Move the sysroot attribute from DIModule to DICompileUnit

[aprantl]

Summary

This addresses point 1 of PR44213. (https://bugs.llvm.org/show_bug.cgi?id=44213).

The DW_AT_LLVM_sysroot attribute is used for Clang module debug info, to allow LLDB to import a Clang module from source. Currently it is part of each DW_TAG_module, however, it is the same for all modules in a compile unit. It is more efficient and less ambiguous to store it once in the DW_TAG_compile_unit.

This should have no effect on DWARF consumers other than LLDB.

[aprantl]

llvm/lib/Bitcode/Writer/BitcodeWriter.cpp

1664

@dblaikie This is a workaround for the bug I documented in https://reviews.llvm.org/D54242#inline-649516

[aprantl]

Forgot to include the LLDB patch.

[teemperor]

llvm/bindings/go/llvm/dibuilder.go

120

indentation seems of?

148

indentation seems of?

llvm/include/llvm/IR/DebugInfoMetadata.h

1282

double empty line?

[aprantl]

Address feedback from Raphael.

[aprantl]

Removed workaround for the bug @dbalikie fixed in https://reviews.llvm.org/rGc51b45e32ef7f35c11891f60871aa9c2c04cd991

[aprantl]

Ping @debug-info / @dblaikie for a review.

[aprantl]

@dblaikie: I just saw you reverted https://reviews.llvm.org/rGc51b45e32ef7f35c11891f60871aa9c2c04cd991 ? What happened?

[dblaikie]

In D71732#1812937, @aprantl wrote:

@dblaikie: I just saw you reverted https://reviews.llvm.org/rGc51b45e32ef7f35c11891f60871aa9c2c04cd991 ? What happened?

As mentioned in the revert: https://reviews.llvm.org/rGb350c666ab65b7585bc58301b03d2b46dc6b0504

Some mysterious CFI failures I haven't looked into yet, but were pretty clearly blamed on this change & went away with a revert.

[aprantl]

Some mysterious CFI failures I haven't looked into yet, but were pretty clearly blamed on this change & went away with a revert.

Because the flag was previously not (de)serialized and now shows up in LTO builds where it was dropped before?
Well I guess I can serialize false for now without preventing this from getting fixed.

Any opinions on this patch otherwise?

[dblaikie]

In D71732#1813229, @aprantl wrote:

Some mysterious CFI failures I haven't looked into yet, but were pretty clearly blamed on this change & went away with a revert.

Because the flag was previously not (de)serialized and now shows up in LTO builds where it was dropped before?

Maybe, but don't see how that'd turn up anything interesting in CFI behavior - again, no one's turning this flag on...

Well I guess I can serialize false for now without preventing this from getting fixed.

Any opinions on this patch otherwise?

Seems alright - but I'd like to understand it a bit better. Looks like this'll add the attribute to every (.o - so skeleton with Split DWARF, or the normal/unit with non-split) CU, where previously it was only in DIModules which were only emitted with -gmodules? What's it used for? Could it be put in the full unit, rather than the skeleton unit? Could it be only emitted when tuning for lldb?

[aprantl]

In D71732#1820401, @dblaikie wrote:

In D71732#1813229, @aprantl wrote:

Some mysterious CFI failures I haven't looked into yet, but were pretty clearly blamed on this change & went away with a revert.

Because the flag was previously not (de)serialized and now shows up in LTO builds where it was dropped before?

Maybe, but don't see how that'd turn up anything interesting in CFI behavior - again, no one's turning this flag on...

Well I guess I can serialize false for now without preventing this from getting fixed.

Any opinions on this patch otherwise?

Seems alright - but I'd like to understand it a bit better. Looks like this'll add the attribute to every (.o - so skeleton with Split DWARF, or the normal/unit with non-split) CU, where previously it was only in DIModules which were only emitted with -gmodules? What's it used for? Could it be put in the full unit, rather than the skeleton unit? Could it be only emitted when tuning for lldb?

Yes and yes. I'll update the patch. The attribute helps LLDB to construct a Clang compiler invocation that can be used to import Clang modules from source so you have access to the entire module (not just what was used and thus put into the debug info) in the expression evaluator.

[aprantl]

Addressed feedback from @dblaikie :

• sysroot is now an LLDB tuning setting
• attribute moved from skeleton to .dwo unit

[dblaikie]

clang/test/CodeGen/debug-info-sysroot.c

7

side note: debugger tuning is not in the IR at all - so it probably doesn't work during LTO without passing it to the backend compile(s)/link step, somehow (not sure if any command line syntax supports that, though - maybe -mllvm somehow). At some point I'm guessing it should be added as module level metadata.

llvm/lib/Bitcode/Reader/MetadataLoader.cpp

1421

Probably might as well phrase this as bounds - size < 5 || size > 6 - then any changes can modify the upper bound rather than rephrasing this then.

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

839–840

Yeah, shouldn't this use the parameter DIUnit's SysRoot? Rather than needing/using a member of DwarfDebug?

891

This looks suspicious - if SysRoot can vary per DICompileUnit, what's the e meaning of using one of those DICompileUnit's SysRoot on DwarfDebug which is cross-CU?

[aprantl]

• removed copyied&pasted sysroot member from DwarfDebug
• address feedback in MetadataLoader

[aprantl]

Any other comments?

[dblaikie]

Looks good - thanks!

clang/lib/CodeGen/CGDebugInfo.cpp

void CGDebugInfo::CreateCompileUnit() {
   // DW_AT_comp_dir (the compilation directory), even if the source
   // file was specified with an absolute path.
   if (CSKind)
     CSInfo.emplace(*CSKind, Checksum);
   llvm::DIFile *CUFile = DBuilder.createFile(
       remapDIPath(MainFileName), remapDIPath(getCurrentDirname()), CSInfo,
       getSource(SM, SM.getMainFileID()));
 
+  StringRef Sysroot;
+  if (CGM.getCodeGenOpts().getDebuggerTuning() == llvm::DebuggerKind::LLDB)
+    Sysroot = CGM.getHeaderSearchOpts().Sysroot;
+
   // Create new compile unit.
   TheCU = DBuilder.createCompileUnit(
       LangTag, CUFile, CGOpts.EmitVersionIdentMetadata ? Producer : "",
       LO.Optimize || CGOpts.PrepareForLTO || CGOpts.PrepareForThinLTO,
       CGOpts.DwarfDebugFlags, RuntimeVers, CGOpts.SplitDwarfFile, EmissionKind,
       DwoId, CGOpts.SplitDwarfInlining, CGOpts.DebugInfoForProfiling,
       CGM.getTarget().getTriple().isNVPTX()
           ? llvm::DICompileUnit::DebugNameTableKind::None
           : static_cast<llvm::DICompileUnit::DebugNameTableKind>(
                 CGOpts.DebugNameTable),
-      CGOpts.DebugRangesBaseAddress);
+      CGOpts.DebugRangesBaseAddress, Sysroot);
 }
 
 llvm::DIType *CGDebugInfo::CreateType(const BuiltinType *BT) {
   llvm::dwarf::TypeKind Encoding;
   StringRef BTName;
   switch (BT->getKind()) {
 #define BUILTIN_TYPE(Id, SingletonId)
 #define PLACEHOLDER_TYPE(Id, SingletonId) case BuiltinType::Id:
CGDebugInfo::getOrCreateModuleRef(ExternalASTSource::ASTSourceDescriptor Mod,
 
   llvm::DIModule *Parent =
       IsRootModule ? nullptr
                    : getOrCreateModuleRef(
                          ExternalASTSource::ASTSourceDescriptor(*M->Parent),
                          CreateSkeletonCU);
   llvm::DIModule *DIMod =
       DBuilder.createModule(Parent, Mod.getModuleName(), ConfigMacros,
-                            Mod.getPath(), CGM.getHeaderSearchOpts().Sysroot);
+                            Mod.getPath());
   ModuleCache[M].reset(DIMod);
   return DIMod;
 }
 
 llvm::DIType *CGDebugInfo::CreateTypeDefinition(const ObjCInterfaceType *Ty,
                                                 llvm::DIFile *Unit) {
   ObjCInterfaceDecl *ID = Ty->getDecl();
   llvm::DIFile *DefUnit = getOrCreateFile(ID->getLocation());

clang/test/CodeGen/debug-info-sysroot.c

+// RUN: %clang_cc1 -debug-info-kind=limited -triple %itanium_abi_triple \
+// RUN:   %s -isysroot /CLANG_SYSROOT -emit-llvm -o - \
+// RUN:   -debugger-tuning=lldb | FileCheck %s --check-prefix=LLDB
+// RUN: %clang_cc1 -debug-info-kind=limited -triple %itanium_abi_triple \
+// RUN:   %s -isysroot /CLANG_SYSROOT -emit-llvm -o - \
+// RUN:   -debugger-tuning=gdb | FileCheck %s --check-prefix=GDB
+
+void foo() {}
+
+// The sysroot is an LLDB-tuning-specific attribute.
+
+// LLDB: distinct !DICompileUnit({{.*}}sysroot: "/CLANG_SYSROOT"
+// GDB: distinct !DICompileUnit(
+// GDB-NOT: sysroot: "/CLANG_SYSROOT"
+

clang/test/CodeGen/debug-nvptx.c

 // RUN: %clang_cc1 -triple nvptx-unknown-unknown -S -o - -debug-info-kind=limited %s -emit-llvm | FileCheck %s
 
-// CHECK: DICompileUnit({{.*}}, nameTableKind: None)
+// CHECK: DICompileUnit({{.*}}, nameTableKind: None
 
 void f1(void) {
 }

clang/test/Modules/debug-info-moduleimport.m

 // RUN: rm -rf %t
 // RUN: %clang_cc1 -debug-info-kind=limited -fmodules -DGREETING="Hello World" -UNDEBUG -fimplicit-module-maps -fmodules-cache-path=%t %s -I %S/Inputs -isysroot /tmp/.. -I %t -emit-llvm -o - | FileCheck %s --check-prefix=NOIMPORT
 
 // NOIMPORT-NOT: !DIImportedEntity
 // NOIMPORT-NOT: !DIModule
 
 // RUN: rm -rf %t
 // RUN: %clang_cc1 -debug-info-kind=limited -fmodules -DGREETING="Hello World" -UNDEBUG -fimplicit-module-maps -fmodules-cache-path=%t %s -I %S/Inputs -isysroot /tmp/.. -I %t -emit-llvm -debugger-tuning=lldb -o - | FileCheck %s
 
