diff --git a/ports/atmel-samd/spi_flash.c b/ports/atmel-samd/spi_flash.c
index a64c0ed331..1070481ea8 100644
--- a/ports/atmel-samd/spi_flash.c
+++ b/ports/atmel-samd/spi_flash.c
@@ -30,7 +30,7 @@
 
 #include "extmod/vfs.h"
 #include "extmod/vfs_fat.h"
-#include "py/gc.h"
+#include "py/misc.h"
 #include "py/obj.h"
 #include "py/runtime.h"
 #include "lib/oofatfs/ff.h"
@@ -256,12 +256,12 @@ void spi_flash_init(void) {
     if (spi_flash_is_initialised) {
         return;
     }
-        
+
     samd_peripherals_sercom_clock_init(SPI_FLASH_SERCOM, SPI_FLASH_SERCOM_INDEX);
 
     // Set up with defaults, then change.
     spi_m_sync_init(&spi_flash_desc, SPI_FLASH_SERCOM);
-        
+
     hri_sercomspi_write_CTRLA_DOPO_bf(SPI_FLASH_SERCOM, SPI_FLASH_DOPO);
     hri_sercomspi_write_CTRLA_DIPO_bf(SPI_FLASH_SERCOM, SPI_FLASH_DIPO);
 
@@ -398,7 +398,7 @@ static bool flush_scratch_flash(void) {
 static bool allocate_ram_cache(void) {
     uint8_t blocks_per_sector = SPI_FLASH_ERASE_SIZE / FILESYSTEM_BLOCK_SIZE;
     uint8_t pages_per_block = FILESYSTEM_BLOCK_SIZE / SPI_FLASH_PAGE_SIZE;
-    MP_STATE_VM(flash_ram_cache) = gc_alloc(blocks_per_sector * pages_per_block * sizeof(uint32_t), false);
+    MP_STATE_VM(flash_ram_cache) = m_malloc_maybe(blocks_per_sector * pages_per_block * sizeof(uint32_t), false);
     if (MP_STATE_VM(flash_ram_cache) == NULL) {
         return false;
     }
@@ -409,7 +409,7 @@ static bool allocate_ram_cache(void) {
     bool success = true;
     for (i = 0; i < blocks_per_sector; i++) {
         for (j = 0; j < pages_per_block; j++) {
-            uint8_t *page_cache = gc_alloc(SPI_FLASH_PAGE_SIZE, false);
+            uint8_t *page_cache = m_malloc_maybe(SPI_FLASH_PAGE_SIZE, false);
             if (page_cache == NULL) {
                 success = false;
                 break;
@@ -427,11 +427,11 @@ static bool allocate_ram_cache(void) {
         i++;
         for (; i > 0; i--) {
             for (; j > 0; j--) {
-                gc_free(MP_STATE_VM(flash_ram_cache)[(i - 1) * pages_per_block + (j - 1)]);
+                m_free(MP_STATE_VM(flash_ram_cache)[(i - 1) * pages_per_block + (j - 1)]);
             }
             j = pages_per_block;
         }
-        gc_free(MP_STATE_VM(flash_ram_cache));
+        m_free(MP_STATE_VM(flash_ram_cache));
         MP_STATE_VM(flash_ram_cache) = NULL;
     }
     return success;
@@ -474,13 +474,13 @@ static bool flush_ram_cache(bool keep_cache) {
                         MP_STATE_VM(flash_ram_cache)[i * pages_per_block + j],
                         SPI_FLASH_PAGE_SIZE);
             if (!keep_cache) {
-                gc_free(MP_STATE_VM(flash_ram_cache)[i * pages_per_block + j]);
+                m_free(MP_STATE_VM(flash_ram_cache)[i * pages_per_block + j]);
             }
         }
     }
     // We're done with the cache for now so give it back.
     if (!keep_cache) {
-        gc_free(MP_STATE_VM(flash_ram_cache));
+        m_free(MP_STATE_VM(flash_ram_cache));
         MP_STATE_VM(flash_ram_cache) = NULL;
     }
     return true;
diff --git a/py/builtinimport.c b/py/builtinimport.c
index b76ea00bd8..9f7d34dcae 100644
--- a/py/builtinimport.c
+++ b/py/builtinimport.c
@@ -30,6 +30,7 @@
 #include <assert.h>
 
 #include "py/compile.h"
+#include "py/gc_long_lived.h"
 #include "py/objmodule.h"
 #include "py/persistentcode.h"
 #include "py/runtime.h"
@@ -144,6 +145,7 @@ STATIC void do_load_from_lexer(mp_obj_t module_obj, mp_lexer_t *lex) {
     // parse, compile and execute the module in its context
     mp_obj_dict_t *mod_globals = mp_obj_module_get_globals(module_obj);
     mp_parse_compile_execute(lex, MP_PARSE_FILE_INPUT, mod_globals, mod_globals);
+    mp_obj_module_set_globals(module_obj, make_dict_long_lived(mod_globals, 10));
 }
 #endif
 
@@ -173,6 +175,8 @@ STATIC void do_execute_raw_code(mp_obj_t module_obj, mp_raw_code_t *raw_code) {
 
         // finish nlr block, restore context
         nlr_pop();
+        mp_obj_module_set_globals(module_obj,
+            make_dict_long_lived(mp_obj_module_get_globals(module_obj), 10));
         mp_globals_set(old_globals);
         mp_locals_set(old_locals);
     } else {
@@ -468,6 +472,10 @@ mp_obj_t mp_builtin___import__(size_t n_args, const mp_obj_t *args) {
             if (outer_module_obj != MP_OBJ_NULL) {
                 qstr s = qstr_from_strn(mod_str + last, i - last);
                 mp_store_attr(outer_module_obj, s, module_obj);
+                // The above store can cause a dictionary rehash and new allocation. So,
+                // lets make sure the globals dictionary is still long lived.
+                mp_obj_module_set_globals(outer_module_obj,
+                    make_dict_long_lived(mp_obj_module_get_globals(outer_module_obj), 10));
             }
             outer_module_obj = module_obj;
             if (top_module_obj == MP_OBJ_NULL) {
diff --git a/py/gc.c b/py/gc.c
index 16b6e01927..2c2354e4c0 100644
--- a/py/gc.c
+++ b/py/gc.c
@@ -41,6 +41,9 @@
 #define DEBUG_printf(...) (void)0
 #endif
 
+// Uncomment this if you want to use a debugger to capture state at every allocation and free.
+// #define LOG_HEAP_ACTIVITY 1
+
 // make this 1 to dump the heap each time it changes
 #define EXTENSIVE_HEAP_PROFILING (0)
 
@@ -59,15 +62,6 @@
 #define AT_MARK (3)
 
 #define BLOCKS_PER_ATB (4)
-#define ATB_MASK_0 (0x03)
-#define ATB_MASK_1 (0x0c)
-#define ATB_MASK_2 (0x30)
-#define ATB_MASK_3 (0xc0)
-
-#define ATB_0_IS_FREE(a) (((a) & ATB_MASK_0) == 0)
-#define ATB_1_IS_FREE(a) (((a) & ATB_MASK_1) == 0)
-#define ATB_2_IS_FREE(a) (((a) & ATB_MASK_2) == 0)
-#define ATB_3_IS_FREE(a) (((a) & ATB_MASK_3) == 0)
 
 #define BLOCK_SHIFT(block) (2 * ((block) & (BLOCKS_PER_ATB - 1)))
 #define ATB_GET_KIND(block) ((MP_STATE_MEM(gc_alloc_table_start)[(block) / BLOCKS_PER_ATB] >> BLOCK_SHIFT(block)) & 3)
@@ -152,14 +146,19 @@ void gc_init(void *start, void *end) {
     memset(MP_STATE_MEM(gc_finaliser_table_start), 0, gc_finaliser_table_byte_len);
 #endif
 
-    // set last free ATB index to start of heap
-    MP_STATE_MEM(gc_last_free_atb_index) = 0;
+    // Set first free ATB index to the start of the heap.
+    MP_STATE_MEM(gc_first_free_atb_index) = 0;
+    // Set last free ATB index to the end of the heap.
+    MP_STATE_MEM(gc_last_free_atb_index) = MP_STATE_MEM(gc_alloc_table_byte_len) - 1;
+    // Set the lowest long lived ptr to the end of the heap to start. This will be lowered as long
+    // lived objects are allocated.
+    MP_STATE_MEM(gc_lowest_long_lived_ptr) = (void*) PTR_FROM_BLOCK(MP_STATE_MEM(gc_alloc_table_byte_len * BLOCKS_PER_ATB));
 
     // unlock the GC
     MP_STATE_MEM(gc_lock_depth) = 0;
 
     // allow auto collection
-    MP_STATE_MEM(gc_auto_collect_enabled) = 1;
+    MP_STATE_MEM(gc_auto_collect_enabled) = true;
 
     #if MICROPY_GC_ALLOC_THRESHOLD
     // by default, maxuint for gc threshold, effectively turning gc-by-threshold off
@@ -288,6 +287,7 @@ STATIC void gc_sweep(void) {
                 }
 #endif
                 free_tail = 1;
+                ATB_ANY_TO_FREE(block);
                 DEBUG_printf("gc_sweep(%x)\n", PTR_FROM_BLOCK(block));
 
                 #ifdef LOG_HEAP_ACTIVITY
@@ -296,7 +296,7 @@ STATIC void gc_sweep(void) {
                 #if MICROPY_PY_GC_COLLECT_RETVAL
                 MP_STATE_MEM(gc_collected)++;
                 #endif
-                // fall through to free the head
+                break;
 
             case AT_TAIL:
                 if (free_tail) {
@@ -338,7 +338,8 @@ void gc_collect_root(void **ptrs, size_t len) {
 void gc_collect_end(void) {
     gc_deal_with_stack_overflow();
     gc_sweep();
-    MP_STATE_MEM(gc_last_free_atb_index) = 0;
+    MP_STATE_MEM(gc_first_free_atb_index) = 0;
+    MP_STATE_MEM(gc_last_free_atb_index) = MP_STATE_MEM(gc_alloc_table_byte_len) - 1;
     MP_STATE_MEM(gc_lock_depth)--;
     GC_EXIT();
 }
@@ -407,7 +408,9 @@ void gc_info(gc_info_t *info) {
     GC_EXIT();
 }
 
-void *gc_alloc(size_t n_bytes, bool has_finaliser) {
+// We place long lived objects at the end of the heap rather than the start. This reduces
+// fragmentation by localizing the heap churn to one portion of memory (the start of the heap.)
+void *gc_alloc(size_t n_bytes, bool has_finaliser, bool long_lived) {
     size_t n_blocks = ((n_bytes + BYTES_PER_BLOCK - 1) & (~(BYTES_PER_BLOCK - 1))) / BYTES_PER_BLOCK;
     DEBUG_printf("gc_alloc(" UINT_FMT " bytes -> " UINT_FMT " blocks)\n", n_bytes, n_blocks);
 
@@ -424,29 +427,62 @@ void *gc_alloc(size_t n_bytes, bool has_finaliser) {
         return NULL;
     }
 
-    size_t i;
+    size_t found_block = 0xffffffff;
     size_t end_block;
     size_t start_block;
-    size_t n_free = 0;
-    int collected = !MP_STATE_MEM(gc_auto_collect_enabled);
+    size_t n_free;
+    bool collected = !MP_STATE_MEM(gc_auto_collect_enabled);
 
     #if MICROPY_GC_ALLOC_THRESHOLD
     if (!collected && MP_STATE_MEM(gc_alloc_amount) >= MP_STATE_MEM(gc_alloc_threshold)) {
         GC_EXIT();
         gc_collect();
         GC_ENTER();
+        collected = true;
     }
     #endif
 
-    for (;;) {
+    bool keep_looking = true;
 
+    // When we start searching on the other side of the crossover block we make sure to
+    // perform a collect. That way we'll get the closest free block in our section.
+    size_t crossover_block = BLOCK_FROM_PTR(MP_STATE_MEM(gc_lowest_long_lived_ptr));
+    while (keep_looking) {
+        int8_t direction = 1;
+        size_t start = MP_STATE_MEM(gc_first_free_atb_index);
+        if (long_lived) {
+            direction = -1;
+            start = MP_STATE_MEM(gc_last_free_atb_index);
+        }
+        n_free = 0;
         // look for a run of n_blocks available blocks
-        for (i = MP_STATE_MEM(gc_last_free_atb_index); i < MP_STATE_MEM(gc_alloc_table_byte_len); i++) {
+        for (size_t i = start; keep_looking && MP_STATE_MEM(gc_first_free_atb_index) <= i && i <= MP_STATE_MEM(gc_last_free_atb_index); i += direction) {
             byte a = MP_STATE_MEM(gc_alloc_table_start)[i];
-            if (ATB_0_IS_FREE(a)) { if (++n_free >= n_blocks) { i = i * BLOCKS_PER_ATB + 0; goto found; } } else { n_free = 0; }
-            if (ATB_1_IS_FREE(a)) { if (++n_free >= n_blocks) { i = i * BLOCKS_PER_ATB + 1; goto found; } } else { n_free = 0; }
-            if (ATB_2_IS_FREE(a)) { if (++n_free >= n_blocks) { i = i * BLOCKS_PER_ATB + 2; goto found; } } else { n_free = 0; }
-            if (ATB_3_IS_FREE(a)) { if (++n_free >= n_blocks) { i = i * BLOCKS_PER_ATB + 3; goto found; } } else { n_free = 0; }
+            // Four ATB states are packed into a single byte.
+            int j = 0;
+            if (direction == -1) {
+                j = 3;
+            }
+            for (; keep_looking && 0 <= j && j <= 3; j += direction) {
+                if ((a & (0x3 << (j * 2))) == 0) {
+                    if (++n_free >= n_blocks) {
+                        found_block = i * BLOCKS_PER_ATB + j;
+                        keep_looking = false;
+                    }
+                } else {
+                    if (!collected) {
+                        size_t block = i * BLOCKS_PER_ATB + j;
+                        if ((direction == 1 && block >= crossover_block) ||
+                                (direction == -1 && block < crossover_block)) {
+                            keep_looking = false;
+                        }
+                    }
+                    n_free = 0;
+                }
+            }
+        }
+        if (n_free >= n_blocks) {
+            break;
         }
 
