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authorKartik K. Agaram <vc@akkartik.com>2016-01-26 23:47:23 -0800
committerKartik K. Agaram <vc@akkartik.com>2016-01-26 23:47:23 -0800
commitd009e158803956c76adbf8f58a62884c3e7affb3 (patch)
treeb88198e28d15cd1fc064f5300365a190decc4c50 /html/038new.cc.html
parent2da43c9462c7b7c1bb78d2f2826b3b97b4874973 (diff)
downloadmu-d009e158803956c76adbf8f58a62884c3e7affb3.tar.gz
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+<title>Mu - 038new.cc</title>
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+<pre id='vimCodeElement'>
+<span class="Comment">//: Creating space for new variables at runtime.</span>
+
+<span class="Comment">//: Mu has two primitives for managing allocations:</span>
+<span class="Comment">//: - 'allocate' reserves a specified amount of space</span>
+<span class="Comment">//: - 'abandon' returns allocated space to be reused by future calls to 'allocate'</span>
+<span class="Comment">//:</span>
+<span class="Comment">//: In practice it's useful to let programs copy addresses anywhere they want,</span>
+<span class="Comment">//: but a prime source of (particularly security) bugs is accessing memory</span>
+<span class="Comment">//: after it's been abandoned. To avoid this, mu programs use a safer</span>
+<span class="Comment">//: primitive called 'new', which adds two features:</span>
+<span class="Comment">//:</span>
+<span class="Comment">//: - it takes a type rather than a size, to save you the trouble of</span>
+<span class="Comment">//: calculating sizes of different variables.</span>
+<span class="Comment">//: - it allocates an extra location where it tracks so-called 'reference</span>
+<span class="Comment">//: counts' or refcounts: the number of address variables in your program that</span>
+<span class="Comment">//: point to this allocation. The initial refcount of an allocation starts out</span>
+<span class="Comment">//: at 1 (the product of the 'new' instruction). When other variables are</span>
+<span class="Comment">//: copied from it the refcount is incremented. When a variable stops pointing</span>
+<span class="Comment">//: at it the refcount is decremented. When the refcount goes to 0 the</span>
+<span class="Comment">//: allocation is automatically abandoned.</span>
+<span class="Comment">//:</span>
+<span class="Comment">//: Mu programs guarantee you'll have no memory corruption bugs as long as you</span>
+<span class="Comment">//: use 'new' and never use 'allocate' or 'abandon'. However, they don't help</span>
+<span class="Comment">//: you at all to remember to abandon memory after you're done with it. To</span>
+<span class="Comment">//: minimize memory use, be sure to reset allocated addresses to 0 when you're</span>
+<span class="Comment">//: done with them.</span>
+
+<span class="Comment">//: To help you distinguish addresses that point at allocations, 'new' returns</span>
+<span class="Comment">//: type address:shared:___. Think of 'shared' as a generic container that</span>
+<span class="Comment">//: contains one extra field: the refcount. However, lookup operations will</span>
+<span class="Comment">//: transparently drop the 'shared' and access to the refcount. Copying</span>
+<span class="Comment">//: between shared and non-shared addresses is forbidden.</span>
+<span class="Delimiter">:(before &quot;End Mu Types Initialization&quot;)</span>
+type_ordinal shared = put<span class="Delimiter">(</span>Type_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;shared&quot;</span><span class="Delimiter">,</span> Next_type_ordinal++<span class="Delimiter">);</span>
+get_or_insert<span class="Delimiter">(</span>Type<span class="Delimiter">,</span> shared<span class="Delimiter">).</span>name = <span class="Constant">&quot;shared&quot;</span><span class="Delimiter">;</span>
+<span class="Delimiter">:(before &quot;End Drop Address In lookup_memory(x)&quot;)</span>
+if <span class="Delimiter">(</span>x<span class="Delimiter">.</span>properties<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>second<span class="Delimiter">-&gt;</span>value == <span class="Constant">&quot;shared&quot;</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
+  trace<span class="Delimiter">(</span><span class="Constant">9999</span><span class="Delimiter">,</span> <span class="Constant">&quot;mem&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;skipping refcount at &quot;</span> &lt;&lt; x<span class="Delimiter">.</span>value &lt;&lt; end<span class="Delimiter">();</span>
+  x<span class="Delimiter">.</span>set_value<span class="Delimiter">(</span>x<span class="Delimiter">.</span>value+<span class="Constant">1</span><span class="Delimiter">);</span>  <span class="Comment">// skip refcount</span>
+  drop_from_type<span class="Delimiter">(</span>x<span class="Delimiter">,</span> <span class="Constant">&quot;shared&quot;</span><span class="Delimiter">);</span>
+<span class="Delimiter">}</span>
+<span class="Delimiter">:(before &quot;End Drop Address In canonize_type(r)&quot;)</span>
+if <span class="Delimiter">(</span>r<span class="Delimiter">.</span>properties<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>second<span class="Delimiter">-&gt;</span>value == <span class="Constant">&quot;shared&quot;</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
+  drop_from_type<span class="Delimiter">(</span>r<span class="Delimiter">,</span> <span class="Constant">&quot;shared&quot;</span><span class="Delimiter">);</span>
+<span class="Delimiter">}</span>
+
+<span class="Delimiter">:(scenarios run)</span>
+<span class="Delimiter">:(scenario new)</span>
+<span class="Comment"># call new two times with identical arguments; you should get back different results</span>
+recipe main [
+  <span class="Constant">1</span>:address:shared:number/<span class="Special">raw &lt;- </span>new number:type
+  <span class="Constant">2</span>:address:shared:number/<span class="Special">raw &lt;- </span>new number:type
+  <span class="Constant">3</span>:boolean/<span class="Special">raw &lt;- </span>equal <span class="Constant">1</span>:address:shared:number/<span class="Special">raw</span><span class="Delimiter">,</span> <span class="Constant">2</span>:address:shared:number/<span class="Special">raw</span>
+]
+<span class="traceContains">+mem: storing 0 in location 3</span>
+
+<span class="Delimiter">:(before &quot;End Globals&quot;)</span>
+long long int Memory_allocated_until = Reserved_for_tests<span class="Delimiter">;</span>
+long long int Initial_memory_per_routine = <span class="Constant">100000</span><span class="Delimiter">;</span>
+<span class="Delimiter">:(before &quot;End Setup&quot;)</span>
+Memory_allocated_until = Reserved_for_tests<span class="Delimiter">;</span>
+Initial_memory_per_routine = <span class="Constant">100000</span><span class="Delimiter">;</span>
+<span class="Delimiter">:(before &quot;End routine Fields&quot;)</span>
+long long int alloc<span class="Delimiter">,</span> alloc_max<span class="Delimiter">;</span>
+<span class="Delimiter">:(before &quot;End routine Constructor&quot;)</span>
+alloc = Memory_allocated_until<span class="Delimiter">;</span>
+Memory_allocated_until += Initial_memory_per_routine<span class="Delimiter">;</span>
+alloc_max = Memory_allocated_until<span class="Delimiter">;</span>
+trace<span class="Delimiter">(</span><span class="Constant">9999</span><span class="Delimiter">,</span> <span class="Constant">&quot;new&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;routine allocated memory from &quot;</span> &lt;&lt; alloc &lt;&lt; <span class="Constant">&quot; to &quot;</span> &lt;&lt; alloc_max &lt;&lt; end<span class="Delimiter">();</span>
+
+<span class="SalientComment">//:: 'new' takes a weird 'type' as its first ingredient; don't error on it</span>
+<span class="Delimiter">:(before &quot;End Mu Types Initialization&quot;)</span>
