Subzero: Initial O2 lowering

src/IceLiveness.cpp

+//===- subzero/src/IceLiveness.cpp - Liveness analysis implementation -----===//
+//
+//                        The Subzero Code Generator
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides some of the support for the Liveness class.  In
+// particular, it handles the sparsity representation of the mapping
+// between Variables and CfgNodes.  The idea is that since most
+// variables are used only within a single basic block, we can
+// partition the variables into "local" and "global" sets.  Instead of
+// sizing and indexing vectors according to Variable::Number, we
+// create a mapping such that global variables are mapped to low
+// indexes that are common across nodes, and local variables are
+// mapped to a higher index space that is shared across nodes.
+//
+//===----------------------------------------------------------------------===//
+
+#include "IceDefs.h"
+#include "IceCfg.h"
+#include "IceCfgNode.h"
+#include "IceInst.h"
+#include "IceLiveness.h"
+#include "IceOperand.h"
+
+namespace Ice {
+
+void Liveness::init() {
+  // Initialize most of the container sizes.
+  SizeT NumVars = Func->getVariables().size();
+  SizeT NumNodes = Func->getNumNodes();
+  Nodes.resize(NumNodes);
+  VarToLiveMap.resize(NumVars);
+  if (Mode == Liveness_Intervals)
+    LiveRanges.resize(NumVars);
+
+  // Count the number of globals, and the number of locals for each
+  // block.
+  for (SizeT i = 0; i < NumVars; ++i) {
+    Variable *Var = Func->getVariables()[i];
+    if (Var->isMultiblockLife()) {
+      ++NumGlobals;
+    } else {
+      SizeT Index = Var->getLocalUseNode()->getIndex();
+      ++Nodes[Index].NumLocals;
+    }
+  }
+
+  // Resize each LivenessNode::LiveToVarMap, and the global
+  // LiveToVarMap.  Reset the counts to 0.
+  for (SizeT i = 0; i < NumNodes; ++i) {
+    Nodes[i].LiveToVarMap.assign(Nodes[i].NumLocals, NULL);
+    Nodes[i].NumLocals = 0;
+  }
+  LiveToVarMap.assign(NumGlobals, NULL);
+
+  // Sort each variable into the appropriate LiveToVarMap.  Also set
+  // VarToLiveMap.
+  SizeT TmpNumGlobals = 0;
+  for (SizeT i = 0; i < NumVars; ++i) {
+    Variable *Var = Func->getVariables()[i];
+    SizeT VarIndex = Var->getIndex();
+    SizeT LiveIndex;
+    if (Var->isMultiblockLife()) {
+      LiveIndex = TmpNumGlobals++;
+      LiveToVarMap[LiveIndex] = Var;
+    } else {
+      SizeT NodeIndex = Var->getLocalUseNode()->getIndex();
+      LiveIndex = Nodes[NodeIndex].NumLocals++;
+      Nodes[NodeIndex].LiveToVarMap[LiveIndex] = Var;
+      LiveIndex += NumGlobals;
+    }
+    VarToLiveMap[VarIndex] = LiveIndex;
+  }
+  assert(NumGlobals == TmpNumGlobals);
+
+  // Process each node.
+  const NodeList &LNodes = Func->getNodes();
+  SizeT NumLNodes = LNodes.size();
+  for (SizeT i = 0; i < NumLNodes; ++i) {
+    LivenessNode &Node = Nodes[LNodes[i]->getIndex()];
+    // NumLocals, LiveToVarMap already initialized
+    Node.LiveIn.resize(NumGlobals);
+    Node.LiveOut.resize(NumGlobals);
+    // LiveBegin and LiveEnd are reinitialized before each pass over
+    // the block.
+  }
+}
+
+Variable *Liveness::getVariable(SizeT LiveIndex, const CfgNode *Node) const {
+  if (LiveIndex < NumGlobals)
+    return LiveToVarMap[LiveIndex];
+  SizeT NodeIndex = Node->getIndex();
+  return Nodes[NodeIndex].LiveToVarMap[LiveIndex - NumGlobals];
+}
+
+SizeT Liveness::getLiveIndex(const Variable *Var) const {
+  return VarToLiveMap[Var->getIndex()];
+}
+
+void Liveness::addLiveRange(Variable *Var, int32_t Start, int32_t End,
+                            uint32_t WeightDelta) {
+  LiveRange &LiveRange = LiveRanges[Var->getIndex()];
+  assert(WeightDelta != RegWeight::Inf);
+  LiveRange.addSegment(Start, End);
+  LiveRange.addWeight(WeightDelta);
+}
+
+LiveRange &Liveness::getLiveRange(Variable *Var) {
+  return LiveRanges[Var->getIndex()];
+}
+
+} // end of namespace Ice