Add initial support for handling gnu style pubnames accepted by some

versions of gold. This support is designed to allow gold to produce
gdb_index sections similar to the accelerator tables and consumable
by gdb.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190649 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 265 insertions, 9 deletions

diff --git a/include/llvm/Support/Dwarf.h b/include/llvm/Support/Dwarf.h
index a31c3f1..a1ed1d1 100644
--- a/include/llvm/Support/Dwarf.h
+++ b/include/llvm/Support/Dwarf.h
@@ -791,6 +791,17 @@ const char *AtomTypeString(unsigned Atom);
 
 // Constants for the GNU pubnames/pubtypes extensions supporting gdb index.
 enum GDBIndex {
+  // The full index looks like this for each symbol:
+  //
+  // 0-23   CU index
+  // 24-27  reserved
+  // 28-30  symbol kind
+  // 31     0 == global, 1 == static
+  //
+  // where each entry refers to the CU and some attributes about the symbol.
+
+  // Attributes kinds for the index.
+
   // Special value to indicate no attributes are present.
   GDB_INDEX_SYMBOL_KIND_NONE = 0,
   GDB_INDEX_SYMBOL_KIND_TYPE = 1,
@@ -800,7 +811,17 @@ enum GDBIndex {
   // 3 unused bits.
   GDB_INDEX_SYMBOL_KIND_UNUSED5 = 5,
   GDB_INDEX_SYMBOL_KIND_UNUSED6 = 6,
-  GDB_INDEX_SYMBOL_KIND_UNUSED7 = 7
+  GDB_INDEX_SYMBOL_KIND_UNUSED7 = 7,
+
+  // Index values are defined via the set of CUs that define the
+  // symbol. For the pubnames/pubtypes extensions we need the
+  // various shifts and masks.
+  GDB_INDEX_SYMBOL_STATIC_SHIFT = 31,
+  GDB_INDEX_SYMBOL_STATIC_MASK = 1,
+  GDB_INDEX_SYMBOL_KIND_SHIFT = 28,
+  GDB_INDEX_SYMBOL_KIND_MASK = 7,
+  GDB_INDEX_CU_BITSIZE = 24,
+  GDB_INDEX_CU_MASK = ((1 << GDB_INDEX_CU_BITSIZE) - 1)
 };
 
 /// GDBIndexTypeString - Return the string for the specified index type.
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index f155647..4f62ab9 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -68,6 +68,11 @@ GenerateCUHash("generate-cu-hash", cl::Hidden,
                cl::desc("Add the CU hash as the dwo_id."),
                cl::init(false));
 
+static cl::opt<bool>
+GenerateGnuPubSections("generate-gnu-dwarf-pub-sections", cl::Hidden,
+                       cl::desc("Generate GNU-style pubnames and pubtypes"),
+                       cl::init(false));
+
 namespace {
 enum DefaultOnOff {
   Default,
@@ -768,6 +773,12 @@ CompileUnit *DwarfDebug::constructCompileUnit(const MDNode *N) {
   // skeleton CU and so we don't need to duplicate it here.
   if (!useSplitDwarf() && !CompilationDir.empty())
     NewCU->addString(Die, dwarf::DW_AT_comp_dir, CompilationDir);
+
+  // Flag 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.
+  if (!useSplitDwarf() && GenerateGnuPubSections)
+    NewCU->addFlag(Die, dwarf::DW_AT_GNU_pubnames);
+
   if (DIUnit.isOptimized())
     NewCU->addFlag(Die, dwarf::DW_AT_APPLE_optimized);
 
@@ -1149,8 +1160,8 @@ void DwarfDebug::endModule() {
 
   // Emit the pubnames and pubtypes sections if requested.
   if (HasDwarfPubSections) {
-    emitDebugPubNames();
-    emitDebugPubTypes();
+    emitDebugPubNames(GenerateGnuPubSections ? true : false);
+    emitDebugPubTypes(GenerateGnuPubSections ? true : false);
   }
 
