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dawn / tint / 66e7569e15a627eb4ed1849c9a4fe8bb435c3b15
commit66e7569e15a627eb4ed1849c9a4fe8bb435c3b15[log] [tgz]
authorDavid Neto <dneto@google.com>Mon Dec 20 16:46:55 2021 +0000
committerTint LUCI CQ <tint-scoped@luci-project-accounts.iam.gserviceaccount.com>Mon Dec 20 16:46:55 2021 +0000
treedd1708c2bcb3c03322c185b0bb49e888acb9493a
parenta9d6c34d868affa55c403ce82428882b825441a2 [diff]
spirv-writer: Fix termination of basic blocks

There are a few places where a branch or return is created,
conditionally on whether a terminator was the last thing seen.
The goal is to generate a SPIR-V basic block terminator exactly
when needed, and to avoid generating a branch or return immediately
after a prior terminator.

Previously, the decision was based on the last thing seen in the AST.
But we should instead check the emitted SPIR-V instead.

This fixes cases such as a break or return inside an else-if.
That's because an if/elseif is actually a selection inside a selection.
Looking at the AST only works when trying to terminate the *inside*
selection.  In the outer recursive call, the last AST node is
no longer a terminator, and we would skip generating the branch
to the merge block.

Fixed: tint:1315
Change-Id: I6b886ce85d1d681f2063997e469e0c1b4e5973a2
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/73480
Kokoro: Kokoro <noreply+kokoro@google.com>
Auto-Submit: David Neto <dneto@google.com>
Reviewed-by: James Price <jrprice@google.com>
Commit-Queue: James Price <jrprice@google.com>
4 files changed
tree: dd1708c2bcb3c03322c185b0bb49e888acb9493a
  1. .vscode/
  2. build_overrides/
  3. docs/
  4. fuzzers/
  5. include/
  6. infra/
  7. kokoro/
  8. samples/
  9. src/
  10. test/
  11. third_party/
  12. tools/
  13. .clang-format
  14. .gitignore
  15. .gn
  16. AUTHORS
  17. BUILD.gn
  18. CMakeLists.txt
  19. CMakeSettings.json
  20. CODE_OF_CONDUCT.md
  21. CONTRIBUTING.md
  22. CPPLINT.cfg
  23. DEPS
  24. Doxyfile
  25. LICENSE
  26. OWNERS
  27. PRESUBMIT.py
  28. README.md
  29. standalone.gclient
  30. tint_overrides_with_defaults.gni
README.md

Tint

Tint is a compiler for the WebGPU Shader Language (WGSL).

This is not an officially supported Google product.

Requirements

  • Git
  • CMake (3.10.2 or later)
  • Ninja (or other build tool)
  • Python, for fetching dependencies
  • depot_tools in your path

Build options

  • TINT_BUILD_SPV_READER : enable the SPIR-V input reader (off by default)
  • TINT_BUILD_WGSL_READER : enable the WGSL input reader (on by default)
  • TINT_BUILD_SPV_WRITER : enable the SPIR-V output writer (on by default)
  • TINT_BUILD_WGSL_WRITER : enable the WGSL output writer (on by default)
  • TINT_BUILD_FUZZERS : enable building fuzzzers (off by default)

Building

Tint uses Chromium dependency management so you need to install depot_tools and add it to your PATH.

Getting source & dependencies

# Clone the repo as "tint"
git clone https://dawn.googlesource.com/tint tint
cd tint

# Bootstrap the gclient configuration
cp standalone.gclient .gclient

# Fetch external dependencies and toolchains with gclient
gclient sync

Compiling using CMake + Ninja

mkdir -p out/Debug
cd out/Debug
cmake -GNinja ../..
ninja # or autoninja

Compiling using CMake + make

mkdir -p out/Debug
cd out/Debug
cmake ../..
make # -j N for N-way parallel build

Compiling using gn + ninja

mkdir -p out/Debug
gn gen out/Debug
autoninja -C out/Debug

Fuzzers on MacOS

If you are attempting fuzz, using TINT_BUILD_FUZZERS=ON, the version of llvm in the XCode SDK does not have the needed libfuzzer functionality included.

The build error that you will see from using the XCode SDK will look something like this:

ld: file not found:/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/11.0.0/lib/darwin/libclang_rt.fuzzer_osx.a

The solution to this problem is to use a full version llvm, like what you would get via homebrew, brew install llvm, and use something like CC=<path to full clang> cmake .. to setup a build using that toolchain.

Checking [chromium-style] issues in CMake builds

The gn based work flow uses the Chromium toolchain for building in anticipation of integration of Tint into Chromium based projects. This toolchain has additional plugins for checking for style issues, which are marked with [chromium-style] in log messages. This means that this toolchain is more strict then the default clang toolchain.

In the future we will have a CQ that will build this work flow and flag issues automatically. Until that is in place, to avoid causing breakages you can run the [chromium-style] checks using the CMake based work flows. This requires setting CC to the version of clang checked out by gclient sync and setting the TINT_CHECK_CHROMIUM_STYLE to ON.

mkdir -p out/style
cd out/style
cmake ../..
CC=../../third_party/llvm-build/Release+Asserts/bin/clang cmake -DTINT_CHECK_CHROMIUM_STYLE=ON ../../ # add -GNinja for ninja builds

Issues

Please file any issues or feature requests at https://bugs.chromium.org/p/tint/issues/entry

Contributing

Please see the CONTRIBUTING and CODE_OF_CONDUCT files on how to contribute to Tint.

Tint has a process for supporting experimental extensions.