circuitpython/py/vm.c

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/*
* This file is part of the Micro Python project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2013, 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.
*/
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#include <stdio.h>
#include <string.h>
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#include <assert.h>
#include "mpconfig.h"
#include "nlr.h"
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#include "misc.h"
#include "qstr.h"
#include "obj.h"
#include "emitglue.h"
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#include "runtime.h"
#include "bc0.h"
#include "bc.h"
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#include "objgenerator.h"
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#if 0
#define TRACE(ip) mp_bytecode_print2(ip, 1);
#else
#define TRACE(ip)
#endif
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// Value stack grows up (this makes it incompatible with native C stack, but
// makes sure that arguments to functions are in natural order arg1..argN
// (Python semantics mandates left-to-right evaluation order, including for
// function arguments). Stack pointer is pre-incremented and points at the
// top element.
// Exception stack also grows up, top element is also pointed at.
// Exception stack unwind reasons (WHY_* in CPython-speak)
// TODO perhaps compress this to RETURN=0, JUMP>0, with number of unwinds
// left to do encoded in the JUMP number
typedef enum {
UNWIND_RETURN = 1,
UNWIND_JUMP,
} mp_unwind_reason_t;
#define DECODE_UINT do { \
unum = 0; \
do { \
unum = (unum << 7) + (*ip & 0x7f); \
} while ((*ip++ & 0x80) != 0); \
} while (0)
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#define DECODE_ULABEL do { unum = (ip[0] | (ip[1] << 8)); ip += 2; } while (0)
#define DECODE_SLABEL do { unum = (ip[0] | (ip[1] << 8)) - 0x8000; ip += 2; } while (0)
#define DECODE_QSTR qstr qst = 0; \
do { \
qst = (qst << 7) + (*ip & 0x7f); \
} while ((*ip++ & 0x80) != 0)
#define DECODE_PTR do { \
ip = (byte*)(((mp_uint_t)ip + sizeof(mp_uint_t) - 1) & (~(sizeof(mp_uint_t) - 1))); /* align ip */ \
unum = *(mp_uint_t*)ip; \
ip += sizeof(mp_uint_t); \
} while (0)
#define PUSH(val) *++sp = (val)
#define POP() (*sp--)
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#define TOP() (*sp)
#define SET_TOP(val) *sp = (val)
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#define PUSH_EXC_BLOCK() \
DECODE_ULABEL; /* except labels are always forward */ \
++exc_sp; \
exc_sp->opcode = *code_state->ip; \
exc_sp->handler = ip + unum; \
exc_sp->val_sp = MP_TAGPTR_MAKE(sp, currently_in_except_block); \
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exc_sp->prev_exc = MP_OBJ_NULL; \
currently_in_except_block = 0; /* in a try block now */
#define POP_EXC_BLOCK() \
currently_in_except_block = MP_TAGPTR_TAG(exc_sp->val_sp); /* restore previous state */ \
exc_sp--; /* pop back to previous exception handler */
// fastn has items in reverse order (fastn[0] is local[0], fastn[-1] is local[1], etc)
// sp points to bottom of stack which grows up
// returns:
// MP_VM_RETURN_NORMAL, sp valid, return value in *sp
// MP_VM_RETURN_YIELD, ip, sp valid, yielded value in *sp
// MP_VM_RETURN_EXCEPTION, exception in fastn[0]
mp_vm_return_kind_t mp_execute_bytecode(mp_code_state *code_state, volatile mp_obj_t inject_exc) {
#if MICROPY_OPT_COMPUTED_GOTO
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#include "vmentrytable.h"
#define DISPATCH() do { \
TRACE(ip); \
code_state->ip = ip; \
goto *entry_table[*ip++]; \
} while(0)
#define ENTRY(op) entry_##op
#define ENTRY_DEFAULT entry_default
#else
#define DISPATCH() break
#define ENTRY(op) case op
#define ENTRY_DEFAULT default
#endif
py: Tidy up variables in VM, probably fixes subtle bugs. Things get tricky when using the nlr code to catch exceptions. Need to ensure that the variables (stack layout) in the exception handler are the same as in the bit protected by the exception handler. Prior to this patch there were a few bugs. 1) The constant mp_const_MemoryError_obj was being preloaded to a specific location on the stack at the start of the function. But this location on the stack was being overwritten in the opcode loop (since it didn't think that variable would ever be referenced again), and so when an exception occurred, the variable holding the address of MemoryError was corrupt. 2) The FOR_ITER opcode detection in the exception handler used sp, which may or may not contain the right value coming out of the main opcode loop. With this patch there is a clear separation of variables used in the opcode loop and in the exception handler (should fix issue (2) above). Furthermore, nlr_raise is no longer used in the opcode loop. Instead, it jumps directly into the exception handler. This tells the C compiler more about the possible code flow, and means that it should have the same stack layout for the exception handler. This should fix issue (1) above. Indeed, the generated (ARM) assembler has been checked explicitly, and with 'goto exception_handler', the problem with &MemoryError is fixed. This may now fix problems with rge-sm, and probably many other subtle bugs yet to show themselves. Incidentally, rge-sm now passes on pyboard (with a reduced range of integration)! Main lesson: nlr is tricky. Don't use nlr_push unless you know what you are doing! Luckily, it's not used in many places. Using nlr_raise/jump is fine.
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// nlr_raise needs to be implemented as a goto, so that the C compiler's flow analyser
// sees that it's possible for us to jump from the dispatch loop to the exception
// handler. Without this, the code may have a different stack layout in the dispatch
// loop and the exception handler, leading to very obscure bugs.
#define RAISE(o) do { nlr_pop(); nlr.ret_val = o; goto exception_handler; } while(0)
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// Pointers which are constant for particular invocation of mp_execute_bytecode()
mp_obj_t *const fastn = &code_state->state[code_state->n_state - 1];
mp_exc_stack_t *const exc_stack = (mp_exc_stack_t*)(code_state->state + code_state->n_state);
py: Tidy up variables in VM, probably fixes subtle bugs. Things get tricky when using the nlr code to catch exceptions. Need to ensure that the variables (stack layout) in the exception handler are the same as in the bit protected by the exception handler. Prior to this patch there were a few bugs. 1) The constant mp_const_MemoryError_obj was being preloaded to a specific location on the stack at the start of the function. But this location on the stack was being overwritten in the opcode loop (since it didn't think that variable would ever be referenced again), and so when an exception occurred, the variable holding the address of MemoryError was corrupt. 2) The FOR_ITER opcode detection in the exception handler used sp, which may or may not contain the right value coming out of the main opcode loop. With this patch there is a clear separation of variables used in the opcode loop and in the exception handler (should fix issue (2) above). Furthermore, nlr_raise is no longer used in the opcode loop. Instead, it jumps directly into the exception handler. This tells the C compiler more about the possible code flow, and means that it should have the same stack layout for the exception handler. This should fix issue (1) above. Indeed, the generated (ARM) assembler has been checked explicitly, and with 'goto exception_handler', the problem with &MemoryError is fixed. This may now fix problems with rge-sm, and probably many other subtle bugs yet to show themselves. Incidentally, rge-sm now passes on pyboard (with a reduced range of integration)! Main lesson: nlr is tricky. Don't use nlr_push unless you know what you are doing! Luckily, it's not used in many places. Using nlr_raise/jump is fine.
