DebugInfo: Produce debug_{gnu_}pub{names,types} entries when explicitly requested, even in -gmlt or when empty

Turns out gold doesn't use the DW_AT_GNU_pubnames to decide whether to
parse the rest of the DIEs when building gdb-index. This causes gold to
trip over LLVM's output when there are DW_FORM_ref_addr present.

Gold does use the presence of a debug_gnu_pub{names,types} entry for the
CU to skip parsing the debug_info portion, so make sure that's included
even when empty (technically, when empty there couldn't be any ref_addr
anyway - it only came up when gmlt didn't produce any (even non-empty)
pubnames - but given what that reveals about gold's implementation, this
seems like a good thing to do for consistency).

llvm-svn: 303894

4 files changed, 27 insertions, 20 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index e172712cf88..04073b3aed6 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -760,7 +760,7 @@ void DwarfCompileUnit::emitHeader(bool UseOffsets) {
 /// addGlobalName - Add a new global name to the compile unit.
 void DwarfCompileUnit::addGlobalName(StringRef Name, const DIE &Die,
                                      const DIScope *Context) {
-  if (includeMinimalInlineScopes())
+  if (!DD->hasDwarfPubSections(includeMinimalInlineScopes()))
     return;
   std::string FullName = getParentContextString(Context) + Name.str();
   GlobalNames[FullName] = &Die;
@@ -768,7 +768,7 @@ void DwarfCompileUnit::addGlobalName(StringRef Name, const DIE &Die,
 
 void DwarfCompileUnit::addGlobalNameForTypeUnit(StringRef Name,
                                                 const DIScope *Context) {
-  if (includeMinimalInlineScopes())
+  if (!DD->hasDwarfPubSections(includeMinimalInlineScopes()))
     return;
   std::string FullName = getParentContextString(Context) + Name.str();
   // Insert, allowing the entry to remain as-is if it's already present
@@ -781,7 +781,7 @@ void DwarfCompileUnit::addGlobalNameForTypeUnit(StringRef Name,
 /// Add a new global type to the unit.
 void DwarfCompileUnit::addGlobalType(const DIType *Ty, const DIE &Die,
                                      const DIScope *Context) {
-  if (includeMinimalInlineScopes())
+  if (!DD->hasDwarfPubSections(includeMinimalInlineScopes()))
     return;
   std::string FullName = getParentContextString(Context) + Ty->getName().str();
   GlobalTypes[FullName] = &Die;
@@ -789,7 +789,7 @@ void DwarfCompileUnit::addGlobalType(const DIType *Ty, const DIE &Die,
 
 void DwarfCompileUnit::addGlobalTypeUnitType(const DIType *Ty,
                                              const DIScope *Context) {
-  if (includeMinimalInlineScopes())
+  if (!DD->hasDwarfPubSections(includeMinimalInlineScopes()))
     return;
   std::string FullName = getParentContextString(Context) + Ty->getName().str();
   // Insert, allowing the entry to remain as-is if it's already present
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
index 77e9e671529..b8f57472f17 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
@@ -77,8 +77,6 @@ class DwarfCompileUnit final : public DwarfUnit {
 
   bool isDwoUnit() const override;
 
-  bool includeMinimalInlineScopes() const;
-
   DenseMap<const MDNode *, DIE *> &getAbstractSPDies() {
     if (isDwoUnit() && !DD->shareAcrossDWOCUs())
       return AbstractSPDies;
@@ -101,6 +99,8 @@ public:
     return Skeleton;
   }
 
+  bool includeMinimalInlineScopes() const;
+
   void initStmtList();
 
   /// Apply the DW_AT_stmt_list from this compile unit to the specified DIE.
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 8fb3db274ec..fa59307896e 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -252,12 +252,6 @@ DwarfDebug::DwarfDebug(AsmPrinter *A, Module *M)
   // Handle split DWARF.
   HasSplitDwarf = !Asm->TM.Options.MCOptions.SplitDwarfFile.empty();
 
-  // Pubnames/pubtypes on by default for GDB.
-  if (DwarfPubSections == Default)
-    HasDwarfPubSections = tuneForGDB();
-  else
-    HasDwarfPubSections = DwarfPubSections == Enable;
-
   // SCE defaults to linkage names only for abstract subprograms.
   if (DwarfLinkageNames == DefaultLinkageNames)
     UseAllLinkageNames = !tuneForSCE();
@@ -391,8 +385,20 @@ void DwarfDebug::constructAbstractSubprogramScopeDIE(DwarfCompileUnit &SrcCU,
   }
 }
 
-void DwarfDebug::addGnuPubAttributes(DwarfUnit &U, DIE &D) const {
-  if (!GenerateGnuPubSections)
+bool DwarfDebug::hasDwarfPubSections(bool includeMinimalInlineScopes) const {
+  // Opting in to GNU Pubnames/types overrides the default to ensure these are
+  // generated for things like Gold's gdb_index generation.
+  if (GenerateGnuPubSections)
+    return true;
+
+  if (DwarfPubSections == Default)
+    return tuneForGDB() && !includeMinimalInlineScopes;
+
+  return DwarfPubSections == Enable;
+}
+
+void DwarfDebug::addGnuPubAttributes(DwarfCompileUnit &U, DIE &D) const {
+  if (!hasDwarfPubSections(U.includeMinimalInlineScopes()))
     return;
 
   U.addFlag(D, dwarf::DW_AT_GNU_pubnames);
@@ -718,7 +724,9 @@ void DwarfDebug::endModule() {
   }
 
   // Emit the pubnames and pubtypes sections if requested.
-  if (HasDwarfPubSections) {
+  // The condition is optimistically correct - any CU not using GMLT (&
+  // implicit/default pubnames state) might still have pubnames.
+  if (hasDwarfPubSections(/* gmlt */ false)) {
     emitDebugPubNames(GenerateGnuPubSections);
     emitDebugPubTypes(GenerateGnuPubSections);
   }
@@ -1395,7 +1403,7 @@ void DwarfDebug::emitDebugPubSection(
 
     const auto &Globals = (TheU->*Accessor)();
 
-    if (Globals.empty())
+    if (!hasDwarfPubSections(TheU->includeMinimalInlineScopes()))
       continue;
 
     if (auto *Skeleton = TheU->getSkeleton())
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
index b9c5aa9ffb2..97b96dd6e04 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -246,9 +246,6 @@ class DwarfDebug : public DebugHandlerBase {
       std::pair<std::unique_ptr<DwarfTypeUnit>, const DICompositeType *>, 1>
       TypeUnitsUnderConstruction;
 
-  /// Whether to emit the pubnames/pubtypes sections.
-  bool HasDwarfPubSections;
-
   /// Whether to use the GNU TLS opcode (instead of the standard opcode).
   bool UseGNUTLSOpcode;
 
@@ -415,7 +412,7 @@ class DwarfDebug : public DebugHandlerBase {
 
   /// Flags to let the linker know we have emitted new style pubnames. Only
   /// emit it here if we don't have a skeleton CU for split dwarf.
-  void addGnuPubAttributes(DwarfUnit &U, DIE &D) const;
+  void addGnuPubAttributes(DwarfCompileUnit &U, DIE &D) const;
 
   /// Create new DwarfCompileUnit for the given metadata node with tag
   /// DW_TAG_compile_unit.
@@ -556,6 +553,8 @@ public:
   /// A helper function to check whether the DIE for a given Scope is
   /// going to be null.
   bool isLexicalScopeDIENull(LexicalScope *Scope);
+
+  bool hasDwarfPubSections(bool includeMinimalInlineScopes) const;
 };
 } // End of namespace llvm