[MSVC] Implementation of __unaligned as a proper type qualifier

This patch implements __unaligned (MS extension) as a proper type qualifier
(before that, it was implemented as an ignored attribute).

It also fixes PR27367 and PR27666.

Differential Revision: http://reviews.llvm.org/D20103


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@269220 91177308-0d34-0410-b5e6-96231b3b80d8

23 files changed, 255 insertions, 55 deletions

diff --git a/include/clang/AST/Type.h b/include/clang/AST/Type.h
index 71004fc572..09b3fc79b8 100644
--- a/include/clang/AST/Type.h
+++ b/include/clang/AST/Type.h
@@ -111,6 +111,7 @@ namespace clang {
 /// The collection of all-type qualifiers we support.
 /// Clang supports five independent qualifiers:
 /// * C99: const, volatile, and restrict
+/// * MS: __unaligned
 /// * Embedded C (TR18037): address spaces
 /// * Objective C: the GC attributes (none, weak, or strong)
 class Qualifiers {
@@ -152,8 +153,8 @@ public:
 
   enum {
     /// The maximum supported address space number.
-    /// 24 bits should be enough for anyone.
-    MaxAddressSpace = 0xffffffu,
+    /// 23 bits should be enough for anyone.
+    MaxAddressSpace = 0x7fffffu,
 
     /// The width of the "fast" qualifier mask.
     FastWidth = 3,
@@ -265,6 +266,13 @@ public:
     Mask |= mask;
   }
 
+  bool hasUnaligned() const { return Mask & UMask; }
+  void setUnaligned(bool flag) {
+    Mask = (Mask & ~UMask) | (flag ? UMask : 0);
+  }
+  void removeUnaligned() { Mask &= ~UMask; }
+  void addUnaligned() { Mask |= UMask; }
+
   bool hasObjCGCAttr() const { return Mask & GCAttrMask; }
   GC getObjCGCAttr() const { return GC((Mask & GCAttrMask) >> GCAttrShift); }
   void setObjCGCAttr(GC type) {
@@ -433,7 +441,9 @@ public:
            // ObjC lifetime qualifiers must match exactly.
            getObjCLifetime() == other.getObjCLifetime() &&
            // CVR qualifiers may subset.
-           (((Mask & CVRMask) | (other.Mask & CVRMask)) == (Mask & CVRMask));
+           (((Mask & CVRMask) | (other.Mask & CVRMask)) == (Mask & CVRMask)) &&
+           // U qualifier may superset.
+           (!other.hasUnaligned() || hasUnaligned());
   }
 
   /// \brief Determines if these qualifiers compatibly include another set of
@@ -501,16 +511,19 @@ public:
 
 private:
 
-  // bits:     |0 1 2|3 .. 4|5  ..  7|8   ...   31|
-  //           |C R V|GCAttr|Lifetime|AddressSpace|
+  // bits:     |0 1 2|3|4 .. 5|6  ..  8|9   ...   31|
+  //           |C R V|U|GCAttr|Lifetime|AddressSpace|
   uint32_t Mask;
 
-  static const uint32_t GCAttrMask = 0x18;
-  static const uint32_t GCAttrShift = 3;
-  static const uint32_t LifetimeMask = 0xE0;
-  static const uint32_t LifetimeShift = 5;
-  static const uint32_t AddressSpaceMask = ~(CVRMask|GCAttrMask|LifetimeMask);
-  static const uint32_t AddressSpaceShift = 8;
+  static const uint32_t UMask = 0x8;
+  static const uint32_t UShift = 3;
+  static const uint32_t GCAttrMask = 0x30;
+  static const uint32_t GCAttrShift = 4;
+  static const uint32_t LifetimeMask = 0x1C0;
+  static const uint32_t LifetimeShift = 6;
+  static const uint32_t AddressSpaceMask =
+      ~(CVRMask | UMask | GCAttrMask | LifetimeMask);
+  static const uint32_t AddressSpaceShift = 9;
 };
 
 /// A std::pair-like structure for storing a qualified type split
@@ -5367,9 +5380,9 @@ inline FunctionType::ExtInfo getFunctionExtInfo(QualType t) {
 /// "int". However, it is not more qualified than "const volatile
 /// int".
 inline bool QualType::isMoreQualifiedThan(QualType other) const {
-  Qualifiers myQuals = getQualifiers();
-  Qualifiers otherQuals = other.getQualifiers();
-  return (myQuals != otherQuals && myQuals.compatiblyIncludes(otherQuals));
+  Qualifiers MyQuals = getQualifiers();
+  Qualifiers OtherQuals = other.getQualifiers();
+  return (MyQuals != OtherQuals && MyQuals.compatiblyIncludes(OtherQuals));
 }
 
