Commit cbddb279 authored by Damien George's avatar Damien George
Browse files

py: Implement break/continue from an exception with finally.

Still todo: break/continue from within the finally block itself.
parent a908202d
......@@ -52,8 +52,6 @@
#define MP_BC_JUMP_IF_TRUE_OR_POP (0x48) // rel byte code offset, 16-bit signed, in excess
#define MP_BC_JUMP_IF_FALSE_OR_POP (0x49) // rel byte code offset, 16-bit signed, in excess
#define MP_BC_SETUP_LOOP (0x4a) // rel byte code offset, 16-bit unsigned
#define MP_BC_BREAK_LOOP (0x4b) // rel byte code offset, 16-bit unsigned
#define MP_BC_CONTINUE_LOOP (0x4c) // rel byte code offset, 16-bit unsigned
#define MP_BC_SETUP_WITH (0x4d) // rel byte code offset, 16-bit unsigned
#define MP_BC_WITH_CLEANUP (0x4e)
#define MP_BC_SETUP_EXCEPT (0x4f) // rel byte code offset, 16-bit unsigned
......@@ -63,6 +61,7 @@
#define MP_BC_FOR_ITER (0x53) // rel byte code offset, 16-bit unsigned
#define MP_BC_POP_BLOCK (0x54)
#define MP_BC_POP_EXCEPT (0x55)
#define MP_BC_UNWIND_JUMP (0x56) // rel byte code offset, 16-bit signed, in excess; then a byte
#define MP_BC_UNARY_OP (0x60) // byte
#define MP_BC_BINARY_OP (0x61) // byte
......
......@@ -50,7 +50,8 @@ typedef struct _compiler_t {
int break_label;
int continue_label;
int except_nest_level;
int break_continue_except_level;
int cur_except_level; // increased for SETUP_EXCEPT, SETUP_FINALLY; decreased for POP_BLOCK, POP_EXCEPT
int n_arg_keyword;
bool have_star_arg;
......@@ -1080,18 +1081,14 @@ void compile_break_stmt(compiler_t *comp, mp_parse_node_struct_t *pns) {
if (comp->break_label == 0) {
printf("ERROR: cannot break from here\n");
}
EMIT_ARG(break_loop, comp->break_label);
EMIT_ARG(break_loop, comp->break_label, comp->cur_except_level - comp->break_continue_except_level);
}
void compile_continue_stmt(compiler_t *comp, mp_parse_node_struct_t *pns) {
if (comp->continue_label == 0) {
printf("ERROR: cannot continue from here\n");
}
if (comp->except_nest_level > 0) {
EMIT_ARG(continue_loop, comp->continue_label);
} else {
EMIT_ARG(jump, comp->continue_label);
}
EMIT_ARG(continue_loop, comp->continue_label, comp->cur_except_level - comp->break_continue_except_level);
}
void compile_return_stmt(compiler_t *comp, mp_parse_node_struct_t *pns) {
......@@ -1387,15 +1384,22 @@ void compile_if_stmt(compiler_t *comp, mp_parse_node_struct_t *pns) {
EMIT_ARG(label_assign, l_end);
}
void compile_while_stmt(compiler_t *comp, mp_parse_node_struct_t *pns) {
int old_break_label = comp->break_label;
int old_continue_label = comp->continue_label;
#define START_BREAK_CONTINUE_BLOCK \
int old_break_label = comp->break_label; \
int old_continue_label = comp->continue_label; \
int break_label = comp_next_label(comp); \
int continue_label = comp_next_label(comp); \
comp->break_label = break_label; \
comp->continue_label = continue_label; \
comp->break_continue_except_level = comp->cur_except_level;
int break_label = comp_next_label(comp);
int continue_label = comp_next_label(comp);
#define END_BREAK_CONTINUE_BLOCK \
comp->break_label = old_break_label; \
