[llvm-dev] llvm intrinsics/libc/libm question

Tim Northover via llvm-dev llvm-dev at lists.llvm.org
Tue Jun 7 13:38:41 PDT 2016

On 7 June 2016 at 13:24, Ryan Taylor via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> Not sure why it's called TargetLibraryInfo if it's not in target specific
> code? It seems that ALL targets use this code, making it generic. Am I
> missing something here?

Some of the names can vary by platform, for example ARM sometimes has
__aeabi_memcpy instead of memcpy

> ps. The spec also states (albeit unclearly) that you can use "#undef" to
> omit a library function so that a user defined function of the same name can
> be used but LLVM doesn't seem to support that.

I think it says exactly the opposite: (7.1.2p3):

    "If the program removes (with #undef) any macro definition of an
identifier in the first group listed above, the behavior is

Incidentally, I don't think anyone's mentioned that "-ffreestanding"
will probably inhibit the intrinsics substantially if that's what
you're after (technically, it's probably a compiler extension that it
gives them back to the user, but everyone does it as far as I know).



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