Subzero: Completely remove tracking of stack pointer live range.

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 53 matching lines @@
   // the counts to 0.
   for (auto I = FirstNode, E = Func->getNodes().end(); I != E; ++I) {
     LivenessNode &N = Nodes[(*I)->getIndex()];
     N.LiveToVarMap.assign(N.NumLocals, nullptr);
     N.NumLocals = 0;
     N.NumNonDeadPhis = 0;
   }
   if (IsFullInit)
     LiveToVarMap.assign(NumGlobals, nullptr);
 
-  // Sort each variable into the appropriate LiveToVarMap.  Also set
-  // VarToLiveMap.
+  // 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;
     if (VMetadata->isMultiBlock(Var)) {
       LiveIndex = TmpNumGlobals++;
       LiveToVarMap[LiveIndex] = Var;
     } else {
       SizeT NodeIndex = VMetadata->getLocalUseNode(Var)->getIndex();
       LiveIndex = Nodes[NodeIndex].NumLocals++;
       Nodes[NodeIndex].LiveToVarMap[LiveIndex] = Var;
       LiveIndex += NumGlobals;
     }
     VarToLiveMap[VarIndex] = LiveIndex;
+    if (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->getWeight().isInf()))
+      RangeMask[VarIndex] = false;
+  }
+
   // Process each node.
   for (auto I = FirstNode, E = Func->getNodes().end(); I != E; ++I) {
     LivenessNode &Node = Nodes[(*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.
   }
-
-  // Initialize the bitmask of which variables to track.
-  RangeMask.resize(NumVars);
-  RangeMask.set(0, NumVars);
-  if (!IsFullInit) {
-    // Reset initial variables that are not pre-colored or infinite-weight.
-    for (auto I = Func->getVariables().begin(); I != FirstVar; ++I) {
-      Variable *Var = *I;
-      RangeMask[Var->getIndex()] = (Var->hasReg() || Var->getWeight().isInf());
-    }
-  }
 }
 
 void Liveness::init() {
   constexpr bool IsFullInit = true;
   NodeList::const_iterator FirstNode = Func->getNodes().begin();
   VarList::const_iterator FirstVar = Func->getVariables().begin();
   initInternal(FirstNode, FirstVar, IsFullInit);
 }
 
 void Liveness::initPhiEdgeSplits(NodeList::const_iterator FirstNode,
                                  VarList::const_iterator FirstVar) {
   constexpr bool IsFullInit = false;
   initInternal(FirstNode, FirstVar, IsFullInit);
 }
 
 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