1 //===- SymbolRewriter.h - Symbol Rewriting Pass -----------------*- 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 file provides the prototypes and definitions related to the Symbol 11 // Rewriter pass. 12 // 13 // The Symbol Rewriter pass takes a set of rewrite descriptors which define 14 // transformations for symbol names. These can be either single name to name 15 // trnsformation or more broad regular expression based transformations. 16 // 17 // All the functions are re-written at the IR level. The Symbol Rewriter itself 18 // is exposed as a module level pass. All symbols at the module level are 19 // iterated. For any matching symbol, the requested transformation is applied, 20 // updating references to it as well (a la RAUW). The resulting binary will 21 // only contain the rewritten symbols. 22 // 23 // By performing this operation in the compiler, we are able to catch symbols 24 // that would otherwise not be possible to catch (e.g. inlined symbols). 25 // 26 // This makes it possible to cleanly transform symbols without resorting to 27 // overly-complex macro tricks and the pre-processor. An example of where this 28 // is useful is the sanitizers where we would like to intercept a well-defined 29 // set of functions across the module. 30 // 31 //===----------------------------------------------------------------------===// 32 33 #ifndef LLVM_TRANSFORMS_UTILS_SYMBOLREWRITER_H 34 #define LLVM_TRANSFORMS_UTILS_SYMBOLREWRITER_H 35 36 #include "llvm/IR/PassManager.h" 37 #include <list> 38 #include <memory> 39 #include <string> 40 41 namespace llvm { 42 43 class MemoryBuffer; 44 class Module; 45 class ModulePass; 46 47 namespace yaml { 48 49 class KeyValueNode; 50 class MappingNode; 51 class ScalarNode; 52 class Stream; 53 54 } // end namespace yaml 55 56 namespace SymbolRewriter { 57 58 /// The basic entity representing a rewrite operation. It serves as the base 59 /// class for any rewrite descriptor. It has a certain set of specializations 60 /// which describe a particular rewrite. 61 /// 62 /// The RewriteMapParser can be used to parse a mapping file that provides the 63 /// mapping for rewriting the symbols. The descriptors individually describe 64 /// whether to rewrite a function, global variable, or global alias. Each of 65 /// these can be selected either by explicitly providing a name for the ones to 66 /// be rewritten or providing a (posix compatible) regular expression that will 67 /// select the symbols to rewrite. This descriptor list is passed to the 68 /// SymbolRewriter pass. 69 class RewriteDescriptor { 70 public: 71 enum class Type { 72 Invalid, /// invalid 73 Function, /// function - descriptor rewrites a function 74 GlobalVariable, /// global variable - descriptor rewrites a global variable 75 NamedAlias, /// named alias - descriptor rewrites a global alias 76 }; 77 78 RewriteDescriptor(const RewriteDescriptor &) = delete; 79 RewriteDescriptor &operator=(const RewriteDescriptor &) = delete; 80 virtual ~RewriteDescriptor() = default; 81 82 Type getType() const { return Kind; } 83 84 virtual bool performOnModule(Module &M) = 0; 85 86 protected: 87 explicit RewriteDescriptor(Type T) : Kind(T) {} 88 89 private: 90 const Type Kind; 91 }; 92 93 using RewriteDescriptorList = std::list<std::unique_ptr<RewriteDescriptor>>; 94 95 class RewriteMapParser { 96 public: 97 bool parse(const std::string &MapFile, RewriteDescriptorList *Descriptors); 98 99 private: 100 bool parse(std::unique_ptr<MemoryBuffer> &MapFile, RewriteDescriptorList *DL); 101 bool parseEntry(yaml::Stream &Stream, yaml::KeyValueNode &Entry, 102 RewriteDescriptorList *DL); 103 bool parseRewriteFunctionDescriptor(yaml::Stream &Stream, 104 yaml::ScalarNode *Key, 105 yaml::MappingNode *Value, 106 RewriteDescriptorList *DL); 107 bool parseRewriteGlobalVariableDescriptor(yaml::Stream &Stream, 108 yaml::ScalarNode *Key, 109 yaml::MappingNode *Value, 110 RewriteDescriptorList *DL); 111 bool parseRewriteGlobalAliasDescriptor(yaml::Stream &YS, yaml::ScalarNode *K, 112 yaml::MappingNode *V, 113 RewriteDescriptorList *DL); 114 }; 115 116 } // end namespace SymbolRewriter 117 118 ModulePass *createRewriteSymbolsPass(); 119 ModulePass *createRewriteSymbolsPass(SymbolRewriter::RewriteDescriptorList &); 120 121 class RewriteSymbolPass : public PassInfoMixin<RewriteSymbolPass> { 122 public: 123 RewriteSymbolPass() { loadAndParseMapFiles(); } 124 125 RewriteSymbolPass(SymbolRewriter::RewriteDescriptorList &DL) { 126 Descriptors.splice(Descriptors.begin(), DL); 127 } 128 129 PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM); 130 131 // Glue for old PM 132 bool runImpl(Module &M); 133 134 private: 135 void loadAndParseMapFiles(); 136 137 SymbolRewriter::RewriteDescriptorList Descriptors; 138 }; 139 140 } // end namespace llvm 141 142 #endif //LLVM_TRANSFORMS_UTILS_SYMBOLREWRITER_H 143