   // Finally emit string information into a string table.
@@ -1933,7 +1944,11 @@ void DwarfDebug::emitSectionLabels() {
   if (HasDwarfPubSections) {
     emitSectionSym(Asm, TLOF.getDwarfPubNamesSection());
     emitSectionSym(Asm, TLOF.getDwarfPubTypesSection());
+  } else if (GenerateGnuPubSections) {
+    emitSectionSym(Asm, TLOF.getDwarfGnuPubNamesSection());
+    emitSectionSym(Asm, TLOF.getDwarfGnuPubTypesSection());
   }
+
   DwarfStrSectionSym =
     emitSectionSym(Asm, TLOF.getDwarfStrSection(), "info_string");
   if (useSplitDwarf()) {
@@ -2292,11 +2307,83 @@ void DwarfDebug::emitAccelTypes() {
   AT.Emit(Asm, SectionBegin, &InfoHolder);
 }
 
+// Public name handling.
+// The format for the various pubnames:
+//
+// dwarf pubnames - offset/name pairs where the offset is the offset into the CU
+// for the DIE that is named.
+//
+// gnu pubnames - offset/index value/name tuples where the offset is the offset
+// into the CU and the index value is computed according to the type of value
+// for the DIE that is named.
+//
+// For type units the offset is the offset of the skeleton DIE. For split dwarf
+// it's the offset within the debug_info/debug_types dwo section, however, the
+// reference in the pubname header doesn't change.
+
+/// computeIndexValue - Compute the gdb index value for the DIE and CU.
+static uint8_t computeIndexValue(CompileUnit *CU, DIE *Die) {
+#define UPDATE_VALUE(CURRENT, VALUE)                                           \
+  {                                                                            \
+    (CURRENT) |= (((VALUE) & dwarf::GDB_INDEX_SYMBOL_KIND_MASK)                \
+                  << dwarf::GDB_INDEX_SYMBOL_KIND_SHIFT);                      \
+  }
+
+#define UPDATE_STATIC(CURRENT, IS_STATIC)                                      \
+  {                                                                            \
+    (CURRENT) |= (((IS_STATIC) & dwarf::GDB_INDEX_SYMBOL_STATIC_MASK)          \
+                  << dwarf::GDB_INDEX_SYMBOL_STATIC_SHIFT);                    \
+  }
+
+  // Compute the Attributes for the Die.
+  uint32_t Value = dwarf::GDB_INDEX_SYMBOL_KIND_NONE;
+  bool External =
+      Die->findAttribute(dwarf::DW_AT_external) != NULL ? true : false;
+
+  switch (Die->getTag()) {
+  case dwarf::DW_TAG_class_type:
+  case dwarf::DW_TAG_structure_type:
+  case dwarf::DW_TAG_union_type:
+  case dwarf::DW_TAG_enumeration_type:
+  case dwarf::DW_TAG_typedef:
+  case dwarf::DW_TAG_base_type:
+  case dwarf::DW_TAG_subrange_type:
+    UPDATE_VALUE(Value, dwarf::GDB_INDEX_SYMBOL_KIND_TYPE);
+    UPDATE_STATIC(Value, 1);
+    break;
+  case dwarf::DW_TAG_namespace:
+    UPDATE_VALUE(Value, dwarf::GDB_INDEX_SYMBOL_KIND_TYPE);
+    break;
+  case dwarf::DW_TAG_subprogram:
+    UPDATE_VALUE(Value, dwarf::GDB_INDEX_SYMBOL_KIND_FUNCTION);
+    UPDATE_STATIC(Value, !External);
+    break;
+  case dwarf::DW_TAG_constant:
+  case dwarf::DW_TAG_variable:
+    UPDATE_VALUE(Value, dwarf::GDB_INDEX_SYMBOL_KIND_VARIABLE);
+    UPDATE_STATIC(Value, !External);
+    break;
+  case dwarf::DW_TAG_enumerator:
+    UPDATE_VALUE(Value, dwarf::GDB_INDEX_SYMBOL_KIND_VARIABLE);
+    UPDATE_STATIC(Value, 1);
+    break;
+  default:
+    break;
+  }
+  // We don't need to add the CU into the bitmask for two reasons:
+  // a) the pubnames/pubtypes sections are per-cpu, and
+  // b) the linker wouldn't understand it anyhow.
+  // so go ahead and make it 1 byte by shifting it down.
+  return Value >> dwarf::GDB_INDEX_CU_BITSIZE;
+}
+
 /// emitDebugPubNames - Emit visible names into a debug pubnames section.
 ///
-void DwarfDebug::emitDebugPubNames() {
+void DwarfDebug::emitDebugPubNames(bool GnuStyle) {
   const MCSection *ISec = Asm->getObjFileLowering().getDwarfInfoSection();
-  const MCSection *PSec = Asm->getObjFileLowering().getDwarfPubNamesSection();
+  const MCSection *PSec =
+      GnuStyle ? Asm->getObjFileLowering().getDwarfGnuPubNamesSection()
+               : Asm->getObjFileLowering().getDwarfPubNamesSection();
 