 /// Determine whether this type is at last
@@ -5377,7 +5390,13 @@ inline bool QualType::isMoreQualifiedThan(QualType other) const {
 /// int" is at least as qualified as "const int", "volatile int",
 /// "int", and "const volatile int".
 inline bool QualType::isAtLeastAsQualifiedAs(QualType other) const {
-  return getQualifiers().compatiblyIncludes(other.getQualifiers());
+  Qualifiers OtherQuals = other.getQualifiers();
+
+  // Ignore __unaligned qualifier if this type is a void.
+  if (getUnqualifiedType()->isVoidType())
+    OtherQuals.removeUnaligned();
+
+  return getQualifiers().compatiblyIncludes(OtherQuals);
 }
 
 /// If Type is a reference type (e.g., const
diff --git a/include/clang/Basic/AddressSpaces.h b/include/clang/Basic/AddressSpaces.h
index 8dd75660c6..63df61bedb 100644
--- a/include/clang/Basic/AddressSpaces.h
+++ b/include/clang/Basic/AddressSpaces.h
@@ -25,7 +25,7 @@ namespace LangAS {
 /// This uses a high starting offset so as not to conflict with any address
 /// space used by a target.
 enum ID {
-  Offset = 0xFFFF00,
+  Offset = 0x7FFF00,
 
   opencl_global = Offset,
   opencl_local,
diff --git a/include/clang/Basic/Attr.td b/include/clang/Basic/Attr.td
index e3c5e44265..8bc5dfcadc 100644
--- a/include/clang/Basic/Attr.td
+++ b/include/clang/Basic/Attr.td
@@ -2157,10 +2157,6 @@ def InitSeg : Attr {
   }];
 }
 
-def Unaligned : IgnoredAttr {
-  let Spellings = [Keyword<"__unaligned">];
-}
-
 def LoopHint : Attr {
   /// #pragma clang loop <option> directive
   /// vectorize: vectorizes loop operations if State == Enable.
diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index 4da2d28905..3a849b556f 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3374,6 +3374,16 @@ def note_ovl_candidate_bad_cvr : Note<"candidate "
     "%select{const|restrict|const and restrict|volatile|const and volatile|"
     "volatile and restrict|const, volatile, and restrict}3 qualifier"
     "%select{||s||s|s|s}3">;
+def note_ovl_candidate_bad_unaligned : Note<"candidate "
+    "%select{function|function|constructor|"
+    "function |function |constructor |"
+    "constructor (the implicit default constructor)|"
+    "constructor (the implicit copy constructor)|"
+    "constructor (the implicit move constructor)|"
+    "function (the implicit copy assignment operator)|"
+    "function (the implicit move assignment operator)|"
+    "constructor (inherited)}0%1 not viable: "
+    "%ordinal4 argument (%2) would lose __unaligned qualifier">;
 def note_ovl_candidate_bad_base_to_derived_conv : Note<"candidate "
     "%select{function|function|constructor|"
     "function |function |constructor |"
diff --git a/include/clang/Sema/DeclSpec.h b/include/clang/Sema/DeclSpec.h
index d296e74b07..0c4d94efbb 100644
--- a/include/clang/Sema/DeclSpec.h
+++ b/include/clang/Sema/DeclSpec.h
@@ -313,7 +313,10 @@ public:
     TQ_volatile    = 4,
     // This has no corresponding Qualifiers::TQ value, because it's not treated
     // as a qualifier in our type system.
-    TQ_atomic      = 8
+    TQ_atomic      = 8,
+    // There is no corresponding Qualifiers::TQ value, but it's kept separately
+    // in a dedicated Qualifiers::Mask bit.
+    TQ_unaligned   = 16
   };
 
   /// ParsedSpecifiers - Flags to query which specifiers were applied.  This is
@@ -344,7 +347,7 @@ private:
   unsigned TypeSpecPipe : 1;
 
   // type-qualifiers
-  unsigned TypeQualifiers : 4;  // Bitwise OR of TQ.
+  unsigned TypeQualifiers : 5;  // Bitwise OR of TQ.
 
   // function-specifier
   unsigned FS_inline_specified : 1;
@@ -386,7 +389,8 @@ private:
   /// TSTNameLoc provides source range info for tag types.
   SourceLocation TSTNameLoc;
   SourceRange TypeofParensRange;
-  SourceLocation TQ_constLoc, TQ_restrictLoc, TQ_volatileLoc, TQ_atomicLoc;
+  SourceLocation TQ_constLoc, TQ_restrictLoc, TQ_volatileLoc, TQ_atomicLoc,
+      TQ_unalignedLoc;
   SourceLocation FS_inlineLoc, FS_virtualLoc, FS_explicitLoc, FS_noreturnLoc;
   SourceLocation FS_forceinlineLoc;
   SourceLocation FriendLoc, ModulePrivateLoc, ConstexprLoc, ConceptLoc;
@@ -540,6 +544,7 @@ public:
   SourceLocation getRestrictSpecLoc() const { return TQ_restrictLoc; }
   SourceLocation getVolatileSpecLoc() const { return TQ_volatileLoc; }
   SourceLocation getAtomicSpecLoc() const { return TQ_atomicLoc; }
+  SourceLocation getUnalignedSpecLoc() const { return TQ_unalignedLoc; }
   SourceLocation getPipeLoc() const { return TQ_pipeLoc; }
 