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// variables that are visible to the exception handler (declared volatile)
volatile bool currently_in_except_block = MP_TAGPTR_TAG(code_state->exc_sp); // 0 or 1, to detect nested exceptions
mp_exc_stack_t *volatile exc_sp = MP_TAGPTR_PTR(code_state->exc_sp); // stack grows up, exc_sp points to top of stack
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// outer exception handling loop
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for (;;) {
py: Tidy up variables in VM, probably fixes subtle bugs. Things get tricky when using the nlr code to catch exceptions. Need to ensure that the variables (stack layout) in the exception handler are the same as in the bit protected by the exception handler. Prior to this patch there were a few bugs. 1) The constant mp_const_MemoryError_obj was being preloaded to a specific location on the stack at the start of the function. But this location on the stack was being overwritten in the opcode loop (since it didn't think that variable would ever be referenced again), and so when an exception occurred, the variable holding the address of MemoryError was corrupt. 2) The FOR_ITER opcode detection in the exception handler used sp, which may or may not contain the right value coming out of the main opcode loop. With this patch there is a clear separation of variables used in the opcode loop and in the exception handler (should fix issue (2) above). Furthermore, nlr_raise is no longer used in the opcode loop. Instead, it jumps directly into the exception handler. This tells the C compiler more about the possible code flow, and means that it should have the same stack layout for the exception handler. This should fix issue (1) above. Indeed, the generated (ARM) assembler has been checked explicitly, and with 'goto exception_handler', the problem with &MemoryError is fixed. This may now fix problems with rge-sm, and probably many other subtle bugs yet to show themselves. Incidentally, rge-sm now passes on pyboard (with a reduced range of integration)! Main lesson: nlr is tricky. Don't use nlr_push unless you know what you are doing! Luckily, it's not used in many places. Using nlr_raise/jump is fine.
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nlr_buf_t nlr;
outer_dispatch_loop:
if (nlr_push(&nlr) == 0) {
py: Tidy up variables in VM, probably fixes subtle bugs. Things get tricky when using the nlr code to catch exceptions. Need to ensure that the variables (stack layout) in the exception handler are the same as in the bit protected by the exception handler. Prior to this patch there were a few bugs. 1) The constant mp_const_MemoryError_obj was being preloaded to a specific location on the stack at the start of the function. But this location on the stack was being overwritten in the opcode loop (since it didn't think that variable would ever be referenced again), and so when an exception occurred, the variable holding the address of MemoryError was corrupt. 2) The FOR_ITER opcode detection in the exception handler used sp, which may or may not contain the right value coming out of the main opcode loop. With this patch there is a clear separation of variables used in the opcode loop and in the exception handler (should fix issue (2) above). Furthermore, nlr_raise is no longer used in the opcode loop. Instead, it jumps directly into the exception handler. This tells the C compiler more about the possible code flow, and means that it should have the same stack layout for the exception handler. This should fix issue (1) above. Indeed, the generated (ARM) assembler has been checked explicitly, and with 'goto exception_handler', the problem with &MemoryError is fixed. This may now fix problems with rge-sm, and probably many other subtle bugs yet to show themselves. Incidentally, rge-sm now passes on pyboard (with a reduced range of integration)! Main lesson: nlr is tricky. Don't use nlr_push unless you know what you are doing! Luckily, it's not used in many places. Using nlr_raise/jump is fine.
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// local variables that are not visible to the exception handler
const byte *ip = code_state->ip;
mp_obj_t *sp = code_state->sp;
mp_uint_t unum;
mp_obj_t obj_shared;
py: Tidy up variables in VM, probably fixes subtle bugs. Things get tricky when using the nlr code to catch exceptions. Need to ensure that the variables (stack layout) in the exception handler are the same as in the bit protected by the exception handler. Prior to this patch there were a few bugs. 1) The constant mp_const_MemoryError_obj was being preloaded to a specific location on the stack at the start of the function. But this location on the stack was being overwritten in the opcode loop (since it didn't think that variable would ever be referenced again), and so when an exception occurred, the variable holding the address of MemoryError was corrupt. 2) The FOR_ITER opcode detection in the exception handler used sp, which may or may not contain the right value coming out of the main opcode loop. With this patch there is a clear separation of variables used in the opcode loop and in the exception handler (should fix issue (2) above). Furthermore, nlr_raise is no longer used in the opcode loop. Instead, it jumps directly into the exception handler. This tells the C compiler more about the possible code flow, and means that it should have the same stack layout for the exception handler. This should fix issue (1) above. Indeed, the generated (ARM) assembler has been checked explicitly, and with 'goto exception_handler', the problem with &MemoryError is fixed. This may now fix problems with rge-sm, and probably many other subtle bugs yet to show themselves. Incidentally, rge-sm now passes on pyboard (with a reduced range of integration)! Main lesson: nlr is tricky. Don't use nlr_push unless you know what you are doing! Luckily, it's not used in many places. Using nlr_raise/jump is fine.
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// If we have exception to inject, now that we finish setting up
// execution context, raise it. This works as if RAISE_VARARGS
// bytecode was executed.
