This patch adds icount handling to mfspr/mtspr instructions
that may deal with hardware timers.

Signed-off-by: Pavel Dovgalyuk <pavel.dovgalyuk@ispras.ru>
---
 target/openrisc/translate.c |   15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/target/openrisc/translate.c b/target/openrisc/translate.c
index c6dce879f1..a9c81f8bd5 100644
--- a/target/openrisc/translate.c
+++ b/target/openrisc/translate.c
@@ -884,6 +884,18 @@ static bool trans_l_mfspr(DisasContext *dc, arg_l_mfspr *a)
         gen_illegal_exception(dc);
     } else {
         TCGv spr = tcg_temp_new();
+
+        if (tb_cflags(dc->base.tb) & CF_USE_ICOUNT) {
+            gen_io_start();
+            if (dc->delayed_branch) {
+                tcg_gen_mov_tl(cpu_pc, jmp_pc);
+                tcg_gen_discard_tl(jmp_pc);
+            } else {
+                tcg_gen_movi_tl(cpu_pc, dc->base.pc_next + 4);
+            }
+            dc->base.is_jmp = DISAS_EXIT;
+        }
+
         tcg_gen_ori_tl(spr, cpu_R(dc, a->a), a->k);
         gen_helper_mfspr(cpu_R(dc, a->d), cpu_env, cpu_R(dc, a->d), spr);
         tcg_temp_free(spr);
@@ -898,6 +910,9 @@ static bool trans_l_mtspr(DisasContext *dc, arg_l_mtspr *a)
     } else {
         TCGv spr;
 
+        if (tb_cflags(dc->base.tb) & CF_USE_ICOUNT) {
+            gen_io_start();
+        }
         /* For SR, we will need to exit the TB to recognize the new
          * exception state.  For NPC, in theory this counts as a branch
          * (although the SPR only exists for use by an ICE).  Save all

On 11/5/20 3:54 AM, Pavel Dovgalyuk wrote:
> This patch adds icount handling to mfspr/mtspr instructions
> that may deal with hardware timers.
> 
> Signed-off-by: Pavel Dovgalyuk <pavel.dovgalyuk@ispras.ru>
> ---
>  target/openrisc/translate.c |   15 +++++++++++++++
>  1 file changed, 15 insertions(+)

Looks correct, but it would be better not to duplicate the code from
trans_l_mtspr, and use an is_jmp code (called DISAS_UPDATE_EXIT in some other
targets).


r~

On 06.11.2020 00:39, Richard Henderson wrote:
> On 11/5/20 3:54 AM, Pavel Dovgalyuk wrote:
>> This patch adds icount handling to mfspr/mtspr instructions
>> that may deal with hardware timers.
>>
>> Signed-off-by: Pavel Dovgalyuk <pavel.dovgalyuk@ispras.ru>
>> ---
>>   target/openrisc/translate.c |   15 +++++++++++++++
>>   1 file changed, 15 insertions(+)
> 
> Looks correct, but it would be better not to duplicate the code from
> trans_l_mtspr, and use an is_jmp code (called DISAS_UPDATE_EXIT in some other
> targets).

mtspr includes the following comment:
* Save all of the cpu state first, allowing it to be overwritten.

Does it mean, that helper can overwrite the PC? Then the PC can't be 
updated in is_jmp handler at the end of instruction translation.


Pavel Dovgalyuk