Introduce nested deoptimization environments.

runtime/vm/flow_graph_allocator.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_allocator.h"
 
 #include "vm/bit_vector.h"
 #include "vm/intermediate_language.h"
 #include "vm/il_printer.h"
 #include "vm/flow_graph.h"
@@ skipping 77 matching lines @@
 void FlowGraphAllocator::EliminateEnvironmentUses() {
   ConstantInstr* constant_null =
       postorder_.Last()->AsGraphEntry()->constant_null();
   for (intptr_t i = 0; i < block_order_.length(); ++i) {
     BlockEntryInstr* block = block_order_[i];
     if (block->IsJoinEntry()) block->AsJoinEntry()->RemoveDeadPhis();
     for (ForwardInstructionIterator it(block); !it.Done(); it.Advance()) {
       Instruction* current = it.Current();
       if (current->CanDeoptimize()) {
         ASSERT(current->env() != NULL);
-        GrowableArray<Value*>* values = current->env()->values_ptr();
-        for (intptr_t i = 0; i < values->length(); i++) {
-          Value* use = (*values)[i];
+        for (Environment::DeepIterator it(current->env());
+             !it.Done();
+             it.Advance()) {
+          Value* use = it.CurrentValue();
           Definition* def = use->definition();
           PushArgumentInstr* push_argument = def->AsPushArgument();
           if ((push_argument != NULL) && push_argument->WasEliminated()) {
-            (*values)[i] = push_argument->value()->Copy();
+            it.SetCurrentValue(push_argument->value()->Copy());
             continue;
           }
 
           PhiInstr* phi = def->AsPhi();
           if ((phi != NULL) && !phi->is_alive()) {
-            (*values)[i] = new Value(constant_null);
+            it.SetCurrentValue(new Value(constant_null));
             continue;
           }
         }
       } else {
         current->set_env(NULL);
       }
     }
   }
 }
 
@@ skipping 17 matching lines @@
         live_in->Remove(current_def->ssa_temp_index());
       }
 
       // Handle uses.
       for (intptr_t j = 0; j < current->InputCount(); j++) {
         Value* input = current->InputAt(j);
         const intptr_t use = input->definition()->ssa_temp_index();
         live_in->Add(use);
       }
 
-      // Add uses from the deoptimization environment.
+      // Add non-argument uses from the deoptimization environment (pushed
+      // arguments are not allocated by the register allocator).
       if (current->env() != NULL) {
-        const GrowableArray<Value*>& values = current->env()->values();
-        for (intptr_t j = 0; j < values.length(); j++) {
-          Value* value = values[j];
+        for (intptr_t i = 0; i < current->env()->Length(); ++i) {
+          Value* value = current->env()->ValueAt(i);
           if (!value->definition()->IsPushArgument()) {
             live_in->Add(value->definition()->ssa_temp_index());
           }
         }
       }
     }
 
     // Handle phis.
     if (block->IsJoinEntry()) {
       JoinEntryInstr* join = block->AsJoinEntry();
@@ skipping 15 matching lines @@
               live_in_[pred->postorder_number()]->Add(use);
             }
           }
         }
       }
     }
   }
 
   // Process incoming parameters.
   GraphEntryInstr* graph_entry = postorder_.Last()->AsGraphEntry();
-  for (intptr_t i = 0; i < graph_entry->start_env()->values().length(); i++) {
-    Value* val = graph_entry->start_env()->values()[i];
+  for (intptr_t i = 0; i < graph_entry->start_env()->Length(); i++) {
+    Value* val = graph_entry->start_env()->ValueAt(i);
     intptr_t vreg = val->definition()->ssa_temp_index();
     kill_[graph_entry->postorder_number()]->Add(vreg);
     live_in_[graph_entry->postorder_number()]->Remove(vreg);
   }
 
   // Process global constants.
   intptr_t vreg = graph_entry->constant_null()->ssa_temp_index();
   kill_[graph_entry->postorder_number()]->Add(vreg);
   live_in_[graph_entry->postorder_number()]->Remove(vreg);
 
@@ skipping 312 matching lines @@
       }
       current = current->previous();
     }
 
     ConnectIncomingPhiMoves(block);
   }
 
   // Process incoming parameters.  Do this after all other instructions so
   // that safepoints for all calls have already been found.
   GraphEntryInstr* graph_entry = postorder_.Last()->AsGraphEntry();
-  for (intptr_t i = 0; i < graph_entry->start_env()->values().length(); i++) {
-    Value* val = graph_entry->start_env()->values()[i];
+  for (intptr_t i = 0; i < graph_entry->start_env()->Length(); i++) {
+    Value* val = graph_entry->start_env()->ValueAt(i);
     ParameterInstr* param = val->definition()->AsParameter();
     if (param == NULL) continue;
 
     // Handle the parameters specially.  They are spilled on entry.
     LiveRange* range = GetLiveRange(param->ssa_temp_index());
     range->AddUseInterval(graph_entry->start_pos(), graph_entry->end_pos());
     range->DefineAt(graph_entry->start_pos());
 
     // Assert that copied and non-copied parameters are mutually exclusive.
     // This might change in the future and, if so, the index will be wrong.
@@ skipping 207 matching lines @@
   Environment* env = current->env();
 
   // Any value mentioned in the deoptimization environment should survive
   // until the end of instruction but it does not need to be in the register.
   // Expected shape of live range:
   //
   //                 i  i'
   //      value    -----*
   //
 
-  const GrowableArray<Value*>& values = env->values();
-  if (values.length() == 0) return;
+  if (env->Length() == 0) return;
 
   const intptr_t block_start_pos = block->start_pos();
   const intptr_t use_pos = current->lifetime_position() + 1;
 
   Location* locations =
-      Isolate::Current()->current_zone()->Alloc<Location>(values.length());
+      Isolate::Current()->current_zone()->Alloc<Location>(env->Length());
 
-  for (intptr_t i = 0; i < values.length(); ++i) {
-    Value* value = values[i];
+  for (intptr_t i = 0; i < env->Length(); ++i) {
+    Value* value = env->ValueAt(i);
     locations[i] = Location::Any();
     Definition* def = value->definition();
 
     if (def->IsPushArgument()) {
       // Frame size is unknown until after allocation.
       locations[i] = Location::NoLocation();
       continue;
     }
 
     ConstantInstr* constant = def->AsConstant();
@@ skipping 1411 matching lines @@
     OS::Print("-- [after ssa allocator] ir [%s] -------------\n",
               function.ToFullyQualifiedCString());
     FlowGraphPrinter printer(flow_graph_, true);
     printer.PrintBlocks();
     OS::Print("----------------------------------------------\n");
   }
 }
 
 
 }  // namespace dart