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// Injecting exc into yield from generator is a special case,
// handled by MP_BC_YIELD_FROM itself
if (inject_exc != MP_OBJ_NULL && *ip != MP_BC_YIELD_FROM) {
mp_obj_t exc = inject_exc;
inject_exc = MP_OBJ_NULL;
exc = mp_make_raise_obj(exc);
RAISE(exc);
}
py: Tidy up variables in VM, probably fixes subtle bugs. Things get tricky when using the nlr code to catch exceptions. Need to ensure that the variables (stack layout) in the exception handler are the same as in the bit protected by the exception handler. Prior to this patch there were a few bugs. 1) The constant mp_const_MemoryError_obj was being preloaded to a specific location on the stack at the start of the function. But this location on the stack was being overwritten in the opcode loop (since it didn't think that variable would ever be referenced again), and so when an exception occurred, the variable holding the address of MemoryError was corrupt. 2) The FOR_ITER opcode detection in the exception handler used sp, which may or may not contain the right value coming out of the main opcode loop. With this patch there is a clear separation of variables used in the opcode loop and in the exception handler (should fix issue (2) above). Furthermore, nlr_raise is no longer used in the opcode loop. Instead, it jumps directly into the exception handler. This tells the C compiler more about the possible code flow, and means that it should have the same stack layout for the exception handler. This should fix issue (1) above. Indeed, the generated (ARM) assembler has been checked explicitly, and with 'goto exception_handler', the problem with &MemoryError is fixed. This may now fix problems with rge-sm, and probably many other subtle bugs yet to show themselves. Incidentally, rge-sm now passes on pyboard (with a reduced range of integration)! Main lesson: nlr is tricky. Don't use nlr_push unless you know what you are doing! Luckily, it's not used in many places. Using nlr_raise/jump is fine.
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// loop to execute byte code
for (;;) {
dispatch_loop:
#if MICROPY_OPT_COMPUTED_GOTO
DISPATCH();
#else
TRACE(ip);
code_state->ip = ip;
switch (*ip++) {
#endif
ENTRY(MP_BC_LOAD_CONST_FALSE):
PUSH(mp_const_false);
DISPATCH();
ENTRY(MP_BC_LOAD_CONST_NONE):
PUSH(mp_const_none);
DISPATCH();
ENTRY(MP_BC_LOAD_CONST_TRUE):
PUSH(mp_const_true);
DISPATCH();
ENTRY(MP_BC_LOAD_CONST_ELLIPSIS):
PUSH((mp_obj_t)&mp_const_ellipsis_obj);
DISPATCH();
ENTRY(MP_BC_LOAD_CONST_SMALL_INT): {
mp_int_t num = 0;
if ((ip[0] & 0x40) != 0) {
// Number is negative
num--;
}
do {
num = (num << 7) | (*ip & 0x7f);
} while ((*ip++ & 0x80) != 0);
PUSH(MP_OBJ_NEW_SMALL_INT(num));
DISPATCH();
}
ENTRY(MP_BC_LOAD_CONST_INT): {
DECODE_QSTR;
PUSH(mp_load_const_int(qst));
DISPATCH();
}
ENTRY(MP_BC_LOAD_CONST_DEC): {
DECODE_QSTR;
PUSH(mp_load_const_dec(qst));
DISPATCH();
}
ENTRY(MP_BC_LOAD_CONST_BYTES): {
DECODE_QSTR;
PUSH(mp_load_const_bytes(qst));
DISPATCH();
}
ENTRY(MP_BC_LOAD_CONST_STRING): {
DECODE_QSTR;
PUSH(mp_load_const_str(qst));
DISPATCH();
}
ENTRY(MP_BC_LOAD_NULL):
PUSH(MP_OBJ_NULL);
DISPATCH();
ENTRY(MP_BC_LOAD_FAST_0):
obj_shared = fastn[0];
goto load_check;
ENTRY(MP_BC_LOAD_FAST_1):
obj_shared = fastn[-1];
goto load_check;
ENTRY(MP_BC_LOAD_FAST_2):
obj_shared = fastn[-2];
goto load_check;
ENTRY(MP_BC_LOAD_FAST_N):
DECODE_UINT;
obj_shared = fastn[-unum];
load_check:
if (obj_shared == MP_OBJ_NULL) {
local_name_error: {
mp_obj_t obj = mp_obj_new_exception_msg(&mp_type_NameError, "local variable referenced before assignment");
RAISE(obj);
}
}
PUSH(obj_shared);
DISPATCH();
ENTRY(MP_BC_LOAD_DEREF):
DECODE_UINT;
obj_shared = mp_obj_cell_get(fastn[-unum]);
goto load_check;
ENTRY(MP_BC_LOAD_NAME): {
DECODE_QSTR;
PUSH(mp_load_name(qst));
DISPATCH();
}
ENTRY(MP_BC_LOAD_GLOBAL): {
DECODE_QSTR;
PUSH(mp_load_global(qst));
DISPATCH();
}
ENTRY(MP_BC_LOAD_ATTR): {
DECODE_QSTR;
SET_TOP(mp_load_attr(TOP(), qst));
DISPATCH();
}
ENTRY(MP_BC_LOAD_METHOD): {
DECODE_QSTR;
mp_load_method(*sp, qst, sp);
sp += 1;
DISPATCH();
}
ENTRY(MP_BC_LOAD_BUILD_CLASS):
PUSH(mp_load_build_class());
DISPATCH();
ENTRY(MP_BC_LOAD_SUBSCR): {
mp_obj_t index = POP();
SET_TOP(mp_obj_subscr(TOP(), index, MP_OBJ_SENTINEL));
DISPATCH();
}
ENTRY(MP_BC_STORE_FAST_0):
fastn[0] = POP();
DISPATCH();
ENTRY(MP_BC_STORE_FAST_1):
fastn[-1] = POP();
DISPATCH();
ENTRY(MP_BC_STORE_FAST_2):
fastn[-2] = POP();
DISPATCH();
ENTRY(MP_BC_STORE_FAST_N):
DECODE_UINT;
fastn[-unum] = POP();
DISPATCH();
ENTRY(MP_BC_STORE_DEREF):
DECODE_UINT;
mp_obj_cell_set(fastn[-unum], POP());
DISPATCH();
ENTRY(MP_BC_STORE_NAME): {
DECODE_QSTR;
mp_store_name(qst, POP());
DISPATCH();
}
ENTRY(MP_BC_STORE_GLOBAL): {
