[all-commits] [llvm/llvm-project] f9dbca: [CMake] Enable LLVM_ENABLE_PER_TARGET_RUNTIME_DIR ...

[Fangrui Song via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: f9dbca68d48e705f6d45df8f58d6b2ee88bce76c
      https://github.com/llvm/llvm-project/commit/f9dbca68d48e705f6d45df8f58d6b2ee88bce76c
  Author: Fangrui Song <i at maskray.me>
  Date:   2021-09-15 (Wed, 15 Sep 2021)

  Changed paths:
    M llvm/CMakeLists.txt

  Log Message:
  -----------
  [CMake] Enable LLVM_ENABLE_PER_TARGET_RUNTIME_DIR by default on Linux

This makes the default build closer to a -DLLVM_ENABLE_RUNTIMES=all build.
The layout is arguably superior because different libraries of target triples
are in different directories, similar to GCC/Debian multiarch.

When LLVM_DEFAULT_TARGET_TRIPLE is x86_64-unknown-linux-gnu,
`lib/clang/14.0.0/lib/libclang_rt.asan-x86_64.a`
is moved to
`lib/clang/14.0.0/lib/x86_64-unknown-linux-gnu/libclang_rt.asan.a`.

In addition, if the host compiler supports -m32 (multilib),
`lib/clang/14.0.0/lib/libclang_rt.asan-i386.a`
is moved to
`lib/clang/14.0.0/lib/i386-unknown-linux-gnu/libclang_rt.asan.a`.

Clang has been detecting both paths for lib/Driver/ToolChains/Gnu.cpp since 2018 (D50547).

---

Note: Darwin needs to be disabled. The hierarchy needs to be sorted out.
The current -DLLVM_DEFAULT_TARGET_TRIPLE=off state is like:
```
lib/clang/14.0.0/lib/darwin/libclang_rt.profile_ios.a
lib/clang/14.0.0/lib/darwin/libclang_rt.profile_iossim.a
lib/clang/14.0.0/lib/darwin/libclang_rt.profile_osx.a
```

Windows needs to be disabled: https://reviews.llvm.org/D107799?id=368557#2963311

Differential Revision: https://reviews.llvm.org/D107799