comp->continue_label = old_continue_label; \
comp->break_continue_except_level = comp->cur_except_level;
comp->break_label = break_label;
comp->continue_label = continue_label;
void compile_while_stmt(compiler_t *comp, mp_parse_node_struct_t *pns) {
START_BREAK_CONTINUE_BLOCK
// compared to CPython, we have an optimised version of while loops
#if MICROPY_EMIT_CPYTHON
......@@ -1423,8 +1427,7 @@ void compile_while_stmt(compiler_t *comp, mp_parse_node_struct_t *pns) {
#endif
// break/continue apply to outer loop (if any) in the else block
comp->break_label = old_break_label;
comp->continue_label = old_continue_label;
END_BREAK_CONTINUE_BLOCK
compile_node(comp, pns->nodes[2]); // else
......@@ -1434,14 +1437,7 @@ void compile_while_stmt(compiler_t *comp, mp_parse_node_struct_t *pns) {
// TODO preload end and step onto stack if they are not constants
// TODO check if step is negative and do opposite test
void compile_for_stmt_optimised_range(compiler_t *comp, mp_parse_node_t pn_var, mp_parse_node_t pn_start, mp_parse_node_t pn_end, mp_parse_node_t pn_step, mp_parse_node_t pn_body, mp_parse_node_t pn_else) {
int old_break_label = comp->break_label;
int old_continue_label = comp->continue_label;
int break_label = comp_next_label(comp);
int continue_label = comp_next_label(comp);
comp->break_label = break_label;
comp->continue_label = continue_label;
START_BREAK_CONTINUE_BLOCK
int top_label = comp_next_label(comp);
int entry_label = comp_next_label(comp);
......@@ -1477,8 +1473,7 @@ void compile_for_stmt_optimised_range(compiler_t *comp, mp_parse_node_t pn_var,
EMIT_ARG(pop_jump_if_true, top_label);
// break/continue apply to outer loop (if any) in the else block
comp->break_label = old_break_label;
comp->continue_label = old_continue_label;
END_BREAK_CONTINUE_BLOCK
compile_node(comp, pn_else);
......@@ -1531,18 +1526,11 @@ void compile_for_stmt(compiler_t *comp, mp_parse_node_struct_t *pns) {
}
#endif
int old_break_label = comp->break_label;
int old_continue_label = comp->continue_label;
START_BREAK_CONTINUE_BLOCK
int for_label = comp_next_label(comp);
int pop_label = comp_next_label(comp);
int end_label = comp_next_label(comp);
int break_label = comp_next_label(comp);
comp->continue_label = for_label;
comp->break_label = break_label;
// I don't think our implementation needs SETUP_LOOP/POP_BLOCK for for-statements
#if MICROPY_EMIT_CPYTHON
EMIT_ARG(setup_loop, end_label);
......@@ -1550,19 +1538,18 @@ void compile_for_stmt(compiler_t *comp, mp_parse_node_struct_t *pns) {
compile_node(comp, pns->nodes[1]); // iterator
EMIT(get_iter);
EMIT_ARG(label_assign, for_label);
EMIT_ARG(label_assign, continue_label);
EMIT_ARG(for_iter, pop_label);
c_assign(comp, pns->nodes[0], ASSIGN_STORE); // variable
compile_node(comp, pns->nodes[2]); // body
if (!EMIT(last_emit_was_return_value)) {
EMIT_ARG(jump, for_label);
EMIT_ARG(jump, continue_label);
}
EMIT_ARG(label_assign, pop_label);
EMIT(for_iter_end);
// break/continue apply to outer loop (if any) in the else block
comp->break_label = old_break_label;
comp->continue_label = old_continue_label;
