DebugInfo: Don't put fission type units in comdat sections.

Since type units in the dwo file are handled by a debug aware tool, they
don't need to leverage the ELF comdat grouping to implement
deduplication. Avoid creating all the .group sections for these as a
space optimization.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208930 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/MC/MCObjectFileInfo.h

@@ -122,6 +122,7 @@ protected:
 
   /// These are used for the Fission separate debug information files.
   const MCSection *DwarfInfoDWOSection;
+  const MCSection *DwarfTypesDWOSection;
   const MCSection *DwarfAbbrevDWOSection;
   const MCSection *DwarfStrDWOSection;
   const MCSection *DwarfLineDWOSection;
@@ -270,7 +271,9 @@ public:
     return DwarfInfoDWOSection;
   }
   const MCSection *getDwarfTypesSection(uint64_t Hash) const;
-  const MCSection *getDwarfTypesDWOSection(uint64_t Hash) const;
+  const MCSection *getDwarfTypesDWOSection() const {
+    return DwarfTypesDWOSection;
+  }
   const MCSection *getDwarfAbbrevDWOSection() const {
     return DwarfAbbrevDWOSection;
   }

lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -1637,9 +1637,12 @@ void DwarfDebug::emitSectionLabels() {
   // Dwarf sections base addresses.
   DwarfInfoSectionSym =
       emitSectionSym(Asm, TLOF.getDwarfInfoSection(), "section_info");
-  if (useSplitDwarf())
+  if (useSplitDwarf()) {
     DwarfInfoDWOSectionSym =
         emitSectionSym(Asm, TLOF.getDwarfInfoDWOSection(), "section_info_dwo");
+    DwarfTypesDWOSectionSym =
+        emitSectionSym(Asm, TLOF.getDwarfTypesDWOSection(), "section_types_dwo");
+  }
   DwarfAbbrevSectionSym =
       emitSectionSym(Asm, TLOF.getDwarfAbbrevSection(), "section_abbrev");
   if (useSplitDwarf())
@@ -2403,9 +2406,9 @@ void DwarfDebug::addDwarfTypeUnitType(DwarfCompileUnit &CU,
   bool TopLevelType = TypeUnitsUnderConstruction.empty();
   AddrPool.resetUsedFlag();
 
-  auto OwnedUnit =
-      make_unique<DwarfTypeUnit>(InfoHolder.getUnits().size(), CU, Asm, this,
-                                 &InfoHolder, getDwoLineTable(CU));
+  auto OwnedUnit = make_unique<DwarfTypeUnit>(
+      InfoHolder.getUnits().size() + TypeUnitsUnderConstruction.size(), CU, Asm,
+      this, &InfoHolder, getDwoLineTable(CU));
   DwarfTypeUnit &NewTU = *OwnedUnit;
   DIE &UnitDie = NewTU.getUnitDie();
   TU = &NewTU;
@@ -2418,13 +2421,14 @@ void DwarfDebug::addDwarfTypeUnitType(DwarfCompileUnit &CU,
   uint64_t Signature = makeTypeSignature(Identifier);
   NewTU.setTypeSignature(Signature);
 
-  if (!useSplitDwarf())
+  if (useSplitDwarf())
+    NewTU.initSection(Asm->getObjFileLowering().getDwarfTypesDWOSection(),
+                      DwarfTypesDWOSectionSym);
+  else {
     CU.applyStmtList(UnitDie);
-
-  NewTU.initSection(
-      useSplitDwarf()
-          ? Asm->getObjFileLowering().getDwarfTypesDWOSection(Signature)
-          : Asm->getObjFileLowering().getDwarfTypesSection(Signature));
+    NewTU.initSection(
+        Asm->getObjFileLowering().getDwarfTypesSection(Signature));
+  }
 