+put<span class="Delimiter">(</span>Type_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;type&quot;</span><span class="Delimiter">,</span> <span class="Constant">0</span><span class="Delimiter">);</span>
+
+<span class="SalientComment">//:: typecheck 'new' instructions</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Declarations&quot;)</span>
+NEW<span class="Delimiter">,</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Numbers&quot;)</span>
+put<span class="Delimiter">(</span>Recipe_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;new&quot;</span><span class="Delimiter">,</span> NEW<span class="Delimiter">);</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Checks&quot;)</span>
+case NEW: <span class="Delimiter">{</span>
+  const recipe&amp; caller = get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">);</span>
+  if <span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>empty<span class="Delimiter">()</span> || SIZE<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">)</span> &gt; <span class="Constant">2</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    raise_error &lt;&lt; maybe<span class="Delimiter">(</span>caller<span class="Delimiter">.</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;'new' requires one or two ingredients, but got &quot;</span> &lt;&lt; inst<span class="Delimiter">.</span>to_string<span class="Delimiter">()</span> &lt;&lt; <span class="cSpecial">'\n'</span> &lt;&lt; end<span class="Delimiter">();</span>
+    <span class="Identifier">break</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  <span class="Comment">// End NEW Check Special-cases</span>
+  reagent type = inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">);</span>
+  if <span class="Delimiter">(</span>!is_mu_type_literal<span class="Delimiter">(</span>type<span class="Delimiter">))</span> <span class="Delimiter">{</span>
+    raise_error &lt;&lt; maybe<span class="Delimiter">(</span>caller<span class="Delimiter">.</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;first ingredient of 'new' should be a type, but got &quot;</span> &lt;&lt; type<span class="Delimiter">.</span>original_string &lt;&lt; <span class="cSpecial">'\n'</span> &lt;&lt; end<span class="Delimiter">();</span>
+    <span class="Identifier">break</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  if <span class="Delimiter">(</span>inst<span class="Delimiter">.</span>products<span class="Delimiter">.</span>empty<span class="Delimiter">())</span> <span class="Delimiter">{</span>
+    raise_error &lt;&lt; maybe<span class="Delimiter">(</span>caller<span class="Delimiter">.</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;result of 'new' should never be ignored</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> &lt;&lt; end<span class="Delimiter">();</span>
+    <span class="Identifier">break</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  reagent product<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>products<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">));</span>
+  canonize_type<span class="Delimiter">(</span>product<span class="Delimiter">);</span>
+  drop_from_type<span class="Delimiter">(</span>product<span class="Delimiter">,</span> <span class="Constant">&quot;address&quot;</span><span class="Delimiter">);</span>
+  drop_from_type<span class="Delimiter">(</span>product<span class="Delimiter">,</span> <span class="Constant">&quot;shared&quot;</span><span class="Delimiter">);</span>
+  if <span class="Delimiter">(</span>SIZE<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">)</span> &gt; <span class="Constant">1</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    <span class="Comment">// array allocation</span>
+    drop_from_type<span class="Delimiter">(</span>product<span class="Delimiter">,</span> <span class="Constant">&quot;array&quot;</span><span class="Delimiter">);</span>
+  <span class="Delimiter">}</span>
+  reagent expected_product<span class="Delimiter">(</span><span class="Constant">&quot;x:&quot;</span>+type<span class="Delimiter">.</span>name<span class="Delimiter">);</span>
+  <span class="Comment">// End Post-processing(expected_product) When Checking 'new'</span>
+  if <span class="Delimiter">(</span>!types_strictly_match<span class="Delimiter">(</span>product<span class="Delimiter">,</span> expected_product<span class="Delimiter">))</span> <span class="Delimiter">{</span>
+    raise_error &lt;&lt; maybe<span class="Delimiter">(</span>caller<span class="Delimiter">.</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;product of 'new' has incorrect type: &quot;</span> &lt;&lt; inst<span class="Delimiter">.</span>to_string<span class="Delimiter">()</span> &lt;&lt; <span class="cSpecial">'\n'</span> &lt;&lt; end<span class="Delimiter">();</span>
+    <span class="Identifier">break</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="SalientComment">//:: translate 'new' to 'allocate' instructions that take a size instead of a type</span>
+<span class="Delimiter">:(after &quot;Transform.push_back(check_instruction)&quot;)</span>  <span class="Comment">// check_instruction will guard against direct 'allocate' instructions below</span>
+Transform<span class="Delimiter">.</span>push_back<span class="Delimiter">(</span>transform_new_to_allocate<span class="Delimiter">);</span>  <span class="Comment">// idempotent</span>
+
+<span class="Delimiter">:(code)</span>
+void transform_new_to_allocate<span class="Delimiter">(</span>const recipe_ordinal r<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+  trace<span class="Delimiter">(</span><span class="Constant">9991</span><span class="Delimiter">,</span> <span class="Constant">&quot;transform&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;--- convert 'new' to 'allocate' for recipe &quot;</span> &lt;&lt; get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">).</span>name &lt;&lt; end<span class="Delimiter">();</span>
+<span class="CommentedCode">//?   cerr &lt;&lt; &quot;--- convert 'new' to 'allocate' for recipe &quot; &lt;&lt; get(Recipe, r).name &lt;&lt; '\n';</span>
+  for <span class="Delimiter">(</span>long long int i = <span class="Constant">0</span><span class="Delimiter">;</span> i &lt; SIZE<span class="Delimiter">(</span>get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">).</span>steps<span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    instruction&amp; inst = get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">).</span>steps<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">);</span>
+    <span class="Comment">// Convert 'new' To 'allocate'</span>
+    if <span class="Delimiter">(</span>inst<span class="Delimiter">.</span>name == <span class="Constant">&quot;new&quot;</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
+      inst<span class="Delimiter">.</span>operation = ALLOCATE<span class="Delimiter">;</span>
+      string_tree* type_name = new string_tree<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>name<span class="Delimiter">);</span>
+      <span class="Comment">// End Post-processing(type_name) When Converting 'new'</span>
+      type_tree* type = new_type_tree<span class="Delimiter">(</span>type_name<span class="Delimiter">);</span>
+      inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>set_value<span class="Delimiter">(</span>size_of<span class="Delimiter">(</span>type<span class="Delimiter">));</span>
+      trace<span class="Delimiter">(</span><span class="Constant">9992</span><span class="Delimiter">,</span> <span class="Constant">&quot;new&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;size of &quot;</span> &lt;&lt; debug_string<span class="Delimiter">(</span>type_name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot; is &quot;</span> &lt;&lt; inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>value &lt;&lt; end<span class="Delimiter">();</span>
