Update clang, llvm, lld, lldb, compiler-rt and libc++ to 4.0.0 release:

MFC r309142 (by emaste):

Add WITH_LLD_AS_LD build knob

If set it installs LLD as /usr/bin/ld.  LLD (as of version 3.9) is not
capable of linking the world and kernel, but can self-host and link many
substantial applications. GNU ld continues to be used for the world and
kernel build, regardless of how this knob is set.

It is on by default for arm64, and off for all other CPU architectures.

Sponsored by:	The FreeBSD Foundation

MFC r310840:

Reapply 310775, now it also builds correctly if lldb is disabled:

Move llvm-objdump from CLANG_EXTRAS to installed by default

We currently install three tools from binutils 2.17.50: as, ld, and
objdump. Work is underway to migrate to a permissively-licensed
tool-chain, with one goal being the retirement of binutils 2.17.50.

LLVM's llvm-objdump is intended to be compatible with GNU objdump
although it is currently missing some options and may have formatting
differences. Enable it by default for testing and further investigation.
It may later be changed to install as /usr/bin/objdump, it becomes a
fully viable replacement.

Reviewed by:	emaste
Differential Revision:	https://reviews.freebsd.org/D8879

MFC r312855 (by emaste):

Rename LLD_AS_LD to LLD_IS_LD, for consistency with CLANG_IS_CC

Reported by:	Dan McGregor <dan.mcgregor usask.ca>

MFC r313559 | glebius | 2017-02-10 18:34:48 +0100 (Fri, 10 Feb 2017) | 5 lines

Don't check struct rtentry on FreeBSD, it is an internal kernel structure.
On other systems it may be API structure for SIOCADDRT/SIOCDELRT.

Reviewed by:	emaste, dim

MFC r314152 (by jkim):

Remove an assembler flag, which is redundant since r309124.  The upstream
took care of it by introducing a macro NO_EXEC_STACK_DIRECTIVE.

http://llvm.org/viewvc/llvm-project?rev=273500&view=rev

Reviewed by:	dim

MFC r314564:

Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
4.0.0 (branches/release_40 296509).  The release will follow soon.

Please note that from 3.5.0 onwards, clang, llvm and lldb require C++11
support to build; see UPDATING for more information.

Also note that as of 4.0.0, lld should be able to link the base system
on amd64 and aarch64.  See the WITH_LLD_IS_LLD setting in src.conf(5).
Though please be aware that this is work in progress.

Release notes for llvm, clang and lld will be available here:
<http://releases.llvm.org/4.0.0/docs/ReleaseNotes.html>
<http://releases.llvm.org/4.0.0/tools/clang/docs/ReleaseNotes.html>
<http://releases.llvm.org/4.0.0/tools/lld/docs/ReleaseNotes.html>

Thanks to Ed Maste, Jan Beich, Antoine Brodin and Eric Fiselier for
their help.

Relnotes:	yes
Exp-run:	antoine
PR:		215969, 216008

MFC r314708:

For now, revert r287232 from upstream llvm trunk (by Daniil Fukalov):

  [SCEV] limit recursion depth of CompareSCEVComplexity

  Summary:
  CompareSCEVComplexity goes too deep (50+ on a quite a big unrolled
  loop) and runs almost infinite time.

  Added cache of "equal" SCEV pairs to earlier cutoff of further
  estimation. Recursion depth limit was also introduced as a parameter.

  Reviewers: sanjoy

  Subscribers: mzolotukhin, tstellarAMD, llvm-commits

  Differential Revision: https://reviews.llvm.org/D26389

This commit is the cause of excessive compile times on skein_block.c
(and possibly other files) during kernel builds on amd64.

We never saw the problematic behavior described in this upstream commit,
so for now it is better to revert it.  An upstream bug has been filed
here: https://bugs.llvm.org/show_bug.cgi?id=32142

Reported by:	mjg

MFC r314795:

Reapply r287232 from upstream llvm trunk (by Daniil Fukalov):

  [SCEV] limit recursion depth of CompareSCEVComplexity

  Summary:
  CompareSCEVComplexity goes too deep (50+ on a quite a big unrolled
  loop) and runs almost infinite time.

  Added cache of "equal" SCEV pairs to earlier cutoff of further
  estimation. Recursion depth limit was also introduced as a parameter.

