Merge remote-tracking branch 'micropython/master'

Conflicts:
	README.md - Kept Adafruit README.md intact.
	py/emitglue.c - Added xtensa architecture as an OR of the define.
	zephyr/README.md - Fixed spelling mistake.

39 files changed, 189 insertions, 224 deletions

diff --git a/py/argcheck.c b/py/argcheck.c
index a6c769ee8..8cef10b16 100644
--- a/py/argcheck.c
+++ b/py/argcheck.c
@@ -37,8 +37,7 @@ void mp_arg_check_num(size_t n_args, size_t n_kw, size_t n_args_min, size_t n_ar
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
             mp_arg_error_terse_mismatch();
         } else {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "function does not take keyword arguments"));
+            mp_raise_msg(&mp_type_TypeError, "function does not take keyword arguments");
         }
     }
 
@@ -116,8 +115,7 @@ void mp_arg_parse_all(size_t n_pos, const mp_obj_t *pos, mp_map_t *kws, size_t n
             mp_arg_error_terse_mismatch();
         } else {
             // TODO better error message
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "extra positional arguments given"));
+            mp_raise_msg(&mp_type_TypeError, "extra positional arguments given");
         }
     }
     if (kws_found < kws->used) {
@@ -125,8 +123,7 @@ void mp_arg_parse_all(size_t n_pos, const mp_obj_t *pos, mp_map_t *kws, size_t n
             mp_arg_error_terse_mismatch();
         } else {
             // TODO better error message
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "extra keyword arguments given"));
+            mp_raise_msg(&mp_type_TypeError, "extra keyword arguments given");
         }
     }
 }
@@ -139,7 +136,7 @@ void mp_arg_parse_all_kw_array(size_t n_pos, size_t n_kw, const mp_obj_t *args,
 
 #if MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE || _MSC_VER
 NORETURN void mp_arg_error_terse_mismatch(void) {
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "argument num/types mismatch"));
+    mp_raise_msg(&mp_type_TypeError, "argument num/types mismatch");
 }
 #endif
 
diff --git a/py/bc.c b/py/bc.c
index e5abea244..07de08fc3 100644
--- a/py/bc.c
+++ b/py/bc.c
@@ -185,7 +185,7 @@ void mp_setup_code_state(mp_code_state_t *code_state, mp_obj_fun_bc_t *self, siz
             }
             // Didn't find name match with positional args
             if ((scope_flags & MP_SCOPE_FLAG_VARKEYWORDS) == 0) {
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "function does not take keyword arguments"));
+                mp_raise_msg(&mp_type_TypeError, "function does not take keyword arguments");
             }
             mp_obj_dict_store(dict, kwargs[2 * i], kwargs[2 * i + 1]);
 continue2:;
@@ -234,8 +234,7 @@ continue2:;
     } else {
         // no keyword arguments given
         if (n_kwonly_args != 0) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "function missing keyword-only argument"));
+            mp_raise_msg(&mp_type_TypeError, "function missing keyword-only argument");
         }
         if ((scope_flags & MP_SCOPE_FLAG_VARKEYWORDS) != 0) {
             *var_pos_kw_args = mp_obj_new_dict(0);
diff --git a/py/builtinevex.c b/py/builtinevex.c
index 74c43b176..636f86930 100644
--- a/py/builtinevex.c
+++ b/py/builtinevex.c
@@ -95,7 +95,7 @@ STATIC mp_obj_t mp_builtin_compile(size_t n_args, const mp_obj_t *args) {
         case MP_QSTR_exec: parse_input_kind = MP_PARSE_FILE_INPUT; break;
         case MP_QSTR_eval: parse_input_kind = MP_PARSE_EVAL_INPUT; break;
         default:
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "bad compile mode"));
+            mp_raise_msg(&mp_type_ValueError, "bad compile mode");
     }
 
     mp_obj_code_t *code = m_new_obj(mp_obj_code_t);
diff --git a/py/builtinimport.c b/py/builtinimport.c
index e4199f25d..e72eaf472 100644
--- a/py/builtinimport.c
+++ b/py/builtinimport.c
@@ -138,7 +138,7 @@ STATIC void do_load_from_lexer(mp_obj_t module_obj, mp_lexer_t *lex, const char
     if (lex == NULL) {
         // we verified the file exists using stat, but lexer could still fail
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_ImportError, "module not found"));
+            mp_raise_msg(&mp_type_ImportError, "module not found");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ImportError,
                 "no module named '%s'", fname));
@@ -340,7 +340,7 @@ mp_obj_t mp_builtin___import__(size_t n_args, const mp_obj_t *args) {
             DEBUG_printf("Warning: no dots in current module name and level>0\n");
             p = this_name + this_name_l;
         } else if (level != -1) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_ImportError, "Invalid relative import"));
+            mp_raise_msg(&mp_type_ImportError, "invalid relative import");
         }
 
         uint new_mod_l = (mod_len == 0 ? (size_t)(p - this_name) : (size_t)(p - this_name) + 1 + mod_len);
@@ -355,7 +355,7 @@ mp_obj_t mp_builtin___import__(size_t n_args, const mp_obj_t *args) {
         DEBUG_printf("Resolved base name for relative import: '%s'\n", qstr_str(new_mod_q));
         if (new_mod_q == MP_QSTR_) {
             // CPython raises SystemError
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_ImportError, "cannot perform relative import"));
+            mp_raise_msg(&mp_type_ImportError, "cannot perform relative import");
         }
         module_name = MP_OBJ_NEW_QSTR(new_mod_q);
         mod_str = new_mod;
@@ -425,7 +425,7 @@ mp_obj_t mp_builtin___import__(size_t n_args, const mp_obj_t *args) {
                 #endif
                     // couldn't find the file, so fail
                     if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-                        nlr_raise(mp_obj_new_exception_msg(&mp_type_ImportError, "module not found"));
+                        mp_raise_msg(&mp_type_ImportError, "module not found");
                     } else {
                         nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ImportError,
                             "no module named '%q'", mod_name));
diff --git a/py/compile.c b/py/compile.c
index 0ea8a3c15..f84d5e214 100644
--- a/py/compile.c
+++ b/py/compile.c
@@ -2723,15 +2723,8 @@ STATIC void compile_node(compiler_t *comp, mp_parse_node_t pn) {
         mp_parse_node_struct_t *pns = (mp_parse_node_struct_t*)pn;
         EMIT_ARG(set_source_line, pns->source_line);
         compile_function_t f = compile_function[MP_PARSE_NODE_STRUCT_KIND(pns)];
-        if (f == NULL) {
-#if MICROPY_DEBUG_PRINTERS
-            printf("node %u cannot be compiled\n", (uint)MP_PARSE_NODE_STRUCT_KIND(pns));
-            mp_parse_node_print(pn, 0);
-#endif
-            compile_syntax_error(comp, pn, "internal compiler error");
-        } else {
-            f(comp, pns);
-        }
+        assert(f != NULL);
+        f(comp, pns);
     }
 }
 
@@ -2836,12 +2829,10 @@ STATIC void compile_scope_func_annotations(compiler_t *comp, mp_parse_node_t pn)
             // no annotation
             return;
         }
-    } else if (MP_PARSE_NODE_STRUCT_KIND(pns) == PN_typedargslist_dbl_star) {
+    } else {
+        assert(MP_PARSE_NODE_STRUCT_KIND(pns) == PN_typedargslist_dbl_star);
         // double star with possible annotation
         // fallthrough
-    } else {
-        // no annotation
-        return;
     }
 
     mp_parse_node_t pn_annotation = pns->nodes[1];
diff --git a/py/emitglue.c b/py/emitglue.c
index 2bfc4ad82..c81387fd4 100644
--- a/py/emitglue.c
+++ b/py/emitglue.c
@@ -425,7 +425,7 @@ mp_raw_code_t *mp_raw_code_load_file(const char *filename) {
     return rc;
 }
 
-#elif defined(__thumb2__) || defined(__thumb__)
+#elif defined(__thumb2__) || defined(__thumb__) || defined(__xtensa__)
 // fatfs file reader (assume thumb2 arch uses fatfs...)
 
