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