 // CHECK: ![[CU:.*]] = distinct !DICompileUnit
+// CHECK-SAME:  sysroot: "/tmp/..")
 @import DebugObjC;
 // CHECK: !DIImportedEntity(tag: DW_TAG_imported_declaration, scope: ![[CU]],
 // CHECK-SAME:              entity: ![[MODULE:.*]], file: ![[F:[0-9]+]],
 // CHECK-SAME:              line: [[@LINE-3]])
 // CHECK: ![[MODULE]] = !DIModule(scope: null, name: "DebugObjC",
 // CHECK-SAME:  configMacros: "\22-DGREETING=Hello World\22 \22-UNDEBUG\22",
-// CHECK-SAME:  includePath: "{{.*}}test{{.*}}Modules{{.*}}Inputs",
-// CHECK-SAME:  sysroot: "/tmp/..")
+// CHECK-SAME:  includePath: "{{.*}}test{{.*}}Modules{{.*}}Inputs"
 // CHECK: ![[F]] = !DIFile(filename: {{.*}}debug-info-moduleimport.m
 
 // RUN: %clang_cc1 -debug-info-kind=limited -fmodules -fimplicit-module-maps -fmodules-cache-path=%t \
 // RUN:   %s -I %S/Inputs -isysroot /tmp/.. -I %t -emit-llvm -o - \
 // RUN:     | FileCheck %s --check-prefix=NO-SKEL-CHECK
 // NO-SKEL-CHECK: distinct !DICompileUnit
 // NO-SKEL-CHECK-NOT: distinct !DICompileUnit
 
 // RUN: %clang_cc1 -debug-info-kind=limited -fmodules -fimplicit-module-maps -fmodules-cache-path=%t \
 // RUN:   -fmodule-format=obj -dwarf-ext-refs \
 // RUN:   %s -I %S/Inputs -isysroot /tmp/.. -I %t -emit-llvm -o - \
 // RUN:     | FileCheck %s --check-prefix=SKEL-CHECK
 // SKEL-CHECK: distinct !DICompileUnit
 // SKEL-CHECK: distinct !DICompileUnit{{.*}}dwoId

lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp

if (const char *name =
         if (const char *name =
                 parent_die.GetAttributeValueAsString(DW_AT_name, nullptr))
           module.path.push_back(ConstString(name));
       }
       std::reverse(module.path.begin(), module.path.end());
       if (const char *include_path = module_die.GetAttributeValueAsString(
               DW_AT_LLVM_include_path, nullptr))
         module.search_path = ConstString(include_path);
-      if (const char *sysroot = module_die.GetAttributeValueAsString(
+      if (const char *sysroot = dwarf_cu->DIE().GetAttributeValueAsString(
               DW_AT_LLVM_sysroot, nullptr))
         module.sysroot = ConstString(sysroot);
       imported_modules.push_back(module);
     }
   }
   return true;
 }
 

llvm/bindings/go/llvm/dibuilder.go

 type DICompileUnit struct {
   Language       DwarfLang
   File           string
   Dir            string
   Producer       string
   Optimized      bool
   Flags          string
   RuntimeVersion int
+  SysRoot        string
 }
 
 // CreateCompileUnit creates compile unit debug metadata.
 func (d *DIBuilder) CreateCompileUnit(cu DICompileUnit) Metadata {
   file := C.CString(cu.File)
   defer C.free(unsafe.Pointer(file))
   dir := C.CString(cu.Dir)
   defer C.free(unsafe.Pointer(dir))
   producer := C.CString(cu.Producer)
   defer C.free(unsafe.Pointer(producer))
   flags := C.CString(cu.Flags)
   defer C.free(unsafe.Pointer(flags))
+  sysroot := C.CString(cu.SysRoot)
+  defer C.free(unsafe.Pointer(sysroot))
   result := C.LLVMDIBuilderCreateCompileUnit(
     d.ref,
     C.LLVMDWARFSourceLanguage(cu.Language),
     C.LLVMDIBuilderCreateFile(d.ref, file, C.size_t(len(cu.File)), dir, C.size_t(len(cu.Dir))),
     producer, C.size_t(len(cu.Producer)),
     C.LLVMBool(boolToCInt(cu.Optimized)),
     flags, C.size_t(len(cu.Flags)),
     C.unsigned(cu.RuntimeVersion),
     /*SplitName=*/ nil, 0,
     C.LLVMDWARFEmissionFull,
     /*DWOId=*/ 0,
     /*SplitDebugInlining*/ C.LLVMBool(boolToCInt(true)),
     /*DebugInfoForProfiling*/ C.LLVMBool(boolToCInt(false)),
+    sysroot,
   )
   return Metadata{C: result}
 }
 
 // CreateFile creates file debug metadata.
 func (d *DIBuilder) CreateFile(filename, dir string) Metadata {
   cfilename := C.CString(filename)
   defer C.free(unsafe.Pointer(cfilename))

llvm/include/llvm-c/DebugInfo.h

  * \param SplitName     The name of the file that we'll split debug info
  *                      out into.
  * \param SplitNameLen  The length of the C string passed to \c SplitName.
  * \param Kind          The kind of debug information to generate.
  * \param DWOId         The DWOId if this is a split skeleton compile unit.
  * \param SplitDebugInlining    Whether to emit inline debug info.
  * \param DebugInfoForProfiling Whether to emit extra debug info for
  *                              profile collection.
+ * \param SysRoot         The Clang system root (value of -isysroot).
+ * \param SysRootLen      The length of the C string passed to \c SysRoot.
  */
 LLVMMetadataRef LLVMDIBuilderCreateCompileUnit(
     LLVMDIBuilderRef Builder, LLVMDWARFSourceLanguage Lang,
     LLVMMetadataRef FileRef, const char *Producer, size_t ProducerLen,
     LLVMBool isOptimized, const char *Flags, size_t FlagsLen,
     unsigned RuntimeVer, const char *SplitName, size_t SplitNameLen,
     LLVMDWARFEmissionKind Kind, unsigned DWOId, LLVMBool SplitDebugInlining,
-    LLVMBool DebugInfoForProfiling);
+    LLVMBool DebugInfoForProfiling, const char *SysRoot, size_t SysRootLen);
 
 /**
  * Create a file descriptor to hold debugging information for a file.
  * \param Builder      The \c DIBuilder.
  * \param Filename     File name.
  * \param FilenameLen  The length of the C string passed to \c Filename.
  * \param Directory    Directory.
  * \param DirectoryLen The length of the C string passed to \c Directory.

  * \param ParentScope     The parent scope containing this module declaration.
  * \param Name            Module name.
  * \param NameLen         The length of the C string passed to \c Name.
  * \param ConfigMacros    A space-separated shell-quoted list of -D macro
                           definitions as they would appear on a command line.
  * \param ConfigMacrosLen The length of the C string passed to \c ConfigMacros.
  * \param IncludePath     The path to the module map file.
  * \param IncludePathLen  The length of the C string passed to \c IncludePath.
- * \param SysRoot         The Clang system root (value of -isysroot).
- * \param SysRootLen      The length of the C string passed to \c SysRoot.
  */
 LLVMMetadataRef
 LLVMDIBuilderCreateModule(LLVMDIBuilderRef Builder, LLVMMetadataRef ParentScope,
                           const char *Name, size_t NameLen,
                           const char *ConfigMacros, size_t ConfigMacrosLen,
-                          const char *IncludePath, size_t IncludePathLen,
-                          const char *SysRoot, size_t SysRootLen);
+                          const char *IncludePath, size_t IncludePathLen);
 
 /**
  * Creates a new descriptor for a namespace with the specified parent scope.
  * \param Builder          The \c DIBuilder.
  * \param ParentScope      The parent scope containing this module declaration.
  * \param Name             NameSpace name.
  * \param NameLen          The length of the C string passed to \c Name.
  * \param ExportSymbols    Whether or not the namespace exports symbols, e.g.

llvm/include/llvm/IR/DIBuilder.h

public:
     ///                      out into.
     /// \param Kind          The kind of debug information to generate.
     /// \param DWOId         The DWOId if this is a split skeleton compile unit.
     /// \param SplitDebugInlining    Whether to emit inline debug info.
     /// \param DebugInfoForProfiling Whether to emit extra debug info for
     ///                              profile collection.
     /// \param NameTableKind  Whether to emit .debug_gnu_pubnames,
     ///                      .debug_pubnames, or no pubnames at all.
+    /// \param SysRoot       The clang system root (value of -isysroot).
     DICompileUnit *
     createCompileUnit(unsigned Lang, DIFile *File, StringRef Producer,
                       bool isOptimized, StringRef Flags, unsigned RV,
                       StringRef SplitName = StringRef(),
                       DICompileUnit::DebugEmissionKind Kind =
                           DICompileUnit::DebugEmissionKind::FullDebug,
                       uint64_t DWOId = 0, bool SplitDebugInlining = true,
                       bool DebugInfoForProfiling = false,
                       DICompileUnit::DebugNameTableKind NameTableKind =
                           DICompileUnit::DebugNameTableKind::Default,
-                      bool RangesBaseAddress = false);
+                      bool RangesBaseAddress = false, StringRef SysRoot = {});
 
     /// Create a file descriptor to hold debugging information for a file.
     /// \param Filename  File name.
     /// \param Directory Directory.
     /// \param Checksum  Optional checksum kind (e.g. CSK_MD5, CSK_SHA1, etc.)
     ///                  and value.
     /// \param Source    Optional source text.
     DIFile *
public:
     /// This creates new descriptor for a module with the specified
     /// parent scope.
     /// \param Scope       Parent scope
     /// \param Name        Name of this module
     /// \param ConfigurationMacros
     ///                    A space-separated shell-quoted list of -D macro
     ///                    definitions as they would appear on a command line.
     /// \param IncludePath The path to the module map file.
-    /// \param SysRoot     The clang system root (value of -isysroot).
     DIModule *createModule(DIScope *Scope, StringRef Name,
                            StringRef ConfigurationMacros,
-                           StringRef IncludePath,
-                           StringRef SysRoot);
+                           StringRef IncludePath);
 