DECODE_QSTR;
mp_store_global(qst, POP());
DISPATCH();
}
ENTRY(MP_BC_STORE_ATTR): {
DECODE_QSTR;
mp_store_attr(sp[0], qst, sp[-1]);
sp -= 2;
DISPATCH();
}
ENTRY(MP_BC_STORE_SUBSCR):
mp_obj_subscr(sp[-1], sp[0], sp[-2]);
sp -= 3;
DISPATCH();
ENTRY(MP_BC_DELETE_FAST):
DECODE_UINT;
if (fastn[-unum] == MP_OBJ_NULL) {
goto local_name_error;
}
fastn[-unum] = MP_OBJ_NULL;
DISPATCH();
ENTRY(MP_BC_DELETE_DEREF):
DECODE_UINT;
if (mp_obj_cell_get(fastn[-unum]) == MP_OBJ_NULL) {
goto local_name_error;
}
mp_obj_cell_set(fastn[-unum], MP_OBJ_NULL);
DISPATCH();
ENTRY(MP_BC_DELETE_NAME): {
DECODE_QSTR;
mp_delete_name(qst);
DISPATCH();
}
ENTRY(MP_BC_DELETE_GLOBAL): {
DECODE_QSTR;
mp_delete_global(qst);
DISPATCH();
}
ENTRY(MP_BC_DUP_TOP): {
mp_obj_t top = TOP();
PUSH(top);
DISPATCH();
}
ENTRY(MP_BC_DUP_TOP_TWO):
sp += 2;
sp[0] = sp[-2];
sp[-1] = sp[-3];
DISPATCH();
ENTRY(MP_BC_POP_TOP):
sp -= 1;
DISPATCH();
ENTRY(MP_BC_ROT_TWO): {
mp_obj_t top = sp[0];
sp[0] = sp[-1];
sp[-1] = top;
DISPATCH();
}
ENTRY(MP_BC_ROT_THREE): {
mp_obj_t top = sp[0];
sp[0] = sp[-1];
sp[-1] = sp[-2];
sp[-2] = top;
DISPATCH();
}
ENTRY(MP_BC_JUMP):
DECODE_SLABEL;
ip += unum;
DISPATCH();
ENTRY(MP_BC_POP_JUMP_IF_TRUE):
DECODE_SLABEL;
if (mp_obj_is_true(POP())) {
ip += unum;
}
DISPATCH();
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ENTRY(MP_BC_POP_JUMP_IF_FALSE):
DECODE_SLABEL;
if (!mp_obj_is_true(POP())) {
ip += unum;
}
DISPATCH();
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ENTRY(MP_BC_JUMP_IF_TRUE_OR_POP):
DECODE_SLABEL;
if (mp_obj_is_true(TOP())) {
ip += unum;
} else {
sp--;
}
DISPATCH();
ENTRY(MP_BC_JUMP_IF_FALSE_OR_POP):
DECODE_SLABEL;
if (mp_obj_is_true(TOP())) {
sp--;
} else {
ip += unum;
}
DISPATCH();
ENTRY(MP_BC_SETUP_WITH): {
mp_obj_t obj = TOP();
SET_TOP(mp_load_attr(obj, MP_QSTR___exit__));
mp_load_method(obj, MP_QSTR___enter__, sp + 1);
mp_obj_t ret = mp_call_method_n_kw(0, 0, sp + 1);
PUSH_EXC_BLOCK();
PUSH(ret);
DISPATCH();
}
ENTRY(MP_BC_WITH_CLEANUP): {
// Arriving here, there's "exception control block" on top of stack,
// and __exit__ bound method underneath it. Bytecode calls __exit__,
// and "deletes" it off stack, shifting "exception control block"
// to its place.
static const mp_obj_t no_exc[] = {mp_const_none, mp_const_none, mp_const_none};
if (TOP() == mp_const_none) {
sp--;
mp_obj_t obj = TOP();
SET_TOP(mp_const_none);
mp_call_function_n_kw(obj, 3, 0, no_exc);
} else if (MP_OBJ_IS_SMALL_INT(TOP())) {
mp_obj_t cause = POP();
switch (MP_OBJ_SMALL_INT_VALUE(cause)) {
case UNWIND_RETURN: {
mp_obj_t retval = POP();
mp_call_function_n_kw(TOP(), 3, 0, no_exc);
SET_TOP(retval);
PUSH(cause);
break;
}
case UNWIND_JUMP: {
mp_call_function_n_kw(sp[-2], 3, 0, no_exc);
// Pop __exit__ boundmethod at sp[-2]
sp[-2] = sp[-1];
sp[-1] = sp[0];
SET_TOP(cause);
break;
}
default:
assert(0);
}
} else if (mp_obj_is_exception_type(TOP())) {
mp_obj_t args[3] = {sp[0], sp[-1], sp[-2]};
mp_obj_t ret_value = mp_call_function_n_kw(sp[-3], 3, 0, args);
// Pop __exit__ boundmethod at sp[-3]
// TODO: Once semantics is proven, optimize for case when ret_value == True
sp[-3] = sp[-2];
sp[-2] = sp[-1];
sp[-1] = sp[0];
sp--;
if (mp_obj_is_true(ret_value)) {
// This is what CPython does
//PUSH(MP_OBJ_NEW_SMALL_INT(UNWIND_SILENCED));
// But what we need to do is - pop exception from value stack...
sp -= 3;
// ... pop "with" exception handler, and signal END_FINALLY
// to just execute finally handler normally (by pushing None
// on value stack)
assert(exc_sp >= exc_stack);
assert(exc_sp->opcode == MP_BC_SETUP_WITH);
POP_EXC_BLOCK();
PUSH(mp_const_none);
}
} else {
assert(0);
}
DISPATCH();
}
ENTRY(MP_BC_UNWIND_JUMP):
DECODE_SLABEL;
PUSH((void*)(ip + unum)); // push destination ip for jump
PUSH((void*)(mp_uint_t)(*ip)); // push number of exception handlers to unwind (0x80 bit set if we also need to pop stack)
unwind_jump:
unum = (mp_uint_t)POP(); // get number of exception handlers to unwind
while ((unum & 0x7f) > 0) {
unum -= 1;
assert(exc_sp >= exc_stack);
if (exc_sp->opcode == MP_BC_SETUP_FINALLY || exc_sp->opcode == MP_BC_SETUP_WITH) {
// We're going to run "finally" code as a coroutine
// (not calling it recursively). Set up a sentinel
// on a stack so it can return back to us when it is
// done (when END_FINALLY reached).
PUSH((void*)unum); // push number of exception handlers left to unwind
PUSH(MP_OBJ_NEW_SMALL_INT(UNWIND_JUMP)); // push sentinel
ip = exc_sp->handler; // get exception handler byte code address
exc_sp--; // pop exception handler
goto dispatch_loop; // run the exception handler
}
exc_sp--;
}
ip = (const byte*)POP(); // pop destination ip for jump
if (unum != 0) {
sp--;
}
DISPATCH();
// matched against: POP_BLOCK or POP_EXCEPT (anything else?)
