C Specification

The VkSubpassDependency structure is defined as:

// Provided by VK_VERSION_1_0
typedef struct VkSubpassDependency {
    uint32_t                srcSubpass;
    uint32_t                dstSubpass;
    VkPipelineStageFlags    srcStageMask;
    VkPipelineStageFlags    dstStageMask;
    VkAccessFlags           srcAccessMask;
    VkAccessFlags           dstAccessMask;
    VkDependencyFlags       dependencyFlags;
} VkSubpassDependency;

Members

Description

If srcSubpass is equal to dstSubpass then the VkSubpassDependency describes a subpass self-dependency, and only constrains the pipeline barriers allowed within a subpass instance. Otherwise, when a render pass instance which includes a subpass dependency is submitted to a queue, it defines a memory dependency between the subpasses identified by srcSubpass and dstSubpass.

If srcSubpass is equal to VK_SUBPASS_EXTERNAL, the first synchronization scope includes commands that occur earlier in submission order than the vkCmdBeginRenderPass used to begin the render pass instance. Otherwise, the first set of commands includes all commands submitted as part of the subpass instance identified by srcSubpass and any load, store or multisample resolve operations on attachments used in srcSubpass. In either case, the first synchronization scope is limited to operations on the pipeline stages determined by the source stage mask specified by srcStageMask.

If dstSubpass is equal to VK_SUBPASS_EXTERNAL, the second synchronization scope includes commands that occur later in submission order than the vkCmdEndRenderPass used to end the render pass instance. Otherwise, the second set of commands includes all commands submitted as part of the subpass instance identified by dstSubpass and any load, store or multisample resolve operations on attachments used in dstSubpass. In either case, the second synchronization scope is limited to operations on the pipeline stages determined by the destination stage mask specified by dstStageMask.

The first access scope is limited to access in the pipeline stages determined by the source stage mask specified by srcStageMask. It is also limited to access types in the source access mask specified by srcAccessMask.

The second access scope is limited to access in the pipeline stages determined by the destination stage mask specified by dstStageMask. It is also limited to access types in the destination access mask specified by dstAccessMask.

The availability and visibility operations defined by a subpass dependency affect the execution of image layout transitions within the render pass.

Note

For non-attachment resources, the memory dependency expressed by subpass dependency is nearly identical to that of a VkMemoryBarrier (with matching srcAccessMask and dstAccessMask parameters) submitted as a part of a vkCmdPipelineBarrier (with matching srcStageMask and dstStageMask parameters). The only difference being that its scopes are limited to the identified subpasses rather than potentially affecting everything before and after.

For attachments however, subpass dependencies work more like a VkImageMemoryBarrier defined similarly to the VkMemoryBarrier above, the queue family indices set to VK_QUEUE_FAMILY_IGNORED, and layouts as follows:

  • The equivalent to oldLayout is the attachment’s layout according to the subpass description for srcSubpass.

  • The equivalent to newLayout is the attachment’s layout according to the subpass description for dstSubpass.

Valid Usage
  • VUID-VkSubpassDependency-srcStageMask-00860
    If the geometry shaders feature is not enabled, srcStageMask must not contain VK_PIPELINE_STAGE_GEOMETRY_SHADER_BIT

  • VUID-VkSubpassDependency-dstStageMask-00861
    If the geometry shaders feature is not enabled, dstStageMask must not contain VK_PIPELINE_STAGE_GEOMETRY_SHADER_BIT

  • VUID-VkSubpassDependency-srcStageMask-00862
    If the tessellation shaders feature is not enabled, srcStageMask must not contain VK_PIPELINE_STAGE_TESSELLATION_CONTROL_SHADER_BIT or VK_PIPELINE_STAGE_TESSELLATION_EVALUATION_SHADER_BIT

  • VUID-VkSubpassDependency-dstStageMask-00863
    If the tessellation shaders feature is not enabled, dstStageMask must not contain VK_PIPELINE_STAGE_TESSELLATION_CONTROL_SHADER_BIT or VK_PIPELINE_STAGE_TESSELLATION_EVALUATION_SHADER_BIT