  Reviewers: sanjoy

  Subscribers: mzolotukhin, tstellarAMD, llvm-commits

  Differential Revision: https://reviews.llvm.org/D26389

Pull in r296992 from upstream llvm trunk (by Sanjoy Das):

  [SCEV] Decrease the recursion threshold for CompareValueComplexity

  Fixes PR32142.

  r287232 accidentally increased the recursion threshold for
  CompareValueComplexity from 2 to 32.  This change reverses that
  change by introducing a separate flag for CompareValueComplexity's
  threshold.

The latter revision fixes the excessive compile times for skein_block.c.

MFC r314907 | mmel | 2017-03-08 12:40:27 +0100 (Wed, 08 Mar 2017) | 7 lines

Unbreak ARMv6 world.

The new compiler_rt library imported with clang 4.0.0 have several fatal
issues (non-functional __udivsi3 for example) with ARM specific instrict
functions. As temporary workaround, until upstream solve these problems,
disable all thumb[1][2] related feature.

MFC r315016:

Update clang, llvm, lld, lldb, compiler-rt and libc++ to 4.0.0 release.
We were already very close to the last release candidate, so this is a
pretty minor update.

Relnotes:	yes

MFC r316005:

Revert r314907, and pull in r298713 from upstream compiler-rt trunk (by
Weiming Zhao):

  builtins: Select correct code fragments when compiling for Thumb1/Thum2/ARM ISA.

  Summary:
  Value of __ARM_ARCH_ISA_THUMB isn't based on the actual compilation
  mode (-mthumb, -marm), it reflect's capability of given CPU.

  Due to this:
   - use  __tbumb__ and __thumb2__ insteand of __ARM_ARCH_ISA_THUMB
   - use '.thumb' directive consistently  in all affected files
   - decorate all thumb functions using
     DEFINE_COMPILERRT_THUMB_FUNCTION()

  ---------
  Note: This patch doesn't fix broken Thumb1 variant of __udivsi3 !

  Reviewers: weimingz, rengolin, compnerd

  Subscribers: aemerson, dim

  Differential Revision: https://reviews.llvm.org/D30938

Discussed with:	mmel

1 files changed, 192 insertions, 69 deletions

diff --git a/contrib/llvm/tools/clang/lib/Parse/Parser.cpp b/contrib/llvm/tools/clang/lib/Parse/Parser.cpp
index f968f99..52e5194 100644
--- a/contrib/llvm/tools/clang/lib/Parse/Parser.cpp
+++ b/contrib/llvm/tools/clang/lib/Parse/Parser.cpp
@@ -20,7 +20,6 @@
 #include "clang/Sema/DeclSpec.h"
 #include "clang/Sema/ParsedTemplate.h"
 #include "clang/Sema/Scope.h"
-#include "llvm/Support/raw_ostream.h"
 using namespace clang;
 
 
@@ -78,7 +77,6 @@ Parser::Parser(Preprocessor &pp, Sema &actions, bool skipFunctionBodies)
   Tok.setKind(tok::eof);
   Actions.CurScope = nullptr;
   NumCachedScopes = 0;
-  ParenCount = BracketCount = BraceCount = 0;
   CurParsedObjCImpl = nullptr;
 
   // Add #pragma handlers. These are removed and destroyed in the
@@ -474,6 +472,7 @@ void Parser::Initialize() {
   Ident_final = nullptr;
   Ident_sealed = nullptr;
   Ident_override = nullptr;
+  Ident_GNU_final = nullptr;
 
   Ident_super = &PP.getIdentifierTable().get("super");
 
@@ -537,6 +536,36 @@ void Parser::LateTemplateParserCleanupCallback(void *P) {
   DestroyTemplateIdAnnotationsRAIIObj CleanupRAII(((Parser *)P)->TemplateIds);
 }
 