     /// This creates a descriptor for a lexical block with a new file
     /// attached. This merely extends the existing
     /// lexical block as it crosses a file.
     /// \param Scope       Lexical block.
     /// \param File        Source file.
     /// \param Discriminator DWARF path discriminator value.
     DILexicalBlockFile *createLexicalBlockFile(DIScope *Scope, DIFile *File,

llvm/include/llvm/IR/DebugInfoMetadata.h

private:
   getImpl(LLVMContext &Context, unsigned SourceLanguage, DIFile *File,
           StringRef Producer, bool IsOptimized, StringRef Flags,
           unsigned RuntimeVersion, StringRef SplitDebugFilename,
           unsigned EmissionKind, DICompositeTypeArray EnumTypes,
           DIScopeArray RetainedTypes,
           DIGlobalVariableExpressionArray GlobalVariables,
           DIImportedEntityArray ImportedEntities, DIMacroNodeArray Macros,
           uint64_t DWOId, bool SplitDebugInlining, bool DebugInfoForProfiling,
-          unsigned NameTableKind, bool RangesBaseAddress, StorageType Storage,
-          bool ShouldCreate = true) {
-    return getImpl(Context, SourceLanguage, File,
-                   getCanonicalMDString(Context, Producer), IsOptimized,
-                   getCanonicalMDString(Context, Flags), RuntimeVersion,
-                   getCanonicalMDString(Context, SplitDebugFilename),
-                   EmissionKind, EnumTypes.get(), RetainedTypes.get(),
-                   GlobalVariables.get(), ImportedEntities.get(), Macros.get(),
-                   DWOId, SplitDebugInlining, DebugInfoForProfiling,
-                   NameTableKind, RangesBaseAddress, Storage, ShouldCreate);
+          unsigned NameTableKind, bool RangesBaseAddress, StringRef SysRoot,
+          StorageType Storage, bool ShouldCreate = true) {
+    return getImpl(
+        Context, SourceLanguage, File, getCanonicalMDString(Context, Producer),
+        IsOptimized, getCanonicalMDString(Context, Flags), RuntimeVersion,
+        getCanonicalMDString(Context, SplitDebugFilename), EmissionKind,
+        EnumTypes.get(), RetainedTypes.get(), GlobalVariables.get(),
+        ImportedEntities.get(), Macros.get(), DWOId, SplitDebugInlining,
+        DebugInfoForProfiling, NameTableKind, RangesBaseAddress,
+        getCanonicalMDString(Context, SysRoot), Storage, ShouldCreate);
   }
   static DICompileUnit *
   getImpl(LLVMContext &Context, unsigned SourceLanguage, Metadata *File,
           MDString *Producer, bool IsOptimized, MDString *Flags,
           unsigned RuntimeVersion, MDString *SplitDebugFilename,
           unsigned EmissionKind, Metadata *EnumTypes, Metadata *RetainedTypes,
           Metadata *GlobalVariables, Metadata *ImportedEntities,
           Metadata *Macros, uint64_t DWOId, bool SplitDebugInlining,
           bool DebugInfoForProfiling, unsigned NameTableKind,
-          bool RangesBaseAddress, StorageType Storage, bool ShouldCreate = true);
+          bool RangesBaseAddress, MDString *SysRoot, StorageType Storage,
+          bool ShouldCreate = true);
 
   TempDICompileUnit cloneImpl() const {
     return getTemporary(
         getContext(), getSourceLanguage(), getFile(), getProducer(),
         isOptimized(), getFlags(), getRuntimeVersion(), getSplitDebugFilename(),
         getEmissionKind(), getEnumTypes(), getRetainedTypes(),
         getGlobalVariables(), getImportedEntities(), getMacros(), DWOId,
         getSplitDebugInlining(), getDebugInfoForProfiling(), getNameTableKind(),
-        getRangesBaseAddress());
+        getRangesBaseAddress(), getSysRoot());
   }
 
 public:
   static void get() = delete;
   static void getIfExists() = delete;
 
   DEFINE_MDNODE_GET_DISTINCT_TEMPORARY(
       DICompileUnit,
       (unsigned SourceLanguage, DIFile *File, StringRef Producer,
        bool IsOptimized, StringRef Flags, unsigned RuntimeVersion,
        StringRef SplitDebugFilename, DebugEmissionKind EmissionKind,
        DICompositeTypeArray EnumTypes, DIScopeArray RetainedTypes,
        DIGlobalVariableExpressionArray GlobalVariables,
        DIImportedEntityArray ImportedEntities, DIMacroNodeArray Macros,
        uint64_t DWOId, bool SplitDebugInlining, bool DebugInfoForProfiling,
-       DebugNameTableKind NameTableKind, bool RangesBaseAddress),
+       DebugNameTableKind NameTableKind, bool RangesBaseAddress,
+       StringRef SysRoot),
       (SourceLanguage, File, Producer, IsOptimized, Flags, RuntimeVersion,
        SplitDebugFilename, EmissionKind, EnumTypes, RetainedTypes,
        GlobalVariables, ImportedEntities, Macros, DWOId, SplitDebugInlining,
-       DebugInfoForProfiling, (unsigned)NameTableKind, RangesBaseAddress))
+       DebugInfoForProfiling, (unsigned)NameTableKind, RangesBaseAddress,
+       SysRoot))
   DEFINE_MDNODE_GET_DISTINCT_TEMPORARY(
       DICompileUnit,
       (unsigned SourceLanguage, Metadata *File, MDString *Producer,
        bool IsOptimized, MDString *Flags, unsigned RuntimeVersion,
        MDString *SplitDebugFilename, unsigned EmissionKind, Metadata *EnumTypes,
        Metadata *RetainedTypes, Metadata *GlobalVariables,
        Metadata *ImportedEntities, Metadata *Macros, uint64_t DWOId,
        bool SplitDebugInlining, bool DebugInfoForProfiling,
-       unsigned NameTableKind, bool RangesBaseAddress),
+       unsigned NameTableKind, bool RangesBaseAddress, MDString *SysRoot),
       (SourceLanguage, File, Producer, IsOptimized, Flags, RuntimeVersion,
        SplitDebugFilename, EmissionKind, EnumTypes, RetainedTypes,
        GlobalVariables, ImportedEntities, Macros, DWOId, SplitDebugInlining,
-       DebugInfoForProfiling, NameTableKind, RangesBaseAddress))
+       DebugInfoForProfiling, NameTableKind, RangesBaseAddress, SysRoot))
 
   TempDICompileUnit clone() const { return cloneImpl(); }
 
   unsigned getSourceLanguage() const { return SourceLanguage; }
   bool isOptimized() const { return IsOptimized; }
   unsigned getRuntimeVersion() const { return RuntimeVersion; }
   DebugEmissionKind getEmissionKind() const {
     return (DebugEmissionKind)EmissionKind;
   }
   bool isDebugDirectivesOnly() const {
     return EmissionKind == DebugDirectivesOnly;
   }
   bool getDebugInfoForProfiling() const { return DebugInfoForProfiling; }
   DebugNameTableKind getNameTableKind() const {
     return (DebugNameTableKind)NameTableKind;
   }
-  bool getRangesBaseAddress() const {
-    return RangesBaseAddress; }
-  StringRef getProducer() const {
-    return getStringOperand(1); }
-  StringRef getFlags() const {
-    return getStringOperand(2); }
-  StringRef getSplitDebugFilename() const {
-    return getStringOperand(3); }
+  bool getRangesBaseAddress() const { return RangesBaseAddress; }
+  StringRef getProducer() const { return getStringOperand(1); }
+  StringRef getFlags() const { return getStringOperand(2); }
+  StringRef getSplitDebugFilename() const { return getStringOperand(3); }
   DICompositeTypeArray getEnumTypes() const {
     return cast_or_null<MDTuple>(getRawEnumTypes());
   }
   DIScopeArray getRetainedTypes() const {
     return cast_or_null<MDTuple>(getRawRetainedTypes());
   }
   DIGlobalVariableExpressionArray getGlobalVariables() const {
     return cast_or_null<MDTuple>(getRawGlobalVariables());
   }
   DIImportedEntityArray getImportedEntities() const {
     return cast_or_null<MDTuple>(getRawImportedEntities());
   }
   DIMacroNodeArray getMacros() const {
     return cast_or_null<MDTuple>(getRawMacros());
   }
   uint64_t getDWOId() const { return DWOId; }
   void setDWOId(uint64_t DwoId) { DWOId = DwoId; }
   bool getSplitDebugInlining() const { return SplitDebugInlining; }
   void setSplitDebugInlining(bool SplitDebugInlining) {
     this->SplitDebugInlining = SplitDebugInlining;
   }
+  StringRef getSysRoot() const { return getStringOperand(9); }
 
   MDString *getRawProducer() const { return getOperandAs<MDString>(1); }
   MDString *getRawFlags() const { return getOperandAs<MDString>(2); }
   MDString *getRawSplitDebugFilename() const {
     return getOperandAs<MDString>(3);
   }
   Metadata *getRawEnumTypes() const { return getOperand(4); }
   Metadata *getRawRetainedTypes() const { return getOperand(5); }
   Metadata *getRawGlobalVariables() const { return getOperand(6); }
   Metadata *getRawImportedEntities() const { return getOperand(7); }
   Metadata *getRawMacros() const { return getOperand(8); }
+  MDString *getRawSysRoot() const { return getOperandAs<MDString>(9); }
 
   /// Replace arrays.
   ///
   /// If this \a isUniqued() and not \a isResolved(), it will be RAUW'ed and
   /// deleted on a uniquing collision.  In practice, uniquing collisions on \a
   /// DICompileUnit should be fairly rare.
   /// @{
   void replaceEnumTypes(DICompositeTypeArray N) {

 class DIModule : public DIScope {
   friend class LLVMContextImpl;
   friend class MDNode;
 
   DIModule(LLVMContext &Context, StorageType Storage, ArrayRef<Metadata *> Ops)
       : DIScope(Context, DIModuleKind, Storage, dwarf::DW_TAG_module, Ops) {}
   ~DIModule() = default;
 
-  static DIModule *getImpl(LLVMContext &Context, DIScope *Scope,
-                           StringRef Name, StringRef ConfigurationMacros,
-                           StringRef IncludePath, StringRef SysRoot,
+  static DIModule *getImpl(LLVMContext &Context, DIScope *Scope, StringRef Name,
+                           StringRef ConfigurationMacros, StringRef IncludePath,
                            StorageType Storage, bool ShouldCreate = true) {
     return getImpl(Context, Scope, getCanonicalMDString(Context, Name),
                    getCanonicalMDString(Context, ConfigurationMacros),
                    getCanonicalMDString(Context, IncludePath),
-                   getCanonicalMDString(Context, SysRoot),
                    Storage, ShouldCreate);
   }
   static DIModule *getImpl(LLVMContext &Context, Metadata *Scope,
                            MDString *Name, MDString *ConfigurationMacros,
-                           MDString *IncludePath, MDString *SysRoot,
-                           StorageType Storage, bool ShouldCreate = true);
+                           MDString *IncludePath, StorageType Storage,
+                           bool ShouldCreate = true);
 
   TempDIModule cloneImpl() const {
     return getTemporary(getContext(), getScope(), getName(),
-                        getConfigurationMacros(), getIncludePath(),
-                        getSysRoot());
+                        getConfigurationMacros(), getIncludePath());
   }
 
 public:
-  DEFINE_MDNODE_GET(DIModule, (DIScope *Scope, StringRef Name,
-                               StringRef ConfigurationMacros, StringRef IncludePath,
-                               StringRef SysRoot),
-                    (Scope, Name, ConfigurationMacros, IncludePath, SysRoot))
+  DEFINE_MDNODE_GET(DIModule,
+                    (DIScope * Scope, StringRef Name,
+                     StringRef ConfigurationMacros, StringRef IncludePath),
+                    (Scope, Name, ConfigurationMacros, IncludePath))
   DEFINE_MDNODE_GET(DIModule,
                     (Metadata *Scope, MDString *Name, MDString *ConfigurationMacros,
-                     MDString *IncludePath, MDString *SysRoot),
-                    (Scope, Name, ConfigurationMacros, IncludePath, SysRoot))
+                     MDString *IncludePath),
+                    (Scope, Name, ConfigurationMacros, IncludePath))
 
