They aren't guaranteed renderable in Vulkan nor core OpenGL 4.5 without
extensions. They happened to work on a lot of our CQ builders but failed
on Intel OpenGL Linux which helped understand this was an issue.
BUG=dawn:128
Change-Id: I83c4f8116c1125c3bac2f1dd6197976c9063e129
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/9682
Commit-Queue: Austin Eng <enga@chromium.org>
Reviewed-by: Jiawei Shao <jiawei.shao@intel.com>
Reviewed-by: Austin Eng <enga@chromium.org>
This patch refactors the current implementation of BC formats to treat
it as the first extension in Dawn and adds all the related tests.
Note that in Dawn all the extensions are disabled unless we enable them
when we create the device, which means the BC formats can only be used
when we enable the related extension on the creation of the device, and
the creation of the device will fail if the adapter does not support the
extension
BUG=dawn:42
TEST=dawn_end2end_tests
TEST=dawn_unittests
Change-Id: I04d818b0218ebb3b1b7a70a4fea71779f308f85f
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/9520
Commit-Queue: Jiawei Shao <jiawei.shao@intel.com>
Reviewed-by: Austin Eng <enga@chromium.org>
In a typical graphics application it is a common usage to update some uniforms once per draw,
and such uniforms include the word positions, orientations, and so on. In the current state of
WebGPU, this means that for each draw call we have to create a new bind group to set the right
uniform values. Bind group creation is expected to be more expensive than
recording draws because a memory allocation is required.
The functionality of dynamic buffer offset is to reduce the number of bind groups that need to
be created.
The patch implements dynamic buffer offset on D3D backend using root descriptor.
Bug=dawn:55
Change-Id: Ia713a4edb3c0ab8f3bba048d7813f343e9dee166
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/9040
Commit-Queue: Shaobo Yan <shaobo.yan@intel.com>
Reviewed-by: Austin Eng <enga@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Introduces the buddy system for fast power-of-two sub-allocation.
BUG=dawn:27
Change-Id: I56836ae317ecc5a91d8341c843fc37d4f91fb5af
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/9260
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
bindgroup->GetLayout() was called before checking the bindgroup is an
error, causing an assert to fire in Debug. Adds a regression unittest.
BUG=dawn:196
Change-Id: I58e95879a7f2a7cf5c47c7b228f7e3b5bb72d8ea
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/9560
Commit-Queue: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>
In a typical graphics application it is a common usage to update some uniforms once per draw,
and such uniforms include the word positions, orientations, and so on. In the current state of
WebGPU, this means that for each draw call we have to create a new bind group to set the right
uniform values. Bind group creation is expected to be more expensive than
recording draws because a memory allocation is required.
The functionality of dynamic buffer offset is to reduce the number of bind groups that need to
be created.
The patch implements dynamic buffer offset on OpenGL backend using glBindBufferRange and adds
validation to check whether visibility of resources are none.
Bug=dawn:55
Change-Id: I77e10a9677d1737f377301ee89e29d904c91c298
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/9540
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Shaobo Yan <shaobo.yan@intel.com>
This patch factors the CommandAllocator, CommandIterator, and error
handling out of CommandEncoderBase so it can later be used by the
RenderBundleEncoder.
Bug: dawn:154
Change-Id: Ia4f8c3ce7f432f0887b619bd8090aa9bec7330fc
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/9181
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Commit-Queue: Austin Eng <enga@chromium.org>
This CL tests integration of the MemoryTransferService with buffer mapping.
It tests the basic success and error cases for buffer mapping, and it tests
mocked failures of each fallible MemoryTransferService method that an embedder
could implement.
Change-Id: Iece660fb49664cc6a09a0b0b8dbe59e2882a6017
Bug: dawn:156
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/8841
Commit-Queue: Austin Eng <enga@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
This patch adds MemoryTransfer client/server interfaces and
uses it to implement data transfers for buffer mapping.
This patch also provides a default "inline" implementation of
the MemoryTransfer which is used if the embedder does not
provide one on initialization.
Because implementations of MemoryTransfer perform their own
serialization, a skip_serialize option is added to WireCmd records.
Bug: dawn:156
Change-Id: I2fa035517628a3ad465b0bc18a6ffc477e2bd67f
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/8642
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Austin Eng <enga@chromium.org>
This is needed for two reasons:
- TextureBase and TextureViewBase stored Formats by value which isn't too
much overhead at this time but will get bigger in the future.
- The OpenGL backends needs its own GLFormat structure to store data about
each format which will eventually contain complicated logic to detect
support in the GL driver so it shouldn't be duplicated in Textures.
The computations of the information about Format is moved from being done
whenever they are needed to being precomputed at DeviceBase initialization.
