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
20namespace llvm {
21
22class AsmPrinter;
23
24/// An object containing the capability of hashing and adding hash
25/// attributes onto a DIE.
26class DIEHash {
27  // Collection of all attributes used in hashing a particular DIE.
28  struct DIEAttrs {
29#define HANDLE_DIE_HASH_ATTR(NAME) DIEValue NAME;
30#include "DIEHashAttributes.def"
31  };
32
33public:
34  DIEHash(AsmPrinter *A = nullptr, DwarfCompileUnit *CU = nullptr)
35      : AP(A), CU(CU) {}
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.
44private:
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.
55public:
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  void hashRawTypeReference(const DIE &Entry);
66
67private:
68  /// Adds \param Str to the hash and includes a NULL byte.
69  void addString(StringRef Str);
70
71  /// Collects the attributes of DIE \param Die into the \param Attrs
72  /// structure.
73  void collectAttributes(const DIE &Die, DIEAttrs &Attrs);
74
75  /// Hashes the attributes in \param Attrs in order.
76  void hashAttributes(const DIEAttrs &Attrs, dwarf::Tag Tag);
77
78  /// Hashes the data in a block like DIEValue, e.g. DW_FORM_block or
79  /// DW_FORM_exprloc.
80  void hashBlockData(const DIE::const_value_range &Values);
81
82  /// Hashes the contents pointed to in the .debug_loc section.
83  void hashLocList(const DIELocList &LocList);
84
85  /// Hashes an individual attribute.
86  void hashAttribute(const DIEValue &Value, dwarf::Tag Tag);
87
88  /// Hashes an attribute that refers to another DIE.
89  void hashDIEEntry(dwarf::Attribute Attribute, dwarf::Tag Tag,
90                    const DIE &Entry);
91
92  /// Hashes a reference to a named type in such a way that is
93  /// independent of whether that type is described by a declaration or a
94  /// definition.
95  void hashShallowTypeReference(dwarf::Attribute Attribute, const DIE &Entry,
96                                StringRef Name);
97
98  /// Hashes a reference to a previously referenced type DIE.
99  void hashRepeatedTypeReference(dwarf::Attribute Attribute,
100                                 unsigned DieNumber);
101
102  void hashNestedType(const DIE &Die, StringRef Name);
103
104private:
105  MD5 Hash;
106  AsmPrinter *AP;
107  DwarfCompileUnit *CU;
108  DenseMap<const DIE *, unsigned> Numbering;
109};
110}
111
112#endif
113