forked from OSchip/llvm-project
8e3e56f2a3
Summary: Although using `__builtin_shufflevector` and the `shufflevector` instruction works fine, they are not opaque to the optimizer. As a result, DAGCombine can potentially reduce the number of shuffles and change the shuffle masks. This is unexpected behavior for users of the WebAssembly SIMD intrinsics who have crafted their shuffles to optimize the code generated by engines. This patch solves the problem by adding a new shuffle intrinsic that is opaque to the optimizers in line with the decision of the WebAssembly SIMD contributors at https://github.com/WebAssembly/simd/issues/196#issuecomment-622494748. In the future we may implement custom DAG combines to properly optimize shuffles and replace this solution. Reviewers: aheejin, dschuff Subscribers: sbc100, jgravelle-google, hiraditya, sunfish, cfe-commits, llvm-commits Tags: #clang, #llvm Differential Revision: https://reviews.llvm.org/D66983 |
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| INPUTS | ||
| bindings | ||
| cmake | ||
| docs | ||
| examples | ||
| include | ||
| lib | ||
| runtime | ||
| test | ||
| tools | ||
| unittests | ||
| utils | ||
| www | ||
| .clang-format | ||
| .clang-tidy | ||
| .gitignore | ||
| CMakeLists.txt | ||
| CODE_OWNERS.TXT | ||
| INSTALL.txt | ||
| LICENSE.TXT | ||
| ModuleInfo.txt | ||
| NOTES.txt | ||
| README.txt | ||
README.txt
//===----------------------------------------------------------------------===// // C Language Family Front-end //===----------------------------------------------------------------------===// Welcome to Clang. This is a compiler front-end for the C family of languages (C, C++, Objective-C, and Objective-C++) which is built as part of the LLVM compiler infrastructure project. Unlike many other compiler frontends, Clang is useful for a number of things beyond just compiling code: we intend for Clang to be host to a number of different source-level tools. One example of this is the Clang Static Analyzer. If you're interested in more (including how to build Clang) it is best to read the relevant web sites. Here are some pointers: Information on Clang: http://clang.llvm.org/ Building and using Clang: http://clang.llvm.org/get_started.html Clang Static Analyzer: http://clang-analyzer.llvm.org/ Information on the LLVM project: http://llvm.org/ If you have questions or comments about Clang, a great place to discuss them is on the Clang development mailing list: http://lists.llvm.org/mailman/listinfo/cfe-dev If you find a bug in Clang, please file it in the LLVM bug tracker: http://llvm.org/bugs/