   TempDIModule clone() const { return cloneImpl(); }
 
   DIScope *getScope() const { return cast_or_null<DIScope>(getRawScope()); }
   StringRef getName() const { return getStringOperand(1); }
   StringRef getConfigurationMacros() const { return getStringOperand(2); }
   StringRef getIncludePath() const { return getStringOperand(3); }
-  StringRef getSysRoot() const { return getStringOperand(4); }
 
   Metadata *getRawScope() const { return getOperand(0); }
   MDString *getRawName() const { return getOperandAs<MDString>(1); }
   MDString *getRawConfigurationMacros() const { return getOperandAs<MDString>(2); }
   MDString *getRawIncludePath() const { return getOperandAs<MDString>(3); }
-  MDString *getRawSysRoot() const { return getOperandAs<MDString>(4); }
 
   static bool classof(const Metadata *MD) {
     return MD->getMetadataID() == DIModuleKind;
   }
 };
 
 /// Base class for template parameters.
 class DITemplateParameter : public DINode {

llvm/lib/AsmParser/LLParser.cpp

#undef VISIT_MD_FIELDS
   return false;
 }
 
 /// ParseDICompileUnit:
 ///   ::= !DICompileUnit(language: DW_LANG_C99, file: !0, producer: "clang",
 ///                      isOptimized: true, flags: "-O2", runtimeVersion: 1,
 ///                      splitDebugFilename: "abc.debug",
 ///                      emissionKind: FullDebug, enums: !1, retainedTypes: !2,
-///                      globals: !4, imports: !5, macros: !6, dwoId: 0x0abcd)
+///                      globals: !4, imports: !5, macros: !6, dwoId: 0x0abcd,
+///                      sysroot: "/")
 bool LLParser::ParseDICompileUnit(MDNode *&Result, bool IsDistinct) {
   if (!IsDistinct)
     return Lex.Error("missing 'distinct', required for !DICompileUnit");
 
 #define VISIT_MD_FIELDS(OPTIONAL, REQUIRED)                                    \
   REQUIRED(language, DwarfLangField, );                                        \
   REQUIRED(file, MDField, (/* AllowNull */ false));                            \
   OPTIONAL(producer, MDStringField, );                                         \
   OPTIONAL(isOptimized, MDBoolField, );                                        \
   OPTIONAL(flags, MDStringField, );                                            \
   OPTIONAL(runtimeVersion, MDUnsignedField, (0, UINT32_MAX));                  \
   OPTIONAL(splitDebugFilename, MDStringField, );                               \
   OPTIONAL(emissionKind, EmissionKindField, );                                 \
   OPTIONAL(enums, MDField, );                                                  \
   OPTIONAL(retainedTypes, MDField, );                                          \
   OPTIONAL(globals, MDField, );                                                \
   OPTIONAL(imports, MDField, );                                                \
   OPTIONAL(macros, MDField, );                                                 \
   OPTIONAL(dwoId, MDUnsignedField, );                                          \
   OPTIONAL(splitDebugInlining, MDBoolField, = true);                           \
   OPTIONAL(debugInfoForProfiling, MDBoolField, = false);                       \
   OPTIONAL(nameTableKind, NameTableKindField, );                               \
-  OPTIONAL(debugBaseAddress, MDBoolField, = false);
+  OPTIONAL(debugBaseAddress, MDBoolField, = false);                            \
+  OPTIONAL(sysroot, MDStringField, );
   PARSE_MD_FIELDS();
 #undef VISIT_MD_FIELDS
 
   Result = DICompileUnit::getDistinct(
       Context, language.Val, file.Val, producer.Val, isOptimized.Val, flags.Val,
       runtimeVersion.Val, splitDebugFilename.Val, emissionKind.Val, enums.Val,
       retainedTypes.Val, globals.Val, imports.Val, macros.Val, dwoId.Val,
       splitDebugInlining.Val, debugInfoForProfiling.Val, nameTableKind.Val,
-      debugBaseAddress.Val);
+      debugBaseAddress.Val, sysroot.Val);
   return false;
 }
 
 /// ParseDISubprogram:
 ///   ::= !DISubprogram(scope: !0, name: "foo", linkageName: "_Zfoo",
 ///                     file: !1, line: 7, type: !2, isLocal: false,
 ///                     isDefinition: true, scopeLine: 8, containingType: !3,
 ///                     virtuality: DW_VIRTUALTIY_pure_virtual,
#undef VISIT_MD_FIELDS
 
   Result = GET_OR_DISTINCT(DIMacroFile,
                            (Context, type.Val, line.Val, file.Val, nodes.Val));
   return false;
 }
 
 /// ParseDIModule:
 ///   ::= !DIModule(scope: !0, name: "SomeModule", configMacros: "-DNDEBUG",
-///                 includePath: "/usr/include", sysroot: "/")
+///                 includePath: "/usr/include")
 bool LLParser::ParseDIModule(MDNode *&Result, bool IsDistinct) {
 #define VISIT_MD_FIELDS(OPTIONAL, REQUIRED)                                    \
   REQUIRED(scope, MDField, );                                                  \
   REQUIRED(name, MDStringField, );                                             \
   OPTIONAL(configMacros, MDStringField, );                                     \
-  OPTIONAL(includePath, MDStringField, );                                      \
-  OPTIONAL(sysroot, MDStringField, );
+  OPTIONAL(includePath, MDStringField, );
   PARSE_MD_FIELDS();
 #undef VISIT_MD_FIELDS
 
   Result = GET_OR_DISTINCT(DIModule, (Context, scope.Val, name.Val,
-                           configMacros.Val, includePath.Val, sysroot.Val));
+                           configMacros.Val, includePath.Val));
   return false;
 }
 
 /// ParseDITemplateTypeParameter:
 ///   ::= !DITemplateTypeParameter(name: "Ty", type: !1)
 bool LLParser::ParseDITemplateTypeParameter(MDNode *&Result, bool IsDistinct) {
 #define VISIT_MD_FIELDS(OPTIONAL, REQUIRED)                                    \
   OPTIONAL(name, MDStringField, );                                             \

llvm/lib/Bitcode/Reader/MetadataLoader.cpp

case bitc::METADATA_SUBROUTINE_TYPE: {
     MetadataList.assignValue(
         GET_OR_DISTINCT(DISubroutineType, (Context, Flags, CC, Types)),
         NextMetadataNo);
     NextMetadataNo++;
     break;
   }
 
   case bitc::METADATA_MODULE: {
-    if (Record.size() != 6)
+    if (Record.size() < 5 || Record.size() > 6)
       return error("Invalid record");
 
     IsDistinct = Record[0];
     MetadataList.assignValue(
-        GET_OR_DISTINCT(DIModule,
-                        (Context, getMDOrNull(Record[1]),
-                         getMDString(Record[2]), getMDString(Record[3]),
-                         getMDString(Record[4]), getMDString(Record[5]))),
+        GET_OR_DISTINCT(
+            DIModule, (Context, getMDOrNull(Record[1]), getMDString(Record[2]),
+                       getMDString(Record[3]), getMDString(Record[4]))),
         NextMetadataNo);
     NextMetadataNo++;
     break;
   }
 
   case bitc::METADATA_FILE: {
     if (Record.size() != 3 && Record.size() != 5 && Record.size() != 6)
       return error("Invalid record");
MetadataList.assignValue(
             (Context, getMDString(Record[1]), getMDString(Record[2]), Checksum,
              Record.size() > 5 ? Optional<MDString *>(getMDString(Record[5]))
                                : None)),
         NextMetadataNo);
     NextMetadataNo++;
     break;
   }
   case bitc::METADATA_COMPILE_UNIT: {
-    if (Record.size() < 14 || Record.size() > 19)
+    if (Record.size() < 14 || Record.size() > 21)
       return error("Invalid record");
 
     // Ignore Record[0], which indicates whether this compile unit is
     // distinct.  It's always distinct.
     IsDistinct = true;
     auto *CU = DICompileUnit::getDistinct(
         Context, Record[1], getMDOrNull(Record[2]), getMDString(Record[3]),
         Record[4], getMDString(Record[5]), Record[6], getMDString(Record[7]),
         Record[8], getMDOrNull(Record[9]), getMDOrNull(Record[10]),
         getMDOrNull(Record[12]), getMDOrNull(Record[13]),
         Record.size() <= 15 ? nullptr : getMDOrNull(Record[15]),
         Record.size() <= 14 ? 0 : Record[14],
         Record.size() <= 16 ? true : Record[16],
         Record.size() <= 17 ? false : Record[17],
         Record.size() <= 18 ? 0 : Record[18],
-        Record.size() <= 19 ? 0 : Record[19]);
+        false, // FIXME: https://reviews.llvm.org/rGc51b45e32ef7f35c11891f60871aa9c2c04cd991
+               // Record.size() <= 19 ? 0 : Record[19],
+        Record.size() <= 20 ? nullptr : getMDString(Record[20]));
 
     MetadataList.assignValue(CU, NextMetadataNo);
     NextMetadataNo++;
 
     // Move the Upgrade the list of subprograms.
     if (Metadata *SPs = getMDOrNullWithoutPlaceholders(Record[11]))
       CUSubprograms.push_back({CU, SPs});
     break;

llvm/lib/Bitcode/Writer/BitcodeWriter.cpp

void ModuleBitcodeWriter::writeDICompileUnit(const DICompileUnit *N,
   Record.push_back(VE.getMetadataOrNullID(N->getRetainedTypes().get()));
   Record.push_back(/* subprograms */ 0);
   Record.push_back(VE.getMetadataOrNullID(N->getGlobalVariables().get()));
   Record.push_back(VE.getMetadataOrNullID(N->getImportedEntities().get()));
   Record.push_back(N->getDWOId());
   Record.push_back(VE.getMetadataOrNullID(N->getMacros().get()));
   Record.push_back(N->getSplitDebugInlining());
   Record.push_back(N->getDebugInfoForProfiling());
   Record.push_back((unsigned)N->getNameTableKind());
+  Record.push_back(N->getRangesBaseAddress());
+  Record.push_back(VE.getMetadataOrNullID(N->getRawSysRoot()));
 
