Speed up indirect branches by adding a helper to look for the
TB in tb_jmp_cache. The helper returns either the corresponding
host address or NULL.
Measurements:
- Impact on Boot time
| setup | ARM debian boot+shutdown time | stddev |
|---------+-------------------------------+--------|
| master | 10.050247057 | 0.0361 |
| +cross | 10.311265443 | 0.0721 |
| +jr | 10.216832579 | 0.0878 |
| +inline | 10.405597879 | 0.0332 |
That is, a 3.5% slowdown. This is reasonable since booting
has low hit rates in tb_jmp_cache.
- NBench, arm-linux-user. Host: Intel i7-4790K @ 4.00GHz
Y axis: speedup over 95b31d70
1.25x+-+-------------------------------------------------------------+-+
| jr $$$ |
| jr+inline %%% |
1.2x+-+..................................$$$%%......................+-+
| $ $ % |
| $ $ % |
| %%% $ $ % %% |
1.15x+-+........................%.%.......$.$.%.$$$%.................+-+
| % % $ $ % $ $% |
| $$$ % $ $ % $ $% |
1.1x+-+......................$.$.%.......$.$.%.$.$%.................+-+
| $ $ % $ $ % $ $% |
| $ $ % $$$ $ $ % $ $% %%% |
1.05x+-+......................$.$.%.$.$%%.$.$.%.$.$%.............$$$.%-+
| $$$%% $$%% $ $ % $ $ % $ $ % $ $% $ $ % |
| $$$%% $ $ % $$ % $ $ % $ $ % $ $ % $ $% $ $ % |
| $ $ % $ $ % $$ % $ $ % $ $ % $ $ % $ $% %%% $$$%% $ $ % |
1x+-$.$B%R$$$%%G$A$H%T$$P%j$+$n%i$e$.%.$.$.%.$.$%.$$$.%.$.$.%.$.$.%-+
+-$$$%%-$$$%%-$$$%%-$$%%-$$$%%-$$$%%-$$$%%-$$$%-$$$%%-$$$%%-$$$%%-+
ASSIGNMBITFIELFOFP_EMULATHUFFMANLU_DECOMPNEURNUMERICSTRING_SOhmean
png: http://imgur.com/ihqQj6l
That is, a 6.65% hmean improvement with jr+inline (5.92% w/o inlining).
Peak improvement is 21% for HUFFMAN.
- NBench, arm-softmmu. Host: Intel i7-4790K @ 4.00GHz
Y axis: speedup over 95b31d70
+------------------------------------------------------------------+
| |
1.3x+-+........................................ cross+noinline $$ +-+
| cross+inline %% |
| && @@&& cross+jr+noinline @@ |
| $$%@& @@ & cross+jr+inline && |
1.2x+-+.................$$%@&......$$..&&..@@.&......................+-+
| $$%@& $$%%@& @@ & @@& |
| $$%@& $$ %@& @@ & @@& |
1.1x+-+.................$$%@&...@@.$$.%@&..@@.&..@@&................&&-+
| $$%@& $$%@& @@&$$ %@& @@ & @@& @@& |
| $$%@& $$%@& @@&$$ %@&$$%@ & @@& $$%@& $$%@& |
| $$%&& $$%&& $$%@& $$%@&$$$%@&$$ %@&$$%@ & %%@& $$%@& $$%@& |
1x+-$$%@&A$$%@&A$$%@&A$$%@&$R$%@&$$T%@&$$%@s&+%%@&n$$%@&.$$%@&.$$%@&-+
| $$%@& $$%@& $$%@& $$%@&$ $%@&$$ %@&$$%@ & %%@& $$%@& $$%@& $$%@& |
| $$%@& $$%@& $$%@& $$%@&$ $%@&$$ %@&$$%@ & %%@& $$%@& $$%@& $$%@& |
0.9x+-$$%@&.$$%@&.$$%@&.$$%@&$.$%@&$$.%@&$$%@.&.%%@&.$$%@&.$$%@&.$$%@&-+
| $$%@& $$%@& $$%@& $$%@&$ $%@&$$ %@&$$%@ & %%@& $$%@& $$%@& $$%@& |
| $$%@& $$%@& $$%@& $$%@&$ $%@&$$ %@&$$%@ &$$%@& $$%@& $$%@& $$%@& |
| $$%@& $$%@& $$%@& $$%@&$ $%@&$$ %@&$$%@ &$$%@& $$%@& $$%@& $$%@& |
0.8x+-$$%@&-$$%@&-$$%@&-$$%@&$$$%@&$$%%@&$$%@&&$$%@&-$$%@&-$$%@&-$$%@&-+
ASSIGNMBITFIELFOUFP_EMULATHUFFMALU_DECOMPNEURANUMERICSTRING_SOhmean
png: http://imgur.com/yWJivBl
That is, a 9.86% hmean improvement when combining cross+jr+inline (this commit)
over current master. Peak improvement is 25% for FP_EMULATION.
