Add support for separating strings for the split debug info DWARF5

proposal. This leaves the strings in the skeleton die as strp,
but in all dwo files they're accessed now via DW_FORM_GNU_str_index.

Add support for dumping these sections and modify the fission-cu.ll
testcase to have the correct strings and form. Fix a small bug
in the fixed form sizes routine that involved out of array accesses
for the table and add a FIXME in the extractFast routine to fix
this up.

llvm-svn: 171779

5 files changed, 63 insertions, 6 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DIE.cpp b/llvm/lib/CodeGen/AsmPrinter/DIE.cpp
index 32d6cb2c45c..f33f0f999d7 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DIE.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DIE.cpp
@@ -197,6 +197,7 @@ void DIEInteger::EmitValue(AsmPrinter *Asm, unsigned Form) const {
   case dwarf::DW_FORM_data4: Size = 4; break;
   case dwarf::DW_FORM_ref8:  // Fall thru
   case dwarf::DW_FORM_data8: Size = 8; break;
+  case dwarf::DW_FORM_GNU_str_index: Asm->EmitULEB128(Integer); return;
   case dwarf::DW_FORM_udata: Asm->EmitULEB128(Integer); return;
   case dwarf::DW_FORM_sdata: Asm->EmitSLEB128(Integer); return;
   case dwarf::DW_FORM_addr:
@@ -220,6 +221,7 @@ unsigned DIEInteger::SizeOf(AsmPrinter *AP, unsigned Form) const {
   case dwarf::DW_FORM_data4: return sizeof(int32_t);
   case dwarf::DW_FORM_ref8:  // Fall thru
   case dwarf::DW_FORM_data8: return sizeof(int64_t);
+  case dwarf::DW_FORM_GNU_str_index: return MCAsmInfo::getULEB128Size(Integer);
   case dwarf::DW_FORM_udata: return MCAsmInfo::getULEB128Size(Integer);
   case dwarf::DW_FORM_sdata: return MCAsmInfo::getSLEB128Size(Integer);
   case dwarf::DW_FORM_addr:  return AP->getDataLayout().getPointerSize();
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index 854d82c2c58..60d7cd3945a 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -128,6 +128,27 @@ void CompileUnit::addSInt(DIE *Die, unsigned Attribute,
 /// reference to the string pool instead of immediate strings so that DIEs have
 /// more predictable sizes.
 void CompileUnit::addString(DIE *Die, unsigned Attribute, StringRef String) {
+  if (!DD->useSplitDwarf()) {
+    MCSymbol *Symb = DU->getStringPoolEntry(String);
+    DIEValue *Value;
+    if (Asm->needsRelocationsForDwarfStringPool())
+      Value = new (DIEValueAllocator) DIELabel(Symb);
+    else {
+      MCSymbol *StringPool = DU->getStringPoolSym();
+      Value = new (DIEValueAllocator) DIEDelta(Symb, StringPool);
+    }
+    Die->addValue(Attribute, dwarf::DW_FORM_strp, Value);
+  } else {
+    unsigned idx = DU->getStringPoolIndex(String);
+    DIEValue *Value = new (DIEValueAllocator) DIEInteger(idx);
+    Die->addValue(Attribute, dwarf::DW_FORM_GNU_str_index, Value);
+  }
+}
+
+/// addLocalString - Add a string attribute data and value. This is guaranteed
+/// to be in the local string pool instead of indirected.
+void CompileUnit::addLocalString(DIE *Die, unsigned Attribute,
+                                 StringRef String) {
   MCSymbol *Symb = DU->getStringPoolEntry(String);
   DIEValue *Value;
   if (Asm->needsRelocationsForDwarfStringPool())
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
index 368234ba862..f210dcc03b5 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
@@ -198,6 +198,10 @@ public:
   ///
   void addString(DIE *Die, unsigned Attribute, const StringRef Str);
 
+  /// addLocalString - Add a string attribute data and value.
+  ///
+  void addLocalString(DIE *Die, unsigned Attribute, const StringRef Str);
+
   /// addLabel - Add a Dwarf label attribute data and value.
   ///
   void addLabel(DIE *Die, unsigned Attribute, unsigned Form,
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 321256a613c..11b853f17ba 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -228,6 +228,16 @@ MCSymbol *DwarfUnits::getStringPoolEntry(StringRef Str) {
   return Entry.first = Asm->GetTempSymbol(StringPref, Entry.second);
 }
 