ENTRY(MP_BC_SETUP_EXCEPT):
ENTRY(MP_BC_SETUP_FINALLY):
PUSH_EXC_BLOCK();
DISPATCH();
ENTRY(MP_BC_END_FINALLY):
// not fully implemented
// if TOS is an exception, reraises the exception (3 values on TOS)
// if TOS is None, just pops it and continues
// if TOS is an integer, does something else
// else error
if (mp_obj_is_exception_type(TOP())) {
py: Tidy up variables in VM, probably fixes subtle bugs. Things get tricky when using the nlr code to catch exceptions. Need to ensure that the variables (stack layout) in the exception handler are the same as in the bit protected by the exception handler. Prior to this patch there were a few bugs. 1) The constant mp_const_MemoryError_obj was being preloaded to a specific location on the stack at the start of the function. But this location on the stack was being overwritten in the opcode loop (since it didn't think that variable would ever be referenced again), and so when an exception occurred, the variable holding the address of MemoryError was corrupt. 2) The FOR_ITER opcode detection in the exception handler used sp, which may or may not contain the right value coming out of the main opcode loop. With this patch there is a clear separation of variables used in the opcode loop and in the exception handler (should fix issue (2) above). Furthermore, nlr_raise is no longer used in the opcode loop. Instead, it jumps directly into the exception handler. This tells the C compiler more about the possible code flow, and means that it should have the same stack layout for the exception handler. This should fix issue (1) above. Indeed, the generated (ARM) assembler has been checked explicitly, and with 'goto exception_handler', the problem with &MemoryError is fixed. This may now fix problems with rge-sm, and probably many other subtle bugs yet to show themselves. Incidentally, rge-sm now passes on pyboard (with a reduced range of integration)! Main lesson: nlr is tricky. Don't use nlr_push unless you know what you are doing! Luckily, it's not used in many places. Using nlr_raise/jump is fine.
2014-04-17 11:50:23 -04:00
RAISE(sp[-1]);
}
if (TOP() == mp_const_none) {
sp--;
} else if (MP_OBJ_IS_SMALL_INT(TOP())) {
// We finished "finally" coroutine and now dispatch back
// to our caller, based on TOS value
mp_unwind_reason_t reason = MP_OBJ_SMALL_INT_VALUE(POP());
switch (reason) {
case UNWIND_RETURN:
goto unwind_return;
case UNWIND_JUMP:
goto unwind_jump;
}
assert(0);
} else {
assert(0);
}
DISPATCH();
ENTRY(MP_BC_GET_ITER):
SET_TOP(mp_getiter(TOP()));
DISPATCH();
ENTRY(MP_BC_FOR_ITER): {
DECODE_ULABEL; // the jump offset if iteration finishes; for labels are always forward
code_state->sp = sp;
assert(TOP());
mp_obj_t value = mp_iternext_allow_raise(TOP());
if (value == MP_OBJ_STOP_ITERATION) {
--sp; // pop the exhausted iterator
ip += unum; // jump to after for-block
} else {
PUSH(value); // push the next iteration value
}
DISPATCH();
}
// matched against: SETUP_EXCEPT, SETUP_FINALLY, SETUP_WITH
ENTRY(MP_BC_POP_BLOCK):
// we are exiting an exception handler, so pop the last one of the exception-stack
assert(exc_sp >= exc_stack);
POP_EXC_BLOCK();
DISPATCH();
// matched against: SETUP_EXCEPT
ENTRY(MP_BC_POP_EXCEPT):
// TODO need to work out how blocks work etc
// pops block, checks it's an exception block, and restores the stack, saving the 3 exception values to local threadstate
assert(exc_sp >= exc_stack);
assert(currently_in_except_block);
//sp = (mp_obj_t*)(*exc_sp--);
//exc_sp--; // discard ip
POP_EXC_BLOCK();
//sp -= 3; // pop 3 exception values
DISPATCH();
ENTRY(MP_BC_NOT):
if (TOP() == mp_const_true) {
SET_TOP(mp_const_false);
} else {
SET_TOP(mp_const_true);
}
DISPATCH();
ENTRY(MP_BC_UNARY_OP):
unum = *ip++;
SET_TOP(mp_unary_op(unum, TOP()));
DISPATCH();
ENTRY(MP_BC_BINARY_OP): {
unum = *ip++;
mp_obj_t rhs = POP();
mp_obj_t lhs = TOP();
SET_TOP(mp_binary_op(unum, lhs, rhs));
DISPATCH();
}
ENTRY(MP_BC_BUILD_TUPLE):
DECODE_UINT;
sp -= unum - 1;
SET_TOP(mp_obj_new_tuple(unum, sp));
DISPATCH();
ENTRY(MP_BC_BUILD_LIST):
DECODE_UINT;
sp -= unum - 1;
SET_TOP(mp_obj_new_list(unum, sp));
DISPATCH();
ENTRY(MP_BC_LIST_APPEND):
DECODE_UINT;
// I think it's guaranteed by the compiler that sp[unum] is a list
mp_obj_list_append(sp[-unum], sp[0]);
sp--;
DISPATCH();
ENTRY(MP_BC_BUILD_MAP):
DECODE_UINT;
PUSH(mp_obj_new_dict(unum));
DISPATCH();
ENTRY(MP_BC_STORE_MAP):
sp -= 2;
mp_obj_dict_store(sp[0], sp[2], sp[1]);
DISPATCH();
ENTRY(MP_BC_MAP_ADD):
DECODE_UINT;
// I think it's guaranteed by the compiler that sp[-unum - 1] is a map
mp_obj_dict_store(sp[-unum - 1], sp[0], sp[-1]);
sp -= 2;
DISPATCH();
#if MICROPY_PY_BUILTINS_SET
ENTRY(MP_BC_BUILD_SET):
DECODE_UINT;
sp -= unum - 1;
SET_TOP(mp_obj_new_set(unum, sp));
DISPATCH();
ENTRY(MP_BC_SET_ADD):
DECODE_UINT;
// I think it's guaranteed by the compiler that sp[-unum] is a set
mp_obj_set_store(sp[-unum], sp[0]);
sp--;
DISPATCH();
#endif
2013-10-16 15:57:49 -04:00
#if MICROPY_PY_BUILTINS_SLICE
ENTRY(MP_BC_BUILD_SLICE):
DECODE_UINT;
if (unum == 2) {
mp_obj_t stop = POP();
mp_obj_t start = TOP();
SET_TOP(mp_obj_new_slice(start, stop, mp_const_none));
} else {
mp_obj_t step = POP();
mp_obj_t stop = POP();
mp_obj_t start = TOP();
SET_TOP(mp_obj_new_slice(start, stop, step));
}
DISPATCH();
#endif
ENTRY(MP_BC_UNPACK_SEQUENCE):
DECODE_UINT;
mp_unpack_sequence(sp[0], unum, sp);
sp += unum - 1;
DISPATCH();
