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py/obj: Add slot-index mp_obj_type_t representation.
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The existings mp_obj_type_t uses a sparse representation for slots for the
capability methods of the type (eg print, make_new).  This commit adds a
compact slot-index representation.  The basic idea is that where the
mp_obj_type_t struct used to have 12 pointer fields, it now has 12 uint8_t
indices, and a variable-length array of pointers.  So in the best case (no
fields used) it saves 12x4-12=36 bytes (on a 32-bit machine) and in the
common case (three fields used) it saves 9x4-12=24 bytes.

Overall with all associated changes, this slot-index representation reduces
code size by 1000 to 3000 bytes on bare-metal ports.  Performance is
marginally better on a few tests (eg about 1% better on misc_pystone.py and
misc_raytrace.py on PYBv1.1), but overall marginally worse by a percent or
so.

See issue #7542 for further analysis and discussion.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
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@jimmo @dpgeorge
jimmo authored and dpgeorge committed Sep 19, 2022
1 parent a52cd5b commit 3ac8b58
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Showing 2 changed files with 125 additions and 3 deletions.
7 changes: 7 additions & 0 deletions py/mpconfig.h
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Original file line number Diff line number Diff line change
Expand Up @@ -145,6 +145,13 @@
#define MICROPY_OBJ_IMMEDIATE_OBJS (MICROPY_OBJ_REPR != MICROPY_OBJ_REPR_D)
#endif

#define MICROPY_OBJ_TYPE_REPR_FULL (0)
#define MICROPY_OBJ_TYPE_REPR_SLOT_INDEX (1)

#ifndef MICROPY_OBJ_TYPE_REPR
#define MICROPY_OBJ_TYPE_REPR (MICROPY_OBJ_TYPE_REPR_FULL)
#endif

/*****************************************************************************/
/* Memory allocation policy */

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121 changes: 118 additions & 3 deletions py/obj.h
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Original file line number Diff line number Diff line change
Expand Up @@ -575,12 +575,13 @@ struct _mp_obj_type_t {
// The name of this type, a qstr.
uint16_t name;

// Corresponds to __repr__ and __str__ special methods.
mp_print_fun_t print;

// Corresponds to __new__ and __init__ special methods, to make an instance of the type.
mp_make_new_fun_t make_new;

#if MICROPY_OBJ_TYPE_REPR == MICROPY_OBJ_TYPE_REPR_FULL
// Corresponds to __repr__ and __str__ special methods.
mp_print_fun_t print;

// Corresponds to __call__ special method, ie T(...).
mp_call_fun_t call;

Expand Down Expand Up @@ -633,17 +634,87 @@ struct _mp_obj_type_t {

// A dict mapping qstrs to objects local methods/constants/etc.
struct _mp_obj_dict_t *locals_dict;

#elif MICROPY_OBJ_TYPE_REPR == MICROPY_OBJ_TYPE_REPR_SLOT_INDEX

// Ideally these would be only 4 bits, but the extra overhead of
// accessing them adds more code, and we also need to be able to
// take the address of them for mp_obj_class_lookup.
uint8_t slot_index_print;
uint8_t slot_index_call;
uint8_t slot_index_unary_op;
uint8_t slot_index_binary_op;
uint8_t slot_index_attr;
uint8_t slot_index_subscr;
uint8_t slot_index_getiter;
uint8_t slot_index_iternext;
uint8_t slot_index_buffer;
uint8_t slot_index_protocol;
uint8_t slot_index_parent;
uint8_t slot_index_locals_dict;

const void *slots[];

#endif
};

// Non-variable sized versions of mp_obj_type_t to be used as a member
// in other structs or for dynamic allocation. The fields are exactly
// as in mp_obj_type_t, but with a fixed size for the flexible array
// members.
#if MICROPY_OBJ_TYPE_REPR == MICROPY_OBJ_TYPE_REPR_FULL
typedef mp_obj_type_t mp_obj_empty_type_t;
typedef mp_obj_type_t mp_obj_full_type_t;
#else
typedef struct _mp_obj_empty_type_t {
mp_obj_base_t base;
uint16_t flags;
uint16_t name;
mp_make_new_fun_t make_new;

uint8_t slot_index_print;
uint8_t slot_index_call;
uint8_t slot_index_unary_op;
uint8_t slot_index_binary_op;
uint8_t slot_index_attr;
uint8_t slot_index_subscr;
uint8_t slot_index_getiter;
uint8_t slot_index_iternext;
uint8_t slot_index_buffer;
uint8_t slot_index_protocol;
uint8_t slot_index_parent;
uint8_t slot_index_locals_dict;

