- Dump Smi objects into the heap profile.

runtime/vm/heap_profiler.cc

Index: runtime/vm/heap_profiler.cc
===================================================================
--- runtime/vm/heap_profiler.cc	(revision 16999)
+++ runtime/vm/heap_profiler.cc	(working copy)
@@ -124,6 +124,11 @@
 
 
 HeapProfiler::~HeapProfiler() {
+  for (std::set<const RawSmi*>::iterator it = smi_table_.begin();

[cshapiro, 2013/01/12 02:52:26]

You might consider using this idiom...

  for_each(smi_table_.begin(), 
           smi_table_.end(),
           bind1st(mem_fun(&HeapProfiler::WriteSmiDump), this)

+       it != smi_table_.end();
+       ++it) {
+    WriteSmiDump(*it);
+  }
   delete heap_dump_record_;
 }
 
@@ -566,7 +571,28 @@
   }
 }
 
+// INSTANCE DUMP - 0x21

[cshapiro, 2013/01/12 02:52:26]

We probably do not need to repeat this documentation.

My preference would be to rename this method "WriteSmiInstanceDump" and move it
just below the WriteInstanceDump method.  This is the pattern I followed for the
"Fake" methods I just added (WriteFakeInstanceDump, etc.).

[Ivan Posva, 2013/01/14 23:38:42]

Done.

+//
+// Format:
+//  ID - object ID
+//  u4 - stack trace serial number
+//  ID - class object ID
+//  u4 - number of bytes that follow
+//  [value]* - instance field values (this class, followed by super class, etc)
+void HeapProfiler::WriteSmiDump(const RawSmi* raw_smi) {
+  ASSERT(!raw_smi->IsHeapObject());
+  SubRecord sub(kInstanceDump, this);
+  // object ID
+  sub.WriteObjectId(raw_smi);

[siva, 2013/01/14 23:50:13]

Since we are writing out smi values as an object id can this potentially collide
with other object ids that we emit out (e.g a class id)

[Ivan Posva, 2013/01/14 23:53:38]

IDs from the heap profiler dump perspective are the tagged addresses, so we
never get into the VM internal Cid and Smi conflict.

[cshapiro, 2013/01/14 23:55:22]

It should not.  We use an object's address as its it, tag included.  I use some
magic small odd values (small enough that they would fit on page 0) to designate
non-existent classes to keep this convention consistent even when real heap
addresses are unused.

+  // stack trace serial number
+  sub.Write32(0);
+  // class object ID
+  sub.WriteObjectId(Isolate::Current()->class_table()->At(kSmiCid));
+  // number of bytes that follow
+  sub.Write32(0);
+}
 
+
 // INSTANCE DUMP - 0x21
 //
 // Format:
@@ -576,6 +602,7 @@
 //  u4 - number of bytes that follow
 //  [value]* - instance field values (this class, followed by super class, etc)
 void HeapProfiler::WriteInstanceDump(const RawObject* raw_obj) {
+  ASSERT(raw_obj->IsHeapObject());
   SubRecord sub(kInstanceDump, this);
   // object ID
   sub.WriteObjectId(raw_obj);