END_BREAK_CONTINUE_BLOCK
#if MICROPY_EMIT_CPYTHON
EMIT(pop_block);
......@@ -1582,8 +1569,10 @@ void compile_try_except(compiler_t *comp, mp_parse_node_t pn_body, int n_except,
int stack_size = EMIT(get_stack_size);
int l1 = comp_next_label(comp);
int success_label = comp_next_label(comp);
comp->except_nest_level += 1; // for correct handling of continue
EMIT_ARG(setup_except, l1);
comp->cur_except_level += 1;
compile_node(comp, pn_body); // body
EMIT(pop_block);
EMIT_ARG(jump, success_label);
......@@ -1634,6 +1623,7 @@ void compile_try_except(compiler_t *comp, mp_parse_node_t pn_body, int n_except,
if (qstr_exception_local != 0) {
l3 = comp_next_label(comp);
EMIT_ARG(setup_finally, l3);
comp->cur_except_level += 1;
}
compile_node(comp, pns_except->nodes[1]);
if (qstr_exception_local != 0) {
......@@ -1646,15 +1636,18 @@ void compile_try_except(compiler_t *comp, mp_parse_node_t pn_body, int n_except,
EMIT_ARG(load_const_tok, MP_TOKEN_KW_NONE);
EMIT_ARG(store_id, qstr_exception_local);
EMIT_ARG(delete_id, qstr_exception_local);
comp->cur_except_level -= 1;
EMIT(end_finally);
}
EMIT_ARG(jump, l2);
EMIT_ARG(label_assign, end_finally_label);
}
comp->cur_except_level -= 1;
EMIT(end_finally);
EMIT_ARG(label_assign, success_label);
comp->except_nest_level -= 1;
compile_node(comp, pn_else); // else block, can be null
EMIT_ARG(label_assign, l2);
EMIT_ARG(set_stack_size, stack_size);
......@@ -1664,7 +1657,10 @@ void compile_try_finally(compiler_t *comp, mp_parse_node_t pn_body, int n_except
// don't understand how the stack works with exceptions, so we force it to return to the correct value
int stack_size = EMIT(get_stack_size);
int l_finally_block = comp_next_label(comp);
EMIT_ARG(setup_finally, l_finally_block);
comp->cur_except_level += 1;
if (n_except == 0) {
assert(MP_PARSE_NODE_IS_NULL(pn_else));
compile_node(comp, pn_body);
......@@ -1675,7 +1671,10 @@ void compile_try_finally(compiler_t *comp, mp_parse_node_t pn_body, int n_except
EMIT_ARG(load_const_tok, MP_TOKEN_KW_NONE);
EMIT_ARG(label_assign, l_finally_block);
compile_node(comp, pn_finally);
comp->cur_except_level -= 1;
EMIT(end_finally);
EMIT_ARG(set_stack_size, stack_size);
}
......@@ -3056,7 +3055,9 @@ mp_obj_t mp_compile(mp_parse_node_t pn, qstr source_file, bool is_repl) {
comp->break_label = 0;
comp->continue_label = 0;
comp->except_nest_level = 0;
comp->break_continue_except_level = 0;
comp->cur_except_level = 0;
comp->scope_head = NULL;
comp->scope_cur = NULL;
......
......@@ -72,8 +72,8 @@ typedef struct _emit_method_table_t {
void (*jump_if_true_or_pop)(emit_t *emit, int label);
void (*jump_if_false_or_pop)(emit_t *emit, int label);
void (*setup_loop)(emit_t *emit, int label);
void (*break_loop)(emit_t *emit, int label);
void (*continue_loop)(emit_t *emit, int label);
void (*break_loop)(emit_t *emit, int label, int except_depth);
void (*continue_loop)(emit_t *emit, int label, int except_depth);
void (*setup_with)(emit_t *emit, int label);
void (*with_cleanup)(emit_t *emit);
void (*setup_except)(emit_t *emit, int label);
......