         GC_EXIT();
@@ -456,23 +492,31 @@ void *gc_alloc(size_t n_bytes, bool has_finaliser) {
         }
         DEBUG_printf("gc_alloc(" UINT_FMT "): no free mem, triggering GC\n", n_bytes);
         gc_collect();
-        collected = 1;
+        collected = true;
+        // Try again since we've hopefully freed up space.
+        keep_looking = true;
         GC_ENTER();
     }
+    assert(found_block != 0xffffffff);
 
-    // found, ending at block i inclusive
-found:
-    // get starting and end blocks, both inclusive
-    end_block = i;
-    start_block = i - n_free + 1;
-
-    // Set last free ATB index to block after last block we found, for start of
+    // Found free space ending at found_block inclusive.
+    // Also, set last free ATB index to block after last block we found, for start of
     // next scan.  To reduce fragmentation, we only do this if we were looking
     // for a single free block, which guarantees that there are no free blocks
-    // before this one.  Also, whenever we free or shink a block we must check
+    // before this one.  Also, whenever we free or shrink a block we must check
     // if this index needs adjusting (see gc_realloc and gc_free).
-    if (n_free == 1) {
-        MP_STATE_MEM(gc_last_free_atb_index) = (i + 1) / BLOCKS_PER_ATB;
+    if (!long_lived) {
+        end_block = found_block;
+        start_block = found_block - n_free + 1;
+        if (n_blocks == 1) {
+            MP_STATE_MEM(gc_first_free_atb_index) = (found_block + 1) / BLOCKS_PER_ATB;
+        }
+    } else {
+        start_block = found_block;
+        end_block = found_block + n_free - 1;
+        if (n_blocks == 1) {
+            MP_STATE_MEM(gc_last_free_atb_index) = (found_block - 1) / BLOCKS_PER_ATB;
+        }
     }
 
     #ifdef LOG_HEAP_ACTIVITY
@@ -493,6 +537,13 @@ found:
     void *ret_ptr = (void*)(MP_STATE_MEM(gc_pool_start) + start_block * BYTES_PER_BLOCK);
     DEBUG_printf("gc_alloc(%p)\n", ret_ptr);
 
+    // If the allocation was long live then update the lowest value. Its used to trigger early
+    // collects when allocations fail in their respective section. Its also used to ignore calls to
+    // gc_make_long_lived where the pointer is already in the long lived section.
+    if (long_lived && ret_ptr < MP_STATE_MEM(gc_lowest_long_lived_ptr)) {
+        MP_STATE_MEM(gc_lowest_long_lived_ptr) = ret_ptr;
+    }
+
     #if MICROPY_GC_ALLOC_THRESHOLD
     MP_STATE_MEM(gc_alloc_amount) += n_blocks;
     #endif
@@ -566,7 +617,10 @@ void gc_free(void *ptr) {
         #endif
 
         // set the last_free pointer to this block if it's earlier in the heap
-        if (block / BLOCKS_PER_ATB < MP_STATE_MEM(gc_last_free_atb_index)) {
+        if (block / BLOCKS_PER_ATB < MP_STATE_MEM(gc_first_free_atb_index)) {
+            MP_STATE_MEM(gc_first_free_atb_index) = block / BLOCKS_PER_ATB;
+        }
+        if (block / BLOCKS_PER_ATB > MP_STATE_MEM(gc_last_free_atb_index)) {
             MP_STATE_MEM(gc_last_free_atb_index) = block / BLOCKS_PER_ATB;
         }
 
@@ -607,6 +661,50 @@ size_t gc_nbytes(const void *ptr) {
     return 0;
 }
 
+bool gc_has_finaliser(const void *ptr) {
+#if MICROPY_ENABLE_FINALISER
+    GC_ENTER();
+    if (VERIFY_PTR(ptr)) {
+        bool has_finaliser = FTB_GET(BLOCK_FROM_PTR(ptr));
+        GC_EXIT();
+        return has_finaliser;
+    }
+
+    // invalid pointer
+    GC_EXIT();
+#else
+    (void) ptr;
+#endif
+    return false;
+}
+
+void *gc_make_long_lived(void *old_ptr) {
+    // If its already in the long lived section then don't bother moving it.
+    if (old_ptr >= MP_STATE_MEM(gc_lowest_long_lived_ptr)) {
+        return old_ptr;
+    }
+    size_t n_bytes = gc_nbytes(old_ptr);
+    if (n_bytes == 0) {
+        return old_ptr;
+    }
+    bool has_finaliser = gc_has_finaliser(old_ptr);
+
+    // Try and find a new area in the long lived section to copy the memory to.
+    void* new_ptr = gc_alloc(n_bytes, has_finaliser, true);
+    if (new_ptr == NULL) {
+        return old_ptr;
+    } else if (old_ptr > new_ptr) {
+        // Return the old pointer if the new one is lower in the heap and free the new space.
+        gc_free(new_ptr);
+        return old_ptr;
+    }
+    // We copy everything over and let the garbage collection process delete the old copy. That way
+    // we ensure we don't delete memory that has a second reference. (Though if there is we may
+    // confuse things when its mutable.)
+    memcpy(new_ptr, old_ptr, n_bytes);
+    return new_ptr;
+}
+
 #if 0
 // old, simple realloc that didn't expand memory in place
 void *gc_realloc(void *ptr, mp_uint_t n_bytes) {
@@ -639,7 +737,7 @@ void *gc_realloc(void *ptr, mp_uint_t n_bytes) {
 void *gc_realloc(void *ptr_in, size_t n_bytes, bool allow_move) {
     // check for pure allocation
     if (ptr_in == NULL) {
-        return gc_alloc(n_bytes, false);
+        return gc_alloc(n_bytes, false, false);
     }
 
     // check for pure free
@@ -714,7 +812,10 @@ void *gc_realloc(void *ptr_in, size_t n_bytes, bool allow_move) {
         }
 
         // set the last_free pointer to end of this block if it's earlier in the heap
-        if ((block + new_blocks) / BLOCKS_PER_ATB < MP_STATE_MEM(gc_last_free_atb_index)) {
+        if ((block + new_blocks) / BLOCKS_PER_ATB < MP_STATE_MEM(gc_first_free_atb_index)) {
+            MP_STATE_MEM(gc_first_free_atb_index) = (block + new_blocks) / BLOCKS_PER_ATB;
+        }
+        if ((block + new_blocks) / BLOCKS_PER_ATB > MP_STATE_MEM(gc_last_free_atb_index)) {
             MP_STATE_MEM(gc_last_free_atb_index) = (block + new_blocks) / BLOCKS_PER_ATB;
         }
 
@@ -774,7 +875,7 @@ void *gc_realloc(void *ptr_in, size_t n_bytes, bool allow_move) {
     }
 
     // can't resize inplace; try to find a new contiguous chain
-    void *ptr_out = gc_alloc(n_bytes, ftb_state);
+    void *ptr_out = gc_alloc(n_bytes, ftb_state, false);
 
     // check that the alloc succeeded
     if (ptr_out == NULL) {
diff --git a/py/gc.h b/py/gc.h
index 739349c1f5..e5878e1eed 100644
--- a/py/gc.h
+++ b/py/gc.h
@@ -45,9 +45,11 @@ void gc_collect_start(void);
 void gc_collect_root(void **ptrs, size_t len);
 void gc_collect_end(void);
 
-void *gc_alloc(size_t n_bytes, bool has_finaliser);
+void *gc_alloc(size_t n_bytes, bool has_finaliser, bool long_lived);
 void gc_free(void *ptr); // does not call finaliser
 size_t gc_nbytes(const void *ptr);
+bool gc_has_finaliser(const void *ptr);
+void *gc_make_long_lived(void *old_ptr);
 void *gc_realloc(void *ptr, size_t n_bytes, bool allow_move);
 
 typedef struct _gc_info_t {
diff --git a/py/gc_long_lived.c b/py/gc_long_lived.c
new file mode 100644
index 0000000000..c50bbcd836
--- /dev/null
+++ b/py/gc_long_lived.c
@@ -0,0 +1,133 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018 Scott Shawcroft for Adafruit Industries LLC
+ *
+ * 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.
+ */
+
+#include "py/emitglue.h"
+#include "py/gc_long_lived.h"
+#include "py/gc.h"
+
+mp_obj_fun_bc_t *make_fun_bc_long_lived(mp_obj_fun_bc_t *fun_bc, uint8_t max_depth) {
+    #ifndef MICROPY_ENABLE_GC
+    return fun_bc;
+    #endif
+    if (fun_bc == NULL || fun_bc == mp_const_none || max_depth == 0) {
+        return fun_bc;
+    }
+    fun_bc->bytecode = gc_make_long_lived((byte*) fun_bc->bytecode);
+    fun_bc->globals = make_dict_long_lived(fun_bc->globals, max_depth - 1);
+    for (uint32_t i = 0; i < gc_nbytes(fun_bc->const_table) / sizeof(mp_obj_t); i++) {
+        // Skip things that aren't allocated on the heap (and hence have zero bytes.)
+        if (gc_nbytes((byte *)fun_bc->const_table[i]) == 0) {
+            continue;
+        }
+        // Try to detect raw code.
+        mp_raw_code_t* raw_code = MP_OBJ_TO_PTR(fun_bc->const_table[i]);
+        if (raw_code->kind == MP_CODE_BYTECODE) {
+            raw_code->data.u_byte.bytecode = gc_make_long_lived((byte*) raw_code->data.u_byte.bytecode);
+            raw_code->data.u_byte.const_table = gc_make_long_lived((byte*) raw_code->data.u_byte.const_table);
+        }
+        ((mp_uint_t *) fun_bc->const_table)[i] = (mp_uint_t) make_obj_long_lived(
+            (mp_obj_t) fun_bc->const_table[i], max_depth - 1);
+
+    }
+    fun_bc->const_table = gc_make_long_lived((mp_uint_t*) fun_bc->const_table);
+    // extra_args stores keyword only argument default values.
+    size_t words = gc_nbytes(fun_bc) / sizeof(mp_uint_t*);
+    // Functions (mp_obj_fun_bc_t) have four pointers (base, globals, bytecode and const_table)
+    // before the variable length extra_args so remove them from the length.
+    for (size_t i = 0; i < words - 4; i++) {
+        if (fun_bc->extra_args[i] == NULL) {
+            continue;
+        }
+        if (MP_OBJ_IS_TYPE(fun_bc->extra_args[i], &mp_type_dict)) {
+            fun_bc->extra_args[i] = make_dict_long_lived(fun_bc->extra_args[i], max_depth - 1);
+        } else {
+            fun_bc->extra_args[i] = make_obj_long_lived(fun_bc->extra_args[i], max_depth - 1);
+        }
+
+    }
+    return gc_make_long_lived(fun_bc);
+}
+
+mp_obj_property_t *make_property_long_lived(mp_obj_property_t *prop, uint8_t max_depth) {
+    #ifndef MICROPY_ENABLE_GC
+    return prop;
+    #endif
+    if (max_depth == 0) {
+        return prop;
+    }
+    prop->proxy[0] = make_fun_bc_long_lived((mp_obj_fun_bc_t*) prop->proxy[0], max_depth - 1);
+    prop->proxy[1] = make_fun_bc_long_lived((mp_obj_fun_bc_t*) prop->proxy[1], max_depth - 1);
+    prop->proxy[2] = make_fun_bc_long_lived((mp_obj_fun_bc_t*) prop->proxy[2], max_depth - 1);
+    return gc_make_long_lived(prop);
+}
+
+mp_obj_dict_t *make_dict_long_lived(mp_obj_dict_t *dict, uint8_t max_depth) {
+    #ifndef MICROPY_ENABLE_GC
+    return dict;
+    #endif
+    if (dict == NULL || max_depth == 0) {
+        return dict;
+    }
+    // Update all of the references first so that we reduce the chance of references to the old
+    // copies.
+    dict->map.table = gc_make_long_lived(dict->map.table);
+    for (size_t i = 0; i < dict->map.alloc; i++) {
+        if (MP_MAP_SLOT_IS_FILLED(&dict->map, i)) {
+            mp_obj_t value = dict->map.table[i].value;
+            dict->map.table[i].value = make_obj_long_lived(value, max_depth - 1);
+        }
+    }
+    return gc_make_long_lived(dict);
+}
+
+mp_obj_str_t *make_str_long_lived(mp_obj_str_t *str) {
+    str->data = gc_make_long_lived((byte *) str->data);
+    return gc_make_long_lived(str);
+}
+
+mp_obj_t make_obj_long_lived(mp_obj_t obj, uint8_t max_depth){
+    #ifndef MICROPY_ENABLE_GC
+    return obj;
+    #endif
+    if (obj == NULL) {
+        return obj;
+    }
+    if (MP_OBJ_IS_TYPE(obj, &mp_type_fun_bc)) {
+        mp_obj_fun_bc_t *fun_bc = MP_OBJ_TO_PTR(obj);
+        return MP_OBJ_FROM_PTR(make_fun_bc_long_lived(fun_bc, max_depth));
+    } else if (MP_OBJ_IS_TYPE(obj, &mp_type_property)) {
+        mp_obj_property_t *prop = MP_OBJ_TO_PTR(obj);
+        return MP_OBJ_FROM_PTR(make_property_long_lived(prop, max_depth));
+    } else if (MP_OBJ_IS_TYPE(obj, &mp_type_str)) {
+        mp_obj_str_t *str = MP_OBJ_TO_PTR(obj);
+        return MP_OBJ_FROM_PTR(make_str_long_lived(str));
+    } else if (MP_OBJ_IS_TYPE(obj, &mp_type_type)) {
+        // Types are already long lived during creation.
+        return obj;
+    } else {
+        return gc_make_long_lived(obj);
+    }
+}
diff --git a/py/gc_long_lived.h b/py/gc_long_lived.h
new file mode 100644
index 0000000000..229bc73911
--- /dev/null
+++ b/py/gc_long_lived.h
@@ -0,0 +1,43 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018 Scott Shawcroft for Adafruit Industries LLC
+ *
+ * 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.
+ */
+
+// These helpers move MicroPython objects and their sub-objects to the long lived portion of the
+// heap.
+
+#ifndef MICROPY_INCLUDED_PY_GC_LONG_LIVED_H
+#define MICROPY_INCLUDED_PY_GC_LONG_LIVED_H
+
+#include "py/objfun.h"
+#include "py/objproperty.h"
+#include "py/objstr.h"
+
+mp_obj_fun_bc_t *make_fun_bc_long_lived(mp_obj_fun_bc_t *fun_bc, uint8_t max_depth);
+mp_obj_property_t *make_property_long_lived(mp_obj_property_t *prop, uint8_t max_depth);
+mp_obj_dict_t *make_dict_long_lived(mp_obj_dict_t *dict, uint8_t max_depth);
+mp_obj_str_t *make_str_long_lived(mp_obj_str_t *str);
+mp_obj_t make_obj_long_lived(mp_obj_t obj, uint8_t max_depth);
+
+#endif // MICROPY_INCLUDED_PY_GC_LONG_LIVED_H
diff --git a/py/malloc.c b/py/malloc.c
index ea1d4c4b9e..d6983ffdfc 100644
--- a/py/malloc.c
+++ b/py/malloc.c
@@ -53,12 +53,15 @@
 #undef malloc
 #undef free
 #undef realloc
-#define malloc(b) gc_alloc((b), false)
-#define malloc_with_finaliser(b) gc_alloc((b), true)
+#define malloc_ll(b, ll) gc_alloc((b), false, (ll))
+#define malloc_with_finaliser(b) gc_alloc((b), true, false)
 #define free gc_free
 #define realloc(ptr, n) gc_realloc(ptr, n, true)
 #define realloc_ext(ptr, n, mv) gc_realloc(ptr, n, mv)
 #else
+#define malloc_ll(b, ll) malloc(b)
+#define malloc_with_finaliser(b) malloc((b))
+
 STATIC void *realloc_ext(void *ptr, size_t n_bytes, bool allow_move) {
     if (allow_move) {
         return realloc(ptr, n_bytes);
@@ -71,8 +74,8 @@ STATIC void *realloc_ext(void *ptr, size_t n_bytes, bool allow_move) {
 }
 #endif // MICROPY_ENABLE_GC
 
