[DWARF5] Added support for emission of debug_macro section.

Summary:
This patch adds support for emission of following DWARFv5 macro forms
in .debug_macro section.

1. DW_MACRO_start_file
2. DW_MACRO_end_file
3. DW_MACRO_define_strp
4. DW_MACRO_undef_strp.

Reviewed By: dblaikie, ikudrin

Differential Revision: https://reviews.llvm.org/D72828

include/llvm/MC/MCObjectFileInfo.h

@@ -89,6 +89,7 @@ protected:
   MCSection *DwarfARangesSection = nullptr;
   MCSection *DwarfRangesSection = nullptr;
   MCSection *DwarfMacinfoSection = nullptr;
+  MCSection *DwarfMacroSection = nullptr;
   // The pubnames section is no longer generated by default.  The generation
   // can be enabled by a compiler flag.
   MCSection *DwarfPubNamesSection = nullptr;
@@ -275,6 +276,7 @@ public:
   MCSection *getDwarfRnglistsSection() const { return DwarfRnglistsSection; }
   MCSection *getDwarfLoclistsSection() const { return DwarfLoclistsSection; }
   MCSection *getDwarfMacinfoSection() const { return DwarfMacinfoSection; }
+  MCSection *getDwarfMacroSection() const { return DwarfMacroSection; }
 
   MCSection *getDwarfDebugNamesSection() const {
     return DwarfDebugNamesSection;

lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -1288,18 +1288,29 @@ void DwarfDebug::finalizeModuleInfo() {
     }
 
     auto *CUNode = cast<DICompileUnit>(P.first);
-    // If compile Unit has macros, emit "DW_AT_macro_info" attribute.
+    // If compile Unit has macros, emit "DW_AT_macro_info/DW_AT_macros"
+    // attribute.
     if (CUNode->getMacros()) {
-      if (useSplitDwarf())
+      if (getDwarfVersion() >= 5) {
-        TheCU.addSectionDelta(TheCU.getUnitDie(), dwarf::DW_AT_macro_info,
+        // FIXME: Add support for DWARFv5 DW_AT_macros attribute for split
+        // case.
+        if (!useSplitDwarf())
+          U.addSectionLabel(U.getUnitDie(), dwarf::DW_AT_macros,
                             U.getMacroLabelBegin(),
-                            TLOF.getDwarfMacinfoDWOSection()->getBeginSymbol());
+                            TLOF.getDwarfMacroSection()->getBeginSymbol());
-      else
+      } else {
-        U.addSectionLabel(U.getUnitDie(), dwarf::DW_AT_macro_info,
+        if (useSplitDwarf())
-                          U.getMacroLabelBegin(),
+          TheCU.addSectionDelta(
-                          TLOF.getDwarfMacinfoSection()->getBeginSymbol());
+              TheCU.getUnitDie(), dwarf::DW_AT_macro_info,
+              U.getMacroLabelBegin(),
+              TLOF.getDwarfMacinfoDWOSection()->getBeginSymbol());
+        else
+          U.addSectionLabel(U.getUnitDie(), dwarf::DW_AT_macro_info,
+                            U.getMacroLabelBegin(),
+                            TLOF.getDwarfMacinfoSection()->getBeginSymbol());
+      }
+    }
     }
-  }
 
   // Emit all frontend-produced Skeleton CUs, i.e., Clang modules.
   for (auto *CUNode : MMI->getModule()->debug_compile_units())
@@ -1355,7 +1366,7 @@ void DwarfDebug::endModule() {
   // Emit info into a debug macinfo.dwo section.
     emitDebugMacinfoDWO();
   else
-  // Emit info into a debug macinfo section.
+    // Emit info into a debug macinfo/macro section.
     emitDebugMacinfo();
 
   emitDebugStr();
@@ -2854,6 +2865,27 @@ void DwarfDebug::emitDebugRangesDWO() {
                       Asm->getObjFileLowering().getDwarfRnglistsDWOSection());
 }
 
