include/llvm/Transforms/Utils/SymbolRewriter.h

   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