-void *m_malloc(size_t num_bytes) {
-    void *ptr = malloc(num_bytes);
+void *m_malloc(size_t num_bytes, bool long_lived) {
+    void *ptr = malloc_ll(num_bytes, long_lived);
     if (ptr == NULL && num_bytes != 0) {
         m_malloc_fail(num_bytes);
     }
@@ -85,8 +88,8 @@ void *m_malloc(size_t num_bytes) {
     return ptr;
 }
 
-void *m_malloc_maybe(size_t num_bytes) {
-    void *ptr = malloc(num_bytes);
+void *m_malloc_maybe(size_t num_bytes, bool long_lived) {
+    void *ptr = malloc_ll(num_bytes, long_lived);
 #if MICROPY_MEM_STATS
     MP_STATE_MEM(total_bytes_allocated) += num_bytes;
     MP_STATE_MEM(current_bytes_allocated) += num_bytes;
@@ -112,8 +115,8 @@ void *m_malloc_with_finaliser(size_t num_bytes) {
 }
 #endif
 
-void *m_malloc0(size_t num_bytes) {
-    void *ptr = m_malloc(num_bytes);
+void *m_malloc0(size_t num_bytes, bool long_lived) {
+    void *ptr = m_malloc(num_bytes, long_lived);
     if (ptr == NULL && num_bytes != 0) {
         m_malloc_fail(num_bytes);
     }
diff --git a/py/misc.h b/py/misc.h
index 995e4549cd..d9a8efe7f8 100644
--- a/py/misc.h
+++ b/py/misc.h
@@ -56,13 +56,18 @@ typedef unsigned int uint;
 
 // TODO make a lazy m_renew that can increase by a smaller amount than requested (but by at least 1 more element)
 
-#define m_new(type, num) ((type*)(m_malloc(sizeof(type) * (num))))
-#define m_new_maybe(type, num) ((type*)(m_malloc_maybe(sizeof(type) * (num))))
-#define m_new0(type, num) ((type*)(m_malloc0(sizeof(type) * (num))))
+#define m_new(type, num) ((type*)(m_malloc(sizeof(type) * (num), false)))
+#define m_new_ll(type, num) ((type*)(m_malloc(sizeof(type) * (num), true)))
+#define m_new_maybe(type, num) ((type*)(m_malloc_maybe(sizeof(type) * (num), false)))
+#define m_new_ll_maybe(type, num) ((type*)(m_malloc_maybe(sizeof(type) * (num), true)))
+#define m_new0(type, num) ((type*)(m_malloc0(sizeof(type) * (num), false)))
+#define m_new0_ll(type, num) ((type*)(m_malloc0(sizeof(type) * (num), true)))
 #define m_new_obj(type) (m_new(type, 1))
+#define m_new_ll_obj(type) (m_new_ll(type, 1))
 #define m_new_obj_maybe(type) (m_new_maybe(type, 1))
-#define m_new_obj_var(obj_type, var_type, var_num) ((obj_type*)m_malloc(sizeof(obj_type) + sizeof(var_type) * (var_num)))
-#define m_new_obj_var_maybe(obj_type, var_type, var_num) ((obj_type*)m_malloc_maybe(sizeof(obj_type) + sizeof(var_type) * (var_num)))
+#define m_new_obj_var(obj_type, var_type, var_num) ((obj_type*)m_malloc(sizeof(obj_type) + sizeof(var_type) * (var_num), false))
+#define m_new_obj_var_maybe(obj_type, var_type, var_num) ((obj_type*)m_malloc_maybe(sizeof(obj_type) + sizeof(var_type) * (var_num), false))
+#define m_new_ll_obj_var_maybe(obj_type, var_type, var_num) ((obj_type*)m_malloc_maybe(sizeof(obj_type) + sizeof(var_type) * (var_num), true))
 #if MICROPY_ENABLE_FINALISER
 #define m_new_obj_with_finaliser(type) ((type*)(m_malloc_with_finaliser(sizeof(type))))
 #else
@@ -81,10 +86,10 @@ typedef unsigned int uint;
 #endif
 #define m_del_obj(type, ptr) (m_del(type, ptr, 1))
 
-void *m_malloc(size_t num_bytes);
-void *m_malloc_maybe(size_t num_bytes);
+void *m_malloc(size_t num_bytes, bool long_lived);
+void *m_malloc_maybe(size_t num_bytes, bool long_lived);
 void *m_malloc_with_finaliser(size_t num_bytes);
-void *m_malloc0(size_t num_bytes);
+void *m_malloc0(size_t num_bytes, bool long_lived);
 #if MICROPY_MALLOC_USES_ALLOCATED_SIZE
 void *m_realloc(void *ptr, size_t old_num_bytes, size_t new_num_bytes);
 void *m_realloc_maybe(void *ptr, size_t old_num_bytes, size_t new_num_bytes, bool allow_move);
diff --git a/py/modbuiltins.c b/py/modbuiltins.c
index 7283092925..5e11b8d18c 100644
--- a/py/modbuiltins.c
+++ b/py/modbuiltins.c
@@ -79,7 +79,7 @@ STATIC mp_obj_t mp_builtin___build_class__(size_t n_args, const mp_obj_t *args)
     meta_args[2] = class_locals; // dict of members
     mp_obj_t new_class = mp_call_function_n_kw(meta, 3, 0, meta_args);
 
-    // store into cell if neede
+    // store into cell if needed
     if (cell != mp_const_none) {
         mp_obj_cell_set(cell, new_class);
     }
diff --git a/py/mpstate.h b/py/mpstate.h
index 23133cb7e4..19a5d711ed 100644
--- a/py/mpstate.h
+++ b/py/mpstate.h
@@ -76,21 +76,24 @@ typedef struct _mp_state_mem_t {
     byte *gc_pool_start;
     byte *gc_pool_end;
 
+    void *gc_lowest_long_lived_ptr;
+
     int gc_stack_overflow;
     size_t gc_stack[MICROPY_ALLOC_GC_STACK_SIZE];
     size_t *gc_sp;
     uint16_t gc_lock_depth;
 
-    // This variable controls auto garbage collection.  If set to 0 then the
+    // This variable controls auto garbage collection.  If set to false then the
     // GC won't automatically run when gc_alloc can't find enough blocks.  But
     // you can still allocate/free memory and also explicitly call gc_collect.
-    uint16_t gc_auto_collect_enabled;
+    bool gc_auto_collect_enabled;
 
     #if MICROPY_GC_ALLOC_THRESHOLD
     size_t gc_alloc_amount;
     size_t gc_alloc_threshold;
     #endif
 
+    size_t gc_first_free_atb_index;
     size_t gc_last_free_atb_index;
 
     #if MICROPY_PY_GC_COLLECT_RETVAL
diff --git a/py/obj.h b/py/obj.h
index 3f784dafcc..e4d950b97c 100644
--- a/py/obj.h
+++ b/py/obj.h
@@ -816,6 +816,7 @@ typedef struct _mp_obj_module_t {
     mp_obj_dict_t *globals;
 } mp_obj_module_t;
 mp_obj_dict_t *mp_obj_module_get_globals(mp_obj_t self_in);
+void mp_obj_module_set_globals(mp_obj_t self_in, mp_obj_dict_t *globals);
 // check if given module object is a package
 bool mp_obj_is_package(mp_obj_t module);
 
diff --git a/py/objmodule.c b/py/objmodule.c
index 52c6520b9d..86e37850ef 100644
--- a/py/objmodule.c
+++ b/py/objmodule.c
@@ -27,6 +27,7 @@
 #include <stdlib.h>
 #include <assert.h>
 
+#include "py/gc.h"
 #include "py/objmodule.h"
 #include "py/runtime.h"
 #include "py/builtin.h"
@@ -84,8 +85,9 @@ STATIC void module_attr(mp_obj_t self_in, qstr attr, mp_obj_t *dest) {
             mp_obj_dict_delete(MP_OBJ_FROM_PTR(dict), MP_OBJ_NEW_QSTR(attr));
         } else {
             // store attribute
+            mp_obj_t long_lived = gc_make_long_lived(dest[1]);
             // TODO CPython allows STORE_ATTR to a module, but is this the correct implementation?
-            mp_obj_dict_store(MP_OBJ_FROM_PTR(dict), MP_OBJ_NEW_QSTR(attr), dest[1]);
+            mp_obj_dict_store(MP_OBJ_FROM_PTR(dict), MP_OBJ_NEW_QSTR(attr), long_lived);
         }
         dest[0] = MP_OBJ_NULL; // indicate success
     }
@@ -108,9 +110,9 @@ mp_obj_t mp_obj_new_module(qstr module_name) {
     }
 
     // create new module object
-    mp_obj_module_t *o = m_new_obj(mp_obj_module_t);
+    mp_obj_module_t *o = m_new_ll_obj(mp_obj_module_t);
     o->base.type = &mp_type_module;
-    o->globals = MP_OBJ_TO_PTR(mp_obj_new_dict(MICROPY_MODULE_DICT_SIZE));
+    o->globals = MP_OBJ_TO_PTR(gc_make_long_lived(mp_obj_new_dict(MICROPY_MODULE_DICT_SIZE)));
 
     // store __name__ entry in the module
     mp_obj_dict_store(MP_OBJ_FROM_PTR(o->globals), MP_OBJ_NEW_QSTR(MP_QSTR___name__), MP_OBJ_NEW_QSTR(module_name));
@@ -128,6 +130,12 @@ mp_obj_dict_t *mp_obj_module_get_globals(mp_obj_t self_in) {
     return self->globals;
 }
 
+void mp_obj_module_set_globals(mp_obj_t self_in, mp_obj_dict_t *globals) {
+    assert(MP_OBJ_IS_TYPE(self_in, &mp_type_module));
+    mp_obj_module_t *self = MP_OBJ_TO_PTR(self_in);
+    self->globals = globals;
+}
+
 /******************************************************************************/
 // Global module table and related functions
 
diff --git a/py/objtype.c b/py/objtype.c
index 2fefc65ade..1d6dc0b6cd 100644
--- a/py/objtype.c
+++ b/py/objtype.c
@@ -30,6 +30,7 @@
 #include <string.h>
 #include <assert.h>
 
+#include "py/gc_long_lived.h"
 #include "py/objtype.h"
 #include "py/runtime.h"
 
@@ -960,7 +961,7 @@ STATIC void type_attr(mp_obj_t self_in, qstr attr, mp_obj_t *dest) {
                 mp_map_elem_t *elem = mp_map_lookup(locals_map, MP_OBJ_NEW_QSTR(attr), MP_MAP_LOOKUP_ADD_IF_NOT_FOUND);
                 // note that locals_map may be in ROM, so add will fail in that case
                 if (elem != NULL) {
-                    elem->value = dest[1];
+                    elem->value = make_obj_long_lived(dest[1], 10);
                     dest[0] = MP_OBJ_NULL; // indicate success
                 }
             }
@@ -1002,7 +1003,7 @@ mp_obj_t mp_obj_new_type(qstr name, mp_obj_t bases_tuple, mp_obj_t locals_dict)
         }
     }
 
