For example, if a shader has storage buffers A and B, is any overlap allowed between the two?

How about different usages, e.g. A is a storage buffer, and B is a texel buffer, or B is a texture that we might be sampling.

I'm trying to get at whether data races can occur due to conflicting accesses across different resources. If this is disallowed, then it's a property to be verified at command buffer recording time. It would likely also simplify the memory model within the shader.

Related issues:

• Investigation: Render Target Aliasing #63: Render target aliasing. Limited to render targets, and concerned about sharing between render passes, not within a render pass. Also, the resolution is postponed beyond MVP
• Proposal: BufferSubRanges to solve buffer-tracking, streaming and descriptor set explosion. #156, Proposals for buffer operations (immediate uploads, buffer mapping) #138: Buffer mappings, and subbuffers. I'm not sure it addresses aliasing within a shader instance.