[DWARF5] Added support for emission of .debug_macro.dwo section

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

- DW_MACRO_start_file
- DW_MACRO_end_file
- DW_MACRO_define_strx
- DW_MACRO_undef_strx

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D78866

llvm/include/llvm/MC/MCObjectFileInfo.h

@@ -113,6 +113,7 @@ protected:
   MCSection *DwarfLocDWOSection = nullptr;
   MCSection *DwarfStrOffDWOSection = nullptr;
   MCSection *DwarfMacinfoDWOSection = nullptr;
+  MCSection *DwarfMacroDWOSection = nullptr;
 
   /// The DWARF v5 string offset and address table sections.
   MCSection *DwarfStrOffSection = nullptr;
@@ -309,6 +310,7 @@ public:
   MCSection *getDwarfLoclistsDWOSection() const {
     return DwarfLoclistsDWOSection;
   }
+  MCSection *getDwarfMacroDWOSection() const { return DwarfMacroDWOSection; }
   MCSection *getDwarfMacinfoDWOSection() const {
     return DwarfMacinfoDWOSection;
   }

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -1291,9 +1291,11 @@ void DwarfDebug::finalizeModuleInfo() {
     // attribute.
     if (CUNode->getMacros()) {
       if (getDwarfVersion() >= 5) {
-        // FIXME: Add support for DWARFv5 DW_AT_macros attribute for split
-        // case.
-        if (!useSplitDwarf())
+        if (useSplitDwarf())
+          TheCU.addSectionDelta(
+              TheCU.getUnitDie(), dwarf::DW_AT_macros, U.getMacroLabelBegin(),
+              TLOF.getDwarfMacroDWOSection()->getBeginSymbol());
+        else
           U.addSectionLabel(U.getUnitDie(), dwarf::DW_AT_macros,
                             U.getMacroLabelBegin(),
                             TLOF.getDwarfMacroSection()->getBeginSymbol());
@@ -3014,10 +3016,10 @@ void DwarfDebug::emitDebugMacinfo() {
 }
 
 void DwarfDebug::emitDebugMacinfoDWO() {
-  // FIXME: Add support for macro.dwo section.
-  if (getDwarfVersion() >= 5)
-    return;
-  emitDebugMacinfoImpl(Asm->getObjFileLowering().getDwarfMacinfoDWOSection());
+  auto &ObjLower = Asm->getObjFileLowering();
+  emitDebugMacinfoImpl(getDwarfVersion() >= 5
+                           ? ObjLower.getDwarfMacroDWOSection()
+                           : ObjLower.getDwarfMacinfoDWOSection());
 }
 
 // DWARF5 Experimental Separate Dwarf emitters.

llvm/lib/MC/MCObjectFileInfo.cpp

@@ -473,6 +473,8 @@ void MCObjectFileInfo::initELFMCObjectFileInfo(const Triple &T, bool Large) {
       Ctx->getELFSection(".debug_rnglists.dwo", DebugSecType, ELF::SHF_EXCLUDE);
   DwarfMacinfoDWOSection =
       Ctx->getELFSection(".debug_macinfo.dwo", DebugSecType, ELF::SHF_EXCLUDE);
+  DwarfMacroDWOSection =
+      Ctx->getELFSection(".debug_macro.dwo", DebugSecType, ELF::SHF_EXCLUDE);
 
   DwarfLoclistsDWOSection =
       Ctx->getELFSection(".debug_loclists.dwo", DebugSecType, ELF::SHF_EXCLUDE);
@@ -649,6 +651,11 @@ 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.dwo");
+  DwarfMacroDWOSection = Ctx->getCOFFSection(
+      ".debug_macro.dwo",
+      COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
+          COFF::IMAGE_SCN_MEM_READ,
+      SectionKind::getMetadata(), "debug_macro.dwo");
   DwarfInfoDWOSection = Ctx->getCOFFSection(
       ".debug_info.dwo",
       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |

llvm/test/DebugInfo/X86/debug-macro-dwo.ll

@@ -0,0 +1,49 @@
+; This test checks emission of .debug_macro.dwo section when
+; -gdwarf-5 -gsplit-dwarf -fdebug-macro is specified.
+
+; RUN: %llc_dwarf -dwarf-version=5 -O0 -filetype=obj \
+; RUN: -split-dwarf-file=foo.dwo < %s | llvm-dwarfdump -v - | FileCheck %s
+
+; CHECK-LABEL:  .debug_info contents:
+; CHECK: DW_AT_macros [DW_FORM_sec_offset] (0x00000000)
+
+; CHECK-LABEL:  .debug_macro.dwo contents:
+; CHECK-NEXT: 0x00000000:
+; CHECK-NEXT: macro header: version = 0x0005, flags = 0x02
+; 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_strx - 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_strx - lineno: 14 macro: YEA
+; CHECK-NEXT:   DW_MACRO_end_file
+; CHECK-NEXT:   DW_MACRO_undef_strx - 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 11.0.0", isOptimized: false, runtimeVersion: 0, splitDebugFilename: "test.dwo", 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 11.0.0"}