On 25 Jul 2013, at 16:10, m...@freebsd.org wrote: > Isn't that a compiler bug? memset(p, 0, n) is the same as bzero(p, n). Why > would the compiler warn on one and not the other?
They are different. memcpy is defined by the C standard. bzero is defined by POSIX. When you are compiling C code, the compiler is free to assume behaviour of any C standard functions but not of POSIX functions because it does not know that you are compiling for a POSIX target (possibly it should do this if the relevant POSIX macros are set). As Bruce says, however, the C standard excludes memset() and memcpy() in freestanding environments (which is a shame, because a lot of optimisations depend on their existence, and something I had thought was fixed in C11), so this is not relevant in the kernel. > Does clang have a similar bias for memcpy versus bcopy? Almost certainly. David
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