   Stream.EmitRecord(bitc::METADATA_COMPILE_UNIT, Record, Abbrev);
   Record.clear();
 }
 
 void ModuleBitcodeWriter::writeDISubprogram(const DISubprogram *N,
                                             SmallVectorImpl<uint64_t> &Record,
                                             unsigned Abbrev) {

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

if (!Flags.empty() && !useAppleExtensionAttributes()) {
     std::string ProducerWithFlags = Producer.str() + " " + Flags.str();
     NewCU.addString(Die, dwarf::DW_AT_producer, ProducerWithFlags);
   } else
     NewCU.addString(Die, dwarf::DW_AT_producer, Producer);
 
   NewCU.addUInt(Die, dwarf::DW_AT_language, dwarf::DW_FORM_data2,
                 DIUnit->getSourceLanguage());
   NewCU.addString(Die, dwarf::DW_AT_name, FN);
+  StringRef SysRoot = DIUnit->getSysRoot();
+  if (!SysRoot.empty())
+    NewCU.addString(Die, dwarf::DW_AT_LLVM_sysroot, SysRoot);
 
   // Add DW_str_offsets_base to the unit DIE, except for split units.
   if (useSegmentedStringOffsetsTable() && !useSplitDwarf())
     NewCU.addStringOffsetsStart();
 
   if (!useSplitDwarf()) {
     NewCU.initStmtList();
 
     // If we're using split dwarf the compilation dir is going to be in the
     // skeleton CU and so we don't need to duplicate it here.
     if (!CompilationDir.empty())
       NewCU.addString(Die, dwarf::DW_AT_comp_dir, CompilationDir);
-
     addGnuPubAttributes(NewCU, Die);
   }
 
   if (useAppleExtensionAttributes()) {
     if (DIUnit->isOptimized())
       NewCU.addFlag(Die, dwarf::DW_AT_APPLE_optimized);
 
     StringRef Flags = DIUnit->getFlags();

 // Create new DwarfCompileUnit for the given metadata node with tag
 // DW_TAG_compile_unit.
 DwarfCompileUnit &
 DwarfDebug::getOrCreateDwarfCompileUnit(const DICompileUnit *DIUnit) {
   if (auto *CU = CUMap.lookup(DIUnit))
     return *CU;
 
   CompilationDir = DIUnit->getDirectory();
 
   auto OwnedUnit = std::make_unique<DwarfCompileUnit>(
       InfoHolder.getUnits().size(), DIUnit, Asm, this, &InfoHolder);
   DwarfCompileUnit &NewCU = *OwnedUnit;
   InfoHolder.addUnit(std::move(OwnedUnit));
 
   for (auto *IE : DIUnit->getImportedEntities())
     NewCU.addImportedEntity(IE);
 

 
 // DWARF5 Experimental Separate Dwarf emitters.
 
 void DwarfDebug::initSkeletonUnit(const DwarfUnit &U, DIE &Die,
                                   std::unique_ptr<DwarfCompileUnit> NewU) {
 
   if (!CompilationDir.empty())
     NewU->addString(Die, dwarf::DW_AT_comp_dir, CompilationDir);
-
   addGnuPubAttributes(*NewU, Die);
 
   SkeletonHolder.addUnit(std::move(NewU));
 }
 
 DwarfCompileUnit &DwarfDebug::constructSkeletonCU(const DwarfCompileUnit &CU) {
 
   auto OwnedUnit = std::make_unique<DwarfCompileUnit>(

llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp

if (!M->getName().empty()) {
     addString(MDie, dwarf::DW_AT_name, M->getName());
     addGlobalName(M->getName(), MDie, M->getScope());
   }
   if (!M->getConfigurationMacros().empty())
     addString(MDie, dwarf::DW_AT_LLVM_config_macros,
               M->getConfigurationMacros());
   if (!M->getIncludePath().empty())
     addString(MDie, dwarf::DW_AT_LLVM_include_path, M->getIncludePath());
-  if (!M->getSysRoot().empty())
-    addString(MDie, dwarf::DW_AT_LLVM_sysroot, M->getSysRoot());
 
   return &MDie;
 }
 
 DIE *DwarfUnit::getOrCreateSubprogramDIE(const DISubprogram *SP, bool Minimal) {
   // Construct the context before querying for the existence of the DIE in case
   // such construction creates the DIE (as is the case for member function
   // declarations).

llvm/lib/IR/AsmWriter.cpp

static void writeDICompileUnit(raw_ostream &Out, const DICompileUnit *N,
   Printer.printMetadata("imports", N->getRawImportedEntities());
   Printer.printMetadata("macros", N->getRawMacros());
   Printer.printInt("dwoId", N->getDWOId());
   Printer.printBool("splitDebugInlining", N->getSplitDebugInlining(), true);
   Printer.printBool("debugInfoForProfiling", N->getDebugInfoForProfiling(),
                     false);
   Printer.printNameTableKind("nameTableKind", N->getNameTableKind());
   Printer.printBool("rangesBaseAddress", N->getRangesBaseAddress(), false);
+  Printer.printString("sysroot", N->getSysRoot());
   Out << ")";
 }
 
 static void writeDISubprogram(raw_ostream &Out, const DISubprogram *N,
                               TypePrinting *TypePrinter, SlotTracker *Machine,
                               const Module *Context) {
   Out << "!DISubprogram(";
   MDFieldPrinter Printer(Out, TypePrinter, Machine, Context);
static void writeDIModule(raw_ostream &Out, const DIModule *N,
                           TypePrinting *TypePrinter, SlotTracker *Machine,
                           const Module *Context) {
   Out << "!DIModule(";
   MDFieldPrinter Printer(Out, TypePrinter, Machine, Context);
   Printer.printMetadata("scope", N->getRawScope(), /* ShouldSkipNull */ false);
   Printer.printString("name", N->getName());
   Printer.printString("configMacros", N->getConfigurationMacros());
   Printer.printString("includePath", N->getIncludePath());
-  Printer.printString("sysroot", N->getSysRoot());
   Out << ")";
 }
 
 
 static void writeDITemplateTypeParameter(raw_ostream &Out,
                                          const DITemplateTypeParameter *N,
                                          TypePrinting *TypePrinter,
                                          SlotTracker *Machine,

llvm/lib/IR/DIBuilder.cpp

static DIScope *getNonCompileUnitScope(DIScope *N) {
   return cast<DIScope>(N);
 }
 
 DICompileUnit *DIBuilder::createCompileUnit(
     unsigned Lang, DIFile *File, StringRef Producer, bool isOptimized,
     StringRef Flags, unsigned RunTimeVer, StringRef SplitName,
     DICompileUnit::DebugEmissionKind Kind, uint64_t DWOId,
     bool SplitDebugInlining, bool DebugInfoForProfiling,
-    DICompileUnit::DebugNameTableKind NameTableKind, bool RangesBaseAddress) {
+    DICompileUnit::DebugNameTableKind NameTableKind, bool RangesBaseAddress,
+    StringRef SysRoot) {
 
   assert(((Lang <= dwarf::DW_LANG_Fortran08 && Lang >= dwarf::DW_LANG_C89) ||
           (Lang <= dwarf::DW_LANG_hi_user && Lang >= dwarf::DW_LANG_lo_user)) &&
          "Invalid Language tag");
 
   assert(!CUNode && "Can only make one compile unit per DIBuilder instance");
   CUNode = DICompileUnit::getDistinct(
       VMContext, Lang, File, Producer, isOptimized, Flags, RunTimeVer,
       SplitName, Kind, nullptr, nullptr, nullptr, nullptr, nullptr, DWOId,
       SplitDebugInlining, DebugInfoForProfiling, NameTableKind,
-      RangesBaseAddress);
+      RangesBaseAddress, SysRoot);
 
   // Create a named metadata so that it is easier to find cu in a module.
   NamedMDNode *NMD = M.getOrInsertNamedMetadata("llvm.dbg.cu");
   NMD->addOperand(CUNode);
   trackIfUnresolved(CUNode);
   return CUNode;
 }
 
DINamespace *DIBuilder::createNameSpace(DIScope *Scope, StringRef Name,
   // DICompileUnit. This decision is an explicit tradeoff of link time versus
   // memory usage versus code simplicity and may get revisited in the future.
   return DINamespace::get(VMContext, getNonCompileUnitScope(Scope), Name,
                           ExportSymbols);
 }
 
 DIModule *DIBuilder::createModule(DIScope *Scope, StringRef Name,
                                   StringRef ConfigurationMacros,
-                                  StringRef IncludePath,
-                                  StringRef SysRoot) {
+                                  StringRef IncludePath) {
   return DIModule::get(VMContext, getNonCompileUnitScope(Scope), Name,
-                      ConfigurationMacros, IncludePath, SysRoot);
+                       ConfigurationMacros, IncludePath);
 }
 
 DILexicalBlockFile *DIBuilder::createLexicalBlockFile(DIScope *Scope,
                                                       DIFile *File,
                                                       unsigned Discriminator) {
   return DILexicalBlockFile::get(VMContext, Scope, File, Discriminator);
 }
 

llvm/lib/IR/DebugInfo.cpp

DICompileUnit *getReplacementCU(DICompileUnit *CU) {
     MDTuple *ImportedEntities = nullptr;
     return DICompileUnit::getDistinct(
         CU->getContext(), CU->getSourceLanguage(), File, CU->getProducer(),
         CU->isOptimized(), CU->getFlags(), CU->getRuntimeVersion(),
         CU->getSplitDebugFilename(), DICompileUnit::LineTablesOnly, EnumTypes,
         RetainedTypes, GlobalVariables, ImportedEntities, CU->getMacros(),
         CU->getDWOId(), CU->getSplitDebugInlining(),
         CU->getDebugInfoForProfiling(), CU->getNameTableKind(),
-        CU->getRangesBaseAddress());
+        CU->getRangesBaseAddress(), CU->getSysRoot());
   }
 
   DILocation *getReplacementMDLocation(DILocation *MLD) {
     auto *Scope = map(MLD->getScope());
     auto *InlinedAt = map(MLD->getInlinedAt());
     if (MLD->isDistinct())
       return DILocation::getDistinct(MLD->getContext(), MLD->getLine(),
                                      MLD->getColumn(), Scope, InlinedAt);