+      delete type<span class="Delimiter">;</span>
+      delete type_name<span class="Delimiter">;</span>
+    <span class="Delimiter">}</span>
+  <span class="Delimiter">}</span>
+<span class="Delimiter">}</span>
+
+<span class="SalientComment">//:: implement 'allocate' based on size</span>
+
+<span class="Delimiter">:(before &quot;End Primitive Recipe Declarations&quot;)</span>
+ALLOCATE<span class="Delimiter">,</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Numbers&quot;)</span>
+put<span class="Delimiter">(</span>Recipe_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;allocate&quot;</span><span class="Delimiter">,</span> ALLOCATE<span class="Delimiter">);</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Implementations&quot;)</span>
+case ALLOCATE: <span class="Delimiter">{</span>
+  <span class="Comment">// compute the space we need</span>
+  long long int size = ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">);</span>
+  if <span class="Delimiter">(</span>SIZE<span class="Delimiter">(</span>ingredients<span class="Delimiter">)</span> &gt; <span class="Constant">1</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    <span class="Comment">// array</span>
+    trace<span class="Delimiter">(</span><span class="Constant">9999</span><span class="Delimiter">,</span> <span class="Constant">&quot;mem&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;array size is &quot;</span> &lt;&lt; ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">).</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">)</span> &lt;&lt; end<span class="Delimiter">();</span>
+    size = <span class="Comment">/*</span><span class="Comment">space for length</span><span class="Comment">*/</span><span class="Constant">1</span> + size*ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">).</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">);</span>
+  <span class="Delimiter">}</span>
+  <span class="Comment">// include space for refcount</span>
+  size++<span class="Delimiter">;</span>
+  trace<span class="Delimiter">(</span><span class="Constant">9999</span><span class="Delimiter">,</span> <span class="Constant">&quot;mem&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;allocating size &quot;</span> &lt;&lt; size &lt;&lt; end<span class="Delimiter">();</span>
+<span class="CommentedCode">//?   Total_alloc += size;</span>
+<span class="CommentedCode">//?   Num_alloc++;</span>
+  <span class="Comment">// compute the region of memory to return</span>
+  <span class="Comment">// really crappy at the moment</span>
+  ensure_space<span class="Delimiter">(</span>size<span class="Delimiter">);</span>
+  const long long int result = Current_routine<span class="Delimiter">-&gt;</span>alloc<span class="Delimiter">;</span>
+  trace<span class="Delimiter">(</span><span class="Constant">9999</span><span class="Delimiter">,</span> <span class="Constant">&quot;mem&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;new alloc: &quot;</span> &lt;&lt; result &lt;&lt; end<span class="Delimiter">();</span>
+  <span class="Comment">// save result</span>
+  products<span class="Delimiter">.</span>resize<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">);</span>
+  products<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>push_back<span class="Delimiter">(</span>result<span class="Delimiter">);</span>
+  <span class="Comment">// initialize allocated space</span>
+  for <span class="Delimiter">(</span>long long int address = result<span class="Delimiter">;</span> address &lt; result+size<span class="Delimiter">;</span> ++address<span class="Delimiter">)</span>
+    put<span class="Delimiter">(</span>Memory<span class="Delimiter">,</span> address<span class="Delimiter">,</span> <span class="Constant">0</span><span class="Delimiter">);</span>
+  <span class="Comment">// initialize array length</span>
+  if <span class="Delimiter">(</span>SIZE<span class="Delimiter">(</span>current_instruction<span class="Delimiter">().</span>ingredients<span class="Delimiter">)</span> &gt; <span class="Constant">1</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    trace<span class="Delimiter">(</span><span class="Constant">9999</span><span class="Delimiter">,</span> <span class="Constant">&quot;mem&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;storing &quot;</span> &lt;&lt; ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">).</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot; in location &quot;</span> &lt;&lt; result+<span class="Comment">/*</span><span class="Comment">skip refcount</span><span class="Comment">*/</span><span class="Constant">1</span> &lt;&lt; end<span class="Delimiter">();</span>
+    put<span class="Delimiter">(</span>Memory<span class="Delimiter">,</span> result+<span class="Comment">/*</span><span class="Comment">skip refcount</span><span class="Comment">*/</span><span class="Constant">1</span><span class="Delimiter">,</span> ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">).</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">));</span>
+  <span class="Delimiter">}</span>
+  <span class="Comment">// bump</span>
+  Current_routine<span class="Delimiter">-&gt;</span>alloc += size<span class="Delimiter">;</span>
+  <span class="Comment">// no support for reclaiming memory</span>
+  assert<span class="Delimiter">(</span>Current_routine<span class="Delimiter">-&gt;</span>alloc &lt;= Current_routine<span class="Delimiter">-&gt;</span>alloc_max<span class="Delimiter">);</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="SalientComment">//:: ensure we never call 'allocate' directly; its types are not checked</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Checks&quot;)</span>
+case ALLOCATE: <span class="Delimiter">{</span>
+  raise &lt;&lt; <span class="Constant">&quot;never call 'allocate' directly'; always use 'new'</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> &lt;&lt; end<span class="Delimiter">();</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="SalientComment">//:: ensure we never call 'new' without translating it (unless we add special-cases later)</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Implementations&quot;)</span>
+case NEW: <span class="Delimiter">{</span>
+  raise &lt;&lt; <span class="Constant">&quot;no implementation for 'new'; why wasn't it translated to 'allocate'?</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> &lt;&lt; end<span class="Delimiter">();</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="CommentedCode">//? :(before &quot;End Globals&quot;)</span>
+<span class="CommentedCode">//? long long int Total_alloc = 0;</span>
+<span class="CommentedCode">//? long long int Num_alloc = 0;</span>
+<span class="CommentedCode">//? long long int Total_free = 0;</span>
+<span class="CommentedCode">//? long long int Num_free = 0;</span>
+<span class="CommentedCode">//? :(before &quot;End Setup&quot;)</span>
+<span class="CommentedCode">//? Total_alloc = Num_alloc = Total_free = Num_free = 0;</span>
+<span class="CommentedCode">//? :(before &quot;End Teardown&quot;)</span>
+<span class="CommentedCode">//? cerr &lt;&lt; Total_alloc &lt;&lt; &quot;/&quot; &lt;&lt; Num_alloc</span>
+<span class="CommentedCode">//?      &lt;&lt; &quot; vs &quot; &lt;&lt; Total_free &lt;&lt; &quot;/&quot; &lt;&lt; Num_free &lt;&lt; '\n';</span>
+<span class="CommentedCode">//? cerr &lt;&lt; SIZE(Memory) &lt;&lt; '\n';</span>
+
+<span class="Delimiter">:(code)</span>
+void ensure_space<span class="Delimiter">(</span>long long int size<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+  if <span class="Delimiter">(</span>size &gt; Initial_memory_per_routine<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    tb_shutdown<span class="Delimiter">();</span>