 #include "lib/fatfs/ff.h"
diff --git a/py/lexer.c b/py/lexer.c
index b2c9c5ff7..4a7c8f580 100644
--- a/py/lexer.c
+++ b/py/lexer.c
@@ -343,7 +343,6 @@ STATIC void mp_lexer_next_token_into(mp_lexer_t *lex, bool first_token) {
         lex->tok_kind = MP_TOKEN_NEWLINE;
 
         mp_uint_t num_spaces = lex->column - 1;
-        lex->emit_dent = 0;
         if (num_spaces == indent_top(lex)) {
         } else if (num_spaces > indent_top(lex)) {
             indent_push(lex, num_spaces);
@@ -359,16 +358,7 @@ STATIC void mp_lexer_next_token_into(mp_lexer_t *lex, bool first_token) {
         }
 
     } else if (is_end(lex)) {
-        if (indent_top(lex) > 0) {
-            lex->tok_kind = MP_TOKEN_NEWLINE;
-            lex->emit_dent = 0;
-            while (indent_top(lex) > 0) {
-                indent_pop(lex);
-                lex->emit_dent -= 1;
-            }
-        } else {
-            lex->tok_kind = MP_TOKEN_END;
-        }
+        lex->tok_kind = MP_TOKEN_END;
 
     } else if (is_char_or(lex, '\'', '\"')
                || (is_char_or3(lex, 'r', 'u', 'b') && is_char_following_or(lex, '\'', '\"'))
diff --git a/py/misc.h b/py/misc.h
index 3ed227a35..e60665e59 100644
--- a/py/misc.h
+++ b/py/misc.h
@@ -151,8 +151,7 @@ void vstr_init_fixed_buf(vstr_t *vstr, size_t alloc, char *buf);
 struct _mp_print_t;
 void vstr_init_print(vstr_t *vstr, size_t alloc, struct _mp_print_t *print);
 void vstr_clear(vstr_t *vstr);
-vstr_t *vstr_new(void);
-vstr_t *vstr_new_size(size_t alloc);
+vstr_t *vstr_new(size_t alloc);
 void vstr_free(vstr_t *vstr);
 static inline void vstr_reset(vstr_t *vstr) { vstr->len = 0; }
 static inline char *vstr_str(vstr_t *vstr) { return vstr->buf; }
diff --git a/py/modbuiltins.c b/py/modbuiltins.c
index 29f84d6c2..57e52efa5 100644
--- a/py/modbuiltins.c
+++ b/py/modbuiltins.c
@@ -178,7 +178,7 @@ STATIC mp_obj_t mp_builtin_chr(mp_obj_t o_in) {
         str[3] = (c & 0x3F) | 0x80;
         len = 4;
     } else {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "chr() arg not in range(0x110000)"));
+        mp_raise_msg(&mp_type_ValueError, "chr() arg not in range(0x110000)");
     }
     return mp_obj_new_str(str, len, true);
     #else
@@ -187,7 +187,7 @@ STATIC mp_obj_t mp_builtin_chr(mp_obj_t o_in) {
         char str[1] = {ord};
         return mp_obj_new_str(str, 1, true);
     } else {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "chr() arg not in range(256)"));
+        mp_raise_msg(&mp_type_ValueError, "chr() arg not in range(256)");
     }
     #endif
 }
@@ -286,7 +286,7 @@ STATIC mp_obj_t mp_builtin_min_max(size_t n_args, const mp_obj_t *args, mp_map_t
             if (default_elem != NULL) {
                 best_obj = default_elem->value;
             } else {
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "arg is an empty sequence"));
+                mp_raise_msg(&mp_type_ValueError, "arg is an empty sequence");
             }
         }
         return best_obj;
@@ -507,8 +507,7 @@ MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_builtin_sum_obj, 1, 2, mp_builtin_sum);
 
 STATIC mp_obj_t mp_builtin_sorted(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs) {
     if (n_args > 1) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                                          "must use keyword argument for key function"));
+        mp_raise_msg(&mp_type_TypeError, "must use keyword argument for key function");
     }
     mp_obj_t self = mp_type_list.make_new(&mp_type_list, 1, 0, args);
     mp_obj_list_sort(1, &self, kwargs);
diff --git a/py/modmicropython.c b/py/modmicropython.c
index f7d74db2e..675d169cc 100644
--- a/py/modmicropython.c
+++ b/py/modmicropython.c
@@ -34,6 +34,16 @@
 // Various builtins specific to MicroPython runtime,
 // living in micropython module
 
+STATIC mp_obj_t mp_micropython_opt_level(size_t n_args, const mp_obj_t *args) {
+    if (n_args == 0) {
+        return MP_OBJ_NEW_SMALL_INT(MP_STATE_VM(mp_optimise_value));
+    } else {
+        MP_STATE_VM(mp_optimise_value) = mp_obj_get_int(args[0]);
+        return mp_const_none;
+    }
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_micropython_opt_level_obj, 0, 1, mp_micropython_opt_level);
+
 #if MICROPY_PY_MICROPYTHON_MEM_INFO
 
 #if MICROPY_MEM_STATS
@@ -121,6 +131,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_1(mp_alloc_emergency_exception_buf_obj, mp_alloc_
 STATIC const mp_rom_map_elem_t mp_module_micropython_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_micropython) },
     { MP_ROM_QSTR(MP_QSTR_const), MP_ROM_PTR(&mp_identity_obj) },
+    { MP_ROM_QSTR(MP_QSTR_opt_level), MP_ROM_PTR(&mp_micropython_opt_level_obj) },
 #if MICROPY_PY_MICROPYTHON_MEM_INFO
 #if MICROPY_MEM_STATS
     { MP_ROM_QSTR(MP_QSTR_mem_total), MP_ROM_PTR(&mp_micropython_mem_total_obj) },
diff --git a/py/modthread.c b/py/modthread.c
index c358cdf9e..6f55281ad 100644
--- a/py/modthread.c
+++ b/py/modthread.c
@@ -239,7 +239,7 @@ STATIC mp_obj_t mod_thread_start_new_thread(size_t n_args, const mp_obj_t *args)
     } else {
         // positional and keyword arguments
         if (mp_obj_get_type(args[2]) != &mp_type_dict) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "expecting a dict for keyword args"));
+            mp_raise_msg(&mp_type_TypeError, "expecting a dict for keyword args");
         }
         mp_map_t *map = &((mp_obj_dict_t*)MP_OBJ_TO_PTR(args[2]))->map;
         th_args = m_new_obj_var(thread_entry_args_t, mp_obj_t, pos_args_len + 2 * map->used);
diff --git a/py/mpconfig.h b/py/mpconfig.h
index e33a41f7a..dcdaffe0f 100644
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -860,6 +860,12 @@ typedef double mp_float_t;
 #define MICROPY_PY_UERRNO (0)
 #endif
 
+// Whether to provide "utime" module functions implementation
+// in terms of mp_hal_* functions.
+#ifndef MICROPY_PY_UTIME_MP_HAL
+#define MICROPY_PY_UTIME_MP_HAL (0)
+#endif
+
 // Whether to provide "_thread" module
 #ifndef MICROPY_PY_THREAD
 #define MICROPY_PY_THREAD (0)
diff --git a/py/mphal.h b/py/mphal.h
index 54a45b024..8d5654f9e 100644
--- a/py/mphal.h
+++ b/py/mphal.h
@@ -66,6 +66,10 @@ mp_uint_t mp_hal_ticks_ms(void);
 mp_uint_t mp_hal_ticks_us(void);
 #endif
 
+#ifndef mp_hal_ticks_cpu
+mp_uint_t mp_hal_ticks_cpu(void);
+#endif
+
 // If port HAL didn't define its own pin API, use generic
 // "virtual pin" API from the core.
 #ifndef mp_hal_pin_obj_t
diff --git a/py/mpprint.c b/py/mpprint.c
index 97ea33ad2..9ad0f3f9a 100644
--- a/py/mpprint.c
+++ b/py/mpprint.c
@@ -252,8 +252,8 @@ int mp_print_mp_int(const mp_print_t *print, mp_obj_t x, int base, int base_char
     // enough, a dynamic one will be allocated.
     char stack_buf[sizeof(mp_int_t) * 4];
     char *buf = stack_buf;
-    mp_uint_t buf_size = sizeof(stack_buf);
-    mp_uint_t fmt_size = 0;
+    size_t buf_size = sizeof(stack_buf);
+    size_t fmt_size = 0;
     char *str;
 
     if (prec > 1) {
diff --git a/py/mpz.c b/py/mpz.c
index bb7647956..cceb079cd 100644
--- a/py/mpz.c
+++ b/py/mpz.c
@@ -645,18 +645,6 @@ STATIC void mpn_div(mpz_dig_t *num_dig, mp_uint_t *num_len, const mpz_dig_t *den
 
 #define MIN_ALLOC (2)
 