  • VUID-VkSubpassDependency-srcSubpass-00864
    srcSubpass must be less than or equal to dstSubpass, unless one of them is VK_SUBPASS_EXTERNAL, to avoid cyclic dependencies and ensure a valid execution order

  • VUID-VkSubpassDependency-srcSubpass-00865
    srcSubpass and dstSubpass must not both be equal to VK_SUBPASS_EXTERNAL

  • VUID-VkSubpassDependency-srcSubpass-00867
    If srcSubpass is equal to dstSubpass and not all of the stages in srcStageMask and dstStageMask are framebuffer-space stages, the logically latest pipeline stage in srcStageMask must be logically earlier than or equal to the logically earliest pipeline stage in dstStageMask

  • VUID-VkSubpassDependency-srcAccessMask-00868
    Any access flag included in srcAccessMask must be supported by one of the pipeline stages in srcStageMask, as specified in the table of supported access types

  • VUID-VkSubpassDependency-dstAccessMask-00869
    Any access flag included in dstAccessMask must be supported by one of the pipeline stages in dstStageMask, as specified in the table of supported access types

  • VUID-VkSubpassDependency-srcSubpass-02243
    If srcSubpass equals dstSubpass, and srcStageMask and dstStageMask both include a framebuffer-space stage, then dependencyFlags must include VK_DEPENDENCY_BY_REGION_BIT

  • VUID-VkSubpassDependency-dependencyFlags-02520
    If dependencyFlags includes VK_DEPENDENCY_VIEW_LOCAL_BIT, srcSubpass must not be equal to VK_SUBPASS_EXTERNAL

  • VUID-VkSubpassDependency-dependencyFlags-02521
    If dependencyFlags includes VK_DEPENDENCY_VIEW_LOCAL_BIT, dstSubpass must not be equal to VK_SUBPASS_EXTERNAL

  • VUID-VkSubpassDependency-srcSubpass-00872
    If srcSubpass equals dstSubpass and that subpass has more than one bit set in the view mask, then dependencyFlags must include VK_DEPENDENCY_VIEW_LOCAL_BIT

  • VUID-VkSubpassDependency-srcStageMask-02099
    If the mesh shaders feature is not enabled, srcStageMask must not contain VK_PIPELINE_STAGE_MESH_SHADER_BIT_NV

  • VUID-VkSubpassDependency-srcStageMask-02100
    If the task shaders feature is not enabled, srcStageMask must not contain VK_PIPELINE_STAGE_TASK_SHADER_BIT_NV

  • VUID-VkSubpassDependency-dstStageMask-02101
    If the mesh shaders feature is not enabled, dstStageMask must not contain VK_PIPELINE_STAGE_MESH_SHADER_BIT_NV

  • VUID-VkSubpassDependency-dstStageMask-02102
    If the task shaders feature is not enabled, dstStageMask must not contain VK_PIPELINE_STAGE_TASK_SHADER_BIT_NV

Valid Usage (Implicit)
  • VUID-VkSubpassDependency-srcStageMask-parameter
    srcStageMask must be a valid combination of VkPipelineStageFlagBits values

  • VUID-VkSubpassDependency-srcStageMask-requiredbitmask
    srcStageMask must not be 0

  • VUID-VkSubpassDependency-dstStageMask-parameter
    dstStageMask must be a valid combination of VkPipelineStageFlagBits values

  • VUID-VkSubpassDependency-dstStageMask-requiredbitmask
    dstStageMask must not be 0

  • VUID-VkSubpassDependency-srcAccessMask-parameter
    srcAccessMask must be a valid combination of VkAccessFlagBits values

  • VUID-VkSubpassDependency-dstAccessMask-parameter
    dstAccessMask must be a valid combination of VkAccessFlagBits values

  • VUID-VkSubpassDependency-dependencyFlags-parameter
    dependencyFlags must be a valid combination of VkDependencyFlagBits values

See Also

Document Notes

For more information, see the Vulkan Specification

This page is extracted from the Vulkan Specification. Fixes and changes should be made to the Specification, not directly.

Copyright (c) 2014-2020 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0