+    cerr &lt;&lt; <span class="Constant">&quot;can't allocate &quot;</span> &lt;&lt; size &lt;&lt; <span class="Constant">&quot; locations, that's too much compared to &quot;</span> &lt;&lt; Initial_memory_per_routine &lt;&lt; <span class="Constant">&quot;.</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span><span class="Delimiter">;</span>
+    exit<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">);</span>
+  <span class="Delimiter">}</span>
+  if <span class="Delimiter">(</span>Current_routine<span class="Delimiter">-&gt;</span>alloc + size &gt; Current_routine<span class="Delimiter">-&gt;</span>alloc_max<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    <span class="Comment">// waste the remaining space and create a new chunk</span>
+    Current_routine<span class="Delimiter">-&gt;</span>alloc = Memory_allocated_until<span class="Delimiter">;</span>
+    Memory_allocated_until += Initial_memory_per_routine<span class="Delimiter">;</span>
+    Current_routine<span class="Delimiter">-&gt;</span>alloc_max = Memory_allocated_until<span class="Delimiter">;</span>
+    trace<span class="Delimiter">(</span><span class="Constant">9999</span><span class="Delimiter">,</span> <span class="Constant">&quot;new&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;routine allocated memory from &quot;</span> &lt;&lt; Current_routine<span class="Delimiter">-&gt;</span>alloc &lt;&lt; <span class="Constant">&quot; to &quot;</span> &lt;&lt; Current_routine<span class="Delimiter">-&gt;</span>alloc_max &lt;&lt; end<span class="Delimiter">();</span>
+  <span class="Delimiter">}</span>
+<span class="Delimiter">}</span>
+
+<span class="Delimiter">:(scenario new_initializes)</span>
+<span class="Special">% Memory_allocated_until = 10;</span>
+<span class="Special">% put(Memory, Memory_allocated_until, 1);</span>
+recipe main [
+  <span class="Constant">1</span>:address:shared:number<span class="Special"> &lt;- </span>new number:type
+  <span class="Constant">2</span>:number<span class="Special"> &lt;- </span>copy *<span class="Constant">1</span>:address:shared:number
+]
+<span class="traceContains">+mem: storing 0 in location 2</span>
+
+<span class="Delimiter">:(scenario new_array)</span>
+recipe main [
+  <span class="Constant">1</span>:address:shared:array:number/<span class="Special">raw &lt;- </span>new number:type<span class="Delimiter">,</span> <span class="Constant">5</span>
+  <span class="Constant">2</span>:address:shared:number/<span class="Special">raw &lt;- </span>new number:type
+  <span class="Constant">3</span>:number/<span class="Special">raw &lt;- </span>subtract <span class="Constant">2</span>:address:shared:number/<span class="Special">raw</span><span class="Delimiter">,</span> <span class="Constant">1</span>:address:shared:array:number/<span class="Special">raw</span>
+]
+<span class="traceContains">+run: 1:address:shared:array:number/raw &lt;- new number:type, 5</span>
+<span class="traceContains">+mem: array size is 5</span>
+<span class="Comment"># don't forget the extra location for array size, and the second extra location for the refcount</span>
+<span class="traceContains">+mem: storing 7 in location 3</span>
+
+<span class="Delimiter">:(scenario new_empty_array)</span>
+recipe main [
+  <span class="Constant">1</span>:address:shared:array:number/<span class="Special">raw &lt;- </span>new number:type<span class="Delimiter">,</span> <span class="Constant">0</span>
+  <span class="Constant">2</span>:address:shared:number/<span class="Special">raw &lt;- </span>new number:type
+  <span class="Constant">3</span>:number/<span class="Special">raw &lt;- </span>subtract <span class="Constant">2</span>:address:shared:number/<span class="Special">raw</span><span class="Delimiter">,</span> <span class="Constant">1</span>:address:shared:array:number/<span class="Special">raw</span>
+]
+<span class="traceContains">+run: 1:address:shared:array:number/raw &lt;- new number:type, 0</span>
+<span class="traceContains">+mem: array size is 0</span>
+<span class="Comment"># one location for array size, and one for the refcount</span>
+<span class="traceContains">+mem: storing 2 in location 3</span>
+
+<span class="Comment">//: If a routine runs out of its initial allocation, it should allocate more.</span>
+<span class="Delimiter">:(scenario new_overflow)</span>
+<span class="Special">% Initial_memory_per_routine = 3;  // barely enough room for point allocation below</span>
+recipe main [
+  <span class="Constant">1</span>:address:shared:number/<span class="Special">raw &lt;- </span>new number:type
+  <span class="Constant">2</span>:address:shared:point/<span class="Special">raw &lt;- </span>new point:type  <span class="Comment"># not enough room in initial page</span>
+]
+<span class="traceContains">+new: routine allocated memory from 1000 to 1003</span>
+<span class="traceContains">+new: routine allocated memory from 1003 to 1006</span>
+
+<span class="SalientComment">//:: A way to return memory, and to reuse reclaimed memory.</span>
+<span class="Comment">//: todo: custodians, etc. Following malloc/free is a temporary hack.</span>
+
+<span class="Delimiter">:(scenario new_reclaim)</span>
+recipe main [
+  <span class="Constant">1</span>:address:shared:number<span class="Special"> &lt;- </span>new number:type
+  <span class="Constant">2</span>:address:shared:number<span class="Special"> &lt;- </span>copy <span class="Constant">1</span>:address:shared:number  <span class="Comment"># because 1 will get reset during abandon below</span>
+  abandon <span class="Constant">1</span>:address:shared:number  <span class="Comment"># unsafe</span>
+  <span class="Constant">3</span>:address:shared:number<span class="Special"> &lt;- </span>new number:type  <span class="Comment"># must be same size as abandoned memory to reuse</span>
+  <span class="Constant">4</span>:boolean<span class="Special"> &lt;- </span>equal <span class="Constant">2</span>:address:shared:number<span class="Delimiter">,</span> <span class="Constant">3</span>:address:shared:number
+]
+<span class="Comment"># both allocations should have returned the same address</span>
+<span class="traceContains">+mem: storing 1 in location 4</span>
+
+<span class="Delimiter">:(before &quot;End Globals&quot;)</span>
+map&lt;long long int<span class="Delimiter">,</span> long long int&gt; Free_list<span class="Delimiter">;</span>
+<span class="Delimiter">:(before &quot;End Setup&quot;)</span>
+Free_list<span class="Delimiter">.</span>clear<span class="Delimiter">();</span>
+
+<span class="Delimiter">:(before &quot;End Primitive Recipe Declarations&quot;)</span>
+ABANDON<span class="Delimiter">,</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Numbers&quot;)</span>
+put<span class="Delimiter">(</span>Recipe_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;abandon&quot;</span><span class="Delimiter">,</span> ABANDON<span class="Delimiter">);</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Checks&quot;)</span>
+case ABANDON: <span class="Delimiter">{</span>
+  if <span class="Delimiter">(</span>SIZE<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">)</span> != <span class="Constant">1</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    raise_error &lt;&lt; maybe<span class="Delimiter">(</span>get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">).</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;'abandon' requires one ingredient, but got '&quot;</span> &lt;&lt; inst<span class="Delimiter">.</span>to_string<span class="Delimiter">()</span> &lt;&lt; <span class="Constant">&quot;'</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> &lt;&lt; end<span class="Delimiter">();</span>
+    <span class="Identifier">break</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  reagent types = inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">);</span>
