[vm/compiler] Streamline code generated for empty list literals

Previously, empty list literals were generated as

  List<E>._fromLiteral(const [])

List._fromLiteral checks if the argument is an empty list and
calls _GrowableList<E>(0) in such case.
If List._fromLiteral is not inlined, this adds an unnecessary overhead.

Now empty list literals are generated more directly as

  _GrowableList<E>(0)

Havlak +15.58% in AOT mode with null safety.

Change-Id: I6723e1e912cd0bbcbbb622f928d912c554217e5e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/159201
Commit-Queue: Alexander Markov <[email protected]>
Reviewed-by: Vyacheslav Egorov <[email protected]>
Reviewed-by: Régis Crelier <[email protected]>

Author: alexmarkov

runtime/vm/compiler/frontend/kernel_binary_flowgraph.cc

@@ -3780,24 +3780,30 @@ Fragment StreamingFlowGraphBuilder::BuildListLiteral(TokenPosition* p) {
 
   // The type argument for the factory call.
   Fragment instructions = TranslateInstantiatedTypeArguments(type_arguments);
+
+  if (length == 0) {
+    instructions += IntConstant(0);
+    instructions += StaticCall(
+        position,
+        Function::ZoneHandle(Z, I->object_store()->growable_list_factory()), 2,
+        ICData::kStatic);
+    return instructions;
+  }
+
   LocalVariable* type = MakeTemporary();
+  instructions += LoadLocal(type);
 
+  // The type arguments for CreateArray.
   instructions += LoadLocal(type);
-  if (length == 0) {
-    instructions += Constant(Object::empty_array());
-  } else {
-    // The type arguments for CreateArray.
-    instructions += LoadLocal(type);
-    instructions += IntConstant(length);
-    instructions += CreateArray();
+  instructions += IntConstant(length);
+  instructions += CreateArray();
 
-    LocalVariable* array = MakeTemporary();
-    for (intptr_t i = 0; i < length; ++i) {
-      instructions += LoadLocal(array);
-      instructions += IntConstant(i);
-      instructions += BuildExpression();  // read ith expression.
-      instructions += StoreIndexed(kArrayCid);
-    }
+  LocalVariable* array = MakeTemporary();
+  for (intptr_t i = 0; i < length; ++i) {
+    instructions += LoadLocal(array);
+    instructions += IntConstant(i);
+    instructions += BuildExpression();  // read ith expression.
+    instructions += StoreIndexed(kArrayCid);
   }
 
   const Class& factory_class =