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