// No slots member.
} mp_obj_empty_type_t;

typedef struct _mp_obj_full_type_t {
mp_obj_base_t base;
uint16_t flags;
uint16_t name;
mp_make_new_fun_t make_new;

uint8_t slot_index_print;
uint8_t slot_index_call;
uint8_t slot_index_unary_op;
uint8_t slot_index_binary_op;
uint8_t slot_index_attr;
uint8_t slot_index_subscr;
uint8_t slot_index_getiter;
uint8_t slot_index_iternext;
uint8_t slot_index_buffer;
uint8_t slot_index_protocol;
uint8_t slot_index_parent;
uint8_t slot_index_locals_dict;

// Explicitly add 12 slots.
const void *slots[12];
} mp_obj_full_type_t;
#endif

#define MP_TYPE_NULL_MAKE_NEW (NULL)

#if MICROPY_OBJ_TYPE_REPR == MICROPY_OBJ_TYPE_REPR_FULL
// Implementation of MP_DEFINE_CONST_OBJ_TYPE for each number of arguments.
// Do not use these directly, instead use MP_DEFINE_CONST_OBJ_TYPE.
#define MP_DEFINE_CONST_OBJ_TYPE_NARGS_0(_struct_type, _typename, _name, _flags, _make_new) const _struct_type _typename = { .base = { &mp_type_type }, .name = _name, .flags = _flags, .make_new = _make_new }
Expand All @@ -670,6 +741,50 @@ typedef mp_obj_type_t mp_obj_full_type_t;
#define MP_OBJ_TYPE_OFFSETOF_SLOT(f) (offsetof(mp_obj_type_t, f))
#define MP_OBJ_TYPE_HAS_SLOT_BY_OFFSET(t, offset) (*(void **)((char *)(t) + (offset)) != NULL)

#elif MICROPY_OBJ_TYPE_REPR == MICROPY_OBJ_TYPE_REPR_SLOT_INDEX

#define _MP_OBJ_TYPE_SLOT_TYPE_print (mp_print_fun_t)
#define _MP_OBJ_TYPE_SLOT_TYPE_call (mp_call_fun_t)
#define _MP_OBJ_TYPE_SLOT_TYPE_unary_op (mp_unary_op_fun_t)
#define _MP_OBJ_TYPE_SLOT_TYPE_binary_op (mp_binary_op_fun_t)
#define _MP_OBJ_TYPE_SLOT_TYPE_attr (mp_attr_fun_t)
#define _MP_OBJ_TYPE_SLOT_TYPE_subscr (mp_subscr_fun_t)
#define _MP_OBJ_TYPE_SLOT_TYPE_getiter (mp_getiter_fun_t)
#define _MP_OBJ_TYPE_SLOT_TYPE_iternext (mp_fun_1_t)
#define _MP_OBJ_TYPE_SLOT_TYPE_buffer (mp_buffer_fun_t)
#define _MP_OBJ_TYPE_SLOT_TYPE_protocol (const void *)
#define _MP_OBJ_TYPE_SLOT_TYPE_parent (const void *)
#define _MP_OBJ_TYPE_SLOT_TYPE_locals_dict (struct _mp_obj_dict_t *)

