sampler-feedback-without-streaming-flag
Status: stub. The full-length analysis is queued for a v1.0.x patch release per ADR 0018, section 5, criterion #6. The companion rule page at docs/rules/sampler-feedback-without-streaming-flag.md contains the canonical detection logic + GPU reasoning.
TL;DR
Sampler feedback (DirectX 12 Ultimate, SM 6.5+) is a hardware mechanism that records which mip and tile of a logical texture were actually sampled by a shader, into a small companion feedback surface. The intended consumer of that feedback is a streaming subsystem: the CPU reads the feedback texture, decides which tiles to page in or out, and updates the tiled-resource backing of the source texture for subsequent frames. The hardware path on AMD RDNA 2/3 (MIN_MIP and MIP_REGION_USED feedback formats), NVIDIA Turing/Ada (sampler feedback maps), and Intel Xe-HPG involves dedicated bookkeeping in the TMU to materialise the feedback tile and writes it into the feedback resource at every sample.
What the rule fires on
A shader that calls WriteSamplerFeedback, WriteSamplerFeedbackBias, WriteSamplerFeedbackGrad, or WriteSamplerFeedbackLevel against a FeedbackTexture2D / FeedbackTexture2DArray resource where reflection cannot find a corresponding tiled-resource (Texture2D with reserved/tiled binding flags, or a tier-2 sampler-feedback paired resource) attached to the same logical surface. The detector enumerates feedback-texture bindings via reflection and looks for the paired streaming-source binding metadata; it fires when the feedback writes appear without a streaming binding evidence.
See the What it detects section of the rule page for the full pattern definition.
Why it matters
The full GPU-mechanism analysis lives in the Why it matters on a GPU section of the companion rule page.
Examples
The bad / good code snippets are kept canonical on the rule page; see sampler-feedback-without-streaming-flag.md -> Examples.
See also
- Rule page -- canonical reference + change log.
- sampler-feedback overview -- broader context.
- ADR 0018 -- v1.0 readiness plan.
This is a v1.0-ship stub. Full analysis pending; track issue link TBD.