4179 - experiment: rip out memory reclamation

I have a plan for a way to avoid use-after-free errors without all the
overheads of maintaining refcounts. Has the nice side-effect of
requiring manual memory management. The Mu way is to leak memory by
default and build tools to help decide when and where to expend effort
plugging memory leaks. Arguably programs should be distributed with
summaries of their resource use characteristics.

Eliminating refcount maintenance reduces time to run tests by 30% for
`mu edit`:

              this commit                 parent
  mu test:         3.9s                        4.5s
  mu test edit:  2:38                        3:48

Open questions:
  - making reclamation easier; some sort of support for destructors
  - reclaiming local scopes (which are allocated on the heap)
    - should we support automatically reclaiming allocations inside them?

1 files changed, 0 insertions, 19 deletions

diff --git a/069hash.cc b/069hash.cc
index 8334e80c..4400c1e8 100644
--- a/069hash.cc
+++ b/069hash.cc
@@ -57,10 +57,6 @@ size_t hash_mu_address(size_t h, reagent& r) {
   if (r.value == 0) return 0;
   trace("mem") << "location " << r.value << " is " << no_scientific(get_or_insert(Memory, r.value)) << end();
   r.set_value(get_or_insert(Memory, r.value));
-  if (r.value != 0) {
-    trace("mem") << "skipping refcount at " << r.value << end();
-    r.set_value(r.value+1);  // skip refcount
-  }
   drop_from_type(r, "address");
   return hash(h, r);
 }
@@ -230,21 +226,6 @@ def main [
 # different addresses hash to the same result as long as the values the point to do so
 +mem: storing 1 in location 5
 
-:(scenario hash_ignores_address_refcount)
-def main [
-  1:&:num <- new number:type
-  *1:&:num <- copy 34
-  2:num <- hash 1:&:num
-  return-unless 2:num
-  # increment refcount
-  3:&:num <- copy 1:&:num
-  4:num <- hash 3:&:num
-  return-unless 4:num
-  5:bool <- equal 2:num, 4:num
-]
-# hash doesn't change when refcount changes
-+mem: storing 1 in location 5
-
 :(scenario hash_container_depends_only_on_elements)
 container foo [
   x:num