Subzero. Liveness memory management.

src/IceLiveness.h

 //===- subzero/src/IceLiveness.h - Liveness analysis ------------*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
 /// \brief Declares the Liveness and LivenessNode classes, which are used for
 /// liveness analysis.
 ///
 /// The node-specific information tracked for each Variable includes whether it
 /// is live on entry, whether it is live on exit, the instruction number that
 /// starts its live range, and the instruction number that ends its live range.
 /// At the Cfg level, the actual live intervals are recorded.
 ///
 //===----------------------------------------------------------------------===//
 
 #ifndef SUBZERO_SRC_ICELIVENESS_H
 #define SUBZERO_SRC_ICELIVENESS_H
 
 #include "IceDefs.h"
 #include "IceBitVector.h"
 #include "IceCfgNode.h"
+#include "IceTLS.h"
 #include "IceTypes.h"
 
+#include <memory>
+#include <utility>
+
 namespace Ice {
 
 class Liveness {
   Liveness() = delete;
   Liveness(const Liveness &) = delete;
   Liveness &operator=(const Liveness &) = delete;
 
   class LivenessNode {
     LivenessNode &operator=(const LivenessNode &) = delete;
 
   public:
     LivenessNode() = default;
     LivenessNode(const LivenessNode &) = default;
     /// NumLocals is the number of Variables local to this block.
     SizeT NumLocals = 0;
     /// NumNonDeadPhis tracks the number of Phi instructions that
     /// Inst::liveness() identified as tentatively live. If NumNonDeadPhis
     /// changes from the last liveness pass, then liveness has not yet
     /// converged.
     SizeT NumNonDeadPhis = 0;
     // LiveToVarMap maps a liveness bitvector index to a Variable. This is
     // generally just for printing/dumping. The index should be less than
     // NumLocals + Liveness::NumGlobals.
-    CfgVector<Variable *> LiveToVarMap;
+    LivenessVector<Variable *> LiveToVarMap;
     // LiveIn and LiveOut track the in- and out-liveness of the global
     // variables. The size of each vector is LivenessNode::NumGlobals.
     LivenessBV LiveIn, LiveOut;
     // LiveBegin and LiveEnd track the instruction numbers of the start and end
     // of each variable's live range within this block. The index/key of each
     // element is less than NumLocals + Liveness::NumGlobals.
     LiveBeginEndMap LiveBegin, LiveEnd;
   };
 
 public:
-  Liveness(Cfg *Func, LivenessMode Mode) : Func(Func), Mode(Mode) {}
   void init();
   void initPhiEdgeSplits(NodeList::const_iterator FirstNode,
                          VarList::const_iterator FirstVar);
   Cfg *getFunc() const { return Func; }
   LivenessMode getMode() const { return Mode; }
   Variable *getVariable(SizeT LiveIndex, const CfgNode *Node) const;
   SizeT getLiveIndex(SizeT VarIndex) const { return VarToLiveMap[VarIndex]; }
   SizeT getNumGlobalVars() const { return NumGlobals; }
   SizeT getNumVarsInNode(const CfgNode *Node) const {
     return NumGlobals + Nodes[Node->getIndex()].NumLocals;
@@ skipping 17 matching lines @@
     resize(Index);
     return &Nodes[Index].LiveBegin;
   }
   LiveBeginEndMap *getLiveEnd(const CfgNode *Node) {
     SizeT Index = Node->getIndex();
     resize(Index);
     return &Nodes[Index].LiveEnd;
   }
   bool getRangeMask(SizeT Index) const { return RangeMask[Index]; }
 
+  ArenaAllocator *getAllocator() const { return Alloc.get(); }
+
+  static std::unique_ptr<Liveness> create(Cfg *Func, LivenessMode Mode) {
+    return std::unique_ptr<Liveness>(new Liveness(Func, Mode));
+  }
+
+  static void TlsInit() { LivenessAllocatorTraits::init(); }
+
+  std::string dumpStr() const {
+    return "MaxLocals(" + std::to_string(MaxLocals) + "), "
+                                                      "NumGlobals(" +
+           std::to_string(NumGlobals) + ")";
+  }
+
 private:
+  SizeT MaxLocals = 0;

[Jim Stichnoth, 2016/03/31 16:23:20]

Should these data members be grouped with the other private data members below?

[John, 2016/04/01 13:52:04]

Done.

+  SizeT NumGlobals = 0;
+
+  Liveness(Cfg *Func, LivenessMode Mode)
+      : Alloc(new ArenaAllocator()), AllocScope(this), Func(Func), Mode(Mode) {}
+
   void initInternal(NodeList::const_iterator FirstNode,
                     VarList::const_iterator FirstVar, bool IsFullInit);
   /// Resize Nodes so that Nodes[Index] is valid.
   void resize(SizeT Index) {
-    if (Index >= Nodes.size())
+    if (Index >= Nodes.size()) {
+      assert(false);

[Jim Stichnoth, 2016/03/31 16:23:20]

I like this very much.  What do you think about renaming this function to
something like checkSize(), with a report_fatal_error()?

[John, 2016/04/01 13:52:04]

I would expect the code to work correctly if the array needs to be resized. It
is just that we do not expect the resize to be needed. That's why I went with
the assert in lieu of the fatal error. I left as is, but no strong opinions what
so ever -- I can change if you want.

       Nodes.resize(Index + 1);
+    }
   }
+  std::unique_ptr<ArenaAllocator> Alloc;
+  LivenessAllocatorScope AllocScope; // Must be declared after Alloc.
   Cfg *Func;
   LivenessMode Mode;
-  SizeT NumGlobals = 0;
   /// Size of Nodes is Cfg::Nodes.size().
-  CfgVector<LivenessNode> Nodes;
+  LivenessVector<LivenessNode> Nodes;
   /// VarToLiveMap maps a Variable's Variable::Number to its live index within
   /// its basic block.
-  CfgVector<SizeT> VarToLiveMap;
+  LivenessVector<SizeT> VarToLiveMap;
   /// LiveToVarMap is analogous to LivenessNode::LiveToVarMap, but for non-local
   /// variables.
-  CfgVector<Variable *> LiveToVarMap;
+  LivenessVector<Variable *> LiveToVarMap;
   /// RangeMask[Variable::Number] indicates whether we want to track that
   /// Variable's live range.
   LivenessBV RangeMask;
   /// ScratchBV is a bitvector that can be reused across CfgNode passes, to
   /// avoid having to allocate/deallocate memory so frequently.
   LivenessBV ScratchBV;
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICELIVENESS_H