Re: [PATCH] target/sh4: add missing CHECK_NOT_DELAY_SLOT

[Yoshinori Sato]

On Mon, 08 Apr 2024 00:07:05 +0900,
Zack Buhman wrote:
> 
> CHECK_NOT_DELAY_SLOT is correctly applied to the branch-related
> instructions, but not to the PC-relative mov* instructions.
> 
> I verified the existence of an illegal slot exception on a SH7091 when
> any of these instructions are attempted inside a delay slot.
> 
> This also matches the behavior described in the SH-4 ISA manual.
> 
> Signed-off-by: Zack Buhman <zack@buhman.org>
> ---
>  target/sh4/translate.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/target/sh4/translate.c b/target/sh4/translate.c
> index 6643c14dde..ebb6c901bf 100644
> --- a/target/sh4/translate.c
> +++ b/target/sh4/translate.c
> @@ -523,6 +523,7 @@ static void _decode_opc(DisasContext * ctx)
>          tcg_gen_movi_i32(REG(B11_8), B7_0s);
>          return;
>      case 0x9000: /* mov.w @(disp,PC),Rn */
> +        CHECK_NOT_DELAY_SLOT
>          {
>              TCGv addr = tcg_constant_i32(ctx->base.pc_next + 4 + B7_0 * 2);
>              tcg_gen_qemu_ld_i32(REG(B11_8), addr, ctx->memidx,
> @@ -530,6 +531,7 @@ static void _decode_opc(DisasContext * ctx)
>          }
>          return;
>      case 0xd000: /* mov.l @(disp,PC),Rn */
> +        CHECK_NOT_DELAY_SLOT
>          {
>              TCGv addr = tcg_constant_i32((ctx->base.pc_next + 4 + B7_0 * 4) 
> & ~3);
>              tcg_gen_qemu_ld_i32(REG(B11_8), addr, ctx->memidx,
> @@ -1236,6 +1238,7 @@ static void _decode_opc(DisasContext * ctx)
>          }
>          return;
>      case 0xc700: /* mova @(disp,PC),R0 */
> +        CHECK_NOT_DELAY_SLOT
>          tcg_gen_movi_i32(REG(0), ((ctx->base.pc_next & 0xfffffffc) +
>                                    4 + B7_0 * 4) & ~3);
>          return;
> -- 
> 2.41.0
>

That's what the documentation said.
> If a PC-relative load instruction is executed in a delay slot,
> an illegal slot instruction exception will be generated.

Reviewed-by: Yoshinori Sato <ysato@users.sourceforge.jp>

-- 
Yosinori Sato