Add support for passing and returning vectors in accordance with the x86 calling convention.

src/IceCfg.h

 //===- subzero/src/IceCfg.h - Control flow graph ----------------*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file declares the Cfg class, which represents the control flow
@@ skipping 51 matching lines @@
 
   // Manage Variables.
   Variable *makeVariable(Type Ty, const CfgNode *Node,
                          const IceString &Name = "");
   SizeT getNumVariables() const { return Variables.size(); }
   const VarList &getVariables() const { return Variables; }
 
   // Manage arguments to the function.
   void addArg(Variable *Arg);
   const VarList &getArgs() const { return Args; }
+  VarList &getArgs() { return Args; }
 
   // Miscellaneous accessors.
   TargetLowering *getTarget() const { return Target.get(); }
   Liveness *getLiveness() const { return Live.get(); }
   bool hasComputedFrame() const;
 
   // Passes over the CFG.
   void translate();
   // After the CFG is fully constructed, iterate over the nodes and
   // compute the predecessor edges, in the form of
   // CfgNode::InEdges[].
   void computePredecessors();
   void renumberInstructions();
   void placePhiLoads();
   void placePhiStores();
   void deletePhis();
   void doAddressOpt();
+  void doArgLowering();
   void genCode();
   void genFrame();
   void livenessLightweight();
   void liveness(LivenessMode Mode);
   bool validateLiveness() const;
 
   // Manage the CurrentNode field, which is used for validating the
   // Variable::DefNode field during dumping/emitting.
   void setCurrentNode(const CfgNode *Node) { CurrentNode = Node; }
   const CfgNode *getCurrentNode() const { return CurrentNode; }
@@ skipping 56 matching lines @@
   // avoid spurious validation failures.
   const CfgNode *CurrentNode;
 
   Cfg(const Cfg &) LLVM_DELETED_FUNCTION;
   Cfg &operator=(const Cfg &) LLVM_DELETED_FUNCTION;
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICECFG_H