+bool Parser::ParseFirstTopLevelDecl(DeclGroupPtrTy &Result) {
+  // C++ Modules TS: module-declaration must be the first declaration in the
+  // file. (There can be no preceding preprocessor directives, but we expect
+  // the lexer to check that.)
+  if (Tok.is(tok::kw_module)) {
+    Result = ParseModuleDecl();
+    return false;
+  } else if (getLangOpts().getCompilingModule() ==
+             LangOptions::CMK_ModuleInterface) {
+    // FIXME: We avoid providing this diagnostic when generating an object file
+    // from an existing PCM file. This is not a good way to detect this
+    // condition; we should provide a mechanism to indicate whether we've
+    // already parsed a declaration in this translation unit and avoid calling
+    // ParseFirstTopLevelDecl in that case.
+    if (Actions.TUKind == TU_Module)
+      Diag(Tok, diag::err_expected_module_interface_decl);
+  }
+
+  // C11 6.9p1 says translation units must have at least one top-level
+  // declaration. C++ doesn't have this restriction. We also don't want to
+  // complain if we have a precompiled header, although technically if the PCH
+  // is empty we should still emit the (pedantic) diagnostic.
+  bool NoTopLevelDecls = ParseTopLevelDecl(Result);
+  if (NoTopLevelDecls && !Actions.getASTContext().getExternalSource() &&
+      !getLangOpts().CPlusPlus)
+    Diag(diag::ext_empty_translation_unit);
+
+  return NoTopLevelDecls;
+}
+
 /// ParseTopLevelDecl - Parse one top-level declaration, return whatever the
 /// action tells us to.  This returns true if the EOF was encountered.
 bool Parser::ParseTopLevelDecl(DeclGroupPtrTy &Result) {
@@ -553,6 +582,10 @@ bool Parser::ParseTopLevelDecl(DeclGroupPtrTy &Result) {
     HandlePragmaUnused();
     return false;
 
+  case tok::kw_import:
+    Result = ParseModuleImport(SourceLocation());
+    return false;
+
   case tok::annot_module_include:
     Actions.ActOnModuleInclude(Tok.getLocation(),
                                reinterpret_cast<Module *>(
@@ -590,7 +623,6 @@ bool Parser::ParseTopLevelDecl(DeclGroupPtrTy &Result) {
 
   ParsedAttributesWithRange attrs(AttrFactory);
   MaybeParseCXX11Attributes(attrs);
-  MaybeParseMicrosoftAttributes(attrs);
 
   Result = ParseExternalDeclaration(attrs);
   return false;
@@ -737,11 +769,17 @@ Parser::ParseExternalDeclaration(ParsedAttributesWithRange &attrs,
                                               : Sema::PCC_Namespace);
     cutOffParsing();
     return nullptr;
+  case tok::kw_export:
+    if (getLangOpts().ModulesTS) {
+      SingleDecl = ParseExportDeclaration();
+      break;
+    }
+    // This must be 'export template'. Parse it so we can diagnose our lack
+    // of support.
   case tok::kw_using:
   case tok::kw_namespace:
   case tok::kw_typedef:
   case tok::kw_template:
-  case tok::kw_export:    // As in 'export template'
   case tok::kw_static_assert:
   case tok::kw__Static_assert:
     // A function definition cannot start with any of these keywords.
@@ -802,6 +840,11 @@ Parser::ParseExternalDeclaration(ParsedAttributesWithRange &attrs,
     ParseMicrosoftIfExistsExternalDeclaration();
     return nullptr;
 
+  case tok::kw_module:
+    Diag(Tok, diag::err_unexpected_module_decl);
+    SkipUntil(tok::semi);
+    return nullptr;
+
   default:
   dont_know:
     // We can't tell whether this is a function-definition or declaration yet.
@@ -853,11 +896,10 @@ bool Parser::isStartOfFunctionDefinition(const ParsingDeclarator &Declarator) {
          Tok.is(tok::kw_try);          // X() try { ... }
 }
 
-/// ParseDeclarationOrFunctionDefinition - Parse either a function-definition or
-/// a declaration.  We can't tell which we have until we read up to the
-/// compound-statement in function-definition. TemplateParams, if
-/// non-NULL, provides the template parameters when we're parsing a
-/// C++ template-declaration.
+/// Parse either a function-definition or a declaration.  We can't tell which
+/// we have until we read up to the compound-statement in function-definition.
+/// TemplateParams, if non-NULL, provides the template parameters when we're
+/// parsing a C++ template-declaration.
 ///
 ///       function-definition: [C99 6.9.1]
 ///         decl-specs      declarator declaration-list[opt] compound-statement
@@ -873,6 +915,7 @@ Parser::DeclGroupPtrTy
 Parser::ParseDeclOrFunctionDefInternal(ParsedAttributesWithRange &attrs,
                                        ParsingDeclSpec &DS,
                                        AccessSpecifier AS) {
+  MaybeParseMicrosoftAttributes(DS.getAttributes());
   // Parse the common declaration-specifiers piece.
   ParseDeclarationSpecifiers(DS, ParsedTemplateInfo(), AS, DSC_top_level);
 
