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

src/IceTargetLowering.h

Index: src/IceTargetLowering.h
diff --git a/src/IceTargetLowering.h b/src/IceTargetLowering.h
index 3d3452e33d075cb5b085f890a4cb082013e960f3..d406fb54ee7031e62aa06be09b46f703285c41de 100644
--- a/src/IceTargetLowering.h
+++ b/src/IceTargetLowering.h
@@ -275,8 +275,15 @@ public:
 
   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);