Revert "[DEBUGINFO] Add flag for DWARF2 or less to use sections as references."

This reverts commit r326328 to remove checks for emission of certain
sections after discussion with Eric Christofer.

llvm-svn: 326436

llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp

@@ -270,20 +270,15 @@ void DwarfCompileUnit::addRange(RangeSpan Range) {
 
 void DwarfCompileUnit::initStmtList() {
   // Define start line table label for each Compile Unit.
-  MCSymbol *LineTableStartSym;
+  MCSymbol *LineTableStartSym =
-  const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
+      Asm->OutStreamer->getDwarfLineTableSymbol(getUniqueID());
-  if (DD->useSectionsAsReferences()) {
-    LineTableStartSym = TLOF.getDwarfLineSection()->getBeginSymbol();
-  } else {
-    LineTableStartSym =
-        Asm->OutStreamer->getDwarfLineTableSymbol(getUniqueID());
-  }
 
   // DW_AT_stmt_list is a offset of line number information for this
   // compile unit in debug_line section. For split dwarf this is
   // left in the skeleton CU and so not included.
   // The line table entries are not always emitted in assembly, so it
   // is not okay to use line_table_start here.
+  const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
   StmtListValue =
       addSectionLabel(getUnitDie(), dwarf::DW_AT_stmt_list, LineTableStartSym,
                       TLOF.getDwarfLineSection()->getBeginSymbol());
@@ -415,10 +410,9 @@ void DwarfCompileUnit::addScopeRangeList(DIE &ScopeDIE,
 
 void DwarfCompileUnit::attachRangesOrLowHighPC(
     DIE &Die, SmallVector<RangeSpan, 2> Ranges) {
-  if (Ranges.size() == 1 || DD->useSectionsAsReferences()) {
+  if (Ranges.size() == 1) {
-    const auto &front = Ranges.front();
+    const auto &single = Ranges.front();
-    const auto &back = Ranges.back();
+    attachLowHighPC(Die, single.getStart(), single.getEnd());
-    attachLowHighPC(Die, front.getStart(), back.getEnd());
   } else
     addScopeRangeList(Die, std::move(Ranges));
 }
@@ -840,7 +834,7 @@ void DwarfCompileUnit::createAbstractVariable(const DILocalVariable *Var,
 
 void DwarfCompileUnit::emitHeader(bool UseOffsets) {
   // Don't bother labeling the .dwo unit, as its offset isn't used.
-  if (!Skeleton && !DD->useSectionsAsReferences()) {
+  if (!Skeleton) {
     LabelBegin = Asm->createTempSymbol("cu_begin");
     Asm->OutStreamer->EmitLabel(LabelBegin);
   }
@@ -857,8 +851,7 @@ bool DwarfCompileUnit::hasDwarfPubSections() const {
   if (CUNode->getGnuPubnames())
     return true;
 
-  return DD->tuneForGDB() && !includeMinimalInlineScopes() &&
+  return DD->tuneForGDB() && !includeMinimalInlineScopes();
-         !DD->useSectionsAsReferences();
 }
 
 /// addGlobalName - Add a new global name to the compile unit.

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -123,13 +123,6 @@ DwarfInlinedStrings("dwarf-inlined-strings", cl::Hidden,
                             clEnumVal(Disable, "Disabled")),
                  cl::init(Default));
 
-static cl::opt<DefaultOnOff> DwarfSectionsAsReferences(
-    "dwarf-sections-as-references", cl::Hidden,
-    cl::desc("Use sections+offset as references rather than labels."),
-    cl::values(clEnumVal(Default, "Default for platform"),
-               clEnumVal(Enable, "Enabled"), clEnumVal(Disable, "Disabled")),
-    cl::init(Default));
-
 enum LinkageNameOption {
   DefaultLinkageNames,
   AllLinkageNames,
@@ -317,10 +310,6 @@ DwarfDebug::DwarfDebug(AsmPrinter *A, Module *M)
   // Use dwarf 4 by default if nothing is requested.
   DwarfVersion = DwarfVersion ? DwarfVersion : dwarf::DWARF_VERSION;
 
-  // Use sections as references in DWARF v2.
-  UseSectionsAsReferences =
-      DwarfVersion == 2 && DwarfSectionsAsReferences == Enable;
-
   // Work around a GDB bug. GDB doesn't support the standard opcode;
   // SCE doesn't support GNU's; LLDB prefers the standard opcode, which
   // is defined as of DWARF 3.
@@ -748,7 +737,7 @@ void DwarfDebug::finalizeModuleInfo() {
     // ranges for all subprogram DIEs for mach-o.
     DwarfCompileUnit &U = SkCU ? *SkCU : TheCU;
     if (unsigned NumRanges = TheCU.getRanges().size()) {
-      if (NumRanges > 1 && !useSectionsAsReferences())
+      if (NumRanges > 1)
         // A DW_AT_low_pc attribute may also be specified in combination with
         // DW_AT_ranges to specify the default base address for use in
         // location lists (see Section 2.6.2) and range lists (see Section
@@ -1576,13 +1565,7 @@ void DwarfDebug::emitDebugPubSection(bool GnuStyle, StringRef Name,
   Asm->EmitInt16(dwarf::DW_PUBNAMES_VERSION);
 