-    mp_obj_type_t *o = m_new0(mp_obj_type_t, 1);
+    mp_obj_type_t *o = m_new0_ll(mp_obj_type_t, 1);
     o->base.type = &mp_type_type;
     o->name = name;
     o->print = instance_print;
@@ -1030,7 +1031,7 @@ mp_obj_t mp_obj_new_type(qstr name, mp_obj_t bases_tuple, mp_obj_t locals_dict)
         }
     }
 
-    o->locals_dict = MP_OBJ_TO_PTR(locals_dict);
+    o->locals_dict = make_dict_long_lived(locals_dict, 10);
 
     const mp_obj_type_t *native_base;
     size_t num_native_bases = instance_count_native_bases(o, &native_base);
diff --git a/py/persistentcode.c b/py/persistentcode.c
index 477ba7501c..ba126a3fb2 100644
--- a/py/persistentcode.c
+++ b/py/persistentcode.c
@@ -124,10 +124,9 @@ STATIC size_t read_uint(mp_reader_t *reader) {
 
 STATIC qstr load_qstr(mp_reader_t *reader) {
     size_t len = read_uint(reader);
-    char *str = m_new(char, len);
+    char str[len];
     read_bytes(reader, (byte*)str, len);
     qstr qst = qstr_from_strn(str, len);
-    m_del(char, str, len);
     return qst;
 }
 
diff --git a/py/py.mk b/py/py.mk
index 9021192df8..21f81c35d5 100644
--- a/py/py.mk
+++ b/py/py.mk
@@ -110,6 +110,7 @@ PY_O_BASENAME = \
 	nlrsetjmp.o \
 	malloc.o \
 	gc.o \
+	gc_long_lived.o \
 	qstr.o \
 	vstr.o \
 	mpprint.o \
diff --git a/py/qstr.c b/py/qstr.c
index 95c9b6835e..49b2d9daaa 100644
--- a/py/qstr.c
+++ b/py/qstr.c
@@ -28,6 +28,7 @@
 #include <string.h>
 #include <stdio.h>
 
+#include "py/gc.h"
 #include "py/mpstate.h"
 #include "py/qstr.h"
 #include "py/gc.h"
@@ -143,7 +144,7 @@ STATIC qstr qstr_add(const byte *q_ptr) {
 
     // make sure we have room in the pool for a new qstr
     if (MP_STATE_VM(last_pool)->len >= MP_STATE_VM(last_pool)->alloc) {
-        qstr_pool_t *pool = m_new_obj_var_maybe(qstr_pool_t, const char*, MP_STATE_VM(last_pool)->alloc * 2);
+        qstr_pool_t *pool = m_new_ll_obj_var_maybe(qstr_pool_t, const char*, MP_STATE_VM(last_pool)->alloc * 2);
         if (pool == NULL) {
             QSTR_EXIT();
             m_malloc_fail(MP_STATE_VM(last_pool)->alloc * 2);
@@ -213,10 +214,10 @@ qstr qstr_from_strn(const char *str, size_t len) {
             if (al < MICROPY_ALLOC_QSTR_CHUNK_INIT) {
                 al = MICROPY_ALLOC_QSTR_CHUNK_INIT;
             }
-            MP_STATE_VM(qstr_last_chunk) = m_new_maybe(byte, al);
+            MP_STATE_VM(qstr_last_chunk) = m_new_ll_maybe(byte, al);
             if (MP_STATE_VM(qstr_last_chunk) == NULL) {
                 // failed to allocate a large chunk so try with exact size
-                MP_STATE_VM(qstr_last_chunk) = m_new_maybe(byte, n_bytes);
+                MP_STATE_VM(qstr_last_chunk) = m_new_ll_maybe(byte, n_bytes);
                 if (MP_STATE_VM(qstr_last_chunk) == NULL) {
                     QSTR_EXIT();
                     m_malloc_fail(n_bytes);
@@ -258,7 +259,7 @@ qstr qstr_build_end(byte *q_ptr) {
         mp_uint_t hash = qstr_compute_hash(Q_GET_DATA(q_ptr), len);
         Q_SET_HASH(q_ptr, hash);
         q_ptr[MICROPY_QSTR_BYTES_IN_HASH + MICROPY_QSTR_BYTES_IN_LEN + len] = '\0';
-        q = qstr_add(q_ptr);
+        q = qstr_add(gc_make_long_lived(q_ptr));
     } else {
         m_del(byte, q_ptr, Q_GET_ALLOC(q_ptr));
     }
diff --git a/tools/analyze_heap_dump.py b/tools/analyze_heap_dump.py
index 31b66b9dfc..d5da884e48 100644
--- a/tools/analyze_heap_dump.py
+++ b/tools/analyze_heap_dump.py
@@ -9,6 +9,10 @@ import sys
 import pygraphviz as pgv
 import io
 import html
+import os.path
+import string
+
+import click
 
 from analyze_mpy import Prelude
 
@@ -32,176 +36,211 @@ READLINE_HIST_SIZE = 8
 
 SKIP_SYMBOLS = [".debug_ranges", ".debug_frame", ".debug_loc", ".comment", ".debug_str", ".debug_line", ".debug_abbrev", ".debug_info", "COMMON"]
 
-ownership_graph = pgv.AGraph(directed=True)
+@click.command()
+@click.argument("ram_filename")
+@click.argument("bin_filename")
+@click.argument("map_filename")
+@click.option("--print_block_contents", default=False,
+              help="Prints the contents of each allocated block")
+@click.option("--print_unknown_types", default=False,
+              help="Prints the micropython base type if we don't understand it.")
+@click.option("--print_block_state", default=False,
+              help="Prints the heap block states (allocated or free)")
+@click.option("--print_conflicting_symbols", default=False,
+              help="Prints conflicting symbols from the map")
+@click.option("--print-heap-structure/--no-print-heap-structure", default=False,
+              help="Print heap structure")
+@click.option("--output_directory", default="heapvis",
+              help="Destination for rendered output")
+@click.option("--draw-heap-layout/--no-draw-heap-layout", default=True,
+              help="Draw the heap layout")
+@click.option("--draw-heap-ownership/--no-draw-heap-ownership", default=False,
+              help="Draw the ownership graph of blocks on the heap")
+@click.option("--draw-heap-ownership/--no-draw-heap-ownership", default=False,
+              help="Draw the ownership graph of blocks on the heap")
+@click.option("--analyze-snapshots", default="last", type=click.Choice(['all', 'last']))
+def do_all_the_things(ram_filename, bin_filename, map_filename, print_block_contents,
+                      print_unknown_types, print_block_state, print_conflicting_symbols,
+                      print_heap_structure, output_directory, draw_heap_layout,
+                      draw_heap_ownership, analyze_snapshots):
+    with open(ram_filename, "rb") as f:
+        ram_dump = f.read()
 
-with open(sys.argv[1], "rb") as f:
-    ram = f.read()
+    with open(bin_filename, "rb") as f:
+        rom = f.read()
 
-with open(sys.argv[2], "rb") as f:
-    rom = f.read()
+    symbols = {} # name -> address, size
+    symbol_lookup = {} # address -> name
+    manual_symbol_map = {} # autoname -> name
 
-symbols = {} # name -> address, size
-symbol_lookup = {} # address -> name
-manual_symbol_map = {} # autoname -> name
+    def add_symbol(name, address=None, size=None):
+        if "lto_priv" in name:
+            name = name.split(".")[0]
+        if address:
+            address = int(address, 0)
+        if size:
+            size = int(size, 0)
+        if name in symbols:
+            if address and symbols[name][0] and symbols[name][0] != address:
+                if print_conflicting_symbols:
+                    print("Conflicting symbol: {} at addresses 0x{:08x} and 0x{:08x}".format(name, address, symbols[name][0]))
+                return
+            if not address:
+                address = symbols[name][0]
+            if not size:
+                size = symbols[name][1]
+        symbols[name] = (address, size)
+        if address:
+            if not size:
+                size = 4
+            for offset in range(0, size, 4):
+                symbol_lookup[address + offset] = "{}+{}".format(name, offset)
 
-def add_symbol(name, address=None, size=None):
-    global symbols
-    if address:
-        address = int(address, 0)
-    if size:
-        size = int(size, 0)
-    if name in symbols:
-        if address and symbols[name][0] and symbols[name][0] != address:
-            print("Conflicting symbol: {}".format(name))
-            return
-        if not address:
-            address = symbols[name][0]
-        if not size:
-            size = symbols[name][1]
-    symbols[name] = (address, size)
-    if address:
-        if not size:
-            size = 4
-        for offset in range(0, size, 4):
-            symbol_lookup[address + offset] = "{}+{}".format(name, offset)
+    with open(map_filename, "r") as f:
+        common_symbols = False
+        name = None
+        for line in f:
+            line = line.strip()
+            parts = line.split()
+            if line.startswith("Common symbol"):
+                common_symbols = True
+            if line == "Discarded input sections":
+                common_symbols = False
+            if common_symbols:
+                if len(parts) == 1:
+                    name = parts[0]
+                elif len(parts) == 2 and name:
+                    add_symbol(name, size=parts[0])
+                    name = None
+                elif len(parts) == 3:
+                    add_symbol(parts[0], size=parts[1])
+                    name = None
+            else:
+                if len(parts) == 1 and parts[0].startswith((".text", ".rodata", ".bss")) and parts[0].count(".") > 1 and not parts[0].isnumeric() and ".str" not in parts[0]:
+                    name = parts[0].split(".")[2]
+                if len(parts) == 3 and parts[0].startswith("0x") and parts[1].startswith("0x") and name:
+                    add_symbol(name, parts[0], parts[1])
+                    name = None
+                if len(parts) == 2 and parts[0].startswith("0x") and not parts[1].startswith("0x"):
+                    add_symbol(parts[1], parts[0])
+                if len(parts) == 4 and parts[0] not in SKIP_SYMBOLS and parts[1].startswith("0x") and parts[2].startswith("0x"):
+                    name, address, size, source = parts
+                    if name.startswith((".text", ".rodata", ".bss")) and name.count(".") > 1:
+                        name = name.split(".")[-1]
+                        add_symbol(name, address, size)
+                    name = None
+                # Linker symbols
+                if len(parts) >= 4 and parts[0].startswith("0x") and parts[2] == "=" and parts[1] != ".":
+                    add_symbol(parts[1], parts[0])
 
-with open(sys.argv[3], "r") as f:
-    common_symbols = False
-    name = None
-    for line in f:
-        line = line.strip()
-        parts = line.split()
-        if line.startswith("Common symbol"):
-            common_symbols = True
-        if line == "Discarded input sections":
-            common_symbols = False
-        if common_symbols:
-            if len(parts) == 1:
-                name = parts[0]
-            elif len(parts) == 2 and name:
-                add_symbol(name, size=parts[0])
-                name = None
-            elif len(parts) == 3:
-                add_symbol(parts[0], size=parts[1])
-                name = None
-        else:
-            if len(parts) == 2 and parts[0].startswith("0x") and not parts[1].startswith("0x"):
-                add_symbol(parts[1], parts[0])
-            if len(parts) == 4 and parts[0] not in SKIP_SYMBOLS and parts[1].startswith("0x") and parts[2].startswith("0x"):
-                name, address, size, source = parts
-                if name.startswith((".text", ".rodata", ".bss")) and name.count(".") > 1:
-                    name = name.split(".")[-1]
-                    add_symbol(name, address, size)
-            # Linker symbols
-            if len(parts) >= 4 and parts[0].startswith("0x") and parts[2] == "=" and parts[1] != ".":
-                add_symbol(parts[1], parts[0])
+    rom_start = symbols["_sfixed"][0]
+    ram_start = symbols["_srelocate"][0]
+    ram_end = symbols["_estack"][0]
+    ram_length = ram_end - ram_start
+    if analyze_snapshots == "all":
+        snapshots = range(len(ram_dump) // ram_length - 1, -1, -1)
+    elif analyze_snapshots == "last":
+        snapshots = range(len(ram_dump) // ram_length - 1, len(ram_dump) // ram_length - 2, -1)
+    for snapshot_num in snapshots:
+        ram = ram_dump[ram_length*snapshot_num:ram_length*(snapshot_num + 1)]
 
-rom_start = symbols["_sfixed"][0]
-ram_start = symbols["_srelocate"][0]
+        ownership_graph = pgv.AGraph(directed=True)
+        def load(address, size=4):
+            if size is None:
+                raise ValueError("You must provide a size")
+            if address > ram_start:
+                ram_address = address - ram_start
+                if (ram_address + size) > len(ram):
+                    raise ValueError("Unable to read 0x{:08x} from ram.".format(address))
+                return ram[ram_address:ram_address+size]
+            elif address < len(rom):
+                if (address + size) > len(rom):
+                    raise ValueError("Unable to read 0x{:08x} from rom.".format(address))
+                return rom[address:address+size]
 
-def load(address, size=4):
-    if size is None:
-        raise ValueError("You must provide a size")
-    if address > ram_start:
-        ram_address = address - ram_start
-        if (ram_address + size) > len(ram):
-            raise ValueError("Unable to read 0x{:08x} from ram.".format(address))
-        return ram[ram_address:ram_address+size]
-    elif address < len(rom):
-        if (address + size) > len(rom):
-            raise ValueError("Unable to read 0x{:08x} from rom.".format(address))
-        return rom[address:address+size]
+        def load_pointer(address):
+            return struct.unpack("<I", load(address))[0]
 
-def load_pointer(address):
-    return struct.unpack("<I", load(address))[0]
+        heap_start, heap_size = symbols["heap"]
+        heap = load(heap_start, heap_size)
+        total_byte_len = len(heap)
 
