[PATCH] D79279: Add overloaded versions of builtin mem* functions

[Richard Smith - zygoloid via Phabricator via cfe-commits]

rsmith added a comment.

In D79279#2197176 <https://reviews.llvm.org/D79279#2197176>, @rjmccall wrote:

> I thought part of the point of `__builtin_memcpy` was so that C library headers could do `#define memcpy(x, y, z) __builtin_memcpy(x, y, z)`.  If so, the conformance issue touches `__builtin_memcpy` as well, not just calls to the library builtin.

They would have to declare it as well (because C code can `#undef memcpy` and expect to then be able to call a real function), so the `#define` would be pointless.  It doesn't look like glibc does anything like this; do you know of a C standard library implementation that does?

If we want to follow that path, then we'll presumably (eventually) want address-space-`_overloaded` versions of all lib builtins that take pointers -- looks like that's around 60 functions total. That said, I do wonder how many of the functions in question that we're implicitly overloading on address space actually support such overloading -- certainly any of them that we lower to a call to a library function is going to go wrong at runtime.

+ at tstellar, who added this functionality in r233706 -- what was the intent here?


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