[dsymutil] Add support for generating DWARF5 accelerator tables.

This patch add support for emitting DWARF5 accelerator tables
(.debug_names) from dsymutil. Just as with the Apple style accelerator
tables, it's possible to update existing dSYMs. This patch includes a
test that show how you can convert back and forth between the two types.

If no kind of table is specified, dsymutil will default to generating
Apple-style accelerator tables whenever it finds those in its input. The
same is true when there are no accelerator tables at all. Finally, in
the remaining case, where there's at least one DWARF v5 table and no
Apple ones, the output will contains a DWARF accelerator tables
(.debug_names).

Differential revision: https://reviews.llvm.org/D49137

llvm-svn: 337980

1 files changed, 85 insertions, 11 deletions

diff --git a/llvm/tools/dsymutil/DwarfLinker.cpp b/llvm/tools/dsymutil/DwarfLinker.cpp
index f21873f2fb5..e685a59277b 100644
--- a/llvm/tools/dsymutil/DwarfLinker.cpp
+++ b/llvm/tools/dsymutil/DwarfLinker.cpp
@@ -321,6 +321,7 @@ void DwarfLinker::startDebugObject(LinkContext &Context) {
 
 void DwarfLinker::endDebugObject(LinkContext &Context) {
   Context.Clear();
+
   for (auto I = DIEBlocks.begin(), E = DIEBlocks.end(); I != E; ++I)
     (*I)->~DIEBlock();
   for (auto I = DIELocs.begin(), E = DIELocs.end(); I != E; ++I)
@@ -1746,6 +1747,20 @@ void DwarfLinker::patchLineTableForUnit(CompileUnit &Unit,
 }
 
 void DwarfLinker::emitAcceleratorEntriesForUnit(CompileUnit &Unit) {
+  switch (Options.TheAccelTableKind) {
+  case AccelTableKind::Apple:
+    emitAppleAcceleratorEntriesForUnit(Unit);
+    break;
+  case AccelTableKind::Dwarf:
+    emitDwarfAcceleratorEntriesForUnit(Unit);
+    break;
+  case AccelTableKind::Default:
+    llvm_unreachable("The default must be updated to a concrete value.");
+    break;
+  }
+}
+
+void DwarfLinker::emitAppleAcceleratorEntriesForUnit(CompileUnit &Unit) {
   // Add namespaces.
   for (const auto &Namespace : Unit.getNamespaces())
     AppleNamespaces.addName(Namespace.Name,
@@ -1774,6 +1789,18 @@ void DwarfLinker::emitAcceleratorEntriesForUnit(CompileUnit &Unit) {
     AppleObjc.addName(ObjC.Name, ObjC.Die->getOffset() + Unit.getStartOffset());
 }
 
+void DwarfLinker::emitDwarfAcceleratorEntriesForUnit(CompileUnit &Unit) {
+  for (const auto &Namespace : Unit.getNamespaces())
+    DebugNames.addName(Namespace.Name, Namespace.Die->getOffset(),
+                       Namespace.Die->getTag(), Unit.getUniqueID());
+  for (const auto &Pubname : Unit.getPubnames())
+    DebugNames.addName(Pubname.Name, Pubname.Die->getOffset(),
+                       Pubname.Die->getTag(), Unit.getUniqueID());
+  for (const auto &Pubtype : Unit.getPubtypes())
+    DebugNames.addName(Pubtype.Name, Pubtype.Die->getOffset(),
+                       Pubtype.Die->getTag(), Unit.getUniqueID());
+}
+
 /// Read the frame info stored in the object, and emit the
 /// patched frame descriptions for the linked binary.
 ///
@@ -2063,9 +2090,9 @@ Error DwarfLinker::loadClangModule(StringRef Filename, StringRef ModulePath,
   // Setup access to the debug info.
   auto DwarfContext = DWARFContext::create(*ErrOrObj);
   RelocationManager RelocMgr(*this);
-  for (const auto &CU : DwarfContext->compile_units()) {
-    maybeUpdateMaxDwarfVersion(CU->getVersion());
 
+  for (const auto &CU : DwarfContext->compile_units()) {
+    updateDwarfVersion(CU->getVersion());
     // Recursively get all modules imported by this one.
     auto CUDie = CU->getUnitDIE(false);
     if (!CUDie)
@@ -2172,6 +2199,26 @@ void DwarfLinker::DIECloner::cloneAllCompileUnits(
   }
 }
 
