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    SubjectRe: [PATCH] C undefined behavior fix
    On Wed, Jan 02, 2002 at 12:13:34PM -0800, Joe Buck wrote:
    >
    > > 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.

    If we go with this, it also might make sense to split all of the
    {PTR,UN,}RELOC() macro users into a different file or split up btext.c a
    bit more, just to be safe.

    > 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).

    Well, it's one of those changes that really should stop gcc, unless
    there's a bug on the gcc side, if I read the patch/comments about it
    right.

    --
    Tom Rini (TR1265)
    http://gate.crashing.org/~trini/
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