diff options
| author | Emilio G. Cota <cota@braap.org> | 2017-04-26 23:29:20 -0400 |
|---|---|---|
| committer | Richard Henderson <rth@twiddle.net> | 2017-06-05 09:25:42 -0700 |
| commit | 8a6b28c7b5104263344508df0f4bce97f22cfcaf (patch) | |
| tree | e92b12ce63dddf8869c9915977293fa15da3c6be /target/arm/translate.h | |
| parent | 7ad55b4ffd982c80f26f7f3658138d94cdc678e8 (diff) | |
| download | qemu-8a6b28c7b5104263344508df0f4bce97f22cfcaf.tar.gz | |
target/arm: optimize indirect branches
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..........................................................#++#.........................................+-+
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| +++ **** # # # |
1.2x +-+...................................####............*..*..#......#..#.........................................+-+
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1.15x +-+................................*..*..#............*..*..#......#..#.....#..#................................+-+
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| * * # # # * * # # # # # #### |
1.1x +-+................................*..*..#......#..#..*..*..#......#..#.....#..#.........................#..#...+-+
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1.05x +-+..........................####..*..*..#......#..#..*..*..#......#..#.....#..#......+++............*****..#...+-+
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| *****### +++#### * * # * * # ***** # * * # * * # * * # * | *++# * * # * * # |
1x +-++-+*+++*-+#++****++#++*+-+*++#+-*++*++#-+*+++*-+#++*++*++#++*+-+*++#+-*++*++#-+*+++*-+#++*++*++#++*+-+*++#+-++-+
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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 <cota@braap.org>
Message-Id: <1493263764-18657-8-git-send-email-cota@braap.org>
[rth: Replace gen_jr global variable with DISAS_EXIT state.]
Signed-off-by: Richard Henderson <rth@twiddle.net>
Diffstat (limited to 'target/arm/translate.h')
| -rw-r--r-- | target/arm/translate.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/target/arm/translate.h b/target/arm/translate.h index 6b2cc34c33..15d383d9af 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); |