   /// \brief Clear out all of the type qualifiers.
@@ -549,6 +554,7 @@ public:
     TQ_restrictLoc = SourceLocation();
     TQ_volatileLoc = SourceLocation();
     TQ_atomicLoc = SourceLocation();
+    TQ_unalignedLoc = SourceLocation();
     TQ_pipeLoc = SourceLocation();
   }
 
@@ -1114,8 +1120,8 @@ struct DeclaratorChunk {
   };
 
   struct PointerTypeInfo : TypeInfoCommon {
-    /// The type qualifiers: const/volatile/restrict/atomic.
-    unsigned TypeQuals : 4;
+    /// The type qualifiers: const/volatile/restrict/atomic/unaligned.
+    unsigned TypeQuals : 5;
 
     /// The location of the const-qualifier, if any.
     unsigned ConstQualLoc;
@@ -1129,6 +1135,9 @@ struct DeclaratorChunk {
     /// The location of the _Atomic-qualifier, if any.
     unsigned AtomicQualLoc;
 
+    /// The location of the __unaligned-qualifier, if any.
+    unsigned UnalignedQualLoc;
+
     void destroy() {
     }
   };
@@ -1469,7 +1478,8 @@ struct DeclaratorChunk {
                                     SourceLocation ConstQualLoc,
                                     SourceLocation VolatileQualLoc,
                                     SourceLocation RestrictQualLoc,
-                                    SourceLocation AtomicQualLoc) {
+                                    SourceLocation AtomicQualLoc,
+                                    SourceLocation UnalignedQualLoc) {
     DeclaratorChunk I;
     I.Kind                = Pointer;
     I.Loc                 = Loc;
@@ -1478,6 +1488,7 @@ struct DeclaratorChunk {
     I.Ptr.VolatileQualLoc = VolatileQualLoc.getRawEncoding();
     I.Ptr.RestrictQualLoc = RestrictQualLoc.getRawEncoding();
     I.Ptr.AtomicQualLoc   = AtomicQualLoc.getRawEncoding();
+    I.Ptr.UnalignedQualLoc = UnalignedQualLoc.getRawEncoding();
     I.Ptr.AttrList        = nullptr;
     return I;
   }
diff --git a/include/clang/Sema/Sema.h b/include/clang/Sema/Sema.h
index d7e56f78f7..dff303124d 100644
--- a/include/clang/Sema/Sema.h
+++ b/include/clang/Sema/Sema.h
@@ -1675,7 +1675,8 @@ public:
                             SourceLocation ConstQualLoc = SourceLocation(),
                             SourceLocation VolatileQualLoc = SourceLocation(),
                             SourceLocation RestrictQualLoc = SourceLocation(),
-                            SourceLocation AtomicQualLoc = SourceLocation());
+                            SourceLocation AtomicQualLoc = SourceLocation(),
+                            SourceLocation UnalignedQualLoc = SourceLocation());
 
   static bool adjustContextForLocalExternDecl(DeclContext *&DC);
   void DiagnoseFunctionSpecifiers(const DeclSpec &DS);
diff --git a/lib/AST/MicrosoftMangle.cpp b/lib/AST/MicrosoftMangle.cpp
index c9caddbb6f..774dab0572 100644
--- a/lib/AST/MicrosoftMangle.cpp
+++ b/lib/AST/MicrosoftMangle.cpp
@@ -1446,6 +1446,9 @@ void MicrosoftCXXNameMangler::manglePointerExtQualifiers(Qualifiers Quals,
 
   if (HasRestrict)
     Out << 'I';
+
+  if (!PointeeType.isNull() && PointeeType.getLocalQualifiers().hasUnaligned())
+    Out << 'F';
 }
 
 void MicrosoftCXXNameMangler::manglePointerCVQualifiers(Qualifiers Quals) {
@@ -1577,6 +1580,8 @@ void MicrosoftCXXNameMangler::mangleType(QualType T, SourceRange Range,
     }
     break;
   case QMM_Result:
+    // Presence of __unaligned qualifier shouldn't affect mangling here.
+    Quals.removeUnaligned();
     if ((!IsPointer && Quals) || isa<TagType>(T)) {
       Out << '?';
       mangleQualifiers(Quals, false);
diff --git a/lib/AST/TypePrinter.cpp b/lib/AST/TypePrinter.cpp
index 0356dc515f..7e04e81e8d 100644
--- a/lib/AST/TypePrinter.cpp
+++ b/lib/AST/TypePrinter.cpp
@@ -1593,6 +1593,12 @@ void Qualifiers::print(raw_ostream &OS, const PrintingPolicy& Policy,
     AppendTypeQualList(OS, quals, Policy.LangOpts.C99);
     addSpace = true;
   }
+  if (hasUnaligned()) {
+    if (addSpace)
+      OS << ' ';
+    OS << "__unaligned";
+    addSpace = true;
+  }
   if (unsigned addrspace = getAddressSpace()) {
     if (addSpace)
       OS << ' ';
diff --git a/lib/Parse/ParseDecl.cpp b/lib/Parse/ParseDecl.cpp
index 2171e5cfc3..1c93c08f71 100644
--- a/lib/Parse/ParseDecl.cpp
+++ b/lib/Parse/ParseDecl.cpp
@@ -609,7 +609,6 @@ void Parser::ParseMicrosoftTypeAttributes(ParsedAttributes &attrs) {
     case tok::kw___ptr64:
     case tok::kw___w64:
     case tok::kw___ptr32:
-    case tok::kw___unaligned:
     case tok::kw___sptr:
     case tok::kw___uptr: {
       IdentifierInfo *AttrName = Tok.getIdentifierInfo();
@@ -3087,6 +3086,11 @@ void Parser::ParseDeclarationSpecifiers(DeclSpec &DS,
       break;
     }
 