-STATIC const uint8_t log_base2_floor[] = {
-    0,
-    0, 1, 1, 2,
-    2, 2, 2, 3,
-    3, 3, 3, 3,
-    3, 3, 3, 4,
-    4, 4, 4, 4,
-    4, 4, 4, 4,
-    4, 4, 4, 4,
-    4, 4, 4, 5
-};
-
 void mpz_init_zero(mpz_t *z) {
     z->neg = 0;
     z->fixed_dig = 0;
@@ -734,11 +722,9 @@ STATIC void mpz_need_dig(mpz_t *z, mp_uint_t need) {
     }
 
     if (z->dig == NULL || z->alloc < need) {
-        if (z->fixed_dig) {
-            // cannot reallocate fixed buffers
-            assert(0);
-            return;
-        }
+        // if z has fixed digit buffer there's not much we can do as the caller will
+        // be expecting a buffer with at least "need" bytes (but it shouldn't happen)
+        assert(!z->fixed_dig);
         z->dig = m_renew(mpz_dig_t, z->dig, z->alloc, need);
         z->alloc = need;
     }
@@ -1497,13 +1483,10 @@ mpz_t *mpz_lcm(const mpz_t *z1, const mpz_t *z2) {
        quo * rhs + rem = lhs
        0 <= rem < rhs
    can have lhs, rhs the same
+   assumes rhs != 0 (undefined behaviour if it is)
 */
 void mpz_divmod_inpl(mpz_t *dest_quo, mpz_t *dest_rem, const mpz_t *lhs, const mpz_t *rhs) {
-    if (rhs->len == 0) {
-        mpz_set_from_int(dest_quo, 0);
-        mpz_set_from_int(dest_rem, 0);
-        return;
-    }
+    assert(!mpz_is_zero(rhs));
 
     mpz_need_dig(dest_quo, lhs->len + 1); // +1 necessary?
     memset(dest_quo->dig, 0, (lhs->len + 1) * sizeof(mpz_dig_t));
@@ -1657,18 +1640,6 @@ mp_float_t mpz_as_float(const mpz_t *i) {
 }
 #endif
 
-mp_uint_t mpz_as_str_size(const mpz_t *i, mp_uint_t base, const char *prefix, char comma) {
-    if (base < 2 || base > 32) {
-        return 0;
-    }
-
-    mp_uint_t num_digits = i->len * DIG_SIZE / log_base2_floor[base] + 1;
-    mp_uint_t num_commas = comma ? num_digits / 3: 0;
-    mp_uint_t prefix_len = prefix ? strlen(prefix) : 0;
-
-    return num_digits + num_commas + prefix_len + 2; // +1 for sign, +1 for null byte
-}
-
 #if 0
 this function is unused
 char *mpz_as_str(const mpz_t *i, mp_uint_t base) {
@@ -1678,7 +1649,7 @@ char *mpz_as_str(const mpz_t *i, mp_uint_t base) {
 }
 #endif
 
-// assumes enough space as calculated by mpz_as_str_size
+// assumes enough space as calculated by mp_int_format_size
 // returns length of string, not including null byte
 mp_uint_t mpz_as_str_inpl(const mpz_t *i, mp_uint_t base, const char *prefix, char base_char, char comma, char *str) {
     if (str == NULL || base < 2 || base > 32) {
diff --git a/py/mpz.h b/py/mpz.h
index 63ac772ff..55ef3e15f 100644
--- a/py/mpz.h
+++ b/py/mpz.h
@@ -127,6 +127,7 @@ void mpz_or_inpl(mpz_t *dest, const mpz_t *lhs, const mpz_t *rhs);
 void mpz_xor_inpl(mpz_t *dest, const mpz_t *lhs, const mpz_t *rhs);
 void mpz_divmod_inpl(mpz_t *dest_quo, mpz_t *dest_rem, const mpz_t *lhs, const mpz_t *rhs);
 
+static inline size_t mpz_max_num_bits(const mpz_t *z) { return z->len * MPZ_DIG_SIZE; }
 mp_int_t mpz_hash(const mpz_t *z);
 bool mpz_as_int_checked(const mpz_t *z, mp_int_t *value);
 bool mpz_as_uint_checked(const mpz_t *z, mp_uint_t *value);
diff --git a/py/obj.c b/py/obj.c
index d6ce3dae6..72b7a216b 100644
--- a/py/obj.c
+++ b/py/obj.c
@@ -233,8 +233,7 @@ mp_int_t mp_obj_get_int(mp_const_obj_t arg) {
         return mp_obj_int_get_checked(arg);
     } else {
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "can't convert to int"));
+            mp_raise_msg(&mp_type_TypeError, "can't convert to int");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                 "can't convert %s to int", mp_obj_get_type_str(arg)));
@@ -282,8 +281,7 @@ mp_float_t mp_obj_get_float(mp_obj_t arg) {
         return mp_obj_float_get(arg);
     } else {
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "can't convert to float"));
+            mp_raise_msg(&mp_type_TypeError, "can't convert to float");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                 "can't convert %s to float", mp_obj_get_type_str(arg)));
@@ -312,8 +310,7 @@ void mp_obj_get_complex(mp_obj_t arg, mp_float_t *real, mp_float_t *imag) {
         mp_obj_complex_get(arg, real, imag);
     } else {
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "can't convert to complex"));
+            mp_raise_msg(&mp_type_TypeError, "can't convert to complex");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                 "can't convert %s to complex", mp_obj_get_type_str(arg)));
@@ -331,8 +328,7 @@ void mp_obj_get_array(mp_obj_t o, mp_uint_t *len, mp_obj_t **items) {
         mp_obj_list_get(o, len, items);
     } else {
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "expected tuple/list"));
+            mp_raise_msg(&mp_type_TypeError, "expected tuple/list");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                 "object '%s' is not a tuple or list", mp_obj_get_type_str(o)));
@@ -346,8 +342,7 @@ void mp_obj_get_array_fixed_n(mp_obj_t o, mp_uint_t len, mp_obj_t **items) {
     mp_obj_get_array(o, &seq_len, items);
     if (seq_len != len) {
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError,
-                "tuple/list has wrong length"));
+            mp_raise_msg(&mp_type_ValueError, "tuple/list has wrong length");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError,
                 "requested length %d but object has length %d", (int)len, (int)seq_len));
@@ -362,8 +357,7 @@ mp_uint_t mp_get_index(const mp_obj_type_t *type, mp_uint_t len, mp_obj_t index,
         i = MP_OBJ_SMALL_INT_VALUE(index);
     } else if (!mp_obj_get_int_maybe(index, &i)) {
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "indices must be integers"));
+            mp_raise_msg(&mp_type_TypeError, "indices must be integers");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                 "%q indices must be integers, not %s",
@@ -383,7 +377,7 @@ mp_uint_t mp_get_index(const mp_obj_type_t *type, mp_uint_t len, mp_obj_t index,
     } else {
         if (i < 0 || (mp_uint_t)i >= len) {
             if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_IndexError, "index out of range"));
+                mp_raise_msg(&mp_type_IndexError, "index out of range");
             } else {
                 nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_IndexError,
                     "%q index out of range", type->name));
@@ -416,8 +410,7 @@ mp_obj_t mp_obj_len(mp_obj_t o_in) {
     mp_obj_t len = mp_obj_len_maybe(o_in);
     if (len == MP_OBJ_NULL) {
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "object has no len"));
+            mp_raise_msg(&mp_type_TypeError, "object has no len");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                 "object of type '%s' has no len()", mp_obj_get_type_str(o_in)));
@@ -458,8 +451,7 @@ mp_obj_t mp_obj_subscr(mp_obj_t base, mp_obj_t index, mp_obj_t value) {
     }
     if (value == MP_OBJ_NULL) {
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "object does not support item deletion"));
+            mp_raise_msg(&mp_type_TypeError, "object does not support item deletion");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                 "'%s' object does not support item deletion", mp_obj_get_type_str(base)));
@@ -474,8 +466,7 @@ mp_obj_t mp_obj_subscr(mp_obj_t base, mp_obj_t index, mp_obj_t value) {
         }
     } else {
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "object does not support item assignment"));
+            mp_raise_msg(&mp_type_TypeError, "object does not support item assignment");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                 "'%s' object does not support item assignment", mp_obj_get_type_str(base)));
@@ -504,7 +495,7 @@ bool mp_get_buffer(mp_obj_t obj, mp_buffer_info_t *bufinfo, mp_uint_t flags) {
 
 void mp_get_buffer_raise(mp_obj_t obj, mp_buffer_info_t *bufinfo, mp_uint_t flags) {
     if (!mp_get_buffer(obj, bufinfo, flags)) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "object with buffer protocol required"));
+        mp_raise_msg(&mp_type_TypeError, "object with buffer protocol required");
     }
 }
 
