py: Add constant table to bytecode.

Contains just argument names at the moment but makes it easy to add
arbitrary constants.

12 files changed, 97 insertions, 96 deletions

diff --git a/py/bc.c b/py/bc.c
index da0ea78765..9f0e79c677 100644
--- a/py/bc.c
+++ b/py/bc.c
@@ -97,6 +97,9 @@ void mp_setup_code_state(mp_code_state *code_state, mp_obj_t self_in, mp_uint_t
     // ip comes in as an offset into bytecode, so turn it into a true pointer
     code_state->ip = self->bytecode + (mp_uint_t)code_state->ip;
 
+    // store pointer to constant table
+    code_state->const_table = self->const_table;
+
     #if MICROPY_STACKLESS
     code_state->prev = NULL;
     #endif
@@ -107,9 +110,6 @@ void mp_setup_code_state(mp_code_state *code_state, mp_obj_t self_in, mp_uint_t
     mp_uint_t n_kwonly_args = *code_state->ip++;
     mp_uint_t n_def_pos_args = *code_state->ip++;
 
-    // align ip
-    code_state->ip = MP_ALIGN(code_state->ip, sizeof(mp_uint_t));
-
     code_state->sp = &code_state->state[0] - 1;
     code_state->exc_sp = (mp_exc_stack_t*)(code_state->state + n_state) - 1;
 
@@ -168,7 +168,7 @@ void mp_setup_code_state(mp_code_state *code_state, mp_obj_t self_in, mp_uint_t
         }
 
         // get pointer to arg_names array
-        const mp_obj_t *arg_names = (const mp_obj_t*)code_state->ip;
+        const mp_obj_t *arg_names = (const mp_obj_t*)code_state->const_table;
 
         for (mp_uint_t i = 0; i < n_kw; i++) {
             mp_obj_t wanted_arg_name = kwargs[2 * i];
@@ -243,7 +243,6 @@ continue2:;
 
     // get the ip and skip argument names
     const byte *ip = code_state->ip;
-    ip += (n_pos_args + n_kwonly_args) * sizeof(mp_uint_t);
 
     // store pointer to code_info and jump over it
     {
diff --git a/py/bc.h b/py/bc.h
index 5824688d85..4c8401b9fa 100644
--- a/py/bc.h
+++ b/py/bc.h
@@ -38,24 +38,26 @@
 //  n_kwonly_args   : byte          number of keyword-only arguments this function takes
 //  n_def_pos_args  : byte          number of default positional arguments
 //
-//  <word alignment padding>
-//
-//  argname0        : obj (qstr)
-//  ...             : obj (qstr)
-//  argnameN        : obj (qstr)    N = num_pos_args + num_kwonly_args
-//
 //  code_info_size  : var uint |    code_info_size counts bytes in this chunk
 //  simple_name     : var qstr |
 //  source_file     : var qstr |
 //  <line number info>         |
-//  <word alignment padding>   |
+//  <word alignment padding>   |    only needed if bytecode contains pointers
 //
-//  num_cells       : byte          number of locals that are cells
-//  local_num0      : byte
-//  ...             : byte
-//  local_numN      : byte          N = num_cells
+//  local_num0      : byte     |
+//  ...             : byte     |
+//  local_numN      : byte     |    N = num_cells
+//  255             : byte     |    end of list sentinel
+//  <bytecode>                 |
 //
-//  <bytecode>
+//
+// constant table layout:
+//
+//  argname0        : obj (qstr)
+//  ...             : obj (qstr)
+//  argnameN        : obj (qstr)    N = num_pos_args + num_kwonly_args
+//  const0          : obj
+//  constN          : obj
 