+    case tok::kw___unaligned:
+      isInvalid = DS.SetTypeQual(DeclSpec::TQ_unaligned, Loc, PrevSpec, DiagID,
+                                 getLangOpts());
+      break;
+
     case tok::kw___sptr:
     case tok::kw___uptr:
     case tok::kw___ptr64:
@@ -3097,7 +3101,6 @@ void Parser::ParseDeclarationSpecifiers(DeclSpec &DS,
     case tok::kw___fastcall:
     case tok::kw___thiscall:
     case tok::kw___vectorcall:
-    case tok::kw___unaligned:
       ParseMicrosoftTypeAttributes(DS.getAttributes());
       continue;
 
@@ -4798,6 +4801,10 @@ void Parser::ParseTypeQualifierListOpt(DeclSpec &DS, unsigned AttrReqs,
       ParseOpenCLQualifiers(DS.getAttributes());
       break;
 
+    case tok::kw___unaligned:
+      isInvalid = DS.SetTypeQual(DeclSpec::TQ_unaligned, Loc, PrevSpec, DiagID,
+                                 getLangOpts());
+      break;
     case tok::kw___uptr:
       // GNU libc headers in C mode use '__uptr' as an identifer which conflicts
       // with the MS modifier keyword.
@@ -4815,7 +4822,6 @@ void Parser::ParseTypeQualifierListOpt(DeclSpec &DS, unsigned AttrReqs,
     case tok::kw___fastcall:
     case tok::kw___thiscall:
     case tok::kw___vectorcall:
-    case tok::kw___unaligned:
       if (AttrReqs & AR_DeclspecAttributesParsed) {
         ParseMicrosoftTypeAttributes(DS.getAttributes());
         continue;
@@ -5038,7 +5044,8 @@ void Parser::ParseDeclaratorInternal(Declarator &D,
                                                 DS.getConstSpecLoc(),
                                                 DS.getVolatileSpecLoc(),
                                                 DS.getRestrictSpecLoc(),
-                                                DS.getAtomicSpecLoc()),
+                                                DS.getAtomicSpecLoc(),
+                                                DS.getUnalignedSpecLoc()),
                     DS.getAttributes(),
                     SourceLocation());
     else
diff --git a/lib/Parse/ParseTentative.cpp b/lib/Parse/ParseTentative.cpp
index 4d4bd806f3..cde558196d 100644
--- a/lib/Parse/ParseTentative.cpp
+++ b/lib/Parse/ParseTentative.cpp
@@ -833,7 +833,7 @@ Parser::TPResult Parser::TryParseDeclarator(bool mayBeAbstract,
       // '(' abstract-declarator ')'
       if (Tok.isOneOf(tok::kw___attribute, tok::kw___declspec, tok::kw___cdecl,
                       tok::kw___stdcall, tok::kw___fastcall, tok::kw___thiscall,
-                      tok::kw___vectorcall, tok::kw___unaligned))
+                      tok::kw___vectorcall))
         return TPResult::True; // attributes indicate declaration
       TPResult TPR = TryParseDeclarator(mayBeAbstract, mayHaveIdentifier);
       if (TPR != TPResult::Ambiguous)
diff --git a/lib/Sema/DeclSpec.cpp b/lib/Sema/DeclSpec.cpp
index ddfe6257cf..de013afa14 100644
--- a/lib/Sema/DeclSpec.cpp
+++ b/lib/Sema/DeclSpec.cpp
@@ -494,6 +494,7 @@ const char *DeclSpec::getSpecifierName(TQ T) {
   case DeclSpec::TQ_restrict:    return "restrict";
   case DeclSpec::TQ_volatile:    return "volatile";
   case DeclSpec::TQ_atomic:      return "_Atomic";
+  case DeclSpec::TQ_unaligned:   return "__unaligned";
   }
   llvm_unreachable("Unknown typespec!");
 }
@@ -796,6 +797,7 @@ bool DeclSpec::SetTypeQual(TQ T, SourceLocation Loc, const char *&PrevSpec,
   case TQ_restrict: TQ_restrictLoc = Loc; return false;
   case TQ_volatile: TQ_volatileLoc = Loc; return false;
   case TQ_atomic:   TQ_atomicLoc = Loc; return false;
+  case TQ_unaligned: TQ_unalignedLoc = Loc; return false;
   }
 
