[DebugInfo] Fix emission of empty debug_names for Apple

[fdeazeve]

Summary

D118754 added a new DICompileUnit::DebugNameTableKind for "Apple", so that,
under DWARF 5, the following combination is used inside DwarfDebug.cpp:

(lldb) p getAccelTableKind()
(llvm::AccelTableKind) $6 = Dwarf
(lldb) p CU.getNameTableKind()
(llvm::DICompileUnit::DebugNameTableKind) $7 = Apple

This creates a problem in the if statements changed, whereby "for non Apple
AccelTableKind" we emit empty tables for any DebugNameTableKind that is not
"Default". We should consider the newly added kind here too.

Note that our existing test could have caught this, if only it had checked the
_contents_ of the table, instead of only checking for the existence of the
section.

[fdeazeve]

Trying to add context to the review

[JDevlieghere]

LGTM. Thanks!

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

 static StringRef getObjCMethodName(StringRef In) {
   return In.slice(In.find(' ') + 1, In.find(']'));
 }
 
 // Add the various names to the Dwarf accelerator table names.
 void DwarfDebug::addSubprogramNames(const DICompileUnit &CU,
                                     const DISubprogram *SP, DIE &Die) {
   if (getAccelTableKind() != AccelTableKind::Apple &&
+      CU.getNameTableKind() != DICompileUnit::DebugNameTableKind::Apple &&
       CU.getNameTableKind() == DICompileUnit::DebugNameTableKind::None)
     return;
 
   if (!SP->isDefinition())
     return;
 
   if (SP->getName() != "")
     addAccelName(CU, SP->getName(), Die);

 template <typename DataT>
 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::Apple &&
       CU.getNameTableKind() != DICompileUnit::DebugNameTableKind::Default)
     return;
 
   DwarfFile &Holder = useSplitDwarf() ? SkeletonHolder : InfoHolder;
   DwarfStringPoolEntryRef Ref = Holder.getStringPool().getEntry(*Asm, Name);
 
   switch (getAccelTableKind()) {
   case AccelTableKind::Apple:

llvm/test/DebugInfo/accel-tables-apple.ll

 ; Verify the emission of accelerator tables for nameTableKind: Apple
 ; REQUIRES: x86-registered-target
 
-; RUN: llc -mtriple=x86_64-apple-darwin12 -filetype=obj < %S/Inputs/name-table-kind-apple-5.ll \
-; RUN:   | llvm-readobj --sections - | FileCheck --check-prefix=DEBUG_NAMES %s
+; RUN: llc -mtriple=x86_64-apple-darwin12 -filetype=obj -o %t.d5.o < %S/Inputs/name-table-kind-apple-5.ll
+; RUN:   llvm-readobj --sections %t.d5.o | FileCheck --check-prefix=DEBUG_NAMES %s
+; RUN:   llvm-dwarfdump --debug-names %t.d5.o | FileCheck --check-prefix=COUNT_DEBUG_NAMES %s
 
 ; RUN: llc -mtriple=x86_64-apple-darwin12 -filetype=obj < %S/Inputs/name-table-kind-apple-4.ll \
 ; RUN:   | llvm-readobj --sections - | FileCheck --check-prefix=APPLE %s
 
 ; APPLE-NOT: debug_names
 ; APPLE-NOT: debug{{.*}}pub
 ; APPLE: apple_names
 ; APPLE-NOT: debug_names
 ; APPLE-NOT: debug{{.*}}pub
 
 ; DEBUG_NAMES-NOT: apple_names
 ; DEBUG_NAMES-NOT: pubnames
 ; DEBUG_NAMES: debug_names
 ; DEBUG_NAMES-NOT: apple_names
 ; DEBUG_NAMES-NOT: pubnames
+
+; COUNT_DEBUG_NAMES: Name count: 4