[flang-commits] [flang] [flang] Add flag to disable Float128 runtime (PR #110116)

[Slava Zakharin via flang-commits]

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@@ -103,7 +103,13 @@ append(${NO_LTO_FLAGS} CMAKE_CXX_FLAGS)
 add_definitions(-U_GLIBCXX_ASSERTIONS)
 add_definitions(-U_LIBCPP_ENABLE_ASSERTIONS)
 
-add_subdirectory(Float128Math)
+set(FLANG_RUNTIME_ENABLE_F128 On CACHE BOOL
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vzakhari wrote:

Maybe we should use `#if defined(__GLIBC__) && defined(_GNU_SOURCE)` for defining the simple alias for `ynl`.

Regarding adding dependency on the C++ library, I think we want to avoid this for `FortranRuntime`, in general.  When float128 support is enabled via `libc`, the float128 math functions are actually a part of `FortranRuntime` and so using libc++ would break this "rule".

https://github.com/llvm/llvm-project/pull/110116