-heap_start, heap_size = symbols["heap"]
-heap = load(heap_start, heap_size)
-total_byte_len = len(heap)
+        # These change every run so we load them from the symbol table
+        mp_state_ctx = symbols["mp_state_ctx"][0]
+        manual_symbol_map["mp_state_ctx+20"] = "mp_state_ctx.vm.last_pool"
+        last_pool = load_pointer(mp_state_ctx + 20) # (gdb) p &mp_state_ctx.vm.last_pool
+        manual_symbol_map["mp_state_ctx+88"] = "mp_state_ctx.vm.dict_main.map.table"
+        dict_main_table = load_pointer(mp_state_ctx + 88) # (gdb) p &mp_state_ctx.vm.dict_main.map.table
+        manual_symbol_map["mp_state_ctx+68"] = "mp_state_ctx.vm.mp_loaded_modules_dict.map.table"
+        imports_table = load_pointer(mp_state_ctx + 68) # (gdb) p &mp_state_ctx.vm.mp_loaded_modules_dict.map.table
 
-# These change every run so we load them from the symbol table
-mp_state_ctx = symbols["mp_state_ctx"][0]
-manual_symbol_map["mp_state_ctx+24"] = "mp_state_ctx.vm.last_pool"
-last_pool = load_pointer(mp_state_ctx + 24) # (gdb) p &mp_state_ctx.vm.last_pool
-manual_symbol_map["mp_state_ctx+92"] = "mp_state_ctx.vm.dict_main.map.table"
-dict_main_table = load_pointer(mp_state_ctx + 92) # (gdb) p &mp_state_ctx.vm.dict_main.map.table
-manual_symbol_map["mp_state_ctx+72"] = "mp_state_ctx.vm.mp_loaded_modules_dict.map.table"
-imports_table = load_pointer(mp_state_ctx + 72) # (gdb) p &mp_state_ctx.vm.mp_loaded_modules_dict.map.table
+        manual_symbol_map["mp_state_ctx+104"] = "mp_state_ctx.vm.mp_sys_path_obj.items"
+        manual_symbol_map["mp_state_ctx+120"] = "mp_state_ctx.vm.mp_sys_argv_obj.items"
 
-manual_symbol_map["mp_state_ctx+108"] = "mp_state_ctx.vm.mp_sys_path_obj.items"
-manual_symbol_map["mp_state_ctx+124"] = "mp_state_ctx.vm.mp_sys_argv_obj.items"
+        for i in range(READLINE_HIST_SIZE):
+            manual_symbol_map["mp_state_ctx+{}".format(128 + i * 4)] = "mp_state_ctx.vm.readline_hist[{}]".format(i)
 
-for i in range(READLINE_HIST_SIZE):
-    manual_symbol_map["mp_state_ctx+{}".format(128 + i * 4)] = "mp_state_ctx.vm.readline_hist[{}]".format(i)
+        tuple_type = symbols["mp_type_tuple"][0]
+        type_type = symbols["mp_type_type"][0]
+        map_type = symbols["mp_type_map"][0]
+        dict_type = symbols["mp_type_dict"][0]
+        property_type = symbols["mp_type_property"][0]
+        str_type = symbols["mp_type_str"][0]
+        function_types = [symbols["mp_type_fun_" + x][0] for x in ["bc", "builtin_0", "builtin_1", "builtin_2", "builtin_3", "builtin_var"]]
+        bytearray_type = symbols["mp_type_bytearray"][0]
 
-tuple_type = symbols["mp_type_tuple"][0]
-type_type = symbols["mp_type_type"][0]
-map_type = symbols["mp_type_map"][0]
-dict_type = symbols["mp_type_dict"][0]
-property_type = symbols["mp_type_property"][0]
-str_type = symbols["mp_type_str"][0]
-function_types = [symbols["mp_type_fun_" + x][0] for x in ["bc", "builtin_0", "builtin_1", "builtin_2", "builtin_3", "builtin_var"]]
-bytearray_type = symbols["mp_type_bytearray"][0]
+        dynamic_type = 0x40000000 # placeholder, doesn't match any memory
 
-dynamic_type = 0x40000000 # placeholder, doesn't match any memory
+        type_colors = {
+            dict_type: "red",
+            property_type: "yellow",
+            map_type: "blue",
+            type_type: "orange",
+            tuple_type: "skyblue",
+            str_type: "pink",
+            bytearray_type: "purple"
+            }
 
-type_colors = {
-    dict_type: "red",
-    property_type: "yellow",
-    map_type: "blue",
-    type_type: "orange",
-    tuple_type: "skyblue",
-    str_type: "pink",
-    bytearray_type: "purple"
-    }
+        pool_shift = heap_start % BYTES_PER_BLOCK
+        atb_length = total_byte_len * BITS_PER_BYTE // (BITS_PER_BYTE + BITS_PER_BYTE * BLOCKS_PER_ATB // BLOCKS_PER_FTB + BITS_PER_BYTE * BLOCKS_PER_ATB * BYTES_PER_BLOCK)
+        pool_length = atb_length * BLOCKS_PER_ATB * BYTES_PER_BLOCK
+        gc_finaliser_table_byte_len = (atb_length * BLOCKS_PER_ATB + BLOCKS_PER_FTB - 1) // BLOCKS_PER_FTB
 
-pool_shift = heap_start % BYTES_PER_BLOCK
+        if print_heap_structure:
+            print("mp_state_ctx at 0x{:08x} and length {}".format(*symbols["mp_state_ctx"]))
+            print("Total heap length:", total_byte_len)
+            print("ATB length:", atb_length)
+            print("Total allocatable:", pool_length)
+            print("FTB length:", gc_finaliser_table_byte_len)
 
-print("Total heap length:", total_byte_len)
-atb_length = total_byte_len * BITS_PER_BYTE // (BITS_PER_BYTE + BITS_PER_BYTE * BLOCKS_PER_ATB // BLOCKS_PER_FTB + BITS_PER_BYTE * BLOCKS_PER_ATB * BYTES_PER_BLOCK)
+        pool_start = heap_start + total_byte_len - pool_length - pool_shift
+        pool = heap[-pool_length-pool_shift:]
 
-print("ATB length:", atb_length)
-pool_length = atb_length * BLOCKS_PER_ATB * BYTES_PER_BLOCK
-print("Total allocatable:", pool_length)
+        total_height = 65 * 18
+        total_width = (pool_length // (64 * 16)) * 90
 
-gc_finaliser_table_byte_len = (atb_length * BLOCKS_PER_ATB + BLOCKS_PER_FTB - 1) // BLOCKS_PER_FTB
-print("FTB length:", gc_finaliser_table_byte_len)
+        map_element_blocks = [dict_main_table, imports_table]
+        string_blocks = []
+        bytecode_blocks = []
+        qstr_pools = []
+        qstr_chunks = []
+        block_data = {}
 
-pool_start = heap_start + total_byte_len - pool_length - pool_shift
-pool = heap[-pool_length-pool_shift:]
+        # Find all the qtr pool addresses.
+        prev_pool = last_pool
+        while prev_pool > ram_start:
+            qstr_pools.append(prev_pool)
+            prev_pool = load_pointer(prev_pool)
 
-map_element_blocks = [dict_main_table, imports_table]
-string_blocks = []
-bytecode_blocks = []
-qstr_pools = []
-qstr_chunks = []
-block_data = {}
-
-# Find all the qtr pool addresses.
-prev_pool = last_pool
-while prev_pool > ram_start:
-    qstr_pools.append(prev_pool)
-    prev_pool = load_pointer(prev_pool)
-
-longest_free = 0
-current_free = 0
-current_allocation = 0
-total_free = 0
-for i in range(atb_length):
-    # Each atb byte is four blocks worth of info
-    atb = heap[i]
-    for j in range(4):
-        block_state = (atb >> (j * 2)) & 0x3
-        if block_state != AT_FREE and current_free > 0:
-            print("{} bytes free".format(current_free * BYTES_PER_BLOCK))
-            current_free = 0
-        if block_state != AT_TAIL and current_allocation > 0:
+        def save_allocated_block(end, current_allocation):
             allocation_length = current_allocation * BYTES_PER_BLOCK
-            end = (i * BLOCKS_PER_ATB + j) * BYTES_PER_BLOCK
             start = end - allocation_length
             address = pool_start + start
             data = pool[start:end]
-            print("0x{:x} {} bytes allocated".format(address, allocation_length))
+            if print_block_state:
+                print("0x{:x} {} bytes allocated".format(address, allocation_length))
+            if print_block_contents:
+                print(data)
 
             rows = ""
             for k in range(current_allocation - 1):
@@ -214,6 +253,7 @@ for i in range(atb_length):
             ownership_graph.add_node(address, label=table, style="invisible", shape="plaintext")
             potential_type = None
             node = ownership_graph.get_node(address)
+            node.attr["height"] = 0.25 * current_allocation
             block_data[address] = data
             for k in range(len(data) // 4):
                 word = struct.unpack_from("<I", data, offset=(k * 4))[0]
@@ -226,9 +266,8 @@ for i in range(atb_length):
                         bgcolor = "green"
                     elif potential_type in type_colors:
                         bgcolor = type_colors[potential_type]
-                    else:
-                        pass
-                        #print("unknown type", hex(potential_type))
+                    elif print_unknown_types:
+                        print("unknown type", hex(potential_type))
                     node.attr["label"] = "<" + node.attr["label"].replace("\"gray\"", "\"" + bgcolor + "\"") + ">"
 
                 if potential_type == str_type and k == 3:
@@ -262,180 +301,294 @@ for i in range(atb_length):
                     if k == 2 and 0x20000000 < word < 0x20040000:
                         bytecode_blocks.append(word)
 
-            current_allocation = 0
-        if block_state == AT_FREE:
-            current_free += 1
-            total_free += 1
-        elif block_state == AT_HEAD:
-            current_allocation = 1
-        elif block_state == AT_TAIL:
-            current_allocation += 1
-        longest_free = max(longest_free, current_free)
-if current_free > 0:
-    print("{} bytes free".format(current_free * BYTES_PER_BLOCK))
 
-def is_qstr(obj):
-    return obj & 0xff800007 == 0x00000006
+        longest_free = 0
+        current_free = 0
+        current_allocation = 0
+        total_free = 0
+        for i in range(atb_length):
+            # Each atb byte is four blocks worth of info
+            atb = heap[i]
+            for j in range(4):
+                block_state = (atb >> (j * 2)) & 0x3
+                if block_state != AT_FREE and current_free > 0:
+                    if print_block_state:
+                        print("{} bytes free".format(current_free * BYTES_PER_BLOCK))
+                    current_free = 0
+                if block_state != AT_TAIL and current_allocation > 0:
+                    save_allocated_block((i * BLOCKS_PER_ATB + j) * BYTES_PER_BLOCK, current_allocation)
+                    current_allocation = 0
+                if block_state == AT_FREE:
+                    current_free += 1
+                    total_free += 1
+                elif block_state == AT_HEAD or block_state == AT_MARK:
+                    current_allocation = 1
+                elif block_state == AT_TAIL and current_allocation > 0:
+                    # In gc_free the logging happens before the tail is freed. So checking
+                    # current_allocation > 0 ensures we only extend an allocation thats started.
+                    current_allocation += 1
+                longest_free = max(longest_free, current_free)
+        #if current_free > 0:
+        #    print("{} bytes free".format(current_free * BYTES_PER_BLOCK))
+        if current_allocation > 0:
+            save_allocated_block(pool_length, current_allocation)
 
-def find_qstr(qstr_index):
-    pool_ptr = last_pool
-    if not is_qstr(qstr_index):
-        return "object"
-    qstr_index >>= 3
-    while pool_ptr != 0:
-        #print(hex(pool_ptr))
-        if pool_ptr in block_data:
-            pool = block_data[pool_ptr]
-            prev, total_prev_len, alloc, length = struct.unpack_from("<IIII", pool)
-        else:
-            rom_offset = pool_ptr - rom_start
-            prev, total_prev_len, alloc, length = struct.unpack_from("<IIII", rom[rom_offset:rom_offset+32])
-            pool = rom[rom_offset:rom_offset+length*4]
-            #print("rom pool")
-        #print(hex(prev), total_prev_len, alloc, length)
-        #print(qstr_index, total_prev_len)
-        if qstr_index >= total_prev_len:
-            offset = (qstr_index - total_prev_len) * 4 + 16
-            start = struct.unpack_from("<I", pool, offset=offset)[0]
-            #print(hex(start))
-            if start < heap_start:
-                start -= rom_start
-                if start > len(rom):
-                    return "more than rom: {:x}".format(start + rom_start)
-                qstr_hash, qstr_len = struct.unpack("<BB", rom[start:start+2])
-                return rom[start+2:start+2+qstr_len].decode("utf-8")
+        def is_qstr(obj):
+            return obj & 0xff800007 == 0x00000006
+
+        def find_qstr(qstr_index):
+            pool_ptr = last_pool
+            if not is_qstr(qstr_index):
+                return "object"
+            qstr_index >>= 3
+            while pool_ptr != 0:
+                if pool_ptr > ram_start:
+                    if pool_ptr in block_data:
+                        pool = block_data[pool_ptr]
+                        prev, total_prev_len, alloc, length = struct.unpack_from("<IIII", pool)
+                    else:
+                        print("missing qstr pool: {:08x}".format(pool_ptr))
+                        return "missing"
+                else:
+                    rom_offset = pool_ptr - rom_start
+                    prev, total_prev_len, alloc, length = struct.unpack_from("<IIII", rom[rom_offset:rom_offset+32])
+                    pool = rom[rom_offset:rom_offset+length*4]
+
+                if qstr_index >= total_prev_len:
+                    offset = (qstr_index - total_prev_len) * 4 + 16
+                    start = struct.unpack_from("<I", pool, offset=offset)[0]
+                    if start < heap_start:
+                        start -= rom_start
+                        if start > len(rom):
+                            return "more than rom: {:x}".format(start + rom_start)
+                        qstr_hash, qstr_len = struct.unpack("<BB", rom[start:start+2])
+                        return rom[start+2:start+2+qstr_len].decode("utf-8")
+                    else:
+                        if start > heap_start + len(heap):
+                            return "out of range: {:x}".format(start)
+                        local = start - heap_start
+                        qstr_hash, qstr_len = struct.unpack("<BB", heap[local:local+2])
+                        return heap[local+2:local+2+qstr_len].decode("utf-8")
+
+                pool_ptr = prev
+            return "unknown"
+
+        def format(obj):
+            if obj & 1 != 0:
+                return obj >> 1
+            if is_qstr(obj):
+                return find_qstr(obj)
             else:
-                if start > heap_start + len(heap):
-                    return "out of range: {:x}".format(start)
-                local = start - heap_start
-                qstr_hash, qstr_len = struct.unpack("<BB", heap[local:local+2])
-                return heap[local+2:local+2+qstr_len].decode("utf-8")
+                return "0x{:08x}".format(obj)
 
