commit 7eca355b81049a6c405e7111ea074b51aadc3b25
author Corentin Wallez <cwallez@chromium.org> Thu Aug 21 23:55:49 2025 -0700
committer Dawn LUCI CQ <dawn-scoped@luci-project-accounts.iam.gserviceaccount.com> Thu Aug 21 23:55:49 2025 -0700
tree b3f722dcb150acb831433a28125e4b8d7a9a75ed
parent 4e9e28f05f3b2f99bea0f4ded046e0b11d02bc6b

[dawn][vk] Implement dynamic array BGLs

In Vulkan the equivalent concept to dynamic binding arrays are
descriptor arrays with all the VK_KHR_descriptor_indexing flags
enabled. The allocation strategy for the VkDescriptorSet needs to change
as the sets may have varying size even if used on the same layout. This
in turns requires a different, simpler version of the
DescriptorSetAllocator to be used.

In order to minimize the amount of additional branching that happens
because of the bindless path (which is cold, but static-only bindgroups
are perf critical), BindGroupLayoutVk is split into two subclasses that
dispatch to the regular DescriptorSetAllocator or a new
DescriptorSetAllocatorDynamicArray. (I tried 4 different approaches and
the current one seems to be the less disgusting one)

Changes in this CL are:

 - Remove logic in DescriptorSetAllocator to handle pool sizes of 0 as
   this is no longer a Vulkan error to do, and VVLs don't complain
   anymore.
 - Add DescriptorSetAllocatorDynamicArray that creates descriptor sets
   with variable counts and doesn't do any recycling or suballocation of
   the underlying VkDescriptorPool (apps should create few dynamic array
   bindgroups).
 - Split vulkan::BindGroupLayout into a base class and a child class for
   StaticBindingOnly.
 - Factor out the code that computes information related to static
   bindings into its own function.
 - Add a BindGroupLayoutDynamicArray that creates a
   VkDescriptorSetLayout with a variable count and uses
   DescriptorSetAllocatorDynamicArray.
 - In BindGroupLayoutInternalBase, decide that the dynamic array will
   directly follow the static bindings, and have separate getters that
   return either a BindingNumber or a BindingIndex.

This change can barely be tested on its own, but end2end tests with
BindGroup dynamic array creation in follow up CLs found a bunch of bugs
and will provide coverage.

Bug: 439522242
Change-Id: Ia24227aed66831caa4cb8d3bfe1407ed420fdca2
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/257774
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>