@@ -891,9 +934,11 @@ Parser::ParseDeclOrFunctionDefInternal(ParsedAttributesWithRange &attrs,
     Decl *TheDecl = Actions.ParsedFreeStandingDeclSpec(getCurScope(), AS_none,
                                                        DS, AnonRecord);
     DS.complete(TheDecl);
+    if (getLangOpts().OpenCL)
+      Actions.setCurrentOpenCLExtensionForDecl(TheDecl);
     if (AnonRecord) {
       Decl* decls[] = {AnonRecord, TheDecl};
-      return Actions.BuildDeclaratorGroup(decls, /*TypeMayContainAuto=*/false);
+      return Actions.BuildDeclaratorGroup(decls);
     }
     return Actions.ConvertDeclToDeclGroup(TheDecl);
   }
@@ -952,7 +997,7 @@ Parser::ParseDeclarationOrFunctionDefinition(ParsedAttributesWithRange &attrs,
     // parsing c constructs and re-enter objc container scope
     // afterwards.
     ObjCDeclContextSwitch ObjCDC(*this);
-      
+
     return ParseDeclOrFunctionDefInternal(attrs, PDS, AS);
   }
 }
@@ -1427,8 +1472,7 @@ Parser::TryAnnotateName(bool IsAddressOfOperand,
     return ANK_Error;
 
   if (Tok.isNot(tok::identifier) || SS.isInvalid()) {
-    if (TryAnnotateTypeOrScopeTokenAfterScopeSpec(EnteringContext, false, SS,
-                                                  !WasScopeAnnotation))
+    if (TryAnnotateTypeOrScopeTokenAfterScopeSpec(SS, !WasScopeAnnotation))
       return ANK_Error;
     return ANK_Unresolved;
   }
@@ -1441,8 +1485,7 @@ Parser::TryAnnotateName(bool IsAddressOfOperand,
   if (isTentativelyDeclared(Name)) {
     // Identifier has been tentatively declared, and thus cannot be resolved as
     // an expression. Fall back to annotating it as a type.
-    if (TryAnnotateTypeOrScopeTokenAfterScopeSpec(EnteringContext, false, SS,
-                                                  !WasScopeAnnotation))
+    if (TryAnnotateTypeOrScopeTokenAfterScopeSpec(SS, !WasScopeAnnotation))
       return ANK_Error;
     return Tok.is(tok::annot_typename) ? ANK_Success : ANK_TentativeDecl;
   }
@@ -1495,6 +1538,8 @@ Parser::TryAnnotateName(bool IsAddressOfOperand,
                                                    NewEndLoc);
       if (NewType.isUsable())
         Ty = NewType.get();
+      else if (Tok.is(tok::eof)) // Nothing to do here, bail out...
+        return ANK_Error;
     }
 
     Tok.setKind(tok::annot_typename);
@@ -1578,7 +1623,7 @@ bool Parser::TryKeywordIdentFallback(bool DisableKeyword) {
 ///
 /// Note that this routine emits an error if you call it with ::new or ::delete
 /// as the current tokens, so only call it in contexts where these are invalid.
-bool Parser::TryAnnotateTypeOrScopeToken(bool EnteringContext, bool NeedType) {
+bool Parser::TryAnnotateTypeOrScopeToken() {
   assert((Tok.is(tok::identifier) || Tok.is(tok::coloncolon) ||
           Tok.is(tok::kw_typename) || Tok.is(tok::annot_cxxscope) ||
           Tok.is(tok::kw_decltype) || Tok.is(tok::annot_template_id) ||
@@ -1595,7 +1640,7 @@ bool Parser::TryAnnotateTypeOrScopeToken(bool EnteringContext, bool NeedType) {
     if (getLangOpts().MSVCCompat && NextToken().is(tok::kw_typedef)) {
       Token TypedefToken;
       PP.Lex(TypedefToken);
-      bool Result = TryAnnotateTypeOrScopeToken(EnteringContext, NeedType);
+      bool Result = TryAnnotateTypeOrScopeToken();
       PP.EnterToken(Tok);
       Tok = TypedefToken;
       if (!Result)
@@ -1620,8 +1665,7 @@ bool Parser::TryAnnotateTypeOrScopeToken(bool EnteringContext, bool NeedType) {
           Tok.is(tok::annot_decltype)) {
         // Attempt to recover by skipping the invalid 'typename'
         if (Tok.is(tok::annot_decltype) ||
-            (!TryAnnotateTypeOrScopeToken(EnteringContext, NeedType) &&
-             Tok.isAnnotation())) {
+            (!TryAnnotateTypeOrScopeToken() && Tok.isAnnotation())) {
           unsigned DiagID = diag::err_expected_qualified_after_typename;
           // MS compatibility: MSVC permits using known types with typename.
           // e.g. "typedef typename T* pointer_type"
@@ -1681,33 +1725,24 @@ bool Parser::TryAnnotateTypeOrScopeToken(bool EnteringContext, bool NeedType) {
 
