Subzero: Refactor some common TargetLowering initializations.

src/IceTargetLowering.h

 //===- subzero/src/IceTargetLowering.h - Lowering interface -----*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 118 matching lines @@
 };
 
 class TargetLowering {
   TargetLowering() = delete;
   TargetLowering(const TargetLowering &) = delete;
   TargetLowering &operator=(const TargetLowering &) = delete;
 
 public:
   // TODO(jvoung): return a unique_ptr like the other factory functions.
   static TargetLowering *createLowering(TargetArch Target, Cfg *Func);
+  static void staticInit(TargetArch Target);
+  // Each target must define a public static method:
+  //   static void staticInit();
   static std::unique_ptr<Assembler> createAssembler(TargetArch Target,
                                                     Cfg *Func);
   void translate() {
     switch (Ctx->getFlags().getOptLevel()) {
     case Opt_m1:
       translateOm1();
       break;
     case Opt_0:
       translateO0();
       break;
@@ skipping 325 matching lines @@
   virtual void lower() {}
 
 protected:
   explicit TargetHeaderLowering(GlobalContext *Ctx) : Ctx(Ctx) {}
   GlobalContext *Ctx;
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERING_H