ENTRY(MP_BC_UNPACK_EX):
DECODE_UINT;
mp_unpack_ex(sp[0], unum, sp);
sp += (unum & 0xff) + ((unum >> 8) & 0xff);
DISPATCH();
ENTRY(MP_BC_MAKE_FUNCTION):
DECODE_PTR;
PUSH(mp_make_function_from_raw_code((mp_raw_code_t*)unum, MP_OBJ_NULL, MP_OBJ_NULL));
DISPATCH();
ENTRY(MP_BC_MAKE_FUNCTION_DEFARGS): {
DECODE_PTR;
// Stack layout: def_tuple def_dict <- TOS
mp_obj_t def_dict = POP();
SET_TOP(mp_make_function_from_raw_code((mp_raw_code_t*)unum, TOP(), def_dict));
DISPATCH();
}
ENTRY(MP_BC_MAKE_CLOSURE): {
DECODE_PTR;
mp_uint_t n_closed_over = *ip++;
// Stack layout: closed_overs <- TOS
sp -= n_closed_over - 1;
SET_TOP(mp_make_closure_from_raw_code((mp_raw_code_t*)unum, n_closed_over, sp));
DISPATCH();
}
ENTRY(MP_BC_MAKE_CLOSURE_DEFARGS): {
DECODE_PTR;
mp_uint_t n_closed_over = *ip++;
// Stack layout: def_tuple def_dict closed_overs <- TOS
sp -= 2 + n_closed_over - 1;
SET_TOP(mp_make_closure_from_raw_code((mp_raw_code_t*)unum, 0x100 | n_closed_over, sp));
DISPATCH();
}
ENTRY(MP_BC_CALL_FUNCTION):
DECODE_UINT;
// unum & 0xff == n_positional
// (unum >> 8) & 0xff == n_keyword
sp -= (unum & 0xff) + ((unum >> 7) & 0x1fe);
SET_TOP(mp_call_function_n_kw(*sp, unum & 0xff, (unum >> 8) & 0xff, sp + 1));
DISPATCH();
ENTRY(MP_BC_CALL_FUNCTION_VAR_KW):
DECODE_UINT;
// unum & 0xff == n_positional
// (unum >> 8) & 0xff == n_keyword
// We have folowing stack layout here:
// fun arg0 arg1 ... kw0 val0 kw1 val1 ... seq dict <- TOS
sp -= (unum & 0xff) + ((unum >> 7) & 0x1fe) + 2;
SET_TOP(mp_call_method_n_kw_var(false, unum, sp));
DISPATCH();
ENTRY(MP_BC_CALL_METHOD):
DECODE_UINT;
// unum & 0xff == n_positional
// (unum >> 8) & 0xff == n_keyword
sp -= (unum & 0xff) + ((unum >> 7) & 0x1fe) + 1;
SET_TOP(mp_call_method_n_kw(unum & 0xff, (unum >> 8) & 0xff, sp));
DISPATCH();
ENTRY(MP_BC_CALL_METHOD_VAR_KW):
DECODE_UINT;
// unum & 0xff == n_positional
// (unum >> 8) & 0xff == n_keyword
// We have folowing stack layout here:
// fun self arg0 arg1 ... kw0 val0 kw1 val1 ... seq dict <- TOS
sp -= (unum & 0xff) + ((unum >> 7) & 0x1fe) + 3;
SET_TOP(mp_call_method_n_kw_var(true, unum, sp));
DISPATCH();
ENTRY(MP_BC_RETURN_VALUE):
unwind_return:
while (exc_sp >= exc_stack) {
if (exc_sp->opcode == MP_BC_SETUP_FINALLY || exc_sp->opcode == MP_BC_SETUP_WITH) {
// We're going to run "finally" code as a coroutine
// (not calling it recursively). Set up a sentinel
// on a stack so it can return back to us when it is
// done (when END_FINALLY reached).
PUSH(MP_OBJ_NEW_SMALL_INT(UNWIND_RETURN));
ip = exc_sp->handler;
// We don't need to do anything with sp, finally is just
// syntactic sugar for sequential execution??
// sp =
exc_sp--;
goto dispatch_loop;
}
exc_sp--;
}
nlr_pop();
code_state->sp = sp;
assert(exc_sp == exc_stack - 1);
return MP_VM_RETURN_NORMAL;
ENTRY(MP_BC_RAISE_VARARGS): {
unum = *ip++;
mp_obj_t obj;
assert(unum <= 1);
if (unum == 0) {
// search for the inner-most previous exception, to reraise it
obj = MP_OBJ_NULL;
for (mp_exc_stack_t *e = exc_sp; e >= exc_stack; e--) {
if (e->prev_exc != MP_OBJ_NULL) {
obj = e->prev_exc;
break;
}
}
if (obj == MP_OBJ_NULL) {
obj = mp_obj_new_exception_msg(&mp_type_RuntimeError, "No active exception to reraise");
RAISE(obj);
}
} else {
obj = POP();
}
obj = mp_make_raise_obj(obj);
RAISE(obj);
}
ENTRY(MP_BC_YIELD_VALUE):
2014-03-26 11:36:12 -04:00
yield:
nlr_pop();
code_state->ip = ip;
code_state->sp = sp;
code_state->exc_sp = MP_TAGPTR_MAKE(exc_sp, currently_in_except_block);
return MP_VM_RETURN_YIELD;
ENTRY(MP_BC_YIELD_FROM): {
2014-03-26 11:36:12 -04:00
//#define EXC_MATCH(exc, type) MP_OBJ_IS_TYPE(exc, type)
#define EXC_MATCH(exc, type) mp_obj_exception_match(exc, type)
py: Tidy up variables in VM, probably fixes subtle bugs. Things get tricky when using the nlr code to catch exceptions. Need to ensure that the variables (stack layout) in the exception handler are the same as in the bit protected by the exception handler. Prior to this patch there were a few bugs. 1) The constant mp_const_MemoryError_obj was being preloaded to a specific location on the stack at the start of the function. But this location on the stack was being overwritten in the opcode loop (since it didn't think that variable would ever be referenced again), and so when an exception occurred, the variable holding the address of MemoryError was corrupt. 2) The FOR_ITER opcode detection in the exception handler used sp, which may or may not contain the right value coming out of the main opcode loop. With this patch there is a clear separation of variables used in the opcode loop and in the exception handler (should fix issue (2) above). Furthermore, nlr_raise is no longer used in the opcode loop. Instead, it jumps directly into the exception handler. This tells the C compiler more about the possible code flow, and means that it should have the same stack layout for the exception handler. This should fix issue (1) above. Indeed, the generated (ARM) assembler has been checked explicitly, and with 'goto exception_handler', the problem with &MemoryError is fixed. This may now fix problems with rge-sm, and probably many other subtle bugs yet to show themselves. Incidentally, rge-sm now passes on pyboard (with a reduced range of integration)! Main lesson: nlr is tricky. Don't use nlr_push unless you know what you are doing! Luckily, it's not used in many places. Using nlr_raise/jump is fine.