   typedef DenseMap<const MDNode*, CompileUnit*> CUMapType;
   for (CUMapType::iterator I = CUMap.begin(), E = CUMap.end(); I != E; ++I) {
@@ -2309,6 +2396,7 @@ void DwarfDebug::emitDebugPubNames() {
     // Start the dwarf pubnames section.
     Asm->OutStreamer.SwitchSection(PSec);
 
+    // Emit the header.
     Asm->OutStreamer.AddComment("Length of Public Names Info");
     Asm->EmitLabelDifference(Asm->GetTempSymbol("pubnames_end", ID),
                              Asm->GetTempSymbol("pubnames_begin", ID), 4);
@@ -2327,15 +2415,21 @@ void DwarfDebug::emitDebugPubNames() {
                              Asm->GetTempSymbol(ISec->getLabelBeginName(), ID),
                              4);
 
+    // Emit the pubnames for this compilation unit.
     const StringMap<DIE*> &Globals = TheCU->getGlobalNames();
     for (StringMap<DIE*>::const_iterator
            GI = Globals.begin(), GE = Globals.end(); GI != GE; ++GI) {
       const char *Name = GI->getKeyData();
-      const DIE *Entity = GI->second;
+      DIE *Entity = GI->second;
 
       Asm->OutStreamer.AddComment("DIE offset");
       Asm->EmitInt32(Entity->getOffset());
 
+      if (GnuStyle) {
+        Asm->OutStreamer.AddComment("Index value");
+        Asm->EmitInt8(computeIndexValue(TheCU, Entity));
+      }
+
       if (Asm->isVerbose())
         Asm->OutStreamer.AddComment("External Name");
       Asm->OutStreamer.EmitBytes(StringRef(Name, GI->getKeyLength()+1));
@@ -2347,7 +2441,7 @@ void DwarfDebug::emitDebugPubNames() {
   }
 }
 
-void DwarfDebug::emitDebugPubTypes() {
+void DwarfDebug::emitDebugPubTypes(bool GnuStyle) {
   const MCSection *ISec = Asm->getObjFileLowering().getDwarfInfoSection();
   const MCSection *PSec = Asm->getObjFileLowering().getDwarfPubTypesSection();
 
@@ -2390,6 +2484,11 @@ void DwarfDebug::emitDebugPubTypes() {
         Asm->OutStreamer.AddComment("DIE offset");
       Asm->EmitInt32(Entity->getOffset());
 
+      if (GnuStyle) {
+        Asm->OutStreamer.AddComment("Index value");
+        Asm->EmitInt8(computeIndexValue(TheCU, Entity));
+      }
+
       if (Asm->isVerbose())
         Asm->OutStreamer.AddComment("External Name");
 
@@ -2651,6 +2750,10 @@ CompileUnit *DwarfDebug::constructSkeletonCU(const CompileUnit *CU) {
   if (!CompilationDir.empty())
     NewCU->addLocalString(Die, dwarf::DW_AT_comp_dir, CompilationDir);
 
