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all: Remove MICROPY_OPT_CACHE_MAP_LOOKUP_IN_BYTECODE.

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This commit removes all parts of code associated with the existing
MICROPY_OPT_CACHE_MAP_LOOKUP_IN_BYTECODE optimisation option, including the
-mcache-lookup-bc option to mpy-cross.

This feature originally provided a significant performance boost for Unix,
but wasn't able to be enabled for MCU targets (due to frozen bytecode), and
added significant extra complexity to generating and distributing .mpy
files.

The equivalent performance gain is now provided by the combination of
MICROPY_OPT_LOAD_ATTR_FAST_PATH and MICROPY_OPT_MAP_LOOKUP_CACHE (which has
been enabled on the unix port in the previous commit).

It's hard to provide precise performance numbers, but tests have been run
on a wide variety of architectures (x86-64, ARM Cortex, Aarch64, RISC-V,
xtensa) and they all generally agree on the qualitative improvements seen
by the combination of MICROPY_OPT_LOAD_ATTR_FAST_PATH and
MICROPY_OPT_MAP_LOOKUP_CACHE.

For example, on a "quiet" Linux x64 environment (i3-5010U @ 2.10GHz) the
change from CACHE_MAP_LOOKUP_IN_BYTECODE, to LOAD_ATTR_FAST_PATH combined
with MAP_LOOKUP_CACHE is:

diff of scores (higher is better)
N=2000 M=2000       bccache -> attrmapcache      diff      diff% (error%)
bm_chaos.py        13742.56 ->   13905.67 :   +163.11 =  +1.187% (+/-3.75%)
bm_fannkuch.py        60.13 ->      61.34 :     +1.21 =  +2.012% (+/-2.11%)
bm_fft.py         113083.20 ->  114793.68 :  +1710.48 =  +1.513% (+/-1.57%)
bm_float.py       256552.80 ->  243908.29 : -12644.51 =  -4.929% (+/-1.90%)
bm_hexiom.py         521.93 ->     625.41 :   +103.48 = +19.826% (+/-0.40%)
bm_nqueens.py     197544.25 ->  217713.12 : +20168.87 = +10.210% (+/-3.01%)
bm_pidigits.py      8072.98 ->    8198.75 :   +125.77 =  +1.558% (+/-3.22%)
misc_aes.py        17283.45 ->   16480.52 :   -802.93 =  -4.646% (+/-0.82%)
misc_mandel.py     99083.99 ->  128939.84 : +29855.85 = +30.132% (+/-5.88%)
misc_pystone.py    83860.10 ->   82592.56 :  -1267.54 =  -1.511% (+/-2.27%)
misc_raytrace.py   21490.40 ->   22227.23 :   +736.83 =  +3.429% (+/-1.88%)

This shows that the new optimisations are at least as good as the existing
inline-bytecode-caching, and are sometimes much better (because the new
ones apply caching to a wider variety of map lookups).

The new optimisations can also benefit code generated by the native
emitter, because they apply to the runtime rather than the generated code.
The improvement for the native emitter when LOAD_ATTR_FAST_PATH and
MAP_LOOKUP_CACHE are enabled is (same Linux environment as above):

diff of scores (higher is better)
N=2000 M=2000        native -> nat-attrmapcache  diff      diff% (error%)
bm_chaos.py        14130.62 ->   15464.68 :  +1334.06 =  +9.441% (+/-7.11%)
bm_fannkuch.py        74.96 ->      76.16 :     +1.20 =  +1.601% (+/-1.80%)
bm_fft.py         166682.99 ->  168221.86 :  +1538.87 =  +0.923% (+/-4.20%)
bm_float.py       233415.23 ->  265524.90 : +32109.67 = +13.756% (+/-2.57%)
bm_hexiom.py         628.59 ->     734.17 :   +105.58 = +16.796% (+/-1.39%)
bm_nqueens.py     225418.44 ->  232926.45 :  +7508.01 =  +3.331% (+/-3.10%)
bm_pidigits.py      6322.00 ->    6379.52 :    +57.52 =  +0.910% (+/-5.62%)
misc_aes.py        20670.10 ->   27223.18 :  +6553.08 = +31.703% (+/-1.56%)
misc_mandel.py    138221.11 ->  152014.01 : +13792.90 =  +9.979% (+/-2.46%)
misc_pystone.py    85032.14 ->  105681.44 : +20649.30 = +24.284% (+/-2.25%)
misc_raytrace.py   19800.01 ->   23350.73 :  +3550.72 = +17.933% (+/-2.79%)

