Further improve and simplify IL for building constructor type arguments.

runtime/vm/intermediate_language_arm.cc

Index: runtime/vm/intermediate_language_arm.cc
===================================================================
--- runtime/vm/intermediate_language_arm.cc	(revision 22926)
+++ runtime/vm/intermediate_language_arm.cc	(working copy)
@@ -1610,27 +1610,26 @@
 
   // instantiator_reg is the instantiator type argument vector, i.e. an
   // AbstractTypeArguments object (or null).
-  if (!type_arguments().IsUninstantiatedIdentity() &&
-      !type_arguments().CanShareInstantiatorTypeArguments(
-          instantiator_class())) {
-    // If the instantiator is null and if the type argument vector
-    // instantiated from null becomes a vector of dynamic, then use null as
-    // the type arguments.
-    Label type_arguments_instantiated;
-    const intptr_t len = type_arguments().Length();
-    if (type_arguments().IsRawInstantiatedRaw(len)) {
-      __ CompareImmediate(instantiator_reg,
-                          reinterpret_cast<intptr_t>(Object::null()));
-      __ b(&type_arguments_instantiated, EQ);
-    }
-    // Instantiate non-null type arguments.
-    // In the non-factory case, we rely on the allocation stub to
-    // instantiate the type arguments.
-    __ LoadObject(result_reg, type_arguments());
-    // result_reg: uninstantiated type arguments.
-    __ Bind(&type_arguments_instantiated);
+  ASSERT(!type_arguments().IsUninstantiatedIdentity() &&
+         !type_arguments().CanShareInstantiatorTypeArguments(
+             instantiator_class()));
+  // If the instantiator is null and if the type argument vector
+  // instantiated from null becomes a vector of dynamic, then use null as
+  // the type arguments.
+  Label type_arguments_instantiated;
+  const intptr_t len = type_arguments().Length();
+  if (type_arguments().IsRawInstantiatedRaw(len)) {
+    __ CompareImmediate(instantiator_reg,
+                        reinterpret_cast<intptr_t>(Object::null()));
+    __ b(&type_arguments_instantiated, EQ);
   }
-  ASSERT(instantiator_reg == result_reg);
+  // Instantiate non-null type arguments.
+  // In the non-factory case, we rely on the allocation stub to
+  // instantiate the type arguments.
+  __ LoadObject(result_reg, type_arguments());
+  // result_reg: uninstantiated type arguments.
+  __ Bind(&type_arguments_instantiated);
+
   // result_reg: uninstantiated or instantiated type arguments.
 }
 
@@ -1654,29 +1653,24 @@
 
   // instantiator_reg is the instantiator AbstractTypeArguments object
   // (or null).
-  if (type_arguments().IsUninstantiatedIdentity() ||
-      type_arguments().CanShareInstantiatorTypeArguments(
-          instantiator_class())) {
-    // The instantiator was used in VisitExtractConstructorTypeArguments as the
+  ASSERT(!type_arguments().IsUninstantiatedIdentity() &&
+         !type_arguments().CanShareInstantiatorTypeArguments(
+             instantiator_class()));
+
+  // If the instantiator is null and if the type argument vector
+  // instantiated from null becomes a vector of dynamic, then use null as
+  // the type arguments and do not pass the instantiator.
+  const intptr_t len = type_arguments().Length();
+  if (type_arguments().IsRawInstantiatedRaw(len)) {
+    Label instantiator_not_null;
+    __ CompareImmediate(instantiator_reg,
+                        reinterpret_cast<intptr_t>(Object::null()));
+    __ b(&instantiator_not_null, NE);
+    // Null was used in VisitExtractConstructorTypeArguments as the
     // instantiated type arguments, no proper instantiator needed.
     __ LoadImmediate(instantiator_reg,

[Kevin Millikin (Google), 2013/05/21 11:06:05]

Yeah, this is kind of broken.

                      Smi::RawValue(StubCode::kNoInstantiator));
-  } else {
-    // If the instantiator is null and if the type argument vector
-    // instantiated from null becomes a vector of dynamic, then use null as
-    // the type arguments and do not pass the instantiator.
-    const intptr_t len = type_arguments().Length();
-    if (type_arguments().IsRawInstantiatedRaw(len)) {
-      Label instantiator_not_null;
-      __ CompareImmediate(instantiator_reg,
-                          reinterpret_cast<intptr_t>(Object::null()));
-      __ b(&instantiator_not_null, NE);
-      // Null was used in VisitExtractConstructorTypeArguments as the
-      // instantiated type arguments, no proper instantiator needed.
-      __ LoadImmediate(instantiator_reg,
-                       Smi::RawValue(StubCode::kNoInstantiator));
-      __ Bind(&instantiator_not_null);
-    }
+    __ Bind(&instantiator_not_null);
   }
   // instantiator_reg: instantiator or kNoInstantiator.
 }