Re: [Qemu-devel] [PATCH v2 for-2.5 05/12] tcg/optimize: track const/copy status separately

[Paolo Bonzini]

On 27/07/2015 12:56, Aurelien Jarno wrote:
>          temps[dst].next_copy = temps[src].next_copy;
>          temps[dst].prev_copy = src;
>          temps[temps[dst].next_copy].prev_copy = dst;
>          temps[src].next_copy = dst;

This is:

    dst->next = src->next;
    dst->prev = src;
    dst->next->prev = dst;
    src->next = dst;

which seems weird.  I think it should be one of

    /* splice src after dst */
    dst->next->prev = src->prev;
    src->prev->next = dst->next;
    dst->next = src;
    src->prev = dst;

or

    /* splice src before dst */
    last = src->prev;
    dst->prev->next = src;
    src->prev = dst->prev;
    last->next = dst;
    dst->prev = last;

(written as pointer manipulations for clarity).

Maybe I'm missing the obvious, but if it's a problem it's better to fix
it before the links are used more pervasively.

Paolo