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       1             : //====- Internalize.h - Internalization API ---------------------*- C++ -*-===//
       2             : //
       3             : //                      The LLVM Compiler Infrastructure
       4             : //
       5             : // This file is distributed under the University of Illinois Open Source
       6             : // License. See LICENSE.TXT for details.
       7             : //
       8             : //===----------------------------------------------------------------------===//
       9             : //
      10             : // This pass loops over all of the functions and variables in the input module.
      11             : // If the function or variable does not need to be preserved according to the
      12             : // client supplied callback, it is marked as internal.
      13             : //
      14             : // This transformation would not be legal in a regular compilation, but it gets
      15             : // extra information from the linker about what is safe.
      16             : //
      17             : // For example: Internalizing a function with external linkage. Only if we are
      18             : // told it is only used from within this module, it is safe to do it.
      19             : //
      20             : //===----------------------------------------------------------------------===//
      21             : 
      22             : #ifndef LLVM_TRANSFORMS_IPO_INTERNALIZE_H
      23             : #define LLVM_TRANSFORMS_IPO_INTERNALIZE_H
      24             : 
      25             : #include "llvm/ADT/StringSet.h"
      26             : #include "llvm/IR/GlobalValue.h"
      27             : #include "llvm/IR/PassManager.h"
      28             : #include <functional>
      29             : #include <set>
      30             : 
      31             : namespace llvm {
      32             : class Module;
      33             : class CallGraph;
      34             : 
      35             : /// A pass that internalizes all functions and variables other than those that
      36             : /// must be preserved according to \c MustPreserveGV.
      37             : class InternalizePass : public PassInfoMixin<InternalizePass> {
      38             :   /// Client supplied callback to control wheter a symbol must be preserved.
      39             :   const std::function<bool(const GlobalValue &)> MustPreserveGV;
      40             :   /// Set of symbols private to the compiler that this pass should not touch.
      41             :   StringSet<> AlwaysPreserved;
      42             : 
      43             :   /// Return false if we're allowed to internalize this GV.
      44             :   bool shouldPreserveGV(const GlobalValue &GV);
      45             :   /// Internalize GV if it is possible to do so, i.e. it is not externally
      46             :   /// visible and is not a member of an externally visible comdat.
      47             :   bool maybeInternalize(GlobalValue &GV,
      48             :                         const std::set<const Comdat *> &ExternalComdats);
      49             :   /// If GV is part of a comdat and is externally visible, keep track of its
      50             :   /// comdat so that we don't internalize any of its members.
      51             :   void checkComdatVisibility(GlobalValue &GV,
      52             :                              std::set<const Comdat *> &ExternalComdats);
      53             : 
      54             : public:
      55             :   InternalizePass();
      56             :   InternalizePass(std::function<bool(const GlobalValue &)> MustPreserveGV)
      57         371 :       : MustPreserveGV(std::move(MustPreserveGV)) {}
      58             : 
      59             :   /// Run the internalizer on \p TheModule, returns true if any changes was
      60             :   /// made.
      61             :   ///
      62             :   /// If the CallGraph \p CG is supplied, it will be updated when
      63             :   /// internalizing a function (by removing any edge from the "external node")
      64             :   bool internalizeModule(Module &TheModule, CallGraph *CG = nullptr);
      65             : 
      66             :   PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
      67             : };
      68             : 
      69             : /// Helper function to internalize functions and variables in a Module.
      70             : inline bool
      71         371 : internalizeModule(Module &TheModule,
      72             :                   std::function<bool(const GlobalValue &)> MustPreserveGV,
      73             :                   CallGraph *CG = nullptr) {
      74         371 :   return InternalizePass(std::move(MustPreserveGV))
      75         371 :       .internalizeModule(TheModule, CG);
      76             : }
      77             : } // end namespace llvm
      78             : 
      79             : #endif // LLVM_TRANSFORMS_IPO_INTERNALIZE_H