2014-04-17 11:50:23 -04:00
#define GENERATOR_EXIT_IF_NEEDED(t) if (t != MP_OBJ_NULL && EXC_MATCH(t, &mp_type_GeneratorExit)) { RAISE(t); }
mp_vm_return_kind_t ret_kind;
mp_obj_t send_value = POP();
mp_obj_t t_exc = MP_OBJ_NULL;
mp_obj_t ret_value;
if (inject_exc != MP_OBJ_NULL) {
t_exc = inject_exc;
inject_exc = MP_OBJ_NULL;
ret_kind = mp_resume(TOP(), MP_OBJ_NULL, t_exc, &ret_value);
} else {
ret_kind = mp_resume(TOP(), send_value, MP_OBJ_NULL, &ret_value);
}
2014-03-26 11:36:12 -04:00
if (ret_kind == MP_VM_RETURN_YIELD) {
ip--;
PUSH(ret_value);
goto yield;
}
if (ret_kind == MP_VM_RETURN_NORMAL) {
// Pop exhausted gen
sp--;
if (ret_value == MP_OBJ_NULL) {
// Optimize StopIteration
// TODO: get StopIteration's value
PUSH(mp_const_none);
} else {
PUSH(ret_value);
2014-03-26 11:36:12 -04:00
}
// If we injected GeneratorExit downstream, then even
// if it was swallowed, we re-raise GeneratorExit
GENERATOR_EXIT_IF_NEEDED(t_exc);
DISPATCH();
}
if (ret_kind == MP_VM_RETURN_EXCEPTION) {
// Pop exhausted gen
sp--;
if (EXC_MATCH(ret_value, &mp_type_StopIteration)) {
PUSH(mp_obj_exception_get_value(ret_value));
// If we injected GeneratorExit downstream, then even
// if it was swallowed, we re-raise GeneratorExit
GENERATOR_EXIT_IF_NEEDED(t_exc);
DISPATCH();
} else {
RAISE(ret_value);
2014-03-26 11:36:12 -04:00
}
}
}
2014-03-26 11:36:12 -04:00
ENTRY(MP_BC_IMPORT_NAME): {
DECODE_QSTR;
mp_obj_t obj = POP();
SET_TOP(mp_import_name(qst, obj, TOP()));
DISPATCH();
}
ENTRY(MP_BC_IMPORT_FROM): {
DECODE_QSTR;
mp_obj_t obj = mp_import_from(TOP(), qst);
PUSH(obj);
DISPATCH();
}
ENTRY(MP_BC_IMPORT_STAR):
mp_import_all(POP());
DISPATCH();
ENTRY_DEFAULT: {
mp_obj_t obj = mp_obj_new_exception_msg(&mp_type_NotImplementedError, "byte code not implemented");
nlr_pop();
fastn[0] = obj;
return MP_VM_RETURN_EXCEPTION;
}
py: Tidy up variables in VM, probably fixes subtle bugs. Things get tricky when using the nlr code to catch exceptions. Need to ensure that the variables (stack layout) in the exception handler are the same as in the bit protected by the exception handler. Prior to this patch there were a few bugs. 1) The constant mp_const_MemoryError_obj was being preloaded to a specific location on the stack at the start of the function. But this location on the stack was being overwritten in the opcode loop (since it didn't think that variable would ever be referenced again), and so when an exception occurred, the variable holding the address of MemoryError was corrupt. 2) The FOR_ITER opcode detection in the exception handler used sp, which may or may not contain the right value coming out of the main opcode loop. With this patch there is a clear separation of variables used in the opcode loop and in the exception handler (should fix issue (2) above). Furthermore, nlr_raise is no longer used in the opcode loop. Instead, it jumps directly into the exception handler. This tells the C compiler more about the possible code flow, and means that it should have the same stack layout for the exception handler. This should fix issue (1) above. Indeed, the generated (ARM) assembler has been checked explicitly, and with 'goto exception_handler', the problem with &MemoryError is fixed. This may now fix problems with rge-sm, and probably many other subtle bugs yet to show themselves. Incidentally, rge-sm now passes on pyboard (with a reduced range of integration)! Main lesson: nlr is tricky. Don't use nlr_push unless you know what you are doing! Luckily, it's not used in many places. Using nlr_raise/jump is fine.
2014-04-17 11:50:23 -04:00
#if !MICROPY_OPT_COMPUTED_GOTO
} // switch
#endif
py: Tidy up variables in VM, probably fixes subtle bugs. Things get tricky when using the nlr code to catch exceptions. Need to ensure that the variables (stack layout) in the exception handler are the same as in the bit protected by the exception handler. Prior to this patch there were a few bugs. 1) The constant mp_const_MemoryError_obj was being preloaded to a specific location on the stack at the start of the function. But this location on the stack was being overwritten in the opcode loop (since it didn't think that variable would ever be referenced again), and so when an exception occurred, the variable holding the address of MemoryError was corrupt. 2) The FOR_ITER opcode detection in the exception handler used sp, which may or may not contain the right value coming out of the main opcode loop. With this patch there is a clear separation of variables used in the opcode loop and in the exception handler (should fix issue (2) above). Furthermore, nlr_raise is no longer used in the opcode loop. Instead, it jumps directly into the exception handler. This tells the C compiler more about the possible code flow, and means that it should have the same stack layout for the exception handler. This should fix issue (1) above. Indeed, the generated (ARM) assembler has been checked explicitly, and with 'goto exception_handler', the problem with &MemoryError is fixed. This may now fix problems with rge-sm, and probably many other subtle bugs yet to show themselves. Incidentally, rge-sm now passes on pyboard (with a reduced range of integration)! Main lesson: nlr is tricky. Don't use nlr_push unless you know what you are doing! Luckily, it's not used in many places. Using nlr_raise/jump is fine.