   llvm_unreachable("Unknown type qualifier!");
@@ -961,10 +963,10 @@ void DeclSpec::Finish(Sema &S, const PrintingPolicy &Policy) {
        TypeSpecSign != TSS_unspecified ||
        TypeAltiVecVector || TypeAltiVecPixel || TypeAltiVecBool ||
        TypeQualifiers)) {
-    const unsigned NumLocs = 8;
+    const unsigned NumLocs = 9;
     SourceLocation ExtraLocs[NumLocs] = {
       TSWLoc, TSCLoc, TSSLoc, AltiVecLoc,
-      TQ_constLoc, TQ_restrictLoc, TQ_volatileLoc, TQ_atomicLoc
+      TQ_constLoc, TQ_restrictLoc, TQ_volatileLoc, TQ_atomicLoc, TQ_unalignedLoc
     };
     FixItHint Hints[NumLocs];
     SourceLocation FirstLoc;
diff --git a/lib/Sema/SemaCodeComplete.cpp b/lib/Sema/SemaCodeComplete.cpp
index ab2e718c85..739d70288c 100644
--- a/lib/Sema/SemaCodeComplete.cpp
+++ b/lib/Sema/SemaCodeComplete.cpp
@@ -3812,6 +3812,9 @@ void Sema::CodeCompleteTypeQualifiers(DeclSpec &DS) {
   if (getLangOpts().C11 &&
       !(DS.getTypeQualifiers() & DeclSpec::TQ_atomic))
     Results.AddResult("_Atomic");
+  if (getLangOpts().MSVCCompat &&
+      !(DS.getTypeQualifiers() & DeclSpec::TQ_unaligned))
+    Results.AddResult("__unaligned");
   Results.ExitScope();
   HandleCodeCompleteResults(this, CodeCompleter, 
                             Results.getCompletionContext(),
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 020b474c18..75aca834d2 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -3985,6 +3985,8 @@ Sema::ParsedFreeStandingDeclSpec(Scope *S, AccessSpecifier AS, DeclSpec &DS,
     // Restrict is covered above.
     if (DS.getTypeQualifiers() & DeclSpec::TQ_atomic)
       Diag(DS.getAtomicSpecLoc(), DiagID) << "_Atomic";
+    if (DS.getTypeQualifiers() & DeclSpec::TQ_unaligned)
+      Diag(DS.getUnalignedSpecLoc(), DiagID) << "__unaligned";
   }
 
   // Warn about ignored type attributes, for example:
@@ -4242,6 +4244,11 @@ Decl *Sema::BuildAnonymousStructOrUnion(Scope *S, DeclSpec &DS,
              diag::ext_anonymous_struct_union_qualified)
           << Record->isUnion() << "_Atomic"
           << FixItHint::CreateRemoval(DS.getAtomicSpecLoc());
+      if (DS.getTypeQualifiers() & DeclSpec::TQ_unaligned)
+        Diag(DS.getUnalignedSpecLoc(),
+             diag::ext_anonymous_struct_union_qualified)
+          << Record->isUnion() << "__unaligned"
+          << FixItHint::CreateRemoval(DS.getUnalignedSpecLoc());
 
       DS.ClearTypeQualifiers();
     }
diff --git a/lib/Sema/SemaDeclObjC.cpp b/lib/Sema/SemaDeclObjC.cpp
index 400dc63775..3fb29d46cf 100644
--- a/lib/Sema/SemaDeclObjC.cpp
+++ b/lib/Sema/SemaDeclObjC.cpp
@@ -1503,6 +1503,7 @@ void Sema::actOnObjCTypeArgsOrProtocolQualifiers(
                                                 SourceLocation(),
                                                 SourceLocation(),
                                                 SourceLocation(),
+                                                SourceLocation(),
                                                 SourceLocation()),
                                                 parsedAttrs,
                                                 starLoc);
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index a5ee8bebae..68fd92fbe1 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -7140,7 +7140,7 @@ checkPointerTypesForAssignment(Sema &S, QualType LHSType, QualType RHSType) {
     else if (lhq.getObjCLifetime() != rhq.getObjCLifetime())
       ConvTy = Sema::IncompatiblePointerDiscardsQualifiers;
     
-    // For GCC compatibility, other qualifier mismatches are treated
+    // For GCC/MS compatibility, other qualifier mismatches are treated
     // as still compatible in C.
     else ConvTy = Sema::CompatiblePointerDiscardsQualifiers;
   }
diff --git a/lib/Sema/SemaOverload.cpp b/lib/Sema/SemaOverload.cpp
index 481c245bdd..415eda02ec 100644
--- a/lib/Sema/SemaOverload.cpp
+++ b/lib/Sema/SemaOverload.cpp
@@ -2951,6 +2951,10 @@ Sema::IsQualificationConversion(QualType FromType, QualType ToType,
 
     Qualifiers FromQuals = FromType.getQualifiers();
     Qualifiers ToQuals = ToType.getQualifiers();
+
+    // Ignore __unaligned qualifier if this type is void.
+    if (ToType.getUnqualifiedType()->isVoidType())
+      FromQuals.removeUnaligned();
     
