1 //===- TpiHashing.cpp -----------------------------------------------------===//
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 #include "llvm/DebugInfo/PDB/Native/TpiHashing.h"
11 
12 #include "llvm/DebugInfo/CodeView/TypeDeserializer.h"
13 #include "llvm/DebugInfo/PDB/Native/Hash.h"
14 #include "llvm/Support/JamCRC.h"
15 
16 using namespace llvm;
17 using namespace llvm::codeview;
18 using namespace llvm::pdb;
19 
20 // Corresponds to `fUDTAnon`.
21 static bool isAnonymous(StringRef Name) {
22   return Name == "<unnamed-tag>" || Name == "__unnamed" ||
23          Name.endswith("::<unnamed-tag>") || Name.endswith("::__unnamed");
24 }
25 
26 // Computes the hash for a user-defined type record. This could be a struct,
27 // class, union, or enum.
28 static uint32_t getHashForUdt(const TagRecord &Rec,
29                               ArrayRef<uint8_t> FullRecord) {
30   ClassOptions Opts = Rec.getOptions();
31   bool ForwardRef = bool(Opts & ClassOptions::ForwardReference);
32   bool Scoped = bool(Opts & ClassOptions::Scoped);
33   bool HasUniqueName = bool(Opts & ClassOptions::HasUniqueName);
34   bool IsAnon = HasUniqueName && isAnonymous(Rec.getName());
35 
36   if (!ForwardRef && !Scoped && !IsAnon)
37     return hashStringV1(Rec.getName());
38   if (!ForwardRef && HasUniqueName && !IsAnon)
39     return hashStringV1(Rec.getUniqueName());
40   return hashBufferV8(FullRecord);
41 }
42 
43 template <typename T>
44 static Expected<uint32_t> getHashForUdt(const CVType &Rec) {
45   T Deserialized;
46   if (auto E = TypeDeserializer::deserializeAs(const_cast<CVType &>(Rec),
47                                                Deserialized))
48     return std::move(E);
49   return getHashForUdt(Deserialized, Rec.data());
50 }
51 
52 template <typename T>
53 static Expected<uint32_t> getSourceLineHash(const CVType &Rec) {
54   T Deserialized;
55   if (auto E = TypeDeserializer::deserializeAs(const_cast<CVType &>(Rec),
56                                                Deserialized))
57     return std::move(E);
58   char Buf[4];
59   support::endian::write32le(Buf, Deserialized.getUDT().getIndex());
60   return hashStringV1(StringRef(Buf, 4));
61 }
62 
63 Expected<uint32_t> llvm::pdb::hashTypeRecord(const CVType &Rec) {
64   switch (Rec.kind()) {
65   case LF_CLASS:
66   case LF_STRUCTURE:
67   case LF_INTERFACE:
68     return getHashForUdt<ClassRecord>(Rec);
69   case LF_UNION:
70     return getHashForUdt<UnionRecord>(Rec);
71   case LF_ENUM:
72     return getHashForUdt<EnumRecord>(Rec);
73 
74   case LF_UDT_SRC_LINE:
75     return getSourceLineHash<UdtSourceLineRecord>(Rec);
76   case LF_UDT_MOD_SRC_LINE:
77     return getSourceLineHash<UdtModSourceLineRecord>(Rec);
78 
79   default:
80     break;
81   }
82 
83   // Run CRC32 over the bytes. This corresponds to `hashBufv8`.
84   JamCRC JC(/*Init=*/0U);
85   ArrayRef<char> Bytes(reinterpret_cast<const char *>(Rec.data().data()),
86                        Rec.data().size());
87   JC.update(Bytes);
88   return JC.getCRC();
89 }
90