| Message ID | 20230628114504.546265-3-mark.cave-ayland@ilande.co.uk |
|---|---|
| State | Accepted |
| Commit | f67ccb2f77190e597562b2041b36ee7d9f6f302b |
| Headers | show |
| Series | None | expand |
On Wed, 28 Jun 2023, Mark Cave-Ayland wrote: > From: Richard Henderson <richard.henderson@linaro.org> > > Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> > Signed-off-by: Richard Henderson <richard.henderson@linaro.org> > Message-Id: <20230628071202.230991-2-richard.henderson@linaro.org> > Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk> > --- > target/sparc/translate.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/target/sparc/translate.c b/target/sparc/translate.c > index bad2ec90a0..28d4cdb8b4 100644 > --- a/target/sparc/translate.c > +++ b/target/sparc/translate.c > @@ -318,10 +318,10 @@ static void gen_goto_tb(DisasContext *s, int tb_num, > tcg_gen_movi_tl(cpu_npc, npc); > tcg_gen_exit_tb(s->base.tb, tb_num); > } else { > - /* jump to another page: currently not optimized */ > + /* jump to another page: we can use an indirect jump */ > tcg_gen_movi_tl(cpu_pc, pc); > tcg_gen_movi_tl(cpu_npc, npc); > - tcg_gen_exit_tb(NULL, 0); > + tcg_gen_lookup_and_goto_ptr(); Out of curiosity, did you test this is actually faster? The reason I ask is because I've tried to optimise similar case in target/ppc by using lookup_and_goto_ptr but found it was slower than without that. I think this may depend on the usage but I wonder if that could be a generic issue with lookup_and_goto_ptr or only specific for the case I've tried. Regards, BALATON Zoltan > } > } > >
On 6/28/23 15:00, BALATON Zoltan wrote: > On Wed, 28 Jun 2023, Mark Cave-Ayland wrote: >> From: Richard Henderson <richard.henderson@linaro.org> >> >> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> >> Signed-off-by: Richard Henderson <richard.henderson@linaro.org> >> Message-Id: <20230628071202.230991-2-richard.henderson@linaro.org> >> Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk> >> --- >> target/sparc/translate.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/target/sparc/translate.c b/target/sparc/translate.c >> index bad2ec90a0..28d4cdb8b4 100644 >> --- a/target/sparc/translate.c >> +++ b/target/sparc/translate.c >> @@ -318,10 +318,10 @@ static void gen_goto_tb(DisasContext *s, int tb_num, >> tcg_gen_movi_tl(cpu_npc, npc); >> tcg_gen_exit_tb(s->base.tb, tb_num); >> } else { >> - /* jump to another page: currently not optimized */ >> + /* jump to another page: we can use an indirect jump */ >> tcg_gen_movi_tl(cpu_pc, pc); >> tcg_gen_movi_tl(cpu_npc, npc); >> - tcg_gen_exit_tb(NULL, 0); >> + tcg_gen_lookup_and_goto_ptr(); > > Out of curiosity, did you test this is actually faster? The reason I ask is because I've > tried to optimise similar case in target/ppc by using lookup_and_goto_ptr but found it was > slower than without that. I think this may depend on the usage but I wonder if that could > be a generic issue with lookup_and_goto_ptr or only specific for the case I've tried. It is faster. It should be *always* faster, because returning to the main cpu loop will always do more work than merely checking to see if we already have built the required TB. If you see slowdowns, then *probably* you are using lookup_and_goto_ptr incorrectly in some instance, such that an interrupt has gotten overly delayed. (One must always return to the main loop after anything that might re-enable interrupts. Otherwise the interrupt handler may be delayed indefinitely. This was in fact the problem with v1 of this patch set.) r~
diff --git a/target/sparc/translate.c b/target/sparc/translate.c index bad2ec90a0..28d4cdb8b4 100644 --- a/target/sparc/translate.c +++ b/target/sparc/translate.c @@ -318,10 +318,10 @@ static void gen_goto_tb(DisasContext *s, int tb_num, tcg_gen_movi_tl(cpu_npc, npc); tcg_gen_exit_tb(s->base.tb, tb_num); } else { - /* jump to another page: currently not optimized */ + /* jump to another page: we can use an indirect jump */ tcg_gen_movi_tl(cpu_pc, pc); tcg_gen_movi_tl(cpu_npc, npc); - tcg_gen_exit_tb(NULL, 0); + tcg_gen_lookup_and_goto_ptr(); } }