On Mon, 19 Aug 2019 at 22:38, Richard Henderson
<[email protected]> wrote:
>
> Convert the register shifted by immediate form of the data
> processing insns. For A32, we cannot yet remove any code
> because the legacy decoder intertwines the reg-shifted-reg
> and immediate forms.
>
> Signed-off-by: Richard Henderson <[email protected]>
> ---
> target/arm/translate.c | 229 ++++++++++++++++++++++++++++++++++-------
> target/arm/a32.decode | 28 +++++
> target/arm/t32.decode | 43 ++++++++
> 3 files changed, 264 insertions(+), 36 deletions(-)
> +#define DO_ANY3(NAME, OP, L, K) \
> + static bool trans_##NAME##_rrri(DisasContext *s, arg_s_rrr_shi *a) \
> + { StoreRegKind k = (K); return op_s_rrr_shi(s, a, OP, L, k); }
It's a bit non-obvious that we can return early via the expression K
here (for the "trying to do an old-style exception return in usermode"
case for SUB and MOV), but it does put the check early where we need it.
> +DO_ANY3(SUB, a->s ? gen_sub_CC : tcg_gen_sub_i32, false,
> + ({
> + StoreRegKind ret = STREG_NORMAL;
> + if (a->rd == 15 && a->s) {
> + /*
> + * See ALUExceptionReturn:
> + * In User mode, UNPREDICTABLE; we choose UNDEF.
> + * In Hyp mode, UNDEFINED.
> + */
> + if (IS_USER(s) || s->current_el == 2) {
> + return false;
> + }
> + /* There is no writeback of nzcv to PSTATE. */
> + a->s = 0;
> + ret = STREG_EXC_RET;
> + } else if (a->rd == 13 && a->rn == 13) {
> + ret = STREG_SP_CHECK;
> + }
> + ret;
> + }))
It turns out that the decode for Thumb means that we don't
need to specifically check that this is Arm mode before allowing
the ALUExceptionReturn handling.
Reviewed-by: Peter Maydell <[email protected]>
thanks
-- PMM