     // Objective-C ARC:
     //   Check Objective-C lifetime conversions.
@@ -4159,6 +4163,10 @@ Sema::CompareReferenceRelationship(SourceLocation Loc,
     T2Quals.removeObjCLifetime();    
   }
     
+  // MS compiler ignores __unaligned qualifier for references; do the same.
+  T1Quals.removeUnaligned();
+  T2Quals.removeUnaligned();
+
   if (T1Quals == T2Quals)
     return Ref_Compatible;
   else if (T1Quals.compatiblyIncludes(T2Quals))
@@ -4480,13 +4488,16 @@ TryReferenceInit(Sema &S, Expr *Init, QualType DeclType,
     // initialization fails.
     //
     // Note that we only want to check address spaces and cvr-qualifiers here.
-    // ObjC GC and lifetime qualifiers aren't important.
+    // ObjC GC, lifetime and unaligned qualifiers aren't important.
     Qualifiers T1Quals = T1.getQualifiers();
     Qualifiers T2Quals = T2.getQualifiers();
     T1Quals.removeObjCGCAttr();
     T1Quals.removeObjCLifetime();
     T2Quals.removeObjCGCAttr();
     T2Quals.removeObjCLifetime();
+    // MS compiler ignores __unaligned qualifier for references; do the same.
+    T1Quals.removeUnaligned();
+    T2Quals.removeUnaligned();
     if (!T1Quals.compatiblyIncludes(T2Quals))
       return ICS;
   }
@@ -9135,6 +9146,15 @@ static void DiagnoseBadConversion(Sema &S, OverloadCandidate *Cand,
       return;
     }
 
+    if (FromQs.hasUnaligned() != ToQs.hasUnaligned()) {
+      S.Diag(Fn->getLocation(), diag::note_ovl_candidate_bad_unaligned)
+        << (unsigned) FnKind << FnDesc
+        << (FromExpr ? FromExpr->getSourceRange() : SourceRange())
+        << FromTy << FromQs.hasUnaligned() << I+1;
+      MaybeEmitInheritedConstructorNote(S, Fn);
+      return;
+    }
+
     unsigned CVR = FromQs.getCVRQualifiers() & ~ToQs.getCVRQualifiers();
     assert(CVR && "unexpected qualifiers mismatch");
 
diff --git a/lib/Sema/SemaType.cpp b/lib/Sema/SemaType.cpp
index 7fd43a87a8..57295fde0b 100644
--- a/lib/Sema/SemaType.cpp
+++ b/lib/Sema/SemaType.cpp
@@ -1785,12 +1785,13 @@ QualType Sema::BuildQualifiedType(QualType T, SourceLocation Loc,
 }
 
 QualType Sema::BuildQualifiedType(QualType T, SourceLocation Loc,
-                                  unsigned CVRA, const DeclSpec *DS) {
+                                  unsigned CVRAU, const DeclSpec *DS) {
   if (T.isNull())
     return QualType();
 
-  // Convert from DeclSpec::TQ to Qualifiers::TQ by just dropping TQ_atomic.
-  unsigned CVR = CVRA & ~DeclSpec::TQ_atomic;
+  // Convert from DeclSpec::TQ to Qualifiers::TQ by just dropping TQ_atomic and
+  // TQ_unaligned;
+  unsigned CVR = CVRAU & ~(DeclSpec::TQ_atomic | DeclSpec::TQ_unaligned);
 
   // C11 6.7.3/5:
   //   If the same qualifier appears more than once in the same
@@ -1800,7 +1801,7 @@ QualType Sema::BuildQualifiedType(QualType T, SourceLocation Loc,
   // It's not specified what happens when the _Atomic qualifier is applied to
   // a type specified with the _Atomic specifier, but we assume that this
   // should be treated as if the _Atomic qualifier appeared multiple times.
-  if (CVRA & DeclSpec::TQ_atomic && !T->isAtomicType()) {
+  if (CVRAU & DeclSpec::TQ_atomic && !T->isAtomicType()) {
     // C11 6.7.3/5:
     //   If other qualifiers appear along with the _Atomic qualifier in a
     //   specifier-qualifier-list, the resulting type is the so-qualified
@@ -1817,7 +1818,9 @@ QualType Sema::BuildQualifiedType(QualType T, SourceLocation Loc,
     return BuildQualifiedType(T, Loc, Split.Quals);
   }
 
-  return BuildQualifiedType(T, Loc, Qualifiers::fromCVRMask(CVR), DS);
+  Qualifiers Q = Qualifiers::fromCVRMask(CVR);
+  Q.setUnaligned(CVRAU & DeclSpec::TQ_unaligned);
+  return BuildQualifiedType(T, Loc, Q, DS);
 }
 