 }
 
 LLVMMetadataRef LLVMDIBuilderCreateCompileUnit(
     LLVMDIBuilderRef Builder, LLVMDWARFSourceLanguage Lang,
     LLVMMetadataRef FileRef, const char *Producer, size_t ProducerLen,
     LLVMBool isOptimized, const char *Flags, size_t FlagsLen,
     unsigned RuntimeVer, const char *SplitName, size_t SplitNameLen,
     LLVMDWARFEmissionKind Kind, unsigned DWOId, LLVMBool SplitDebugInlining,
-    LLVMBool DebugInfoForProfiling) {
+    LLVMBool DebugInfoForProfiling, const char *SysRoot, size_t SysRootLen) {
   auto File = unwrapDI<DIFile>(FileRef);
 
   return wrap(unwrap(Builder)->createCompileUnit(
-                 map_from_llvmDWARFsourcelanguage(Lang), File,
-                 StringRef(Producer, ProducerLen), isOptimized,
-                 StringRef(Flags, FlagsLen), RuntimeVer,
-                 StringRef(SplitName, SplitNameLen),
-                 static_cast<DICompileUnit::DebugEmissionKind>(Kind), DWOId,
-                 SplitDebugInlining, DebugInfoForProfiling));
+      StringRef(Producer, ProducerLen), isOptimized, StringRef(Flags, FlagsLen),
+      RuntimeVer, StringRef(SplitName, SplitNameLen),
+      SplitDebugInlining, DebugInfoForProfiling,
+      DICompileUnit::DebugNameTableKind::Default, false,
+      StringRef(SysRoot, SysRootLen)));
 }
 
 LLVMMetadataRef
 LLVMDIBuilderCreateFile(LLVMDIBuilderRef Builder, const char *Filename,
                         size_t FilenameLen, const char *Directory,
                         size_t DirectoryLen) {
   return wrap(unwrap(Builder)->createFile(StringRef(Filename, FilenameLen),
                                           StringRef(Directory, DirectoryLen)));
 }
 
 LLVMMetadataRef
 LLVMDIBuilderCreateModule(LLVMDIBuilderRef Builder, LLVMMetadataRef ParentScope,
                           const char *Name, size_t NameLen,
                           const char *ConfigMacros, size_t ConfigMacrosLen,
-                          const char *IncludePath, size_t IncludePathLen,
-                          const char *SysRoot, size_t SysRootLen) {
+                          const char *IncludePath, size_t IncludePathLen) {
   return wrap(unwrap(Builder)->createModule(
       unwrapDI<DIScope>(ParentScope), StringRef(Name, NameLen),
       StringRef(ConfigMacros, ConfigMacrosLen),
-      StringRef(IncludePath, IncludePathLen),
-      StringRef(SysRoot, SysRootLen)));
+      StringRef(IncludePath, IncludePathLen)));
 }
 
 LLVMMetadataRef LLVMDIBuilderCreateNameSpace(LLVMDIBuilderRef Builder,
                                              LLVMMetadataRef ParentScope,
                                              const char *Name, size_t NameLen,
                                              LLVMBool ExportSymbols) {
   return wrap(unwrap(Builder)->createNameSpace(
       unwrapDI<DIScope>(ParentScope), StringRef(Name, NameLen), ExportSymbols));

llvm/lib/IR/DebugInfoMetadata.cpp

 
 DICompileUnit *DICompileUnit::getImpl(
     LLVMContext &Context, unsigned SourceLanguage, Metadata *File,
     MDString *Producer, bool IsOptimized, MDString *Flags,
     unsigned RuntimeVersion, MDString *SplitDebugFilename,
     unsigned EmissionKind, Metadata *EnumTypes, Metadata *RetainedTypes,
     Metadata *GlobalVariables, Metadata *ImportedEntities, Metadata *Macros,
     uint64_t DWOId, bool SplitDebugInlining, bool DebugInfoForProfiling,
-    unsigned NameTableKind, bool RangesBaseAddress, StorageType Storage,
-    bool ShouldCreate) {
+    unsigned NameTableKind, bool RangesBaseAddress, MDString *SysRoot,
+    StorageType Storage, bool ShouldCreate) {
   assert(Storage != Uniqued && "Cannot unique DICompileUnit");
   assert(isCanonical(Producer) && "Expected canonical MDString");
   assert(isCanonical(Flags) && "Expected canonical MDString");
   assert(isCanonical(SplitDebugFilename) && "Expected canonical MDString");
 
   Metadata *Ops[] = {
       File,      Producer,      Flags,           SplitDebugFilename,
       EnumTypes, RetainedTypes, GlobalVariables, ImportedEntities,
-      Macros};
+      Macros,    SysRoot};
   return storeImpl(new (array_lengthof(Ops)) DICompileUnit(
                        Context, Storage, SourceLanguage, IsOptimized,
                        RuntimeVersion, EmissionKind, DWOId, SplitDebugInlining,
                        DebugInfoForProfiling, NameTableKind, RangesBaseAddress,
                        Ops),
                    Storage);
 }
 
DICommonBlock *DICommonBlock::getImpl(LLVMContext &Context, Metadata *Scope,
   DEFINE_GETIMPL_LOOKUP(DICommonBlock, (Scope, Decl, Name, File, LineNo));
   // The nullptr is for DIScope's File operand. This should be refactored.
   Metadata *Ops[] = {Scope, Decl, Name, File};
   DEFINE_GETIMPL_STORE(DICommonBlock, (LineNo), Ops);
 }
 
 DIModule *DIModule::getImpl(LLVMContext &Context, Metadata *Scope,
                             MDString *Name, MDString *ConfigurationMacros,
-                            MDString *IncludePath, MDString *SysRoot,
-                            StorageType Storage, bool ShouldCreate) {
+                            MDString *IncludePath, StorageType Storage,
+                            bool ShouldCreate) {
   assert(isCanonical(Name) && "Expected canonical MDString");
-  DEFINE_GETIMPL_LOOKUP(
-      DIModule, (Scope, Name, ConfigurationMacros, IncludePath, SysRoot));
-  Metadata *Ops[] = {Scope, Name, ConfigurationMacros, IncludePath, SysRoot};
+  DEFINE_GETIMPL_LOOKUP(DIModule,
+                        (Scope, Name, ConfigurationMacros, IncludePath));
+  Metadata *Ops[] = {Scope, Name, ConfigurationMacros, IncludePath};
   DEFINE_GETIMPL_STORE_NO_CONSTRUCTOR_ARGS(DIModule, Ops);
 }
 
 DITemplateTypeParameter *DITemplateTypeParameter::getImpl(LLVMContext &Context,
                                                           MDString *Name,
                                                           Metadata *Type,
                                                           StorageType Storage,
                                                           bool ShouldCreate) {

llvm/lib/IR/LLVMContextImpl.h

template <> struct MDNodeKeyImpl<DICommonBlock> {
   }
 };
 
 template <> struct MDNodeKeyImpl<DIModule> {
   Metadata *Scope;
   MDString *Name;
   MDString *ConfigurationMacros;
   MDString *IncludePath;
-  MDString *SysRoot;
 
   MDNodeKeyImpl(Metadata *Scope, MDString *Name, MDString *ConfigurationMacros,
-                MDString *IncludePath, MDString *SysRoot)
+                MDString *IncludePath)
       : Scope(Scope), Name(Name), ConfigurationMacros(ConfigurationMacros),
-        IncludePath(IncludePath), SysRoot(SysRoot) {}
+        IncludePath(IncludePath) {}
   MDNodeKeyImpl(const DIModule *N)
       : Scope(N->getRawScope()), Name(N->getRawName()),
         ConfigurationMacros(N->getRawConfigurationMacros()),
-        IncludePath(N->getRawIncludePath()), SysRoot(N->getRawSysRoot()) {}
+        IncludePath(N->getRawIncludePath()) {}
 
   bool isKeyOf(const DIModule *RHS) const {
     return Scope == RHS->getRawScope() && Name == RHS->getRawName() &&
            ConfigurationMacros == RHS->getRawConfigurationMacros() &&
-           IncludePath == RHS->getRawIncludePath() &&
-           SysRoot == RHS->getRawSysRoot();
+           IncludePath == RHS->getRawIncludePath();
   }
 
   unsigned getHashValue() const {
-    return hash_combine(Scope, Name,
-                        ConfigurationMacros, IncludePath, SysRoot);
+    return hash_combine(Scope, Name, ConfigurationMacros, IncludePath);
   }
 };
 
 template <> struct MDNodeKeyImpl<DITemplateTypeParameter> {
   MDString *Name;
   Metadata *Type;
 
   MDNodeKeyImpl(MDString *Name, Metadata *Type) : Name(Name), Type(Type) {}

llvm/test/Assembler/dicompileunit.ll

 !1 = !DIFile(filename: "path/to/file", directory: "/path/to/dir")
 !2 = distinct !{}
 !3 = distinct !{}
 !4 = distinct !{}
 !5 = distinct !{}
 !6 = distinct !{}
 !7 = distinct !{}
 
-; CHECK: !8 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang", isOptimized: true, flags: "-O2", runtimeVersion: 2, splitDebugFilename: "abc.debug", emissionKind: FullDebug, enums: !2, retainedTypes: !3, globals: !5, imports: !6, macros: !7, dwoId: 42)
+; CHECK: !8 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang", isOptimized: true, flags: "-O2", runtimeVersion: 2, splitDebugFilename: "abc.debug", emissionKind: FullDebug, enums: !2, retainedTypes: !3, globals: !5, imports: !6, macros: !7, dwoId: 42, sysroot: "/")
 !8 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang",
                              isOptimized: true, flags: "-O2", runtimeVersion: 2,
                              splitDebugFilename: "abc.debug",
                              emissionKind: FullDebug,
                              enums: !2, retainedTypes: !3,
-                             globals: !5, imports: !6, macros: !7, dwoId: 42, splitDebugInlining: true)
+                             globals: !5, imports: !6, macros: !7, dwoId: 42,
+                             splitDebugInlining: true, sysroot: "/")
 
 ; CHECK: !9 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, isOptimized: false, runtimeVersion: 0, emissionKind: NoDebug)
 !9 = distinct !DICompileUnit(language: 12, file: !1, producer: "",
                              isOptimized: false, flags: "", runtimeVersion: 0,
                              splitDebugFilename: "", emissionKind: NoDebug)
 
 ; CHECK: !10 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang", isOptimized: true, flags: "-O2", runtimeVersion: 2, splitDebugFilename: "abc.debug", emissionKind: LineTablesOnly, splitDebugInlining: false)
 !10 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang",
                              isOptimized: true, flags: "-O2", runtimeVersion: 2,
                              splitDebugFilename: "abc.debug",
                              emissionKind: LineTablesOnly, splitDebugInlining: false)
 
 !llvm.module.flags = !{!11}
 !11 = !{i32 2, !"Debug Info Version", i32 3}

llvm/test/Assembler/dimodule.ll

 ; RUN: llvm-as < %s | llvm-dis | llvm-as | llvm-dis | FileCheck %s
 ; RUN: verify-uselistorder %s
 
 ; CHECK: !named = !{!0, !1, !2, !1}
 !named = !{!0, !1, !2, !3}
 
 !0 = distinct !{}
 
 ; CHECK: !1 = !DIModule(scope: !0, name: "Module")
 !1 = !DIModule(scope: !0, name: "Module")
 
