vertexBuffer/indexBuffer/aabbBuffer were HOST_VISIBLE (system RAM), so the
BLAS build, every refit, and any hit-shader geometry fetch read them over
PCIe. The usage flags (SHADER_DEVICE_ADDRESS, plus STORAGE on the index
buffer) exist precisely to expose geometry for hit-shader fetch, the dominant
RT shading pattern.
Add VulkanBuffer::UploadDeviceLocal, which places a CPU-written/GPU-read
buffer in device-local memory and picks the upload mechanism at runtime via
the #89 strategy (Device::PreferDirectDeviceWrite):
- ReBAR/UMA: allocate HOST_VISIBLE|DEVICE_LOCAL (DEVICE_LOCAL preferred),
map transiently, memcpy, flush-if-non-coherent. No staging buffer.
- no/small BAR: allocate pure DEVICE_LOCAL + TRANSFER_DST, fill a transient
HOST_VISIBLE staging buffer, vkCmdCopyBuffer, then DeferredClear the
staging buffer onto the fence-keyed deletion queue (#101/#102) so it
outlives the copy submit.
The geometry buffers become non-mapped so the destination is free to be
device-local-only. Same-size re-uploads reuse the allocation, so the device
address stays stable across an in-place AS UPDATE refit. The compressed Build
path now allocates vertex/index as pure DEVICE_LOCAL — the GPU decompressor
fills them directly, no host write.
Tests: BLASBuildOptions asserts device-local placement on the triangle,
procedural, and (budget-forced) staged paths, and exercises the staged copy +
deferred-deletion + in-place refit under GPU-assisted validation with zero
validation errors.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
A static (!allowUpdate) mesh can never refit, so its per-mesh DEVICE_LOCAL
scratch buffer is dead weight the moment the build's GPU work completes —
yet it was kept alive for the mesh's whole lifetime. In many-mesh scenes
(where static meshes dominate) this is real, accumulating VRAM waste.
Release it via scratchBuffer.DeferredClear() right after recording a fresh
build for a static mesh. The old "free-after-build is a UAF, the GPU is
still building" hazard is gone: the fence-keyed deferred-deletion queue
(#101/#102) retires the allocation only once the build's frame has passed
its fence. A later Refit on a static mesh takes the rebuild fallback, whose
Resize sees the nulled handle and re-Creates the scratch. Refit-capable
(allowUpdate) meshes keep their scratch as before — an in-place UPDATE
reuses it each frame.
Extends the BLASBuildOptions hardware test to assert the scratch is retained
for allowUpdate meshes and released for static ones (including across a
static-mesh refit rebuild), with the validation layer confirming zero errors.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Extend BLASBuildOptions with a device-local AABB buffer filled via a staging
copy + barrier (standing in for a GPU compute producer) fed into the new
device-address BuildProcedural/RefitProcedural. Asserts the build/refit
succeed, the in-place UPDATE keeps the AS handle + blasAddr, the host
aabbBuffer is never allocated (proof of zero-copy), and the validation layer
reports no errors.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Exercises the real hardware AS-build path: builds and refits triangle
and procedural BLASes with fast-build/fast-trace + allow-update flags
via one-time command buffers, asserting the requested flags land, that
an allowUpdate refit keeps the same AS handle/blasAddr (in-place
UPDATE), that the no-update / topology-change fallback still produces a
valid BLAS, and that the validation layer reports zero errors.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