+  // Flag to let the linker know we have emitted new style pubnames.
+  if (GenerateGnuPubSections)
+    NewCU->addFlag(Die, dwarf::DW_AT_GNU_pubnames);
+
   SkeletonHolder.addUnit(NewCU);
   SkeletonCUs.push_back(NewCU);
 
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.h b/lib/CodeGen/AsmPrinter/DwarfDebug.h
index c702180..5a03e9f 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -533,10 +533,16 @@ private:
   void emitAccelTypes();
 
   /// \brief Emit visible names into a debug pubnames section.
-  void emitDebugPubNames();
+  /// \param GnuStyle determines whether or not we want to emit
+  /// additional information into the table ala newer gcc for gdb
+  /// index.
+  void emitDebugPubNames(bool GnuStyle = false);
 
   /// \brief Emit visible types into a debug pubtypes section.
-  void emitDebugPubTypes();
+  /// \param GnuStyle determines whether or not we want to emit
+  /// additional information into the table ala newer gcc for gdb
+  /// index.
+  void emitDebugPubTypes(bool GnuStyle = false);
 
   /// \brief Emit visible names into a debug str section.
   void emitDebugStr();
diff --git a/test/DebugInfo/X86/gnu-public-names.ll b/test/DebugInfo/X86/gnu-public-names.ll
new file mode 100644
index 0000000..68af3a1
--- /dev/null
+++ b/test/DebugInfo/X86/gnu-public-names.ll
@@ -0,0 +1,126 @@
+; RUN: llc -mtriple=x86_64-pc-linux-gnu -generate-gnu-dwarf-pub-sections -o - %s | FileCheck %s
+; ModuleID = 'dwarf-public-names.cpp'
+;
+; Generated from:
+;
+; struct C {
+;   void member_function();
+;   static int static_member_function();
+;   static int static_member_variable;
+; };
+;
+; int C::static_member_variable = 0;
+;
+; void C::member_function() {
+;   static_member_variable = 0;
+; }
+;
+; int C::static_member_function() {
+;   return static_member_variable;
+; }
+;
+; C global_variable;
+;
+; int global_function() {
+;   return -1;
+; }
+;
+; namespace ns {
+;   void global_namespace_function() {
+;     global_variable.member_function();
+;   }
+;   int global_namespace_variable = 1;
+; }
+
+
+; CHECK: .byte   32                      # Index value
+; CHECK-NEXT: .asciz   "global_namespace_variable" # External Name
+; CHECK: .byte   48                      # Index value
+; CHECK: .asciz   "global_namespace_function" # External Name
+; CHECK: .byte   176                     # Index value
+; CHECK: .asciz   "static_member_function" # External Name
+; CHECK: .byte   32                      # Index value
+; CHECK: .asciz   "global_variable"      # External Name
+; CHECK: .byte   48                      # Index value
+; CHECK: .asciz   "global_function"      # External Name
+; CHECK: .byte   176                     # Index value
+; CHECK: .asciz   "member_function"      # External Name
+
+%struct.C = type { i8 }
+
+@_ZN1C22static_member_variableE = global i32 0, align 4
+@global_variable = global %struct.C zeroinitializer, align 1
+@_ZN2ns25global_namespace_variableE = global i32 1, align 4
+
+define void @_ZN1C15member_functionEv(%struct.C* %this) nounwind uwtable align 2 {
+entry:
+  %this.addr = alloca %struct.C*, align 8
+  store %struct.C* %this, %struct.C** %this.addr, align 8
+  call void @llvm.dbg.declare(metadata !{%struct.C** %this.addr}, metadata !28), !dbg !30
+  %this1 = load %struct.C** %this.addr
+  store i32 0, i32* @_ZN1C22static_member_variableE, align 4, !dbg !31
+  ret void, !dbg !32
+}
+
+declare void @llvm.dbg.declare(metadata, metadata) nounwind readnone
+