-; CHECK: !2 = !DIModule(scope: !0, name: "Module", configMacros: "-DNDEBUG", includePath: "/usr/include", sysroot: "/")
-!2 = !DIModule(scope: !0, name: "Module", configMacros: "-DNDEBUG", includePath: "/usr/include", sysroot: "/")
+; CHECK: !2 = !DIModule(scope: !0, name: "Module", configMacros: "-DNDEBUG", includePath: "/usr/include")
+!2 = !DIModule(scope: !0, name: "Module", configMacros: "-DNDEBUG", includePath: "/usr/include")
 
 !3 = !DIModule(scope: !0, name: "Module", configMacros: "")

llvm/test/Bindings/llvm-c/debug_info.ll

 ; CHECK-NEXT: declare void @llvm.dbg.value(metadata, metadata, metadata) #0
 
 ; CHECK:      attributes #0 = { nounwind readnone speculatable willreturn }
 
 ; CHECK:      !llvm.dbg.cu = !{!0}
 ; CHECK-NEXT: !FooType = !{!28}
 ; CHECK-NEXT: !EnumTest = !{!3}
 
-; CHECK:      !0 = distinct !DICompileUnit(language: DW_LANG_C, file: !1, producer: "llvm-c-test", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !11, imports: !19, macros: !23, splitDebugInlining: false)
+; CHECK:      !0 = distinct !DICompileUnit(language: DW_LANG_C, file: !1, producer: "llvm-c-test", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !11, imports: !19, macros: !23, splitDebugInlining: false, sysroot: "/")
 ; CHECK-NEXT: !1 = !DIFile(filename: "debuginfo.c", directory: ".")
 ; CHECK-NEXT: !2 = !{!3}
 ; CHECK-NEXT: !3 = !DICompositeType(tag: DW_TAG_enumeration_type, name: "EnumTest", scope: !4, file: !1, baseType: !6, size: 64, elements: !7)
 ; CHECK-NEXT: !4 = !DINamespace(name: "NameSpace", scope: !5)
 ; CHECK-NEXT: !5 = !DIModule(scope: null, name: "llvm-c-test", includePath: "/test/include/llvm-c-test.h")
 ; CHECK-NEXT: !6 = !DIBasicType(name: "Int64", size: 64)
 ; CHECK-NEXT: !7 = !{!8, !9, !10}
 ; CHECK-NEXT: !8 = !DIEnumerator(name: "Test_A", value: 0, isUnsigned: true)

llvm/test/CodeGen/X86/load-combine-dbg.ll

define i32 @zext_load(i32* %arg) !dbg !30 {
   %5 = zext i8 %3 to i32, !dbg !300
   ret i32 %5
 }
 !llvm.dbg.cu = !{!1}
 !llvm.module.flags = !{!0}
 
 !0 = !{i32 2, !"Debug Info Version", i32 3}
 !1 = distinct !DICompileUnit(language: DW_LANG_Swift, file: !3, isOptimized: false, emissionKind: FullDebug)
-!2 = !DIModule(scope: null, name: "test", includePath: "", sysroot: "/")
+!2 = !DIModule(scope: null, name: "test", includePath: "")
 !3 = !DIFile(filename: "main.swift", directory: "/")
 
 !30 = distinct !DISubprogram(name: "main", scope: !2, file: !3, line: 1, type: !31, isLocal: false, isDefinition: true, isOptimized: false, unit: !1)
 !31 = !DISubroutineType(types: !32)
 !32 = !{}
 
 !100 = !DILocation(line: 100, scope: !30)
 !200 = !DILocation(line: 200, scope: !30)
 !300 = !DILocation(line: 300, scope: !30)

llvm/test/DebugInfo/X86/DIModule.ll

 ; ModuleID = '/Volumes/Data/apple-internal/llvm/tools/clang/test/Modules/debug-info-moduleimport.m'
 ; RUN: llc %s -accel-tables=Dwarf -o %t -filetype=obj
 ; RUN: llvm-dwarfdump -debug-info %t | FileCheck %s
 ; RUN: llvm-dwarfdump -verify %t
-; CHECK: DW_TAG_module
+; CHECK: DW_TAG_compile_unit
+; CHECK-NOT: DW_TAG
+; CHECK:   DW_AT_LLVM_sysroot {{.*}}"/"
+; CHECK:   DW_TAG_module
 ; CHECK-NEXT: DW_AT_name {{.*}}"DebugModule"
 ; CHECK-NEXT: DW_AT_LLVM_config_macros {{.*}}"-DMODULES=0"
 ; CHECK-NEXT: DW_AT_LLVM_include_path {{.*}}"/llvm/tools/clang/test/Modules/Inputs"
-; CHECK-NEXT: DW_AT_LLVM_sysroot {{.*}}"/"
 
 target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-apple-macosx"
 
 !llvm.dbg.cu = !{!0}
 !llvm.module.flags = !{!6, !7}
 !llvm.ident = !{!8}
 
-!0 = distinct !DICompileUnit(language: DW_LANG_ObjC, file: !1, producer: "LLVM version 3.7.0", isOptimized: false, runtimeVersion: 2, emissionKind: FullDebug, enums: !2, retainedTypes: !2, globals: !2, imports: !3)
+!0 = distinct !DICompileUnit(language: DW_LANG_ObjC, file: !1, producer: "LLVM version 3.7.0", isOptimized: false, runtimeVersion: 2, emissionKind: FullDebug, enums: !2, retainedTypes: !2, globals: !2, imports: !3,  sysroot: "/")
 !1 = !DIFile(filename: "/llvm/tools/clang/test/Modules/<stdin>", directory: "/")
 !2 = !{}
 !3 = !{!4}
 !4 = !DIImportedEntity(tag: DW_TAG_imported_declaration, scope: !0, entity: !5, file: !1, line: 5)
-!5 = !DIModule(scope: null, name: "DebugModule", configMacros: "-DMODULES=0", includePath: "/llvm/tools/clang/test/Modules/Inputs", sysroot: "/")
+!5 = !DIModule(scope: null, name: "DebugModule", configMacros: "-DMODULES=0", includePath: "/llvm/tools/clang/test/Modules/Inputs")
 !6 = !{i32 2, !"Dwarf Version", i32 4}
 !7 = !{i32 2, !"Debug Info Version", i32 3}
 !8 = !{!"LLVM version 3.7.0"}

llvm/test/DebugInfo/X86/DIModuleContext.ll

 !0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
 !1 = !DIGlobalVariable(name: "s", scope: !2, file: !3, line: 2, type: !9, isLocal: false, isDefinition: true)
 !2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5, imports: !6)
 !3 = !DIFile(filename: "test.c", directory: "/")
 !4 = !{}
 !5 = !{!0}
 !6 = !{!7}
 !7 = !DIImportedEntity(tag: DW_TAG_imported_declaration, scope: !2, entity: !8, file: !3, line: 11)
-!8 = !DIModule(scope: null, name: "Module", includePath: ".", sysroot: "/")
+!8 = !DIModule(scope: null, name: "Module", includePath: ".")
 !9 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !10, size: 64, align: 64)
 !10 = !DICompositeType(tag: DW_TAG_structure_type, name: "s", scope: !8, file: !3, line: 1, flags: DIFlagFwdDecl)
 !11 = !{i32 2, !"Dwarf Version", i32 2}
 !12 = !{i32 2, !"Debug Info Version", i32 3}
 

llvm/test/DebugInfo/X86/clang-module.ll

 source_filename = "modules.m"
 target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-apple-macosx10.12.0"
 
 !llvm.dbg.cu = !{!0, !6}
 !llvm.module.flags = !{!15, !16}
 !llvm.linker.options = !{}
 
-!0 = distinct !DICompileUnit(language: DW_LANG_ObjC, file: !1, producer: "clang version 5.0.0 (trunk 308357) (llvm/trunk 308379)", emissionKind: FullDebug, imports: !3)
+!0 = distinct !DICompileUnit(language: DW_LANG_ObjC, file: !1, producer: "clang version 5.0.0 (trunk 308357) (llvm/trunk 308379)", emissionKind: FullDebug, imports: !3, sysroot: "/")
 !1 = !DIFile(filename: "modules.m", directory: "/")
 !3 = !{!4}
 !4 = !DIImportedEntity(tag: DW_TAG_imported_declaration, scope: !0, entity: !5, line: 122)
-!5 = !DIModule(scope: null, name: "Foo", includePath: ".", sysroot: "/")
+!5 = !DIModule(scope: null, name: "Foo", includePath: ".")
 !6 = distinct !DICompileUnit(language: DW_LANG_ObjC, file: !7, producer: "clang version 5.0.0 (trunk 308357) (llvm/trunk 308379)", isOptimized: true, runtimeVersion: 0, splitDebugFilename: "/Foo.pcm", emissionKind: FullDebug, dwoId: 1234)
 !7 = !DIFile(filename: "Foo", directory: ".")
 !15 = !{i32 2, !"Dwarf Version", i32 4}
 !16 = !{i32 2, !"Debug Info Version", i32 3}

llvm/test/DebugInfo/X86/split-dwarf-sysroot.ll

+; RUN: %llc_dwarf -split-dwarf-file=foo.dwo  %s -filetype=obj -o - | llvm-dwarfdump -debug-info - | FileCheck %s
+
+; DW_AT_LLVM_sysroot goes into the .dwo, not in the skeleton.
+
+; CHECK: DW_TAG_skeleton_unit
+; CHECK-NOT: DW_AT_LLVM_sysroot
+; CHECK: DW_TAG_compile_unit
+; CHECK-NOT: DW_TAG
+; CHECK: DW_AT_LLVM_sysroot ("/opt/clang-root")
+
+target triple = "x86_64-pc-linux"
+
+declare void @_Z2f1v()
+
+; Function Attrs: noinline norecurse uwtable
+define i32 @main() !dbg !9 {
+entry:
+  ret i32 0, !dbg !18
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!6, !7, !8}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C, file: !1, emissionKind: FullDebug, enums: !2, sysroot: "/opt/clang-root")
+!1 = !DIFile(filename: "a.c", directory: "/")
+!2 = !{}
+!6 = !{i32 2, !"Dwarf Version", i32 5}
+!7 = !{i32 2, !"Debug Info Version", i32 3}
+!8 = !{i32 1, !"wchar_size", i32 4}
+!9 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 2, type: !10, isLocal: false, isDefinition: true, scopeLine: 2, flags: DIFlagPrototyped, isOptimized: false, unit: !0, retainedNodes: !2)
+!10 = !DISubroutineType(types: !11)
+!11 = !{!12}
+!12 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!18 = !DILocation(line: 4, column: 1, scope: !9)

llvm/tools/llvm-c-test/debuginfo.c

 int llvm_test_dibuilder(void) {
   const char *Filename = "debuginfo.c";
   LLVMModuleRef M = LLVMModuleCreateWithName(Filename);
   LLVMDIBuilderRef DIB = LLVMCreateDIBuilder(M);
 
