On Fri, Nov 15, 2019 at 6:03 AM Peter Maydell <[email protected]>
wrote:
> Richard, I think we're tripping over the check you added
> in commit af2882289951e. Specifically:
>
> + /* We UNDEF for these UNPREDICTABLE cases. */
> + if (a->rd == 15 || a->rn == 15 || a->rt == 15
> + || a->rd == a->rn || a->rd == a->rt
> + || (s->thumb && (a->rd == 13 || a->rt == 13))
> + || (mop == MO_64
> + && (a->rt2 == 15
> + || a->rd == a->rt2 || a->rt == a->rt2
> + || (s->thumb && a->rt2 == 13)))) {
> + unallocated_encoding(s);
> + return true;
> + }
>
> in the mop == MO_64 subclause we check for
> a->rt == a->rt2
> so we will UNDEF for rt == rt2, as in this example. But the
> pseudocode in the spec doesn't say that rt == rt2 is
> an UNPREDICTABLE case. (It is an UNDPREDICTABLE
> case for LDREXD, but STREXD lets you write the same
> register twice if you want to.) Or am I misreading this?
>
BTW, I can confirm that removing the check "a->rt == a->rt2" seems to fix
my problem.
