https://gcc.gnu.org/bugzilla/show_bug.cgi?id=32667
Rich Felker <bugdal at aerifal dot cx> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |bugdal at aerifal dot cx
--- Comment #24 from Rich Felker <bugdal at aerifal dot cx> ---
If the copy is such that gcc is happy to emit an external call to memcpy for
it, there is no significant size or performance cost to emitting a branch
checking for equality before making the call, and performing this branch would
greatly optimize the (maybe rare in the caller, maybe not) case of
self-assignment!
On the other hand, expecting the libc memcpy to make this check greatly
pessimizes every reasonable small use of memcpy with a gratuitous branch for
what is undefined behavior and should never appear in any valid program.
Fix it on the compiler side please.
