Revert r10475.

runtime/vm/flow_graph_optimizer.cc

Index: runtime/vm/flow_graph_optimizer.cc
===================================================================
--- runtime/vm/flow_graph_optimizer.cc	(revision 10475)
+++ runtime/vm/flow_graph_optimizer.cc	(working copy)
@@ -549,101 +549,27 @@
 void FlowGraphTypePropagator::VisitAssertAssignable(AssertAssignableComp* comp,
                                                     BindInstr* instr) {
   if (FLAG_eliminate_type_checks &&
-      !comp->IsEliminated() &&
+      (comp->value() != NULL) &&
       !comp->dst_type().IsMalformed() &&
-      comp->value()->CompileTypeIsMoreSpecificThan(comp->dst_type())) {
-    comp->Eliminate();
+      comp->value()->StaticTypeIsMoreSpecificThan(comp->dst_type())) {
+    // TODO(regis): Eliminate type check by removing comp node from graph.
     if (FLAG_trace_type_check_elimination) {
       FlowGraphPrinter::PrintTypeCheck(parsed_function(),
                                        comp->token_pos(),
                                        comp->value(),
                                        comp->dst_type(),
                                        comp->dst_name(),
-                                       comp->IsEliminated());
+                                       /*eliminated*/ true);
     }
   }
 }
 
 
-void FlowGraphTypePropagator::VisitGraphEntry(GraphEntryInstr* graph_entry) {
-  if (graph_entry->start_env() == NULL) {
-    return;
-  }
-  // Visit incoming parameters.
-  for (intptr_t i = 0; i < graph_entry->start_env()->values().length(); i++) {
-    Value* val = graph_entry->start_env()->values()[i];
-    if (val->IsUse()) {
-      ParameterInstr* param = val->AsUse()->definition()->AsParameter();
-      if (param != NULL) {
-        VisitParameter(param);
-      }
-    }
-  }
+void FlowGraphTypePropagator::VisitBind(BindInstr* instr) {
+  instr->computation()->Accept(this, instr);
 }
 
 
-void FlowGraphTypePropagator::VisitJoinEntry(JoinEntryInstr* join_entry) {
-  if (join_entry->phis() != NULL) {
-    for (intptr_t i = 0; i < join_entry->phis()->length(); ++i) {
-      PhiInstr* phi = (*join_entry->phis())[i];
-      if (phi != NULL) {
-        VisitPhi(phi);
-      }
-    }
-  }
-}
-
-
-void FlowGraphTypePropagator::VisitBind(BindInstr* bind) {
-  // No need to propagate the input types of the bound computation, as long as
-  // PhiInstr's are handled as part of JoinEntryInstr.
-  // Visit computation and possibly eliminate type check.
-  bind->computation()->Accept(this, bind);
-  // Cache propagated computation type.
-  AbstractType& type = AbstractType::Handle(bind->computation()->CompileType());
-  bool changed = bind->SetPropagatedType(type);
-  if (changed) {
-    still_changing_ = true;
-  }
-}
-
-
-void FlowGraphTypePropagator::VisitPhi(PhiInstr* phi) {
-  // We could set the propagated type of the phi to the least upper bound of its
-  // input propagated types. However, keeping all propagated types allows us to
-  // optimize method dispatch.
-  // TODO(regis): Support a set of propagated types. For now, we compute the
-  // least specific of the input propagated types.
-  AbstractType& type = AbstractType::Handle(phi->LeastSpecificInputType());
-  bool changed = phi->SetPropagatedType(type);
-  if (changed) {
-    still_changing_ = true;
-  }
-}
-
-
-void FlowGraphTypePropagator::VisitParameter(ParameterInstr* param) {
-  // TODO(regis): Once we inline functions, the propagated type of the formal
-  // parameter will reflect the compile type of the passed-in argument.
-  // For now, we do not known anything about this type and therefore set it to
-  // the DynamicType.
-  bool changed = param->SetPropagatedType(Type::Handle(Type::DynamicType()));
-  if (changed) {
-    still_changing_ = true;
-  }
-}
-
-
-void FlowGraphTypePropagator::PropagateTypes() {
-  // TODO(regis): Is there a way to make this more efficient, e.g. by visiting
-  // only blocks depending on blocks that have changed and not the whole graph.
-  do {
-    still_changing_ = false;
-    VisitBlocks();
-  } while (still_changing_);
-}
-
-
 void FlowGraphAnalyzer::Analyze() {
   is_leaf_ = true;
   for (intptr_t i = 0; i < blocks_.length(); ++i) {
@@ -658,4 +584,9 @@
   }
 }
 
+
+void FlowGraphTypePropagator::PropagateTypes() {
+  VisitBlocks();
+}
+
 }  // namespace dart