1//===--- lib/CodeGen/DebugLocStream.h - DWARF debug_loc stream --*- 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#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_DEBUGLOCSTREAM_H
10#define LLVM_LIB_CODEGEN_ASMPRINTER_DEBUGLOCSTREAM_H
11
12#include "ByteStreamer.h"
13#include "llvm/ADT/ArrayRef.h"
14#include "llvm/ADT/SmallVector.h"
15
16namespace llvm {
17
18class AsmPrinter;
19class DbgVariable;
20class DwarfCompileUnit;
21class MachineInstr;
22class MCSymbol;
23
24/// Byte stream of .debug_loc entries.
25///
26/// Stores a unified stream of .debug_loc entries.  There's \a List for each
27/// variable/inlined-at pair, and an \a Entry for each \a DebugLocEntry.
28///
29/// FIXME: Do we need all these temp symbols?
30/// FIXME: Why not output directly to the output stream?
31class DebugLocStream {
32public:
33  struct List {
34    DwarfCompileUnit *CU;
35    MCSymbol *Label = nullptr;
36    size_t EntryOffset;
37    List(DwarfCompileUnit *CU, size_t EntryOffset)
38        : CU(CU), EntryOffset(EntryOffset) {}
39  };
40  struct Entry {
41    const MCSymbol *Begin;
42    const MCSymbol *End;
43    size_t ByteOffset;
44    size_t CommentOffset;
45  };
46
47private:
48  SmallVector<List, 4> Lists;
49  SmallVector<Entry, 32> Entries;
50  SmallString<256> DWARFBytes;
51  std::vector<std::string> Comments;
52  MCSymbol *Sym;
53
54  /// Only verbose textual output needs comments.  This will be set to
55  /// true for that case, and false otherwise.
56  bool GenerateComments;
57
58public:
59  DebugLocStream(bool GenerateComments) : GenerateComments(GenerateComments) { }
60  size_t getNumLists() const { return Lists.size(); }
61  const List &getList(size_t LI) const { return Lists[LI]; }
62  ArrayRef<List> getLists() const { return Lists; }
63  MCSymbol *getSym() const {
64    return Sym;
65  }
66  void setSym(MCSymbol *Sym) {
67    this->Sym = Sym;
68  }
69
70  class ListBuilder;
71  class EntryBuilder;
72
73private:
74  /// Start a new .debug_loc entry list.
75  ///
76  /// Start a new .debug_loc entry list.  Return the new list's index so it can
77  /// be retrieved later via \a getList().
78  ///
79  /// Until the next call, \a startEntry() will add entries to this list.
80  size_t startList(DwarfCompileUnit *CU) {
81    size_t LI = Lists.size();
82    Lists.emplace_back(CU, Entries.size());
83    return LI;
84  }
85
86  /// Finalize a .debug_loc entry list.
87  ///
88  /// If there are no entries in this list, delete it outright.  Otherwise,
89  /// create a label with \a Asm.
90  ///
91  /// \return false iff the list is deleted.
92  bool finalizeList(AsmPrinter &Asm);
93
94  /// Start a new .debug_loc entry.
95  ///
96  /// Until the next call, bytes added to the stream will be added to this
97  /// entry.
98  void startEntry(const MCSymbol *BeginSym, const MCSymbol *EndSym) {
99    Entries.push_back({BeginSym, EndSym, DWARFBytes.size(), Comments.size()});
100  }
101
102  /// Finalize a .debug_loc entry, deleting if it's empty.
103  void finalizeEntry();
104
105public:
106  BufferByteStreamer getStreamer() {
107    return BufferByteStreamer(DWARFBytes, Comments, GenerateComments);
108  }
109
110  ArrayRef<Entry> getEntries(const List &L) const {
111    size_t LI = getIndex(L);
112    return ArrayRef(Entries).slice(Lists[LI].EntryOffset, getNumEntries(LI));
113  }
114
115  ArrayRef<char> getBytes(const Entry &E) const {
116    size_t EI = getIndex(E);
117    return ArrayRef(DWARFBytes.begin(), DWARFBytes.end())
118        .slice(Entries[EI].ByteOffset, getNumBytes(EI));
119  }
120  ArrayRef<std::string> getComments(const Entry &E) const {
121    size_t EI = getIndex(E);
122    return ArrayRef(Comments).slice(Entries[EI].CommentOffset,
123                                    getNumComments(EI));
124  }
125
126private:
127  size_t getIndex(const List &L) const {
128    assert(&Lists.front() <= &L && &L <= &Lists.back() &&
129           "Expected valid list");
130    return &L - &Lists.front();
131  }
132  size_t getIndex(const Entry &E) const {
133    assert(&Entries.front() <= &E && &E <= &Entries.back() &&
134           "Expected valid entry");
135    return &E - &Entries.front();
136  }
137  size_t getNumEntries(size_t LI) const {
138    if (LI + 1 == Lists.size())
139      return Entries.size() - Lists[LI].EntryOffset;
140    return Lists[LI + 1].EntryOffset - Lists[LI].EntryOffset;
141  }
142  size_t getNumBytes(size_t EI) const {
143    if (EI + 1 == Entries.size())
144      return DWARFBytes.size() - Entries[EI].ByteOffset;
145    return Entries[EI + 1].ByteOffset - Entries[EI].ByteOffset;
146  }
147  size_t getNumComments(size_t EI) const {
148    if (EI + 1 == Entries.size())
149      return Comments.size() - Entries[EI].CommentOffset;
150    return Entries[EI + 1].CommentOffset - Entries[EI].CommentOffset;
151  }
152};
153
154/// Builder for DebugLocStream lists.
155class DebugLocStream::ListBuilder {
156  DebugLocStream &Locs;
157  AsmPrinter &Asm;
158  DbgVariable &V;
159  const MachineInstr &MI;
160  size_t ListIndex;
161  std::optional<uint8_t> TagOffset;
162
163public:
164  ListBuilder(DebugLocStream &Locs, DwarfCompileUnit &CU, AsmPrinter &Asm,
165              DbgVariable &V, const MachineInstr &MI)
166      : Locs(Locs), Asm(Asm), V(V), MI(MI), ListIndex(Locs.startList(&CU)),
167        TagOffset(std::nullopt) {}
168
169  void setTagOffset(uint8_t TO) {
170    TagOffset = TO;
171  }
172
173  /// Finalize the list.
174  ///
175  /// If the list is empty, delete it.  Otherwise, finalize it by creating a
176  /// temp symbol in \a Asm and setting up the \a DbgVariable.
177  ~ListBuilder();
178
179  DebugLocStream &getLocs() { return Locs; }
180};
181
182/// Builder for DebugLocStream entries.
183class DebugLocStream::EntryBuilder {
184  DebugLocStream &Locs;
185
186public:
187  EntryBuilder(ListBuilder &List, const MCSymbol *Begin, const MCSymbol *End)
188      : Locs(List.getLocs()) {
189    Locs.startEntry(Begin, End);
190  }
191
192  /// Finalize the entry, deleting it if it's empty.
193  ~EntryBuilder() { Locs.finalizeEntry(); }
194
195  BufferByteStreamer getStreamer() { return Locs.getStreamer(); }
196};
197
198} // namespace llvm
199
200#endif
201