[CodeGen] Expose some data types and accessors from StackMaps

[cherry]

Summary

This is for supporting custom stack map formats, where the
custom printer can access the stack map data.

Related: https://reviews.llvm.org/D53892

[cherry]

Thanks for the review!

include/llvm/CodeGen/StackMaps.h

public:
   StackMaps(AsmPrinter &AP);
 
   void reset() {
     CSInfos.clear();
     ConstPool.clear();
     FnInfos.clear();
   }
 
-  /// Generate a stackmap record for a stackmap instruction.
-  ///
-  /// MI must be a raw STACKMAP, not a PATCHPOINT.
-  void recordStackMap(const MachineInstr &MI);
-
-  /// Generate a stackmap record for a patchpoint instruction.
-  void recordPatchPoint(const MachineInstr &MI);
-
-  /// Generate a stackmap record for a statepoint instruction.
-  void recordStatepoint(const MachineInstr &MI);
-
-  /// If there is any stack map data, create a stack map section and serialize
-  /// the map info into it. This clears the stack map data structures
-  /// afterwards.
-  void serializeToStackMapSection();
-
-private:
-  static const char *WSMP;
-
   using LocationVec = SmallVector<Location, 8>;
   using LiveOutVec = SmallVector<LiveOutReg, 8>;
   using ConstantPool = MapVector<uint64_t, uint64_t>;
 
   struct FunctionInfo {
     uint64_t StackSize = 0;
     uint64_t RecordCount = 1;
 
CallsiteInfo(const MCExpr *CSOffsetExpr, uint64_t ID,
                  LocationVec &&Locations, LiveOutVec &&LiveOuts)
         : CSOffsetExpr(CSOffsetExpr), ID(ID), Locations(std::move(Locations)),
           LiveOuts(std::move(LiveOuts)) {}
   };
 
   using FnInfoMap = MapVector<const MCSymbol *, FunctionInfo>;
   using CallsiteInfoList = std::vector<CallsiteInfo>;
 
+  /// Generate a stackmap record for a stackmap instruction.
+  ///
+  /// MI must be a raw STACKMAP, not a PATCHPOINT.
+  void recordStackMap(const MachineInstr &MI);
+
+  /// Generate a stackmap record for a patchpoint instruction.
+  void recordPatchPoint(const MachineInstr &MI);
+
+  /// Generate a stackmap record for a statepoint instruction.
+  void recordStatepoint(const MachineInstr &MI);
+
+  /// If there is any stack map data, create a stack map section and serialize
+  /// the map info into it. This clears the stack map data structures
+  /// afterwards.
+  void serializeToStackMapSection();
+
+  /// Get call site info.
+  CallsiteInfoList &getCSInfos() { return CSInfos; }
+
+  /// Get function info.
+  FnInfoMap &getFnInfos() { return FnInfos; }
+
+private:
+  static const char *WSMP;
+
   AsmPrinter &AP;
   CallsiteInfoList CSInfos;
   ConstantPool ConstPool;
   FnInfoMap FnInfos;
 
   MachineInstr::const_mop_iterator
   parseOperand(MachineInstr::const_mop_iterator MOI,
                MachineInstr::const_mop_iterator MOE, LocationVec &Locs,