+void DwarfLinker::updateAccelKind(DWARFContext &Dwarf) {
+  if (Options.TheAccelTableKind != AccelTableKind::Default)
+    return;
+
+  auto &DwarfObj = Dwarf.getDWARFObj();
+
+  if (!AtLeastOneDwarfAccelTable &&
+      (!DwarfObj.getAppleNamesSection().Data.empty() ||
+       !DwarfObj.getAppleTypesSection().Data.empty() ||
+       !DwarfObj.getAppleNamespacesSection().Data.empty() ||
+       !DwarfObj.getAppleObjCSection().Data.empty())) {
+    AtLeastOneAppleAccelTable = true;
+  }
+
+  if (!AtLeastOneDwarfAccelTable &&
+      !DwarfObj.getDebugNamesSection().Data.empty()) {
+    AtLeastOneDwarfAccelTable = true;
+  }
+}
+
 bool DwarfLinker::emitPaperTrailWarnings(const DebugMapObject &DMO,
                                          const DebugMap &Map,
                                          OffsetsStringPool &StringPool) {
@@ -2245,8 +2292,12 @@ bool DwarfLinker::link(const DebugMap &Map) {
   unsigned NumObjects = Map.getNumberOfObjects();
   std::vector<LinkContext> ObjectContexts;
   ObjectContexts.reserve(NumObjects);
-  for (const auto &Obj : Map.objects())
+  for (const auto &Obj : Map.objects()) {
     ObjectContexts.emplace_back(Map, *this, *Obj.get());
+    LinkContext &LC = ObjectContexts.back();
+    if (LC.ObjectFile)
+      updateAccelKind(*LC.DwarfContext);
+  }
 
   // This Dwarf string pool which is only used for uniquing. This one should
   // never be used for offsets as its not thread-safe or predictable.
@@ -2260,6 +2311,19 @@ bool DwarfLinker::link(const DebugMap &Map) {
   // ODR Contexts for the link.
   DeclContextTree ODRContexts;
 
+  // If we haven't decided on an accelerator table kind yet, we base ourselves
+  // on the DWARF we have seen so far. At this point we haven't pulled in debug
+  // information from modules yet, so it is technically possible that they
+  // would affect the decision. However, as they're built with the same
+  // compiler and flags, it is safe to assume that they will follow the
+  // decision made here.
+  if (Options.TheAccelTableKind == AccelTableKind::Default) {
+    if (AtLeastOneDwarfAccelTable && !AtLeastOneAppleAccelTable)
+      Options.TheAccelTableKind = AccelTableKind::Dwarf;
+    else
+      Options.TheAccelTableKind = AccelTableKind::Apple;
+  }
+
   for (LinkContext &LinkContext : ObjectContexts) {
     if (Options.Verbose)
       outs() << "DEBUG MAP OBJECT: " << LinkContext.DMO.getObjectFilename()
@@ -2325,7 +2389,9 @@ bool DwarfLinker::link(const DebugMap &Map) {
     // In a first phase, just read in the debug info and load all clang modules.
     LinkContext.CompileUnits.reserve(
         LinkContext.DwarfContext->getNumCompileUnits());
+
     for (const auto &CU : LinkContext.DwarfContext->compile_units()) {
+      updateDwarfVersion(CU->getVersion());
       auto CUDie = CU->getUnitDIE(false);
       if (Options.Verbose) {
         outs() << "Input compilation unit:";
@@ -2341,13 +2407,11 @@ bool DwarfLinker::link(const DebugMap &Map) {
                                    UniquingStringPool, ODRContexts, UnitID)) {
         LinkContext.CompileUnits.push_back(llvm::make_unique<CompileUnit>(
             *CU, UnitID++, !Options.NoODR && !Options.Update, ""));
-        maybeUpdateMaxDwarfVersion(CU->getVersion());
       }
     }
   }
 
-  // If we haven't seen any CUs, pick an arbitrary valid Dwarf version anyway,
-  // to be able to emit papertrail warnings.
+  // If we haven't seen any CUs, pick an arbitrary valid Dwarf version anyway.
   if (MaxDwarfVersion == 0)
     MaxDwarfVersion = 3;
 
@@ -2444,10 +2508,20 @@ bool DwarfLinker::link(const DebugMap &Map) {
     if (!Options.NoOutput) {
       Streamer->emitAbbrevs(Abbreviations, MaxDwarfVersion);
       Streamer->emitStrings(OffsetsStringPool);
-      Streamer->emitAppleNames(AppleNames);
-      Streamer->emitAppleNamespaces(AppleNamespaces);
-      Streamer->emitAppleTypes(AppleTypes);
-      Streamer->emitAppleObjc(AppleObjc);
+      switch (Options.TheAccelTableKind) {
+      case AccelTableKind::Apple:
+        Streamer->emitAppleNames(AppleNames);
+        Streamer->emitAppleNamespaces(AppleNamespaces);
+        Streamer->emitAppleTypes(AppleTypes);
+        Streamer->emitAppleObjc(AppleObjc);
+        break;
+      case AccelTableKind::Dwarf:
+        Streamer->emitDebugNames(DebugNames);
+        break;
+      case AccelTableKind::Default:
+        llvm_unreachable("Default should have already been resolved.");
+        break;
+      }
     }
   };
 
@@ -2465,7 +2539,7 @@ bool DwarfLinker::link(const DebugMap &Map) {
   }
 
   return Options.NoOutput ? true : Streamer->finish(Map);
-}
+} // namespace dsymutil
 
 bool linkDwarf(raw_fd_ostream &OutFile, BinaryHolder &BinHolder,
                const DebugMap &DM, const LinkOptions &Options) {