Add a basic TargetARM32 skeleton which knows nothing.

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.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file declares the TargetLowering, LoweringContext, and
@@ skipping 77 matching lines @@
   void skipDeleted(InstList::iterator &I) const;
   void advanceForward(InstList::iterator &I) const;
 };
 
 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 std::unique_ptr<Assembler> createAssembler(TargetArch Target,
                                                     Cfg *Func);
   void translate() {
     switch (Ctx->getFlags().getOptLevel()) {
     case Opt_m1:
       translateOm1();
       break;
     case Opt_0:
       translateO0();
@@ skipping 56 matching lines @@
   virtual SizeT getFrameOrStackReg() const = 0;
   virtual size_t typeWidthInBytesOnStack(Type Ty) const = 0;
   bool hasComputedFrame() const { return HasComputedFrame; }
   // Returns true if this function calls a function that has the
   // "returns twice" attribute.
   bool callsReturnsTwice() const { return CallsReturnsTwice; }
   void setCallsReturnsTwice(bool RetTwice) { CallsReturnsTwice = RetTwice; }
   int32_t getStackAdjustment() const { return StackAdjustment; }
   void updateStackAdjustment(int32_t Offset) { StackAdjustment += Offset; }
   void resetStackAdjustment() { StackAdjustment = 0; }
+  SizeT makeNextLabelNumber() { return NextLabelNumber++; }
   LoweringContext &getContext() { return Context; }
 
   enum RegSet {
     RegSet_None = 0,
     RegSet_CallerSave = 1 << 0,
     RegSet_CalleeSave = 1 << 1,
     RegSet_StackPointer = 1 << 2,
     RegSet_FramePointer = 1 << 3,
     RegSet_All = ~RegSet_None
   };
@@ skipping 50 matching lines @@
   virtual void lowerSwitch(const InstSwitch *Inst) = 0;
   virtual void lowerUnreachable(const InstUnreachable *Inst) = 0;
 
   virtual void doAddressOptLoad() {}
   virtual void doAddressOptStore() {}
   virtual void randomlyInsertNop(float Probability) = 0;
   // This gives the target an opportunity to post-process the lowered
   // expansion before returning.
   virtual void postLower() {}
 
+  // Make a call to an external helper function.
+  InstCall *makeHelperCall(const IceString &Name, Variable *Dest,
+                           SizeT MaxSrcs);
+
   Cfg *Func;
   GlobalContext *Ctx;
   bool HasComputedFrame;
   bool CallsReturnsTwice;
   // StackAdjustment keeps track of the current stack offset from its
   // natural location, as arguments are pushed for a function call.
   int32_t StackAdjustment;
+  SizeT NextLabelNumber;
   LoweringContext Context;
 
   // Runtime helper function names
   const static constexpr char *H_bitcast_16xi1_i16 = "__Sz_bitcast_16xi1_i16";
   const static constexpr char *H_bitcast_8xi1_i8 = "__Sz_bitcast_8xi1_i8";
   const static constexpr char *H_bitcast_i16_16xi1 = "__Sz_bitcast_i16_16xi1";
   const static constexpr char *H_bitcast_i8_8xi1 = "__Sz_bitcast_i8_8xi1";
   const static constexpr char *H_call_ctpop_i32 = "__popcountsi2";
   const static constexpr char *H_call_ctpop_i64 = "__popcountdi2";
   const static constexpr char *H_call_longjmp = "longjmp";
@@ skipping 44 matching lines @@
   virtual void lowerConstants() const = 0;
 
 protected:
   explicit TargetDataLowering(GlobalContext *Ctx) : Ctx(Ctx) {}
   GlobalContext *Ctx;
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERING_H