diff --git a/py/bc.c b/py/bc.c
index fc1794683949b69325950d080622550a1a4a3c79..2e481bce777485b8ed1f1028fcec2ccd8384b8a0 100644
--- a/py/bc.c
+++ b/py/bc.c
@@ -64,6 +64,14 @@ mp_uint_t mp_decode_uint_value(const byte *ptr) {
return mp_decode_uint(&ptr);
}
+// This function is used to help reduce stack usage at the caller, for the case when
+// the caller doesn't need the actual value and just wants to skip over it.
+const byte *mp_decode_uint_skip(const byte *ptr) {
+ while ((*ptr++) & 0x80) {
+ }
+ return 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
@@ -115,7 +123,7 @@ void mp_setup_code_state(mp_code_state_t *code_state, size_t n_args, size_t n_kw
// get params
size_t n_state = mp_decode_uint(&code_state->ip);
- mp_decode_uint(&code_state->ip); // skip n_exc_stack
+ code_state->ip = mp_decode_uint_skip(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++;
diff --git a/py/bc.h b/py/bc.h
index e8d4286125daa9049b33532b4572f5c1591c099f..88045dc55b728c67810b701b0ecb2e003e2f90bc 100644
--- a/py/bc.h
+++ b/py/bc.h
@@ -92,6 +92,7 @@ typedef struct _mp_code_state_t {
mp_uint_t mp_decode_uint(const byte **ptr);
mp_uint_t mp_decode_uint_value(const byte *ptr);
+const byte *mp_decode_uint_skip(const byte *ptr);
mp_vm_return_kind_t mp_execute_bytecode(mp_code_state_t *code_state, volatile mp_obj_t inject_exc);
mp_code_state_t *mp_obj_fun_bc_prepare_codestate(mp_obj_t func, size_t n_args, size_t n_kw, const mp_obj_t *args);
diff --git a/py/objfun.c b/py/objfun.c
index 08d031c8d8f05fbc015de7f62233ecc8706c717d..9f35891243dc8b26049a893861edafc22beb6f4c 100644
--- a/py/objfun.c
+++ b/py/objfun.c
@@ -141,11 +141,11 @@ const mp_obj_type_t mp_type_fun_builtin_var = {
/* byte code functions */
qstr mp_obj_code_get_name(const byte *code_info) {
- mp_decode_uint(&code_info); // skip code_info_size entry
+ code_info = mp_decode_uint_skip(code_info); // skip code_info_size entry
#if MICROPY_PERSISTENT_CODE
return code_info[0] | (code_info[1] << 8);
#else
- return mp_decode_uint(&code_info);
+ return mp_decode_uint_value(code_info);
#endif
}
@@ -163,8 +163,8 @@ qstr mp_obj_fun_get_name(mp_const_obj_t fun_in) {
#endif
const byte *bc = fun->bytecode;
- mp_decode_uint(&bc); // skip n_state
- mp_decode_uint(&bc); // skip n_exc_stack
+ bc = mp_decode_uint_skip(bc); // skip n_state
+ bc = mp_decode_uint_skip(bc); // skip n_exc_stack
bc++; // skip scope_params
bc++; // skip n_pos_args
bc++; // skip n_kwonly_args
@@ -205,12 +205,9 @@ mp_code_state_t *mp_obj_fun_bc_prepare_codestate(mp_obj_t self_in, size_t n_args
MP_STACK_CHECK();
mp_obj_fun_bc_t *self = MP_OBJ_TO_PTR(self_in);
- // get start of bytecode
- const byte *ip = self->bytecode;
-
// bytecode prelude: state size and exception stack size
- size_t n_state = mp_decode_uint(&ip);
- size_t n_exc_stack = mp_decode_uint(&ip);
+ size_t n_state = mp_decode_uint_value(self->bytecode);
+ size_t n_exc_stack = mp_decode_uint_value(mp_decode_uint_skip(self->bytecode));
// allocate state for locals and stack