   CXXScopeSpec SS;
   if (getLangOpts().CPlusPlus)
-    if (ParseOptionalCXXScopeSpecifier(SS, nullptr, EnteringContext))
+    if (ParseOptionalCXXScopeSpecifier(SS, nullptr, /*EnteringContext*/false))
       return true;
 
-  return TryAnnotateTypeOrScopeTokenAfterScopeSpec(EnteringContext, NeedType,
-                                                   SS, !WasScopeAnnotation);
+  return TryAnnotateTypeOrScopeTokenAfterScopeSpec(SS, !WasScopeAnnotation);
 }
 
 /// \brief Try to annotate a type or scope token, having already parsed an
 /// optional scope specifier. \p IsNewScope should be \c true unless the scope
 /// specifier was extracted from an existing tok::annot_cxxscope annotation.
-bool Parser::TryAnnotateTypeOrScopeTokenAfterScopeSpec(bool EnteringContext,
-                                                       bool NeedType,
-                                                       CXXScopeSpec &SS,
+bool Parser::TryAnnotateTypeOrScopeTokenAfterScopeSpec(CXXScopeSpec &SS,
                                                        bool IsNewScope) {
   if (Tok.is(tok::identifier)) {
-    IdentifierInfo *CorrectedII = nullptr;
     // Determine whether the identifier is a type name.
     if (ParsedType Ty = Actions.getTypeName(
             *Tok.getIdentifierInfo(), Tok.getLocation(), getCurScope(), &SS,
             false, NextToken().is(tok::period), nullptr,
             /*IsCtorOrDtorName=*/false,
-            /*NonTrivialTypeSourceInfo*/ true,
-            NeedType ? &CorrectedII : nullptr)) {
-      // A FixIt was applied as a result of typo correction
-      if (CorrectedII)
-        Tok.setIdentifierInfo(CorrectedII);
-
+            /*NonTrivialTypeSourceInfo*/ true)) {
       SourceLocation BeginLoc = Tok.getLocation();
       if (SS.isNotEmpty()) // it was a C++ qualified type name.
         BeginLoc = SS.getBeginLoc();
@@ -1726,6 +1761,8 @@ bool Parser::TryAnnotateTypeOrScopeTokenAfterScopeSpec(bool EnteringContext,
                                                    NewEndLoc);
         if (NewType.isUsable())
           Ty = NewType.get();
+        else if (Tok.is(tok::eof)) // Nothing to do here, bail out...
+          return false;
       }
 
       // This is a typename. Replace the current token in-place with an
@@ -1754,11 +1791,11 @@ bool Parser::TryAnnotateTypeOrScopeTokenAfterScopeSpec(bool EnteringContext,
       UnqualifiedId TemplateName;
       TemplateName.setIdentifier(Tok.getIdentifierInfo(), Tok.getLocation());
       bool MemberOfUnknownSpecialization;
-      if (TemplateNameKind TNK =
-              Actions.isTemplateName(getCurScope(), SS,
-                                     /*hasTemplateKeyword=*/false, TemplateName,
-                                     /*ObjectType=*/nullptr, EnteringContext,
-                                     Template, MemberOfUnknownSpecialization)) {
+      if (TemplateNameKind TNK = Actions.isTemplateName(
+              getCurScope(), SS,
+              /*hasTemplateKeyword=*/false, TemplateName,
+              /*ObjectType=*/nullptr, /*EnteringContext*/false, Template,
+              MemberOfUnknownSpecialization)) {
         // Consume the identifier.
         ConsumeToken();
         if (AnnotateTemplateIdToken(Template, TNK, SS, SourceLocation(),
@@ -1988,7 +2025,6 @@ void Parser::ParseMicrosoftIfExistsExternalDeclaration() {
   while (Tok.isNot(tok::r_brace) && !isEofOrEom()) {
     ParsedAttributesWithRange attrs(AttrFactory);
     MaybeParseCXX11Attributes(attrs);
-    MaybeParseMicrosoftAttributes(attrs);
     DeclGroupPtrTy Result = ParseExternalDeclaration(attrs);
     if (Result && !getCurScope()->getParent())
       Actions.getASTConsumer().HandleTopLevelDecl(Result.get());
@@ -1996,51 +2032,122 @@ void Parser::ParseMicrosoftIfExistsExternalDeclaration() {
   Braces.consumeClose();
 }
 
