DebugInfo: Add metadata support for disabling DWARF pub sections

In cases where the debugger load time is a worthwhile tradeoff (or less
costly - such as loading from a DWP instead of a variety of DWOs
(possibly over a high-latency/distributed filesystem)) against object
file size, it can be reasonable to disable pubnames and corresponding
gdb-index creation in the linker.

A backend-flag version of this was implemented for NVPTX in
D44385/r327994 - which was fine for NVPTX which wouldn't mix-and-match
CUs. Now that it's going to be a user-facing option (likely powered by
"-gno-pubnames", the same as GCC) it should be encoded in the
DICompileUnit so it can vary per-CU.

After this, likely the NVPTX support should be migrated to the metadata
& the previous flag implementation should be removed.

Reviewers: aprantl

Differential Revision: https://reviews.llvm.org/D50213

llvm-svn: 339939

1 files changed, 31 insertions, 18 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 6ee1de0dba3..435190669a4 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -421,30 +421,35 @@ static StringRef getObjCMethodName(StringRef In) {
 }
 
 // Add the various names to the Dwarf accelerator table names.
-void DwarfDebug::addSubprogramNames(const DISubprogram *SP, DIE &Die) {
+void DwarfDebug::addSubprogramNames(const DICompileUnit &CU,
+                                    const DISubprogram *SP, DIE &Die) {
+  if (getAccelTableKind() != AccelTableKind::Apple &&
+      CU.getNameTableKind() == DICompileUnit::DebugNameTableKind::None)
+    return;
+
   if (!SP->isDefinition())
     return;
 
   if (SP->getName() != "")
-    addAccelName(SP->getName(), Die);
+    addAccelName(CU, SP->getName(), Die);
 
   // If the linkage name is different than the name, go ahead and output that as
   // well into the name table. Only do that if we are going to actually emit
   // that name.
   if (SP->getLinkageName() != "" && SP->getName() != SP->getLinkageName() &&
       (useAllLinkageNames() || InfoHolder.getAbstractSPDies().lookup(SP)))
-    addAccelName(SP->getLinkageName(), Die);
+    addAccelName(CU, SP->getLinkageName(), Die);
 
   // If this is an Objective-C selector name add it to the ObjC accelerator
   // too.
   if (isObjCClass(SP->getName())) {
     StringRef Class, Category;
     getObjCClassCategory(SP->getName(), Class, Category);
-    addAccelObjC(Class, Die);
+    addAccelObjC(CU, Class, Die);
     if (Category != "")
-      addAccelObjC(Category, Die);
+      addAccelObjC(CU, Category, Die);
     // Also add the base method name to the name table.
-    addAccelName(getObjCMethodName(SP->getName()), Die);
+    addAccelName(CU, getObjCMethodName(SP->getName()), Die);
   }
 }
 
@@ -1537,8 +1542,6 @@ void DwarfDebug::emitAccelDebugNames() {
   if (getUnits().empty())
     return;
 
-  Asm->OutStreamer->SwitchSection(
-      Asm->getObjFileLowering().getDwarfDebugNamesSection());
   emitDWARF5AccelTable(Asm, AccelDebugNames, *this, getUnits());
 }
 
@@ -1643,7 +1646,8 @@ void DwarfDebug::emitDebugPubSections() {
     if (!TheU->hasDwarfPubSections())
       continue;
 
-    bool GnuStyle = TheU->getCUNode()->getGnuPubnames();
+    bool GnuStyle = TheU->getCUNode()->getNameTableKind() ==
+                    DICompileUnit::DebugNameTableKind::GNU;
 
     Asm->OutStreamer->SwitchSection(
         GnuStyle ? Asm->getObjFileLowering().getDwarfGnuPubNamesSection()
@@ -2431,11 +2435,16 @@ void DwarfDebug::addDwarfTypeUnitType(DwarfCompileUnit &CU,
 // AccelTableKind::Apple, we use the table we got as an argument). If
 // accelerator tables are disabled, this function does nothing.
 template <typename DataT>
-void DwarfDebug::addAccelNameImpl(AccelTable<DataT> &AppleAccel, StringRef Name,
+void DwarfDebug::addAccelNameImpl(const DICompileUnit &CU,
+                                  AccelTable<DataT> &AppleAccel, StringRef Name,
                                   const DIE &Die) {
   if (getAccelTableKind() == AccelTableKind::None)
     return;
 
+  if (getAccelTableKind() != AccelTableKind::Apple &&
+      CU.getNameTableKind() == DICompileUnit::DebugNameTableKind::None)
+    return;
+
   DwarfFile &Holder = useSplitDwarf() ? SkeletonHolder : InfoHolder;
   DwarfStringPoolEntryRef Ref = Holder.getStringPool().getEntry(*Asm, Name);
 
@@ -2453,22 +2462,26 @@ void DwarfDebug::addAccelNameImpl(AccelTable<DataT> &AppleAccel, StringRef Name,
   }
 }
 
-void DwarfDebug::addAccelName(StringRef Name, const DIE &Die) {
-  addAccelNameImpl(AccelNames, Name, Die);
+void DwarfDebug::addAccelName(const DICompileUnit &CU, StringRef Name,
+                              const DIE &Die) {
+  addAccelNameImpl(CU, AccelNames, Name, Die);
 }
 
-void DwarfDebug::addAccelObjC(StringRef Name, const DIE &Die) {
+void DwarfDebug::addAccelObjC(const DICompileUnit &CU, StringRef Name,
+                              const DIE &Die) {
   // ObjC names go only into the Apple accelerator tables.
   if (getAccelTableKind() == AccelTableKind::Apple)
-    addAccelNameImpl(AccelObjC, Name, Die);
+    addAccelNameImpl(CU, AccelObjC, Name, Die);
 }
 
-void DwarfDebug::addAccelNamespace(StringRef Name, const DIE &Die) {
-  addAccelNameImpl(AccelNamespace, Name, Die);
+void DwarfDebug::addAccelNamespace(const DICompileUnit &CU, StringRef Name,
+                                   const DIE &Die) {
+  addAccelNameImpl(CU, AccelNamespace, Name, Die);
 }
 
-void DwarfDebug::addAccelType(StringRef Name, const DIE &Die, char Flags) {
-  addAccelNameImpl(AccelTypes, Name, Die);
+void DwarfDebug::addAccelType(const DICompileUnit &CU, StringRef Name,
+                              const DIE &Die, char Flags) {
+  addAccelNameImpl(CU, AccelTypes, Name, Die);
 }
 
 uint16_t DwarfDebug::getDwarfVersion() const {