Signed-off-by: Emilio G. Cota <c...@braap.org>
---
target/arm/helper.c | 11 +++++++++++
target/arm/helper.h | 1 +
target/arm/translate.c | 23 +++++++++++++++++++++++
3 files changed, 35 insertions(+)
diff --git a/target/arm/helper.c b/target/arm/helper.c
index 10b8807..dfbc488 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -9927,3 +9927,14 @@ uint32_t HELPER(cross_page_check)(CPUARMState *env,
target_ulong vaddr)
{
return !!tb_from_jmp_cache(env, vaddr);
}
+
+void *HELPER(get_hostptr)(CPUARMState *env, target_ulong vaddr)
+{
+ TranslationBlock *tb;
+
+ tb = tb_from_jmp_cache(env, vaddr);
+ if (unlikely(tb == NULL)) {
+ return NULL;
+ }
+ return tb->tc_ptr;
+}
diff --git a/target/arm/helper.h b/target/arm/helper.h
index d4b779b..0faacc1 100644
--- a/target/arm/helper.h
+++ b/target/arm/helper.h
@@ -2,6 +2,7 @@ DEF_HELPER_FLAGS_1(sxtb16, TCG_CALL_NO_RWG_SE, i32, i32)
DEF_HELPER_FLAGS_1(uxtb16, TCG_CALL_NO_RWG_SE, i32, i32)
DEF_HELPER_2(cross_page_check, i32, env, tl)
+DEF_HELPER_2(get_hostptr, ptr, env, tl)
DEF_HELPER_3(add_setq, i32, env, i32, i32)
DEF_HELPER_3(add_saturate, i32, env, i32, i32)
diff --git a/target/arm/translate.c b/target/arm/translate.c
index ce97d0c..2510bb2 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -65,6 +65,14 @@ static TCGv_i32 cpu_R[16];
TCGv_i32 cpu_CF, cpu_NF, cpu_VF, cpu_ZF;
TCGv_i64 cpu_exclusive_addr;
TCGv_i64 cpu_exclusive_val;
+static bool gen_jr;
+
+static inline void set_jr(void)
+{
+ if (TCG_TARGET_HAS_jr) {
+ gen_jr = true;
+ }
+}
/* FIXME: These should be removed. */
static TCGv_i32 cpu_F0s, cpu_F1s;
@@ -221,6 +229,7 @@ static void store_reg(DisasContext *s, int reg, TCGv_i32
var)
*/
tcg_gen_andi_i32(var, var, s->thumb ? ~1 : ~3);
s->is_jmp = DISAS_JUMP;
+ set_jr();
}
tcg_gen_mov_i32(cpu_R[reg], var);
tcg_temp_free_i32(var);
@@ -893,6 +902,7 @@ static inline void gen_bx_im(DisasContext *s, uint32_t addr)
tcg_temp_free_i32(tmp);
}
tcg_gen_movi_i32(cpu_R[15], addr & ~1);
+ set_jr();
}
/* Set PC and Thumb state from var. var is marked as dead. */
@@ -902,6 +912,7 @@ static inline void gen_bx(DisasContext *s, TCGv_i32 var)
tcg_gen_andi_i32(cpu_R[15], var, ~1);
tcg_gen_andi_i32(var, var, 1);
store_cpu_field(var, thumb);
+ set_jr();
}
/* Variant of store_reg which uses branch&exchange logic when storing
@@ -12042,6 +12053,18 @@ void gen_intermediate_code(CPUARMState *env,
TranslationBlock *tb)
gen_set_pc_im(dc, dc->pc);
/* fall through */
case DISAS_JUMP:
+ if (TCG_TARGET_HAS_jr && gen_jr) {
+ TCGv_ptr ptr = tcg_temp_local_new_ptr();
+ TCGLabel *label = gen_new_label();
+
+ gen_jr = false;
+ gen_helper_get_hostptr(ptr, cpu_env, cpu_R[15]);
+ tcg_gen_brcondi_ptr(TCG_COND_EQ, ptr, NULL, label);
+ tcg_gen_jr(ptr);
+ tcg_temp_free_ptr(ptr);
+ gen_set_label(label);
+ /* fall through */
+ }
default:
/* indicate that the hash table must be used to find the next TB */
tcg_gen_exit_tb(0);
--
2.7.4