In summary, compared to MICROPY_OPT_CACHE_MAP_LOOKUP_IN_BYTECODE, the new
MICROPY_OPT_LOAD_ATTR_FAST_PATH and MICROPY_OPT_MAP_LOOKUP_CACHE options:
- are simpler;
- take less code size;
- are faster (generally);
- work with code generated by the native emitter;
- can be used on embedded targets with a small and constant RAM overhead;
- allow the same .mpy bytecode to run on all targets.

See #7680 for further discussion.  And see also #7653 for a discussion
about simplifying mpy-cross options.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
This commit is contained in:
Jim Mussared
2021-09-06 12:28:06 +10:00
committed by Damien George
parent 60c6d5594f
commit b326edf68c
32 changed files with 42 additions and 260 deletions
Download Patch File Download Diff File Expand all files Collapse all files

5
mpy-cross/README.md
View File

@@ -17,10 +17,7 @@ by the target MicroPython runtime (eg onto a pyboard's filesystem), and then
imported like any other Python module using `import foo`.
Different target runtimes may require a different format of the compiled
bytecode, and such options can be passed to the cross compiler. For example,
the unix port of MicroPython requires the following:
$ ./mpy-cross -mcache-lookup-bc foo.py
bytecode, and such options can be passed to the cross compiler.
If the Python code contains `@native` or `@viper` annotations, then you must
specify `-march` to match the target architecture.

6
mpy-cross/main.c
View File

@@ -108,7 +108,6 @@ STATIC int usage(char **argv) {
"Target specific options:\n"
"-msmall-int-bits=number : set the maximum bits used to encode a small-int\n"
"-mno-unicode : don't support unicode in compiled strings\n"
"-mcache-lookup-bc : cache map lookups in the bytecode\n"
"-march=<arch> : set architecture for native emitter; x86, x64, armv6, armv7m, armv7em, armv7emsp, armv7emdp, xtensa, xtensawin\n"
"\n"
"Implementation specific options:\n", argv[0]
@@ -205,7 +204,6 @@ MP_NOINLINE int main_(int argc, char **argv) {
// set default compiler configuration
mp_dynamic_compiler.small_int_bits = 31;
mp_dynamic_compiler.opt_cache_map_lookup_in_bytecode = 0;
mp_dynamic_compiler.py_builtins_str_unicode = 1;
#if defined(__i386__)
mp_dynamic_compiler.native_arch = MP_NATIVE_ARCH_X86;
@@ -264,10 +262,6 @@ MP_NOINLINE int main_(int argc, char **argv) {
return usage(argv);
}
// TODO check that small_int_bits is within range of host's capabilities
} else if (strcmp(argv[a], "-mno-cache-lookup-bc") == 0) {
mp_dynamic_compiler.opt_cache_map_lookup_in_bytecode = 0;
} else if (strcmp(argv[a], "-mcache-lookup-bc") == 0) {
mp_dynamic_compiler.opt_cache_map_lookup_in_bytecode = 1;
} else if (strcmp(argv[a], "-mno-unicode") == 0) {
mp_dynamic_compiler.py_builtins_str_unicode = 0;
} else if (strcmp(argv[a], "-municode") == 0) {

2
mpy-cross/mpconfigport.h
View File

@@ -57,8 +57,6 @@
#define MICROPY_COMP_TRIPLE_TUPLE_ASSIGN (1)
#define MICROPY_COMP_RETURN_IF_EXPR (1)
#define MICROPY_OPT_CACHE_MAP_LOOKUP_IN_BYTECODE (0)
#define MICROPY_READER_POSIX (1)
#define MICROPY_ENABLE_RUNTIME (0)
#define MICROPY_ENABLE_GC (1)