+unsigned DwarfUnits::getStringPoolIndex(StringRef Str) {
+  std::pair<MCSymbol*, unsigned> &Entry =
+    StringPool->GetOrCreateValue(Str).getValue();
+  if (Entry.first) return Entry.second;
+
+  Entry.second = NextStringPoolNumber++;
+  Entry.first = Asm->GetTempSymbol(StringPref, Entry.second);
+  return Entry.second;
+}
+
 // Define a unique number for the abbreviation.
 //
 void DwarfUnits::assignAbbrevNumber(DIEAbbrev &Abbrev) {
@@ -2116,12 +2126,14 @@ void DwarfDebug::emitDebugPubTypes() {
 }
 
 // Emit strings into a string section.
-void DwarfUnits::emitStrings(const MCSection *Section) {
+void DwarfUnits::emitStrings(const MCSection *StrSection,
+                             const MCSection *OffsetSection = NULL,
+                             const MCSymbol *StrSecSym = NULL) {
 
   if (StringPool->empty()) return;
 
   // Start the dwarf str section.
-  Asm->OutStreamer.SwitchSection(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.
@@ -2144,6 +2156,17 @@ void DwarfUnits::emitStrings(const MCSection *Section) {
                                          Entries[i].second->getKeyLength()+1),
                                0/*addrspace*/);
   }
+
+  // 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;
+    for (unsigned i = 0, e = Entries.size(); i != e; ++i) {
+      Asm->OutStreamer.EmitIntValue(offset, size, 0);
+      offset += Entries[i].second->getKeyLength() + 1;
+    }
+  }
 }
 
 // Emit visible names into a debug str section.
@@ -2377,7 +2400,7 @@ CompileUnit *DwarfDebug::constructSkeletonCU(const MDNode *N) {
                                        DIUnit.getLanguage(), Die, Asm,
                                        this, &SkeletonHolder);
   // FIXME: This should be the .dwo file.
-  NewCU->addString(Die, dwarf::DW_AT_GNU_dwo_name, FN);
+  NewCU->addLocalString(Die, dwarf::DW_AT_GNU_dwo_name, FN);
 
   // FIXME: We also need DW_AT_addr_base and DW_AT_dwo_id.
 
@@ -2393,7 +2416,7 @@ CompileUnit *DwarfDebug::constructSkeletonCU(const MDNode *N) {
     NewCU->addUInt(Die, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4, 0);
 
   if (!CompilationDir.empty())
-    NewCU->addString(Die, dwarf::DW_AT_comp_dir, CompilationDir);
+    NewCU->addLocalString(Die, dwarf::DW_AT_comp_dir, CompilationDir);
 
   SkeletonHolder.addUnit(NewCU);
 
@@ -2458,5 +2481,8 @@ void DwarfDebug::emitDebugAbbrevDWO() {
 // sections.
 void DwarfDebug::emitDebugStrDWO() {
   assert(useSplitDwarf() && "No split dwarf?");
-  InfoHolder.emitStrings(Asm->getObjFileLowering().getDwarfStrDWOSection());
+  const MCSection *OffSec = Asm->getObjFileLowering().getDwarfStrOffDWOSection();
+  const MCSymbol *StrSym = DwarfStrSectionSym;
+  InfoHolder.emitStrings(Asm->getObjFileLowering().getDwarfStrDWOSection(),
+                         OffSec, StrSym);
 }
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
index 59e4890dec4..cc6c0f7e638 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -240,7 +240,7 @@ public:
                  const MCSymbol *);
 
   /// \brief Emit all of the strings to the section given.
-  void emitStrings(const MCSection *);
+  void emitStrings(const MCSection *, const MCSection *, const MCSymbol *);
 
   /// \brief Returns the entry into the start of the pool.
   MCSymbol *getStringPoolSym();
@@ -249,6 +249,10 @@ public:
   /// string text.
   MCSymbol *getStringPoolEntry(StringRef Str);
 
+  /// \brief Returns the index into the string pool with the given
+  /// string text.
+  unsigned getStringPoolIndex(StringRef Str);
+
   /// \brief Returns the string pool.
   StrPool *getStringPool() { return StringPool; }
 };