From: "Emilio G. Cota" <c...@braap.org>
Speed up indirect branches by jumping to the target if it is valid.
Softmmu measurements (see later commit for user-mode results):
Note: baseline (i.e. speedup == 1x) is QEMU v2.9.0.
- Impact on Boot time
| setup | ARM debian jessie boot+shutdown time | stddev |
|--------+--------------------------------------+--------|
| v2.9.0 | 8.84 | 0.07 |
| +cross | 8.85 | 0.03 |
| +jr | 8.83 | 0.06 |
- NBench, arm-softmmu (debian jessie guest). Host:
Intel i7-4790K @ 4.00GHz
1.3x
+-+-------------------------------------------------------------------------------------------------------------+-+
|
|
| cross ####
|
1.25x
+cross+jr..........................................................#++#.........................................+-+
| #### # #
|
| +++# # # #
|
| +++ **** # # #
|
1.2x
+-+...................................####............*..*..#......#..#.........................................+-+
| **** # * * # # #
#### |
| * * # * * # # #
# # |
1.15x
+-+................................*..*..#............*..*..#......#..#.....#..#................................+-+
| * * # * * # # #
# # |
| * * # #### * * # # #
# # |
| * * # # # * * # # #
# # #### |
1.1x
+-+................................*..*..#......#..#..*..*..#......#..#.....#..#.........................#..#...+-+
| * * # # # * * # # #
# # # # |
| * * # # # * * # # #
# # # # |
1.05x
+-+..........................####..*..*..#......#..#..*..*..#......#..#.....#..#......+++............*****..#...+-+
| ***** # * * # # # * * # ***** #
# # +++ | ****### * * # |
| *+++* # * * # # # * * # *+++* #
**** # *****### * * # * * # |
| *****### +++#### * * # * * # ***** # * * # * * #
* * # * | *++# * * # * * # |
1x
+-++-+*+++*-+#++****++#++*+-+*++#+-*++*++#-+*+++*-+#++*++*++#++*+-+*++#+-*++*++#-+*+++*-+#++*++*++#++*+-+*++#+-++-+
| * * # * * # * * # * * # * * # * * # * * #
* * # * * # * * # * * # |
| * * # * * # * * # * * # * * # * * # * * #
* * # * * # * * # * * # |
0.95x
+-+---*****###--****###--*****###--****###--*****###--****###--*****###--****###--*****###--****###--*****###---+-+
ASSIGNMENT BITFIELD FOURFP EMULATION HUFFMAN LU DECOMPOSITIONEURAL
NNUMERIC SOSTRING SORT hmean
png: http://imgur.com/eOLmZNR
NB. 'cross' represents the previous commit.
Signed-off-by: Emilio G. Cota <c...@braap.org>
Message-Id: <1493263764-18657-8-git-send-email-c...@braap.org>
[rth: Replace gen_jr global variable with DISAS_EXIT state.]
Signed-off-by: Richard Henderson <r...@twiddle.net>
---
target/arm/translate.c | 25 ++++++++++++++++---------
target/arm/translate.h | 4 ++++
2 files changed, 20 insertions(+), 9 deletions(-)
diff --git a/target/arm/translate.c b/target/arm/translate.c
index facb52f..f879da6 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -1178,7 +1178,7 @@ static void gen_exception_internal_insn(DisasContext *s,
int offset, int excp)
gen_set_condexec(s);
gen_set_pc_im(s, s->pc - offset);
gen_exception_internal(excp);
- s->is_jmp = DISAS_JUMP;
+ s->is_jmp = DISAS_EXC;
}
static void gen_exception_insn(DisasContext *s, int offset, int excp,
@@ -1187,14 +1187,14 @@ static void gen_exception_insn(DisasContext *s, int
offset, int excp,
gen_set_condexec(s);
gen_set_pc_im(s, s->pc - offset);
gen_exception(excp, syn, target_el);
- s->is_jmp = DISAS_JUMP;
+ s->is_jmp = DISAS_EXC;
}
/* Force a TB lookup after an instruction that changes the CPU state. */
static inline void gen_lookup_tb(DisasContext *s)
{
tcg_gen_movi_i32(cpu_R[15], s->pc & ~1);
- s->is_jmp = DISAS_JUMP;
+ s->is_jmp = DISAS_EXIT;
}
static inline void gen_hlt(DisasContext *s, int imm)
@@ -4146,19 +4146,23 @@ static inline bool use_goto_tb(DisasContext *s,
target_ulong dest)
#endif
}
-static inline void gen_goto_tb(DisasContext *s, int n, target_ulong dest)
+static void gen_goto_ptr(void)
+{
+ TCGv addr = tcg_temp_new();
+ tcg_gen_extu_i32_tl(addr, cpu_R[15]);
+ tcg_gen_lookup_and_goto_ptr(addr);
+ tcg_temp_free(addr);
+}
+
+static void gen_goto_tb(DisasContext *s, int n, target_ulong dest)
{
if (use_goto_tb(s, dest)) {
tcg_gen_goto_tb(n);
gen_set_pc_im(s, dest);
tcg_gen_exit_tb((uintptr_t)s->tb + n);
} else {
- TCGv addr = tcg_temp_new();
-
gen_set_pc_im(s, dest);
- tcg_gen_extu_i32_tl(addr, cpu_R[15]);
- tcg_gen_lookup_and_goto_ptr(addr);
- tcg_temp_free(addr);
+ gen_goto_ptr();
}
}
@@ -12091,11 +12095,14 @@ void gen_intermediate_code(CPUARMState *env,
TranslationBlock *tb)
gen_set_pc_im(dc, dc->pc);
/* fall through */
case DISAS_JUMP:
+ gen_goto_ptr();
+ break;
default:
/* indicate that the hash table must be used to find the next TB */
tcg_gen_exit_tb(0);
break;
case DISAS_TB_JUMP:
+ case DISAS_EXC:
/* nothing more to generate */
break;
case DISAS_WFI:
diff --git a/target/arm/translate.h b/target/arm/translate.h
index 629dab9..93de13f 100644
--- a/target/arm/translate.h
+++ b/target/arm/translate.h
@@ -139,6 +139,10 @@ static void disas_set_insn_syndrome(DisasContext *s,
uint32_t syn)
* custom end-of-TB code)
*/
#define DISAS_BX_EXCRET 11
+/* For instructions which want an immediate exit to the main loop,
+ * as opposed to attempting to use lookup_and_goto_ptr.
+ */
+#define DISAS_EXIT 12
#ifdef TARGET_AARCH64
void a64_translate_init(void);
--
2.9.3