diff --git a/py/objarray.c b/py/objarray.c
index 2cd0fef6b..8e1d32f0f 100644
--- a/py/objarray.c
+++ b/py/objarray.c
@@ -95,7 +95,7 @@ STATIC void array_print(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t
 STATIC mp_obj_array_t *array_new(char typecode, mp_uint_t n) {
     int typecode_size = mp_binary_get_size('@', typecode, NULL);
     if (typecode_size == 0) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "bad typecode"));
+        mp_raise_msg(&mp_type_ValueError, "bad typecode");
     }
     mp_obj_array_t *o = m_new_obj(mp_obj_array_t);
     #if MICROPY_PY_BUILTINS_BYTEARRAY && MICROPY_PY_ARRAY
@@ -395,7 +395,7 @@ STATIC mp_obj_t array_subscr(mp_obj_t self_in, mp_obj_t index_in, mp_obj_t value
                     mp_obj_array_t *src_slice = MP_OBJ_TO_PTR(value);
                     if (item_sz != mp_binary_get_size('@', src_slice->typecode & TYPECODE_MASK, NULL)) {
                     compat_error:
-                        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "lhs and rhs should be compatible"));
+                        mp_raise_msg(&mp_type_ValueError, "lhs and rhs should be compatible");
                     }
                     src_len = src_slice->len;
                     src_items = src_slice->items;
diff --git a/py/objcomplex.c b/py/objcomplex.c
index 5da655eb3..96be25255 100644
--- a/py/objcomplex.c
+++ b/py/objcomplex.c
@@ -197,7 +197,7 @@ mp_obj_t mp_obj_complex_binary_op(mp_uint_t op, mp_float_t lhs_real, mp_float_t
         case MP_BINARY_OP_INPLACE_TRUE_DIVIDE:
             if (rhs_imag == 0) {
                 if (rhs_real == 0) {
-                    nlr_raise(mp_obj_new_exception_msg(&mp_type_ZeroDivisionError, "complex division by zero"));
+                    mp_raise_msg(&mp_type_ZeroDivisionError, "complex division by zero");
                 }
                 lhs_real /= rhs_real;
                 lhs_imag /= rhs_real;
@@ -226,7 +226,7 @@ mp_obj_t mp_obj_complex_binary_op(mp_uint_t op, mp_float_t lhs_real, mp_float_t
                     lhs_real = 1;
                     rhs_real = 0;
                 } else {
-                    nlr_raise(mp_obj_new_exception_msg(&mp_type_ZeroDivisionError, "0.0 to a complex power"));
+                    mp_raise_msg(&mp_type_ZeroDivisionError, "0.0 to a complex power");
                 }
             } else {
                 mp_float_t ln1 = MICROPY_FLOAT_C_FUN(log)(abs1);
diff --git a/py/objdict.c b/py/objdict.c
index 7a74557dc..4942d3779 100644
--- a/py/objdict.c
+++ b/py/objdict.c
@@ -162,7 +162,7 @@ mp_obj_t mp_obj_dict_get(mp_obj_t self_in, mp_obj_t index) {
     mp_obj_dict_t *self = MP_OBJ_TO_PTR(self_in);
     mp_map_elem_t *elem = mp_map_lookup(&self->map, index, MP_MAP_LOOKUP);
     if (elem == NULL) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_KeyError, "<value>"));
+        nlr_raise(mp_obj_new_exception_arg1(&mp_type_KeyError, index));
     } else {
         return elem->value;
     }
@@ -178,7 +178,7 @@ STATIC mp_obj_t dict_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
         mp_obj_dict_t *self = MP_OBJ_TO_PTR(self_in);
         mp_map_elem_t *elem = mp_map_lookup(&self->map, index, MP_MAP_LOOKUP);
         if (elem == NULL) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_KeyError, "<value>"));
+            nlr_raise(mp_obj_new_exception_arg1(&mp_type_KeyError, index));
         } else {
             return elem->value;
         }
@@ -250,15 +250,16 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_1(dict_copy_obj, dict_copy);
 // this is a classmethod
 STATIC mp_obj_t dict_fromkeys(size_t n_args, const mp_obj_t *args) {
     mp_obj_t iter = mp_getiter(args[1]);
-    mp_obj_t len = mp_obj_len_maybe(iter);
     mp_obj_t value = mp_const_none;
     mp_obj_t next = MP_OBJ_NULL;
-    mp_obj_t self_out;
 
     if (n_args > 2) {
         value = args[2];
     }
 
+    // optimisation to allocate result based on len of argument
+    mp_obj_t self_out;
+    mp_obj_t len = mp_obj_len_maybe(args[1]);
     if (len == MP_OBJ_NULL) {
         /* object's type doesn't have a __len__ slot */
         self_out = mp_obj_new_dict(0);
@@ -282,7 +283,7 @@ STATIC mp_obj_t dict_get_helper(mp_map_t *self, mp_obj_t key, mp_obj_t deflt, mp
     if (elem == NULL || elem->value == MP_OBJ_NULL) {
         if (deflt == MP_OBJ_NULL) {
             if (lookup_kind == MP_MAP_LOOKUP_REMOVE_IF_FOUND) {
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_KeyError, "<value>"));
+                nlr_raise(mp_obj_new_exception_arg1(&mp_type_KeyError, key));
             } else {
                 value = mp_const_none;
             }
@@ -342,7 +343,7 @@ STATIC mp_obj_t dict_popitem(mp_obj_t self_in) {
     mp_uint_t cur = 0;
     mp_map_elem_t *next = dict_iter_next(self, &cur);
     if (next == NULL) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_KeyError, "popitem(): dictionary is empty"));
+        mp_raise_msg(&mp_type_KeyError, "popitem(): dictionary is empty");
     }
     self->map.used--;
     mp_obj_t items[] = {next->key, next->value};
@@ -384,9 +385,7 @@ STATIC mp_obj_t dict_update(size_t n_args, const mp_obj_t *args, mp_map_t *kwarg
                 if (key == MP_OBJ_STOP_ITERATION
                     || value == MP_OBJ_STOP_ITERATION
                     || stop != MP_OBJ_STOP_ITERATION) {
-                    nlr_raise(mp_obj_new_exception_msg(
-                                 &mp_type_ValueError,
-                                 "dictionary update sequence has the wrong length"));
+                    mp_raise_msg(&mp_type_ValueError, "dictionary update sequence has the wrong length");
                 } else {
                     mp_map_lookup(&self->map, key, MP_MAP_LOOKUP_ADD_IF_NOT_FOUND)->value = value;
                 }
diff --git a/py/objfloat.c b/py/objfloat.c
index 85b8b1386..73d07feac 100644
--- a/py/objfloat.c
+++ b/py/objfloat.c
@@ -198,7 +198,7 @@ mp_obj_t mp_obj_float_binary_op(mp_uint_t op, mp_float_t lhs_val, mp_obj_t rhs_i
         case MP_BINARY_OP_INPLACE_FLOOR_DIVIDE:
             if (rhs_val == 0) {
                 zero_division_error:
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_ZeroDivisionError, "division by zero"));
+                mp_raise_msg(&mp_type_ZeroDivisionError, "division by zero");
             }
             // Python specs require that x == (x//y)*y + (x%y) so we must
             // call divmod to compute the correct floor division, which
diff --git a/py/objgenerator.c b/py/objgenerator.c
index 8c32a3649..cbef9fea3 100644
--- a/py/objgenerator.c
+++ b/py/objgenerator.c
@@ -105,7 +105,7 @@ mp_vm_return_kind_t mp_obj_gen_resume(mp_obj_t self_in, mp_obj_t send_value, mp_
     }
     if (self->code_state.sp == self->code_state.state - 1) {
         if (send_value != mp_const_none) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "can't send non-None value to a just-started generator"));
+            mp_raise_msg(&mp_type_TypeError, "can't send non-None value to a just-started generator");
         }
     } else {
         *self->code_state.sp = send_value;
@@ -157,7 +157,7 @@ STATIC mp_obj_t gen_resume_and_raise(mp_obj_t self_in, mp_obj_t send_value, mp_o
 
         case MP_VM_RETURN_YIELD:
             if (throw_value != MP_OBJ_NULL && mp_obj_is_subclass_fast(MP_OBJ_FROM_PTR(mp_obj_get_type(throw_value)), MP_OBJ_FROM_PTR(&mp_type_GeneratorExit))) {
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_RuntimeError, "generator ignored GeneratorExit"));
+                mp_raise_msg(&mp_type_RuntimeError, "generator ignored GeneratorExit");
             }
             return ret;
 