This makes each format have a constant "index" in that can be used in the
backends to address their own structure, for example a GLFormat table.
Also some DeviceBase pointers were made const for validation.
BUG=dawn:128
Change-Id: I37d1e9c739b87cddcea09cb1759e175704d90f9e
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/9101
Reviewed-by: Austin Eng <enga@chromium.org>
Reviewed-by: Jiawei Shao <jiawei.shao@intel.com>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
The existing implementation of Result with tagged pointers was not able
to handle constant pointers for the result. This is required in
follow-up CLs to return internal formats in a ResultOrError.
This CL extracts the tagged pointer logic out of Result<T*, E*> so it
can be shared with Result<const T*, E*>.
Tests are also added to cover Result<const T*, E*>.
BUG=dawn:128
Change-Id: Id19ae8e1153bcfcaf94d95ac314faf2b23af6f91
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/9100
Commit-Queue: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Following WebGPU spec change at https://github.com/gpuweb/gpuweb/issues/331,
bind groups in Dawn now use the whole size of the buffer if binding buffer
size is UINT64_MAX.
Bug: dawn:22
Change-Id: If28d905e634432755dad5c67c69eadedcee53dfe
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/8863
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: François Beaufort <beaufort.francois@gmail.com>
These additions to dawn.json don't require changes to users of the C++
API so they are done now to prepare for webgpu.h. Validation is added
that forbids using the new enum values and non-default values for
members until they are implemented.
BUG=dawn:22
Change-Id: Ie6f3384243d6874e7aca4b94733409755a066c93
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/8862
Reviewed-by: Austin Eng <enga@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Commit-Queue: Kai Ninomiya <kainino@chromium.org>
Previously validation of the combination of dynamic with the binding
type was only done when creating the bind group when it should have been
done when the bind group layout is created.
BUG=dawn:55
Change-Id: I976f7e052f9737929fc05908af50e6ad5ceef397
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/8861
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Instead it is replaced by one enum in dawn_native and another in utils.
BUG=dawn:22
Change-Id: I094a40c8d4e22b704e59aea60cbefd1f05c5352a
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/8800
Commit-Queue: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
This also adds the extra validation needed to support non-renderable
formats, as well as tests for it
BUG=dawn:128
Change-Id: I3bc79b641aa0fd5e3358f89a87f2e457d0ecc58a
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/8760
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Jiawei Shao <jiawei.shao@intel.com>
These are the CommandEncoder, ComputePass and CommandBuffer descriptors
that contains nothing but a debug name for now but are important for
later extensibility. Defaults are added so the C++ API doesn't require
the descriptors to be passed as arguments.
Also renames variables named "info" for RenderPassDescriptor to
"descriptor" as is now the standard in the codebase.
BUG=dawn:22
Change-Id: I9de4cfbbce952d01fb79ed1d9f34825a6fa174f9
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/8686
Reviewed-by: Austin Eng <enga@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Commit-Queue: Kai Ninomiya <kainino@chromium.org>
WebGPU remove dynamic-uniform-buffer and dynamic-storage-buffer but add a new attribute in
BindgroupLayoutBinding to record whether a buffer resource is dynamic.
Dawn need to align with this change.
BUG=dawn:180
Change-Id: I873ad2ec75575e72d184f89a6e3698dff6df50d7
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/8520
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
This is to match the equivalent rename in WebGPU's IDL.
BUG=dawn:22
Change-Id: Ibdf75869e58835d984df559878b884c55310a403
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/8623
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Yunchao He <yunchao.he@intel.com>
This is to match the name in the WeBGPU IDL.
BUG=dawn:22
Change-Id: I0a4a7b62afa30cfd699d90efb2dd0c085778883b
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/8624
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Yunchao He <yunchao.he@intel.com>
This is to match the WebGPU IDL.
BUG=dawn:22
Change-Id: I63e32fe980c1727562055221ea2769a670461e93
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/8625
Reviewed-by: Yunchao He <yunchao.he@intel.com>
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
This patch adds the support of BC5 formats on D3D12 backend. On D3D12,
the "rowPitch" refers to the number of bytes in a row of blocks (which
covers up to 4 scanlines at once) for the textures in BC formats.
This patch also adds the related end2end tests for four typical cases of
B2T and T2B copies on D3D12:
(1) copyBytesPerRowPitch + byteOffsetPerRowPitch <= rowPitch and
texelOffset.y == 0
(2) copyBytesPerRowPitch + byteOffsetPerRowPitch <= rowPitch and
texelOffset.y > 0
(3) copyBytesPerRowPitch + byteOffsetPerRowPitch > rowPitch
(4) texelOffset.z > 0
BUG=dawn:42
TEST=dawn_end2end_tests
Change-Id: If27ab3e56596e25c1c5be787ca021c0748021a46
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/8541
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
The root causes of these failures are as follows:
1. 'fragmentStoresAndAtomics' feature is not enabled when we create the Vulkan device.
