1 //===- SymbolRewriter.h - Symbol Rewriting Pass -----------------*- 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 file provides the prototypes and definitions related to the Symbol 10 // Rewriter pass. 11 // 12 // The Symbol Rewriter pass takes a set of rewrite descriptors which define 13 // transformations for symbol names. These can be either single name to name 14 // trnsformation or more broad regular expression based transformations. 15 // 16 // All the functions are re-written at the IR level. The Symbol Rewriter itself 17 // is exposed as a module level pass. All symbols at the module level are 18 // iterated. For any matching symbol, the requested transformation is applied, 19 // updating references to it as well (a la RAUW). The resulting binary will 20 // only contain the rewritten symbols. 21 // 22 // By performing this operation in the compiler, we are able to catch symbols 23 // that would otherwise not be possible to catch (e.g. inlined symbols). 24 // 25 // This makes it possible to cleanly transform symbols without resorting to 26 // overly-complex macro tricks and the pre-processor. An example of where this 27 // is useful is the sanitizers where we would like to intercept a well-defined 28 // set of functions across the module. 29 // 30 //===----------------------------------------------------------------------===// 31 32 #ifndef LLVM_TRANSFORMS_UTILS_SYMBOLREWRITER_H 33 #define LLVM_TRANSFORMS_UTILS_SYMBOLREWRITER_H 34 35 #include "llvm/IR/PassManager.h" 36 #include <list> 37 #include <memory> 38 #include <string> 39 40 namespace llvm { 41 42 class MemoryBuffer; 43 class Module; 44 class ModulePass; 45 46 namespace yaml { 47 48 class KeyValueNode; 49 class MappingNode; 50 class ScalarNode; 51 class Stream; 52 53 } // end namespace yaml 54 55 namespace SymbolRewriter { 56 57 /// The basic entity representing a rewrite operation. It serves as the base 58 /// class for any rewrite descriptor. It has a certain set of specializations 59 /// which describe a particular rewrite. 60 /// 61 /// The RewriteMapParser can be used to parse a mapping file that provides the 62 /// mapping for rewriting the symbols. The descriptors individually describe 63 /// whether to rewrite a function, global variable, or global alias. Each of 64 /// these can be selected either by explicitly providing a name for the ones to 65 /// be rewritten or providing a (posix compatible) regular expression that will 66 /// select the symbols to rewrite. This descriptor list is passed to the 67 /// SymbolRewriter pass. 68 class RewriteDescriptor { 69 public: 70 enum class Type { 71 Invalid, /// invalid 72 Function, /// function - descriptor rewrites a function 73 GlobalVariable, /// global variable - descriptor rewrites a global variable 74 NamedAlias, /// named alias - descriptor rewrites a global alias 75 }; 76 77 RewriteDescriptor(const RewriteDescriptor &) = delete; 78 RewriteDescriptor &operator=(const RewriteDescriptor &) = delete; 79 virtual ~RewriteDescriptor() = default; 80 81 Type getType() const { return Kind; } 82 83 virtual bool performOnModule(Module &M) = 0; 84 85 protected: 86 explicit RewriteDescriptor(Type T) : Kind(T) {} 87 88 private: 89 const Type Kind; 90 }; 91 92 using RewriteDescriptorList = std::list<std::unique_ptr<RewriteDescriptor>>; 93 94 class RewriteMapParser { 95 public: 96 bool parse(const std::string &MapFile, RewriteDescriptorList *Descriptors); 97 98 private: 99 bool parse(std::unique_ptr<MemoryBuffer> &MapFile, RewriteDescriptorList *DL); 100 bool parseEntry(yaml::Stream &Stream, yaml::KeyValueNode &Entry, 101 RewriteDescriptorList *DL); 102 bool parseRewriteFunctionDescriptor(yaml::Stream &Stream, 103 yaml::ScalarNode *Key, 104 yaml::MappingNode *Value, 105 RewriteDescriptorList *DL); 106 bool parseRewriteGlobalVariableDescriptor(yaml::Stream &Stream, 107 yaml::ScalarNode *Key, 108 yaml::MappingNode *Value, 109 RewriteDescriptorList *DL); 110 bool parseRewriteGlobalAliasDescriptor(yaml::Stream &YS, yaml::ScalarNode *K, 111 yaml::MappingNode *V, 112 RewriteDescriptorList *DL); 113 }; 114 115 } // end namespace SymbolRewriter 116 117 ModulePass *createRewriteSymbolsPass(); 118 ModulePass *createRewriteSymbolsPass(SymbolRewriter::RewriteDescriptorList &); 119 120 class RewriteSymbolPass : public PassInfoMixin<RewriteSymbolPass> { 121 public: 122 RewriteSymbolPass() { loadAndParseMapFiles(); } 123 124 RewriteSymbolPass(SymbolRewriter::RewriteDescriptorList &DL) { 125 Descriptors.splice(Descriptors.begin(), DL); 126 } 127 128 PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM); 129 130 // Glue for old PM 131 bool runImpl(Module &M); 132 133 private: 134 void loadAndParseMapFiles(); 135 136 SymbolRewriter::RewriteDescriptorList Descriptors; 137 }; 138 139 } // end namespace llvm 140 141 #endif // LLVM_TRANSFORMS_UTILS_SYMBOLREWRITER_H 142
Indexes created Thu Sep 24 00:25:51 UTC 2026