Validate VUID-RuntimeSpirv-Location-06428

[Rua]

This VUID is not validated anywhere in the layer's source code:

VUID-RuntimeSpirv-Location-06428 The maximum number of storage buffers, storage images, and output Location decorated color attachments written to in the Fragment Execution Model must be less than or equal to maxFragmentCombinedOutputResources

[spencer-lunarg]

yes, this is similar to the maxFragmentDualSrcAttachments one (VUID-vkCmdDraw-maxFragmentDualSrcAttachments-09239) that we have coverage for

I remember I was going to do this one, but needed spec clarification (which was added https://gitlab.khronos.org/vulkan/vulkan/-/issues/2236) and just never got around back to adding this

[spencer-lunarg]

wow, so finally got to this and tried to implement it as

    // maxFragmentCombinedOutputResources
    if (stage == VK_SHADER_STAGE_FRAGMENT_BIT) {
        // Variables can be aliased, so use Location to mark things as unique
        vvl::unordered_set<uint32_t> color_attachments;
        vvl::unordered_set<uint32_t> storage_buffers;
        vvl::unordered_set<uint32_t> storage_images;
        for (const auto *variable : entrypoint.user_defined_interface_variables) {
            if (variable->storage_class == spv::StorageClassOutput && variable->decorations.location != spirv::kInvalidValue) {
                // even if using an array of attachments in the shader, each used variable of the array is represented by a single variable
                color_attachments.insert(variable->decorations.location);
            }
        }

        for (const auto& variable : entrypoint.resource_interface_variables) {
            if (variable.decorations.location == spirv::kInvalidValue) continue;
            if (variable.is_storage_buffer) {
                storage_buffers.insert(variable.decorations.location);
            } else if (variable.is_storage_image) {
                storage_images.insert(variable.decorations.location);
            }
        }
        const uint32_t total_output = (uint32_t)(color_attachments.size() + storage_buffers.size() + storage_images.size());
        if (total_output > limits.maxFragmentCombinedOutputResources) {
            skip |= LogError("VUID-RuntimeSpirv-Location-06428", module_state.handle(), loc,
                                "SPIR-V (Fragment stage) output contains %zu storage buffer locations, %zu storage image locations, and %zu color attachments which together is %" PRIu32 " which exceeds the limit maxFragmentCombinedOutputResources (%" PRIu32 ").", storage_buffers.size(), storage_images.size(), color_attachments.size(), total_output, limits.maxFragmentCombinedOutputResources);
        }
    }

but then writing tests, I realized I have no idea what the "storage buffer" means (like do we count each set or each binding to the limit?)

created https://gitlab.khronos.org/vulkan/vulkan/-/issues/3900 to try this spec fixing again :crying_cat_face:

update - found out this was before descriptor indexing (and those drivers should report something like uint32_t max here). Also each descriptor (so binding) would count as 1