Add -reorder-basic-blocks option and fix nop insertion

src/IceTargetLoweringX86BaseImpl.h

 //===- subzero/src/IceTargetLoweringX86BaseImpl.h - x86 lowering -*- C++ -*-==//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 388 matching lines @@
 
   // Stack frame mapping.
   Func->genFrame();
   if (Func->hasError())
     return;
   Func->dump("After stack frame mapping");
 
   Func->contractEmptyNodes();
   Func->reorderNodes();
 
+  // Shuffle basic block order if -reorder-basic-blocks is enabled.

[Jim Stichnoth, 2015/07/30 16:30:51]

Call Func->shuffleNodes() unconditionally, and check the flag and do the dump
inside that method.

[qining, 2015/07/30 20:25:55]

Done. Done the same with nop insertion.

+  if (Ctx->getFlags().shouldReorderBasicBlocks()) {
+    Func->shuffleNodes();
+    Func->dump("After basic block shuffling");
+  }
+
   // Branch optimization.  This needs to be done just before code emission.  In
   // particular, no transformations that insert or reorder CfgNodes should be
   // done after branch optimization.  We go ahead and do it before nop insertion
   // to reduce the amount of work needed for searching for opportunities.
   Func->doBranchOpt();
   Func->dump("After branch optimization");
 
   // Nop insertion
   if (Ctx->getFlags().shouldDoNopInsertion()) {
     Func->doNopInsertion();
@@ skipping 23 matching lines @@
   regAlloc(RAK_InfOnly);
   if (Func->hasError())
     return;
   Func->dump("After regalloc of infinite-weight variables");
 
   Func->genFrame();
   if (Func->hasError())
     return;
   Func->dump("After stack frame mapping");
 
+  // Shuffle basic block order if -reorder-basic-blocks is enabled.
+  if (Ctx->getFlags().shouldReorderBasicBlocks()) {
+    Func->shuffleNodes();
+    Func->dump("After basic block shuffling");
+  }
+
   // Nop insertion
   if (Ctx->getFlags().shouldDoNopInsertion()) {
     Func->doNopInsertion();
   }
 }
 
 inline bool canRMW(const InstArithmetic *Arith) {
   Type Ty = Arith->getDest()->getType();
   // X86 vector instructions write to a register and have no RMW option.
   if (isVectorType(Ty))
@@ skipping 5154 matching lines @@
   }
   // the offset is not eligible for blinding or pooling, return the original
   // mem operand
   return MemOperand;
 }
 
 } // end of namespace X86Internal
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERINGX86BASEIMPL_H