-        pool_ptr = prev
-    return "unknown"
+        for block in sorted(map_element_blocks):
+            if block == 0:
+                continue
+            try:
+                node = ownership_graph.get_node(block)
+            except KeyError:
+                print("Unable to find memory block for 0x{:08x}. Is there something running?".format(block))
+                continue
+            if block not in block_data:
+                continue
+            data = block_data[block]
+            cells = []
+            for i in range(len(data) // 8):
+                key, value = struct.unpack_from("<II", data, offset=(i * 8))
+                if key == MP_OBJ_NULL or key == MP_OBJ_SENTINEL:
+                    cells.append(("", " "))
+                else:
+                    cells.append((key, format(key)))
+                    if value in block_data:
+                        edge = ownership_graph.get_edge(block, value)
+                        edge.attr["tailport"] = str(key)
+            rows = ""
+            for i in range(len(cells) // 2):
+                rows += "<tr><td port=\"{}\">{}</td><td port=\"{}\">{}</td></tr>".format(
+                    cells[2*i][0],
+                    cells[2*i][1],
+                    cells[2*i+1][0],
+                    cells[2*i+1][1])
+            node.attr["shape"] = "plaintext"
+            node.attr["style"] = "invisible"
+            node.attr["label"] = "<<table bgcolor=\"gold\" border=\"1\" cellpadding=\"0\" cellspacing=\"0\"><tr><td colspan=\"2\">0x{:08x}</td></tr>{}</table>>".format(block, rows)
 
-def format(obj):
-    if obj & 1 != 0:
-        return obj >> 1
-    if is_qstr(obj):
-        return find_qstr(obj)
-    else:
-        return "0x{:08x}".format(obj)
+        for node, degree in ownership_graph.in_degree_iter():
+            if degree == 0:
+                address_bytes = struct.pack("<I", int(node))
+                location = -1
+                for _ in range(ram.count(address_bytes)):
+                    location = ram.find(address_bytes, location + 1)
+                    pointer_location = ram_start + location
+                    source = "0x{:08x}".format(pointer_location)
+                    if pointer_location in symbol_lookup:
+                        source = symbol_lookup[pointer_location]
+                    if source in manual_symbol_map:
+                        source = manual_symbol_map[source]
+                    if "readline_hist" in source:
+                        string_blocks.append(int(node))
+                    ownership_graph.add_edge(source, node)
 
-for block in sorted(map_element_blocks):
-    try:
-        node = ownership_graph.get_node(block)
-    except KeyError:
-        print("Unable to find memory block for 0x{:08x}. Is there something running?".format(block))
-        continue
-    #node.attr["fillcolor"] = "gold"
-    data = block_data[block]
-    #print("0x{:08x}".format(block))
-    cells = []
-    for i in range(len(data) // 8):
-        key, value = struct.unpack_from("<II", data, offset=(i * 8))
-        if key == MP_OBJ_NULL or key == MP_OBJ_SENTINEL:
-            #print("  <empty slot>")
-            cells.append(("", " "))
-        else:
-            #print("  {}, {}".format(format(key), format(value)))
-            cells.append((key, format(key)))
-            if value in block_data:
-                edge = ownership_graph.get_edge(block, value)
-                edge.attr["tailport"] = str(key)
-    rows = ""
-    for i in range(len(cells) // 2):
-        rows += "<tr><td port=\"{}\">{}</td><td port=\"{}\">{}</td></tr>".format(
-            cells[2*i][0],
-            cells[2*i][1],
-            cells[2*i+1][0],
-            cells[2*i+1][1])
-    node.attr["shape"] = "plaintext"
-    node.attr["style"] = "invisible"
-    node.attr["label"] = "<<table bgcolor=\"gold\" border=\"1\" cellpadding=\"0\" cellspacing=\"0\"><tr><td colspan=\"2\">0x{:08x}</td></tr>{}</table>>".format(block, rows)
+        for block in string_blocks:
+            if block == 0:
+                continue
+            node = ownership_graph.get_node(block)
+            node.attr["fillcolor"] = "hotpink"
+            if block in block_data:
+                raw_string = block_data[block]
+            else:
+                print("Unable to find memory block for string at 0x{:08x}.".format(block))
+                continue
+            try:
+                raw_string = block_data[block].decode('utf-8')
+            except:
+                raw_string = str(block_data[block])
+            wrapped = []
+            for i in range(0, len(raw_string), 16):
+                wrapped.append(raw_string[i:i+16])
+            node.attr["label"] = "\n".join(wrapped)
+            node.attr["style"] = "filled"
+            node.attr["fontname"] = "FiraCode-Medium"
+            node.attr["fontpath"] = "/Users/tannewt/Library/Fonts/"
+            node.attr["fontsize"] = 8
+            node.attr["height"] = len(wrapped) * 0.25
 
-for node, degree in ownership_graph.in_degree_iter():
-    if degree == 0:
-        address_bytes = struct.pack("<I", int(node))
-        location = -1
-        for _ in range(ram.count(address_bytes)):
-            location = ram.find(address_bytes, location + 1)
-            pointer_location = ram_start + location
-            source = "0x{:08x}".format(pointer_location)
-            if pointer_location in symbol_lookup:
-                source = symbol_lookup[pointer_location]
-            if source in manual_symbol_map:
-                source = manual_symbol_map[source]
-            if "readline_hist" in source:
-                string_blocks.append(int(node))
-            ownership_graph.add_edge(source, node)
+        for block in bytecode_blocks:
+            node = ownership_graph.get_node(block)
+            node.attr["fillcolor"] = "lightseagreen"
+            if block in block_data:
+                data = block_data[block]
+            else:
+                print("Unable to find memory block for bytecode at 0x{:08x}.".format(block))
+                continue
+            prelude = Prelude(io.BufferedReader(io.BytesIO(data)))
+            node.attr["shape"] = "plaintext"
+            node.attr["style"] = "invisible"
+            code_info_size = prelude.code_info_size
+            rows = ""
+            remaining_bytecode = len(data) - 16
+            while code_info_size >= 16:
+                rows += "<tr><td colspan=\"16\" bgcolor=\"palegreen\" height=\"18\" width=\"80\"></td></tr>"
+                code_info_size -= 16
+                remaining_bytecode -= 16
+            if code_info_size > 0:
+                rows += ("<tr><td colspan=\"{}\" bgcolor=\"palegreen\" height=\"18\" width=\"{}\"></td>"
+                         "<td colspan=\"{}\" bgcolor=\"seagreen\" height=\"18\" width=\"{}\"></td></tr>"
+                        ).format(code_info_size, code_info_size * (80 / 16), (16 - code_info_size), (80 / 16) * (16 - code_info_size))
+                remaining_bytecode -= 16
+            for i in range(remaining_bytecode // 16):
+                rows += "<tr><td colspan=\"16\" bgcolor=\"seagreen\" height=\"18\" width=\"80\"></td></tr>"
+            node.attr["label"] = "<<table border=\"1\" cellspacing=\"0\"><tr><td colspan=\"16\" bgcolor=\"lightseagreen\" height=\"18\" width=\"80\">0x{:08x}</td></tr>{}</table>>".format(block, rows)
 
-for block in string_blocks:
-    node = ownership_graph.get_node(block)
-    node.attr["fillcolor"] = "hotpink"
-    string = block_data[block].decode('utf-8')
-    wrapped = []
-    for i in range(0, len(string), 16):
-        wrapped.append(string[i:i+16])
-    node.attr["label"] = "\n".join(wrapped)
-    node.attr["style"] = "filled"
-    node.attr["fontname"] = "FiraCode-Medium"
-    node.attr["fontpath"] = "/Users/tannewt/Library/Fonts/"
-    node.attr["fontsize"] = 8
+        for block in qstr_chunks:
+            if block not in block_data:
+                ownership_graph.delete_node(block)
+                continue
+            data = block_data[block]
+            qstrs_in_chunk = ""
+            offset = 0
+            while offset < len(data) - 1:
+                qstr_hash, qstr_len = struct.unpack_from("<BB", data, offset=offset)
+                if qstr_hash == 0:
+                    qstrs_in_chunk += " " * (len(data) - offset)
+                    offset = len(data)
+                    continue
+                offset += 2 + qstr_len + 1
+                qstrs_in_chunk += "  " + data[offset - qstr_len - 1: offset - 1].decode("utf-8")
+            printable_qstrs = ""
+            for i in range(len(qstrs_in_chunk)):
+                c = qstrs_in_chunk[i]
+                if c not in string.printable or c in "\v\f":
+                    printable_qstrs += "░"
+                else:
+                    printable_qstrs += qstrs_in_chunk[i]
+            wrapped = []
+            for i in range(0, len(printable_qstrs), 16):
+                wrapped.append(html.escape(printable_qstrs[i:i+16]))
+            node = ownership_graph.get_node(block)
+            node.attr["label"] = "<<table border=\"1\" cellspacing=\"0\" bgcolor=\"lightsalmon\" width=\"80\"><tr><td height=\"18\" >0x{:08x}</td></tr><tr><td height=\"{}\" >{}</td></tr></table>>".format(block, 18 * (len(wrapped) - 1), "<br/>".join(wrapped))
+            node.attr["fontname"] = "FiraCode-Medium"
+            node.attr["fontpath"] = "/Users/tannewt/Library/Fonts/"
+            node.attr["fontsize"] = 8
 
-for block in bytecode_blocks:
-    node = ownership_graph.get_node(block)
-    node.attr["fillcolor"] = "lightseagreen"
-    data = block_data[block]
-    prelude = Prelude(io.BufferedReader(io.BytesIO(data)))
-    node.attr["shape"] = "plaintext"
-    node.attr["style"] = "invisible"
-    code_info_size = prelude.code_info_size
-    rows = ""
-    remaining_bytecode = len(data) - 16
-    while code_info_size >= 16:
-        rows += "<tr><td colspan=\"16\" bgcolor=\"palegreen\" height=\"18\" width=\"80\"></td></tr>"
-        code_info_size -= 16
-        remaining_bytecode -= 16
-    if code_info_size > 0:
-        rows += ("<tr><td colspan=\"{}\" bgcolor=\"palegreen\" height=\"18\" width=\"{}\"></td>"
-                 "<td colspan=\"{}\" bgcolor=\"seagreen\" height=\"18\" width=\"{}\"></td></tr>"
-                ).format(code_info_size, code_info_size * (80 / 16), (16 - code_info_size), (80 / 16) * (16 - code_info_size))
-        remaining_bytecode -= 16
-    for i in range(remaining_bytecode // 16):
-        rows += "<tr><td colspan=\"16\" bgcolor=\"seagreen\" height=\"18\" width=\"80\"></td></tr>"
-    node.attr["label"] = "<<table border=\"1\" cellspacing=\"0\"><tr><td colspan=\"16\" bgcolor=\"lightseagreen\" height=\"18\" width=\"80\">0x{:08x}</td></tr>{}</table>>".format(block, rows)
+        print("Total free space:", BYTES_PER_BLOCK * total_free)
+        print("Longest free space:", BYTES_PER_BLOCK * longest_free)
 
-for block in qstr_chunks:
-    if block not in block_data:
-        ownership_graph.delete_node(block)
-        continue
-    data = block_data[block]
-    string = ""
-    offset = 0
-    while offset < len(data) - 1:
-        qstr_hash, qstr_len = struct.unpack_from("<BB", data, offset=offset)
-        if qstr_hash == 0:
-            string += " " * (len(data) - offset)
-            offset = len(data)
-            continue
-        offset += 2 + qstr_len + 1
-        string += "  " + data[offset - qstr_len - 1: offset - 1].decode("utf-8")
-    #print(string)
-    wrapped = []
-    for i in range(0, len(string), 16):
-        wrapped.append(html.escape(string[i:i+16]))
-    node = ownership_graph.get_node(block)
-    node.attr["label"] = "<<table border=\"1\" cellspacing=\"0\" bgcolor=\"lightsalmon\" width=\"80\"><tr><td height=\"18\" >0x{:08x}</td></tr><tr><td height=\"{}\" >{}</td></tr></table>>".format(block, 18 * (len(wrapped) - 1), "<br/>".join(wrapped))
-    node.attr["fontname"] = "FiraCode-Medium"
-    node.attr["fontpath"] = "/Users/tannewt/Library/Fonts/"
-    node.attr["fontsize"] = 8
+        # First render the graph of objects on the heap.
+        if draw_heap_ownership:
+            ownership_graph.layout(prog="dot")
+            fn = os.path.join(output_directory, "heap_ownership{:04d}.png".format(snapshot_num))
+            print(fn)
+            ownership_graph.draw(fn)
 
-print("Total free space:", BYTES_PER_BLOCK * total_free)
-print("Longest free space:", BYTES_PER_BLOCK * longest_free)
+        # Second, render the heap layout in memory order.
+        for node in ownership_graph:
+            try:
+                address = int(node.name)
+            except ValueError:
+                ownership_graph.remove_node(node)
+                continue
+            block = (address - pool_start) // 16
+            x = block // 64
+            y = 64 - block % 64
+            try:
+                height = float(node.attr["height"])
+            except:
+                height = 0.25
+            #print(hex(address), "height", height, y)
+            #if address in block_data:
+            #    print(hex(address), block, len(block_data[address]), x, y, height)
+            node.attr["pos"] = "{},{}".format(x * 80, (y - (height - 0.25) * 2) * 18) # in inches
 