+define i32 @_ZN1C22static_member_functionEv() nounwind uwtable align 2 {
+entry:
+  %0 = load i32* @_ZN1C22static_member_variableE, align 4, !dbg !33
+  ret i32 %0, !dbg !33
+}
+
+define i32 @_Z15global_functionv() nounwind uwtable {
+entry:
+  ret i32 -1, !dbg !34
+}
+
+define void @_ZN2ns25global_namespace_functionEv() nounwind uwtable {
+entry:
+  call void @_ZN1C15member_functionEv(%struct.C* @global_variable), !dbg !35
+  ret void, !dbg !36
+}
+
+attributes #0 = { nounwind uwtable }
+attributes #1 = { nounwind readnone }
+
+!llvm.dbg.cu = !{!0}
+
+!0 = metadata !{i32 786449, metadata !37, i32 4, metadata !"clang version 3.3 (http://llvm.org/git/clang.git a09cd8103a6a719cb2628cdf0c91682250a17bd2) (http://llvm.org/git/llvm.git 47d03cec0afca0c01ae42b82916d1d731716cd20)", i1 false, metadata !"", i32 0, metadata !1, metadata !1, metadata !2, metadata !24,  metadata !24, metadata !""} ; [ DW_TAG_compile_unit ] [/usr2/kparzysz/s.hex/t/dwarf-public-names.cpp] [DW_LANG_C_plus_plus]
+!1 = metadata !{i32 0}
+!2 = metadata !{metadata !3, metadata !18, metadata !19, metadata !20}
+!3 = metadata !{i32 786478, metadata !4, null, metadata !"member_function", metadata !"member_function", metadata !"_ZN1C15member_functionEv", i32 9, metadata !5, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 false, void (%struct.C*)* @_ZN1C15member_functionEv, null, metadata !12, metadata !1, i32 9} ; [ DW_TAG_subprogram ] [line 9] [def] [member_function]
+!4 = metadata !{i32 786473, metadata !37} ; [ DW_TAG_file_type ]
+!5 = metadata !{i32 786453, i32 0, null, i32 0, i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !6, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!6 = metadata !{null, metadata !7}
+!7 = metadata !{i32 786447, i32 0, null, i32 0, i32 0, i64 64, i64 64, i64 0, i32 1088, metadata !8} ; [ DW_TAG_pointer_type ] [line 0, size 64, align 64, offset 0] [artificial] [from C]
+!8 = metadata !{i32 786451, metadata !37, null, metadata !"C", i32 1, i64 8, i64 8, i32 0, i32 0, null, metadata !9, i32 0, null, null, null} ; [ DW_TAG_structure_type ] [C] [line 1, size 8, align 8, offset 0] [def] [from ]
+!9 = metadata !{metadata !10, metadata !12, metadata !14}
+!10 = metadata !{i32 786445, metadata !37, metadata !8, metadata !"static_member_variable", i32 4, i64 0, i64 0, i64 0, i32 4096, metadata !11, null} ; [ DW_TAG_member ] [static_member_variable] [line 4, size 0, align 0, offset 0] [static] [from int]
+!11 = metadata !{i32 786468, null, null, metadata !"int", i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ] [int] [line 0, size 32, align 32, offset 0, enc DW_ATE_signed]
+!12 = metadata !{i32 786478, metadata !4, metadata !8, metadata !"member_function", metadata !"member_function", metadata !"_ZN1C15member_functionEv", i32 2, metadata !5, i1 false, i1 false, i32 0, i32 0, null, i32 256, i1 false, null, null, i32 0, metadata !13, i32 2} ; [ DW_TAG_subprogram ] [line 2] [member_function]
+!13 = metadata !{i32 786468}                      ; [ DW_TAG_base_type ] [line 0, size 0, align 0, offset 0]
+!14 = metadata !{i32 786478, metadata !4, metadata !8, metadata !"static_member_function", metadata !"static_member_function", metadata !"_ZN1C22static_member_functionEv", i32 3, metadata !15, i1 false, i1 false, i32 0, i32 0, null, i32 256, i1 false, null, null, i32 0, metadata !17, i32 3} ; [ DW_TAG_subprogram ] [line 3] [static_member_function]
