Encapsulate the DWARF string pool in a separate type.

Pulls out some more code from some of the rather monolithic DWARF
classes. Unlike the address table, the string table won't move up into
DwarfDebug - each DWARF file has its own string table (but there can be
only one address table).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207277 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/AsmPrinter/DwarfStringPool.cpp

@@ -0,0 +1,74 @@
+//===-- llvm/CodeGen/DwarfStringPool.cpp - Dwarf Debug Framework ----------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "DwarfStringPool.h"
+#include "llvm/MC/MCStreamer.h"
+
+using namespace llvm;
+
+MCSymbol *DwarfStringPool::getSectionSymbol() { return SectionSymbol; }
+
+std::pair<MCSymbol *, unsigned> &
+getEntry(AsmPrinter &Asm,
+         StringMap<std::pair<MCSymbol *, unsigned>, BumpPtrAllocator &> &Pool,
+         StringRef Prefix, StringRef Str) {
+  std::pair<MCSymbol *, unsigned> &Entry =
+      Pool.GetOrCreateValue(Str).getValue();
+  if (!Entry.first) {
+    Entry.second = Pool.size() - 1;
+    Entry.first = Asm.GetTempSymbol(Prefix, Entry.second);
+  }
+  return Entry;
+}
+
+MCSymbol *DwarfStringPool::getSymbol(AsmPrinter &Asm, StringRef Str) {
+  return getEntry(Asm, Pool, Prefix, Str).first;
+}
+
+unsigned DwarfStringPool::getIndex(AsmPrinter &Asm, StringRef Str) {
+  return getEntry(Asm, Pool, Prefix, Str).second;
+}
+
+void DwarfStringPool::emit(AsmPrinter &Asm, const MCSection *StrSection,
+                           const MCSection *OffsetSection,
+                           const MCSymbol *StrSecSym) {
+  if (Pool.empty())
+    return;
+
+  // Start the dwarf str section.
+  Asm.OutStreamer.SwitchSection(StrSection);
+
+  // Get all of the string pool entries and put them in an array by their ID so
+  // we can sort them.
+  SmallVector<const StringMapEntry<std::pair<MCSymbol *, unsigned>> *, 64>
+  Entries(Pool.size());
+
+  for (const auto &E : Pool)
+    Entries[E.getValue().second] = &E;
+
+  for (const auto &Entry : Entries) {
+    // Emit a label for reference from debug information entries.
+    Asm.OutStreamer.EmitLabel(Entry->getValue().first);
+
+    // Emit the string itself with a terminating null byte.
+    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) {
+    Asm.OutStreamer.SwitchSection(OffsetSection);
+    unsigned offset = 0;
+    unsigned size = 4; // FIXME: DWARF64 is 8.
+    for (const auto &Entry : Entries) {
+      Asm.OutStreamer.EmitIntValue(offset, size);
+      offset += Entry->getKeyLength() + 1;
+    }
+  }
+}