Subzero: Ignore variables with no actual uses.

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.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 32 matching lines @@
   VariablesMetadata *VMetadata = Func->getVMetadata();
   Nodes.resize(NumNodes);
   VarToLiveMap.resize(NumVars);
 
   // Count the number of globals, and the number of locals for each block.
   SizeT TmpNumGlobals = 0;
   for (auto I = FirstVar, E = Func->getVariables().end(); I != E; ++I) {
     Variable *Var = *I;
     if (VMetadata->isMultiBlock(Var)) {
       ++TmpNumGlobals;
-    } else {
+    } else if (VMetadata->isSingleBlock(Var)) {
       SizeT Index = VMetadata->getLocalUseNode(Var)->getIndex();
       ++Nodes[Index].NumLocals;
     }
   }
   if (IsFullInit)
     NumGlobals = TmpNumGlobals;
   else
     assert(TmpNumGlobals == 0);
 
   // Resize each LivenessNode::LiveToVarMap, and the global LiveToVarMap. Reset
@@ skipping 10 matching lines @@
   // Initialize the bitmask of which variables to track.
   RangeMask.resize(NumVars);
   RangeMask.set(0, NumVars); // Track all variables by default.
 
   // Sort each variable into the appropriate LiveToVarMap. Set VarToLiveMap.
   // Set RangeMask correctly for each variable.
   TmpNumGlobals = 0;
   for (auto I = FirstVar, E = Func->getVariables().end(); I != E; ++I) {
     Variable *Var = *I;
     SizeT VarIndex = Var->getIndex();
-    SizeT LiveIndex;
+    SizeT LiveIndex = InvalidLiveIndex;
     if (VMetadata->isMultiBlock(Var)) {
       LiveIndex = TmpNumGlobals++;
       LiveToVarMap[LiveIndex] = Var;
-    } else {
+    } else if (VMetadata->isSingleBlock(Var)) {
       SizeT NodeIndex = VMetadata->getLocalUseNode(Var)->getIndex();
       LiveIndex = Nodes[NodeIndex].NumLocals++;
       Nodes[NodeIndex].LiveToVarMap[LiveIndex] = Var;
       LiveIndex += NumGlobals;
     }
     VarToLiveMap[VarIndex] = LiveIndex;
-    if (Var->getIgnoreLiveness())
+    if (LiveIndex == InvalidLiveIndex || Var->getIgnoreLiveness())
       RangeMask[VarIndex] = false;
   }
   assert(TmpNumGlobals == (IsFullInit ? NumGlobals : 0));
 
   // Fix up RangeMask for variables before FirstVar.
   for (auto I = Func->getVariables().begin(); I != FirstVar; ++I) {
     Variable *Var = *I;
     SizeT VarIndex = Var->getIndex();
     if (Var->getIgnoreLiveness() ||
         (!IsFullInit && !Var->hasReg() && !Var->mustHaveReg()))
@@ skipping 27 matching lines @@
 }
 
 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];
 }
 
 } // end of namespace Ice