Subzero: Initial O2 lowering

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.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file 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 "IceTypes.h"
+
+namespace Ice {
+
+class LivenessNode {
+public:
+  LivenessNode() : NumLocals(0) {}
+  // NumLocals is the number of Variables local to this block.
+  SizeT NumLocals;
+  // 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.
+  std::vector<Variable *> LiveToVarMap;
+  // LiveIn and LiveOut track the in- and out-liveness of the global
+  // variables.  The size of each vector is
+  // LivenessNode::NumGlobals.
+  llvm::BitVector LiveIn, LiveOut;
+  // LiveBegin and LiveEnd track the instruction numbers of the start
+  // and end of each variable's live range within this block.  The
+  // size of each vector is NumLocals + Liveness::NumGlobals.
+  std::vector<int> LiveBegin, LiveEnd;
+
+private:
+  // TODO: Disable these constructors when Liveness::Nodes is no
+  // longer an STL container.
+  // LivenessNode(const LivenessNode &) LLVM_DELETED_FUNCTION;
+  // LivenessNode &operator=(const LivenessNode &) LLVM_DELETED_FUNCTION;
+};
+
+class Liveness {
+public:
+  Liveness(Cfg *Func, LivenessMode Mode)
+      : Func(Func), Mode(Mode), NumGlobals(0) {}
+  void init();
+  Variable *getVariable(SizeT LiveIndex, const CfgNode *Node) const;
+  SizeT getLiveIndex(const Variable *Var) const;
+  SizeT getNumGlobalVars() const { return NumGlobals; }
+  SizeT getNumVarsInNode(const CfgNode *Node) const {
+    return NumGlobals + Nodes[Node->getIndex()].NumLocals;
+  }
+  llvm::BitVector &getLiveIn(const CfgNode *Node) {
+    return Nodes[Node->getIndex()].LiveIn;
+  }
+  llvm::BitVector &getLiveOut(const CfgNode *Node) {
+    return Nodes[Node->getIndex()].LiveOut;
+  }
+  std::vector<int> &getLiveBegin(const CfgNode *Node) {
+    return Nodes[Node->getIndex()].LiveBegin;
+  }
+  std::vector<int> &getLiveEnd(const CfgNode *Node) {
+    return Nodes[Node->getIndex()].LiveEnd;
+  }
+  LiveRange &getLiveRange(Variable *Var);
+  void addLiveRange(Variable *Var, InstNumberT Start, InstNumberT End,
+                    uint32_t WeightDelta);
+
+private:
+  Cfg *Func;
+  LivenessMode Mode;
+  SizeT NumGlobals;
+  // Size of Nodes is Cfg::Nodes.size().
+  std::vector<LivenessNode> Nodes;
+  // VarToLiveMap maps a Variable's Variable::Number to its live index
+  // within its basic block.
+  std::vector<SizeT> VarToLiveMap;
+  // LiveToVarMap is analogous to LivenessNode::LiveToVarMap, but for
+  // non-local variables.
+  std::vector<Variable *> LiveToVarMap;
+  // LiveRanges maps a Variable::Number to its live range.
+  std::vector<LiveRange> LiveRanges;
+  Liveness(const Liveness &) LLVM_DELETED_FUNCTION;
+  Liveness &operator=(const Liveness &) LLVM_DELETED_FUNCTION;
+};
+
+} // end of namespace Ice
+
+#endif // SUBZERO_SRC_ICELIVENESS_H