+/// Parse a C++ Modules TS module declaration, which appears at the beginning
+/// of a module interface, module partition, or module implementation file.
+///
+///   module-declaration:   [Modules TS + P0273R0]
+///     'module' module-kind[opt] module-name attribute-specifier-seq[opt] ';'
+///   module-kind:
+///     'implementation'
+///     'partition'
+///
+/// Note that the module-kind values are context-sensitive keywords.
+Parser::DeclGroupPtrTy Parser::ParseModuleDecl() {
+  assert(Tok.is(tok::kw_module) && getLangOpts().ModulesTS &&
+         "should not be parsing a module declaration");
+  SourceLocation ModuleLoc = ConsumeToken();
+
+  // Check for a module-kind.
+  Sema::ModuleDeclKind MDK = Sema::ModuleDeclKind::Module;
+  if (Tok.is(tok::identifier) && NextToken().is(tok::identifier)) {
+    if (Tok.getIdentifierInfo()->isStr("implementation"))
+      MDK = Sema::ModuleDeclKind::Implementation;
+    else if (Tok.getIdentifierInfo()->isStr("partition"))
+      MDK = Sema::ModuleDeclKind::Partition;
+    else {
+      Diag(Tok, diag::err_unexpected_module_kind) << Tok.getIdentifierInfo();
+      SkipUntil(tok::semi);
+      return nullptr;
+    }
+    ConsumeToken();
+  }
+
+  SmallVector<std::pair<IdentifierInfo *, SourceLocation>, 2> Path;
+  if (ParseModuleName(ModuleLoc, Path, /*IsImport*/false))
+    return nullptr;
+
+  ParsedAttributesWithRange Attrs(AttrFactory);
+  MaybeParseCXX11Attributes(Attrs);
+  // We don't support any module attributes yet.
+  ProhibitCXX11Attributes(Attrs, diag::err_attribute_not_module_attr);
+
+  ExpectAndConsumeSemi(diag::err_module_expected_semi);
+
+  return Actions.ActOnModuleDecl(ModuleLoc, MDK, Path);
+}
+
+/// Parse a module import declaration. This is essentially the same for
+/// Objective-C and the C++ Modules TS, except for the leading '@' (in ObjC)
+/// and the trailing optional attributes (in C++).
+/// 
+/// [ObjC]  @import declaration:
+///           '@' 'import' module-name ';'
+/// [ModTS] module-import-declaration:
+///           'import' module-name attribute-specifier-seq[opt] ';'
 Parser::DeclGroupPtrTy Parser::ParseModuleImport(SourceLocation AtLoc) {
-  assert(Tok.isObjCAtKeyword(tok::objc_import) && 
+  assert((AtLoc.isInvalid() ? Tok.is(tok::kw_import)
+                            : Tok.isObjCAtKeyword(tok::objc_import)) &&
          "Improper start to module import");
   SourceLocation ImportLoc = ConsumeToken();
+  SourceLocation StartLoc = AtLoc.isInvalid() ? ImportLoc : AtLoc;
   
