Move CalculateRegClass to MRI::recomputeRegClass.

This function doesn't have anything to do with spill weights, and MRI
already has functions for manipulating the register class of a virtual
register.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@137123 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/CalcSpillWeights.h

@@ -49,11 +49,6 @@ namespace llvm {
                    const MachineLoopInfo &loops) :
       MF(mf), LIS(lis), Loops(loops) {}
 
-    /// CalculateRegClass - recompute the register class for reg from its uses.
-    /// Since the register class can affect the allocation hint, this function
-    /// should be called before CalculateWeightAndHint if both are called.
-    void CalculateRegClass(unsigned reg);
-
     /// CalculateWeightAndHint - (re)compute li's spill weight and allocation
     /// hint.
     void CalculateWeightAndHint(LiveInterval &li);

include/llvm/CodeGen/MachineRegisterInfo.h

@@ -219,9 +219,20 @@ public:
   /// Return the new register class, or NULL if no such class exists.
   /// This should only be used when the constraint is known to be trivial, like
   /// GR32 -> GR32_NOSP. Beware of increasing register pressure.
+  ///
   const TargetRegisterClass *constrainRegClass(unsigned Reg,
                                                const TargetRegisterClass *RC);
 
+  /// recomputeRegClass - Try to find a legal super-class of Reg's register
+  /// class that still satisfies the constraints from the instructions using
+  /// Reg.  Returns true if Reg was upgraded.
+  ///
+  /// This method can be used after constraints have been removed from a
+  /// virtual register, for example after removing instructions or splitting
+  /// the live range.
+  ///
+  bool recomputeRegClass(unsigned Reg, const TargetMachine&);
+
   /// createVirtualRegister - Create and return a new virtual register in the
   /// function with the specified register class.
   ///