@@ -209,7 +209,7 @@ STATIC mp_obj_t gen_instance_close(mp_obj_t self_in) {
     mp_obj_t ret;
     switch (mp_obj_gen_resume(self_in, mp_const_none, MP_OBJ_FROM_PTR(&mp_const_GeneratorExit_obj), &ret)) {
         case MP_VM_RETURN_YIELD:
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_RuntimeError, "generator ignored GeneratorExit"));
+            mp_raise_msg(&mp_type_RuntimeError, "generator ignored GeneratorExit");
 
         // Swallow StopIteration & GeneratorExit (== successful close), and re-raise any other
         case MP_VM_RETURN_EXCEPTION:
diff --git a/py/objint.c b/py/objint.c
index 9f948a145..f8988d6c9 100644
--- a/py/objint.c
+++ b/py/objint.c
@@ -133,8 +133,8 @@ void mp_obj_int_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t
     // enough, a dynamic one will be allocated.
     char stack_buf[sizeof(mp_int_t) * 4];
     char *buf = stack_buf;
-    mp_uint_t buf_size = sizeof(stack_buf);
-    mp_uint_t fmt_size;
+    size_t buf_size = sizeof(stack_buf);
+    size_t fmt_size;
 
     char *str = mp_obj_int_formatted(&buf, &buf_size, &fmt_size, self_in, 10, NULL, '\0', '\0');
     mp_print_str(print, str);
@@ -162,14 +162,14 @@ STATIC const uint8_t log_base2_floor[] = {
     4, 4, 4, 5
 };
 
-STATIC uint int_as_str_size_formatted(uint base, const char *prefix, char comma) {
+size_t mp_int_format_size(size_t num_bits, int base, const char *prefix, char comma) {
     if (base < 2 || base > 32) {
         return 0;
     }
 
-    uint num_digits = sizeof(fmt_int_t) * 8 / log_base2_floor[base] + 1;
-    uint num_commas = comma ? num_digits / 3: 0;
-    uint prefix_len = prefix ? strlen(prefix) : 0;
+    size_t num_digits = num_bits / log_base2_floor[base] + 1;
+    size_t num_commas = comma ? num_digits / 3 : 0;
+    size_t prefix_len = prefix ? strlen(prefix) : 0;
     return num_digits + num_commas + prefix_len + 2; // +1 for sign, +1 for null byte
 }
 
@@ -180,7 +180,7 @@ STATIC uint int_as_str_size_formatted(uint base, const char *prefix, char comma)
 //
 // The resulting formatted string will be returned from this function and the
 // formatted size will be in *fmt_size.
-char *mp_obj_int_formatted(char **buf, mp_uint_t *buf_size, mp_uint_t *fmt_size, mp_const_obj_t self_in,
+char *mp_obj_int_formatted(char **buf, size_t *buf_size, size_t *fmt_size, mp_const_obj_t self_in,
                            int base, const char *prefix, char base_char, char comma) {
     fmt_int_t num;
     if (MP_OBJ_IS_SMALL_INT(self_in)) {
@@ -211,7 +211,7 @@ char *mp_obj_int_formatted(char **buf, mp_uint_t *buf_size, mp_uint_t *fmt_size,
         sign = '-';
     }
 
-    uint needed_size = int_as_str_size_formatted(base, prefix, comma);
+    size_t needed_size = mp_int_format_size(sizeof(fmt_int_t) * 8, base, prefix, comma);
     if (needed_size > *buf_size) {
         *buf = m_new(char, needed_size);
         *buf_size = needed_size;
@@ -294,19 +294,19 @@ mp_obj_t mp_obj_int_binary_op(mp_uint_t op, mp_obj_t lhs_in, mp_obj_t rhs_in) {
 
 // This is called only with strings whose value doesn't fit in SMALL_INT
 mp_obj_t mp_obj_new_int_from_str_len(const char **str, mp_uint_t len, bool neg, mp_uint_t base) {
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_OverflowError, "long int not supported in this build"));
+    mp_raise_msg(&mp_type_OverflowError, "long int not supported in this build");
     return mp_const_none;
 }
 
 // This is called when an integer larger than a SMALL_INT is needed (although val might still fit in a SMALL_INT)
 mp_obj_t mp_obj_new_int_from_ll(long long val) {
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_OverflowError, "small int overflow"));
+    mp_raise_msg(&mp_type_OverflowError, "small int overflow");
     return mp_const_none;
 }
 
 // This is called when an integer larger than a SMALL_INT is needed (although val might still fit in a SMALL_INT)
 mp_obj_t mp_obj_new_int_from_ull(unsigned long long val) {
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_OverflowError, "small int overflow"));
+    mp_raise_msg(&mp_type_OverflowError, "small int overflow");
     return mp_const_none;
 }
 
@@ -316,7 +316,7 @@ mp_obj_t mp_obj_new_int_from_uint(mp_uint_t value) {
     if ((value & ~MP_SMALL_INT_POSITIVE_MASK) == 0) {
         return MP_OBJ_NEW_SMALL_INT(value);
     }
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_OverflowError, "small int overflow"));
+    mp_raise_msg(&mp_type_OverflowError, "small int overflow");
     return mp_const_none;
 }
 
@@ -342,7 +342,7 @@ mp_obj_t mp_obj_new_int(mp_int_t value) {
     if (MP_SMALL_INT_FITS(value)) {
         return MP_OBJ_NEW_SMALL_INT(value);
     }
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_OverflowError, "small int overflow"));
+    mp_raise_msg(&mp_type_OverflowError, "small int overflow");
     return mp_const_none;
 }
 
diff --git a/py/objint.h b/py/objint.h
index c79eb874a..6e627f1bd 100644
--- a/py/objint.h
+++ b/py/objint.h
@@ -50,13 +50,15 @@ typedef enum {
 mp_fp_as_int_class_t mp_classify_fp_as_int(mp_float_t val);
 #endif // MICROPY_PY_BUILTINS_FLOAT
 
+size_t mp_int_format_size(size_t num_bits, int base, const char *prefix, char comma);
+
 void mp_obj_int_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind);
-char *mp_obj_int_formatted(char **buf, mp_uint_t *buf_size, mp_uint_t *fmt_size, mp_const_obj_t self_in,
+char *mp_obj_int_formatted(char **buf, size_t *buf_size, size_t *fmt_size, mp_const_obj_t self_in,
                            int base, const char *prefix, char base_char, char comma);
-char *mp_obj_int_formatted_impl(char **buf, mp_uint_t *buf_size, mp_uint_t *fmt_size, mp_const_obj_t self_in,
+char *mp_obj_int_formatted_impl(char **buf, size_t *buf_size, size_t *fmt_size, mp_const_obj_t self_in,
                                 int base, const char *prefix, char base_char, char comma);
 mp_int_t mp_obj_int_hash(mp_obj_t self_in);
-void mp_obj_int_to_bytes_impl(mp_obj_t self_in, bool big_endian, mp_uint_t len, byte *buf);
+void mp_obj_int_to_bytes_impl(mp_obj_t self_in, bool big_endian, size_t len, byte *buf);
 int mp_obj_int_sign(mp_obj_t self_in);
 mp_obj_t mp_obj_int_abs(mp_obj_t self_in);
 mp_obj_t mp_obj_int_unary_op(mp_uint_t op, mp_obj_t o_in);
diff --git a/py/objint_longlong.c b/py/objint_longlong.c
index f10e46447..b051cfbe6 100644
--- a/py/objint_longlong.c
+++ b/py/objint_longlong.c
@@ -53,7 +53,7 @@
 const mp_obj_int_t mp_maxsize_obj = {{&mp_type_int}, MP_SSIZE_MAX};
 #endif
 
-void mp_obj_int_to_bytes_impl(mp_obj_t self_in, bool big_endian, mp_uint_t len, byte *buf) {
+void mp_obj_int_to_bytes_impl(mp_obj_t self_in, bool big_endian, size_t len, byte *buf) {
     assert(MP_OBJ_IS_TYPE(self_in, &mp_type_int));
     mp_obj_int_t *self = self_in;
     long long val = self->val;
diff --git a/py/objint_mpz.c b/py/objint_mpz.c
index 3a30eb9d9..0a1d68598 100644
--- a/py/objint_mpz.c
+++ b/py/objint_mpz.c
@@ -90,12 +90,12 @@ STATIC mp_obj_int_t *mp_obj_int_new_mpz(void) {
 // formatted size will be in *fmt_size.
 //
 // This particular routine should only be called for the mpz representation of the int.
-char *mp_obj_int_formatted_impl(char **buf, mp_uint_t *buf_size, mp_uint_t *fmt_size, mp_const_obj_t self_in,
+char *mp_obj_int_formatted_impl(char **buf, size_t *buf_size, size_t *fmt_size, mp_const_obj_t self_in,
                                 int base, const char *prefix, char base_char, char comma) {
     assert(MP_OBJ_IS_TYPE(self_in, &mp_type_int));
     const mp_obj_int_t *self = MP_OBJ_TO_PTR(self_in);
 
