Subzero: Minor refactoring/additions in preparation for phi edge splitting.

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 and LoweringContext
@@ skipping 21 matching lines @@
 // instructions in a node, and insert new (lowered) instructions at
 // the current point.  Along with the instruction list container and
 // associated iterators, it holds the current node, which is needed
 // when inserting new instructions in order to track whether variables
 // are used as single-block or multi-block.
 class LoweringContext {
   LoweringContext(const LoweringContext &) = delete;
   LoweringContext &operator=(const LoweringContext &) = delete;
 
 public:
-  LoweringContext() : Node(NULL) {}
+  LoweringContext() : Node(NULL), LastInserted(NULL) {}
   ~LoweringContext() {}
   void init(CfgNode *Node);
   Inst *getNextInst() const {
     if (Next == End)
       return NULL;
     return *Next;
   }
   Inst *getNextInst(InstList::iterator &Iter) const {
     advanceForward(Iter);
     if (Iter == End)
       return NULL;
     return *Iter;
   }
   CfgNode *getNode() const { return Node; }
   bool atEnd() const { return Cur == End; }
   InstList::iterator getCur() const { return Cur; }
   InstList::iterator getEnd() const { return End; }
   // Adaptor to enable range-based for loops.
   InstList::iterator begin() const { return getCur(); }
   InstList::iterator end() const { return getEnd(); }
   void insert(Inst *Inst);
   Inst *getLastInserted() const;
   void advanceCur() { Cur = Next; }
   void advanceNext() { advanceForward(Next); }
   void setInsertPoint(const InstList::iterator &Position) { Next = Position; }
 
 private:
   // Node is the argument to Inst::updateVars().
   CfgNode *Node;
+  Inst *LastInserted;
   // Cur points to the current instruction being considered.  It is
   // guaranteed to point to a non-deleted instruction, or to be End.
   InstList::iterator Cur;
   // Next doubles as a pointer to the next valid instruction (if any),
   // and the new-instruction insertion point.  It is also updated for
   // the caller in case the lowering consumes more than one high-level
   // instruction.  It is guaranteed to point to a non-deleted
   // instruction after Cur, or to be End.  TODO: Consider separating
   // the notion of "next valid instruction" and "new instruction
   // insertion point", to avoid confusion when previously-deleted
   // instructions come between the two points.
   InstList::iterator Next;
   // Begin is a copy of Insts.begin(), used if iterators are moved backward.
   InstList::iterator Begin;
   // End is a copy of Insts.end(), used if Next needs to be advanced.
   InstList::iterator End;
 
   void skipDeleted(InstList::iterator &I) const;
   void advanceForward(InstList::iterator &I) const;
-  void advanceBackward(InstList::iterator &I) const;
 };
 
 class TargetLowering {
   TargetLowering(const TargetLowering &) = delete;
   TargetLowering &operator=(const TargetLowering &) = delete;
 
 public:
   static TargetLowering *createLowering(TargetArch Target, Cfg *Func);
   static Assembler *createAssembler(TargetArch Target, Cfg *Func);
   void translate() {
@@ skipping 36 matching lines @@
   void lower();
   // Tries to do branch optimization on a single instruction.  Returns
   // true if some optimization was done.
   virtual bool doBranchOpt(Inst * /*I*/, const CfgNode * /*NextNode*/) {
     return false;
   }
 
   // Returns a variable pre-colored to the specified physical
   // register.  This is generally used to get very direct access to
   // the register such as in the prolog or epilog or for marking
-  // scratch registers as killed by a call.
-  virtual Variable *getPhysicalRegister(SizeT RegNum) = 0;
+  // scratch registers as killed by a call.  If a Type is not
+  // provided, a target-specific default type is used.
+  virtual Variable *getPhysicalRegister(SizeT RegNum,
+                                        Type Ty = IceType_void) = 0;
   // Returns a printable name for the register.
   virtual IceString getRegName(SizeT RegNum, Type Ty) const = 0;
 
   virtual bool hasFramePointer() const { return false; }
   virtual SizeT getFrameOrStackReg() const = 0;
   virtual size_t typeWidthInBytesOnStack(Type Ty) const = 0;
   virtual SizeT getBundleAlignLog2Bytes() const = 0;
   virtual llvm::ArrayRef<AsmCodeByte> getNonExecBundlePadding() const = 0;
   bool hasComputedFrame() const { return HasComputedFrame; }
   bool shouldDoNopInsertion() const;
@@ skipping 95 matching lines @@
   virtual void lower(const VariableDeclaration &Var) = 0;
 
 protected:
   TargetGlobalInitLowering(GlobalContext *Ctx) : Ctx(Ctx) {}
   GlobalContext *Ctx;
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERING_H