Support mappedAtCreation for SharedBufferMemory buffers

SharedBufferMemory::CreateBuffer did not call MapAtCreation() when the
descriptor had mappedAtCreation=true, causing GetMappedRange() to return
nullptr after BeginAccess.

Fix by:
- Calling MapAtCreation() in SharedBufferMemoryBase::CreateBuffer when
  mappedAtCreation is set.
- Adding mIsMappedAtCreation to BufferBase, set in
  MapAtCreationInternal() and cleared in Unmap(), so that
  OnBeginAccess() restores MappedAtCreation state (instead of always
  Unmapped) when BeginAccess is called on a still-mapped buffer.
- Making BufferBase::GetState() public so BeginAccess can detect the
  MappedAtCreation state and skip SetInitialized(descriptor->initialized),
  preserving the initialized=true already set by MapAtCreation() and
  preventing lazy-clear from zeroing user-written data on the first GPU
  read.

Bug: 386255678
Change-Id: Ic719265f6e291d95297d498690eacf4c0c6192ca
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/320815
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Shao, Jiawei <jiawei.shao@intel.com>
5 files changed
tree: 79f34e9777e42d90aeab3002e5c708ed34098050
  1. .github/
  2. .vscode/
  3. agents/
  4. build_overrides/
  5. docs/
  6. generator/
  7. include/
  8. infra/
  9. scripts/
  10. src/
  11. test/
  12. third_party/
  13. tools/
  14. webgpu-cts/
  15. .bazelrc
  16. .bazelversion
  17. .clang-format
  18. .clang-format-ignore
  19. .clang-tidy
  20. .git-blame-ignore-revs
  21. .gitattributes
  22. .gitignore
  23. .gitmodules
  24. .gn
  25. .style.yapf
  26. .vpython3
  27. AUTHORS
  28. BUILD.bazel
  29. BUILD.gn
  30. CMakeLists.txt
  31. CMakeSettings.json
  32. CODE_OF_CONDUCT.md
  33. codereview.settings
  34. CONTRIBUTING.md
  35. CPPLINT.cfg
  36. DEPS
  37. DIR_METADATA
  38. go.mod
  39. go.sum
  40. go_presubmit_support.py
  41. LICENSE
  42. MODULE.bazel
  43. MODULE.bazel.lock
  44. OWNERS
  45. PRESUBMIT.py
  46. PRESUBMIT_test.py
  47. README.chromium
  48. README.md
  49. unsafe_buffers_paths.txt
  50. WATCHLISTS
  51. WORKSPACE.bazel
README.md

Build Status Matrix Space

Dawn, a WebGPU implementation

Dawn is an open-source and cross-platform implementation of the WebGPU standard. More precisely it implements webgpu.h that is a one-to-one mapping with the WebGPU IDL. Dawn is meant to be integrated as part of a larger system and is the underlying implementation of WebGPU in Chromium.

Dawn provides several WebGPU building blocks:

  • WebGPU C/C++ headers that applications and other building blocks use.
    • The webgpu.h version that Dawn implements.
    • A C++ wrapper for the webgpu.h.
  • A “native” implementation of WebGPU using platforms' GPU APIs: D3D12, Metal, Vulkan and OpenGL. See per API support for more details.
  • A client-server implementation of WebGPU for applications that are in a sandbox without access to native drivers
  • Tint is a compiler for the WebGPU Shader Language (WGSL) that can be used in standalone to convert shaders from and to WGSL.

Helpful links:

Documentation table of content

Developer documentation:

User documentation: (TODO, figure out what overlaps with the webgpu.h docs)

License

BSD 3-Clause License, please see LICENSE.

Disclaimer

This is not an officially supported Google product.