+/// Emit the header of a DWARF 5 macro section.
+static void emitMacroHeader(AsmPrinter *Asm, const DwarfDebug &DD,
+                            const DwarfCompileUnit &CU) {
+  enum HeaderFlagMask {
+#define HANDLE_MACRO_FLAG(ID, NAME) MACRO_FLAG_##NAME = ID,
+#include "llvm/BinaryFormat/Dwarf.def"
+  };
+  uint8_t Flags = 0;
+  Asm->OutStreamer->AddComment("Macro information version");
+  Asm->emitInt16(5);
+  // We are setting Offset and line offset flags unconditionally here,
+  // since we're only supporting DWARF32 and line offset should be mostly
+  // present.
+  // FIXME: Add support for DWARF64.
+  Flags |= MACRO_FLAG_DEBUG_LINE_OFFSET;
+  Asm->OutStreamer->AddComment("Flags: 32 bit, debug_line_offset present");
+  Asm->emitInt8(Flags);
+  Asm->OutStreamer->AddComment("debug_line_offset");
+  Asm->OutStreamer->emitSymbolValue(CU.getLineTableStartSym(), /*Size=*/4);
+}
+
 void DwarfDebug::handleMacroNodes(DIMacroNodeArray Nodes, DwarfCompileUnit &U) {
   for (auto *MN : Nodes) {
     if (auto *M = dyn_cast<DIMacro>(MN))
@@ -2866,26 +2898,75 @@ void DwarfDebug::handleMacroNodes(DIMacroNodeArray Nodes, DwarfCompileUnit &U) {
 }
 
 void DwarfDebug::emitMacro(DIMacro &M) {
-  Asm->emitULEB128(M.getMacinfoType());
-  Asm->emitULEB128(M.getLine());
   StringRef Name = M.getName();
   StringRef Value = M.getValue();
-  Asm->OutStreamer->emitBytes(Name);
+  bool UseMacro = getDwarfVersion() >= 5;
-  if (!Value.empty()) {
+
-    // There should be one space between macro name and macro value.
+  if (UseMacro) {
-    Asm->emitInt8(' ');
+    unsigned Type = M.getMacinfoType() == dwarf::DW_MACINFO_define
-    Asm->OutStreamer->emitBytes(Value);
+                        ? dwarf::DW_MACRO_define_strp
+                        : dwarf::DW_MACRO_undef_strp;
+    Asm->OutStreamer->AddComment(dwarf::MacroString(Type));
+    Asm->emitULEB128(Type);
+    Asm->OutStreamer->AddComment("Line Number");
+    Asm->emitULEB128(M.getLine());
+    Asm->OutStreamer->AddComment("Macro String");
+    if (!Value.empty())
+      Asm->OutStreamer->emitSymbolValue(
+          this->InfoHolder.getStringPool()
+              .getEntry(*Asm, (Name + " " + Value).str())
+              .getSymbol(),
+          4);
+    else
+      // DW_MACRO_undef_strp doesn't have a value, so just emit the macro
+      // string.
+      Asm->OutStreamer->emitSymbolValue(this->InfoHolder.getStringPool()
+                                            .getEntry(*Asm, (Name).str())
+                                            .getSymbol(),
+                                        4);
+  } else {
+    Asm->OutStreamer->AddComment(dwarf::MacinfoString(M.getMacinfoType()));
+    Asm->emitULEB128(M.getMacinfoType());
+    Asm->OutStreamer->AddComment("Line Number");
+    Asm->emitULEB128(M.getLine());
+    Asm->OutStreamer->AddComment("Macro String");
+    Asm->OutStreamer->emitBytes(Name);
+    if (!Value.empty()) {
+      // There should be one space between macro name and macro value.
+      Asm->emitInt8(' ');
+      Asm->OutStreamer->AddComment("Macro Value=");
+      Asm->OutStreamer->emitBytes(Value);
+    }
+    Asm->emitInt8('\0');
   }
-  Asm->emitInt8('\0');
+}
+
+void DwarfDebug::emitMacroFileImpl(
+    DIMacroFile &F, DwarfCompileUnit &U, unsigned StartFile, unsigned EndFile,
+    StringRef (*MacroFormToString)(unsigned Form)) {
+
+  Asm->OutStreamer->AddComment(MacroFormToString(StartFile));
+  Asm->emitULEB128(StartFile);
+  Asm->OutStreamer->AddComment("Line Number");
+  Asm->emitULEB128(F.getLine());
+  Asm->OutStreamer->AddComment("File Number");
+  Asm->emitULEB128(U.getOrCreateSourceID(F.getFile()));
+  handleMacroNodes(F.getElements(), U);
+  Asm->OutStreamer->AddComment(MacroFormToString(EndFile));
+  Asm->emitULEB128(EndFile);
 }
 