   NewTU.setType(NewTU.createTypeDIE(CTy));
 

lib/CodeGen/AsmPrinter/DwarfDebug.h

@@ -253,6 +253,7 @@ class DwarfDebug : public AsmPrinterHandler {
   MCSymbol *DwarfDebugLocSectionSym, *DwarfLineSectionSym, *DwarfAddrSectionSym;
   MCSymbol *FunctionBeginSym, *FunctionEndSym;
   MCSymbol *DwarfInfoDWOSectionSym, *DwarfAbbrevDWOSectionSym;
+  MCSymbol *DwarfTypesDWOSectionSym;
   MCSymbol *DwarfStrDWOSectionSym;
   MCSymbol *DwarfGnuPubNamesSectionSym, *DwarfGnuPubTypesSectionSym;
 

lib/CodeGen/AsmPrinter/DwarfUnit.h

@@ -577,6 +577,7 @@ public:
            sizeof(uint32_t);                               // Type DIE Offset
   }
   void initSection(const MCSection *Section);
+  using DwarfUnit::initSection;
   DwarfCompileUnit &getCU() override { return CU; }
 
 protected:

lib/MC/MCObjectFileInfo.cpp

@@ -537,6 +537,9 @@ void MCObjectFileInfo::InitELFMCObjectFileInfo(Triple T) {
   DwarfInfoDWOSection =
     Ctx->getELFSection(".debug_info.dwo", ELF::SHT_PROGBITS, 0,
                        SectionKind::getMetadata());
+  DwarfTypesDWOSection =
+    Ctx->getELFSection(".debug_types.dwo", ELF::SHT_PROGBITS, 0,
+                       SectionKind::getMetadata());
   DwarfAbbrevDWOSection =
     Ctx->getELFSection(".debug_abbrev.dwo", ELF::SHT_PROGBITS, 0,
                        SectionKind::getMetadata());
@@ -807,13 +810,6 @@ const MCSection *MCObjectFileInfo::getDwarfTypesSection(uint64_t Hash) const {
                             SectionKind::getMetadata(), 0, utostr(Hash));
 }
 
-const MCSection *
-MCObjectFileInfo::getDwarfTypesDWOSection(uint64_t Hash) const {
-  return Ctx->getELFSection(".debug_types.dwo", ELF::SHT_PROGBITS,
-                            ELF::SHF_GROUP, SectionKind::getMetadata(), 0,
-                            utostr(Hash));
-}
-
 void MCObjectFileInfo::InitEHFrameSection() {
   if (Env == IsMachO)
     EHFrameSection =

test/DebugInfo/X86/generate-odr-hash.ll

@@ -1,10 +1,12 @@
 ; REQUIRES: object-emission
 
-; RUN: llc %s -o %t -filetype=obj -O0 -generate-type-units -mtriple=x86_64-unknown-linux-gnu
+; RUN: llc < %s -o %t -filetype=obj -O0 -generate-type-units -mtriple=x86_64-unknown-linux-gnu
 ; RUN: llvm-dwarfdump %t | FileCheck --check-prefix=CHECK --check-prefix=SINGLE %s
+; RUN: llvm-readobj -s -t %t | FileCheck --check-prefix=OBJ_COMMON %s
 
-; RUN: llc %s -split-dwarf=Enable -o %t -filetype=obj -O0 -generate-type-units -mtriple=x86_64-unknown-linux-gnu
+; RUN: llc < %s -split-dwarf=Enable -o %t -filetype=obj -O0 -generate-type-units -mtriple=x86_64-unknown-linux-gnu
 ; RUN: llvm-dwarfdump %t | FileCheck --check-prefix=CHECK --check-prefix=FISSION %s
+; RUN: llvm-readobj -s -t %t | FileCheck --check-prefix=OBJ_COMMON --check-prefix=OBJ_FISSION %s
 
 ; Generated from bar.cpp:
 
@@ -161,6 +163,20 @@
 ; CHECK-NEXT: [[FLUFFY]] "echidna::capybara::mongoose::fluffy"
 ; CHECK-NEXT: [[WALRUS]] "walrus"
 
+; Make sure debug_types are in comdat groups. This could be more rigid to check
+; that they're the right comdat groups (each type in a separate comdat group,
+; etc)
+; OBJ_COMMON: Name: .debug_types (
+; OBJ_COMMON-NOT: }
+; OBJ_COMMON: SHF_GROUP
+
+; Fission type units don't go in comdat groups, since their linker is debug
+; aware it's handled using the debug info semantics rather than raw ELF object
+; semantics.
+; OBJ_FISSION: Name: .debug_types.dwo (
+; OBJ_FISSION-NOT: SHF_GROUP
+; OBJ_FISSION: }
+
 %struct.bar = type { i8 }
 %"class.echidna::capybara::mongoose::fluffy" = type { i32, i32 }
 %"struct.<anonymous namespace>::walrus" = type { i8 }