Subzero: Improve the representation and handling of the FakeKill instruction.

src/IceCfg.cpp

 //===- subzero/src/IceCfg.cpp - Control flow graph implementation ---------===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements the Cfg class, including constant pool
@@ skipping 298 matching lines @@
 // appears within the Variable's computed live range.
 bool Cfg::validateLiveness() const {
   TimerMarker T(TimerStack::TT_validateLiveness, this);
   bool Valid = true;
   Ostream &Str = Ctx->getStrDump();
   for (CfgNode *Node : Nodes) {
     Inst *FirstInst = NULL;
     for (Inst *Inst : Node->getInsts()) {
       if (Inst->isDeleted())
         continue;
-      if (llvm::isa<InstFakeKill>(Inst))
-        continue;
       if (FirstInst == NULL)
         FirstInst = Inst;
       InstNumberT InstNumber = Inst->getNumber();
       if (Variable *Dest = Inst->getDest()) {
         if (!Dest->getIgnoreLiveness()) {
           bool Invalid = false;
           const bool IsDest = true;
           if (!Dest->getLiveRange().containsValue(InstNumber, IsDest))
             Invalid = true;
           // Check that this instruction actually *begins* Dest's live
@@ skipping 132 matching lines @@
     }
   }
   // Print each basic block
   for (CfgNode *Node : Nodes)
     Node->dump(this);
   if (getContext()->isVerbose(IceV_Instructions))
     Str << "}\n";
 }
 
 } // end of namespace Ice