Add DwarfUnit::isDwoUnit and use it to generalize string creation

Currently we only need to emit skeleton strings into the CU header and
we do this by explicitly calling "addLocalString". With gmlt-in-fission,
we'll be emitting a bunch of other strings from other codepaths where
it's not statically known that these strings will be local or not.

Introduce a virtual function to indicate whether this unit is a DWO unit
or not (I'm not sure if we have a good term for this, the
opposite/alternative to 'skeleton' unit) and use that to generalize the
string emission logic so that strings can be correctly emitted in both
the skeleton and dwo unit when in split dwarf mode.

And to demonstrate that this works, switch the existing special callers
of addLocalString in the skeleton builder to addString - and they still
work. Yay.

llvm-svn: 221094

5 files changed, 34 insertions, 15 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index 485ea34dc5c..13b3fda9380 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -836,4 +836,8 @@ void DwarfCompileUnit::applySubprogramAttributesToDefinition(DISubprogram SP,
                                            DIBuilder::LineTablesOnly);
   addGlobalName(SP.getName(), SPDie, Context);
 }
+
+bool DwarfCompileUnit::isDwoUnit() const {
+  return DD->useSplitDwarf() && Skeleton;
+}
 } // end llvm namespace
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
index c7373b4a75b..b924d270420 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
@@ -53,6 +53,8 @@ class DwarfCompileUnit : public DwarfUnit {
   std::unique_ptr<DIE> constructVariableDIEImpl(const DbgVariable &DV,
                                                 bool Abstract);
 
+  bool isDwoUnit() const override;
+
 public:
   DwarfCompileUnit(unsigned UID, DICompileUnit Node, AsmPrinter *A,
                    DwarfDebug *DW, DwarfFile *DWU);
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 82b84e5247c..15ce6b97c40 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -362,6 +362,8 @@ DwarfCompileUnit &DwarfDebug::constructDwarfCompileUnit(DICompileUnit DIUnit) {
   DwarfCompileUnit &NewCU = *OwnedUnit;
   DIE &Die = NewCU.getUnitDie();
   InfoHolder.addUnit(std::move(OwnedUnit));
+  if (useSplitDwarf())
+    NewCU.setSkeleton(constructSkeletonCU(NewCU));
 
   // LTO with assembly output shares a single line table amongst multiple CUs.
   // To avoid the compilation directory being ambiguous, let the line table
@@ -398,11 +400,10 @@ DwarfCompileUnit &DwarfDebug::constructDwarfCompileUnit(DICompileUnit DIUnit) {
     NewCU.addUInt(Die, dwarf::DW_AT_APPLE_major_runtime_vers,
                   dwarf::DW_FORM_data1, RVer);
 
-  if (useSplitDwarf()) {
+  if (useSplitDwarf())
     NewCU.initSection(Asm->getObjFileLowering().getDwarfInfoDWOSection(),
                       DwarfInfoDWOSectionSym);
-    NewCU.setSkeleton(constructSkeletonCU(NewCU));
-  } else
+  else
     NewCU.initSection(Asm->getObjFileLowering().getDwarfInfoSection(),
                       DwarfInfoSectionSym);
 
@@ -2041,11 +2042,11 @@ void DwarfDebug::emitDebugRanges() {
 
 void DwarfDebug::initSkeletonUnit(const DwarfUnit &U, DIE &Die,
                                   std::unique_ptr<DwarfUnit> NewU) {
-  NewU->addLocalString(Die, dwarf::DW_AT_GNU_dwo_name,
+  NewU->addString(Die, dwarf::DW_AT_GNU_dwo_name,
                        U.getCUNode().getSplitDebugFilename());
 
   if (!CompilationDir.empty())
-    NewU->addLocalString(Die, dwarf::DW_AT_comp_dir, CompilationDir);
+    NewU->addString(Die, dwarf::DW_AT_comp_dir, CompilationDir);
 
   addGnuPubAttributes(*NewU, Die);
 
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
index b29b1631df1..1730b9b62ea 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
@@ -201,10 +201,14 @@ void DwarfUnit::addSInt(DIELoc &Die, Optional<dwarf::Form> Form,
 /// table.
 void DwarfUnit::addString(DIE &Die, dwarf::Attribute Attribute,
                           StringRef String) {
-
-  if (!DD->useSplitDwarf())
+  if (!isDwoUnit())
     return addLocalString(Die, Attribute, String);
 
+  addIndexedString(Die, Attribute, String);
+}
+
+void DwarfUnit::addIndexedString(DIE &Die, dwarf::Attribute Attribute,
+                                 StringRef String) {
   unsigned idx = DU->getStringPool().getIndex(*Asm, String);
   DIEValue *Value = new (DIEValueAllocator) DIEInteger(idx);
   DIEValue *Str = new (DIEValueAllocator) DIEString(Value, String);
@@ -1632,3 +1636,8 @@ void DwarfTypeUnit::emitHeader(const MCSymbol *ASectionSym) const {
                                 sizeof(Ty->getOffset()));
 }
 
+bool DwarfTypeUnit::isDwoUnit() const {
+  // Since there are no skeleton type units, all type units are dwo type units
+  // when split DWARF is being used.
+  return DD->useSplitDwarf();
+}
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
index 2c80c124a3e..ca10d1aa667 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
@@ -127,6 +127,12 @@ protected:
             DwarfDebug *DW, DwarfFile *DWU);
 
   void initSection(const MCSection *Section);
+
+  /// Add a string attribute data and value.
+  void addLocalString(DIE &Die, dwarf::Attribute Attribute, StringRef Str);
+
+  void addIndexedString(DIE &Die, dwarf::Attribute Attribute, StringRef Str);
+
 public:
   virtual ~DwarfUnit();
 
@@ -209,10 +215,6 @@ public:
   /// addString - Add a string attribute data and value.
   void addString(DIE &Die, dwarf::Attribute Attribute, StringRef Str);
 
-  /// addLocalString - Add a string attribute data and value.
-  void addLocalString(DIE &Die, dwarf::Attribute Attribute,
-                      StringRef Str);
-
   /// addLabel - Add a Dwarf label attribute data and value.
   void addLabel(DIE &Die, dwarf::Attribute Attribute, dwarf::Form Form,
                 const MCSymbol *Label);
@@ -412,15 +414,19 @@ private:
   /// If this is a named finished type then include it in the list of types for
   /// the accelerator tables.
   void updateAcceleratorTables(DIScope Context, DIType Ty, const DIE &TyDIE);
+
+  virtual bool isDwoUnit() const = 0;
 };
 
 class DwarfTypeUnit : public DwarfUnit {
-private:
   uint64_t TypeSignature;
   const DIE *Ty;
   DwarfCompileUnit &CU;
   MCDwarfDwoLineTable *SplitLineTable;
 
+  unsigned getOrCreateSourceID(StringRef File, StringRef Directory) override;
+  bool isDwoUnit() const override;
+
 public:
   DwarfTypeUnit(unsigned UID, DwarfCompileUnit &CU, AsmPrinter *A,
                 DwarfDebug *DW, DwarfFile *DWU,
@@ -438,9 +444,6 @@ public:
   }
   using DwarfUnit::initSection;
   DwarfCompileUnit &getCU() override { return CU; }
-
-protected:
-  unsigned getOrCreateSourceID(StringRef File, StringRef Directory) override;
 };
 } // end llvm namespace
 #endif