llvm-project

05c0db7f - [TableGen] Emit the primary input file in -d depfile output (#197061)

[TableGen] Emit the primary input file in -d depfile output (#197061) This fixes a bug where old, but still supported, versions of CMake and ninja perpetually consider zero-include tablegen files to be out of date. It also matches what Clang and GCC do for regular C compilations. When a .td input has no `include` directives, the depfile produced by `-d` contains only `<output>:` followed by zero dependencies. My version (3.27) of CMake's `cmake_transform_depfile` step then writes a 0-byte file, which old versions of ninja treat as a missing depfile and re-run the rule on every incremental build (e.g. Attributes.td, ValueTypes.td). Here's the effect on Attributes.inc.d: ``` $ cat ./build/include/llvm/IR/Attributes.inc.d Attributes.inc: # switch branches and rebuild... $ cat ./build/include/llvm/IR/Attributes.inc.d Attributes.inc: /work/llvm-project/llvm/include/llvm/IR/Attributes.td ``` An LLM was used to help create this change.