Subzero: Randomly insert nops.

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 173 matching lines @@
 // instruction and delete the old.
 void CfgNode::doAddressOpt() {
   TargetLowering *Target = Func->getTarget();
   LoweringContext &Context = Target->getContext();
   Context.init(this);
   while (!Context.atEnd()) {
     Target->doAddressOpt();
   }
 }
 
+void CfgNode::doNopInsertion() {
+  TargetLowering *Target = Func->getTarget();
+  LoweringContext &Context = Target->getContext();
+  Context.init(this);
+  while (!Context.atEnd()) {
+    Target->doNopInsertion();
+    // Ensure Cur=Next, so that the nops are inserted before the current
+    // instruction rather than after.
+    Context.advanceNext();
+    Context.advanceCur();
+  }
+  // Insert before all instructions.
+  Context.setInsertPoint(getInsts().begin());
+  Context.advanceNext();
+  Context.advanceCur();
+  Target->doNopInsertion();
+}
+
 // Drives the target lowering.  Passes the current instruction and the
 // next non-deleted instruction for target lowering.
 void CfgNode::genCode() {
   TargetLowering *Target = Func->getTarget();
   LoweringContext &Context = Target->getContext();
   // Lower only the regular instructions.  Defer the Phi instructions.
   Context.init(this);
   while (!Context.atEnd()) {
     InstList::iterator Orig = Context.getCur();
     if (llvm::isa<InstRet>(*Orig))
@@ skipping 281 matching lines @@
          I != E; ++I) {
       if (I != OutEdges.begin())
         Str << ", ";
       Str << "%" << (*I)->getName();
     }
     Str << "\n";
   }
 }
 
 } // end of namespace Ice