Subzero: Make the register allocator more robust with -reg-use and -reg-exclude.

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 257 matching lines @@
     RegSet_CallerSave = 1 << 0,
     RegSet_CalleeSave = 1 << 1,
     RegSet_StackPointer = 1 << 2,
     RegSet_FramePointer = 1 << 3,
     RegSet_All = ~RegSet_None
   };
   using RegSetMask = uint32_t;
 
   virtual llvm::SmallBitVector getRegisterSet(RegSetMask Include,
                                               RegSetMask Exclude) const = 0;
+  /// Get the set of physical registers available for the specified Variable's
+  /// register class, applying register restrictions from the command line.
   virtual const llvm::SmallBitVector &
   getRegistersForVariable(const Variable *Var) const = 0;
+  /// Get the set of *all* physical registers available for the specified
+  /// Variable's register class, *not* applying register restrictions from the
+  /// command line.
+  virtual const llvm::SmallBitVector &
+  getAllRegistersForVariable(const Variable *Var) const = 0;
   virtual const llvm::SmallBitVector &getAliasesForRegister(SizeT) const = 0;
 
   void regAlloc(RegAllocKind Kind);
 
   virtual void
   makeRandomRegisterPermutation(llvm::SmallVectorImpl<int32_t> &Permutation,
                                 const llvm::SmallBitVector &ExcludeRegisters,
                                 uint64_t Salt) const = 0;
 
   /// Get the minimum number of clusters required for a jump table to be
@@ skipping 271 matching lines @@
   virtual void lower() {}
 
 protected:
   explicit TargetHeaderLowering(GlobalContext *Ctx) : Ctx(Ctx) {}
   GlobalContext *Ctx;
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERING_H