-    mp_uint_t needed_size = mpz_as_str_size(&self->mpz, base, prefix, comma);
+    size_t needed_size = mp_int_format_size(mpz_max_num_bits(&self->mpz), base, prefix, comma);
     if (needed_size > *buf_size) {
         *buf = m_new(char, needed_size);
         *buf_size = needed_size;
@@ -107,7 +107,7 @@ char *mp_obj_int_formatted_impl(char **buf, mp_uint_t *buf_size, mp_uint_t *fmt_
     return str;
 }
 
-void mp_obj_int_to_bytes_impl(mp_obj_t self_in, bool big_endian, mp_uint_t len, byte *buf) {
+void mp_obj_int_to_bytes_impl(mp_obj_t self_in, bool big_endian, size_t len, byte *buf) {
     assert(MP_OBJ_IS_TYPE(self_in, &mp_type_int));
     mp_obj_int_t *self = MP_OBJ_TO_PTR(self_in);
     mpz_as_bytes(&self->mpz, big_endian, len, buf);
@@ -234,8 +234,7 @@ mp_obj_t mp_obj_int_binary_op(mp_uint_t op, mp_obj_t lhs_in, mp_obj_t rhs_in) {
             case MP_BINARY_OP_INPLACE_FLOOR_DIVIDE: {
                 if (mpz_is_zero(zrhs)) {
                     zero_division_error:
-                    nlr_raise(mp_obj_new_exception_msg(&mp_type_ZeroDivisionError,
-                        "division by zero"));
+                    mp_raise_msg(&mp_type_ZeroDivisionError, "division by zero");
                 }
                 mpz_t rem; mpz_init_zero(&rem);
                 mpz_divmod_inpl(&res->mpz, &rem, zlhs, zrhs);
@@ -272,7 +271,7 @@ mp_obj_t mp_obj_int_binary_op(mp_uint_t op, mp_obj_t lhs_in, mp_obj_t rhs_in) {
             case MP_BINARY_OP_INPLACE_RSHIFT: {
                 mp_int_t irhs = mp_obj_int_get_checked(rhs_in);
                 if (irhs < 0) {
-                    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "negative shift count"));
+                    mp_raise_msg(&mp_type_ValueError, "negative shift count");
                 }
                 if (op == MP_BINARY_OP_LSHIFT || op == MP_BINARY_OP_INPLACE_LSHIFT) {
                     mpz_shl_inpl(&res->mpz, zlhs, irhs);
@@ -398,7 +397,7 @@ mp_int_t mp_obj_int_get_checked(mp_const_obj_t self_in) {
             return value;
         } else {
             // overflow
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_OverflowError, "overflow converting long int to machine word"));
+            mp_raise_msg(&mp_type_OverflowError, "overflow converting long int to machine word");
         }
     }
 }
diff --git a/py/objlist.c b/py/objlist.c
index b5e8b9965..6d4a20a50 100644
--- a/py/objlist.c
+++ b/py/objlist.c
@@ -266,7 +266,7 @@ STATIC mp_obj_t list_pop(size_t n_args, const mp_obj_t *args) {
     mp_check_self(MP_OBJ_IS_TYPE(args[0], &mp_type_list));
     mp_obj_list_t *self = MP_OBJ_TO_PTR(args[0]);
     if (self->len == 0) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_IndexError, "pop from empty list"));
+        mp_raise_msg(&mp_type_IndexError, "pop from empty list");
     }
     mp_uint_t index = mp_get_index(self->base.type, self->len, n_args == 1 ? MP_OBJ_NEW_SMALL_INT(-1) : args[1], false);
     mp_obj_t ret = self->items[index];
diff --git a/py/objnamedtuple.c b/py/objnamedtuple.c
index 38cda1ad7..18931a16c 100644
--- a/py/objnamedtuple.c
+++ b/py/objnamedtuple.c
@@ -73,7 +73,7 @@ STATIC void namedtuple_attr(mp_obj_t self_in, qstr attr, mp_obj_t *dest) {
     } else {
         // delete/store attribute
         // provide more detailed error message than we'd get by just returning
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_AttributeError, "can't set attribute"));
+        mp_raise_msg(&mp_type_AttributeError, "can't set attribute");
     }
 }
 
diff --git a/py/objobject.c b/py/objobject.c
index bba6f053e..b33dc491c 100644
--- a/py/objobject.c
+++ b/py/objobject.c
@@ -50,8 +50,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_1(object___init___obj, object___init__);
 
 STATIC mp_obj_t object___new__(mp_obj_t cls) {
     if (!MP_OBJ_IS_TYPE(cls, &mp_type_type) || !mp_obj_is_instance_type((mp_obj_type_t*)MP_OBJ_TO_PTR(cls))) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                    "__new__ arg must be a user-type"));
+        mp_raise_msg(&mp_type_TypeError, "__new__ arg must be a user-type");
     }
     mp_obj_t o = MP_OBJ_SENTINEL;
     mp_obj_t res = mp_obj_instance_make_new(MP_OBJ_TO_PTR(cls), 1, 0, &o);
diff --git a/py/objset.c b/py/objset.c
index 6b6f95f9b..fc124fcd8 100644
--- a/py/objset.c
+++ b/py/objset.c
@@ -68,7 +68,7 @@ STATIC void check_set(mp_obj_t o) {
     if (MP_OBJ_IS_TYPE(o, &mp_type_frozenset)) {
         // Mutable method called on frozenset; emulate CPython behavior, eg:
         // AttributeError: 'frozenset' object has no attribute 'add'
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_AttributeError, "'frozenset' has no such attribute"));
+        mp_raise_msg(&mp_type_AttributeError, "'frozenset' has no such attribute");
     }
     #endif
     mp_check_self(MP_OBJ_IS_TYPE(o, &mp_type_set));
@@ -389,7 +389,7 @@ STATIC mp_obj_t set_pop(mp_obj_t self_in) {
     mp_obj_set_t *self = MP_OBJ_TO_PTR(self_in);
     mp_obj_t obj = mp_set_remove_first(&self->set);
     if (obj == MP_OBJ_NULL) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_KeyError, "pop from an empty set"));
+        mp_raise_msg(&mp_type_KeyError, "pop from an empty set");
     }
     return obj;
 }
diff --git a/py/objstringio.c b/py/objstringio.c
index eb0cc4eb3..a430fca3b 100644
--- a/py/objstringio.c
+++ b/py/objstringio.c
@@ -30,22 +30,16 @@
 
 #include "py/nlr.h"
 #include "py/objstr.h"
+#include "py/objstringio.h"
 #include "py/runtime.h"
 #include "py/stream.h"
 