// Implementation of MP_DEFINE_CONST_OBJ_TYPE for each number of arguments.
// Do not use these directly, instead use MP_DEFINE_CONST_OBJ_TYPE.
// Generated with:
// for i in range(13):
// print(f"#define MP_DEFINE_CONST_OBJ_TYPE_NARGS_{i}(_struct_type, _typename, _name, _flags, _make_new{''.join(f', f{j+1}, v{j+1}' for j in range(i))}) const _struct_type _typename = {{ .base = {{ &mp_type_type }}, .name = _name, .flags = _flags, .make_new = _make_new{''.join(f', .slot_index_##f{j+1} = {j+1}' for j in range(i))}{', .slots = { ' + ''.join(f'v{j+1}, ' for j in range(i)) + '}' if i else '' } }}")
#define MP_DEFINE_CONST_OBJ_TYPE_NARGS_0(_struct_type, _typename, _name, _flags, _make_new) const _struct_type _typename = { .base = { &mp_type_type }, .name = _name, .flags = _flags, .make_new = _make_new }
#define MP_DEFINE_CONST_OBJ_TYPE_NARGS_1(_struct_type, _typename, _name, _flags, _make_new, f1, v1) const _struct_type _typename = { .base = { &mp_type_type }, .name = _name, .flags = _flags, .make_new = _make_new, .slot_index_##f1 = 1, .slots = { v1, } }
#define MP_DEFINE_CONST_OBJ_TYPE_NARGS_2(_struct_type, _typename, _name, _flags, _make_new, f1, v1, f2, v2) const _struct_type _typename = { .base = { &mp_type_type }, .name = _name, .flags = _flags, .make_new = _make_new, .slot_index_##f1 = 1, .slot_index_##f2 = 2, .slots = { v1, v2, } }
#define MP_DEFINE_CONST_OBJ_TYPE_NARGS_3(_struct_type, _typename, _name, _flags, _make_new, f1, v1, f2, v2, f3, v3) const _struct_type _typename = { .base = { &mp_type_type }, .name = _name, .flags = _flags, .make_new = _make_new, .slot_index_##f1 = 1, .slot_index_##f2 = 2, .slot_index_##f3 = 3, .slots = { v1, v2, v3, } }
#define MP_DEFINE_CONST_OBJ_TYPE_NARGS_4(_struct_type, _typename, _name, _flags, _make_new, f1, v1, f2, v2, f3, v3, f4, v4) const _struct_type _typename = { .base = { &mp_type_type }, .name = _name, .flags = _flags, .make_new = _make_new, .slot_index_##f1 = 1, .slot_index_##f2 = 2, .slot_index_##f3 = 3, .slot_index_##f4 = 4, .slots = { v1, v2, v3, v4, } }
#define MP_DEFINE_CONST_OBJ_TYPE_NARGS_5(_struct_type, _typename, _name, _flags, _make_new, f1, v1, f2, v2, f3, v3, f4, v4, f5, v5) const _struct_type _typename = { .base = { &mp_type_type }, .name = _name, .flags = _flags, .make_new = _make_new, .slot_index_##f1 = 1, .slot_index_##f2 = 2, .slot_index_##f3 = 3, .slot_index_##f4 = 4, .slot_index_##f5 = 5, .slots = { v1, v2, v3, v4, v5, } }
#define MP_DEFINE_CONST_OBJ_TYPE_NARGS_6(_struct_type, _typename, _name, _flags, _make_new, f1, v1, f2, v2, f3, v3, f4, v4, f5, v5, f6, v6) const _struct_type _typename = { .base = { &mp_type_type }, .name = _name, .flags = _flags, .make_new = _make_new, .slot_index_##f1 = 1, .slot_index_##f2 = 2, .slot_index_##f3 = 3, .slot_index_##f4 = 4, .slot_index_##f5 = 5, .slot_index_##f6 = 6, .slots = { v1, v2, v3, v4, v5, v6, } }
#define MP_DEFINE_CONST_OBJ_TYPE_NARGS_7(_struct_type, _typename, _name, _flags, _make_new, f1, v1, f2, v2, f3, v3, f4, v4, f5, v5, f6, v6, f7, v7) const _struct_type _typename = { .base = { &mp_type_type }, .name = _name, .flags = _flags, .make_new = _make_new, .slot_index_##f1 = 1, .slot_index_##f2 = 2, .slot_index_##f3 = 3, .slot_index_##f4 = 4, .slot_index_##f5 = 5, .slot_index_##f6 = 6, .slot_index_##f7 = 7, .slots = { v1, v2, v3, v4, v5, v6, v7, } }
#define MP_DEFINE_CONST_OBJ_TYPE_NARGS_8(_struct_type, _typename, _name, _flags, _make_new, f1, v1, f2, v2, f3, v3, f4, v4, f5, v5, f6, v6, f7, v7, f8, v8) const _struct_type _typename = { .base = { &mp_type_type }, .name = _name, .flags = _flags, .make_new = _make_new, .slot_index_##f1 = 1, .slot_index_##f2 = 2, .slot_index_##f3 = 3, .slot_index_##f4 = 4, .slot_index_##f5 = 5, .slot_index_##f6 = 6, .slot_index_##f7 = 7, .slot_index_##f8 = 8, .slots = { v1, v2, v3, v4, v5, v6, v7, v8, } }
#define MP_DEFINE_CONST_OBJ_TYPE_NARGS_9(_struct_type, _typename, _name, _flags, _make_new, f1, v1, f2, v2, f3, v3, f4, v4, f5, v5, f6, v6, f7, v7, f8, v8, f9, v9) const _struct_type _typename = { .base = { &mp_type_type }, .name = _name, .flags = _flags, .make_new = _make_new, .slot_index_##f1 = 1, .slot_index_##f2 = 2, .slot_index_##f3 = 3, .slot_index_##f4 = 4, .slot_index_##f5 = 5, .slot_index_##f6 = 6, .slot_index_##f7 = 7, .slot_index_##f8 = 8, .slot_index_##f9 = 9, .slots = { v1, v2, v3, v4, v5, v6, v7, v8, v9, } }
#define MP_DEFINE_CONST_OBJ_TYPE_NARGS_10(_struct_type, _typename, _name, _flags, _make_new, f1, v1, f2, v2, f3, v3, f4, v4, f5, v5, f6, v6, f7, v7, f8, v8, f9, v9, f10, v10) const _struct_type _typename = { .base = { &mp_type_type }, .name = _name, .flags = _flags, .make_new = _make_new, .slot_index_##f1 = 1, .slot_index_##f2 = 2, .slot_index_##f3 = 3, .slot_index_##f4 = 4, .slot_index_##f5 = 5, .slot_index_##f6 = 6, .slot_index_##f7 = 7, .slot_index_##f8 = 8, .slot_index_##f9 = 9, .slot_index_##f10 = 10, .slots = { v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, } }
#define MP_DEFINE_CONST_OBJ_TYPE_NARGS_11(_struct_type, _typename, _name, _flags, _make_new, f1, v1, f2, v2, f3, v3, f4, v4, f5, v5, f6, v6, f7, v7, f8, v8, f9, v9, f10, v10, f11, v11) const _struct_type _typename = { .base = { &mp_type_type }, .name = _name, .flags = _flags, .make_new = _make_new, .slot_index_##f1 = 1, .slot_index_##f2 = 2, .slot_index_##f3 = 3, .slot_index_##f4 = 4, .slot_index_##f5 = 5, .slot_index_##f6 = 6, .slot_index_##f7 = 7, .slot_index_##f8 = 8, .slot_index_##f9 = 9, .slot_index_##f10 = 10, .slot_index_##f11 = 11, .slots = { v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, } }
#define MP_DEFINE_CONST_OBJ_TYPE_NARGS_12(_struct_type, _typename, _name, _flags, _make_new, f1, v1, f2, v2, f3, v3, f4, v4, f5, v5, f6, v6, f7, v7, f8, v8, f9, v9, f10, v10, f11, v11, f12, v12) const _struct_type _typename = { .base = { &mp_type_type }, .name = _name, .flags = _flags, .make_new = _make_new, .slot_index_##f1 = 1, .slot_index_##f2 = 2, .slot_index_##f3 = 3, .slot_index_##f4 = 4, .slot_index_##f5 = 5, .slot_index_##f6 = 6, .slot_index_##f7 = 7, .slot_index_##f8 = 8, .slot_index_##f9 = 9, .slot_index_##f10 = 10, .slot_index_##f11 = 11, .slot_index_##f12 = 12, .slots = { v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, } }