 // Exception stack entry
 typedef struct _mp_exc_stack {
@@ -70,6 +72,7 @@ typedef struct _mp_exc_stack {
 typedef struct _mp_code_state {
     const byte *code_info;
     const byte *ip;
+    const mp_uint_t *const_table;
     mp_obj_t *sp;
     // bit 0 is saved currently_in_except_block value
     mp_exc_stack_t *exc_sp;
@@ -89,7 +92,7 @@ mp_uint_t mp_decode_uint(const byte **ptr);
 mp_vm_return_kind_t mp_execute_bytecode(mp_code_state *code_state, volatile mp_obj_t inject_exc);
 mp_code_state *mp_obj_fun_bc_prepare_codestate(mp_obj_t func, mp_uint_t n_args, mp_uint_t n_kw, const mp_obj_t *args);
 void mp_setup_code_state(mp_code_state *code_state, mp_obj_t self_in, mp_uint_t n_args, mp_uint_t n_kw, const mp_obj_t *args);
-void mp_bytecode_print(const void *descr, const byte *code, mp_uint_t len);
+void mp_bytecode_print(const void *descr, const byte *code, mp_uint_t len, const mp_uint_t *const_table);
 void mp_bytecode_print2(const byte *code, mp_uint_t len);
 const byte *mp_bytecode_print_str(const byte *ip);
 #define mp_bytecode_print_inst(code) mp_bytecode_print2(code, 1)
diff --git a/py/emitbc.c b/py/emitbc.c
index 6b45019015..abe782b0d3 100644
--- a/py/emitbc.c
+++ b/py/emitbc.c
@@ -56,6 +56,7 @@ struct _emit_t {
     mp_uint_t bytecode_offset;
     mp_uint_t bytecode_size;
     byte *code_base; // stores both byte code and code info
+    mp_uint_t *const_table;
     // Accessed as mp_uint_t, so must be aligned as such
     byte dummy_data[DUMMY_DATA_SIZE];
 };
@@ -123,13 +124,6 @@ STATIC void emit_write_code_info_qstr(emit_t *emit, qstr qst) {
     emit_write_uint(emit, emit_get_cur_to_write_code_info, qst);
 }
 
-STATIC void emit_write_code_info_prealigned_ptr(emit_t* emit, void *ptr) {
-    mp_uint_t *c = (mp_uint_t*)emit_get_cur_to_write_code_info(emit, sizeof(mp_uint_t));
-    // Verify thar c is already uint-aligned
-    assert(c == MP_ALIGN(c, sizeof(mp_uint_t)));
-    *c = (mp_uint_t)ptr;
-}
-
 #if MICROPY_ENABLE_SOURCE_LINE
 STATIC void emit_write_code_info_bytes_lines(emit_t *emit, mp_uint_t bytes_to_skip, mp_uint_t lines_to_skip) {
     assert(bytes_to_skip > 0 || lines_to_skip > 0);
@@ -301,37 +295,6 @@ void mp_emit_bc_start_pass(emit_t *emit, pass_kind_t pass, scope_t *scope) {
     emit_write_code_info_byte(emit, emit->scope->num_kwonly_args);
     emit_write_code_info_byte(emit, emit->scope->num_def_pos_args);
 
