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circuitpython/py/bc.c
Damien George 5640e6dacd py: Provide mp_decode_uint_value to help optimise stack usage. 
This has a noticeable improvement on x86-64 and Thumb2 archs, where stack
usage is reduced by 2 machine words in the VM.
2017-03-17 16:50:19 +11:00

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/*
* This file is part of the Micro Python project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2014 Damien P. George
* Copyright (c) 2014 Paul Sokolovsky
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <stdbool.h>
#include <string.h>
#include <assert.h>
#include "py/nlr.h"
#include "py/objfun.h"
#include "py/runtime0.h"
#include "py/bc0.h"
#include "py/bc.h"
#if 0 // print debugging info
#define DEBUG_PRINT (1)
#else // don't print debugging info
#define DEBUG_PRINT (0)
#define DEBUG_printf(...) (void)0
#endif
mp_uint_t mp_decode_uint(const byte **ptr) {
mp_uint_t unum = 0;
byte val;
const byte *p = *ptr;
do {
val = *p++;
unum = (unum << 7) | (val & 0x7f);
} while ((val & 0x80) != 0);
*ptr = p;
return unum;
}
// This function is used to help reduce stack usage at the caller, for the case when
// the caller doesn't need to increase the ptr argument. If ptr is a local variable
// and the caller uses mp_decode_uint(&ptr) instead of this function, then the compiler
// must allocate a slot on the stack for ptr, and this slot cannot be reused for
// anything else in the function because the pointer may have been stored in a global
// and reused later in the function.
mp_uint_t mp_decode_uint_value(const byte *ptr) {
return mp_decode_uint(&ptr);
}
STATIC NORETURN void fun_pos_args_mismatch(mp_obj_fun_bc_t *f, size_t expected, size_t given) {
#if MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE
// generic message, used also for other argument issues
(void)f;
(void)expected;
(void)given;
mp_arg_error_terse_mismatch();
#elif MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_NORMAL
(void)f;
nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
"function takes %d positional arguments but %d were given", expected, given));
#elif MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_DETAILED
nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
"%q() takes %d positional arguments but %d were given",
mp_obj_fun_get_name(MP_OBJ_FROM_PTR(f)), expected, given));
#endif
}
#if DEBUG_PRINT
STATIC void dump_args(const mp_obj_t *a, size_t sz) {
DEBUG_printf("%p: ", a);
for (size_t i = 0; i < sz; i++) {
DEBUG_printf("%p ", a[i]);
}
DEBUG_printf("\n");
}
#else
#define dump_args(...) (void)0
#endif
// On entry code_state should be allocated somewhere (stack/heap) and
// contain the following valid entries:
// - code_state->fun_bc should contain a pointer to the function object
// - code_state->ip should contain the offset in bytes from the pointer
// code_state->fun_bc->bytecode to the entry n_state (0 for bytecode, non-zero for native)
void mp_setup_code_state(mp_code_state_t *code_state, size_t n_args, size_t n_kw, const mp_obj_t *args) {
// This function is pretty complicated. It's main aim is to be efficient in speed and RAM
// usage for the common case of positional only args.
// get the function object that we want to set up (could be bytecode or native code)
mp_obj_fun_bc_t *self = code_state->fun_bc;
// ip comes in as an offset into bytecode, so turn it into a true pointer
code_state->ip = self->bytecode + (size_t)code_state->ip;
#if MICROPY_STACKLESS
code_state->prev = NULL;
#endif
// get params
size_t n_state = mp_decode_uint(&code_state->ip);
mp_decode_uint(&code_state->ip); // skip n_exc_stack
size_t scope_flags = *code_state->ip++;
size_t n_pos_args = *code_state->ip++;
size_t n_kwonly_args = *code_state->ip++;
size_t n_def_pos_args = *code_state->ip++;
code_state->sp = &code_state->state[0] - 1;
code_state->exc_sp = (mp_exc_stack_t*)(code_state->state + n_state) - 1;
// zero out the local stack to begin with
memset(code_state->state, 0, n_state * sizeof(*code_state->state));
const mp_obj_t *kwargs = args + n_args;
// var_pos_kw_args points to the stack where the var-args tuple, and var-kw dict, should go (if they are needed)
mp_obj_t *var_pos_kw_args = &code_state->state[n_state - 1 - n_pos_args - n_kwonly_args];
// check positional arguments
if (n_args > n_pos_args) {
// given more than enough arguments
if ((scope_flags & MP_SCOPE_FLAG_VARARGS) == 0) {
fun_pos_args_mismatch(self, n_pos_args, n_args);
}
// put extra arguments in varargs tuple
*var_pos_kw_args-- = mp_obj_new_tuple(n_args - n_pos_args, args + n_pos_args);
n_args = n_pos_args;
} else {
if ((scope_flags & MP_SCOPE_FLAG_VARARGS) != 0) {
DEBUG_printf("passing empty tuple as *args\n");
*var_pos_kw_args-- = mp_const_empty_tuple;
}
// Apply processing and check below only if we don't have kwargs,
// otherwise, kw handling code below has own extensive checks.