 void DwarfDebug::emitMacroFile(DIMacroFile &F, DwarfCompileUnit &U) {
+  // DWARFv5 macro and DWARFv4 macinfo share some common encodings,
+  // so for readibility/uniformity, We are explicitly emitting those.
   assert(F.getMacinfoType() == dwarf::DW_MACINFO_start_file);
-  Asm->emitULEB128(dwarf::DW_MACINFO_start_file);
+  bool UseMacro = getDwarfVersion() >= 5;
-  Asm->emitULEB128(F.getLine());
+  if (UseMacro)
-  Asm->emitULEB128(U.getOrCreateSourceID(F.getFile()));
+    emitMacroFileImpl(F, U, dwarf::DW_MACRO_start_file,
-  handleMacroNodes(F.getElements(), U);
+                      dwarf::DW_MACRO_end_file, dwarf::MacroString);
-  Asm->emitULEB128(dwarf::DW_MACINFO_end_file);
+  else
+    emitMacroFileImpl(F, U, dwarf::DW_MACINFO_start_file,
+                      dwarf::DW_MACINFO_end_file, dwarf::MacinfoString);
 }
 
 void DwarfDebug::emitDebugMacinfoImpl(MCSection *Section) {
@@ -2899,18 +2980,26 @@ void DwarfDebug::emitDebugMacinfoImpl(MCSection *Section) {
       continue;
     Asm->OutStreamer->SwitchSection(Section);
     Asm->OutStreamer->emitLabel(U.getMacroLabelBegin());
+    if (getDwarfVersion() >= 5)
+      emitMacroHeader(Asm, *this, U);
     handleMacroNodes(Macros, U);
     Asm->OutStreamer->AddComment("End Of Macro List Mark");
     Asm->emitInt8(0);
   }
 }
 
-/// Emit macros into a debug macinfo section.
+/// Emit macros into a debug macinfo/macro section.
 void DwarfDebug::emitDebugMacinfo() {
-  emitDebugMacinfoImpl(Asm->getObjFileLowering().getDwarfMacinfoSection());
+  auto &ObjLower = Asm->getObjFileLowering();
+  emitDebugMacinfoImpl(getDwarfVersion() >= 5
+                           ? ObjLower.getDwarfMacroSection()
+                           : ObjLower.getDwarfMacinfoSection());
 }
 
 void DwarfDebug::emitDebugMacinfoDWO() {
+  // FIXME: Add support for macro.dwo section.
+  if (getDwarfVersion() >= 5)
+    return;
   emitDebugMacinfoImpl(Asm->getObjFileLowering().getDwarfMacinfoDWOSection());
 }
 

lib/CodeGen/AsmPrinter/DwarfDebug.h

@@ -528,6 +528,9 @@ class DwarfDebug : public DebugHandlerBase {
   void emitDebugMacinfoImpl(MCSection *Section);
   void emitMacro(DIMacro &M);
   void emitMacroFile(DIMacroFile &F, DwarfCompileUnit &U);
+  void emitMacroFileImpl(DIMacroFile &F, DwarfCompileUnit &U,
+                         unsigned StartFile, unsigned EndFile,
+                         StringRef (*MacroFormToString)(unsigned Form));
   void handleMacroNodes(DIMacroNodeArray Nodes, DwarfCompileUnit &U);
 
   /// DWARF 5 Experimental Split Dwarf Emitters

lib/MC/MCObjectFileInfo.cpp

@@ -276,6 +276,9 @@ void MCObjectFileInfo::initMachOMCObjectFileInfo(const Triple &T) {
   DwarfMacinfoSection =
       Ctx->getMachOSection("__DWARF", "__debug_macinfo", MachO::S_ATTR_DEBUG,
                            SectionKind::getMetadata(), "debug_macinfo");
+  DwarfMacroSection =
+      Ctx->getMachOSection("__DWARF", "__debug_macro", MachO::S_ATTR_DEBUG,
+                           SectionKind::getMetadata(), "debug_macro");
   DwarfDebugInlineSection =
       Ctx->getMachOSection("__DWARF", "__debug_inlined", MachO::S_ATTR_DEBUG,
                            SectionKind::getMetadata());
@@ -427,6 +430,7 @@ void MCObjectFileInfo::initELFMCObjectFileInfo(const Triple &T, bool Large) {
       Ctx->getELFSection(".debug_ranges", DebugSecType, 0);
   DwarfMacinfoSection =
       Ctx->getELFSection(".debug_macinfo", DebugSecType, 0);
+  DwarfMacroSection = Ctx->getELFSection(".debug_macro", DebugSecType, 0);
 
