lib/CodeGen/AsmPrinter/DIEHash.h

   1 //===-- llvm/CodeGen/DIEHash.h - Dwarf Hashing Framework -------*- 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 contains support for DWARF4 hashing of DIEs.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #ifndef LLVM_LIB_CODEGEN_ASMPRINTER_DIEHASH_H
  14 #define LLVM_LIB_CODEGEN_ASMPRINTER_DIEHASH_H
  15
  16 #include "llvm/ADT/DenseMap.h"
  17 #include "llvm/CodeGen/DIE.h"
  18 #include "llvm/Support/MD5.h"
  19
  20 namespace llvm {
  21
  22 class AsmPrinter;
  23 class CompileUnit;
  24
  25 /// An object containing the capability of hashing and adding hash
  26 /// attributes onto a DIE.
  27 class DIEHash {
  28   // Collection of all attributes used in hashing a particular DIE.
  29   struct DIEAttrs {
  30 #define HANDLE_DIE_HASH_ATTR(NAME) DIEValue NAME;
  31 #include "DIEHashAttributes.def"
  32   };
  33
  34 public:
  35   DIEHash(AsmPrinter *A = nullptr) : AP(A) {}
  36
  37   /// Computes the CU signature.
  38   uint64_t computeCUSignature(StringRef DWOName, const DIE &Die);
  39
  40   /// Computes the type signature.
  41   uint64_t computeTypeSignature(const DIE &Die);
  42
  43   // Helper routines to process parts of a DIE.
  44 private:
  45   /// Adds the parent context of \param Parent to the hash.
  46   void addParentContext(const DIE &Parent);
  47
  48   /// Adds the attributes of \param Die to the hash.
  49   void addAttributes(const DIE &Die);
  50
  51   /// Computes the full DWARF4 7.27 hash of the DIE.
  52   void computeHash(const DIE &Die);
  53
  54   // Routines that add DIEValues to the hash.
  55 public:
  56   /// Adds \param Value to the hash.
  57   void update(uint8_t Value) { Hash.update(Value); }
  58
  59   /// Encodes and adds \param Value to the hash as a ULEB128.
  60   void addULEB128(uint64_t Value);
  61
  62   /// Encodes and adds \param Value to the hash as a SLEB128.
  63   void addSLEB128(int64_t Value);
  64
  65 private:
  66   /// Adds \param Str to the hash and includes a NULL byte.
  67   void addString(StringRef Str);
  68
  69   /// Collects the attributes of DIE \param Die into the \param Attrs
  70   /// structure.
  71   void collectAttributes(const DIE &Die, DIEAttrs &Attrs);
  72
  73   /// Hashes the attributes in \param Attrs in order.
  74   void hashAttributes(const DIEAttrs &Attrs, dwarf::Tag Tag);
  75
  76   /// Hashes the data in a block like DIEValue, e.g. DW_FORM_block or
  77   /// DW_FORM_exprloc.
  78   void hashBlockData(const DIE::const_value_range &Values);
  79
  80   /// Hashes the contents pointed to in the .debug_loc section.
  81   void hashLocList(const DIELocList &LocList);
  82
  83   /// Hashes an individual attribute.
  84   void hashAttribute(const DIEValue &Value, dwarf::Tag Tag);
  85
  86   /// Hashes an attribute that refers to another DIE.
  87   void hashDIEEntry(dwarf::Attribute Attribute, dwarf::Tag Tag,
  88                     const DIE &Entry);
  89
  90   /// Hashes a reference to a named type in such a way that is
  91   /// independent of whether that type is described by a declaration or a
  92   /// definition.
  93   void hashShallowTypeReference(dwarf::Attribute Attribute, const DIE &Entry,
  94                                 StringRef Name);
  95
  96   /// Hashes a reference to a previously referenced type DIE.
  97   void hashRepeatedTypeReference(dwarf::Attribute Attribute,
  98                                  unsigned DieNumber);
  99
 100   void hashNestedType(const DIE &Die, StringRef Name);
 101
 102 private:
 103   MD5 Hash;
 104   AsmPrinter *AP;
 105   DenseMap<const DIE *, unsigned> Numbering;
 106 };
 107 }
 108
 109 #endif