   LLVMMetadataRef File = LLVMDIBuilderCreateFile(DIB, Filename,
     strlen(Filename), ".", 1);
 
-  LLVMMetadataRef CompileUnit = LLVMDIBuilderCreateCompileUnit(DIB,
-    LLVMDWARFSourceLanguageC, File, "llvm-c-test", 11, 0, NULL, 0, 0,
-    NULL, 0, LLVMDWARFEmissionFull, 0, 0, 0);
+  LLVMMetadataRef CompileUnit = LLVMDIBuilderCreateCompileUnit(
+      DIB, LLVMDWARFSourceLanguageC, File, "llvm-c-test", 11, 0, NULL, 0, 0,
+      NULL, 0, LLVMDWARFEmissionFull, 0, 0, 0, "/", 1);
 
   LLVMMetadataRef Module =
     LLVMDIBuilderCreateModule(DIB, CompileUnit,
                               "llvm-c-test", 11,
                               "", 0,
-                              "/test/include/llvm-c-test.h", 27,
-                              "", 0);
+                              "/test/include/llvm-c-test.h", 27);
 
   LLVMMetadataRef OtherModule =
     LLVMDIBuilderCreateModule(DIB, CompileUnit,
                               "llvm-c-test-import", 18,
                               "", 0,
-                              "/test/include/llvm-c-test-import.h", 34,
-                              "", 0);
+                              "/test/include/llvm-c-test-import.h", 34);
   LLVMMetadataRef ImportedModule =
     LLVMDIBuilderCreateImportedModuleFromModule(DIB, Module, OtherModule,
                                                 File, 42);
   LLVMDIBuilderCreateImportedModuleFromAlias(DIB, Module, ImportedModule,
                                              File, 42);
 
   LLVMMetadataRef ClassTy = declare_objc_class(DIB, File);
   LLVMMetadataRef GlobalClassValueExpr =

llvm/unittests/IR/MetadataTest.cpp

protected:
   DIFile *getFile() {
     return DIFile::getDistinct(Context, "file.c", "/path/to/dir");
   }
   DICompileUnit *getUnit() {
     return DICompileUnit::getDistinct(
         Context, 1, getFile(), "clang", false, "-g", 2, "",
         DICompileUnit::FullDebug, getTuple(), getTuple(), getTuple(),
         getTuple(), getTuple(), 0, true, false,
-        DICompileUnit::DebugNameTableKind::Default, false);
+        DICompileUnit::DebugNameTableKind::Default, false, "/");
   }
   DIType *getBasicType(StringRef Name) {
     return DIBasicType::get(Context, dwarf::DW_TAG_unspecified_type, Name);
   }
   DIType *getDerivedType() {
     return DIDerivedType::getDistinct(
         Context, dwarf::DW_TAG_pointer_type, "", nullptr, 0, nullptr,
         getBasicType("basictype"), 1, 2, 0, None, DINode::FlagZero);
TEST_F(DICompileUnitTest, get) {
   StringRef SplitDebugFilename = "another/file";
   auto EmissionKind = DICompileUnit::FullDebug;
   MDTuple *EnumTypes = getTuple();
   MDTuple *RetainedTypes = getTuple();
   MDTuple *GlobalVariables = getTuple();
   MDTuple *ImportedEntities = getTuple();
   uint64_t DWOId = 0x10000000c0ffee;
   MDTuple *Macros = getTuple();
+  StringRef SysRoot = "/";
   auto *N = DICompileUnit::getDistinct(
       Context, SourceLanguage, File, Producer, IsOptimized, Flags,
       RuntimeVersion, SplitDebugFilename, EmissionKind, EnumTypes,
       RetainedTypes, GlobalVariables, ImportedEntities, Macros, DWOId, true,
-      false, DICompileUnit::DebugNameTableKind::Default, false);
+      false, DICompileUnit::DebugNameTableKind::Default, false, SysRoot);
 
   EXPECT_EQ(dwarf::DW_TAG_compile_unit, N->getTag());
   EXPECT_EQ(SourceLanguage, N->getSourceLanguage());
   EXPECT_EQ(File, N->getFile());
   EXPECT_EQ(Producer, N->getProducer());
   EXPECT_EQ(IsOptimized, N->isOptimized());
   EXPECT_EQ(Flags, N->getFlags());
   EXPECT_EQ(RuntimeVersion, N->getRuntimeVersion());
   EXPECT_EQ(SplitDebugFilename, N->getSplitDebugFilename());
   EXPECT_EQ(EmissionKind, N->getEmissionKind());
   EXPECT_EQ(EnumTypes, N->getEnumTypes().get());
   EXPECT_EQ(RetainedTypes, N->getRetainedTypes().get());
   EXPECT_EQ(GlobalVariables, N->getGlobalVariables().get());
   EXPECT_EQ(ImportedEntities, N->getImportedEntities().get());
   EXPECT_EQ(Macros, N->getMacros().get());
   EXPECT_EQ(DWOId, N->getDWOId());
+  EXPECT_EQ(SysRoot, N->getSysRoot());
 
   TempDICompileUnit Temp = N->clone();
   EXPECT_EQ(dwarf::DW_TAG_compile_unit, Temp->getTag());
   EXPECT_EQ(SourceLanguage, Temp->getSourceLanguage());
   EXPECT_EQ(File, Temp->getFile());
   EXPECT_EQ(Producer, Temp->getProducer());
   EXPECT_EQ(IsOptimized, Temp->isOptimized());
   EXPECT_EQ(Flags, Temp->getFlags());
   EXPECT_EQ(RuntimeVersion, Temp->getRuntimeVersion());
   EXPECT_EQ(SplitDebugFilename, Temp->getSplitDebugFilename());
   EXPECT_EQ(EmissionKind, Temp->getEmissionKind());
   EXPECT_EQ(EnumTypes, Temp->getEnumTypes().get());
   EXPECT_EQ(RetainedTypes, Temp->getRetainedTypes().get());
   EXPECT_EQ(GlobalVariables, Temp->getGlobalVariables().get());
   EXPECT_EQ(ImportedEntities, Temp->getImportedEntities().get());
   EXPECT_EQ(Macros, Temp->getMacros().get());
-  EXPECT_EQ(DWOId, Temp->getDWOId());
+  EXPECT_EQ(SysRoot, Temp->getSysRoot());
 
   auto *TempAddress = Temp.get();
   auto *Clone = MDNode::replaceWithPermanent(std::move(Temp));
   EXPECT_TRUE(Clone->isDistinct());
   EXPECT_EQ(TempAddress, Clone);
 }
 
 TEST_F(DICompileUnitTest, replaceArrays) {
   unsigned SourceLanguage = 1;
   DIFile *File = getFile();
   StringRef Producer = "some producer";
   bool IsOptimized = false;
   StringRef Flags = "flag after flag";
   unsigned RuntimeVersion = 2;
   StringRef SplitDebugFilename = "another/file";
   auto EmissionKind = DICompileUnit::FullDebug;
   MDTuple *EnumTypes = MDTuple::getDistinct(Context, None);
   MDTuple *RetainedTypes = MDTuple::getDistinct(Context, None);
   MDTuple *ImportedEntities = MDTuple::getDistinct(Context, None);
   uint64_t DWOId = 0xc0ffee;
+  StringRef SysRoot = "/";
   auto *N = DICompileUnit::getDistinct(
       Context, SourceLanguage, File, Producer, IsOptimized, Flags,
       RuntimeVersion, SplitDebugFilename, EmissionKind, EnumTypes,
       RetainedTypes, nullptr, ImportedEntities, nullptr, DWOId, true, false,
-      DICompileUnit::DebugNameTableKind::Default, false);
+      DICompileUnit::DebugNameTableKind::Default, false, SysRoot);
 
   auto *GlobalVariables = MDTuple::getDistinct(Context, None);
   EXPECT_EQ(nullptr, N->getGlobalVariables().get());
   N->replaceGlobalVariables(GlobalVariables);
   EXPECT_EQ(GlobalVariables, N->getGlobalVariables().get());
   N->replaceGlobalVariables(nullptr);
   EXPECT_EQ(nullptr, N->getGlobalVariables().get());
 

 
 typedef MetadataTest DIModuleTest;
 
 TEST_F(DIModuleTest, get) {
   DIScope *Scope = getFile();
   StringRef Name = "module";
   StringRef ConfigMacro = "-DNDEBUG";
   StringRef Includes = "-I.";
-  StringRef Sysroot = "/";
 
-  auto *N = DIModule::get(Context, Scope, Name, ConfigMacro, Includes, Sysroot);
+  auto *N = DIModule::get(Context, Scope, Name, ConfigMacro, Includes);
 
   EXPECT_EQ(dwarf::DW_TAG_module, N->getTag());
   EXPECT_EQ(Scope, N->getScope());
   EXPECT_EQ(Name, N->getName());
   EXPECT_EQ(ConfigMacro, N->getConfigurationMacros());
   EXPECT_EQ(Includes, N->getIncludePath());
-  EXPECT_EQ(Sysroot, N->getSysRoot());
-  EXPECT_EQ(N, DIModule::get(Context, Scope, Name,
-                             ConfigMacro, Includes, Sysroot));
-  EXPECT_NE(N, DIModule::get(Context, getFile(), Name,
-                             ConfigMacro, Includes, Sysroot));
-  EXPECT_NE(N, DIModule::get(Context, Scope, "other",
-                             ConfigMacro, Includes, Sysroot));
-  EXPECT_NE(N, DIModule::get(Context, Scope, Name,
-                             "other", Includes, Sysroot));
-  EXPECT_NE(N, DIModule::get(Context, Scope, Name,
-                             ConfigMacro, "other", Sysroot));
-  EXPECT_NE(N, DIModule::get(Context, Scope, Name,
-                             ConfigMacro, Includes, "other"));
+  EXPECT_EQ(N, DIModule::get(Context, Scope, Name, ConfigMacro, Includes));
+  EXPECT_NE(N, DIModule::get(Context, getFile(), Name, ConfigMacro, Includes));
+  EXPECT_NE(N, DIModule::get(Context, Scope, "other", ConfigMacro, Includes));
+  EXPECT_NE(N, DIModule::get(Context, Scope, Name, "other", Includes));
+  EXPECT_NE(N, DIModule::get(Context, Scope, Name, ConfigMacro, "other"));
 
   TempDIModule Temp = N->clone();
   EXPECT_EQ(N, MDNode::replaceWithUniqued(std::move(Temp)));
 }
 
 typedef MetadataTest DITemplateTypeParameterTest;
 
 TEST_F(DITemplateTypeParameterTest, get) {