[PATCH] D99620: [CMake][Compiler-rt] Compute LLVM_MAIN_SRC_DIR assuming the monorepo layout.

[Dan Liew via Phabricator via llvm-commits]

delcypher added a comment.

In D99620#2660134 <https://reviews.llvm.org/D99620#2660134>, @delcypher wrote:

> In D99620#2660017 <https://reviews.llvm.org/D99620#2660017>, @tstellar wrote:
>
>> We still build compiler-rt in non-monorepo configuration for Fedora.  Which files from the llvm directory (or other directories in the monorepo) does compiler-rt depend on?
>
> @tstellar Several. This subsequent patch (https://reviews.llvm.org/D99621) might illuminate some of this because it starts the work of trying to remove the dependency on the `LLVMConfig.cmake` file which is generated by an LLVM build but isn't necessarily shipped with toolchains.

@tstellar

To expand on this.

Compiler-rt currently depends on at least the following

- The `LLVMConfig.cmake` file that's generated by the build of LLVM. It's located at `lib/cmake/llvm/LLVMConfig.cmake` in the root of an LLVM build and is optionally installed by toolchain maintainers.
- Several CMake files that lives in the `llvm/cmake/modules` in the llvm source tree. `LLVMConfig.cmake` does `include(${LLVM_CMAKE_DIR}/LLVM-Config.cmake)` where `LLVM_CMAKE_DIR` points at the directory containing this file. For a build directory `LLVM_CMAKE_DIR` points into the llvm source tree, for an installed toolchain `LLVM_CMAKE_DIR` will point to where the files where optionally installed by toolchain maintainers.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D99620/new/

https://reviews.llvm.org/D99620