......@@ -540,14 +540,14 @@ static void emit_bc_setup_loop(emit_t *emit, int label) {
emit_write_byte_code_byte_unsigned_label(emit, MP_BC_SETUP_LOOP, label);
}
static void emit_bc_break_loop(emit_t *emit, int label) {
emit_pre(emit, 0);
emit_write_byte_code_byte_unsigned_label(emit, MP_BC_BREAK_LOOP, label);
}
static void emit_bc_continue_loop(emit_t *emit, int label) {
emit_pre(emit, 0);
emit_write_byte_code_byte_unsigned_label(emit, MP_BC_CONTINUE_LOOP, label);
static void emit_bc_unwind_jump(emit_t *emit, int label, int except_depth) {
if (except_depth == 0) {
emit_bc_jump(emit, label);
} else {
emit_pre(emit, 0);
emit_write_byte_code_byte_signed_label(emit, MP_BC_UNWIND_JUMP, label);
emit_write_byte_code_byte(emit, except_depth);
}
}
static void emit_bc_setup_with(emit_t *emit, int label) {
......@@ -828,8 +828,8 @@ const emit_method_table_t emit_bc_method_table = {
emit_bc_jump_if_true_or_pop,
emit_bc_jump_if_false_or_pop,
emit_bc_setup_loop,
emit_bc_break_loop,
emit_bc_continue_loop,
emit_bc_unwind_jump,
emit_bc_unwind_jump,
emit_bc_setup_with,
emit_bc_with_cleanup,
emit_bc_setup_except,
......
......@@ -931,10 +931,10 @@ static void emit_native_setup_loop(emit_t *emit, int label) {
emit_post(emit);
}
static void emit_native_break_loop(emit_t *emit, int label) {
static void emit_native_break_loop(emit_t *emit, int label, int except_depth) {
emit_native_jump(emit, label); // TODO properly
}
static void emit_native_continue_loop(emit_t *emit, int label) {
static void emit_native_continue_loop(emit_t *emit, int label, int except_depth) {
assert(0);
}
static void emit_native_setup_with(emit_t *emit, int label) {
......
......@@ -220,14 +220,10 @@ void mp_byte_code_print(const byte *ip, int len) {
printf("SETUP_LOOP " UINT_FMT, ip + unum - ip_start);
break;
case MP_BC_BREAK_LOOP:
DECODE_ULABEL; // loop labels are always forward
printf("BREAK_LOOP " UINT_FMT, ip + unum - ip_start);
break;
case MP_BC_CONTINUE_LOOP:
DECODE_ULABEL; // loop labels are always forward
printf("CONTINUE_LOOP " UINT_FMT, ip + unum - ip_start);
case MP_BC_UNWIND_JUMP:
DECODE_SLABEL;
printf("UNWIND_JUMP " UINT_FMT " %d", ip + unum - ip_start, *ip);
ip += 1;
break;
case MP_BC_SETUP_EXCEPT:
......
......@@ -31,10 +31,11 @@ typedef struct _mp_exc_stack {
} mp_exc_stack;
// 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_BREAK,
UNWIND_CONTINUE,
UNWIND_JUMP,
} mp_unwind_reason_t;
#define DECODE_UINT do { unum = *ip++; if (unum > 127) { unum = ((unum & 0x3f) << 8) | (*ip++); } } while (0)
......@@ -328,16 +329,29 @@ dispatch_loop:
break;
*/
// TODO this might need more sophisticated handling when breaking from within an except
case MP_BC_BREAK_LOOP:
DECODE_ULABEL;
ip += unum;
break;
// TODO this might need more sophisticated handling when breaking from within an except
case MP_BC_CONTINUE_LOOP:
DECODE_ULABEL;
ip += unum;
case MP_BC_UNWIND_JUMP:
DECODE_SLABEL;
PUSH((void*)(ip + unum)); // push destination ip for jump
PUSH((void*)(machine_uint_t)(*ip)); // push number of exception handlers to unwind
unwind_jump:
unum = (machine_uint_t)POP(); // get number of exception handlers to unwind
while (unum > 0) {
unum -= 1;
assert(exc_sp >= exc_stack);
if (exc_sp->opcode == MP_BC_SETUP_FINALLY) {
// 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
break;
// matched against: POP_BLOCK or POP_EXCEPT (anything else?)
......@@ -369,10 +383,8 @@ dispatch_loop:
switch (reason) {
case UNWIND_RETURN:
goto unwind_return;
// TODO
case UNWIND_BREAK:
case UNWIND_CONTINUE:
;
case UNWIND_JUMP:
goto unwind_jump;
}
assert(0);
} else {
......
for i in range(4):
print(i)
try:
while True:
try:
try:
break
finally:
print('finally 1')
finally:
print('finally 2')
print('here')
finally:
print('finnaly 3')
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