   SmallVector<std::pair<IdentifierInfo *, SourceLocation>, 2> Path;
-  
+  if (ParseModuleName(ImportLoc, Path, /*IsImport*/true))
+    return nullptr;
+
+  ParsedAttributesWithRange Attrs(AttrFactory);
+  MaybeParseCXX11Attributes(Attrs);
+  // We don't support any module import attributes yet.
+  ProhibitCXX11Attributes(Attrs, diag::err_attribute_not_import_attr);
+
+  if (PP.hadModuleLoaderFatalFailure()) {
+    // With a fatal failure in the module loader, we abort parsing.
+    cutOffParsing();
+    return nullptr;
+  }
+
+  DeclResult Import = Actions.ActOnModuleImport(StartLoc, ImportLoc, Path);
+  ExpectAndConsumeSemi(diag::err_module_expected_semi);
+  if (Import.isInvalid())
+    return nullptr;
+
+  return Actions.ConvertDeclToDeclGroup(Import.get());
+}
+
+/// Parse a C++ Modules TS / Objective-C module name (both forms use the same
+/// grammar).
+///
+///         module-name:
+///           module-name-qualifier[opt] identifier
+///         module-name-qualifier:
+///           module-name-qualifier[opt] identifier '.'
+bool Parser::ParseModuleName(
+    SourceLocation UseLoc,
+    SmallVectorImpl<std::pair<IdentifierInfo *, SourceLocation>> &Path,
+    bool IsImport) {
   // Parse the module path.
-  do {
+  while (true) {
     if (!Tok.is(tok::identifier)) {
       if (Tok.is(tok::code_completion)) {
-        Actions.CodeCompleteModuleImport(ImportLoc, Path);
+        Actions.CodeCompleteModuleImport(UseLoc, Path);
         cutOffParsing();
-        return nullptr;
+        return true;
       }
       
-      Diag(Tok, diag::err_module_expected_ident);
+      Diag(Tok, diag::err_module_expected_ident) << IsImport;
       SkipUntil(tok::semi);
-      return nullptr;
+      return true;
     }
     
     // Record this part of the module path.
     Path.push_back(std::make_pair(Tok.getIdentifierInfo(), Tok.getLocation()));
     ConsumeToken();
-    
-    if (Tok.is(tok::period)) {
-      ConsumeToken();
-      continue;
-    }
-    
-    break;
-  } while (true);
-
-  if (PP.hadModuleLoaderFatalFailure()) {
-    // With a fatal failure in the module loader, we abort parsing.
-    cutOffParsing();
-    return nullptr;
-  }
 
-  DeclResult Import = Actions.ActOnModuleImport(AtLoc, ImportLoc, Path);
-  ExpectAndConsumeSemi(diag::err_module_expected_semi);
-  if (Import.isInvalid())
-    return nullptr;
+    if (Tok.isNot(tok::period))
+      return false;
 
-  return Actions.ConvertDeclToDeclGroup(Import.get());
+    ConsumeToken();
+  }
 }
 
 /// \brief Try recover parser when module annotation appears where it must not
@@ -2051,19 +2158,35 @@ bool Parser::parseMisplacedModuleImport() {
   while (true) {
     switch (Tok.getKind()) {
     case tok::annot_module_end:
+      // If we recovered from a misplaced module begin, we expect to hit a
+      // misplaced module end too. Stay in the current context when this
+      // happens.
+      if (MisplacedModuleBeginCount) {
+        --MisplacedModuleBeginCount;
+        Actions.ActOnModuleEnd(Tok.getLocation(),
+                               reinterpret_cast<Module *>(
+                                   Tok.getAnnotationValue()));
+        ConsumeToken();
+        continue;
+      }
       // Inform caller that recovery failed, the error must be handled at upper
-      // level.
+      // level. This will generate the desired "missing '}' at end of module"
+      // diagnostics on the way out.
       return true;
     case tok::annot_module_begin:
-      Actions.diagnoseMisplacedModuleImport(reinterpret_cast<Module *>(
-        Tok.getAnnotationValue()), Tok.getLocation());
-      return true;
+      // Recover by entering the module (Sema will diagnose).
+      Actions.ActOnModuleBegin(Tok.getLocation(),
+                               reinterpret_cast<Module *>(
+                                   Tok.getAnnotationValue()));
+      ConsumeToken();
+      ++MisplacedModuleBeginCount;
+      continue;
     case tok::annot_module_include:
       // Module import found where it should not be, for instance, inside a
       // namespace. Recover by importing the module.
       Actions.ActOnModuleInclude(Tok.getLocation(),
                                  reinterpret_cast<Module *>(
-                                 Tok.getAnnotationValue()));
+                                     Tok.getAnnotationValue()));
       ConsumeToken();
       // If there is another module import, process it.
       continue;