Replace start_env with initial_definitions in GraphEntryInstr.

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 169 matching lines @@
             const intptr_t use = val->definition()->ssa_temp_index();
             if (!kill_[pred->postorder_number()]->Contains(use)) {
               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()->Length(); i++) {
-    Value* val = graph_entry->start_env()->ValueAt(i);
-    intptr_t vreg = val->definition()->ssa_temp_index();
+  // Process initial definitions, ie, constants and incoming parameters.
+  GraphEntryInstr* graph_entry = flow_graph_.graph_entry();
+  for (intptr_t i = 0; i < graph_entry->initial_definitions()->length(); i++) {
+    intptr_t vreg = (*graph_entry->initial_definitions())[i]->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);
-
   // Update initial live_in sets to match live_out sets. Has to be
   // done in a separate path because of backwards branches.
   for (intptr_t i = 0; i < block_count; i++) {
     UpdateLiveIn(*postorder_[i]);
   }
 }
 
 
 bool FlowGraphAllocator::UpdateLiveOut(const BlockEntryInstr& instr) {
   BitVector* live_out = live_out_[instr.postorder_number()];
@@ skipping 299 matching lines @@
       // Skip parallel moves that we insert while processing instructions.
       if (!current->IsParallelMove()) {
         ProcessOneInstruction(block, current);
       }
       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()->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());
+  // Process incoming parameters and constants.  Do this after all other
+  // instructions so that safepoints for all calls have already been found.
+  GraphEntryInstr* graph_entry = flow_graph_.graph_entry();
+  for (intptr_t i = 0; i < graph_entry->initial_definitions()->length(); i++) {
+    Definition* defn = (*graph_entry->initial_definitions())[i];
+    LiveRange* range = GetLiveRange(defn->ssa_temp_index());
     range->AddUseInterval(graph_entry->start_pos(), graph_entry->end_pos());
     range->DefineAt(graph_entry->start_pos());
+    if (defn->IsParameter()) {
+      ParameterInstr* param = defn->AsParameter();
+      // Assert that copied and non-copied parameters are mutually exclusive.
+      // This might change in the future and, if so, the index will be wrong.
+      ASSERT((flow_graph_.num_copied_params() == 0) ||
+             (flow_graph_.num_non_copied_params() == 0));
+      // Slot index for the leftmost copied parameter is 0.
+      intptr_t slot_index = param->index();
+      // Slot index for the rightmost fixed parameter is -1.
+      slot_index -= flow_graph_.num_non_copied_params();
 
-    // Assert that copied and non-copied parameters are mutually exclusive.
-    // This might change in the future and, if so, the index will be wrong.
-    ASSERT((flow_graph_.num_copied_params() == 0) ||
-           (flow_graph_.num_non_copied_params() == 0));
-    // Slot index for the leftmost copied parameter is 0.
-    intptr_t slot_index = param->index();
-    // Slot index for the rightmost fixed parameter is -1.
-    slot_index -= flow_graph_.num_non_copied_params();
-
-    range->set_assigned_location(Location::StackSlot(slot_index));
-    range->set_spill_slot(Location::StackSlot(slot_index));
-    if (flow_graph_.num_copied_params() > 0) {
-      ASSERT(spill_slots_.length() == slot_index);
-      spill_slots_.Add(range->End());
+      range->set_assigned_location(Location::StackSlot(slot_index));
+      range->set_spill_slot(Location::StackSlot(slot_index));
+      if (flow_graph_.num_copied_params() > 0) {
+        ASSERT(spill_slots_.length() == slot_index);
+        spill_slots_.Add(range->End());
+      }
+      AssignSafepoints(range);
+    } else {
+      ConstantInstr* constant = defn->AsConstant();
+      ASSERT(constant != NULL);
+      range->set_assigned_location(Location::Constant(constant->value()));
+      range->set_spill_slot(Location::Constant(constant->value()));
     }
-
-    AssignSafepoints(range);
-
     range->finger()->Initialize(range);
     UsePosition* use =
         range->finger()->FirstRegisterBeneficialUse(graph_entry->start_pos());
     if (use != NULL) {
       LiveRange* tail =
           SplitBetween(range, graph_entry->start_pos(), use->pos());
-      // All incoming parameters are tagged.
+      // Parameters and constants are tagged, so allocated to CPU registers.
       CompleteRange(tail, Location::kRegister);
     }
     ConvertAllUses(range);
-    if (flow_graph_.num_copied_params() > 0) {
+
+    if (defn->IsParameter() && flow_graph_.num_copied_params() > 0) {
       MarkAsObjectAtSafepoints(range);
     }
   }
-
-  // Process global constants.
-  ConstantInstr* null_defn = graph_entry->constant_null();
-  LiveRange* range = GetLiveRange(null_defn->ssa_temp_index());
-  range->AddUseInterval(graph_entry->start_pos(), graph_entry->end_pos());
-  range->DefineAt(graph_entry->start_pos());
-  range->set_assigned_location(Location::Constant(null_defn->value()));
-  range->set_spill_slot(Location::Constant(null_defn->value()));
-  range->finger()->Initialize(range);
-  UsePosition* use =
-      range->finger()->FirstRegisterBeneficialUse(graph_entry->start_pos());
-  if (use != NULL) {
-    LiveRange* tail = SplitBetween(range, graph_entry->start_pos(), use->pos());
-    CompleteRange(tail, Location::kRegister);
-  }
-  ConvertAllUses(range);
 }
 
 
 static Location::Kind RegisterKindFromPolicy(Location loc) {
   if (loc.policy() == Location::kRequiresXmmRegister) {
     return Location::kXmmRegister;
   } else {
     return Location::kRegister;
   }
 }
@@ skipping 1620 matching lines @@
     OS::Print("-- [after ssa allocator] ir [%s] -------------\n",
               function.ToFullyQualifiedCString());
     FlowGraphPrinter printer(flow_graph_, true);
     printer.PrintBlocks();
     OS::Print("----------------------------------------------\n");
   }
 }
 
 
 }  // namespace dart