+  canonize_type<span class="Delimiter">(</span>types<span class="Delimiter">);</span>
+  if <span class="Delimiter">(</span>!types<span class="Delimiter">.</span>type || types<span class="Delimiter">.</span>type<span class="Delimiter">-&gt;</span>value != get<span class="Delimiter">(</span>Type_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;address&quot;</span><span class="Delimiter">)</span> || types<span class="Delimiter">.</span>type<span class="Delimiter">-&gt;</span>right<span class="Delimiter">-&gt;</span>value != get<span class="Delimiter">(</span>Type_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;shared&quot;</span><span class="Delimiter">))</span> <span class="Delimiter">{</span>
+    raise_error &lt;&lt; maybe<span class="Delimiter">(</span>get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">).</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;first ingredient of 'abandon' should be an address:shared:___, but got &quot;</span> &lt;&lt; inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>original_string &lt;&lt; <span class="cSpecial">'\n'</span> &lt;&lt; end<span class="Delimiter">();</span>
+    <span class="Identifier">break</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Implementations&quot;)</span>
+case ABANDON: <span class="Delimiter">{</span>
+  long long int address = ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">);</span>
+  trace<span class="Delimiter">(</span><span class="Constant">9999</span><span class="Delimiter">,</span> <span class="Constant">&quot;abandon&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;address to abandon is &quot;</span> &lt;&lt; address &lt;&lt; end<span class="Delimiter">();</span>
+  reagent types = current_instruction<span class="Delimiter">().</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">);</span>
+  trace<span class="Delimiter">(</span><span class="Constant">9999</span><span class="Delimiter">,</span> <span class="Constant">&quot;abandon&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;value of ingredient is &quot;</span> &lt;&lt; types<span class="Delimiter">.</span>value &lt;&lt; end<span class="Delimiter">();</span>
+  canonize<span class="Delimiter">(</span>types<span class="Delimiter">);</span>
+  <span class="Comment">// lookup_memory without drop_one_lookup {</span>
+  trace<span class="Delimiter">(</span><span class="Constant">9999</span><span class="Delimiter">,</span> <span class="Constant">&quot;abandon&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;value of ingredient after canonization is &quot;</span> &lt;&lt; types<span class="Delimiter">.</span>value &lt;&lt; end<span class="Delimiter">();</span>
+  long long int address_location = types<span class="Delimiter">.</span>value<span class="Delimiter">;</span>
+  types<span class="Delimiter">.</span>set_value<span class="Delimiter">(</span>get_or_insert<span class="Delimiter">(</span>Memory<span class="Delimiter">,</span> types<span class="Delimiter">.</span>value<span class="Delimiter">)</span>+<span class="Comment">/*</span><span class="Comment">skip refcount</span><span class="Comment">*/</span><span class="Constant">1</span><span class="Delimiter">);</span>
+  drop_from_type<span class="Delimiter">(</span>types<span class="Delimiter">,</span> <span class="Constant">&quot;address&quot;</span><span class="Delimiter">);</span>
+  drop_from_type<span class="Delimiter">(</span>types<span class="Delimiter">,</span> <span class="Constant">&quot;shared&quot;</span><span class="Delimiter">);</span>
+  <span class="Comment">// }</span>
+  abandon<span class="Delimiter">(</span>address<span class="Delimiter">,</span> size_of<span class="Delimiter">(</span>types<span class="Delimiter">)</span>+<span class="Comment">/*</span><span class="Comment">refcount</span><span class="Comment">*/</span><span class="Constant">1</span><span class="Delimiter">);</span>
+  <span class="Comment">// clear the address</span>
+  trace<span class="Delimiter">(</span><span class="Constant">9999</span><span class="Delimiter">,</span> <span class="Constant">&quot;mem&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;resetting location &quot;</span> &lt;&lt; address_location &lt;&lt; end<span class="Delimiter">();</span>
+  Memory[address_location] = <span class="Constant">0</span><span class="Delimiter">;</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="Delimiter">:(code)</span>
+void abandon<span class="Delimiter">(</span>long long int address<span class="Delimiter">,</span> long long int size<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+  trace<span class="Delimiter">(</span><span class="Constant">9999</span><span class="Delimiter">,</span> <span class="Constant">&quot;abandon&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;saving in free-list of size &quot;</span> &lt;&lt; size &lt;&lt; end<span class="Delimiter">();</span>
+<span class="CommentedCode">//?   Total_free += size;</span>
+<span class="CommentedCode">//?   Num_free++;</span>
+<span class="CommentedCode">//?   cerr &lt;&lt; &quot;abandon: &quot; &lt;&lt; size &lt;&lt; '\n';</span>
+  <span class="Comment">// clear memory</span>
+  for <span class="Delimiter">(</span>long long int curr = address<span class="Delimiter">;</span> curr &lt; address+size<span class="Delimiter">;</span> ++curr<span class="Delimiter">)</span>
+    put<span class="Delimiter">(</span>Memory<span class="Delimiter">,</span> curr<span class="Delimiter">,</span> <span class="Constant">0</span><span class="Delimiter">);</span>
+  <span class="Comment">// append existing free list to address</span>
+  put<span class="Delimiter">(</span>Memory<span class="Delimiter">,</span> address<span class="Delimiter">,</span> Free_list[size]<span class="Delimiter">);</span>
+  Free_list[size] = address<span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="Delimiter">:(before &quot;ensure_space(size)&quot; following &quot;case ALLOCATE&quot;)</span>
+if <span class="Delimiter">(</span>Free_list[size]<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+  trace<span class="Delimiter">(</span><span class="Constant">9999</span><span class="Delimiter">,</span> <span class="Constant">&quot;abandon&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;picking up space from free-list of size &quot;</span> &lt;&lt; size &lt;&lt; end<span class="Delimiter">();</span>
+  long long int result = Free_list[size]<span class="Delimiter">;</span>
+  Free_list[size] = get_or_insert<span class="Delimiter">(</span>Memory<span class="Delimiter">,</span> result<span class="Delimiter">);</span>
+  for <span class="Delimiter">(</span>long long int curr = result+<span class="Constant">1</span><span class="Delimiter">;</span> curr &lt; result+size<span class="Delimiter">;</span> ++curr<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    if <span class="Delimiter">(</span>get_or_insert<span class="Delimiter">(</span>Memory<span class="Delimiter">,</span> curr<span class="Delimiter">)</span> != <span class="Constant">0</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
+      raise_error &lt;&lt; maybe<span class="Delimiter">(</span>current_recipe_name<span class="Delimiter">())</span> &lt;&lt; <span class="Constant">&quot;memory in free list was not zeroed out: &quot;</span> &lt;&lt; curr &lt;&lt; <span class="Constant">'/'</span> &lt;&lt; result &lt;&lt; <span class="Constant">&quot;; somebody wrote to us after free!!!</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> &lt;&lt; end<span class="Delimiter">();</span>
+      <span class="Identifier">break</span><span class="Delimiter">;</span>  <span class="Comment">// always fatal</span>
+    <span class="Delimiter">}</span>
+  <span class="Delimiter">}</span>
+  if <span class="Delimiter">(</span>SIZE<span class="Delimiter">(</span>current_instruction<span class="Delimiter">().</span>ingredients<span class="Delimiter">)</span> &gt; <span class="Constant">1</span><span class="Delimiter">)</span>
