lib/CodeGen/AsmPrinter/DebugLocStream.h

   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
  16 namespace llvm {
  17
  18 class AsmPrinter;
  19 class DbgVariable;
  20 class DwarfCompileUnit;
  21 class MachineInstr;
  22 class 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?
  31 class DebugLocStream {
  32 public:
  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
  47 private:
  48   SmallVector<List, 4> Lists;
  49   SmallVector<Entry, 32> Entries;
  50   SmallString<256> DWARFBytes;
  51   SmallVector<std::string, 32> Comments;
  52
  53   /// Only verbose textual output needs comments.  This will be set to
  54   /// true for that case, and false otherwise.
  55   bool GenerateComments;
  56
  57 public:
  58   DebugLocStream(bool GenerateComments) : GenerateComments(GenerateComments) { }
  59   size_t getNumLists() const { return Lists.size(); }
  60   const List &getList(size_t LI) const { return Lists[LI]; }
  61   ArrayRef<List> getLists() const { return Lists; }
  62
  63   class ListBuilder;
  64   class EntryBuilder;
  65
  66 private:
  67   /// Start a new .debug_loc entry list.
  68   ///
  69   /// Start a new .debug_loc entry list.  Return the new list's index so it can
  70   /// be retrieved later via \a getList().
  71   ///
  72   /// Until the next call, \a startEntry() will add entries to this list.
  73   size_t startList(DwarfCompileUnit *CU) {
  74     size_t LI = Lists.size();
  75     Lists.emplace_back(CU, Entries.size());
  76     return LI;
  77   }
  78
  79   /// Finalize a .debug_loc entry list.
  80   ///
  81   /// If there are no entries in this list, delete it outright.  Otherwise,
  82   /// create a label with \a Asm.
  83   ///
  84   /// \return false iff the list is deleted.
  85   bool finalizeList(AsmPrinter &Asm);
  86
  87   /// Start a new .debug_loc entry.
  88   ///
  89   /// Until the next call, bytes added to the stream will be added to this
  90   /// entry.
  91   void startEntry(const MCSymbol *BeginSym, const MCSymbol *EndSym) {
  92     Entries.push_back({BeginSym, EndSym, DWARFBytes.size(), Comments.size()});
  93   }
  94
  95   /// Finalize a .debug_loc entry, deleting if it's empty.
  96   void finalizeEntry();
  97
  98 public:
  99   BufferByteStreamer getStreamer() {
 100     return BufferByteStreamer(DWARFBytes, Comments, GenerateComments);
 101   }
 102
 103   ArrayRef<Entry> getEntries(const List &L) const {
 104     size_t LI = getIndex(L);
 105     return makeArrayRef(Entries)
 106         .slice(Lists[LI].EntryOffset, getNumEntries(LI));
 107   }
 108
 109   ArrayRef<char> getBytes(const Entry &E) const {
 110     size_t EI = getIndex(E);
 111     return makeArrayRef(DWARFBytes.begin(), DWARFBytes.end())
 112         .slice(Entries[EI].ByteOffset, getNumBytes(EI));
 113   }
 114   ArrayRef<std::string> getComments(const Entry &E) const {
 115     size_t EI = getIndex(E);
 116     return makeArrayRef(Comments)
 117         .slice(Entries[EI].CommentOffset, getNumComments(EI));
 118   }
 119
 120 private:
 121   size_t getIndex(const List &L) const {
 122     assert(&Lists.front() <= &L && &L <= &Lists.back() &&
 123            "Expected valid list");
 124     return &L - &Lists.front();
 125   }
 126   size_t getIndex(const Entry &E) const {
 127     assert(&Entries.front() <= &E && &E <= &Entries.back() &&
 128            "Expected valid entry");
 129     return &E - &Entries.front();
 130   }
 131   size_t getNumEntries(size_t LI) const {
 132     if (LI + 1 == Lists.size())
 133       return Entries.size() - Lists[LI].EntryOffset;
 134     return Lists[LI + 1].EntryOffset - Lists[LI].EntryOffset;
 135   }
 136   size_t getNumBytes(size_t EI) const {
 137     if (EI + 1 == Entries.size())
 138       return DWARFBytes.size() - Entries[EI].ByteOffset;
 139     return Entries[EI + 1].ByteOffset - Entries[EI].ByteOffset;
 140   }
 141   size_t getNumComments(size_t EI) const {
 142     if (EI + 1 == Entries.size())
 143       return Comments.size() - Entries[EI].CommentOffset;
 144     return Entries[EI + 1].CommentOffset - Entries[EI].CommentOffset;
 145   }
 146 };
 147
 148 /// Builder for DebugLocStream lists.
 149 class DebugLocStream::ListBuilder {
 150   DebugLocStream &Locs;
 151   AsmPrinter &Asm;
 152   DbgVariable &V;
 153   const MachineInstr &MI;
 154   size_t ListIndex;
 155
 156 public:
 157   ListBuilder(DebugLocStream &Locs, DwarfCompileUnit &CU, AsmPrinter &Asm,
 158               DbgVariable &V, const MachineInstr &MI)
 159       : Locs(Locs), Asm(Asm), V(V), MI(MI), ListIndex(Locs.startList(&CU)) {}
 160
 161   /// Finalize the list.
 162   ///
 163   /// If the list is empty, delete it.  Otherwise, finalize it by creating a
 164   /// temp symbol in \a Asm and setting up the \a DbgVariable.
 165   ~ListBuilder();
 166
 167   DebugLocStream &getLocs() { return Locs; }
 168 };
 169
 170 /// Builder for DebugLocStream entries.
 171 class DebugLocStream::EntryBuilder {
 172   DebugLocStream &Locs;
 173
 174 public:
 175   EntryBuilder(ListBuilder &List, const MCSymbol *Begin, const MCSymbol *End)
 176       : Locs(List.getLocs()) {
 177     Locs.startEntry(Begin, End);
 178   }
 179
 180   /// Finalize the entry, deleting it if it's empty.
 181   ~EntryBuilder() { Locs.finalizeEntry(); }
 182
 183   BufferByteStreamer getStreamer() { return Locs.getStreamer(); }
 184 };
 185
 186 } // namespace llvm
 187
 188 #endif