llvm-project

2a906318 - [mlir][spirv] Allow yielding values from selection regions (#133702)

[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.