py, compiler: Improve stack depth counting.
Much less of a hack now. Hopefully it's correct!
diff --git a/py/compile.c b/py/compile.c
index 9a5534a..ebc144b 100644
--- a/py/compile.c
+++ b/py/compile.c
@@ -1716,11 +1716,7 @@
}
void compile_try_except(compiler_t *comp, mp_parse_node_t pn_body, int n_except, mp_parse_node_t *pn_excepts, mp_parse_node_t pn_else) {
- // this function is a bit of a hack at the moment
- // don't understand how the stack works with exceptions, so we force it to return to the correct value
-
// setup code
- int stack_size = EMIT(get_stack_size);
uint l1 = comp_next_label(comp);
uint success_label = comp_next_label(comp);
@@ -1729,8 +1725,11 @@
compile_node(comp, pn_body); // body
EMIT(pop_block);
- EMIT_ARG(jump, success_label);
- EMIT_ARG(label_assign, l1);
+ EMIT_ARG(jump, success_label); // jump over exception handler
+
+ EMIT_ARG(label_assign, l1); // start of exception handler
+ EMIT_ARG(set_stack_size, EMIT(get_stack_size) + 6); // stack adjust for the 3 exception items, +3 for possible UNWIND_JUMP state
+
uint l2 = comp_next_label(comp);
for (int i = 0; i < n_except; i++) {
@@ -1796,20 +1795,19 @@
}
EMIT_ARG(jump, l2);
EMIT_ARG(label_assign, end_finally_label);
+ EMIT_ARG(set_stack_size, EMIT(get_stack_size) + 3); // stack adjust for the 3 exception items
}
compile_decrease_except_level(comp);
EMIT(end_finally);
+ EMIT_ARG(set_stack_size, EMIT(get_stack_size) - 5); // stack adjust
EMIT_ARG(label_assign, success_label);
compile_node(comp, pn_else); // else block, can be null
EMIT_ARG(label_assign, l2);
- EMIT_ARG(set_stack_size, stack_size);
}
void compile_try_finally(compiler_t *comp, mp_parse_node_t pn_body, int n_except, mp_parse_node_t *pn_except, mp_parse_node_t pn_else, mp_parse_node_t pn_finally) {
- // 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);
uint l_finally_block = comp_next_label(comp);
EMIT_ARG(setup_finally, l_finally_block);
@@ -1817,7 +1815,9 @@
if (n_except == 0) {
assert(MP_PARSE_NODE_IS_NULL(pn_else));
+ EMIT_ARG(set_stack_size, EMIT(get_stack_size) + 3); // stack adjust for possible UNWIND_JUMP state
compile_node(comp, pn_body);
+ EMIT_ARG(set_stack_size, EMIT(get_stack_size) - 3);
} else {
compile_try_except(comp, pn_body, n_except, pn_except, pn_else);
}
@@ -1828,8 +1828,6 @@
compile_decrease_except_level(comp);
EMIT(end_finally);
-
- EMIT_ARG(set_stack_size, stack_size);
}
void compile_try_stmt(compiler_t *comp, mp_parse_node_struct_t *pns) {
@@ -2023,14 +2021,13 @@
assert(MP_PARSE_NODE_IS_STRUCT_KIND(pns->nodes[1], PN_test_if_else));
mp_parse_node_struct_t *pns_test_if_else = (mp_parse_node_struct_t*)pns->nodes[1];
- int stack_size = EMIT(get_stack_size);
uint l_fail = comp_next_label(comp);
uint l_end = comp_next_label(comp);
c_if_cond(comp, pns_test_if_else->nodes[0], false, l_fail); // condition
compile_node(comp, pns->nodes[0]); // success value
EMIT_ARG(jump, l_end);
EMIT_ARG(label_assign, l_fail);
- EMIT_ARG(set_stack_size, stack_size); // force stack size reset
+ EMIT_ARG(set_stack_size, EMIT(get_stack_size) - 1); // adjust stack size
compile_node(comp, pns_test_if_else->nodes[1]); // failure value
EMIT_ARG(label_assign, l_end);
}
@@ -2084,7 +2081,6 @@
}
void compile_comparison(compiler_t *comp, mp_parse_node_struct_t *pns) {
- int stack_size = EMIT(get_stack_size);
int num_nodes = MP_PARSE_NODE_STRUCT_NUM_NODES(pns);
compile_node(comp, pns->nodes[0]);
bool multi = (num_nodes > 3);
@@ -2138,10 +2134,10 @@
uint l_end = comp_next_label(comp);
EMIT_ARG(jump, l_end);
EMIT_ARG(label_assign, l_fail);
+ EMIT_ARG(set_stack_size, EMIT(get_stack_size) + 1);
EMIT(rot_two);
EMIT(pop_top);
EMIT_ARG(label_assign, l_end);
- EMIT_ARG(set_stack_size, stack_size + 1); // force stack size
}
}