-with open("heap.dot", "w") as f:
-    f.write(ownership_graph.string())
+        # Clear edge positioning from ownership graph layout.
+        if draw_heap_ownership:
+            for edge in ownership_graph.iteredges():
+                del edge.attr["pos"]
 
-ownership_graph.layout(prog="dot")
-ownership_graph.draw("heap.png")
+        # Reformat block nodes so they are the correct size and do not have keys in them.
+        for block in sorted(map_element_blocks):
+            try:
+                node = ownership_graph.get_node(block)
+            except KeyError:
+                if block != 0:
+                    print("Unable to find memory block for 0x{:08x}. Is there something running?".format(block))
+                continue
+            #node.attr["fillcolor"] = "gold"
+            if block not in block_data:
+                continue
+            data = block_data[block]
+            #print("0x{:08x}".format(block))
+            cells = []
+            for i in range(len(data) // 8):
+                key, value = struct.unpack_from("<II", data, offset=(i * 8))
+                if key == MP_OBJ_NULL or key == MP_OBJ_SENTINEL:
+                    #print("  <empty slot>")
+                    cells.append(("", " "))
+                else:
+                    #print("  {}, {}".format(format(key), format(value)))
+                    cells.append((key, ""))
+                    if value in block_data:
+                        edge = ownership_graph.get_edge(block, value)
+                        edge.attr["tailport"] = str(key)
+            rows = ""
+            for i in range(len(cells) // 2):
+                rows += "<tr><td port=\"{}\" height=\"18\" width=\"40\">{}</td><td port=\"{}\" height=\"18\" width=\"40\">{}</td></tr>".format(
+                    cells[2*i][0],
+                    cells[2*i][1],
+                    cells[2*i+1][0],
+                    cells[2*i+1][1])
+            node.attr["label"] = "<<table bgcolor=\"gold\" border=\"1\" cellpadding=\"0\" cellspacing=\"0\">{}</table>>".format(rows)
+
+
+        ownership_graph.add_node("center", pos="{},{}".format(total_width // 2 - 40, total_height // 2), shape="plaintext", label=" ")
+        ownership_graph.graph_attr["viewport"] = "{},{},1,{}".format(total_width, total_height, "center")
+
+        ownership_graph.has_layout = True
+
+        if draw_heap_layout:
+            fn = os.path.join(output_directory, "heap_layout{:04d}.png".format(snapshot_num))
+            print(fn)
+            ownership_graph.draw(fn)
+
+if __name__ == "__main__":
+    do_all_the_things()
diff --git a/tools/analyze_mpy.py b/tools/analyze_mpy.py
index 00be661065..376207a24e 100644
--- a/tools/analyze_mpy.py
+++ b/tools/analyze_mpy.py
@@ -13,46 +13,79 @@ bytecode_format_sizes = {
 }
 
 bytecodes = {
+    0x00: {"name": "MP_BC_LOAD_FAST_MULTI",
+           "format": "MP_OPCODE_BYTE"},
     0x10: {"name": "MP_BC_LOAD_CONST_FALSE",
            "format": "MP_OPCODE_BYTE"},
-#define MP_BC_LOAD_CONST_NONE    (0x11)
-#define MP_BC_LOAD_CONST_TRUE    (0x12)
-#define MP_BC_LOAD_CONST_SMALL_INT   (0x14) // signed var-int
-#define MP_BC_LOAD_CONST_STRING  (0x16) // qstr
+    0x11: {"name": "MP_BC_LOAD_CONST_NONE",
+           "format": "MP_OPCODE_BYTE"},
+    0x12: {"name": "MP_BC_LOAD_CONST_TRUE",
+           "format": "MP_OPCODE_BYTE"},
+    0x14: {"name": "MP_BC_LOAD_CONST_SMALL_INT",
+           "format": "MP_OPCODE_VAR_UINT"},
+    0x16: {"name": "MP_BC_LOAD_CONST_STRING",
+           "format": "MP_OPCODE_QSTR"},
+    0x17: {"name": "MP_BC_LOAD_CONST_OBJ",
+           "format": "MP_OPCODE_VAR_UINT"},
 #define MP_BC_LOAD_CONST_OBJ     (0x17) // ptr
-#define MP_BC_LOAD_NULL          (0x18)
+    0x18: {"name": "MP_BC_LOAD_NULL",
+           "format": "MP_OPCODE_BYTE"},
 
 #define MP_BC_LOAD_FAST_N        (0x19) // uint
-#define MP_BC_LOAD_DEREF         (0x1a) // uint
-#define MP_BC_LOAD_NAME          (0x1b) // qstr
-#define MP_BC_LOAD_GLOBAL        (0x1c) // qstr
-#define MP_BC_LOAD_ATTR          (0x1d) // qstr
-#define MP_BC_LOAD_METHOD        (0x1e) // qstr
-#define MP_BC_LOAD_SUPER_METHOD  (0x1f) // qstr
+    0x1a: {"name": "MP_BC_LOAD_DEREF",
+           "format": "MP_OPCODE_VAR_UINT"},
+    0x1b: {"name": "MP_BC_LOAD_NAME",
+           "format": "MP_OPCODE_QSTR"},
+    0x1c: {"name": "MP_BC_LOAD_GLOBAL",
+           "format": "MP_OPCODE_QSTR"},
+    0x1d: {"name": "MP_BC_LOAD_ATTR",
+           "format": "MP_OPCODE_QSTR"},
+    0x1e: {"name": "MP_BC_LOAD_METHOD",
+           "format": "MP_OPCODE_QSTR"},
+    0x1f: {"name": "MP_BC_LOAD_SUPER_METHOD",
+           "format": "MP_OPCODE_QSTR"},
+    0x20: {"name": "MP_BC_LOAD_BUILD_CLASS",
+           "format": "MP_OPCODE_BYTE"},
 #define MP_BC_LOAD_BUILD_CLASS   (0x20)
 #define MP_BC_LOAD_SUBSCR        (0x21)
+    0x21: {"name": "MP_BC_LOAD_SUBSCR",
+           "format": "MP_OPCODE_BYTE"},
 
 #define MP_BC_STORE_FAST_N       (0x22) // uint
 #define MP_BC_STORE_DEREF        (0x23) // uint
 #define MP_BC_STORE_NAME         (0x24) // qstr
-#define MP_BC_STORE_GLOBAL       (0x25) // qstr
-#define MP_BC_STORE_ATTR         (0x26) // qstr
-#define MP_BC_STORE_SUBSCR       (0x27)
+    0x24: {"name": "MP_BC_STORE_NAME",
+           "format": "MP_OPCODE_QSTR"},
+    0x25: {"name": "MP_BC_STORE_GLOBAL",
+           "format": "MP_OPCODE_QSTR"},
+    0x26: {"name": "MP_BC_STORE_ATTR",
+           "format": "MP_OPCODE_QSTR"},
+    0x27: {"name": "MP_BC_LOAD_SUBSCR",
+           "format": "MP_OPCODE_BYTE"},
 
+    0x28: {"name": "MP_BC_DELETE_FAST",
+           "format": "MP_OPCODE_VAR_UINT"},
 #define MP_BC_DELETE_FAST        (0x28) // uint
 #define MP_BC_DELETE_DEREF       (0x29) // uint
 #define MP_BC_DELETE_NAME        (0x2a) // qstr
 #define MP_BC_DELETE_GLOBAL      (0x2b) // qstr
 
-#define MP_BC_DUP_TOP            (0x30)
+    0x30: {"name": "MP_BC_DUP_TOP",
+           "format": "MP_OPCODE_BYTE"},
 #define MP_BC_DUP_TOP_TWO        (0x31)
-#define MP_BC_POP_TOP            (0x32)
-#define MP_BC_ROT_TWO            (0x33)
-#define MP_BC_ROT_THREE          (0x34)
+    0x32: {"name": "MP_BC_POP_TOP",
+           "format": "MP_OPCODE_BYTE"},
+    0x33: {"name": "MP_BC_ROT_TWO",
+           "format": "MP_OPCODE_BYTE"},
+    0x34: {"name": "MP_BC_ROT_THREE",
+           "format": "MP_OPCODE_BYTE"},
 
-#define MP_BC_JUMP               (0x35) // rel byte code offset, 16-bit signed, in excess
-#define MP_BC_POP_JUMP_IF_TRUE   (0x36) // rel byte code offset, 16-bit signed, in excess
-#define MP_BC_POP_JUMP_IF_FALSE  (0x37) // rel byte code offset, 16-bit signed, in excess
+    0x35: {"name": "MP_BC_JUMP",
+           "format": "MP_OPCODE_OFFSET"},
+    0x36: {"name": "MP_BC_POP_JUMP_IF_TRUE",
+           "format": "MP_OPCODE_OFFSET"},
+    0x37: {"name": "MP_BC_POP_JUMP_IF_FALSE",
+           "format": "MP_OPCODE_OFFSET"},
 #define MP_BC_JUMP_IF_TRUE_OR_POP    (0x38) // rel byte code offset, 16-bit signed, in excess
 #define MP_BC_JUMP_IF_FALSE_OR_POP   (0x39) // rel byte code offset, 16-bit signed, in excess
 #define MP_BC_SETUP_WITH         (0x3d) // rel byte code offset, 16-bit unsigned
@@ -62,44 +95,172 @@ bytecodes = {
 #define MP_BC_END_FINALLY        (0x41)
 #define MP_BC_GET_ITER           (0x42)
 #define MP_BC_FOR_ITER           (0x43) // rel byte code offset, 16-bit unsigned
-#define MP_BC_POP_BLOCK          (0x44)
+    0x43: {"name": "MP_BC_FOR_ITER",
+           "format": "MP_OPCODE_OFFSET"},
+
+    0x44: {"name": "MP_BC_POP_BLOCK",
+           "format": "MP_OPCODE_BYTE"},
 #define MP_BC_POP_EXCEPT         (0x45)
 #define MP_BC_UNWIND_JUMP        (0x46) // rel byte code offset, 16-bit signed, in excess; then a byte
-#define MP_BC_GET_ITER_STACK     (0x47)
+    0x47: {"name": "MP_BC_GET_ITER_STACK",
+           "format": "MP_OPCODE_BYTE"},
 
-#define MP_BC_BUILD_TUPLE        (0x50) // uint
-#define MP_BC_BUILD_LIST         (0x51) // uint
-#define MP_BC_BUILD_MAP          (0x53) // uint
-#define MP_BC_STORE_MAP          (0x54)
+
+    0x50: {"name": "MP_BC_BUILD_TUPLE",
+           "format": "MP_OPCODE_VAR_UINT"},
+    0x51: {"name": "MP_BC_BUILD_LIST",
+           "format": "MP_OPCODE_VAR_UINT"},
+    0x53: {"name": "MP_BC_BUILD_MAP",
+           "format": "MP_OPCODE_VAR_UINT"},
+    0x54: {"name": "MP_BC_STORE_MAP",
+           "format": "MP_OPCODE_BYTE"},
 #define MP_BC_BUILD_SET          (0x56) // uint
 #define MP_BC_BUILD_SLICE        (0x58) // uint
 #define MP_BC_STORE_COMP         (0x57) // uint
+    0x57: {"name": "MP_BC_STORE_COMP",
+           "format": "MP_OPCODE_VAR_UINT"},
 #define MP_BC_UNPACK_SEQUENCE    (0x59) // uint
 #define MP_BC_UNPACK_EX          (0x5a) // uint
 
-#define MP_BC_RETURN_VALUE       (0x5b)
-#define MP_BC_RAISE_VARARGS      (0x5c) // byte
+    0x5b: {"name": "MP_BC_RETURN_VALUE",
+           "format": "MP_OPCODE_BYTE"},
+    0x5c: {"name": "MP_BC_RAISE_VARARGS",
+           "format": "MP_OPCODE_BYTE_EXTRA"},
 #define MP_BC_YIELD_VALUE        (0x5d)
 #define MP_BC_YIELD_FROM         (0x5e)
 
 #define MP_BC_MAKE_FUNCTION         (0x60) // uint
-#define MP_BC_MAKE_FUNCTION_DEFARGS (0x61) // uint
-#define MP_BC_MAKE_CLOSURE          (0x62) // uint
-#define MP_BC_MAKE_CLOSURE_DEFARGS  (0x63) // uint
-#define MP_BC_CALL_FUNCTION         (0x64) // uint
-#define MP_BC_CALL_FUNCTION_VAR_KW  (0x65) // uint
-#define MP_BC_CALL_METHOD           (0x66) // uint
-#define MP_BC_CALL_METHOD_VAR_KW    (0x67) // uint
+    0x60: {"name": "MP_BC_MAKE_FUNCTION",
+           "format": "MP_OPCODE_VAR_UINT"},
+    0x61: {"name": "MP_BC_MAKE_FUNCTION_DEFARGS",
+           "format": "MP_OPCODE_VAR_UINT"},
+    0x62: {"name": "MP_BC_MAKE_CLOSURE",
+           "format": "MP_OPCODE_VAR_UINT_EXTRA"},
+    0x63: {"name": "MP_BC_MAKE_CLOSURE",
+           "format": "MP_OPCODE_VAR_UINT_EXTRA"},
+    0x64: {"name": "MP_BC_CALL_FUNCTION",
+           "format": "MP_OPCODE_VAR_UINT"},
+    0x65: {"name": "MP_BC_CALL_FUNCTION_VAR_KW",
+           "format": "MP_OPCODE_VAR_UINT"},
+    0x66: {"name": "MP_BC_CALL_METHOD",
+           "format": "MP_OPCODE_VAR_UINT"},
+    0x67: {"name": "MP_BC_CALL_METHOD_VAR_KW",
+           "format": "MP_OPCODE_VAR_UINT"},
 