 /// \brief Build a paren type including \p T.
@@ -2652,7 +2655,8 @@ void Sema::diagnoseIgnoredQualifiers(unsigned DiagID, unsigned Quals,
                                      SourceLocation ConstQualLoc,
                                      SourceLocation VolatileQualLoc,
                                      SourceLocation RestrictQualLoc,
-                                     SourceLocation AtomicQualLoc) {
+                                     SourceLocation AtomicQualLoc,
+                                     SourceLocation UnalignedQualLoc) {
   if (!Quals)
     return;
 
@@ -2660,26 +2664,27 @@ void Sema::diagnoseIgnoredQualifiers(unsigned DiagID, unsigned Quals,
     const char *Name;
     unsigned Mask;
     SourceLocation Loc;
-  } const QualKinds[4] = {
+  } const QualKinds[5] = {
     { "const", DeclSpec::TQ_const, ConstQualLoc },
     { "volatile", DeclSpec::TQ_volatile, VolatileQualLoc },
     { "restrict", DeclSpec::TQ_restrict, RestrictQualLoc },
-    { "_Atomic", DeclSpec::TQ_atomic, AtomicQualLoc }
+    { "_Atomic", DeclSpec::TQ_atomic, AtomicQualLoc },
+    { "__unaligned", DeclSpec::TQ_unaligned, UnalignedQualLoc }
   };
 
   SmallString<32> QualStr;
   unsigned NumQuals = 0;
   SourceLocation Loc;
-  FixItHint FixIts[4];
+  FixItHint FixIts[5];
 
   // Build a string naming the redundant qualifiers.
-  for (unsigned I = 0; I != 4; ++I) {
-    if (Quals & QualKinds[I].Mask) {
+  for (auto &E : QualKinds) {
+    if (Quals & E.Mask) {
       if (!QualStr.empty()) QualStr += ' ';
-      QualStr += QualKinds[I].Name;
+      QualStr += E.Name;
 
       // If we have a location for the qualifier, offer a fixit.
-      SourceLocation QualLoc = QualKinds[I].Loc;
+      SourceLocation QualLoc = E.Loc;
       if (QualLoc.isValid()) {
         FixIts[NumQuals] = FixItHint::CreateRemoval(QualLoc);
         if (Loc.isInvalid() ||
@@ -2725,7 +2730,8 @@ static void diagnoseRedundantReturnTypeQualifiers(Sema &S, QualType RetTy,
           SourceLocation::getFromRawEncoding(PTI.ConstQualLoc),
           SourceLocation::getFromRawEncoding(PTI.VolatileQualLoc),
           SourceLocation::getFromRawEncoding(PTI.RestrictQualLoc),
-          SourceLocation::getFromRawEncoding(PTI.AtomicQualLoc));
+          SourceLocation::getFromRawEncoding(PTI.AtomicQualLoc),
+          SourceLocation::getFromRawEncoding(PTI.UnalignedQualLoc));
       return;
     }
 
@@ -2761,7 +2767,8 @@ static void diagnoseRedundantReturnTypeQualifiers(Sema &S, QualType RetTy,
                               D.getDeclSpec().getConstSpecLoc(),
                               D.getDeclSpec().getVolatileSpecLoc(),
                               D.getDeclSpec().getRestrictSpecLoc(),
-                              D.getDeclSpec().getAtomicSpecLoc());
+                              D.getDeclSpec().getAtomicSpecLoc(),
+                              D.getDeclSpec().getUnalignedSpecLoc());
 }
 
 static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
diff --git a/test/CodeGenCXX/mangle-ms-cxx11.cpp b/test/CodeGenCXX/mangle-ms-cxx11.cpp
index 99384440a1..12bb8c7ee5 100644
--- a/test/CodeGenCXX/mangle-ms-cxx11.cpp
+++ b/test/CodeGenCXX/mangle-ms-cxx11.cpp
@@ -293,3 +293,19 @@ int PR26105() {
 }
 // CHECK-DAG: @"\01??R<lambda_0>@?0??PR26105@@YAHXZ@QBE@H@Z"
 // CHECK-DAG: @"\01??R<lambda_1>@?0???R<lambda_0>@?0??PR26105@@YAHXZ@QBE@H@Z@QBE@H@Z"
+
+int __unaligned * unaligned_foo1() { return 0; }
+int __unaligned * __unaligned * unaligned_foo2() { return 0; }
+__unaligned int unaligned_foo3() { return 0; }
+void unaligned_foo4(int __unaligned *p1) {}
+void unaligned_foo5(int __unaligned * __restrict p1) {}
+template <typename T> T unaligned_foo6(T t) { return t; }
+void unaligned_foo7() { unaligned_foo6<int *>(0); unaligned_foo6<int __unaligned *>(0); }
+
+// CHECK-DAG: @"\01?unaligned_foo1@@YAPFAHXZ"
+// CHECK-DAG: @"\01?unaligned_foo2@@YAPFAPFAHXZ"
+// CHECK-DAG: @"\01?unaligned_foo3@@YAHXZ"
+// CHECK-DAG: @"\01?unaligned_foo4@@YAXPFAH@Z"
+// CHECK-DAG: @"\01?unaligned_foo5@@YAXPIFAH@Z"
+// CHECK-DAG: @"\01??$unaligned_foo6@PAH@@YAPAHPAH@Z"
+// CHECK-DAG: @"\01??$unaligned_foo6@PFAH@@YAPFAHPFAH@Z"
diff --git a/test/CodeGenCXX/mangle-ms-cxx14.cpp b/test/CodeGenCXX/mangle-ms-cxx14.cpp
index 084eb7ddf1..798a390aea 100644
--- a/test/CodeGenCXX/mangle-ms-cxx14.cpp
+++ b/test/CodeGenCXX/mangle-ms-cxx14.cpp
@@ -55,3 +55,8 @@ struct Foo {};
 