if (n_kw == 0 && (scope_flags & MP_SCOPE_FLAG_DEFKWARGS) == 0) {
if (n_args >= (size_t)(n_pos_args - n_def_pos_args)) {
// given enough arguments, but may need to use some default arguments
for (size_t i = n_args; i < n_pos_args; i++) {
code_state->state[n_state - 1 - i] = self->extra_args[i - (n_pos_args - n_def_pos_args)];
}
} else {
fun_pos_args_mismatch(self, n_pos_args - n_def_pos_args, n_args);
}
}
}
// copy positional args into state
for (size_t i = 0; i < n_args; i++) {
code_state->state[n_state - 1 - i] = args[i];
}
// check keyword arguments
if (n_kw != 0 || (scope_flags & MP_SCOPE_FLAG_DEFKWARGS) != 0) {
DEBUG_printf("Initial args: ");
dump_args(code_state->state + n_state - n_pos_args - n_kwonly_args, n_pos_args + n_kwonly_args);
mp_obj_t dict = MP_OBJ_NULL;
if ((scope_flags & MP_SCOPE_FLAG_VARKEYWORDS) != 0) {
dict = mp_obj_new_dict(n_kw); // TODO: better go conservative with 0?
*var_pos_kw_args = dict;
}
// get pointer to arg_names array
const mp_obj_t *arg_names = (const mp_obj_t*)self->const_table;
for (size_t i = 0; i < n_kw; i++) {
// the keys in kwargs are expected to be qstr objects
mp_obj_t wanted_arg_name = kwargs[2 * i];
for (size_t j = 0; j < n_pos_args + n_kwonly_args; j++) {
if (wanted_arg_name == arg_names[j]) {
if (code_state->state[n_state - 1 - j] != MP_OBJ_NULL) {
nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
"function got multiple values for argument '%q'", MP_OBJ_QSTR_VALUE(wanted_arg_name)));
}
code_state->state[n_state - 1 - j] = kwargs[2 * i + 1];
goto continue2;
}
}
// Didn't find name match with positional args
if ((scope_flags & MP_SCOPE_FLAG_VARKEYWORDS) == 0) {
mp_raise_msg(&mp_type_TypeError, "function does not take keyword arguments");
}
mp_obj_dict_store(dict, kwargs[2 * i], kwargs[2 * i + 1]);
continue2:;
}
DEBUG_printf("Args with kws flattened: ");
dump_args(code_state->state + n_state - n_pos_args - n_kwonly_args, n_pos_args + n_kwonly_args);
// fill in defaults for positional args
mp_obj_t *d = &code_state->state[n_state - n_pos_args];
mp_obj_t *s = &self->extra_args[n_def_pos_args - 1];
for (size_t i = n_def_pos_args; i > 0; i--, d++, s--) {
if (*d == MP_OBJ_NULL) {
*d = *s;
}
}
DEBUG_printf("Args after filling default positional: ");
dump_args(code_state->state + n_state - n_pos_args - n_kwonly_args, n_pos_args + n_kwonly_args);
// Check that all mandatory positional args are specified
while (d < &code_state->state[n_state]) {
if (*d++ == MP_OBJ_NULL) {
nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
"function missing required positional argument #%d", &code_state->state[n_state] - d));
}
}