-#define MP_BC_IMPORT_NAME        (0x68) // qstr
+    0x68: {"name": "MP_BC_IMPORT_NAME",
+           "format": "MP_OPCODE_QSTR"},
+    0x69: {"name": "MP_BC_IMPORT_FROM",
+           "format": "MP_OPCODE_QSTR"},
 #define MP_BC_IMPORT_FROM        (0x69) // qstr
 #define MP_BC_IMPORT_STAR        (0x6a)
 
 #define MP_BC_LOAD_CONST_SMALL_INT_MULTI (0x70) // + N(64)
+    0x7f: {"name": "MP_BC_LOAD_CONST_SMALL_INT_MULTI -1",
+           "format": "MP_OPCODE_BYTE"},
+    0x80: {"name": "MP_BC_LOAD_CONST_SMALL_INT_MULTI 0",
+           "format": "MP_OPCODE_BYTE"},
+    0x81: {"name": "MP_BC_LOAD_CONST_SMALL_INT_MULTI 1",
+           "format": "MP_OPCODE_BYTE"},
+    0x82: {"name": "MP_BC_LOAD_CONST_SMALL_INT_MULTI 2",
+           "format": "MP_OPCODE_BYTE"},
+    0x83: {"name": "MP_BC_LOAD_CONST_SMALL_INT_MULTI 3",
+           "format": "MP_OPCODE_BYTE"},
+    0x84: {"name": "MP_BC_LOAD_CONST_SMALL_INT_MULTI 4",
+           "format": "MP_OPCODE_BYTE"},
 #define MP_BC_LOAD_FAST_MULTI            (0xb0) // + N(16)
+    0xb0: {"name": "MP_BC_LOAD_FAST_MULTI 0",
+           "format": "MP_OPCODE_BYTE"},
+    0xb1: {"name": "MP_BC_LOAD_FAST_MULTI 1",
+           "format": "MP_OPCODE_BYTE"},
+    0xb2: {"name": "MP_BC_LOAD_FAST_MULTI 2",
+           "format": "MP_OPCODE_BYTE"},
+    0xb3: {"name": "MP_BC_LOAD_FAST_MULTI 3",
+           "format": "MP_OPCODE_BYTE"},
+    0xb4: {"name": "MP_BC_LOAD_FAST_MULTI 4",
+           "format": "MP_OPCODE_BYTE"},
+    0xb5: {"name": "MP_BC_LOAD_FAST_MULTI 5",
+           "format": "MP_OPCODE_BYTE"},
+    0xb6: {"name": "MP_BC_LOAD_FAST_MULTI 6",
+           "format": "MP_OPCODE_BYTE"},
+    0xb7: {"name": "MP_BC_LOAD_FAST_MULTI 7",
+           "format": "MP_OPCODE_BYTE"},
+    0xb8: {"name": "MP_BC_LOAD_FAST_MULTI 8",
+           "format": "MP_OPCODE_BYTE"},
 #define MP_BC_STORE_FAST_MULTI           (0xc0) // + N(16)
+    0xc0: {"name": "MP_BC_STORE_FAST_MULTI 0",
+           "format": "MP_OPCODE_BYTE"},
+    0xc1: {"name": "MP_BC_STORE_FAST_MULTI 1",
+           "format": "MP_OPCODE_BYTE"},
+    0xc2: {"name": "MP_BC_STORE_FAST_MULTI 2",
+           "format": "MP_OPCODE_BYTE"},
+    0xc3: {"name": "MP_BC_STORE_FAST_MULTI 3",
+           "format": "MP_OPCODE_BYTE"},
+    0xc4: {"name": "MP_BC_STORE_FAST_MULTI 4",
+           "format": "MP_OPCODE_BYTE"},
+    0xc5: {"name": "MP_BC_STORE_FAST_MULTI 5",
+           "format": "MP_OPCODE_BYTE"},
+    0xc6: {"name": "MP_BC_STORE_FAST_MULTI 6",
+           "format": "MP_OPCODE_BYTE"},
+    0xc7: {"name": "MP_BC_STORE_FAST_MULTI 7",
+           "format": "MP_OPCODE_BYTE"},
 #define MP_BC_UNARY_OP_MULTI             (0xd0) // + op(<MP_UNARY_OP_NUM_BYTECODE)
+
+    # // 9 relational operations, should return a bool
+    0xd7: {"name": "MP_BC_BINARY_OP_MULTI MP_BINARY_OP_LESS",
+           "format": "MP_OPCODE_BYTE"},
+    0xd8: {"name": "MP_BC_BINARY_OP_MULTI MP_BINARY_OP_MORE",
+           "format": "MP_OPCODE_BYTE"},
+    0xd9: {"name": "MP_BC_BINARY_OP_MULTI MP_BINARY_OP_EQUAL",
+           "format": "MP_OPCODE_BYTE"},
+    0xda: {"name": "MP_BC_BINARY_OP_MULTI MP_BINARY_OP_LESS_EQUAL",
+           "format": "MP_OPCODE_BYTE"},
+    0xdb: {"name": "MP_BC_BINARY_OP_MULTI MP_BINARY_OP_MORE_EQUAL",
+           "format": "MP_OPCODE_BYTE"},
+    0xdc: {"name": "MP_BC_BINARY_OP_MULTI MP_BINARY_OP_NOT_EQUAL",
+           "format": "MP_OPCODE_BYTE"},
+    # dc: MP_BINARY_OP_NOT_EQUAL,
+    # dd: MP_BINARY_OP_IN,
+    # de: MP_BINARY_OP_IS,
+    # df: MP_BINARY_OP_EXCEPTION_MATCH,
+    #
+    # // 12 inplace arithmetic operations
+    # e0: MP_BINARY_OP_INPLACE_OR,
+    # e1: MP_BINARY_OP_INPLACE_XOR,
+    # e2: MP_BINARY_OP_INPLACE_AND,
+    # e3: MP_BINARY_OP_INPLACE_LSHIFT,
+    # e4: MP_BINARY_OP_INPLACE_RSHIFT,
+    # e5: MP_BINARY_OP_INPLACE_ADD,
+    0xe5: {"name": "MP_BC_BINARY_OP_MULTI MP_BINARY_OP_INPLACE_ADD",
+           "format": "MP_OPCODE_BYTE"},
+    0xe6: {"name": "MP_BC_BINARY_OP_MULTI MP_BINARY_OP_INPLACE_SUBTRACT",
+           "format": "MP_OPCODE_BYTE"},
+    # e7: MP_BINARY_OP_INPLACE_MULTIPLY,
+    # e8: MP_BINARY_OP_INPLACE_FLOOR_DIVIDE,
+    # e9: MP_BINARY_OP_INPLACE_TRUE_DIVIDE,
+    # ea: MP_BINARY_OP_INPLACE_MODULO,
+    # eb: MP_BINARY_OP_INPLACE_POWER,
+    #
+    # // 12 normal arithmetic operations
+    # ec: MP_BINARY_OP_OR,
+    # ed: MP_BINARY_OP_XOR,
+    # ee: MP_BINARY_OP_AND,
+    # ef: MP_BINARY_OP_LSHIFT,
+    # f0: MP_BINARY_OP_RSHIFT,
 #define MP_BC_BINARY_OP_MULTI            (0xd7) // + op(<MP_BINARY_OP_NUM_BYTECODE)
+    0xf1: {"name": "MP_BC_BINARY_OP_MULTI MP_BINARY_OP_ADD",
+           "format": "MP_OPCODE_BYTE"},
+    0xf2: {"name": "MP_BC_BINARY_OP_MULTI MP_BINARY_OP_SUBTRACT",
+           "format": "MP_OPCODE_BYTE"},
+    0xf3: {"name": "MP_BC_BINARY_OP_MULTI MP_BINARY_OP_MULTIPLY",
+           "format": "MP_OPCODE_BYTE"},
+    0xf4: {"name": "MP_BC_BINARY_OP_MULTI MP_BINARY_OP_FLOOR_DIVIDE",
+           "format": "MP_OPCODE_BYTE"},
+    0xf5: {"name": "MP_BC_BINARY_OP_MULTI MP_BINARY_OP_TRUE_DIVIDE",
+           "format": "MP_OPCODE_BYTE"},
+    0xf6: {"name": "MP_BC_BINARY_OP_MULTI MP_BINARY_OP_MODULO",
+           "format": "MP_OPCODE_BYTE"},
+    0xf7: {"name": "MP_BC_BINARY_OP_MULTI MP_BINARY_OP_POWER",
+           "format": "MP_OPCODE_BYTE"},
 }
 
 def read_uint(encoded_uint, peek=False):
@@ -149,40 +310,94 @@ class RawCode:
     def __init__(self, encoded_raw_code):
         bc_len = read_uint(encoded_raw_code)
         bc = encoded_raw_code.read(bc_len)
-        prelude = Prelude(io.BufferedReader(io.BytesIO(bc)))
-        encoded_code_info = bc[:prelude.code_info_size]
-        bc_start = prelude.code_info_size
-        while bc[bc_start] == 0xff:
-            bc_start += 1
-        bc = bc[bc_start:]
+        bc = io.BufferedReader(io.BytesIO(bc))
+        prelude = Prelude(bc)
+        encoded_code_info = bc.read(prelude.code_info_size)
+        bc.read(1)
+        while bc.peek(1)[0] == 0xff:
+            bc.read(1)
+        bc = bytearray(bc.read())
+        #print(encoded_code_info, bc)
 
         self.qstrs = []
 
         self.simple_name = self._load_qstr(encoded_raw_code)
         self.source_file = self._load_qstr(encoded_raw_code)
         # the simple name and source file qstr indexes get written back into the byte code somehow
+        #print(bc)
         self._load_bytecode_qstrs(encoded_raw_code, bc)
+
+        #print(encoded_raw_code.peek(20)[:20])
+
+        n_obj = read_uint(encoded_raw_code)
+        n_raw_code = read_uint(encoded_raw_code)
+
+        self.const_table = []
+        for i in range(prelude.n_pos_args + prelude.n_kwonly_args):
+            self.const_table.append(self._load_qstr(encoded_raw_code))
+            print("load args", self.const_table[-1])
+        for i in range(n_obj):
+            self.const_table.append(self._load_obj(encoded_raw_code))
+            print("load obj", self.const_table[-1])
+        for i in range(n_raw_code):
+            print("load raw code")
+            self.const_table.append(RawCode(encoded_raw_code))
+
         print(self.qstrs[self.simple_name], self.qstrs[self.source_file])
-        print(binascii.hexlify(encoded_raw_code.peek(20)[:20]))
+        #print(binascii.hexlify(encoded_raw_code.peek(20)[:20]))
 
     def _load_qstr(self, encoded_qstr):
         string_len = read_uint(encoded_qstr)
         string = encoded_qstr.read(string_len).decode("utf-8")
+        print(string)
         if string in self.qstrs:
-            return self.qstr.index(string)
+            return self.qstrs.index(string)
         new_index = len(self.qstrs)
         self.qstrs.append(string)
         return new_index
 
-    def _load_bytecode_qstrs(encoded_raw_code, bytecode):
+    def _load_obj(self, encoded_obj):
+        obj_type = encoded_obj.read(1)
+        if obj_type == b'e':
+            return "..."
+        else:
+            str_len = read_uint(encoded_obj)
+            s = encoded_obj.read(str_len)
+            if obj_type == b's':
+                return s.decode("utf-8")
+            elif obj_type == b'b':
+                return s
+            elif obj_type == b'i':
+                return int(s)
+            elif obj_type == b'f':
+                return float(s)
+            elif obj_type == b'c':
+                return float(s)
+        raise RuntimeError("Unknown object type {}".format(obj_type))
+
+    def _load_bytecode_qstrs(self, encoded_raw_code, bytecode):
         i = 0
         while i < len(bytecode):
-            opcode, opcode_size = mp_opcode_format(bytecode[i])
-            if opcode == MP_OPCODE_QSTR:
+            bc = bytecode[i]
+            if bc not in bytecodes:
+                raise RuntimeError("missing code 0x{:x} at {}".format(bc, i))
+                return
+            bc = bytecodes[bc]
+            opcode = bc["name"]
+            print(opcode)
+            opcode_size = bytecode_format_sizes[bc["format"]]
+            if bc["format"] == "MP_OPCODE_QSTR":
                 qstr_index = self._load_qstr(encoded_raw_code)
                 bytecode[i+1] = qstr_index
                 bytecode[i+2] = qstr_index >> 8
-            opcode += opcode_size
+            if not opcode_size:
+                i += 2
+                while (bytecode[i] & 0x80) != 0:
+                    i += 1
+                if bc["format"] == "MP_OPCODE_VAR_UINT_EXTRA":
+                    i += 1
+            else:
+                i += opcode_size
 
 class mpyFile:
     def __init__(self, encoded_mpy):
diff --git a/tools/gc_activity.md b/tools/gc_activity.md
index 40252bdf73..d1a4c28031 100644
--- a/tools/gc_activity.md
+++ b/tools/gc_activity.md
@@ -13,7 +13,7 @@ correct port. GDB is usually :3333 and JLink is :2331.
 Now, run gdb from your port directory:
 
 ```
-arm-none-eabi-gdb -x ../tools/output_gc_until_repl.txt build-metro_m0_flash/firmware.elf
+arm-none-eabi-gdb -x ../tools/output_gc_until_repl.txt build-metro_m0_express/firmware.elf
 ```
 
 This will take a little time while it breaks, backtraces and continues for every
diff --git a/tools/output_gc_until_repl.txt b/tools/output_gc_until_repl.txt
index 28fb292198..0e99626353 100644
--- a/tools/output_gc_until_repl.txt
+++ b/tools/output_gc_until_repl.txt
@@ -10,15 +10,16 @@ set logging on
 set remote hardware-breakpoint-limit 4
 
 # gc log
-break gc.c:110
+break gc.c:103
 commands
 backtrace
 p/x start_block
 p/x length
+append binary memory ram.bin &_srelocate &_estack
 continue
 end
 
-break mp_hal_stdin_rx_chr
+break main.c:164
 
 continue