size_t state_size = n_state * sizeof(mp_obj_t) + n_exc_stack * sizeof(mp_exc_stack_t);
@@ -243,12 +240,9 @@ STATIC mp_obj_t fun_bc_call(mp_obj_t self_in, size_t n_args, size_t n_kw, const
mp_obj_fun_bc_t *self = MP_OBJ_TO_PTR(self_in);
DEBUG_printf("Func n_def_args: %d\n", self->n_def_args);
- // get start of bytecode
- const byte *ip = self->bytecode;
-
// bytecode prelude: state size and exception stack size
- size_t n_state = mp_decode_uint(&ip);
- size_t n_exc_stack = mp_decode_uint(&ip);
+ size_t n_state = mp_decode_uint_value(self->bytecode);
+ size_t n_exc_stack = mp_decode_uint_value(mp_decode_uint_skip(self->bytecode));
#if VM_DETECT_STACK_OVERFLOW
n_state += 1;
diff --git a/py/objgenerator.c b/py/objgenerator.c
index 2e57fdf4b6dac7abc68f110df59aaeab36d914cf..8cb0e60ccbb34a3befbe978ce150b48a392b43de 100644
--- a/py/objgenerator.c
+++ b/py/objgenerator.c
@@ -54,12 +54,9 @@ STATIC mp_obj_t gen_wrap_call(mp_obj_t self_in, size_t n_args, size_t n_kw, cons
mp_obj_fun_bc_t *self_fun = (mp_obj_fun_bc_t*)self->fun;
assert(self_fun->base.type == &mp_type_fun_bc);
- // get start of bytecode
- const byte *ip = self_fun->bytecode;
-
// bytecode prelude: get state size and exception stack size
- mp_uint_t n_state = mp_decode_uint(&ip);
- mp_uint_t n_exc_stack = mp_decode_uint(&ip);
+ size_t n_state = mp_decode_uint_value(self_fun->bytecode);
+ size_t n_exc_stack = mp_decode_uint_value(mp_decode_uint_skip(self_fun->bytecode));
// allocate the generator object, with room for local stack and exception stack
mp_obj_gen_instance_t *o = m_new_obj_var(mp_obj_gen_instance_t, byte,
diff --git a/py/vm.c b/py/vm.c
index ad3d9e29c8a68db6e3be1cdd0b70ddd060c98a5c..404c799123da8c76512dcc16335d554707ef97b4 100644
--- a/py/vm.c
+++ b/py/vm.c
@@ -1363,22 +1363,25 @@ unwind_loop:
// TODO need a better way of not adding traceback to constant objects (right now, just GeneratorExit_obj and MemoryError_obj)
if (nlr.ret_val != &mp_const_GeneratorExit_obj && nlr.ret_val != &mp_const_MemoryError_obj) {
const byte *ip = code_state->fun_bc->bytecode;
- mp_decode_uint(&ip); // skip n_state
- mp_decode_uint(&ip); // skip n_exc_stack
+ ip = mp_decode_uint_skip(ip); // skip n_state
+ ip = mp_decode_uint_skip(ip); // skip n_exc_stack
ip++; // skip scope_params
ip++; // skip n_pos_args
ip++; // skip n_kwonly_args
ip++; // skip n_def_pos_args
size_t bc = code_state->ip - ip;
- size_t code_info_size = mp_decode_uint(&ip);
+ size_t code_info_size = mp_decode_uint_value(ip);
+ ip = mp_decode_uint_skip(ip); // skip code_info_size
bc -= code_info_size;
#if MICROPY_PERSISTENT_CODE
qstr block_name = ip[0] | (ip[1] << 8);
qstr source_file = ip[2] | (ip[3] << 8);
ip += 4;
#else
- qstr block_name = mp_decode_uint(&ip);
- qstr source_file = mp_decode_uint(&ip);
+ qstr block_name = mp_decode_uint_value(ip);
+ ip = mp_decode_uint_skip(ip);
+ qstr source_file = mp_decode_uint_value(ip);
+ ip = mp_decode_uint_skip(ip);
#endif
size_t source_line = 1;
size_t c;