Compute local variable liveness before translation to SSA.

runtime/vm/flow_graph_allocator.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_ALLOCATOR_H_
 #define VM_FLOW_GRAPH_ALLOCATOR_H_
 
+#include "vm/flow_graph.h"
 #include "vm/growable_array.h"
 #include "vm/intermediate_language.h"
 
 namespace dart {
 
 class AllocationFinger;
 class BlockInfo;
 class FlowGraph;
 class LiveRange;
 class UseInterval;
@@ skipping 10 matching lines @@
 
  private:
   void AddPhi(PhiInstr* phi);
   void Compute();
 
   const FlowGraph& flow_graph_;
   GrowableArray<PhiInstr*> phis_;
 };
 
 
+class SSALivenessAnalysis : public LivenessAnalysis {
+ public:
+  explicit SSALivenessAnalysis(const FlowGraph& flow_graph)
+      : LivenessAnalysis(flow_graph.max_virtual_register_number(),
+                         flow_graph.postorder()),
+        graph_entry_(flow_graph.graph_entry()) { }
+
+ private:
+  // Compute initial values for live-out, kill and live-in sets.
+  virtual void ComputeInitialSets();
+
+  GraphEntryInstr* graph_entry_;
+};
+
+
 class FlowGraphAllocator : public ValueObject {
  public:
   // Number of stack slots needed for a double spill slot.
   static const intptr_t kDoubleSpillSlotFactor = kDoubleSize / kWordSize;
 
   explicit FlowGraphAllocator(const FlowGraph& flow_graph);
 
   void AllocateRegisters();
 
-  // Build live-in and live-out sets for each block.
-  void AnalyzeLiveness();
-
   // Map a virtual register number to its live range.
   LiveRange* GetLiveRange(intptr_t vreg);
 
  private:
   void CollectRepresentations();
 
   // Eliminate unnecessary environments from the IL.
   void EliminateEnvironments();
 
-  // Compute initial values for live-out, kill and live-in sets.
-  void ComputeInitialSets();
-
-  // Update live-out set for the given block: live-out should contain
-  // all values that are live-in for block's successors.
-  // Returns true if live-out set was changed.
-  bool UpdateLiveOut(const BlockEntryInstr& instr);
-
-  // Update live-in set for the given block: live-in should contain
-  // all values that are live-out from the block and are not defined
-  // by this block.
-  // Returns true if live-in set was changed.
-  bool UpdateLiveIn(const BlockEntryInstr& instr);
-
-  // Perform fix-point iteration updating live-out and live-in sets
-  // for blocks until they stop changing.
-  void ComputeLiveInAndLiveOutSets();
-
-  // Print results of liveness analysis.
-  void DumpLiveness();
-
   // Visit blocks in the code generation order (reverse post order) and
   // linearly assign consequent lifetime positions to every instruction.
   // We assign position as follows:
   //
   //    2 * n     - even position corresponding to instruction's start;
   //
   //    2 * n + 1 - odd position corresponding to instruction's end;
   //
   // Having two positions per instruction allows us to capture non-trivial
   // shapes of use intervals: e.g. by placing a use at the start or the
@@ skipping 152 matching lines @@
 
   const GrowableArray<BlockEntryInstr*>& block_order_;
   const GrowableArray<BlockEntryInstr*>& postorder_;
 
   // Mapping between lifetime positions and instructions.
   GrowableArray<Instruction*> instructions_;
 
   // Mapping between lifetime positions and blocks containing them.
   GrowableArray<BlockInfo*> block_info_;
 
-  // Live-out sets for each block.  They contain indices of SSA values
-  // that are live out from this block: that is values that were either
-  // defined in this block or live into it and that are used in some
-  // successor block.
-  GrowableArray<BitVector*> live_out_;
-
-  // Kill sets for each block.  They contain indices of SSA values that
-  // are defined by this block.
-  GrowableArray<BitVector*> kill_;
-
-  // Live-in sets for each block.  They contain indices of SSA values
-  // that are used by this block or its successors.
-  GrowableArray<BitVector*> live_in_;
+  SSALivenessAnalysis liveness_;
 
   // Number of virtual registers.  Currently equal to the number of
   // SSA values.
   const intptr_t vreg_count_;
 
   // LiveRanges corresponding to SSA values.
   GrowableArray<LiveRange*> live_ranges_;
 
   GrowableArray<LiveRange*> unallocated_cpu_;
   GrowableArray<LiveRange*> unallocated_xmm_;
@@ skipping 381 matching lines @@
 
   AllocationFinger finger_;
 
   DISALLOW_COPY_AND_ASSIGN(LiveRange);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_FLOW_GRAPH_ALLOCATOR_H_