   // DWARF5 Experimental Debug Info
 
@@ -635,6 +639,11 @@ void MCObjectFileInfo::initCOFFMCObjectFileInfo(const Triple &T) {
       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
           COFF::IMAGE_SCN_MEM_READ,
       SectionKind::getMetadata(), "debug_macinfo");
+  DwarfMacroSection = Ctx->getCOFFSection(
+      ".debug_macro",
+      COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
+          COFF::IMAGE_SCN_MEM_READ,
+      SectionKind::getMetadata(), "debug_macro");
   DwarfMacinfoDWOSection = Ctx->getCOFFSection(
       ".debug_macinfo.dwo",
       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
@@ -771,6 +780,8 @@ void MCObjectFileInfo::initWasmMCObjectFileInfo(const Triple &T) {
       Ctx->getWasmSection(".debug_ranges", SectionKind::getMetadata());
   DwarfMacinfoSection =
       Ctx->getWasmSection(".debug_macinfo", SectionKind::getMetadata());
+  DwarfMacroSection =
+      Ctx->getWasmSection(".debug_macro", SectionKind::getMetadata());
   DwarfCUIndexSection = Ctx->getWasmSection(".debug_cu_index", SectionKind::getMetadata());
   DwarfTUIndexSection = Ctx->getWasmSection(".debug_tu_index", SectionKind::getMetadata());
   DwarfInfoSection =

test/DebugInfo/X86/debug-macro-v5.ll

@@ -0,0 +1,48 @@
+; This test checks emission of .debug_macro section when
+; -gdwarf-5 -fdebug-macro is specified.
+
+; RUN: %llc_dwarf -dwarf-version=5 -O0 -filetype=obj < %s | llvm-dwarfdump -v - | FileCheck %s
+
+; CHECK-LABEL:  .debug_info contents:
+; CHECK: DW_AT_macros [DW_FORM_sec_offset] (0x00000000)
+
+; CHECK-LABEL:  .debug_macro contents:
+; CHECK-NEXT: 0x00000000:
+; CHECK-NEXT: macro header: version = 0x0005, flags = 0x02, debug_line_offset = 0x0000
+; CHECK-NEXT: DW_MACRO_start_file - lineno: 0 filenum: 0
+; CHECK-NEXT:   DW_MACRO_start_file - lineno: 1 filenum: 1
+; CHECK-NEXT:     DW_MACRO_define_strp - lineno: 1 macro: FOO 5
+; CHECK-NEXT:   DW_MACRO_end_file
+; CHECK-NEXT:   DW_MACRO_start_file - lineno: 2 filenum: 2
+; CHECK-NEXT:     DW_MACRO_undef_strp - lineno: 14 macro: YEA
+; CHECK-NEXT:   DW_MACRO_end_file
+; CHECK-NEXT:   DW_MACRO_undef_strp - lineno: 14 macro: YEA
+; CHECK-NEXT: DW_MACRO_end_file
+
+; ModuleID = 'test.c'
+source_filename = "test.c"
+target datalayout = "e-m:e-p200:32:32-p201:32:32-p202:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!14, !15, !16}
+!llvm.ident = !{!17}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 10.0.0", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, macros: !3, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "test.c", directory: "/home/", checksumkind: CSK_MD5, checksum: "ef6a7032e0c7ceeef614583f2c00dc80")
+!2 = !{}
+!3 = !{!4}
+!4 = !DIMacroFile(file: !1, nodes: !5)
+!5 = !{!6, !10, !13}
+!6 = !DIMacroFile(line: 1, file: !7, nodes: !8)
+!7 = !DIFile(filename: "./foo.h", directory: "/home/", checksumkind: CSK_MD5, checksum: "0f0cd0e15b44f49d3944992c8dc28661")
+!8 = !{!9}
+!9 = !DIMacro(type: DW_MACINFO_define, line: 1, name: "FOO", value: "5")
+!10 = !DIMacroFile(line: 2, file: !11, nodes: !12)
+!11 = !DIFile(filename: "./bar.h", directory: "/home/", checksumkind: CSK_MD5, checksum: "bf4b34c263eaaa1d7085c18243b8d100")
+!12 = !{!13}
+!13 = !DIMacro(type: DW_MACINFO_undef, line: 14, name: "YEA")
+!14 = !{i32 7, !"Dwarf Version", i32 5}
+!15 = !{i32 2, !"Debug Info Version", i32 3}
+!16 = !{i32 1, !"wchar_size", i32 4}
+!17 = !{!"clang version 10.0.0"}