diff mbox series

[4/6] accel/tcg: Improve setting of can_do_io at start of TB

Message ID 20230914174436.1597356-5-richard.henderson@linaro.org
State Superseded
Headers show
Series accel/tcg: Always require can_do_io (#1866) | expand

Commit Message

Richard Henderson Sept. 14, 2023, 5:44 p.m. UTC 
Initialize can_do_io to true if this the TB has CF_LAST_IO
and will consist of a single instruction.  This avoids a
set to 0 followed immediately by a set to 1.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 accel/tcg/translator.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Philippe Mathieu-Daudé Sept. 15, 2023, 9:47 a.m. UTC | #1 
On 14/9/23 19:44, Richard Henderson wrote:
> Initialize can_do_io to true if this the TB has CF_LAST_IO
> and will consist of a single instruction.  This avoids a
> set to 0 followed immediately by a set to 1.
> 
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>   accel/tcg/translator.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
diff mbox series

Patch

diff --git a/accel/tcg/translator.c b/accel/tcg/translator.c
index 850d82e26f..dd507cd471 100644
--- a/accel/tcg/translator.c
+++ b/accel/tcg/translator.c
@@ -87,12 +87,12 @@  static TCGOp *gen_tb_start(DisasContextBase *db, uint32_t cflags)
                          offsetof(ArchCPU, neg.icount_decr.u16.low) -
                          offsetof(ArchCPU, env));
         /*
-         * cpu->can_do_io is cleared automatically here at the beginning of
+         * cpu->can_do_io is set automatically here at the beginning of
          * each translation block.  The cost is minimal and only paid for
          * -icount, plus it would be very easy to forget doing it in the
          * translator.
          */
-        set_can_do_io(db, false);
+        set_can_do_io(db, db->max_insns == 1 && (cflags & CF_LAST_IO));
     }
 
     return icount_start_insn;