Functionality added to the WebGPU spec after its first shipment in a browser. A new TRANSIENT_ATTACHMENT GPUTextureUsage lets developers create attachments that allow render pass operations to stay in tile memory, avoiding VRAM traffic and potentially avoiding VRAM allocation for the textures.
When a texture is declared transient (or "memoryless"), the GPU knows that the contents of that texture are only needed temporarily—specifically, only within the current render pass. Moreover, since the texture contents are discarded after the render pass, the driver may not even need to allocate space for that texture in the main VRAM at all. Even without hardware support for transient attachments, the hint can be used to reuse the allocation of transient textures between passes, which reduces peak memory usage. https://github.com/gpuweb/gpuweb/pull/5450
Explainers: https://github.com/gpuweb/gpuweb/blob/main/proposals/transient-attachments.md