// Check that all mandatory keyword args are specified
// Fill in default kw args if we have them
for (size_t i = 0; i < n_kwonly_args; i++) {
if (code_state->state[n_state - 1 - n_pos_args - i] == MP_OBJ_NULL) {
mp_map_elem_t *elem = NULL;
if ((scope_flags & MP_SCOPE_FLAG_DEFKWARGS) != 0) {
elem = mp_map_lookup(&((mp_obj_dict_t*)MP_OBJ_TO_PTR(self->extra_args[n_def_pos_args]))->map, arg_names[n_pos_args + i], MP_MAP_LOOKUP);
}
if (elem != NULL) {
code_state->state[n_state - 1 - n_pos_args - i] = elem->value;
} else {
nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
"function missing required keyword argument '%q'", MP_OBJ_QSTR_VALUE(arg_names[n_pos_args + i])));
}
}
}
} else {
// no keyword arguments given
if (n_kwonly_args != 0) {
mp_raise_msg(&mp_type_TypeError, "function missing keyword-only argument");
}
if ((scope_flags & MP_SCOPE_FLAG_VARKEYWORDS) != 0) {
*var_pos_kw_args = mp_obj_new_dict(0);
}
}
// get the ip and skip argument names
const byte *ip = code_state->ip;
// jump over code info (source file and line-number mapping)
ip += mp_decode_uint_value(ip);
// bytecode prelude: initialise closed over variables
size_t local_num;
while ((local_num = *ip++) != 255) {
code_state->state[n_state - 1 - local_num] =
mp_obj_new_cell(code_state->state[n_state - 1 - local_num]);
}
// now that we skipped over the prelude, set the ip for the VM
code_state->ip = ip;
DEBUG_printf("Calling: n_pos_args=%d, n_kwonly_args=%d\n", n_pos_args, n_kwonly_args);
dump_args(code_state->state + n_state - n_pos_args - n_kwonly_args, n_pos_args + n_kwonly_args);
dump_args(code_state->state, n_state);
}
#if MICROPY_PERSISTENT_CODE_LOAD || MICROPY_PERSISTENT_CODE_SAVE
// The following table encodes the number of bytes that a specific opcode
// takes up. There are 3 special opcodes that always have an extra byte:
// MP_BC_MAKE_CLOSURE
// MP_BC_MAKE_CLOSURE_DEFARGS
// MP_BC_RAISE_VARARGS
// There are 4 special opcodes that have an extra byte only when
// MICROPY_OPT_CACHE_MAP_LOOKUP_IN_BYTECODE is enabled:
// MP_BC_LOAD_NAME
// MP_BC_LOAD_GLOBAL
// MP_BC_LOAD_ATTR
// MP_BC_STORE_ATTR
#define OC4(a, b, c, d) (a | (b << 2) | (c << 4) | (d << 6))
#define U (0) // undefined opcode
#define B (MP_OPCODE_BYTE) // single byte
#define Q (MP_OPCODE_QSTR) // single byte plus 2-byte qstr
#define V (MP_OPCODE_VAR_UINT) // single byte plus variable encoded unsigned int
#define O (MP_OPCODE_OFFSET) // single byte plus 2-byte bytecode offset
STATIC const byte opcode_format_table[64] = {
OC4(U, U, U, U), // 0x00-0x03
OC4(U, U, U, U), // 0x04-0x07
OC4(U, U, U, U), // 0x08-0x0b
OC4(U, U, U, U), // 0x0c-0x0f
OC4(B, B, B, U), // 0x10-0x13