-    // Align code-info so that following pointers are aligned on a machine word.
-    emit_align_code_info_to_machine_word(emit);
-
-    // Write argument names (needed to resolve positional args passed as
-    // keywords).  We store them as full word-sized objects for efficient access
-    // in mp_setup_code_state this is the start of the prelude and is guaranteed
-    // to be aligned on a word boundary.
-    {
-        // For a given argument position (indexed by i) we need to find the
-        // corresponding id_info which is a parameter, as it has the correct
-        // qstr name to use as the argument name.  Note that it's not a simple
-        // 1-1 mapping (ie i!=j in general) because of possible closed-over
-        // variables.  In the case that the argument i has no corresponding
-        // parameter we use "*" as its name (since no argument can ever be named
-        // "*").  We could use a blank qstr but "*" is better for debugging.
-        // Note: there is some wasted RAM here for the case of storing a qstr
-        // for each closed-over variable, and maybe there is a better way to do
-        // it, but that would require changes to mp_setup_code_state.
-        for (int i = 0; i < scope->num_pos_args + scope->num_kwonly_args; i++) {
-            qstr qst = MP_QSTR__star_;
-            for (int j = 0; j < scope->id_info_len; ++j) {
-                id_info_t *id = &scope->id_info[j];
-                if ((id->flags & ID_FLAG_IS_PARAM) && id->local_num == i) {
-                    qst = id->qst;
-                    break;
-                }
-            }
-            emit_write_code_info_prealigned_ptr(emit, MP_OBJ_NEW_QSTR(qst));
-        }
-    }
-
     // Write size of the rest of the code info.  We don't know how big this
     // variable uint will be on the MP_PASS_CODE_SIZE pass so we reserve 2 bytes
     // for it and hope that is enough!  TODO assert this or something.
@@ -354,6 +317,35 @@ void mp_emit_bc_start_pass(emit_t *emit, pass_kind_t pass, scope_t *scope) {
         }
     }
     emit_write_bytecode_byte(emit, 255); // end of list sentinel
+
+    if (pass == MP_PASS_EMIT) {
+        // Write argument names (needed to resolve positional args passed as
+        // keywords).  We store them as full word-sized objects for efficient access
+        // in mp_setup_code_state this is the start of the prelude and is guaranteed
+        // to be aligned on a word boundary.
+
+        // For a given argument position (indexed by i) we need to find the
+        // corresponding id_info which is a parameter, as it has the correct
+        // qstr name to use as the argument name.  Note that it's not a simple
+        // 1-1 mapping (ie i!=j in general) because of possible closed-over
+        // variables.  In the case that the argument i has no corresponding
+        // parameter we use "*" as its name (since no argument can ever be named
+        // "*").  We could use a blank qstr but "*" is better for debugging.
+        // Note: there is some wasted RAM here for the case of storing a qstr
+        // for each closed-over variable, and maybe there is a better way to do
+        // it, but that would require changes to mp_setup_code_state.
+        for (int i = 0; i < scope->num_pos_args + scope->num_kwonly_args; i++) {
+            qstr qst = MP_QSTR__star_;
+            for (int j = 0; j < scope->id_info_len; ++j) {
+                id_info_t *id = &scope->id_info[j];
+                if ((id->flags & ID_FLAG_IS_PARAM) && id->local_num == i) {
+                    qst = id->qst;
+                    break;
+                }
+            }
+            emit->const_table[i] = (mp_uint_t)MP_OBJ_NEW_QSTR(qst);
+        }
+    }
 }
 
 void mp_emit_bc_end_pass(emit_t *emit) {
@@ -377,9 +369,12 @@ void mp_emit_bc_end_pass(emit_t *emit) {
         emit->bytecode_size = emit->bytecode_offset;
         emit->code_base = m_new0(byte, emit->code_info_size + emit->bytecode_size);
 
+        emit->const_table = m_new0(mp_uint_t, emit->scope->num_pos_args + emit->scope->num_kwonly_args);
+
     } else if (emit->pass == MP_PASS_EMIT) {
         mp_emit_glue_assign_bytecode(emit->scope->raw_code, emit->code_base,
-            emit->code_info_size + emit->bytecode_size, emit->scope->scope_flags);
+            emit->code_info_size + emit->bytecode_size,
+            emit->const_table, emit->scope->scope_flags);
     }
 }
 
diff --git a/py/emitglue.c b/py/emitglue.c
index 83fe420b7b..feed5d99a2 100644
--- a/py/emitglue.c
+++ b/py/emitglue.c
@@ -51,9 +51,11 @@ struct _mp_raw_code_t {
     union {
         struct {
             const byte *code;
+            const mp_uint_t *const_table;
         } u_byte;
         struct {
             void *fun_data;
+            const mp_uint_t *const_table;
             mp_uint_t type_sig; // for viper, compressed as 2-bit types; ret is MSB, then arg0, arg1, etc
         } u_native;
     } data;
@@ -65,28 +67,30 @@ mp_raw_code_t *mp_emit_glue_new_raw_code(void) {
     return rc;
 }
 
-void mp_emit_glue_assign_bytecode(mp_raw_code_t *rc, byte *code, mp_uint_t len, mp_uint_t scope_flags) {
+void mp_emit_glue_assign_bytecode(mp_raw_code_t *rc, const byte *code, mp_uint_t len, const mp_uint_t *const_table, mp_uint_t scope_flags) {
     rc->kind = MP_CODE_BYTECODE;
     rc->scope_flags = scope_flags;
     rc->data.u_byte.code = code;
+    rc->data.u_byte.const_table = const_table;
 
