efriedma added inline comments.
================ Comment at: flang/runtime/CMakeLists.txt:251 - INSTALL_WITH_TOOLCHAIN -) +if (DEFINED LLVM_ENABLE_RUNTIMES AND "flang-rt" IN_LIST LLVM_ENABLE_RUNTIMES) + add_flang_library(FortranRuntime STATIC ---------------- pscoro wrote: > efriedma wrote: > > pscoro wrote: > > > efriedma wrote: > > > > This "if" doesn't make sense to me. If we're not building flang-rt, we > > > > shouldn't be here, so I don't see why you need an "if" in the first > > > > place. > > > `add_subdirectory(runtime)` is a line that still exists in > > > `flang/CMakeLists.txt`. This exists because `Fortran_main` is still being > > > built at the same time as the compiler, and to do so, the runtime > > > subdirectory still needs to be added to flang (`flang/CMakeLists.txt` -> > > > `add_subdirectory(runtime)` -> `flang/runtime/CMakeLists.txt` -> > > > `add_subdirectory(FortranMain)`. The solution I had was to just add a > > > check around the `FortranRuntime` library production so that it only > > > happens for flang-rt. > > > > > > If you have a better solution let me know. Overall, I'm not sure if > > > Fortran_main is currently being handled in the best way (ie, its still > > > being built at the same time as the compiler, which doesn't seem ideal), > > > but am not sure what course of action to take with it since it doesn't > > > really belong in flang-rt either (see documentation for details) > > Fortran_main should be "part of" flang-rt in the sense that building > > flang-rt builds it. Most of the same reasons we want to build flang-rt.a > > as a runtime apply. > > > > Since the output needs to be separate, building flang-rt should produce two > > libraries: flang-rt.a and FortranMain.a. > I agree with this idea and have been trying to make it work but in the > process I discovered that my "fix" above (`if (DEFINED LLVM_ENABLE_RUNTIMES > AND "flang-rt" IN_LIST LLVM_ENABLE_RUNTIMES)`) is worse than I thought. > > By building the llvm target with flang-rt as an enabled runtime, we are > essentially saying: build the flang compiler, and then invoke cmake again to > build the runtimes project (externally), which builds flang-rt. > > The problem is that check-all depends on check-flang which depends on the > runtime. The if guard above was not actually doing what I thought it was, and > the reason why configuring didnt fail with "flang-rt does not exist" is > because the if guard was still evaluating to true. Basically, the guard > ensured that FortranRuntime was only being built if flang-rt is built, but > the add_library call was still being reached *during the configuration of the > flang compiler*. > > I am having trouble dealing with this dependency since runtimes get built > externally (and after the compiler is built, which is when the check-all > custom target gets built). I will have to investigate more closely how other > runtimes handle this. My initial thought was perhaps the runtime testing > should be decoupled from check-flang/check-all however I don't know if that's > a good idea, and I also think that only helps with flang-rt, but if > Fortran_main is required to build any executable I imagine that it should be > needed for check-flang? > > This is just an update of whats holding me back right now. If you have any > tips please let me know. Thanks for bringing this to my attention. For comparison, check-clang doesn't require any runtime libraries at all. All the checks only check the generated LLVM IR/driver commands/etc. Any tests that require runtime execution go into either the regression tests for the runtimes themselves, or into lllvm-test-suite. Probably check-flang should do something similar. It probably makes sense to add a check-flang-rt target or something like that. (Not sure which existing flang tests are impacted.) Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D154869/new/ https://reviews.llvm.org/D154869 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
