RemoveFromGraph on definitions asserts empty use lists.

runtime/vm/flow_graph_optimizer.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/flow_graph_optimizer.h"
 
 #include "vm/flow_graph_builder.h"
 #include "vm/il_printer.h"
 #include "vm/object_store.h"
 #include "vm/parser.h"
@@ skipping 128 matching lines @@
 
 static bool HasOnlyTwoDouble(const ICData& ic_data) {
   return (ic_data.NumberOfChecks() == 1) &&
       ICDataHasReceiverArgumentClassIds(ic_data, kDoubleCid, kDoubleCid);
 }
 
 
 static void RemovePushArguments(InstanceCallComp* comp) {
   // Remove original push arguments.
   for (intptr_t i = 0; i < comp->ArgumentCount(); ++i) {
-    comp->ArgumentAt(i)->RemoveFromGraph();
+    PushArgumentInstr* push = comp->ArgumentAt(i);
+    // TODO(zerny): Currently the register allocator replaces unused pushes with
+    // their definitions. To do so here, we need first to link uses to their
+    // instructions and input index. Here push->ReplaceUsesWith requires that
+    // push->value() is a UseVal.
+    // (See FlowGraphAllocator::EliminateEnvironmentUses).
+    push->set_use_list(NULL);
+    push->RemoveFromGraph();
   }
 }
 
 
 bool FlowGraphOptimizer::TryReplaceWithBinaryOp(BindInstr* instr,
                                                 InstanceCallComp* comp,
                                                 Token::Kind op_kind) {
   BinaryOpComp::OperandsType operands_type = BinaryOpComp::kDynamicOperands;
   ASSERT(comp->HasICData());
   const ICData& ic_data = *comp->ic_data();
@@ skipping 558 matching lines @@
       LocationSummary* locs = it.Current()->locs();
       if ((locs != NULL) && locs->contains_call()) {
         is_leaf_ = false;
         return;
       }
     }
   }
 }
 
 }  // namespace dart