   Asm->OutStreamer->AddComment("Offset of Compilation Unit Info");
-  if (useSectionsAsReferences()) {
+  Asm->emitDwarfSymbolReference(TheU->getLabelBegin());
-    Asm->EmitLabelPlusOffset(TheU->getSection()->getBeginSymbol(),
-                             TheU->getDebugSectionOffset(),
-                             Asm->MAI->getCodePointerSize());
-  } else {
-    Asm->emitDwarfSymbolReference(TheU->getLabelBegin());
-  }
 
   Asm->OutStreamer->AddComment("Compilation Unit Length");
   Asm->EmitInt32(TheU->getLength());
@@ -1881,13 +1864,7 @@ void DwarfDebug::emitDebugARanges() {
     Asm->OutStreamer->AddComment("DWARF Arange version number");
     Asm->EmitInt16(dwarf::DW_ARANGES_VERSION);
     Asm->OutStreamer->AddComment("Offset Into Debug Info Section");
-    if (useSectionsAsReferences()) {
+    Asm->emitDwarfSymbolReference(CU->getLabelBegin());
-      Asm->EmitLabelPlusOffset(CU->getSection()->getBeginSymbol(),
-                               CU->getDebugSectionOffset(),
-                               Asm->MAI->getCodePointerSize());
-    } else {
-      Asm->emitDwarfSymbolReference(CU->getLabelBegin());
-    }
     Asm->OutStreamer->AddComment("Address Size (in bytes)");
     Asm->EmitInt8(PtrSize);
     Asm->OutStreamer->AddComment("Segment Size (in bytes)");

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h

@@ -258,10 +258,6 @@ class DwarfDebug : public DebugHandlerBase {
   /// Use inlined strings.
   bool UseInlineStrings = false;
 
-  /// True if the sections itself must be used as references and don't create
-  /// temp symbols inside DWARF sections.
-  bool UseSectionsAsReferences = false;
-
   /// DWARF5 Experimental Options
   /// @{
   bool HasDwarfAccelTables;
@@ -505,11 +501,6 @@ public:
   /// Returns whether to use inline strings.
   bool useInlineStrings() const { return UseInlineStrings; }
 
-  /// Returns whether to use sections as labels rather than temp symbols.
-  bool useSectionsAsReferences() const {
-    return UseSectionsAsReferences;
-  }
-
   // Experimental DWARF5 features.
 
   /// Returns whether or not to emit tables that dwarf consumers can

llvm/test/DebugInfo/X86/sections_as_references.ll

@@ -1,54 +0,0 @@
-; RUN: llc -filetype=asm -O0 -mtriple=x86_64-linux-gnu < %s -dwarf-sections-as-references=Enable -dwarf-inlined-strings=Enable -dwarf-version 2 | FileCheck %s
-
-; CHECK:      .file
-
-; CHECK-NOT:  .L
-
-; CHECK:      .section .debug_abbrev
-; CHECK-NOT:  DW_FORM_str{{p|x}}
-; CHECK-NOT: .L
-
-; CHECK:      .section .debug_info
-; CHECK-NOT:  .L
-; CHECK:      .short 2             # DWARF version number
-; CHECK-NOT:  .L
-; CHECK:      .long .debug_abbrev  # Offset Into Abbrev. Section
-; CHECK-NOT:  .L
-; CHECK:      .long .debug_line    # DW_AT_stmt_list
-; CHECK-NOT:  .L
-; CHECK:      .long .debug_abbrev  # Offset Into Abbrev. Section
-; CHECK-NOT:  .L
-; CHECK:      .long .debug_line    # DW_AT_stmt_list
-; CHECK-NOT:  .L
-; CHECK:      .quad .debug_info+{{[0-9]+}} # DW_AT_type
-; CHECK-NOT:  .L
-; CHECK:      .byte 0              # End Of Children Mark
-; CHECK-NOT:  .L
-
-source_filename = "test/DebugInfo/X86/sections_as_references.ll"
-
-%struct.foo = type { i8 }
-
-@f = global %struct.foo zeroinitializer, align 1, !dbg !0
-@g = global %struct.foo zeroinitializer, align 1, !dbg !6
-
-!llvm.dbg.cu = !{!9, !12}
-!llvm.module.flags = !{!14, !15}
-
-!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
-!1 = !DIGlobalVariable(name: "f", scope: null, file: !2, line: 2, type: !3, isLocal: false, isDefinition: true)
-!2 = !DIFile(filename: "tu1.cpp", directory: "/dir")
-!3 = !DICompositeType(tag: DW_TAG_structure_type, name: "foo", file: !4, line: 1, size: 8, align: 8, elements: !5, identifier: "_ZTS3foo")
-!4 = !DIFile(filename: "./hdr.h", directory: "/dir")
-!5 = !{}
-!6 = !DIGlobalVariableExpression(var: !7, expr: !DIExpression())
-!7 = !DIGlobalVariable(name: "g", scope: null, file: !8, line: 2, type: !3, isLocal: false, isDefinition: true)
-!8 = !DIFile(filename: "tu2.cpp", directory: "/dir")
-!9 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !2, producer: "clang", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !5, retainedTypes: !10, globals: !11, imports: !5)
-!10 = !{!3}
-!11 = !{!0}
-!12 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !8, producer: "clang", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !5, retainedTypes: !10, globals: !13, imports: !5)
-!13 = !{!6}
-!14 = !{i32 2, !"Dwarf Version", i32 2}
-!15 = !{i32 1, !"Debug Info Version", i32 3}
-