 #ifdef DEBUG_PRINT
     DEBUG_printf("assign byte code: code=%p len=" UINT_FMT " flags=%x\n", code, len, (uint)scope_flags);
 #endif
 #if MICROPY_DEBUG_PRINTERS
     if (mp_verbose_flag >= 2) {
-        mp_bytecode_print(rc, code, len);
+        mp_bytecode_print(rc, code, len, const_table);
     }
 #endif
 }
 
 #if MICROPY_EMIT_NATIVE || MICROPY_EMIT_INLINE_THUMB
-void mp_emit_glue_assign_native(mp_raw_code_t *rc, mp_raw_code_kind_t kind, void *fun_data, mp_uint_t fun_len, mp_uint_t n_pos_args, mp_uint_t scope_flags, mp_uint_t type_sig) {
+void mp_emit_glue_assign_native(mp_raw_code_t *rc, mp_raw_code_kind_t kind, void *fun_data, mp_uint_t fun_len, const mp_uint_t *const_table, mp_uint_t n_pos_args, mp_uint_t scope_flags, mp_uint_t type_sig) {
     assert(kind == MP_CODE_NATIVE_PY || kind == MP_CODE_NATIVE_VIPER || kind == MP_CODE_NATIVE_ASM);
     rc->kind = kind;
     rc->scope_flags = scope_flags;
     rc->n_pos_args = n_pos_args;
     rc->data.u_native.fun_data = fun_data;
+    rc->data.u_native.const_table = const_table;
     rc->data.u_native.type_sig = type_sig;
 
 #ifdef DEBUG_PRINT
@@ -125,11 +129,11 @@ mp_obj_t mp_make_function_from_raw_code(mp_raw_code_t *rc, mp_obj_t def_args, mp
     switch (rc->kind) {
         case MP_CODE_BYTECODE:
         no_other_choice:
-            fun = mp_obj_new_fun_bc(def_args, def_kw_args, rc->data.u_byte.code);
+            fun = mp_obj_new_fun_bc(def_args, def_kw_args, rc->data.u_byte.code, rc->data.u_byte.const_table);
             break;
         #if MICROPY_EMIT_NATIVE
         case MP_CODE_NATIVE_PY:
-            fun = mp_obj_new_fun_native(def_args, def_kw_args, rc->data.u_native.fun_data);
+            fun = mp_obj_new_fun_native(def_args, def_kw_args, rc->data.u_native.fun_data, rc->data.u_native.const_table);
             break;
         case MP_CODE_NATIVE_VIPER:
             fun = mp_obj_new_fun_viper(rc->n_pos_args, rc->data.u_native.fun_data, rc->data.u_native.type_sig);
diff --git a/py/emitglue.h b/py/emitglue.h
index 56029b3a9b..9bb2ba2d74 100644
--- a/py/emitglue.h
+++ b/py/emitglue.h
@@ -43,8 +43,8 @@ typedef struct _mp_raw_code_t mp_raw_code_t;
 
 mp_raw_code_t *mp_emit_glue_new_raw_code(void);
 
-void mp_emit_glue_assign_bytecode(mp_raw_code_t *rc, byte *code, mp_uint_t len, mp_uint_t scope_flags);
-void mp_emit_glue_assign_native(mp_raw_code_t *rc, mp_raw_code_kind_t kind, void *fun_data, mp_uint_t fun_len, mp_uint_t n_pos_args, mp_uint_t scope_flags, mp_uint_t type_sig);
+void mp_emit_glue_assign_bytecode(mp_raw_code_t *rc, const byte *code, mp_uint_t len, const mp_uint_t *const_table, mp_uint_t scope_flags);
+void mp_emit_glue_assign_native(mp_raw_code_t *rc, mp_raw_code_kind_t kind, void *fun_data, mp_uint_t fun_len, const mp_uint_t *const_table, mp_uint_t n_pos_args, mp_uint_t scope_flags, mp_uint_t type_sig);
 
