Re: [PATCH] C undefined behavior fix

Joe Buck
2002-01-02T20:14:04Z

> Okay, here's a summary of all of the options we have:
> 1) Change this particular strcpy to a memcpy
> 2) Add -ffreestanding to the CFLAGS of arch/ppc/kernel/prom.o (If this
> optimization comes back on with this flag later on, it would be a
> compiler bug, yes?)
> 3) Modify the RELOC() marco in such a way that GCC won't attempt to
> optimize anything which touches it [1]. (Franz, again by Jakub)
> 4) Introduce a function to do the calculations [2]. (Corey Minyard)
> 5) 'Properly' set things up so that we don't need the RELOC() macros
> (-mrelocatable or so?), and forget this mess altogether.

2) will prevent any future gcc from ever assuming it can transform the
strcpy into anything but a call to strcpy, or assume anything about the
semantics of strcpy. Be careful with 3), as trying to fool the optimizer
is likely to be only a temporary solution (meaning that the kernel people
will return to flame the gcc people when the optimizer gets changed
again).