+    put<span class="Delimiter">(</span>Memory<span class="Delimiter">,</span> result+<span class="Comment">/*</span><span class="Comment">skip refcount</span><span class="Comment">*/</span><span class="Constant">1</span><span class="Delimiter">,</span> ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">).</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">));</span>
+  else
+    put<span class="Delimiter">(</span>Memory<span class="Delimiter">,</span> result<span class="Delimiter">,</span> <span class="Constant">0</span><span class="Delimiter">);</span>
+  products<span class="Delimiter">.</span>resize<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">);</span>
+  products<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>push_back<span class="Delimiter">(</span>result<span class="Delimiter">);</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="Delimiter">:(scenario new_differing_size_no_reclaim)</span>
+recipe main [
+  <span class="Constant">1</span>:address:shared:number<span class="Special"> &lt;- </span>new number:type
+  <span class="Constant">2</span>:address:shared:number<span class="Special"> &lt;- </span>copy <span class="Constant">1</span>:address:shared:number
+  abandon <span class="Constant">1</span>:address:shared:number
+  <span class="Constant">3</span>:address:shared:array:number<span class="Special"> &lt;- </span>new number:type<span class="Delimiter">,</span> <span class="Constant">2</span>  <span class="Comment"># different size</span>
+  <span class="Constant">4</span>:boolean<span class="Special"> &lt;- </span>equal <span class="Constant">2</span>:address:shared:number<span class="Delimiter">,</span> <span class="Constant">3</span>:address:shared:array:number
+]
+<span class="Comment"># no reuse</span>
+<span class="traceContains">+mem: storing 0 in location 4</span>
+
+<span class="Delimiter">:(scenario new_reclaim_array)</span>
+recipe main [
+  <span class="Constant">1</span>:address:shared:array:number<span class="Special"> &lt;- </span>new number:type<span class="Delimiter">,</span> <span class="Constant">2</span>
+  <span class="Constant">2</span>:address:shared:array:number<span class="Special"> &lt;- </span>copy <span class="Constant">1</span>:address:shared:array:number
+  abandon <span class="Constant">1</span>:address:shared:array:number  <span class="Comment"># unsafe</span>
+  <span class="Constant">3</span>:address:shared:array:number<span class="Special"> &lt;- </span>new number:type<span class="Delimiter">,</span> <span class="Constant">2</span>
+  <span class="Constant">4</span>:boolean<span class="Special"> &lt;- </span>equal <span class="Constant">2</span>:address:shared:array:number<span class="Delimiter">,</span> <span class="Constant">3</span>:address:shared:array:number
+]
+<span class="Comment"># reuse</span>
+<span class="traceContains">+mem: storing 1 in location 4</span>
+
+<span class="Delimiter">:(scenario reset_on_abandon)</span>
+recipe main [
+  <span class="Constant">1</span>:address:shared:number<span class="Special"> &lt;- </span>new number:type
+  abandon <span class="Constant">1</span>:address:shared:number
+]
+<span class="Comment"># reuse</span>
+<span class="traceContains">+run: abandon 1:address:shared:number</span>
+<span class="traceContains">+mem: resetting location 1</span>
+
+<span class="SalientComment">//:: Manage refcounts when copying addresses.</span>
+
+<span class="Delimiter">:(scenario refcounts)</span>
+recipe main [
+  <span class="Constant">1</span>:address:shared:number<span class="Special"> &lt;- </span>copy <span class="Constant">1000</span>/unsafe
+  <span class="Constant">2</span>:address:shared:number<span class="Special"> &lt;- </span>copy <span class="Constant">1</span>:address:shared:number
+  <span class="Constant">1</span>:address:shared:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
+  <span class="Constant">2</span>:address:shared:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
+]
+<span class="traceContains">+run: 1:address:shared:number &lt;- copy 1000/unsafe</span>
+<span class="traceContains">+mem: incrementing refcount of 1000: 0 -&gt; 1</span>
+<span class="traceContains">+run: 2:address:shared:number &lt;- copy 1:address:shared:number</span>
+<span class="traceContains">+mem: incrementing refcount of 1000: 1 -&gt; 2</span>
+<span class="traceContains">+run: 1:address:shared:number &lt;- copy 0</span>
+<span class="traceContains">+mem: decrementing refcount of 1000: 2 -&gt; 1</span>
+<span class="traceContains">+run: 2:address:shared:number &lt;- copy 0</span>
+<span class="traceContains">+mem: decrementing refcount of 1000: 1 -&gt; 0</span>
+<span class="Comment"># the /unsafe corrupts memory but fortunately we won't be running any more 'new' in this scenario</span>
+<span class="traceContains">+mem: automatically abandoning 1000</span>
+
+<span class="Delimiter">:(before &quot;End write_memory(reagent x, long long int base) Special-cases&quot;)</span>
+if <span class="Delimiter">(</span>x<span class="Delimiter">.</span>type<span class="Delimiter">-&gt;</span>value == get<span class="Delimiter">(</span>Type_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;address&quot;</span><span class="Delimiter">)</span>
+    &amp;&amp; x<span class="Delimiter">.</span>type<span class="Delimiter">-&gt;</span>right
+    &amp;&amp; x<span class="Delimiter">.</span>type<span class="Delimiter">-&gt;</span>right<span class="Delimiter">-&gt;</span>value == get<span class="Delimiter">(</span>Type_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;shared&quot;</span><span class="Delimiter">))</span> <span class="Delimiter">{</span>
+  <span class="Comment">// compute old address of x, as well as new address we want to write in</span>
+  long long int old_address = get_or_insert<span class="Delimiter">(</span>Memory<span class="Delimiter">,</span> x<span class="Delimiter">.</span>value<span class="Delimiter">);</span>
+  assert<span class="Delimiter">(</span>scalar<span class="Delimiter">(</span>data<span class="Delimiter">));</span>
+  long long int new_address = data<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">);</span>
+  <span class="Comment">// decrement refcount of old address</span>
+  if <span class="Delimiter">(</span>old_address<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    long long int old_refcount = get_or_insert<span class="Delimiter">(</span>Memory<span class="Delimiter">,</span> old_address<span class="Delimiter">);</span>
+<span class="CommentedCode">//?     cerr &lt;&lt; old_refcount &lt;&lt; '\n';</span>
+<span class="CommentedCode">//?     assert(old_refcount &gt; 0);</span>
+    trace<span class="Delimiter">(</span><span class="Constant">9999</span><span class="Delimiter">,</span> <span class="Constant">&quot;mem&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;decrementing refcount of &quot;</span> &lt;&lt; old_address &lt;&lt; <span class="Constant">&quot;: &quot;</span> &lt;&lt; old_refcount &lt;&lt; <span class="Constant">&quot; -&gt; &quot;</span> &lt;&lt; <span class="Delimiter">(</span>old_refcount-<span class="Constant">1</span><span class="Delimiter">)</span> &lt;&lt; end<span class="Delimiter">();</span>
+    put<span class="Delimiter">(</span>Memory<span class="Delimiter">,</span> old_address<span class="Delimiter">,</span> old_refcount-<span class="Constant">1</span><span class="Delimiter">);</span>
+  <span class="Delimiter">}</span>
+  <span class="Comment">// perform the write</span>
+  trace<span class="Delimiter">(</span><span class="Constant">9999</span><span class="Delimiter">,</span> <span class="Constant">&quot;mem&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;storing &quot;</span> &lt;&lt; no_scientific<span class="Delimiter">(</span>data<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">))</span> &lt;&lt; <span class="Constant">&quot; in location &quot;</span> &lt;&lt; base &lt;&lt; end<span class="Delimiter">();</span>