 mp_obj_t mp_make_function_from_raw_code(mp_raw_code_t *rc, mp_obj_t def_args, mp_obj_t def_kw_args);
 mp_obj_t mp_make_closure_from_raw_code(mp_raw_code_t *rc, mp_uint_t n_closed_over, const mp_obj_t *args);
diff --git a/py/emitinlinethumb.c b/py/emitinlinethumb.c
index 14cbf57ec2..949ef7a133 100644
--- a/py/emitinlinethumb.c
+++ b/py/emitinlinethumb.c
@@ -90,7 +90,7 @@ STATIC void emit_inline_thumb_end_pass(emit_inline_asm_t *emit) {
 
     if (emit->pass == MP_PASS_EMIT) {
         void *f = asm_thumb_get_code(emit->as);
-        mp_emit_glue_assign_native(emit->scope->raw_code, MP_CODE_NATIVE_ASM, f, asm_thumb_get_code_size(emit->as), emit->scope->num_pos_args, 0, 0);
+        mp_emit_glue_assign_native(emit->scope->raw_code, MP_CODE_NATIVE_ASM, f, asm_thumb_get_code_size(emit->as), NULL, emit->scope->num_pos_args, 0, 0);
     }
 }
 
diff --git a/py/emitnative.c b/py/emitnative.c
index 99eac79253..d8f1640c0f 100644
--- a/py/emitnative.c
+++ b/py/emitnative.c
@@ -567,6 +567,7 @@ struct _emit_t {
     vtype_kind_t saved_stack_vtype;
 
     int prelude_offset;
+    int const_table_offset;
     int n_state;
     int stack_start;
     int stack_size;
@@ -828,7 +829,24 @@ STATIC void emit_native_end_pass(emit_t *emit) {
         ASM_DATA(emit->as, 1, emit->scope->num_pos_args);
         ASM_DATA(emit->as, 1, emit->scope->num_kwonly_args);
         ASM_DATA(emit->as, 1, emit->scope->num_def_pos_args);
+
+        // write code info (just contains block name and source file)
+        ASM_DATA(emit->as, 1, 5);
+        ASM_DATA(emit->as, 2, emit->scope->simple_name);
+        ASM_DATA(emit->as, 2, emit->scope->source_file);
+
+        // bytecode prelude: initialise closed over variables
+        for (int i = 0; i < emit->scope->id_info_len; i++) {
+            id_info_t *id = &emit->scope->id_info[i];
+            if (id->kind == ID_INFO_KIND_CELL) {
+                assert(id->local_num < 255);
+                ASM_DATA(emit->as, 1, id->local_num); // write the local which should be converted to a cell
+            }
+        }
+        ASM_DATA(emit->as, 1, 255); // end of list sentinel
+
         ASM_ALIGN(emit->as, ASM_WORD_SIZE);
+        emit->const_table_offset = ASM_GET_CODE_POS(emit->as);
 
         // write argument names as qstr objects
         // see comment in corresponding part of emitbc.c about the logic here
@@ -844,18 +862,6 @@ STATIC void emit_native_end_pass(emit_t *emit) {
             ASM_DATA(emit->as, ASM_WORD_SIZE, (mp_uint_t)MP_OBJ_NEW_QSTR(qst));
         }
 
-        // write dummy code info (for mp_setup_code_state to parse)
-        ASM_DATA(emit->as, 1, 1);
-
-        // bytecode prelude: initialise closed over variables
-        for (int i = 0; i < emit->scope->id_info_len; i++) {
-            id_info_t *id = &emit->scope->id_info[i];
-            if (id->kind == ID_INFO_KIND_CELL) {
-                assert(id->local_num < 255);
-                ASM_DATA(emit->as, 1, id->local_num); // write the local which should be converted to a cell
-            }
-        }
-        ASM_DATA(emit->as, 1, 255); // end of list sentinel
     }
 
