1//===-- llvm/CodeGen/DwarfStringPool.cpp - Dwarf Debug Framework ----------===//
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 "DwarfStringPool.h"
11#include "llvm/MC/MCStreamer.h"
12
13using namespace llvm;
14
15static std::pair<MCSymbol *, unsigned> &
16getEntry(AsmPrinter &Asm,
17         StringMap<std::pair<MCSymbol *, unsigned>, BumpPtrAllocator &> &Pool,
18         StringRef Prefix, StringRef Str) {
19  std::pair<MCSymbol *, unsigned> &Entry = Pool[Str];
20  if (!Entry.first) {
21    Entry.second = Pool.size() - 1;
22    Entry.first = Asm.createTempSymbol(Prefix);
23  }
24  return Entry;
25}
26
27MCSymbol *DwarfStringPool::getSymbol(AsmPrinter &Asm, StringRef Str) {
28  return getEntry(Asm, Pool, Prefix, Str).first;
29}
30
31unsigned DwarfStringPool::getIndex(AsmPrinter &Asm, StringRef Str) {
32  return getEntry(Asm, Pool, Prefix, Str).second;
33}
34
35void DwarfStringPool::emit(AsmPrinter &Asm, const MCSection *StrSection,
36                           const MCSection *OffsetSection) {
37  if (Pool.empty())
38    return;
39
40  // Start the dwarf str section.
41  Asm.OutStreamer.SwitchSection(StrSection);
42
43  // Get all of the string pool entries and put them in an array by their ID so
44  // we can sort them.
45  SmallVector<const StringMapEntry<std::pair<MCSymbol *, unsigned>> *, 64>
46  Entries(Pool.size());
47
48  for (const auto &E : Pool)
49    Entries[E.getValue().second] = &E;
50
51  for (const auto &Entry : Entries) {
52    // Emit a label for reference from debug information entries.
53    Asm.OutStreamer.EmitLabel(Entry->getValue().first);
54
55    // Emit the string itself with a terminating null byte.
56    Asm.OutStreamer.EmitBytes(
57        StringRef(Entry->getKeyData(), Entry->getKeyLength() + 1));
58  }
59
60  // If we've got an offset section go ahead and emit that now as well.
61  if (OffsetSection) {
62    Asm.OutStreamer.SwitchSection(OffsetSection);
63    unsigned offset = 0;
64    unsigned size = 4; // FIXME: DWARF64 is 8.
65    for (const auto &Entry : Entries) {
66      Asm.OutStreamer.EmitIntValue(offset, size);
67      offset += Entry->getKeyLength() + 1;
68    }
69  }
70}
71