+  put<span class="Delimiter">(</span>Memory<span class="Delimiter">,</span> base<span class="Delimiter">,</span> new_address<span class="Delimiter">);</span>
+  <span class="Comment">// increment refcount of new address</span>
+  if <span class="Delimiter">(</span>new_address<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    long long int new_refcount = get_or_insert<span class="Delimiter">(</span>Memory<span class="Delimiter">,</span> new_address<span class="Delimiter">);</span>
+<span class="CommentedCode">//?       assert(new_refcount &gt;= 0);  // == 0 only when new_address == old_address</span>
+    trace<span class="Delimiter">(</span><span class="Constant">9999</span><span class="Delimiter">,</span> <span class="Constant">&quot;mem&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;incrementing refcount of &quot;</span> &lt;&lt; new_address &lt;&lt; <span class="Constant">&quot;: &quot;</span> &lt;&lt; new_refcount &lt;&lt; <span class="Constant">&quot; -&gt; &quot;</span> &lt;&lt; <span class="Delimiter">(</span>new_refcount+<span class="Constant">1</span><span class="Delimiter">)</span> &lt;&lt; end<span class="Delimiter">();</span>
+    put<span class="Delimiter">(</span>Memory<span class="Delimiter">,</span> new_address<span class="Delimiter">,</span> new_refcount+<span class="Constant">1</span><span class="Delimiter">);</span>
+  <span class="Delimiter">}</span>
+  <span class="Comment">// abandon old address if necessary</span>
+  <span class="Comment">// do this after all refcount updates are done just in case old and new are identical</span>
+  <span class="Comment">// </span><span class="Todo">TODO</span><span class="Comment">: doesn't work yet</span>
+  assert<span class="Delimiter">(</span>get_or_insert<span class="Delimiter">(</span>Memory<span class="Delimiter">,</span> old_address<span class="Delimiter">)</span> &gt;= <span class="Constant">0</span><span class="Delimiter">);</span>
+  if <span class="Delimiter">(</span>old_address &amp;&amp; get_or_insert<span class="Delimiter">(</span>Memory<span class="Delimiter">,</span> old_address<span class="Delimiter">)</span> == <span class="Constant">0</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    <span class="Comment">// lookup_memory without drop_one_lookup {</span>
+    trace<span class="Delimiter">(</span><span class="Constant">9999</span><span class="Delimiter">,</span> <span class="Constant">&quot;mem&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;automatically abandoning &quot;</span> &lt;&lt; old_address &lt;&lt; end<span class="Delimiter">();</span>
+    trace<span class="Delimiter">(</span><span class="Constant">9999</span><span class="Delimiter">,</span> <span class="Constant">&quot;mem&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;computing size to abandon at &quot;</span> &lt;&lt; x<span class="Delimiter">.</span>value &lt;&lt; end<span class="Delimiter">();</span>
+    x<span class="Delimiter">.</span>set_value<span class="Delimiter">(</span>get_or_insert<span class="Delimiter">(</span>Memory<span class="Delimiter">,</span> x<span class="Delimiter">.</span>value<span class="Delimiter">)</span>+<span class="Comment">/*</span><span class="Comment">skip refcount</span><span class="Comment">*/</span><span class="Constant">1</span><span class="Delimiter">);</span>
+    drop_from_type<span class="Delimiter">(</span>x<span class="Delimiter">,</span> <span class="Constant">&quot;address&quot;</span><span class="Delimiter">);</span>
+    drop_from_type<span class="Delimiter">(</span>x<span class="Delimiter">,</span> <span class="Constant">&quot;shared&quot;</span><span class="Delimiter">);</span>
+    <span class="Comment">// }</span>
+    abandon<span class="Delimiter">(</span>old_address<span class="Delimiter">,</span> size_of<span class="Delimiter">(</span>x<span class="Delimiter">)</span>+<span class="Comment">/*</span><span class="Comment">refcount</span><span class="Comment">*/</span><span class="Constant">1</span><span class="Delimiter">);</span>
+  <span class="Delimiter">}</span>
+  <span class="Identifier">return</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="SalientComment">//:: Extend 'new' to handle a unicode string literal argument.</span>
+
+<span class="Delimiter">:(scenario new_string)</span>
+recipe main [
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new [abc def]
+  <span class="Constant">2</span>:character<span class="Special"> &lt;- </span>index *<span class="Constant">1</span>:address:shared:array:character<span class="Delimiter">,</span> <span class="Constant">5</span>
+]
+<span class="Comment"># number code for 'e'</span>
+<span class="traceContains">+mem: storing 101 in location 2</span>
+
+<span class="Delimiter">:(scenario new_string_handles_unicode)</span>
+recipe main [
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new [a«c]
+  <span class="Constant">2</span>:number<span class="Special"> &lt;- </span>length *<span class="Constant">1</span>:address:shared:array:character
+  <span class="Constant">3</span>:character<span class="Special"> &lt;- </span>index *<span class="Constant">1</span>:address:shared:array:character<span class="Delimiter">,</span> <span class="Constant">1</span>
+]
+<span class="traceContains">+mem: storing 3 in location 2</span>
+<span class="Comment"># unicode for '«'</span>
+<span class="traceContains">+mem: storing 171 in location 3</span>
+
+<span class="Delimiter">:(before &quot;End NEW Check Special-cases&quot;)</span>
+if <span class="Delimiter">(</span>is_literal_string<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">)))</span> <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">:(before &quot;Convert 'new' To 'allocate'&quot;)</span>
+if <span class="Delimiter">(</span>inst<span class="Delimiter">.</span>name == <span class="Constant">&quot;new&quot;</span> &amp;&amp; is_literal_string<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">)))</span> <span class="Identifier">continue</span><span class="Delimiter">;</span>
+<span class="Delimiter">:(after &quot;case NEW&quot; following &quot;Primitive Recipe Implementations&quot;)</span>
+  if <span class="Delimiter">(</span>is_literal_string<span class="Delimiter">(</span>current_instruction<span class="Delimiter">().</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">)))</span> <span class="Delimiter">{</span>
+    products<span class="Delimiter">.</span>resize<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">);</span>
+    products<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>push_back<span class="Delimiter">(</span>new_mu_string<span class="Delimiter">(</span>current_instruction<span class="Delimiter">().</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>name<span class="Delimiter">));</span>
+    <span class="Identifier">break</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+
+<span class="Delimiter">:(code)</span>
+long long int new_mu_string<span class="Delimiter">(</span>const string&amp; contents<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+  <span class="Comment">// allocate an array just large enough for it</span>
+  long long int string_length = unicode_length<span class="Delimiter">(</span>contents<span class="Delimiter">);</span>
+<span class="CommentedCode">//?   Total_alloc += string_length+1;</span>
+<span class="CommentedCode">//?   Num_alloc++;</span>
+  ensure_space<span class="Delimiter">(</span>string_length+<span class="Constant">1</span><span class="Delimiter">);</span>  <span class="Comment">// don't forget the extra location for array size</span>
+  <span class="Comment">// initialize string</span>
+  long long int result = Current_routine<span class="Delimiter">-&gt;</span>alloc<span class="Delimiter">;</span>