     ASM_END_PASS(emit->as);
@@ -878,7 +884,8 @@ STATIC void emit_native_end_pass(emit_t *emit) {
 
         mp_emit_glue_assign_native(emit->scope->raw_code,
             emit->do_viper_types ? MP_CODE_NATIVE_VIPER : MP_CODE_NATIVE_PY,
-            f, f_len, emit->scope->num_pos_args, emit->scope->scope_flags, type_sig);
+            f, f_len, (mp_uint_t*)((byte*)f + emit->const_table_offset),
+            emit->scope->num_pos_args, emit->scope->scope_flags, type_sig);
     }
 }
 
diff --git a/py/obj.h b/py/obj.h
index a627a4143b..82da555e37 100644
--- a/py/obj.h
+++ b/py/obj.h
@@ -537,8 +537,8 @@ mp_obj_t mp_obj_new_exception_arg1(const mp_obj_type_t *exc_type, mp_obj_t arg);
 mp_obj_t mp_obj_new_exception_args(const mp_obj_type_t *exc_type, mp_uint_t n_args, const mp_obj_t *args);
 mp_obj_t mp_obj_new_exception_msg(const mp_obj_type_t *exc_type, const char *msg);
 mp_obj_t mp_obj_new_exception_msg_varg(const mp_obj_type_t *exc_type, const char *fmt, ...); // counts args by number of % symbols in fmt, excluding %%; can only handle void* sizes (ie no float/double!)
-mp_obj_t mp_obj_new_fun_bc(mp_obj_t def_args, mp_obj_t def_kw_args, const byte *code);
-mp_obj_t mp_obj_new_fun_native(mp_obj_t def_args_in, mp_obj_t def_kw_args, const void *fun_data);
+mp_obj_t mp_obj_new_fun_bc(mp_obj_t def_args, mp_obj_t def_kw_args, const byte *code, const mp_uint_t *const_table);
+mp_obj_t mp_obj_new_fun_native(mp_obj_t def_args_in, mp_obj_t def_kw_args, const void *fun_data, const mp_uint_t *const_table);
 mp_obj_t mp_obj_new_fun_viper(mp_uint_t n_args, void *fun_data, mp_uint_t type_sig);
 mp_obj_t mp_obj_new_fun_asm(mp_uint_t n_args, void *fun_data);
 mp_obj_t mp_obj_new_gen_wrap(mp_obj_t fun);
diff --git a/py/objfun.c b/py/objfun.c
index a54e50d2cd..f55d44ca29 100644
--- a/py/objfun.c
+++ b/py/objfun.c
@@ -126,11 +126,9 @@ qstr mp_obj_fun_get_name(mp_const_obj_t fun_in) {
     mp_decode_uint(&bc); // skip n_state
     mp_decode_uint(&bc); // skip n_exc_stack
     bc++; // skip scope_params
-    mp_uint_t n_pos_args = *bc++;
-    mp_uint_t n_kwonly_args = *bc++;
+    bc++; // skip n_pos_args
+    bc++; // skip n_kwonly_args
     bc++; // skip n_def_pos_args
-    bc = MP_ALIGN(bc, sizeof(mp_uint_t)); // align
-    bc += (n_pos_args + n_kwonly_args) * sizeof(mp_uint_t); // skip arg names
     return mp_obj_code_get_name(bc);
 }
 
@@ -320,7 +318,7 @@ const mp_obj_type_t mp_type_fun_bc = {
 #endif
 };
 
-mp_obj_t mp_obj_new_fun_bc(mp_obj_t def_args_in, mp_obj_t def_kw_args, const byte *code) {
+mp_obj_t mp_obj_new_fun_bc(mp_obj_t def_args_in, mp_obj_t def_kw_args, const byte *code, const mp_uint_t *const_table) {
     mp_uint_t n_def_args = 0;
     mp_uint_t n_extra_args = 0;
     mp_obj_tuple_t *def_args = def_args_in;
@@ -336,6 +334,7 @@ mp_obj_t mp_obj_new_fun_bc(mp_obj_t def_args_in, mp_obj_t def_kw_args, const byt
     o->base.type = &mp_type_fun_bc;
     o->globals = mp_globals_get();
     o->bytecode = code;
+    o->const_table = const_table;
     if (def_args != MP_OBJ_NULL) {
         memcpy(o->extra_args, def_args->items, n_def_args * sizeof(mp_obj_t));
     }
@@ -364,8 +363,8 @@ STATIC const mp_obj_type_t mp_type_fun_native = {
     .unary_op = mp_generic_unary_op,
 };
 
