[perf][LOW] nonuniformEXT on dynamically-uniform font slots (text shader) #49

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opened 2026-06-16 16:51:31 +02:00 by jorijnvdgraaf · 0 comments

jorijnvdgraaf commented

2026-06-16 16:51:31 +02:00

Owner

Subsystem: UI GLSL shaders
Location: shaders/ui-text.comp.glsl:39-43
Impact: LOW · Effort: Small

Problem

pc.fontTextureSlot/pc.fontSamplerSlot are push constants (provably dynamically uniform) but wrapped in nonuniformEXT, forcing the per-invocation divergent-descriptor path and inhibiting hoisting the uniform load out of the per-pixel loop.

Proposed fix

Drop nonuniformEXT on the text shader's push-constant font slots only. Zero correctness risk — it is a read-index decoration.

Correctness caveat

Do not apply to ui-images.comp.glsl — its texSlot/sampSlot come from an SSBO load, which the compiler cannot prove uniform. Text-shader push constants only.

**Subsystem:** UI GLSL shaders **Location:** `shaders/ui-text.comp.glsl:39-43` **Impact:** LOW · **Effort:** Small ### Problem `pc.fontTextureSlot`/`pc.fontSamplerSlot` are push constants (provably dynamically uniform) but wrapped in `nonuniformEXT`, forcing the per-invocation divergent-descriptor path and inhibiting hoisting the uniform load out of the per-pixel loop. ### Proposed fix Drop `nonuniformEXT` on the **text shader's push-constant font slots only**. Zero correctness risk — it is a read-index decoration. ### Correctness caveat Do **not** apply to `ui-images.comp.glsl` — its `texSlot`/`sampSlot` come from an SSBO load, which the compiler cannot prove uniform. Text-shader push constants only.

jorijnvdgraaf added the

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2026-06-16 17:18:50 +02:00