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    SubjectRe: [PATCH] lib/string.c: Disable tree-loop-distribute-patterns
    On Tue, Aug 18, 2020 at 05:44:03PM -0700, Linus Torvalds wrote:
    > On Tue, Aug 18, 2020 at 4:43 PM Arvind Sankar <nivedita@alum.mit.edu> wrote:
    > >
    > > This by itself is insufficient for gcc if the optimization was
    > > explicitly enabled by CFLAGS, so also add a flag to explicitly disable
    > > it.
    >
    > Using -fno-tree-loop-distribute-patterns seems to really be a bit too
    > incestuous with internal compiler knowledge.

    Fair enough -- you ok with just the -ffreestanding? That's what protects
    the memset in arch/x86/boot/compressed/string.c.

    I think this is worthwhile to be safe.

    >
    > That generic memcpy implementation is horrible anyway. It should never be used.
    >
    > So I'd rather see this either removed entirely, ot possibly rewritten
    > to be a somewhat proper memcpy implementation, and in the process made
    > to not be recognizable by the compiler (possibly by adding a dummy
    > barrier() or something like that).
    >
    > Looking at the implementation of "strscpy()" in the same file, and
    > then comparing that to the ludicrously simplisting "memcpy()", I
    > really get the feeling that that memcpy() is not worth having.
    >
    > Linus

    I don't think anything actually uses the generic memcpy, and I think
    only c6x uses the generic memset. Might be worth optimizing strnlen etc
    with the word-at-a-time thing though.

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