Some background: my shader render pipeline uses SPIRV-Cross to convert SPIR-V into Metal shaders. For resource binding, argument buffers are used, mapping directly to Vulkan descriptor sets. Crucially, these argument buffers are shared across pipeline stages; each argument buffer may contain resources relevant to both the vertex and fragment stage.

As a result of this, I need all bindings to be visible to all shader stages, even if the binding may be unused in that stage: the argument buffer definition must be complete. To achieve this, the AggressiveDCE pass must not strip instructions with binding decorations. (Additional changes are also needed for SPIRV-Cross to support this; see troughton/SPIRV-Cross@c3daef7)

Note that simply not running the pass isn't an option; my source shaders are in HLSL so need to undergo legalisation.

I don't expect this to be merged as-is (since that would obviously be undesirable for code-size in a number of shaders), but I welcome suggestions for how retaining bindings should be added as an option – should it be added an option to AggressiveDCE, or should a separate pass be used? How should the option be exposed in the driver?