+  <span class="Comment">// initialize refcount</span>
+  put<span class="Delimiter">(</span>Memory<span class="Delimiter">,</span> Current_routine<span class="Delimiter">-&gt;</span>alloc++<span class="Delimiter">,</span> <span class="Constant">0</span><span class="Delimiter">);</span>
+  <span class="Comment">// store length</span>
+  put<span class="Delimiter">(</span>Memory<span class="Delimiter">,</span> Current_routine<span class="Delimiter">-&gt;</span>alloc++<span class="Delimiter">,</span> string_length<span class="Delimiter">);</span>
+  long long int curr = <span class="Constant">0</span><span class="Delimiter">;</span>
+  const char* raw_contents = contents<span class="Delimiter">.</span>c_str<span class="Delimiter">();</span>
+  for <span class="Delimiter">(</span>long long int i = <span class="Constant">0</span><span class="Delimiter">;</span> i &lt; string_length<span class="Delimiter">;</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    uint32_t curr_character<span class="Delimiter">;</span>
+    assert<span class="Delimiter">(</span>curr &lt; SIZE<span class="Delimiter">(</span>contents<span class="Delimiter">));</span>
+    tb_utf8_char_to_unicode<span class="Delimiter">(</span>&amp;curr_character<span class="Delimiter">,</span> &amp;raw_contents[curr]<span class="Delimiter">);</span>
+    put<span class="Delimiter">(</span>Memory<span class="Delimiter">,</span> Current_routine<span class="Delimiter">-&gt;</span>alloc<span class="Delimiter">,</span> curr_character<span class="Delimiter">);</span>
+    curr += tb_utf8_char_length<span class="Delimiter">(</span>raw_contents[curr]<span class="Delimiter">);</span>
+    ++Current_routine<span class="Delimiter">-&gt;</span>alloc<span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  <span class="Comment">// mu strings are not null-terminated in memory</span>
+  <span class="Identifier">return</span> result<span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="Comment">//: stash recognizes strings</span>
+
+<span class="Delimiter">:(scenario stash_string)</span>
+recipe main [
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new [abc]
+  stash [foo:]<span class="Delimiter">,</span> <span class="Constant">1</span>:address:shared:array:character
+]
+<span class="traceContains">+app: foo: abc</span>
+
+<span class="Delimiter">:(before &quot;End print Special-cases(reagent r, data)&quot;)</span>
+if <span class="Delimiter">(</span>is_mu_string<span class="Delimiter">(</span>r<span class="Delimiter">))</span> <span class="Delimiter">{</span>
+  assert<span class="Delimiter">(</span>scalar<span class="Delimiter">(</span>data<span class="Delimiter">));</span>
+  <span class="Identifier">return</span> read_mu_string<span class="Delimiter">(</span>data<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">))</span>+<span class="Constant">' '</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="Delimiter">:(scenario unicode_string)</span>
+recipe main [
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new [♠]
+  stash [foo:]<span class="Delimiter">,</span> <span class="Constant">1</span>:address:shared:array:character
+]
+<span class="traceContains">+app: foo: ♠</span>
+
+<span class="Delimiter">:(scenario stash_space_after_string)</span>
+recipe main [
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new [abc]
+  stash <span class="Constant">1</span>:address:shared:array:character<span class="Delimiter">,</span> [foo]
+]
+<span class="traceContains">+app: abc foo</span>
+
+<span class="Comment">//: Allocate more to routine when initializing a literal string</span>
+<span class="Delimiter">:(scenario new_string_overflow)</span>
+<span class="Special">% Initial_memory_per_routine = 2;</span>
+recipe main [
+  <span class="Constant">1</span>:address:shared:number/<span class="Special">raw &lt;- </span>new number:type
+  <span class="Constant">2</span>:address:shared:array:character/<span class="Special">raw &lt;- </span>new [a]  <span class="Comment"># not enough room in initial page, if you take the array size into account</span>
+]
+<span class="traceContains">+new: routine allocated memory from 1000 to 1002</span>
+<span class="traceContains">+new: routine allocated memory from 1002 to 1004</span>
+
+<span class="Comment">//: helpers</span>
+<span class="Delimiter">:(code)</span>
+long long int unicode_length<span class="Delimiter">(</span>const string&amp; s<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+  const char* in = s<span class="Delimiter">.</span>c_str<span class="Delimiter">();</span>
+  long long int result = <span class="Constant">0</span><span class="Delimiter">;</span>
+  long long int curr = <span class="Constant">0</span><span class="Delimiter">;</span>
+  while <span class="Delimiter">(</span>curr &lt; SIZE<span class="Delimiter">(</span>s<span class="Delimiter">))</span> <span class="Delimiter">{</span>  <span class="Comment">// carefully bounds-check on the string</span>
+    <span class="Comment">// before accessing its raw pointer</span>
+    ++result<span class="Delimiter">;</span>
+    curr += tb_utf8_char_length<span class="Delimiter">(</span>in[curr]<span class="Delimiter">);</span>
+  <span class="Delimiter">}</span>
+  <span class="Identifier">return</span> result<span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+string read_mu_string<span class="Delimiter">(</span>long long int address<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+  if <span class="Delimiter">(</span>address == <span class="Constant">0</span><span class="Delimiter">)</span> <span class="Identifier">return</span> <span class="Constant">&quot;&quot;</span><span class="Delimiter">;</span>
+  address++<span class="Delimiter">;</span>  <span class="Comment">// skip refcount</span>
+  long long int size = get_or_insert<span class="Delimiter">(</span>Memory<span class="Delimiter">,</span> address<span class="Delimiter">);</span>
+  if <span class="Delimiter">(</span>size == <span class="Constant">0</span><span class="Delimiter">)</span> <span class="Identifier">return</span> <span class="Constant">&quot;&quot;</span><span class="Delimiter">;</span>
+  ostringstream tmp<span class="Delimiter">;</span>
+  for <span class="Delimiter">(</span>long long int curr = address+<span class="Constant">1</span><span class="Delimiter">;</span> curr &lt;= address+size<span class="Delimiter">;</span> ++curr<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    tmp &lt;&lt; to_unicode<span class="Delimiter">(</span>static_cast&lt;uint32_t&gt;<span class="Delimiter">(</span>get_or_insert<span class="Delimiter">(</span>Memory<span class="Delimiter">,</span> curr<span class="Delimiter">)));</span>
+  <span class="Delimiter">}</span>
+  <span class="Identifier">return</span> tmp<span class="Delimiter">.</span>str<span class="Delimiter">();</span>
+<span class="Delimiter">}</span>
+
+bool is_mu_type_literal<span class="Delimiter">(</span>reagent r<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+<span class="CommentedCode">//?   if (!r.properties.empty())</span>
+<span class="CommentedCode">//?     dump_property(r.properties.at(0).second, cerr);</span>
+  <span class="Identifier">return</span> is_literal<span class="Delimiter">(</span>r<span class="Delimiter">)</span> &amp;&amp; !r<span class="Delimiter">.</span>properties<span class="Delimiter">.</span>empty<span class="Delimiter">()</span> &amp;&amp; r<span class="Delimiter">.</span>properties<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>second &amp;&amp; r<span class="Delimiter">.</span>properties<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>second<span class="Delimiter">-&gt;</span>value == <span class="Constant">&quot;type&quot;</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+</pre>
+</body>
+</html>
+<!-- vim: set foldmethod=manual : -->