Basic support for LICM of fully invariant loads.

runtime/vm/flow_graph.h

 // Copyright (c) 2013, 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.
 
 #ifndef VM_FLOW_GRAPH_H_
 #define VM_FLOW_GRAPH_H_
 
 #include "vm/growable_array.h"
 #include "vm/intermediate_language.h"
 #include "vm/parser.h"
@@ skipping 110 matching lines @@
                     Definition::UseKind use_kind);
   void InsertAfter(Instruction* prev,
                    Instruction* instr,
                    Environment* env,
                    Definition::UseKind use_kind);
 
   // Operations on the flow graph.
   void ComputeSSA(intptr_t next_virtual_register_number,
                   ZoneGrowableArray<Definition*>* inlining_parameters);
 
-  // Finds natural loops in the flow graph and attaches a list of loop
-  // body blocks for each loop header.
-  void ComputeLoops(GrowableArray<BlockEntryInstr*>* loop_headers);
-
   // TODO(zerny): Once the SSA is feature complete this should be removed.
   void Bailout(const char* reason) const;
 
 #ifdef DEBUG
   // Verification methods for debugging.
   bool VerifyUseLists();
 #endif  // DEBUG
 
   void DiscoverBlocks();
 
@@ skipping 15 matching lines @@
 
   // Returns true if every Goto in the graph is expected to have a
   // deoptimization environment and can be used as deoptimization target
   // for hoisted instructions.
   bool is_licm_allowed() const { return licm_allowed_; }
 
   // Stop preserving environments on Goto instructions. LICM is not allowed
   // after this point.
   void disallow_licm() { licm_allowed_ = false; }
 
+  const ZoneGrowableArray<BlockEntryInstr*>& loop_headers() {
+    if (loop_headers_ == NULL) {
+      loop_headers_ = ComputeLoops();
+    }
+    return *loop_headers_;
+  }
+
+  // Per loop header invariant loads sets. Each set contains load id for
+  // those loads that are not affected by anything in the loop and can be
+  // hoisted out. Sets are computed by LoadOptimizer.
+  ZoneGrowableArray<BitVector*>* loop_invariant_loads() const {
+    return loop_invariant_loads_;
+  }
+  void set_loop_invariant_loads(
+      ZoneGrowableArray<BitVector*>* loop_invariant_loads) {
+    loop_invariant_loads_ = loop_invariant_loads;
+  }
+
  private:
   friend class IfConverter;
   friend class BranchSimplifier;
   friend class ConstantPropagator;
 
   // SSA transformation methods and fields.
   void ComputeDominators(GrowableArray<BitVector*>* dominance_frontier);
 
   void CompressPath(
       intptr_t start_index,
@@ skipping 15 matching lines @@
   void InsertPhis(
       const GrowableArray<BlockEntryInstr*>& preorder,
       const GrowableArray<BitVector*>& assigned_vars,
       const GrowableArray<BitVector*>& dom_frontier);
 
   void RemoveDeadPhis(GrowableArray<PhiInstr*>* live_phis);
 
   void ReplacePredecessor(BlockEntryInstr* old_block,
                           BlockEntryInstr* new_block);
 
+  // Finds natural loops in the flow graph and attaches a list of loop
+  // body blocks for each loop header.
+  ZoneGrowableArray<BlockEntryInstr*>* ComputeLoops();
+
   // DiscoverBlocks computes parent_ and assigned_vars_ which are then used
   // if/when computing SSA.
   GrowableArray<intptr_t> parent_;
   GrowableArray<BitVector*> assigned_vars_;
 
   intptr_t current_ssa_temp_index_;
   intptr_t max_block_id_;
 
   // Flow graph fields.
   const ParsedFunction& parsed_function_;
   const intptr_t num_copied_params_;
   const intptr_t num_non_copied_params_;
   const intptr_t num_stack_locals_;
   GraphEntryInstr* graph_entry_;
   GrowableArray<BlockEntryInstr*> preorder_;
   GrowableArray<BlockEntryInstr*> postorder_;
   GrowableArray<BlockEntryInstr*> reverse_postorder_;
   ConstantInstr* constant_null_;
 
   BlockEffects* block_effects_;
   bool licm_allowed_;
+
+  ZoneGrowableArray<BlockEntryInstr*>* loop_headers_;
+  ZoneGrowableArray<BitVector*>* loop_invariant_loads_;
 };
 
 
 class LivenessAnalysis : public ValueObject {
  public:
   LivenessAnalysis(intptr_t variable_count,
                    const GrowableArray<BlockEntryInstr*>& postorder);
 
   void Analyze();
 
@@ skipping 85 matching lines @@
   // Per block sets of available blocks. Block A is available at the block B if
   // and only if A dominates B and all paths from A to B are free of side
   // effects.
   GrowableArray<BitVector*> available_at_;
 };
 
 
 }  // namespace dart
 
 #endif  // VM_FLOW_GRAPH_H_