memcpy overlap: quickly detect, diagnose, work around

[Kevin Kofler]

John Reiser wrote:
> Right.  However, specifying the flag -fno-builtin-memcpy at compilation
> disables gcc inlining of memcpy

But not glibc's.

You need -D__NO_STRING_INLINES too. (That said, the most aggressive inlining 
is disabled by default and only enabled if you use -D__USE_STRING_INLINES.)

In any case, it means you need to recompile the executables, not just drop 
in the modified glibc.

        Kevin Kofler