2. The binding value of dynamic buffer offset end2end test not set correctly.
For failure reason 1, this patch enabled fragmentStoresAndAtomics.
For failure reason 2, this patch modify dawn validation logic in SetBindGroup to check
binding size and update binding size in dynamic buffer offset end2end test.
BUG=dawn:170
Change-Id: I46f12453d4c83d9d3c7de6e183442cf516335f2f
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/8320
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
This patch implements RenderPassEncoder::SetViewport. It also adds
validation code, and validation tests as well.
BUG=dawn:53
TEST=dawn_unittests
Change-Id: Idc27f4098761a57fc10e53be82bd3c4b35b53cb4
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/8542
Commit-Queue: Yunchao He <yunchao.he@intel.com>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
This adds the formats to dawn.json, implements support in the Vulkan
backend and adds tests performing basic sampling checks for all formats.
The R8UnormSrgb and RG8UnormSrgb formats skipped because they are not
required in Vulkan (and RG8UnormSrgb is in fact not supported on the
machine used for developing this CL). A PR will be sent to the WebGPU
repo to remove the from the initial list of formats.
The RG11B10Float and RGB10A2Unorm formats of WebGPU are replaced with
B10GR11Float and A2RGB10Unorm that are the formats exposed by Vulkan. It
is likely that all APIs implement them with components stored in that
order.
Each format except depth-stencil ones is tested by uploading some
interesting texel data and checking that sampling from the texture
produces correct results. The goal is to make sure that backends don't
make a mistake in the giant switch statements. There was no effort made
to check the hardware implementation of the formats.
Tests will later be extended to cover rendering and clearing operations
as well as multisample resolve.
It isn't clear if depth-stencil format will support TRANSFER operations
in WebGPU so these are left untested for now.
BUG=dawn:128
Change-Id: I78ac5bf77b57398155551e6db3de50b478d69452
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/8363
Reviewed-by: Austin Eng <enga@chromium.org>
Reviewed-by: Jiawei Shao <jiawei.shao@intel.com>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
This will be used to test NaN is correctly sampled from float16
textures.
BUG=dawn:128
Change-Id: I6e3b79f438e9a48c3a167ab45baf9f9d019ce48b
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/8361
Commit-Queue: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>
The width and height of the mipmaps level > 0 weren't computed
correctly. Size of mip level of a texture should be greater than
0.
BUG=dawn:176
TEST=dawn_unittests --gtest_filter=CopyCommandTest*.CopyNonSquareTexture
Change-Id: I730aef3fd8c036567f824cd707d1ea1a69b132c0
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/8242
Commit-Queue: Yizhou Jiang <yizhou.jiang@intel.com>
Reviewed-by: Austin Eng <enga@chromium.org>
This patch adds the validation on the texture copies with BC formats.
1. BufferCopyView.offset in B2T and T2B copies must be a multiple of the
compressed texel block size in bytes.
2. BufferCopyView.rowPitch in B2T and T2B copies refers to the number of
bytes from the start of one row of blocks to the start of the next
row of blocks.
3. BufferCopyView.imageHeight must be a multiple of the compressed texel
block height (4 for BC formats).
4. All members in TextureCopyView.origin must be a multiple of the
corresponding dimensions of the compressed texel block (4x4x1 for BC
formats).
5. All the mumbers in 'copySize' must be a multiple of the corresponding
dimensions of the compressed texel block (4x4x1 for BC formats)
because D3D12 requires the width and height of a texture in BC
formats must be multiples of 4.
6. Compute the texture size in non-zero mipmap levels with paddings for
textures in BC formats when necessary.
BUG=dawn:42
TEST=dawn_unittests
Change-Id: Iac8d6c93ab8b37bb46becffd4175339722ab6016
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/7860
Commit-Queue: Jiawei Shao <jiawei.shao@intel.com>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
This patch fixes a bug in the computation of texture copy buffer size.
As the 'width' and 'height' in copy commands are all in pixels, while
the buffer size is counted in bytes, we shoud first convert 'width' into
bytes before calculating the buffer size.
BUG=dawn:42
TEST=dawn_unittests
Change-Id: Iebd5ed07a54eea762f4a653e295ecacb845ba32f
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/7940
Commit-Queue: Jiawei Shao <jiawei.shao@intel.com>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
This prevents dirty textures to be used when memory is recycled
while destroying/creating textures. If a texture is not cleared at load,
it will be cleared to 0 before it is used.
