diff --git a/src/IceTimerTree.cpp b/src/IceTimerTree.cpp
new file mode 100644
index 0000000..4bdb80a
--- /dev/null
+++ b/src/IceTimerTree.cpp
@@ -0,0 +1,142 @@
+//===- subzero/src/IceTimerTree.cpp - Pass timer defs ---------------------===//
+//
+//                        The Subzero Code Generator
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the TimerTree class, which tracks flat and
+// cumulative execution time collection of call chains.
+//
+//===----------------------------------------------------------------------===//
+
+#include "IceDefs.h"
+#include "IceTimerTree.h"
+
+namespace Ice {
+
+std::vector<IceString> TimerStack::IDs;
+
+TimerStack::TimerStack(const IceString &TopLevelName)
+    : FirstTimestamp(timestamp()), LastTimestamp(FirstTimestamp),
+      StateChangeCount(0), StackTop(0) {
+  Nodes.resize(1); // Reserve Nodes[0] for the root node.
+  push(getTimerID(TopLevelName));
+}
+
+// Returns the unique timer ID for the given Name, creating a new ID
+// if needed.  For performance reasons, it's best to make only one
+// call per Name and cache the result, e.g. via a static initializer.
+TimerIdT TimerStack::getTimerID(const IceString &Name) {
+  TimerIdT Size = IDs.size();
+  for (TimerIdT i = 0; i < Size; ++i) {
+    if (IDs[i] == Name)
+      return i;
+  }
+  IDs.push_back(Name);
+  return Size;
+}
+
+// Pushes a new marker onto the timer stack.
+void TimerStack::push(TimerIdT ID) {
+  update();
+  if (Nodes[StackTop].Children.size() <= ID)
+    Nodes[StackTop].Children.resize(ID + 1);
+  if (Nodes[StackTop].Children[ID] == 0) {
+    TTindex Size = Nodes.size();
+    Nodes[StackTop].Children[ID] = Size;
+    Nodes.resize(Size + 1);
+    Nodes[Size].Parent = StackTop;
+    Nodes[Size].Interior = ID;
+  }
+  StackTop = Nodes[StackTop].Children[ID];
+}
+
+// Pop the top marker from the timer stack.  Validates via assert()
+// that the expected marker is popped.
+void TimerStack::pop(TimerIdT ID) {
+  update();
+  assert(StackTop);
+  assert(Nodes[StackTop].Parent < StackTop);
+  // Verify that the expected ID is being popped.
+  assert(Nodes[StackTop].Interior == ID);
+  (void)ID;
+  // Verify that the parent's child points to the current stack top.
+  assert(Nodes[Nodes[StackTop].Parent].Children[ID] == StackTop);
+  StackTop = Nodes[StackTop].Parent;
+}
+
+// At a state change (e.g. push or pop), updates the flat and
+// cumulative timings for everything on the timer stack.
+void TimerStack::update() {
+  ++StateChangeCount;
+  // Whenever the stack is about to change, we grab the time delta
+  // since the last change and add it to all active cumulative
+  // elements and to the flat element for the top of the stack.
+  double Current = timestamp();
+  double Delta = Current - LastTimestamp;
+  LastTimestamp = Current;
+  if (StackTop) {
+    TimerIdT Leaf = Nodes[StackTop].Interior;
+    if (Leaf >= LeafTimes.size())
+      LeafTimes.resize(Leaf + 1);
+    LeafTimes[Leaf] += Delta;
+  }
+  TTindex Prefix = StackTop;
+  while (Prefix) {
+    Nodes[Prefix].Time += Delta;
+    TTindex Next = Nodes[Prefix].Parent;
+    assert(Next < Prefix);
+    Prefix = Next;
+  }
+}
+
+namespace {
+
+typedef std::multimap<double, IceString> DumpMapType;
+
+// Dump the Map items in reverse order of their time contribution.
+void dumpHelper(Ostream &Str, const DumpMapType &Map, double TotalTime) {
+  for (DumpMapType::const_reverse_iterator I = Map.rbegin(), E = Map.rend();
+       I != E; ++I) {
+    char buf[80];
+    snprintf(buf, llvm::array_lengthof(buf), "  %10.6f (%4.1f%%): ", I->first,
+             I->first * 100 / TotalTime);
+    Str << buf << I->second << "\n";
+  }
+}
+
+} // end of anonymous namespace
+
+void TimerStack::dump(Ostream &Str) {
+  update();
+  double TotalTime = LastTimestamp - FirstTimestamp;
+  assert(TotalTime);
+  Str << "Cumulative function times:\n";
+  DumpMapType CumulativeMap;
+  for (TTindex i = 1; i < Nodes.size(); ++i) {
+    TTindex Prefix = i;
+    IceString Suffix = "";
+    while (Prefix) {
+      if (Suffix.empty())
+        Suffix = IDs[Nodes[Prefix].Interior];
+      else
+        Suffix = IDs[Nodes[Prefix].Interior] + "." + Suffix;
+      assert(Nodes[Prefix].Parent < Prefix);
+      Prefix = Nodes[Prefix].Parent;
+    }
+    CumulativeMap.insert(std::make_pair(Nodes[i].Time, Suffix));
+  }
+  dumpHelper(Str, CumulativeMap, TotalTime);
+  Str << "Flat function times:\n";
+  DumpMapType FlatMap;
+  for (TimerIdT i = 0; i < LeafTimes.size(); ++i) {
+    FlatMap.insert(std::make_pair(LeafTimes[i], IDs[i]));
+  }
+  dumpHelper(Str, FlatMap, TotalTime);
+  Str << "Number of timer updates: " << StateChangeCount << "\n";
+}
+
+} // end of namespace Ice