Implement class id checks as a separate instruction and add a local CSE optimization pass.

runtime/vm/intermediate_language.cc

Index: runtime/vm/intermediate_language.cc
===================================================================
--- runtime/vm/intermediate_language.cc	(revision 10885)
+++ runtime/vm/intermediate_language.cc	(working copy)
@@ -21,6 +21,46 @@
 
 DECLARE_FLAG(bool, enable_type_checks);
 
+
+intptr_t Computation::Hashcode() const {
+  intptr_t result = computation_kind();
+  for (intptr_t i = 0; i < InputCount(); ++i) {
+    UseVal* val = InputAt(i)->AsUse();
+    intptr_t j = val != NULL
+        ? val->definition()->ssa_temp_index()
+        : -1;
+    result = result * 31 + j;
+  }
+  return result;
+}
+
+
+bool Computation::Equals(Computation* other) const {
+  if (computation_kind() != other->computation_kind()) return false;
+  for (intptr_t i = 0; i < InputCount(); ++i) {
+    if (!InputAt(i)->Equals(other->InputAt(i))) return false;
+  }
+  return AttributesEqual(other);
+}
+
+
+bool CheckClassComp::AttributesEqual(Computation* other) const {
+  CheckClassComp* other_check = other->AsCheckClass();
+  if (other_check == NULL) return false;
+  if (ic_data()->NumberOfChecks() != other->ic_data()->NumberOfChecks()) {
+    return false;
+  }
+  for (intptr_t i = 0; i < ic_data()->NumberOfChecks(); ++i) {
+    // TODO(fschneider): Make sure ic_data are sorted to hit more cases.
+    if (ic_data()->GetReceiverClassIdAt(i) !=
+        other->ic_data()->GetReceiverClassIdAt(i)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+
 UseVal::UseVal(Definition* definition)
     : definition_(definition), next_use_(NULL), previous_use_(NULL) {
   AddToUseList();
@@ -177,6 +217,16 @@
 }
 
 
+void BindInstr::InsertBefore(BindInstr* next) {
+  ASSERT(previous_ == NULL);
+  ASSERT(next_ == NULL);
+  next_ = next;
+  previous_ = next->previous_;
+  next->previous_ = this;
+  previous_->next_ = this;
+}
+
+
 void ForwardInstructionIterator::RemoveCurrentFromGraph() {
   current_ = current_->RemoveFromGraph(true);  // Set current_ to previous.
 }
@@ -965,6 +1015,11 @@
 }
 
 
+RawAbstractType* CheckClassComp::CompileType() const {
+  return AbstractType::null();
+}
+
+
 // Shared code generation methods (EmitNativeCode, MakeLocationSummary, and
 // PrepareEntry). Only assembly code that can be shared across all architectures
 // can be used. Machine specific register allocation and code generation