Good morning everyone,
We are changing build-script to use the LLVM-recommended way to build compiler-rt, since the current way will be removed in LLVM-21 1 2 3 -- we are planning for this transition to be as seamless as possible, but regardless we want to share how we are planning to carry this out:
- add the new logic but keep it disabled for now
- users can opt into this by specifying
--llvm-build-compiler-rt-with-use-runtimesto build-script - this is tackled by build-script: Permit to build compiler-rt with `LLVM_ENABLE_RUNTIMES` by edymtt · Pull Request #80174 · swiftlang/swift · GitHub
- users can opt into this by specifying
- test the enablement with PR testing and toolchain builds
- we already done a first pass at this in Use LLVM_USE_RUNTIMES to build compiler-rt by default by edymtt · Pull Request #80253 · swiftlang/swift · GitHub
- enable the new logic by default, and assess any fallout in CI
- we are keeping the old logic, so that affected configurations can temporarily revert to that using
--llvm-build-compiler-rt-with-use-runtimes=0while we fix the underlying issues
- we are keeping the old logic, so that affected configurations can temporarily revert to that using
- after all regressions are tackled, remove the old logic together with the flag
We are currently aiming at landing the new logic disabled in the next week or two to allow time for feedback; shortly after this, we will start testing the enablement; we will then schedule the enablement by default depending on how many fixes the new logic needs.