1 //===- RemarkLinker.cpp ---------------------------------------------------===//
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 an implementation of the remark linker.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "llvm/Remarks/RemarkLinker.h"
14 #include "llvm/ADT/StringRef.h"
15 #include "llvm/Object/ObjectFile.h"
16 #include "llvm/Object/SymbolicFile.h"
17 #include "llvm/Remarks/RemarkParser.h"
18 #include "llvm/Remarks/RemarkSerializer.h"
19 #include "llvm/Support/Error.h"
20 #include <optional>
21 
22 using namespace llvm;
23 using namespace llvm::remarks;
24 
25 namespace llvm {
26 class raw_ostream;
27 }
28 
29 static Expected<StringRef>
30 getRemarksSectionName(const object::ObjectFile &Obj) {
31   if (Obj.isMachO())
32     return StringRef("__remarks");
33   // ELF -> .remarks, but there is no ELF support at this point.
34   return createStringError(std::errc::illegal_byte_sequence,
35                            "Unsupported file format.");
36 }
37 
38 Expected<std::optional<StringRef>>
39 llvm::remarks::getRemarksSectionContents(const object::ObjectFile &Obj) {
40   Expected<StringRef> SectionName = getRemarksSectionName(Obj);
41   if (!SectionName)
42     return SectionName.takeError();
43 
44   for (const object::SectionRef &Section : Obj.sections()) {
45     Expected<StringRef> MaybeName = Section.getName();
46     if (!MaybeName)
47       return MaybeName.takeError();
48     if (*MaybeName != *SectionName)
49       continue;
50 
51     if (Expected<StringRef> Contents = Section.getContents())
52       return *Contents;
53     else
54       return Contents.takeError();
55   }
56   return std::optional<StringRef>{};
57 }
58 
59 Remark &RemarkLinker::keep(std::unique_ptr<Remark> Remark) {
60   StrTab.internalize(*Remark);
61   auto Inserted = Remarks.insert(std::move(Remark));
62   return **Inserted.first;
63 }
64 
65 void RemarkLinker::setExternalFilePrependPath(StringRef PrependPathIn) {
66   PrependPath = std::string(PrependPathIn);
67 }
68 
69 Error RemarkLinker::link(StringRef Buffer, std::optional<Format> RemarkFormat) {
70   if (!RemarkFormat) {
71     Expected<Format> ParserFormat = magicToFormat(Buffer);
72     if (!ParserFormat)
73       return ParserFormat.takeError();
74     RemarkFormat = *ParserFormat;
75   }
76 
77   Expected<std::unique_ptr<RemarkParser>> MaybeParser =
78       createRemarkParserFromMeta(
79           *RemarkFormat, Buffer, /*StrTab=*/std::nullopt,
80           PrependPath ? std::optional<StringRef>(StringRef(*PrependPath))
81                       : std::optional<StringRef>());
82   if (!MaybeParser)
83     return MaybeParser.takeError();
84 
85   RemarkParser &Parser = **MaybeParser;
86 
87   while (true) {
88     Expected<std::unique_ptr<Remark>> Next = Parser.next();
89     if (Error E = Next.takeError()) {
90       if (E.isA<EndOfFileError>()) {
91         consumeError(std::move(E));
92         break;
93       }
94       return E;
95     }
96 
97     assert(*Next != nullptr);
98 
99     if (shouldKeepRemark(**Next))
100       keep(std::move(*Next));
101   }
102   return Error::success();
103 }
104 
105 Error RemarkLinker::link(const object::ObjectFile &Obj,
106                          std::optional<Format> RemarkFormat) {
107   Expected<std::optional<StringRef>> SectionOrErr =
108       getRemarksSectionContents(Obj);
109   if (!SectionOrErr)
110     return SectionOrErr.takeError();
111 
112   if (std::optional<StringRef> Section = *SectionOrErr)
113     return link(*Section, RemarkFormat);
114   return Error::success();
115 }
116 
117 Error RemarkLinker::serialize(raw_ostream &OS, Format RemarksFormat) const {
118   Expected<std::unique_ptr<RemarkSerializer>> MaybeSerializer =
119       createRemarkSerializer(RemarksFormat, SerializerMode::Standalone, OS,
120                              std::move(const_cast<StringTable &>(StrTab)));
121   if (!MaybeSerializer)
122     return MaybeSerializer.takeError();
123 
124   std::unique_ptr<remarks::RemarkSerializer> Serializer =
125       std::move(*MaybeSerializer);
126 
127   for (const Remark &R : remarks())
128     Serializer->emit(R);
129   return Error::success();
130 }
131