Lerking/micropython
1
0
Fork 0
mirror of https://github.com/micropython/micropython.git synced 2026-01-06 12:10:13 +01:00
Code Issues Actions 27 Packages Projects Releases Wiki Activity

py: Add option to cache map lookup results in bytecode.

Browse Source 
This is a simple optimisation inspired by JITing technology: we cache in
the bytecode (using 1 byte) the offset of the last successful lookup in
a map. This allows us next time round to check in that location in the
hash table (mp_map_t) for the desired entry, and if it's there use that
entry straight away.  Otherwise fallback to a normal map lookup.

Works for LOAD_NAME, LOAD_GLOBAL, LOAD_ATTR and STORE_ATTR opcodes.

On a few tests it gives >90% cache hit and greatly improves speed of
code.

Disabled by default.  Enabled for unix and stmhal ports.
This commit is contained in:
Damien George
2015-01-06 12:51:39 +00:00
parent b4b10fd350
commit 7ee91cf861
7 changed files with 142 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

113
py/vm.c
View File

@@ -32,6 +32,7 @@
#include "py/mpstate.h"
#include "py/nlr.h"
#include "py/emitglue.h"
#include "py/objtype.h"
#include "py/runtime.h"
#include "py/bc0.h"
#include "py/bc.h"
@@ -248,26 +249,101 @@ dispatch_loop:
goto load_check;
}
#if !MICROPY_OPT_CACHE_MAP_LOOKUP_IN_BYTECODE
ENTRY(MP_BC_LOAD_NAME): {
MARK_EXC_IP_SELECTIVE();
DECODE_QSTR;
PUSH(mp_load_name(qst));
DISPATCH();
}
#else
ENTRY(MP_BC_LOAD_NAME): {
MARK_EXC_IP_SELECTIVE();
DECODE_QSTR;
mp_obj_t key = MP_OBJ_NEW_QSTR(qst);
mp_uint_t x = *ip;
if (x < MP_STATE_CTX(dict_locals)->map.alloc && MP_STATE_CTX(dict_locals)->map.table[x].key == key) {
PUSH(MP_STATE_CTX(dict_locals)->map.table[x].value);
} else {
mp_map_elem_t *elem = mp_map_lookup(&MP_STATE_CTX(dict_locals)->map, MP_OBJ_NEW_QSTR(qst), MP_MAP_LOOKUP);
if (elem != NULL) {
*(byte*)ip = (elem - &MP_STATE_CTX(dict_locals)->map.table[0]) & 0xff;
PUSH(elem->value);
} else {
PUSH(mp_load_name(MP_OBJ_QSTR_VALUE(key)));
}
}
ip++;
DISPATCH();
}
#endif
#if !MICROPY_OPT_CACHE_MAP_LOOKUP_IN_BYTECODE
ENTRY(MP_BC_LOAD_GLOBAL): {
MARK_EXC_IP_SELECTIVE();
DECODE_QSTR;
PUSH(mp_load_global(qst));
DISPATCH();
}
#else
ENTRY(MP_BC_LOAD_GLOBAL): {
MARK_EXC_IP_SELECTIVE();
DECODE_QSTR;
mp_obj_t key = MP_OBJ_NEW_QSTR(qst);
mp_uint_t x = *ip;
if (x < MP_STATE_CTX(dict_globals)->map.alloc && MP_STATE_CTX(dict_globals)->map.table[x].key == key) {
PUSH(MP_STATE_CTX(dict_globals)->map.table[x].value);
} else {
mp_map_elem_t *elem = mp_map_lookup(&MP_STATE_CTX(dict_globals)->map, MP_OBJ_NEW_QSTR(qst), MP_MAP_LOOKUP);
if (elem != NULL) {
*(byte*)ip = (elem - &MP_STATE_CTX(dict_globals)->map.table[0]) & 0xff;
PUSH(elem->value);
} else {
PUSH(mp_load_global(MP_OBJ_QSTR_VALUE(key)));
}
}
ip++;
DISPATCH();
}
#endif
#if !MICROPY_OPT_CACHE_MAP_LOOKUP_IN_BYTECODE
ENTRY(MP_BC_LOAD_ATTR): {
MARK_EXC_IP_SELECTIVE();
DECODE_QSTR;
SET_TOP(mp_load_attr(TOP(), qst));
DISPATCH();
}
#else
ENTRY(MP_BC_LOAD_ATTR): {
MARK_EXC_IP_SELECTIVE();
DECODE_QSTR;
mp_obj_t top = TOP();
if (mp_obj_get_type(top)->load_attr == mp_obj_instance_load_attr) {
mp_obj_instance_t *self = top;
mp_uint_t x = *ip;
mp_obj_t key = MP_OBJ_NEW_QSTR(qst);
mp_map_elem_t *elem;
if (x < self->members.alloc && self->members.table[x].key == key) {
elem = &self->members.table[x];
} else {
elem = mp_map_lookup(&self->members, key, MP_MAP_LOOKUP);
if (elem != NULL) {
*(byte*)ip = elem - &self->members.table[0];
} else {
goto load_attr_cache_fail;
}
}
SET_TOP(elem->value);
ip++;
DISPATCH();
}
load_attr_cache_fail:
SET_TOP(mp_load_attr(top, qst));
ip++;
DISPATCH();
}
#endif
ENTRY(MP_BC_LOAD_METHOD): {
MARK_EXC_IP_SELECTIVE();
@@ -315,6 +391,7 @@ dispatch_loop:
DISPATCH();
}
#if !MICROPY_OPT_CACHE_MAP_LOOKUP_IN_BYTECODE
ENTRY(MP_BC_STORE_ATTR): {
MARK_EXC_IP_SELECTIVE();
DECODE_QSTR;
@@ -322,6 +399,42 @@ dispatch_loop:
sp -= 2;
DISPATCH();
}
#else
// This caching code works with MICROPY_PY_BUILTINS_PROPERTY enabled because
// if the attr exists in self->members then it can't be a property. A
// consequence of this is that we can't use MP_MAP_LOOKUP_ADD_IF_NOT_FOUND
// in the fast-path below, because that store could override a property.
ENTRY(MP_BC_STORE_ATTR): {
MARK_EXC_IP_SELECTIVE();
DECODE_QSTR;
mp_obj_t top = TOP();
if (mp_obj_get_type(top)->store_attr == mp_obj_instance_store_attr && sp[-1] != MP_OBJ_NULL) {
mp_obj_instance_t *self = top;
mp_uint_t x = *ip;
mp_obj_t key = MP_OBJ_NEW_QSTR(qst);
mp_map_elem_t *elem;
if (x < self->members.alloc && self->members.table[x].key == key) {
elem = &self->members.table[x];
} else {
elem = mp_map_lookup(&self->members, key, MP_MAP_LOOKUP);
if (elem != NULL) {
*(byte*)ip = elem - &self->members.table[0];
} else {
goto store_attr_cache_fail;
}
}
elem->value = sp[-1];
sp -= 2;
ip++;
DISPATCH();
}
store_attr_cache_fail:
mp_store_attr(sp[0], qst, sp[-1]);
sp -= 2;
ip++;
DISPATCH();
}
#endif
ENTRY(MP_BC_STORE_SUBSCR):
MARK_EXC_IP_SELECTIVE();