMIZATION_BIT_EXT` on a background thread, and binds the optimized one from the next draw on. Draws recorded before that use the fast link, whose vertex stage keeps the outputs the fragment stage does not read: on RADV (Radeon 660M, Mesa 26.2.4) 346 of 483 Astro's Playroom vertex shaders paired with a fragment stage that reads none of them used more VGPRs (median 8 more, up to 2.5 times), and on an RTX 4090 13 of 15 PPSA36082 vertex shaders up to 68 instead of 38 (#2242). The optimized link compiles to the same code as a whole pipeline
+- [Shader modules built at registration](../../core/shader/recompiler/Recompiler.cpp) (shader recompiler): on devices with graphics pipeline libraries a module reads buffer V# words, image modes, swizzles and mip ranges, depth-compare state, export mappings and vertex component selectors at run time instead of specializing on them per draw, so its libraries can be built when the shader is registered. A module that would exceed `SpirvTarget::registrationWordLimit` (200000 SPIR-V words) is emitted specialized as before: on RADV (Radeon 660M, Mesa 26.2.4) a sample of 60 Astro's Playroom pixel shaders compiled 1.9 to 2.2 times slower in registration form below 141k words and 3.8 to 5.7 times slower above 280k words (none in between), so the limit sits in that gap; it was not measured on other drivers. Texel-offset folding and the vertex attribute numeric class stay specialized, and a pixel shader whose image needs a multisampled descriptor gets no registration result; these, and every draw whose fixed-function state differs from the prebuild's, still build their libraries at the draw.
+- [Prebuilt pipeline libraries](../../core/libs/prx/libSceAgcDriver/Execution/src/VulkanDevice.cpp) (libSceAgcDriver): each registered vertex or pixel shader in registration form gets its pre-rasterization or fragment-shader library built on one background thread, with a fixed state the draw may not use: triangle list, counter-clockwise front face, no depth clamp, depth bias or conservative rasterization, first provoking vertex, one sample. Libraries are kept until the device is torn down; on Astro's Playroom 1948 of them added 0.44 GB of peak memory on RADV.
 - [sceAvPlayerGetVideoData](../../core/libs/prx/libSceAvPlayer/src/Source.cpp) (libSceAvPlayer) in sync mode `SCE_AVPLAYER_AV_SYNC_MODE_NONE` skips queued frames that the audio clock has already passed while the title pulls audio, so a title that requests video slower than the film's frame rate keeps the picture with the sound. Whether the console hands out every frame in this mode is unknown. PPSA12544 requests 7-19 frames per second for a 30 fps cinematic
 - [`APS5_THREAD_PRIORITY=rt`](../../core/libs/prx/libSceAgcDriver/Execution/src/ThreadPriority.cpp) (libSceAgcDriver) lowers the process's hard `RLIMIT_RTTIME` when it is above `APS5_THREAD_RTTIME_US` or rtkit's `RTTimeUSecMax`, because [rtkit](https://github.com/heftig/rtkit/blob/c295fa849f52b487be6433e69e08b46251950399/rtkit-daemon.c#L592-L637) (`verify_process_rttime`) reads the hard limit from `/proc/<pid>/limits` and refuses real-time scheduling when it is higher. An unprivileged process cannot raise the hard limit again, so it stays lowered for the process and its threads even when rtkit then refuses the request (burst limit, user or start-time checks) and the thread throws. rtkit's `MaxRealtimePriority` and `RTTimeUSecMax` are read first, so an unreachable rtkit or a priority above its maximum leaves the limit untouched. The lowered limit only matters for threads that later run under a real-time policy
 - On a device without VK_EXT_robustness2's `nullDescriptor`, such as MoltenVK, a null image descriptor in a typed heap is a [placeholder image](../../core/libs/prx/libSceAgcDriver/Graphics/src/PlaceholderImages.cpp) of that heap's type, 1×1 and cleared to zero, which every null descriptor of the heap shares. Reads give zeros, as `nullDescriptor` allows, but stores and atomics to it are kept, so a later read of a null storage image can return them, and a depth comparison compares against depth 0. A heap whose placeholder the device cannot create, for example 1D or 3D depth, 64-bit atomics without 64-bit image atomics, or multisampled storage without `shaderStorageImageMultisample`, throws when a null descriptor reaches it.