Enable optimizer pipeline for DBC.

runtime/vm/intermediate_language.h

Index: runtime/vm/intermediate_language.h
diff --git a/runtime/vm/intermediate_language.h b/runtime/vm/intermediate_language.h
index a7f3d7f8c4c6f3006486a53c33cf2fe8b52411a3..931de101a191130df7e1f4d9641b4c6102a4f85e 100644
--- a/runtime/vm/intermediate_language.h
+++ b/runtime/vm/intermediate_language.h
@@ -8188,6 +8188,30 @@ class Environment : public ZoneAllocated {
   // from the copy.
   Environment* DeepCopy(Zone* zone, intptr_t length) const;
 
+#if defined(TARGET_ARCH_DBC)
+  // Return/ReturnTOS instruction drops incoming arguments so
+  // we have to drop outgoing arguments from the innermost environment.
+  // On all other architectures caller drops outgoing arguments itself
+  // hence the difference.
+  // Note: this method can only be used at the code generation stage because
+  // it mutates environment in unsafe way (e.g. does not update def-use
+  // chains).
+  void DropArguments(intptr_t argc) {

[Florian Schneider, 2016/05/19 13:21:40]

Maybe put only a declaration here, and put the definition into
intermediate_language_dbc.cc.

[Vyacheslav Egorov (Google), 2016/05/19 15:19:40]

Done.

+#if defined(DEBUG)
+    // Check that we are in the backend - register allocation has been run.
+    ASSERT(locations_ != NULL);
+
+    // Check that we are only dropping PushArgument instructions from the
+    // environment.
+    ASSERT(argc <= values_.length());
+    for (intptr_t i = 0; i < argc; i++) {
+      ASSERT(values_[values_.length() - i - 1]->definition()->IsPushArgument());
+    }
+#endif
+    values_.TruncateTo(values_.length() - argc);
+  }
+#endif
+
  private:
   friend class ShallowIterator;