[mlir][spirv] Allow yielding values from selection regions (#133702)

There are cases in SPIR-V shaders where values need to be yielded from
the selection region to make valid MLIR. For example (part of the SPIR-V
shader decompiled to GLSL):

```
bool _115
if (_107)
{
    // ...
    float _200 = fma(...);
    // ...
    _115 = _200 < _174;
}
else
{
    _115 = _107;
}
bool _123;
if (_115)
{
    // ...
    float _213 = fma(...);
    // ...
    _123 = _213 < _174;
}
else
{
    _123 = _115;
}
````

This patch extends `mlir.selection` so it can return values.
`mlir.merge` is used as a "yield" operation. This allows to maintain a
compatibility with code that does not yield any values, as well as, to
maintain an assumption that `mlir.merge` is the only operation in the
merge block of the selection region.
7 files changed
tree: 9f542151b365620dc1b35afc1322b09fa89e9ab0
  1. .ci/
  2. .github/
  3. bolt/
  4. clang/
  5. clang-tools-extra/
  6. cmake/
  7. compiler-rt/
  8. cross-project-tests/
  9. flang/
  10. flang-rt/
  11. libc/
  12. libclc/
  13. libcxx/
  14. libcxxabi/
  15. libunwind/
  16. lld/
  17. lldb/
  18. llvm/
  19. llvm-libgcc/
  20. mlir/
  21. offload/
  22. openmp/
  23. polly/
  24. pstl/
  25. runtimes/
  26. third-party/
  27. utils/
  28. .clang-format
  29. .clang-tidy
  30. .git-blame-ignore-revs
  31. .gitattributes
  32. .gitignore
  33. .mailmap
  34. CODE_OF_CONDUCT.md
  35. CONTRIBUTING.md
  36. LICENSE.TXT
  37. pyproject.toml
  38. README.md
  39. SECURITY.md
README.md

The LLVM Compiler Infrastructure

OpenSSF Scorecard OpenSSF Best Practices libc++

Welcome to the LLVM project!

This repository contains the source code for LLVM, a toolkit for the construction of highly optimized compilers, optimizers, and run-time environments.

The LLVM project has multiple components. The core of the project is itself called “LLVM”. This contains all of the tools, libraries, and header files needed to process intermediate representations and convert them into object files. Tools include an assembler, disassembler, bitcode analyzer, and bitcode optimizer.

C-like languages use the Clang frontend. This component compiles C, C++, Objective-C, and Objective-C++ code into LLVM bitcode -- and from there into object files, using LLVM.

Other components include: the libc++ C++ standard library, the LLD linker, and more.

Getting the Source Code and Building LLVM

Consult the Getting Started with LLVM page for information on building and running LLVM.

For information on how to contribute to the LLVM project, please take a look at the Contributing to LLVM guide.

Getting in touch

Join the LLVM Discourse forums, Discord chat, LLVM Office Hours or Regular sync-ups.

The LLVM project has adopted a code of conduct for participants to all modes of communication within the project.