 #if MICROPY_PY_IO
 
-typedef struct _mp_obj_stringio_t {
-    mp_obj_base_t base;
-    vstr_t *vstr;
-    // StringIO has single pointer used for both reading and writing
-    mp_uint_t pos;
-} mp_obj_stringio_t;
-
 #if MICROPY_CPYTHON_COMPAT
 STATIC void check_stringio_is_open(const mp_obj_stringio_t *o) {
     if (o->vstr == NULL) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "I/O operation on closed file"));
+        mp_raise_msg(&mp_type_ValueError, "I/O operation on closed file");
     }
 }
 #else
@@ -156,7 +150,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(stringio___exit___obj, 4, 4, stringio
 STATIC mp_obj_stringio_t *stringio_new(const mp_obj_type_t *type) {
     mp_obj_stringio_t *o = m_new_obj(mp_obj_stringio_t);
     o->base.type = type;
-    o->vstr = vstr_new();
+    o->vstr = vstr_new(16);
     o->pos = 0;
     return o;
 }
diff --git a/py/objstringio.h b/py/objstringio.h
new file mode 100644
index 000000000..853bfb11b
--- /dev/null
+++ b/py/objstringio.h
@@ -0,0 +1,38 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016 Damien P. George
+ *
+ * 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.
+ */
+#ifndef MICROPY_INCLUDED_PY_OBJSTRINGIO_H
+#define MICROPY_INCLUDED_PY_OBJSTRINGIO_H
+
+#include "py/obj.h"
+
+typedef struct _mp_obj_stringio_t {
+    mp_obj_base_t base;
+    vstr_t *vstr;
+    // StringIO has single pointer used for both reading and writing
+    mp_uint_t pos;
+} mp_obj_stringio_t;
+
+#endif // MICROPY_INCLUDED_PY_OBJSTRINGIO_H
diff --git a/py/objtype.c b/py/objtype.c
index 907308a75..8b46c5400 100644
--- a/py/objtype.c
+++ b/py/objtype.c
@@ -311,8 +311,7 @@ mp_obj_t mp_obj_instance_make_new(const mp_obj_type_t *self, size_t n_args, size
         }
         if (init_ret != mp_const_none) {
             if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                    "__init__() should return None"));
+                mp_raise_msg(&mp_type_TypeError, "__init__() should return None");
             } else {
                 nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                     "__init__() should return None, not '%s'", mp_obj_get_type_str(init_ret)));
@@ -508,7 +507,7 @@ STATIC void mp_obj_instance_load_attr(mp_obj_t self_in, qstr attr, mp_obj_t *des
             // the code.
             const mp_obj_t *proxy = mp_obj_property_get(member);
             if (proxy[0] == mp_const_none) {
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_AttributeError, "unreadable attribute"));
+                mp_raise_msg(&mp_type_AttributeError, "unreadable attribute");
             } else {
                 dest[0] = mp_call_function_n_kw(proxy[0], 1, 0, &self_in);
             }
@@ -710,8 +709,7 @@ mp_obj_t mp_obj_instance_call(mp_obj_t self_in, size_t n_args, size_t n_kw, cons
     mp_obj_t call = mp_obj_instance_get_call(self_in);
     if (call == MP_OBJ_NULL) {
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "object not callable"));
+            mp_raise_msg(&mp_type_TypeError, "object not callable");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                 "'%s' object is not callable", mp_obj_get_type_str(self_in)));
@@ -793,7 +791,7 @@ STATIC mp_obj_t type_make_new(const mp_obj_type_t *type_in, size_t n_args, size_
             return mp_obj_new_type(mp_obj_str_get_qstr(args[0]), args[1], args[2]);
 
         default:
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "type takes 1 or 3 arguments"));
+            mp_raise_msg(&mp_type_TypeError, "type takes 1 or 3 arguments");
     }
 }
 
@@ -804,7 +802,7 @@ STATIC mp_obj_t type_call(mp_obj_t self_in, size_t n_args, size_t n_kw, const mp
 
     if (self->make_new == NULL) {
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "cannot create instance"));
+            mp_raise_msg(&mp_type_TypeError, "cannot create instance");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                 "cannot create '%q' instances", self->name));
@@ -892,8 +890,7 @@ mp_obj_t mp_obj_new_type(qstr name, mp_obj_t bases_tuple, mp_obj_t locals_dict)
         // TODO: Verify with CPy, tested on function type
         if (t->make_new == NULL) {
             if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                    "type is not an acceptable base type"));
+                mp_raise_msg(&mp_type_TypeError, "type is not an acceptable base type");
             } else {
                 nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                     "type '%q' is not an acceptable base type", t->name));
@@ -927,7 +924,7 @@ mp_obj_t mp_obj_new_type(qstr name, mp_obj_t bases_tuple, mp_obj_t locals_dict)
     const mp_obj_type_t *native_base;
     uint num_native_bases = instance_count_native_bases(o, &native_base);
     if (num_native_bases > 1) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "multiple bases have instance lay-out conflict"));
+        mp_raise_msg(&mp_type_TypeError, "multiple bases have instance lay-out conflict");
     }
 
     mp_map_t *locals_map = &o->locals_dict->map;
@@ -1074,7 +1071,7 @@ STATIC mp_obj_t mp_obj_is_subclass(mp_obj_t object, mp_obj_t classinfo) {
     } else if (MP_OBJ_IS_TYPE(classinfo, &mp_type_tuple)) {
         mp_obj_tuple_get(classinfo, &len, &items);
     } else {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "issubclass() arg 2 must be a class or a tuple of classes"));
+        mp_raise_msg(&mp_type_TypeError, "issubclass() arg 2 must be a class or a tuple of classes");
     }
 
     for (uint i = 0; i < len; i++) {
@@ -1088,7 +1085,7 @@ STATIC mp_obj_t mp_obj_is_subclass(mp_obj_t object, mp_obj_t classinfo) {
 
 STATIC mp_obj_t mp_builtin_issubclass(mp_obj_t object, mp_obj_t classinfo) {
     if (!MP_OBJ_IS_TYPE(object, &mp_type_type)) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "issubclass() arg 1 must be a class"));
+        mp_raise_msg(&mp_type_TypeError, "issubclass() arg 1 must be a class");
     }
     return mp_obj_is_subclass(object, classinfo);
 }
diff --git a/py/parsenum.c b/py/parsenum.c
index 83a6abd20..1010ad305 100644
--- a/py/parsenum.c
+++ b/py/parsenum.c
@@ -27,7 +27,7 @@
 #include <stdbool.h>
 #include <stdlib.h>
 
-#include "py/nlr.h"
+#include "py/runtime.h"
 #include "py/parsenumbase.h"
 #include "py/parsenum.h"
 #include "py/smallint.h"
@@ -55,7 +55,7 @@ mp_obj_t mp_parse_num_integer(const char *restrict str_, size_t len, int base, m
     // check radix base
     if ((base != 0 && base < 2) || base > 36) {
         // this won't be reached if lex!=NULL
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "int() arg 2 must be >= 2 and <= 36"));
+        mp_raise_msg(&mp_type_ValueError, "int() arg 2 must be >= 2 and <= 36");
     }
 
     // skip leading space
diff --git a/py/py.mk b/py/py.mk
index 741ad52f9..ab07bbbde 100644
--- a/py/py.mk
+++ b/py/py.mk
@@ -229,6 +229,7 @@ PY_O_BASENAME = \
 	../extmod/vfs_fat_file.o \
 	../extmod/vfs_fat_lexer.o \
 	../extmod/vfs_fat_misc.o \
+	../extmod/utime_mphal.o \
 	../extmod/moduos_dupterm.o \
 	../lib/embed/abort_.o \
 	../lib/utils/printf.o \
@@ -236,6 +237,10 @@ PY_O_BASENAME = \
 # prepend the build destination prefix to the py object files
 PY_O = $(addprefix $(PY_BUILD)/, $(PY_O_BASENAME))
 
+ifneq ($(FROZEN_DIR),)
+PY_O += $(BUILD)/$(BUILD)/frozen.o
+endif
+
 # Sources that may contain qstrings
 SRC_QSTR_IGNORE = nlr% emitnx% emitnthumb% emitnarm%
 SRC_QSTR = $(SRC_MOD) $(addprefix py/,$(filter-out $(SRC_QSTR_IGNORE),$(PY_O_BASENAME:.o=.c)) emitnative.c)
diff --git a/py/runtime.c b/py/runtime.c
index 003c9f8b4..6eda77ee9 100644
--- a/py/runtime.c
+++ b/py/runtime.c
@@ -138,8 +138,7 @@ mp_obj_t mp_load_global(qstr qst) {
         elem = mp_map_lookup((mp_map_t*)&mp_module_builtins_globals.map, MP_OBJ_NEW_QSTR(qst), MP_MAP_LOOKUP);
         if (elem == NULL) {
             if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_NameError,
-                    "name not defined"));
+                mp_raise_msg(&mp_type_NameError, "name not defined");
             } else {
                 nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_NameError,
                     "name '%q' is not defined", qst));
@@ -230,8 +229,7 @@ mp_obj_t mp_unary_op(mp_uint_t op, mp_obj_t arg) {
             }
         }
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "unsupported type for operator"));
+            mp_raise_msg(&mp_type_TypeError, "unsupported type for operator");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                 "unsupported type for %q: '%s'",
@@ -323,7 +321,7 @@ mp_obj_t mp_binary_op(mp_uint_t op, mp_obj_t lhs, mp_obj_t rhs) {
                 case MP_BINARY_OP_INPLACE_LSHIFT: {
                     if (rhs_val < 0) {
                         // negative shift not allowed
-                        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "negative shift count"));
+                        mp_raise_msg(&mp_type_ValueError, "negative shift count");
                     } else if (rhs_val >= (mp_int_t)BITS_PER_WORD || lhs_val > (MP_SMALL_INT_MAX >> rhs_val) || lhs_val < (MP_SMALL_INT_MIN >> rhs_val)) {
                         // left-shift will overflow, so use higher precision integer
                         lhs = mp_obj_new_int_from_ll(lhs_val);
@@ -338,7 +336,7 @@ mp_obj_t mp_binary_op(mp_uint_t op, mp_obj_t lhs, mp_obj_t rhs) {
                 case MP_BINARY_OP_INPLACE_RSHIFT:
                     if (rhs_val < 0) {
                         // negative shift not allowed
-                        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "negative shift count"));
+                        mp_raise_msg(&mp_type_ValueError, "negative shift count");
                     } else {
                         // standard precision is enough for right-shift
                         if (rhs_val >= (mp_int_t)BITS_PER_WORD) {
@@ -414,7 +412,7 @@ mp_obj_t mp_binary_op(mp_uint_t op, mp_obj_t lhs, mp_obj_t rhs) {
                         lhs = mp_obj_new_float(lhs_val);
                         goto generic_binary_op;
                         #else
-                        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "negative power with no float support"));
+                        mp_raise_msg(&mp_type_ValueError, "negative power with no float support");
                         #endif
                     } else {
                         mp_int_t ans = 1;
@@ -515,8 +513,7 @@ mp_obj_t mp_binary_op(mp_uint_t op, mp_obj_t lhs, mp_obj_t rhs) {
         }
 
