1 files changed, 130 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfStringPool.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfStringPool.cpp
new file mode 100644
index 000000000000..2a76dcb1b082
--- /dev/null
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfStringPool.cpp
@@ -0,0 +1,130 @@
+//===- llvm/CodeGen/DwarfStringPool.cpp - Dwarf Debug Framework -----------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "DwarfStringPool.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/Twine.h"
+#include "llvm/CodeGen/AsmPrinter.h"
+#include "llvm/MC/MCAsmInfo.h"
+#include "llvm/MC/MCStreamer.h"
+#include <cassert>
+#include <utility>
+
+using namespace llvm;
+
+DwarfStringPool::DwarfStringPool(BumpPtrAllocator &A, AsmPrinter &Asm,
+                                 StringRef Prefix)
+    : Pool(A), Prefix(Prefix),
+      ShouldCreateSymbols(Asm.MAI->doesDwarfUseRelocationsAcrossSections()) {}
+
+StringMapEntry<DwarfStringPool::EntryTy> &
+DwarfStringPool::getEntryImpl(AsmPrinter &Asm, StringRef Str) {
+  auto I = Pool.insert(std::make_pair(Str, EntryTy()));
+  auto &Entry = I.first->second;
+  if (I.second) {
+    Entry.Index = EntryTy::NotIndexed;
+    Entry.Offset = NumBytes;
+    Entry.Symbol = ShouldCreateSymbols ? Asm.createTempSymbol(Prefix) : nullptr;
+
+    NumBytes += Str.size() + 1;
+    assert(NumBytes > Entry.Offset && "Unexpected overflow");
+  }
+  return *I.first;
+}
+
+DwarfStringPool::EntryRef DwarfStringPool::getEntry(AsmPrinter &Asm,
+                                                    StringRef Str) {
+  auto &MapEntry = getEntryImpl(Asm, Str);
+  return EntryRef(MapEntry, false);
+}
+
+DwarfStringPool::EntryRef DwarfStringPool::getIndexedEntry(AsmPrinter &Asm,
+                                                           StringRef Str) {
+  auto &MapEntry = getEntryImpl(Asm, Str);
+  if (!MapEntry.getValue().isIndexed())
+    MapEntry.getValue().Index = NumIndexedStrings++;
+  return EntryRef(MapEntry, true);
+}
+
+void DwarfStringPool::emitStringOffsetsTableHeader(AsmPrinter &Asm,
+                                                   MCSection *Section,
+                                                   MCSymbol *StartSym) {
+  if (getNumIndexedStrings() == 0)
+    return;
+  Asm.OutStreamer->SwitchSection(Section);
+  unsigned EntrySize = 4;
+  // FIXME: DWARF64
+  // We are emitting the header for a contribution to the string offsets
+  // table. The header consists of an entry with the contribution's
+  // size (not including the size of the length field), the DWARF version and
+  // 2 bytes of padding.
+  Asm.emitInt32(getNumIndexedStrings() * EntrySize + 4);
+  Asm.emitInt16(Asm.getDwarfVersion());
+  Asm.emitInt16(0);
+  // Define the symbol that marks the start of the contribution. It is
+  // referenced by most unit headers via DW_AT_str_offsets_base.
+  // Split units do not use the attribute.
+  if (StartSym)
+    Asm.OutStreamer->EmitLabel(StartSym);
+}
+
+void DwarfStringPool::emit(AsmPrinter &Asm, MCSection *StrSection,
+                           MCSection *OffsetSection, bool UseRelativeOffsets) {
+  if (Pool.empty())
+    return;
+
+  // Start the dwarf str section.
+  Asm.OutStreamer->SwitchSection(StrSection);
+
+  // Get all of the string pool entries and sort them by their offset.
+  SmallVector<const StringMapEntry<EntryTy> *, 64> Entries;
+  Entries.reserve(Pool.size());
+
+  for (const auto &E : Pool)
+    Entries.push_back(&E);
+
+  llvm::sort(Entries, [](const StringMapEntry<EntryTy> *A,
+                         const StringMapEntry<EntryTy> *B) {
+    return A->getValue().Offset < B->getValue().Offset;
+  });
+
+  for (const auto &Entry : Entries) {
+    assert(ShouldCreateSymbols == static_cast<bool>(Entry->getValue().Symbol) &&
+           "Mismatch between setting and entry");
+
+    // Emit a label for reference from debug information entries.
+    if (ShouldCreateSymbols)
+      Asm.OutStreamer->EmitLabel(Entry->getValue().Symbol);
+
+    // Emit the string itself with a terminating null byte.
+    Asm.OutStreamer->AddComment("string offset=" +
+                                Twine(Entry->getValue().Offset));
+    Asm.OutStreamer->EmitBytes(
+        StringRef(Entry->getKeyData(), Entry->getKeyLength() + 1));
+  }
+
+  // If we've got an offset section go ahead and emit that now as well.
+  if (OffsetSection) {
+    // Now only take the indexed entries and put them in an array by their ID so
+    // we can emit them in order.
+    Entries.resize(NumIndexedStrings);
+    for (const auto &Entry : Pool) {
+      if (Entry.getValue().isIndexed())
+        Entries[Entry.getValue().Index] = &Entry;
+    }
+
+    Asm.OutStreamer->SwitchSection(OffsetSection);
+    unsigned size = 4; // FIXME: DWARF64 is 8.
+    for (const auto &Entry : Entries)
+      if (UseRelativeOffsets)
+        Asm.emitDwarfStringOffset(Entry->getValue());
+      else
+        Asm.OutStreamer->EmitIntValue(Entry->getValue().Offset, size);
+  }
+}