2014-04-17 11:50:23 -04:00
} // for loop
} else {
py: Tidy up variables in VM, probably fixes subtle bugs. Things get tricky when using the nlr code to catch exceptions. Need to ensure that the variables (stack layout) in the exception handler are the same as in the bit protected by the exception handler. Prior to this patch there were a few bugs. 1) The constant mp_const_MemoryError_obj was being preloaded to a specific location on the stack at the start of the function. But this location on the stack was being overwritten in the opcode loop (since it didn't think that variable would ever be referenced again), and so when an exception occurred, the variable holding the address of MemoryError was corrupt. 2) The FOR_ITER opcode detection in the exception handler used sp, which may or may not contain the right value coming out of the main opcode loop. With this patch there is a clear separation of variables used in the opcode loop and in the exception handler (should fix issue (2) above). Furthermore, nlr_raise is no longer used in the opcode loop. Instead, it jumps directly into the exception handler. This tells the C compiler more about the possible code flow, and means that it should have the same stack layout for the exception handler. This should fix issue (1) above. Indeed, the generated (ARM) assembler has been checked explicitly, and with 'goto exception_handler', the problem with &MemoryError is fixed. This may now fix problems with rge-sm, and probably many other subtle bugs yet to show themselves. Incidentally, rge-sm now passes on pyboard (with a reduced range of integration)! Main lesson: nlr is tricky. Don't use nlr_push unless you know what you are doing! Luckily, it's not used in many places. Using nlr_raise/jump is fine.
2014-04-17 11:50:23 -04:00
exception_handler:
// exception occurred
// check if it's a StopIteration within a for block
if (*code_state->ip == MP_BC_FOR_ITER && mp_obj_is_subclass_fast(mp_obj_get_type(nlr.ret_val), &mp_type_StopIteration)) {
const byte *ip = code_state->ip + 1;
mp_uint_t unum;
DECODE_ULABEL; // the jump offset if iteration finishes; for labels are always forward
code_state->ip = ip + unum; // jump to after for-block
code_state->sp -= 1; // pop the exhausted iterator
goto outer_dispatch_loop; // continue with dispatch loop
}
// set file and line number that the exception occurred at
// TODO: don't set traceback for exceptions re-raised by END_FINALLY.
// But consider how to handle nested exceptions.
// TODO need a better way of not adding traceback to constant objects (right now, just GeneratorExit_obj and MemoryError_obj)
if (mp_obj_is_exception_instance(nlr.ret_val) && nlr.ret_val != &mp_const_GeneratorExit_obj && nlr.ret_val != &mp_const_MemoryError_obj) {
const byte *code_info = code_state->code_info;
mp_uint_t code_info_size = code_info[0] | (code_info[1] << 8) | (code_info[2] << 16) | (code_info[3] << 24);
qstr source_file = code_info[4] | (code_info[5] << 8) | (code_info[6] << 16) | (code_info[7] << 24);
qstr block_name = code_info[8] | (code_info[9] << 8) | (code_info[10] << 16) | (code_info[11] << 24);
mp_uint_t source_line = 0;
mp_uint_t bc = code_state->ip - code_info - code_info_size;
//printf("find %lu %d %d\n", bc, code_info[12], code_info[13]);
const byte* ci = code_info + 12;
if (*ci) {
source_line = 1;
mp_uint_t c;
while ((c = *ci)) {
mp_uint_t b, l;
if ((c & 0x80) == 0) {
// 0b0LLBBBBB encoding
b = c & 0x1f;
l = c >> 5;
ci += 1;
} else {
// 0b1LLLBBBB 0bLLLLLLLL encoding (l's LSB in second byte)
b = c & 0xf;
l = ((c << 4) & 0x700) | ci[1];
ci += 2;
}
if (bc >= b) {
bc -= b;
source_line += l;
} else {
// found source line corresponding to bytecode offset
break;
}
}
}
mp_obj_exception_add_traceback(nlr.ret_val, source_file, source_line, block_name);
}
while (currently_in_except_block) {
// nested exception
assert(exc_sp >= exc_stack);
// TODO make a proper message for nested exception
// at the moment we are just raising the very last exception (the one that caused the nested exception)
// move up to previous exception handler
POP_EXC_BLOCK();
}
if (exc_sp >= exc_stack) {
// set flag to indicate that we are now handling an exception
currently_in_except_block = 1;
// catch exception and pass to byte code
code_state->ip = exc_sp->handler;
py: Tidy up variables in VM, probably fixes subtle bugs. Things get tricky when using the nlr code to catch exceptions. Need to ensure that the variables (stack layout) in the exception handler are the same as in the bit protected by the exception handler. Prior to this patch there were a few bugs. 1) The constant mp_const_MemoryError_obj was being preloaded to a specific location on the stack at the start of the function. But this location on the stack was being overwritten in the opcode loop (since it didn't think that variable would ever be referenced again), and so when an exception occurred, the variable holding the address of MemoryError was corrupt. 2) The FOR_ITER opcode detection in the exception handler used sp, which may or may not contain the right value coming out of the main opcode loop. With this patch there is a clear separation of variables used in the opcode loop and in the exception handler (should fix issue (2) above). Furthermore, nlr_raise is no longer used in the opcode loop. Instead, it jumps directly into the exception handler. This tells the C compiler more about the possible code flow, and means that it should have the same stack layout for the exception handler. This should fix issue (1) above. Indeed, the generated (ARM) assembler has been checked explicitly, and with 'goto exception_handler', the problem with &MemoryError is fixed. This may now fix problems with rge-sm, and probably many other subtle bugs yet to show themselves. Incidentally, rge-sm now passes on pyboard (with a reduced range of integration)! Main lesson: nlr is tricky. Don't use nlr_push unless you know what you are doing! Luckily, it's not used in many places. Using nlr_raise/jump is fine.
2014-04-17 11:50:23 -04:00
mp_obj_t *sp = MP_TAGPTR_PTR(exc_sp->val_sp);
2014-03-29 20:54:48 -04:00
// save this exception in the stack so it can be used in a reraise, if needed
exc_sp->prev_exc = nlr.ret_val;
2013-10-15 18:46:01 -04:00
// push(traceback, exc-val, exc-type)
PUSH(mp_const_none);
2013-10-15 18:46:01 -04:00
PUSH(nlr.ret_val);
PUSH(mp_obj_get_type(nlr.ret_val));
code_state->sp = sp;
} else {
// propagate exception to higher level
// TODO what to do about ip and sp? they don't really make sense at this point
fastn[0] = nlr.ret_val; // must put exception here because sp is invalid
return MP_VM_RETURN_EXCEPTION;
}
2013-10-04 14:53:11 -04:00
}
}
}