2 files changed, 30 insertions, 15 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 3ea4c1c2775..b6cd82afea1 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -374,7 +374,7 @@ void DwarfDebug::constructAbstractSubprogramScopeDIE(DwarfCompileUnit &SrcCU,
 
   // Find the subprogram's DwarfCompileUnit in the SPMap in case the subprogram
   // was inlined from another compile unit.
-  auto &CU = *CUMap.lookup(SP->getUnit());
+  auto &CU = getOrCreateDwarfCompileUnit(SP->getUnit());
   if (auto *SkelCU = CU.getSkeleton()) {
     (shareAcrossDWOCUs() ? CU : SrcCU)
         .constructAbstractSubprogramScopeDIE(Scope);
@@ -407,7 +407,9 @@ void DwarfDebug::addGnuPubAttributes(DwarfCompileUnit &U, DIE &D) const {
 // Create new DwarfCompileUnit for the given metadata node with tag
 // DW_TAG_compile_unit.
 DwarfCompileUnit &
-DwarfDebug::constructDwarfCompileUnit(const DICompileUnit *DIUnit) {
+DwarfDebug::getOrCreateDwarfCompileUnit(const DICompileUnit *DIUnit) {
+  if (auto *CU = CUMap.lookup(DIUnit))
+    return *CU;
   StringRef FN = DIUnit->getFilename();
   CompilationDir = DIUnit->getDirectory();
 
@@ -540,7 +542,12 @@ void DwarfDebug::beginModule() {
   }
 
   for (DICompileUnit *CUNode : M->debug_compile_units()) {
-    DwarfCompileUnit &CU = constructDwarfCompileUnit(CUNode);
+    if (CUNode->getEnumTypes().empty() && CUNode->getRetainedTypes().empty() &&
+        CUNode->getGlobalVariables().empty() &&
+        CUNode->getImportedEntities().empty() && CUNode->getMacros().empty())
+      continue;
+
+    DwarfCompileUnit &CU = getOrCreateDwarfCompileUnit(CUNode);
     for (auto *IE : CUNode->getImportedEntities())
       CU.addImportedEntity(IE);
 
@@ -587,11 +594,12 @@ void DwarfDebug::finishVariableDefinitions() {
 }
 
 void DwarfDebug::finishSubprogramDefinitions() {
-  for (const DISubprogram *SP : ProcessedSPNodes)
-    if (SP->getUnit()->getEmissionKind() != DICompileUnit::NoDebug)
-      forBothCUs(*CUMap.lookup(SP->getUnit()), [&](DwarfCompileUnit &CU) {
-        CU.finishSubprogramDefinition(SP);
-      });
+  for (const DISubprogram *SP : ProcessedSPNodes) {
+    assert(SP->getUnit()->getEmissionKind() != DICompileUnit::NoDebug);
+    forBothCUs(
+        getOrCreateDwarfCompileUnit(SP->getUnit()),
+        [&](DwarfCompileUnit &CU) { CU.finishSubprogramDefinition(SP); });
+  }
 }
 
 void DwarfDebug::finalizeModuleInfo() {
@@ -1136,12 +1144,10 @@ void DwarfDebug::beginFunctionImpl(const MachineFunction *MF) {
 
   auto *SP = MF->getFunction()->getSubprogram();
   assert(LScopes.empty() || SP == LScopes.getCurrentFunctionScope()->getScopeNode());
-  DwarfCompileUnit *TheCU = CUMap.lookup(SP->getUnit());
-  if (!TheCU) {
-    assert(SP->getUnit()->getEmissionKind() == DICompileUnit::NoDebug &&
-           "DICompileUnit missing from llvm.dbg.cu?");
+  if (SP->getUnit()->getEmissionKind() == DICompileUnit::NoDebug)
     return;
-  }
+
+  DwarfCompileUnit &CU = getOrCreateDwarfCompileUnit(SP->getUnit());
 
   // Set DwarfDwarfCompileUnitID in MCContext to the Compile Unit this function
   // belongs to so that we add to the correct per-cu line table in the
@@ -1150,7 +1156,7 @@ void DwarfDebug::beginFunctionImpl(const MachineFunction *MF) {
     // Use a single line table if we are generating assembly.
     Asm->OutStreamer->getContext().setDwarfCompileUnitID(0);
   else
-    Asm->OutStreamer->getContext().setDwarfCompileUnitID(TheCU->getUniqueID());
+    Asm->OutStreamer->getContext().setDwarfCompileUnitID(CU.getUniqueID());
 
   // Record beginning of function.
   PrologEndLoc = findPrologueEndLoc(MF);
@@ -1546,6 +1552,9 @@ void DwarfDebug::emitDebugLocEntryLocation(const DebugLocStream::Entry &Entry) {
 
 // Emit locations into the debug loc section.
 void DwarfDebug::emitDebugLoc() {
+  if (DebugLocs.getLists().empty())
+    return;
+
   // Start the dwarf loc section.
   Asm->OutStreamer->SwitchSection(
       Asm->getObjFileLowering().getDwarfLocSection());
@@ -1757,6 +1766,9 @@ void DwarfDebug::emitDebugARanges() {
 
 /// Emit address ranges into a debug ranges section.
 void DwarfDebug::emitDebugRanges() {
+  if (CUMap.empty())
+    return;
+
   // Start the dwarf ranges section.
   Asm->OutStreamer->SwitchSection(
       Asm->getObjFileLowering().getDwarfRangesSection());
@@ -1836,6 +1848,9 @@ void DwarfDebug::emitMacroFile(DIMacroFile &F, DwarfCompileUnit &U) {
 
 /// Emit macros into a debug macinfo section.
 void DwarfDebug::emitDebugMacinfo() {
+  if (CUMap.empty())
+    return;
+
   // Start the dwarf macinfo section.
   Asm->OutStreamer->SwitchSection(
       Asm->getObjFileLowering().getDwarfMacinfoSection());
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
index 97b96dd6e04..ebfba4cfc27 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -416,7 +416,7 @@ class DwarfDebug : public DebugHandlerBase {
 
   /// Create new DwarfCompileUnit for the given metadata node with tag
   /// DW_TAG_compile_unit.
-  DwarfCompileUnit &constructDwarfCompileUnit(const DICompileUnit *DIUnit);
+  DwarfCompileUnit &getOrCreateDwarfCompileUnit(const DICompileUnit *DIUnit);
 
   /// Construct imported_module or imported_declaration DIE.
   void constructAndAddImportedEntityDIE(DwarfCompileUnit &TheCU,