Bug: dawn:145
Change-Id: Ia3f02427478fb48649089829186ccb377caa1912
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/6960
Commit-Queue: Natasha Lee <natlee@microsoft.com>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
This is a reland of 7eb6be186be60a536a9f529b514bb5c5fd79293d
Fixes casting issue on 32 bit machines
Original change's description:
> dawn_native: Indirect draw/dispatch
>
> Adds indirect draw and dispatch for all backends (without validation).
>
> Tests for opengl negative offset are skipped since there is no easy
> way to add the index buffer offset. Current idea is to use a compute
> shader to modify the indirect draw buffer.
>
> Change-Id: I1d3eec7c699b211423f4b911769cca17bfbcd045
> Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/7481
> Commit-Queue: Idan Raiter <idanr@google.com>
> Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Change-Id: Id28c5658ee18ec5c030f721fb44d9f11ebe21ff9
Bug:dawn:54,chromium:972358
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/7961
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Commit-Queue: Idan Raiter <idanr@google.com>
This reverts commit 7eb6be186be60a536a9f529b514bb5c5fd79293d.
Reason for revert: This change is breaking Clusterfuzz bots. crbug.com/972358
Bug: chromium:972358
Original change's description:
> dawn_native: Indirect draw/dispatch
>
> Adds indirect draw and dispatch for all backends (without validation).
>
> Tests for opengl negative offset are skipped since there is no easy
> way to add the index buffer offset. Current idea is to use a compute
> shader to modify the indirect draw buffer.
>
> Change-Id: I1d3eec7c699b211423f4b911769cca17bfbcd045
> Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/7481
> Commit-Queue: Idan Raiter <idanr@google.com>
> Reviewed-by: Kai Ninomiya <kainino@chromium.org>
TBR=cwallez@chromium.org,kainino@chromium.org,idanr@google.com
# Not skipping CQ checks because original CL landed > 1 day ago.
Change-Id: I9b7b63de0900e20c4da8561ceb9b2dece77c3885
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/7960
Commit-Queue: Austin Eng <enga@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>
Adds indirect draw and dispatch for all backends (without validation).
Tests for opengl negative offset are skipped since there is no easy
way to add the index buffer offset. Current idea is to use a compute
shader to modify the indirect draw buffer.
Change-Id: I1d3eec7c699b211423f4b911769cca17bfbcd045
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/7481
Commit-Queue: Idan Raiter <idanr@google.com>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Also adds a test that would have fired the ASSERT.
BUG=dawn:80
BUG=dawn:107
Change-Id: I56cdbc91956465c8941b45bb5e9da4c27da301ae
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/7840
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Yunchao He <yunchao.he@intel.com>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
This requires some changes in the wire because WireCmd doesn't know the
size of void. This also adds a handwritten implementation of the Wire
commands for SetSubData that internally converts to uint8_t so that
WireCmd can generate the de/serialization.
BUG=dawn:160
Change-Id: Icbf0fd7dd841639ee6f67333844e027b27a8afcc
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/7780
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
This patch changed the front end code and tests and examples.
BUG=dawn:80, dawn:107
Change-Id: Ia6c60232c04a1bfb862263766eb28e9afc3bc8db
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/7620
Commit-Queue: Yunchao He <yunchao.he@intel.com>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
This uses an intermediate staging buffer to copy data into the buffer.
Bug: dawn:7
Change-Id: I3bda19a8450ef0eddc5b4382ce1b9120f074b917
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/7500
Commit-Queue: Austin Eng <enga@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
This patch adds all the BC compressed texture formats and the checks on
the creation of textures in BC formats. If a texture is in BC format,
then:
1. The width and height of the texture must be multiple of 4.
2. The usage of the texture can only be Sampled or TransferSrc or
TransferDst.
3. The sample count of the texture can only be 1.
BUG=dawn:42
TEST=dawn_unittests
Change-Id: I0844fb6a1aadbb96d94a61fd969db07c21b6adf5
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/7600
Commit-Queue: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
This initial reasoning for having a u64 userdata was to be able to pack
two u32s in a single userdata but that was never used, and made a bunch
of code uglier than it should.
BUG=dawn:160
Change-Id: Ia0d20bc23f09f5d8f3748ca4edd1a331604f2ba8
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/7561
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
This is only a renaming: change VertexInput to VertexBuffer, and
change InputState to VertexInput.
The next two patches will do as follows:
1) change the structure of vertex input descriptor related stuff.
2) change num to count.
BUG=dawn:80, dawn:107
Change-Id: Ie76aa653a527759a9c3b4a4792e3254689f053b8
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/7420
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Commit-Queue: Yunchao He <yunchao.he@intel.com>
