Subzero: Minor refactoring/additions in preparation for phi edge splitting.

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 266 matching lines @@
             Var->dump(this);
             Str << " live range " << Var->getLiveRange() << "\n";
           }
         }
       }
     }
   }
   return Valid;
 }
 
+// Deletes redundant assignments like "var=var".  This includes
+// architecturally redundant moves like "var1:eax=var2:eax".  As such,
+// this needs to be done very late in the translation to avoid
+// liveness inconsistencies.
+void Cfg::deleteRedundantAssignments() {
+  for (CfgNode *Node : Nodes) {
+    // Ignore Phi instructions.
+    for (Inst *I : Node->getInsts())
+      if (I->isRedundantAssign())
+        I->setDeleted();
+  }
+}
+
 void Cfg::doBranchOpt() {
   TimerMarker T(TimerStack::TT_doBranchOpt, this);
   for (auto I = Nodes.begin(), E = Nodes.end(); I != E; ++I) {
     auto NextNode = I;
     ++NextNode;
     (*I)->doBranchOpt(NextNode == E ? NULL : *NextNode);
   }
 }
 
 // ======================== Dump routines ======================== //
@@ skipping 66 matching lines @@
     }
   }
   // Print each basic block
   for (CfgNode *Node : Nodes)
     Node->dump(this);
   if (getContext()->isVerbose(IceV_Instructions))
     Str << "}\n";
 }
 
 } // end of namespace Ice