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

src/IceTargetLoweringX8632.h

 //===- subzero/src/IceTargetLoweringX8632.h - x86-32 lowering ---*- 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 TargetLoweringX8632 class, which
@@ skipping 28 matching lines @@
   virtual bool hasFramePointer() const { return IsEbpBasedFrame; }
   virtual SizeT getFrameOrStackReg() const {
     return IsEbpBasedFrame ? Reg_ebp : Reg_esp;
   }
   virtual size_t typeWidthInBytesOnStack(Type Ty) {
     // Round up to the next multiple of 4 bytes.  In particular, i1,
     // i8, and i16 are rounded up to 4 bytes.
     return (typeWidthInBytes(Ty) + 3) & ~3;
   }
   virtual void emitVariable(const Variable *Var, const Cfg *Func) const;
+  virtual void lowerArguments();
   virtual void addProlog(CfgNode *Node);
   virtual void addEpilog(CfgNode *Node);
   virtual void emitConstants() const;
   SizeT makeNextLabelNumber() { return NextLabelNumber++; }
   // Ensure that a 64-bit Variable has been split into 2 32-bit
   // Variables, creating them if necessary.  This is needed for all
   // I64 operations, and it is needed for pushing F64 arguments for
   // function calls using the 32-bit push instruction (though the
   // latter could be done by directly writing to the stack).
   void split64(Variable *Var);
-  void setArgOffsetAndCopy(Variable *Arg, Variable *FramePtr,
-                           size_t BasicFrameOffset, size_t &InArgsSizeBytes);
+  void finishArgumentLowering(Variable *Arg, Variable *FramePtr,
+                              size_t BasicFrameOffset, size_t &InArgsSizeBytes);
   Operand *loOperand(Operand *Operand);
   Operand *hiOperand(Operand *Operand);
 
   enum Registers {
 #define X(val, init, name, name16, name8, scratch, preserved, stackptr,        \
           frameptr, isI8, isInt, isFP)                                         \
   val init,
     REGX8632_TABLE
 #undef X
         Reg_NUM
@@ skipping 250 matching lines @@
   virtual ~TargetGlobalInitX8632() {}
 };
 
 template <> void ConstantInteger::emit(GlobalContext *Ctx) const;
 template <> void ConstantFloat::emit(GlobalContext *Ctx) const;
 template <> void ConstantDouble::emit(GlobalContext *Ctx) const;
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERINGX8632_H