| commit | b1bf623ee5ad028ca9555738b7f4a0f20bed82b4 | [log] [tgz] |
|---|---|---|
| author | Nicolas Capens <capn@google.com> | Tue Aug 30 16:16:38 2022 -0400 |
| committer | Nicolas Capens <nicolascapens@google.com> | Thu Sep 01 19:58:07 2022 +0000 |
| tree | 7207446b179e940e7b5691c44b14ca39855373df | |
| parent | 649b3a7aed7c66f89e5d346d2e8fef73a50c437d [diff] |
Add a reference implementation for frexp() sw::Frexp() currently only works correctly when the CPU treats subnormals as zero. This satisfies the corresponding SPIR-V shader instruction requirements. This change demonstrates a C++ reference implementation of frexp() which also supports subnormal values, in case we have a future need for it. It works by multiplying subnormal values by a power of 2 which makes them normalized. This adds to the value's exponent. The exponent of the normalizing factor is subtracted again when obtaining the exponent of the normalized value. The normalizing factor must larger than or equal to 2^23 for the smallest subnormal value, but must be no larger than 1.0 for the largest non-infinite value to avoid overflow. So it is derived from the lower 7 bits of the input value's exponent. Infinity and NaN are also handled in accordance with the C++ <cmath> specification for std::frexp(). Bug: b/243791551 Change-Id: I68bcfa06379fc858acf8ccf7634cb7812e1dd1cd Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/67868 Kokoro-Result: kokoro <noreply+kokoro@google.com> Tested-by: Nicolas Capens <nicolascapens@google.com> Reviewed-by: Alexis Hétu <sugoi@google.com>
SwiftShader is a high-performance CPU-based implementation of the Vulkan graphics API12. Its goal is to provide hardware independence for advanced 3D graphics.
NOTE: The ANGLE project can be used to achieve a layered implementation of OpenGL ES (aka. “SwANGLE”).
SwiftShader libraries can be built for Windows, Linux, and macOS.
Android and Chrome (OS) build environments are also supported.
CMake
Install CMake for Linux, macOS, or Windows and use either the GUI or run the following terminal commands:
cd build cmake .. cmake --build . --parallel ./vk-unittests
Tip: Set the CMAKE_BUILD_PARALLEL_LEVEL environment variable to control the level of parallelism.
Visual Studio
To build the Vulkan ICD library, use Visual Studio 2019 to open the project folder and wait for it to run CMake. Open the CMake Targets View in the Solution Explorer and select the vk_swiftshader project to build it.
The SwiftShader libraries act as drop-in replacements for graphics drivers.
On Windows, most applications can be made to use SwiftShader's DLLs by placing them in the same folder as the executable. On Linux, the LD_LIBRARY_PATH environment variable or -rpath linker option can be used to direct applications to search for shared libraries in the indicated directory first.
In general, Vulkan applications look for a shared library named vulkan-1.dll on Windows (vulkan-1.so on Linux). This ‘loader’ library then redirects API calls to the actual Installable Client Driver (ICD). SwiftShader's ICD is named libvk_swiftshader.dll, but it can be renamed to vulkan-1.dll to be loaded directly by the application. Alternatively, you can set the VK_ICD_FILENAMES environment variable to the path to vk_swiftshader_icd.json file that is generated under the build directory (e.g. .\SwiftShader\build\Windows\vk_swiftshader_icd.json). To learn more about how Vulkan loading works, read the official documentation here.
See CONTRIBUTING.txt for important contributing requirements.
The canonical repository for SwiftShader is hosted at: https://swiftshader.googlesource.com/SwiftShader.
All changes must be reviewed and approved in the Gerrit review tool at: https://swiftshader-review.googlesource.com. You must sign in to this site with a Google Account before changes can be uploaded.
Next, authenticate your account here: https://swiftshader-review.googlesource.com/new-password (use the same e-mail address as the one configured as the Git commit author).
All changes require a Change-ID tag in the commit message. A commit hook may be used to add this tag automatically, and can be found at: https://gerrit-review.googlesource.com/tools/hooks/commit-msg. You can execute git clone https://swiftshader.googlesource.com/SwiftShader and manually place the commit hook in SwiftShader/.git/hooks/, or to clone the repository and install the commit hook in one go:
git clone https://swiftshader.googlesource.com/SwiftShader && (cd SwiftShader && git submodule update --init --recursive third_party/git-hooks && ./third_party/git-hooks/install_hooks.sh)
On Windows, this command line requires using the Git Bash Shell.
Changes are uploaded to Gerrit by executing:
git push origin HEAD:refs/for/master
When ready, add a project owner as a reviewer on your change.
Some tests will automatically be run against the change. Notably, presubmit.sh verifies the change has been formatted using clang-format 11.0.1. Most IDEs come with clang-format support, but may require upgrading/downgrading to the clang-format version 11.0.0 release version (notably Chromium's buildtools has a clang-format binary which can be an in-between revision which produces different formatting results).
SwiftShader's Vulkan implementation can be tested using the dEQP test suite.
See docs/dEQP.md for details.
The third_party directory contains projects which originated outside of SwiftShader:
subzero contains a fork of the Subzero project. It originates from Google Chrome‘s (Portable) Native Client project. The fork was made using git-subtree to include all of Subzero’s history.
llvm-subzero contains a minimized set of LLVM dependencies of the Subzero project.
PowerVR_SDK contains a subset of the PowerVR Graphics Native SDK for running several sample applications.
googletest contains the Google Test project, as a Git submodule. It is used for running unit tests for Chromium, and Reactor unit tests. Run git submodule update --init to obtain/update the code. Any contributions should be made upstream.
See docs/Index.md.
Public mailing list: swiftshader@googlegroups.com
General bug tracker: https://g.co/swiftshaderbugs
Chrome specific bugs: https://bugs.chromium.org/p/swiftshader
The SwiftShader project is licensed under the Apache License Version 2.0. You can find a copy of it in LICENSE.txt.
Files in the third_party folder are subject to their respective license.
The legal authors for copyright purposes are listed in AUTHORS.txt.
CONTRIBUTORS.txt contains a list of names of individuals who have contributed to SwiftShader. If you‘re not on the list, but you’ve signed the Google CLA and have contributed more than a formatting change, feel free to request to be added.