-mp_obj_t mp_obj_new_fun_native(mp_obj_t def_args_in, mp_obj_t def_kw_args, const void *fun_data) {
-    mp_obj_fun_bc_t *o = mp_obj_new_fun_bc(def_args_in, def_kw_args, (const byte*)fun_data);
+mp_obj_t mp_obj_new_fun_native(mp_obj_t def_args_in, mp_obj_t def_kw_args, const void *fun_data, const mp_uint_t *const_table) {
+    mp_obj_fun_bc_t *o = mp_obj_new_fun_bc(def_args_in, def_kw_args, (const byte*)fun_data, const_table);
     o->base.type = &mp_type_fun_native;
     return o;
 }
diff --git a/py/objfun.h b/py/objfun.h
index cdc495e5be..d02fada9b1 100644
--- a/py/objfun.h
+++ b/py/objfun.h
@@ -32,6 +32,7 @@ typedef struct _mp_obj_fun_bc_t {
     mp_obj_base_t base;
     mp_obj_dict_t *globals;         // the context within which this function was defined
     const byte *bytecode;           // bytecode for the function
+    const mp_uint_t *const_table;   // constant table
     // the following extra_args array is allocated space to take (in order):
     //  - values of positional default args (if any)
     //  - a single slot for default kw args dict (if it has them)
diff --git a/py/objgenerator.c b/py/objgenerator.c
index f7b637e471..59ca6b85fc 100644
--- a/py/objgenerator.c
+++ b/py/objgenerator.c
@@ -68,7 +68,6 @@ STATIC mp_obj_t gen_wrap_call(mp_obj_t self_in, mp_uint_t n_args, mp_uint_t n_kw
 
     o->globals = self_fun->globals;
     o->code_state.n_state = n_state;
-    o->code_state.code_info = 0; // offset to code-info
     o->code_state.ip = (byte*)(ip - self_fun->bytecode); // offset to prelude
     mp_setup_code_state(&o->code_state, self_fun, n_args, n_kw, args);
     return o;
diff --git a/py/showbc.c b/py/showbc.c
index 538eddc40f..62c6168b78 100644
--- a/py/showbc.c
+++ b/py/showbc.c
@@ -54,7 +54,7 @@
 
 const byte *mp_showbc_code_start;
 
-void mp_bytecode_print(const void *descr, const byte *ip, mp_uint_t len) {
+void mp_bytecode_print(const void *descr, const byte *ip, mp_uint_t len, const mp_uint_t *const_table) {
     mp_showbc_code_start = ip;
 
     // get bytecode parameters
@@ -65,12 +65,6 @@ void mp_bytecode_print(const void *descr, const byte *ip, mp_uint_t len) {
     mp_uint_t n_kwonly_args = *ip++;
     /*mp_uint_t n_def_pos_args =*/ ip++;
 
-    ip = MP_ALIGN(ip, sizeof(mp_uint_t));
-
-    // get and skip arg names
-    const mp_obj_t *arg_names = (const mp_obj_t*)ip;
-    ip += (n_pos_args + n_kwonly_args) * sizeof(mp_uint_t);
-
     const byte *code_info = ip;
     mp_uint_t code_info_size = mp_decode_uint(&code_info);
     ip += code_info_size;
@@ -93,7 +87,7 @@ void mp_bytecode_print(const void *descr, const byte *ip, mp_uint_t len) {
     // bytecode prelude: arg names (as qstr objects)
     printf("arg names:");
     for (mp_uint_t i = 0; i < n_pos_args + n_kwonly_args; i++) {
-        printf(" %s", qstr_str(MP_OBJ_QSTR_VALUE(arg_names[i])));
+        printf(" %s", qstr_str(MP_OBJ_QSTR_VALUE(const_table[i])));
     }
     printf("\n");