================ @@ -1073,6 +1073,28 @@ inputs. Here is some example of ``$``-prefixed options: Language and Target-Independent Features ======================================== +Freestanding Builds +------------------- +Passing the ``-ffreestanding`` flag causes Clang to build for a freestanding +(rather than a hosted) environment. The flag has the following effects: + +* the ``__STDC_HOSTED__`` predefined macro will expand to ``0``, +* builtin functions are disabled (``-fno-builtins``), +* unwind tables are disabled (``fno-asynchronous-unwind-tables -fno-unwind-tables``), and +* allows ``main`` to be used as a regular symbol. + +A freestanding environment is not one which has no C standard library support. ---------------- jyknight wrote:
OK, I find the wording now a bit unclear because the new paragraph discusses standards conformance, in the middle of discussing Clang's expectations. I think those two concepts need to clearly distinguished. How about rewording something like: ``` An implementation of the following runtime library functions must always be provided with the usual semantics, as Clang will generate calls to them: * `memcpy`, * `memmove`, and * `memset`. Clang does not, by itself, provide a full "conforming freestanding implementation". If you wish to have a conforming freestanding implementation, you must provide a freestanding C library. While Clang provides some of the required header files, it does not provide all of them, nor any library implementations. Conversely, when `-ffreestanding` is specified, Clang does not _require_ you to provide a conforming freestanding implementation library. Clang will not make any assumptions as to the availability or semantics of standard-library, functions other than those mentioned above. ``` https://github.com/llvm/llvm-project/pull/132232 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