#define MP_OBJ_TYPE_HAS_SLOT(t, f) ((t)->slot_index_##f)
#define MP_OBJ_TYPE_GET_SLOT(t, f) (_MP_OBJ_TYPE_SLOT_TYPE_##f(t)->slots[(t)->slot_index_##f - 1])
#define MP_OBJ_TYPE_GET_SLOT_OR_NULL(t, f) (_MP_OBJ_TYPE_SLOT_TYPE_##f(MP_OBJ_TYPE_HAS_SLOT(t, f) ? MP_OBJ_TYPE_GET_SLOT(t, f) : NULL))
#define MP_OBJ_TYPE_SET_SLOT(t, f, v, n) ((t)->slot_index_##f = (n) + 1, (t)->slots[(t)->slot_index_##f - 1] = (void *)v)
#define MP_OBJ_TYPE_OFFSETOF_SLOT(f) (offsetof(mp_obj_type_t, slot_index_##f))
// For everything except make_new, the offset is to the uint8_t index. For make_new, we need to check the pointer.
#define MP_OBJ_TYPE_HAS_SLOT_BY_OFFSET(t, offset) (*(uint8_t *)((char *)(t) + (offset)) != 0 || (offset == offsetof(mp_obj_type_t, make_new) && t->make_new))

#endif

// Workaround for https://docs.microsoft.com/en-us/cpp/preprocessor/preprocessor-experimental-overview?view=msvc-160#macro-arguments-are-unpacked
#define MP_DEFINE_CONST_OBJ_TYPE_EXPAND(x) x

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