[clang] [llvm] [Clang][OpenMP] Implement Loop splitting `#pragma omp split` directive (PR #183261)

[via cfe-commits]

github-actions[bot] wrote:

<!--PREMERGE ADVISOR COMMENT: Windows-->
# :window: Windows x64 Test Results

* 81953 tests passed
* 2001 tests skipped

All executed tests passed, but another part of the build **failed**. Click on a failure below to see the details.

<details>
<summary>[code=1] tools/clang/lib/CodeGen/CMakeFiles/obj.clangCodeGen.dir/CGStmt.cpp.obj</summary>

```
FAILED: [code=1] tools/clang/lib/CodeGen/CMakeFiles/obj.clangCodeGen.dir/CGStmt.cpp.obj
sccache C:\clang\clang-msvc\bin\clang-cl.exe  /nologo -TP -DCLANG_BUILD_STATIC -DUNICODE -D_CRT_NONSTDC_NO_DEPRECATE -D_CRT_NONSTDC_NO_WARNINGS -D_CRT_SECURE_NO_DEPRECATE -D_CRT_SECURE_NO_WARNINGS -D_GLIBCXX_ASSERTIONS -D_HAS_EXCEPTIONS=0 -D_LIBCPP_HARDENING_MODE=_LIBCPP_HARDENING_MODE_EXTENSIVE -D_SCL_SECURE_NO_DEPRECATE -D_SCL_SECURE_NO_WARNINGS -D_UNICODE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -IC:\_work\llvm-project\llvm-project\build\tools\clang\lib\CodeGen -IC:\_work\llvm-project\llvm-project\clang\lib\CodeGen -IC:\_work\llvm-project\llvm-project\clang\include -IC:\_work\llvm-project\llvm-project\build\tools\clang\include -IC:\_work\llvm-project\llvm-project\build\include -IC:\_work\llvm-project\llvm-project\llvm\include /DWIN32 /D_WINDOWS   /Zc:inline /Zc:__cplusplus /Oi /Brepro /bigobj /permissive- -Werror=unguarded-availability-new /W4  -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wno-pass-failed -Wmisleading-indentation -Wctad-maybe-unsupported /Gw /O2 /Ob2  -std:c++17 -MD -UNDEBUG /EHs-c- /GR- /showIncludes /Fotools\clang\lib\CodeGen\CMakeFiles\obj.clangCodeGen.dir\CGStmt.cpp.obj /Fdtools\clang\lib\CodeGen\CMakeFiles\obj.clangCodeGen.dir\ -c -- C:\_work\llvm-project\llvm-project\clang\lib\CodeGen\CGStmt.cpp
C:\_work\llvm-project\llvm-project\clang\lib\CodeGen\CGStmt.cpp(234,5): error: use of undeclared identifier 'EmitOMPSplitDirective'
234 |     EmitOMPSplitDirective(cast<OMPSplitDirective>(*S));
|     ^~~~~~~~~~~~~~~~~~~~~
1 error generated.
```
</details>

If these failures are unrelated to your changes (for example tests are broken or flaky at HEAD), please open an issue at https://github.com/llvm/llvm-project/issues and add the `infrastructure` label.

https://github.com/llvm/llvm-project/pull/183261