[PATCH] D86993: Document Clang's expectations of the C standard library.

[John McCall via Phabricator via cfe-commits]

rjmccall added a subscriber: t.p.northover.
rjmccall added a comment.

@t.p.northover says it's complicated.  `memcpy`, `memmove`, `memset`, and `bzero` are (I think) the only ones that LLVM will potentially synthesize from nothing and therefore need to be present even in freestanding builds; that's probably okay for us to guarantee.  That's probably also a good place to document the supported way to write those functions in libraries (just `-fno-builtin`, IIRC?).

In hosted builds, we should document that we assume the existence of the standard C library for the target platform, potentially including non-standard functions like `exp10`.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D86993/new/

https://reviews.llvm.org/D86993