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      1 //===-- llvm/IR/ModuleSlotTracker.h -----------------------------*- C++ -*-===//
      2 //
      3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
      4 // See https://llvm.org/LICENSE.txt for license information.
      5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
      6 //
      7 //===----------------------------------------------------------------------===//
      8 
      9 #ifndef LLVM_IR_MODULESLOTTRACKER_H
     10 #define LLVM_IR_MODULESLOTTRACKER_H
     11 
     12 #include <memory>
     13 
     14 namespace llvm {
     15 
     16 class Module;
     17 class Function;
     18 class SlotTracker;
     19 class Value;
     20 
     21 /// Manage lifetime of a slot tracker for printing IR.
     22 ///
     23 /// Wrapper around the \a SlotTracker used internally by \a AsmWriter.  This
     24 /// class allows callers to share the cost of incorporating the metadata in a
     25 /// module or a function.
     26 ///
     27 /// If the IR changes from underneath \a ModuleSlotTracker, strings like
     28 /// "<badref>" will be printed, or, worse, the wrong slots entirely.
     29 class ModuleSlotTracker {
     30   /// Storage for a slot tracker.
     31   std::unique_ptr<SlotTracker> MachineStorage;
     32   bool ShouldCreateStorage = false;
     33   bool ShouldInitializeAllMetadata = false;
     34 
     35   const Module *M = nullptr;
     36   const Function *F = nullptr;
     37   SlotTracker *Machine = nullptr;
     38 
     39 public:
     40   /// Wrap a preinitialized SlotTracker.
     41   ModuleSlotTracker(SlotTracker &Machine, const Module *M,
     42                     const Function *F = nullptr);
     43 
     44   /// Construct a slot tracker from a module.
     45   ///
     46   /// If \a M is \c nullptr, uses a null slot tracker.  Otherwise, initializes
     47   /// a slot tracker, and initializes all metadata slots.  \c
     48   /// ShouldInitializeAllMetadata defaults to true because this is expected to
     49   /// be shared between multiple callers, and otherwise MDNode references will
     50   /// not match up.
     51   explicit ModuleSlotTracker(const Module *M,
     52                              bool ShouldInitializeAllMetadata = true);
     53 
     54   /// Destructor to clean up storage.
     55   ~ModuleSlotTracker();
     56 
     57   /// Lazily creates a slot tracker.
     58   SlotTracker *getMachine();
     59 
     60   const Module *getModule() const { return M; }
     61   const Function *getCurrentFunction() const { return F; }
     62 
     63   /// Incorporate the given function.
     64   ///
     65   /// Purge the currently incorporated function and incorporate \c F.  If \c F
     66   /// is currently incorporated, this is a no-op.
     67   void incorporateFunction(const Function &F);
     68 
     69   /// Return the slot number of the specified local value.
     70   ///
     71   /// A function that defines this value should be incorporated prior to calling
     72   /// this method.
     73   /// Return -1 if the value is not in the function's SlotTracker.
     74   int getLocalSlot(const Value *V);
     75 };
     76 
     77 } // end namespace llvm
     78 
     79 #endif
     80