On Tue, 8 Mar 2022 at 07:20, Richard Henderson
<[email protected]> wrote:
>
> Constrain all references to cpu_R[] to load_gpr and dest_gpr.
> This will be required for supporting shadow register sets.
>
> Signed-off-by: Richard Henderson <[email protected]>
> ---
> target/nios2/translate.c | 144 +++++++++++++++------------------------
> 1 file changed, 55 insertions(+), 89 deletions(-)
> @@ -449,15 +435,11 @@ static void rdctl(DisasContext *dc, uint32_t code,
> uint32_t flags)
> g_assert_not_reached();
> #else
> R_TYPE(instr, code);
> - TCGv t1, t2;
> -
> - if (unlikely(instr.c == R_ZERO)) {
> - return;
> - }
> + TCGv t1, t2, dest = dest_gpr(dc, instr.c);
>
> /* Reserved registers read as zero. */
> if (nios2_cr_reserved(&dc->cr_state[instr.imm5])) {
> - tcg_gen_movi_tl(cpu_R[instr.c], 0);
> + tcg_gen_movi_tl(dest, 0);
> return;
> }
I assume the TCG dead-code elimination will mostly throw away the
write-to-R_ZERO stuff, but here for rdctl I suspect it won't.
But probably real code doesn't do that kind of silly thing.
Reviewed-by: Peter Maydell <[email protected]>
thanks
-- PMM
