Subzero: Add branch optimization.

src/IceCfgNode.cpp

 //===- subzero/src/IceCfgNode.cpp - Basic block (node) 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 CfgNode class, including the complexities
@@ skipping 439 matching lines @@
       continue;
     if (Begin <= FirstInstNum)
       Begin = FirstInstNum;
     if (End == Inst::NumberSentinel)
       End = LastInstNum + 1;
     Variable *Var = Liveness->getVariable(i, this);
     Liveness->addLiveRange(Var, Begin, End, 1);
   }
 }
 
+void CfgNode::doBranchOpt(const CfgNode *NextNode) {
+  TargetLowering *Target = Func->getTarget();
+  // Check every instruction for a branch optimization opportunity.
+  // It may be more efficient to iterate in reverse and stop after the
+  // first opportunity, unless there is some target lowering where we
+  // have the possibility of multiple such optimizations per block
+  // (currently not the case for x86 lowering).
+  for (InstList::const_iterator I = Insts.begin(), E = Insts.end(); I != E;
+       ++I) {
+    Target->doBranchOpt(*I, NextNode);
+  }
+}
+
 // ======================== Dump routines ======================== //
 
 void CfgNode::emit(Cfg *Func) const {
   Func->setCurrentNode(this);
   Ostream &Str = Func->getContext()->getStrEmit();
   if (Func->getEntryNode() == this) {
     Str << Func->getContext()->mangleName(Func->getFunctionName()) << ":\n";
   }
   Str << getAsmName() << ":\n";
   for (PhiList::const_iterator I = Phis.begin(), E = Phis.end(); I != E; ++I) {
@@ skipping 95 matching lines @@
          I != E; ++I) {
       if (I != OutEdges.begin())
         Str << ", ";
       Str << "%" << (*I)->getName();
     }
     Str << "\n";
   }
 }
 
 } // end of namespace Ice