+!15 = metadata !{i32 786453, i32 0, null, i32 0, i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !16, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!16 = metadata !{metadata !11}
+!17 = metadata !{i32 786468}                      ; [ DW_TAG_base_type ] [line 0, size 0, align 0, offset 0]
+!18 = metadata !{i32 786478, metadata !4, null, metadata !"static_member_function", metadata !"static_member_function", metadata !"_ZN1C22static_member_functionEv", i32 13, metadata !15, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 false, i32 ()* @_ZN1C22static_member_functionEv, null, metadata !14, metadata !1, i32 13} ; [ DW_TAG_subprogram ] [line 13] [def] [static_member_function]
+!19 = metadata !{i32 786478, metadata !4, metadata !4, metadata !"global_function", metadata !"global_function", metadata !"_Z15global_functionv", i32 19, metadata !15, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 false, i32 ()* @_Z15global_functionv, null, null, metadata !1, i32 19} ; [ DW_TAG_subprogram ] [line 19] [def] [global_function]
+!20 = metadata !{i32 786478, metadata !4, metadata !21, metadata !"global_namespace_function", metadata !"global_namespace_function", metadata !"_ZN2ns25global_namespace_functionEv", i32 24, metadata !22, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 false, void ()* @_ZN2ns25global_namespace_functionEv, null, null, metadata !1, i32 24} ; [ DW_TAG_subprogram ] [line 24] [def] [global_namespace_function]
+!21 = metadata !{i32 786489, null, metadata !"ns", metadata !4, i32 23} ; [ DW_TAG_namespace ] [/usr2/kparzysz/s.hex/t/dwarf-public-names.cpp]
+!22 = metadata !{i32 786453, i32 0, null, i32 0, i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !23, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!23 = metadata !{null}
+!24 = metadata !{metadata !25, metadata !26, metadata !27}
+!25 = metadata !{i32 786484, i32 0, metadata !8, metadata !"static_member_variable", metadata !"static_member_variable", metadata !"_ZN1C22static_member_variableE", metadata !4, i32 7, metadata !11, i32 0, i32 1, i32* @_ZN1C22static_member_variableE, metadata !10} ; [ DW_TAG_variable ] [static_member_variable] [line 7] [def]
+!26 = metadata !{i32 786484, i32 0, null, metadata !"global_variable", metadata !"global_variable", metadata !"", metadata !4, i32 17, metadata !8, i32 0, i32 1, %struct.C* @global_variable, null} ; [ DW_TAG_variable ] [global_variable] [line 17] [def]
+!27 = metadata !{i32 786484, i32 0, metadata !21, metadata !"global_namespace_variable", metadata !"global_namespace_variable", metadata !"_ZN2ns25global_namespace_variableE", metadata !4, i32 27, metadata !11, i32 0, i32 1, i32* @_ZN2ns25global_namespace_variableE, null} ; [ DW_TAG_variable ] [global_namespace_variable] [line 27] [def]
+!28 = metadata !{i32 786689, metadata !3, metadata !"this", metadata !4, i32 16777225, metadata !29, i32 1088, i32 0} ; [ DW_TAG_arg_variable ] [this] [line 9]
+!29 = metadata !{i32 786447, null, null, metadata !"", i32 0, i64 64, i64 64, i64 0, i32 0, metadata !8} ; [ DW_TAG_pointer_type ] [line 0, size 64, align 64, offset 0] [from C]
+!30 = metadata !{i32 9, i32 0, metadata !3, null}
+!31 = metadata !{i32 10, i32 0, metadata !3, null}
+!32 = metadata !{i32 11, i32 0, metadata !3, null}
+!33 = metadata !{i32 14, i32 0, metadata !18, null}
+!34 = metadata !{i32 20, i32 0, metadata !19, null}
+!35 = metadata !{i32 25, i32 0, metadata !20, null}
+!36 = metadata !{i32 26, i32 0, metadata !20, null}
+!37 = metadata !{metadata !"dwarf-public-names.cpp", metadata !"/usr2/kparzysz/s.hex/t"}