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "object not iterable"));
+            mp_raise_msg(&mp_type_TypeError, "object not iterable");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                 "'%s' object is not iterable", mp_obj_get_type_str(rhs)));
@@ -538,8 +535,7 @@ generic_binary_op:
 
 unsupported_op:
     if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-            "unsupported type for operator"));
+        mp_raise_msg(&mp_type_TypeError, "unsupported type for operator");
     } else {
         nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
             "unsupported types for %q: '%s', '%s'",
@@ -547,7 +543,7 @@ unsupported_op:
     }
 
 zero_division:
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_ZeroDivisionError, "division by zero"));
+    mp_raise_msg(&mp_type_ZeroDivisionError, "division by zero");
 }
 
 mp_obj_t mp_call_function_0(mp_obj_t fun) {
@@ -581,8 +577,7 @@ mp_obj_t mp_call_function_n_kw(mp_obj_t fun_in, mp_uint_t n_args, mp_uint_t n_kw
     }
 
     if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-            "object not callable"));
+        mp_raise_msg(&mp_type_TypeError, "object not callable");
     } else {
         nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
             "'%s' object is not callable", mp_obj_get_type_str(fun_in)));
@@ -813,16 +808,14 @@ void mp_unpack_sequence(mp_obj_t seq_in, mp_uint_t num, mp_obj_t *items) {
 
 too_short:
     if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError,
-            "wrong number of values to unpack"));
+        mp_raise_msg(&mp_type_ValueError, "wrong number of values to unpack");
     } else {
         nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError,
             "need more than %d values to unpack", (int)seq_len));
     }
 too_long:
     if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError,
-            "wrong number of values to unpack"));
+        mp_raise_msg(&mp_type_ValueError, "wrong number of values to unpack");
     } else {
         nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError,
             "too many values to unpack (expected %d)", (int)num));
@@ -888,8 +881,7 @@ void mp_unpack_ex(mp_obj_t seq_in, mp_uint_t num_in, mp_obj_t *items) {
 
 too_short:
     if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError,
-            "wrong number of values to unpack"));
+        mp_raise_msg(&mp_type_ValueError, "wrong number of values to unpack");
     } else {
         nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError,
             "need more than %d values to unpack", (int)seq_len));
@@ -928,8 +920,7 @@ STATIC mp_obj_t checked_fun_call(mp_obj_t self_in, size_t n_args, size_t n_kw, c
         const mp_obj_type_t *arg0_type = mp_obj_get_type(args[0]);
         if (arg0_type != self->type) {
             if (MICROPY_ERROR_REPORTING != MICROPY_ERROR_REPORTING_DETAILED) {
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                    "argument has wrong type"));
+                mp_raise_msg(&mp_type_TypeError, "argument has wrong type");
             } else {
                 nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                     "argument should be a '%q' not a '%q'", self->type->name, arg0_type->name));
@@ -1045,8 +1036,7 @@ void mp_load_method(mp_obj_t base, qstr attr, mp_obj_t *dest) {
     if (dest[0] == MP_OBJ_NULL) {
         // no attribute/method called attr
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_AttributeError,
-                "no such attribute"));
+            mp_raise_msg(&mp_type_AttributeError, "no such attribute");
         } else {
             // following CPython, we give a more detailed error message for type objects
             if (MP_OBJ_IS_TYPE(base, &mp_type_type)) {
@@ -1074,8 +1064,7 @@ void mp_store_attr(mp_obj_t base, qstr attr, mp_obj_t value) {
         }
     }
     if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_AttributeError,
-            "no such attribute"));
+        mp_raise_msg(&mp_type_AttributeError, "no such attribute");
     } else {
         nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_AttributeError,
             "'%s' object has no attribute '%q'",
@@ -1105,8 +1094,7 @@ mp_obj_t mp_getiter(mp_obj_t o_in) {
 
     // object not iterable
     if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-            "object not iterable"));
+        mp_raise_msg(&mp_type_TypeError, "object not iterable");
     } else {
         nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
             "'%s' object is not iterable", mp_obj_get_type_str(o_in)));
@@ -1128,8 +1116,7 @@ mp_obj_t mp_iternext_allow_raise(mp_obj_t o_in) {
             return mp_call_method_n_kw(0, 0, dest);
         } else {
             if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                    "object not an iterator"));
+                mp_raise_msg(&mp_type_TypeError, "object not an iterator");
             } else {
                 nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                     "'%s' object is not an iterator", mp_obj_get_type_str(o_in)));
@@ -1165,8 +1152,7 @@ mp_obj_t mp_iternext(mp_obj_t o_in) {
             }
         } else {
             if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                    "object not an iterator"));
+                mp_raise_msg(&mp_type_TypeError, "object not an iterator");
             } else {
                 nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                     "'%s' object is not an iterator", mp_obj_get_type_str(o_in)));
@@ -1384,8 +1370,7 @@ void *m_malloc_fail(size_t num_bytes) {
         // dummy
     #if MICROPY_ENABLE_GC
     } else if (gc_is_locked()) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_MemoryError,
-                                           "memory allocation failed, heap is locked"));
+        mp_raise_msg(&mp_type_MemoryError, "memory allocation failed, heap is locked");
     #endif
     } else {
         nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_MemoryError,
diff --git a/py/sequence.c b/py/sequence.c
index 239f1b2cc..0acdd25be 100644
--- a/py/sequence.c
+++ b/py/sequence.c
@@ -235,7 +235,7 @@ mp_obj_t mp_seq_index_obj(const mp_obj_t *items, mp_uint_t len, mp_uint_t n_args
         }
     }
 
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "object not in sequence"));
+    mp_raise_msg(&mp_type_ValueError, "object not in sequence");
 }
 
 mp_obj_t mp_seq_count_obj(const mp_obj_t *items, mp_uint_t len, mp_obj_t value) {
diff --git a/py/stream.c b/py/stream.c
index 5610faf74..cc8a63ac2 100644
--- a/py/stream.c
+++ b/py/stream.c
@@ -101,7 +101,7 @@ const mp_stream_p_t *mp_get_stream_raise(mp_obj_t self_in, int flags) {
         || ((flags & MP_STREAM_OP_WRITE) && stream_p->write == NULL)
         || ((flags & MP_STREAM_OP_IOCTL) && stream_p->ioctl == NULL)) {
         // CPython: io.UnsupportedOperation, OSError subclass
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, "stream operation not supported"));
+        mp_raise_msg(&mp_type_OSError, "stream operation not supported");
     }
     return stream_p;
 }
diff --git a/py/vstr.c b/py/vstr.c
index 5096475f1..6a91552b5 100644
--- a/py/vstr.c
+++ b/py/vstr.c
@@ -74,20 +74,8 @@ void vstr_clear(vstr_t *vstr) {
     vstr->buf = NULL;
 }
 
-vstr_t *vstr_new(void) {
+vstr_t *vstr_new(size_t alloc) {
     vstr_t *vstr = m_new_obj(vstr_t);
-    if (vstr == NULL) {
-        return NULL;
-    }
-    vstr_init(vstr, 16);
-    return vstr;
-}
-
-vstr_t *vstr_new_size(size_t alloc) {
-    vstr_t *vstr = m_new_obj(vstr_t);
-    if (vstr == NULL) {
-        return NULL;
-    }
     vstr_init(vstr, alloc);
     return vstr;
 }