OC4(V, U, Q, V), // 0x14-0x17
OC4(B, U, V, V), // 0x18-0x1b
OC4(Q, Q, Q, Q), // 0x1c-0x1f
OC4(B, B, V, V), // 0x20-0x23
OC4(Q, Q, Q, B), // 0x24-0x27
OC4(V, V, Q, Q), // 0x28-0x2b
OC4(U, U, U, U), // 0x2c-0x2f
OC4(B, B, B, B), // 0x30-0x33
OC4(B, O, O, O), // 0x34-0x37
OC4(O, O, U, U), // 0x38-0x3b
OC4(U, O, B, O), // 0x3c-0x3f
OC4(O, B, B, O), // 0x40-0x43
OC4(B, B, O, U), // 0x44-0x47
OC4(U, U, U, U), // 0x48-0x4b
OC4(U, U, U, U), // 0x4c-0x4f
OC4(V, V, U, V), // 0x50-0x53
OC4(B, U, V, V), // 0x54-0x57
OC4(V, V, V, B), // 0x58-0x5b
OC4(B, B, B, U), // 0x5c-0x5f
OC4(V, V, V, V), // 0x60-0x63
OC4(V, V, V, V), // 0x64-0x67
OC4(Q, Q, B, U), // 0x68-0x6b
OC4(U, U, U, U), // 0x6c-0x6f
OC4(B, B, B, B), // 0x70-0x73
OC4(B, B, B, B), // 0x74-0x77
OC4(B, B, B, B), // 0x78-0x7b
OC4(B, B, B, B), // 0x7c-0x7f
OC4(B, B, B, B), // 0x80-0x83
OC4(B, B, B, B), // 0x84-0x87
OC4(B, B, B, B), // 0x88-0x8b
OC4(B, B, B, B), // 0x8c-0x8f
OC4(B, B, B, B), // 0x90-0x93
OC4(B, B, B, B), // 0x94-0x97
OC4(B, B, B, B), // 0x98-0x9b
OC4(B, B, B, B), // 0x9c-0x9f
OC4(B, B, B, B), // 0xa0-0xa3
OC4(B, B, B, B), // 0xa4-0xa7
OC4(B, B, B, B), // 0xa8-0xab
OC4(B, B, B, B), // 0xac-0xaf
OC4(B, B, B, B), // 0xb0-0xb3
OC4(B, B, B, B), // 0xb4-0xb7
OC4(B, B, B, B), // 0xb8-0xbb
OC4(B, B, B, B), // 0xbc-0xbf
OC4(B, B, B, B), // 0xc0-0xc3
OC4(B, B, B, B), // 0xc4-0xc7
OC4(B, B, B, B), // 0xc8-0xcb
OC4(B, B, B, B), // 0xcc-0xcf
OC4(B, B, B, B), // 0xd0-0xd3
OC4(B, B, B, B), // 0xd4-0xd7
OC4(B, B, B, B), // 0xd8-0xdb
OC4(B, B, B, B), // 0xdc-0xdf
OC4(B, B, B, B), // 0xe0-0xe3
OC4(B, B, B, B), // 0xe4-0xe7
OC4(B, B, B, B), // 0xe8-0xeb
OC4(B, B, B, B), // 0xec-0xef
OC4(B, B, B, B), // 0xf0-0xf3
OC4(B, B, B, B), // 0xf4-0xf7
OC4(B, B, B, U), // 0xf8-0xfb
OC4(U, U, U, U), // 0xfc-0xff
};
#undef OC4
#undef U
#undef B
#undef Q
#undef V
#undef O
uint mp_opcode_format(const byte *ip, size_t *opcode_size) {
uint f = (opcode_format_table[*ip >> 2] >> (2 * (*ip & 3))) & 3;
const byte *ip_start = ip;
if (f == MP_OPCODE_QSTR) {
ip += 3;
} else {
int extra_byte = (
*ip == MP_BC_RAISE_VARARGS
|| *ip == MP_BC_MAKE_CLOSURE
|| *ip == MP_BC_MAKE_CLOSURE_DEFARGS
#if MICROPY_OPT_CACHE_MAP_LOOKUP_IN_BYTECODE
|| *ip == MP_BC_LOAD_NAME
|| *ip == MP_BC_LOAD_GLOBAL
|| *ip == MP_BC_LOAD_ATTR
|| *ip == MP_BC_STORE_ATTR
#endif
);
ip += 1;
if (f == MP_OPCODE_VAR_UINT) {
while ((*ip++ & 0x80) != 0) {
}
} else if (f == MP_OPCODE_OFFSET) {
ip += 2;
}
ip += extra_byte;
}
*opcode_size = ip - ip_start;
return f;
}
#endif // MICROPY_PERSISTENT_CODE_LOAD || MICROPY_PERSISTENT_CODE_SAVE
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