 Foo<&x<int>, &x<int>> Zoo;
 // CHECK-DAG: "\01?Zoo@@3U?$Foo@$1??$x@H@@3HA$1?1@3HA@@A"
+
+template <typename T> T unaligned_x;
+extern auto test_unaligned() { return unaligned_x<int __unaligned *>; }
+// CHECK-DAG: "\01??$unaligned_x@PFAH@@3PFAHA"
+
diff --git a/test/Sema/MicrosoftExtensions.c b/test/Sema/MicrosoftExtensions.c
index e7032305fc..713daf5593 100644
--- a/test/Sema/MicrosoftExtensions.c
+++ b/test/Sema/MicrosoftExtensions.c
@@ -170,3 +170,11 @@ void myprintf(const char *f, ...) {
     __va_start(ap, f); // expected-warning {{incompatible pointer types passing 'my_va_list'}}
   }
 }
+
+// __unaligned handling
+void test_unaligned() {
+  __unaligned int *p1 = 0;
+  int *p2 = p1; // expected-warning {{initializing 'int *' with an expression of type '__unaligned int *' discards qualifiers}}
+  __unaligned int *p3 = p2;
+}
+
diff --git a/test/Sema/address_spaces.c b/test/Sema/address_spaces.c
index 1922c8ae4f..3fe9315545 100644
--- a/test/Sema/address_spaces.c
+++ b/test/Sema/address_spaces.c
@@ -20,7 +20,7 @@ void foo(_AS3 float *a,
   _AS1 int arrarr[5][5]; // expected-error {{automatic variable qualified with an address space}}
 
   __attribute__((address_space(-1))) int *_boundsA; // expected-error {{address space is negative}}
-  __attribute__((address_space(0xFFFFFF))) int *_boundsB;
+  __attribute__((address_space(0x7FFFFF))) int *_boundsB;
   __attribute__((address_space(0x1000000))) int *_boundsC; // expected-error {{address space is larger than the maximum supported}}
   // chosen specifically to overflow 32 bits and come out reasonable
   __attribute__((address_space(4294967500))) int *_boundsD; // expected-error {{address space is larger than the maximum supported}}
@@ -71,4 +71,4 @@ __attribute__((address_space("12"))) int *i; // expected-error {{'address_space'
 // Clang extension doesn't forbid operations on pointers to different address spaces.
 char* cmp(_AS1 char *x,  _AS2 char *y) {
   return x < y ? x : y; // expected-warning {{pointer type mismatch ('__attribute__((address_space(1))) char *' and '__attribute__((address_space(2))) char *')}}
-}
\ No newline at end of file
+}
diff --git a/test/Sema/invalid-assignment-constant-address-space.c b/test/Sema/invalid-assignment-constant-address-space.c
index de2af64d00..77d6b331c2 100644
--- a/test/Sema/invalid-assignment-constant-address-space.c
+++ b/test/Sema/invalid-assignment-constant-address-space.c
@@ -1,6 +1,6 @@
 // RUN: %clang_cc1 %s -verify -pedantic -fsyntax-only
 
-#define OPENCL_CONSTANT 16776962
+#define OPENCL_CONSTANT 8388354
 int __attribute__((address_space(OPENCL_CONSTANT))) c[3] = {0};
 
 void foo() {
diff --git a/test/SemaCXX/MicrosoftExtensions.cpp b/test/SemaCXX/MicrosoftExtensions.cpp
index 22cf2be7c1..e24e45d871 100644
--- a/test/SemaCXX/MicrosoftExtensions.cpp
+++ b/test/SemaCXX/MicrosoftExtensions.cpp
@@ -1,5 +1,7 @@
-// RUN: %clang_cc1 %s -triple i686-pc-win32 -fsyntax-only -Wmicrosoft -Wc++11-extensions -Wno-long-long -verify -fms-extensions -fexceptions -fcxx-exceptions
+// RUN: %clang_cc1 %s -triple i686-pc-win32 -fsyntax-only -Wmicrosoft -Wc++11-extensions -Wno-long-long -verify -fms-extensions -fexceptions -fcxx-exceptions -DTEST1
+// RUN: %clang_cc1 %s -triple i686-pc-win32 -fsyntax-only -Wmicrosoft -Wc++11-extensions -Wno-long-long -verify -fexceptions -fcxx-exceptions -DTEST2
 
+#if TEST1
 
 // Microsoft doesn't validate exception specification.
 namespace microsoft_exception_spec {
@@ -80,7 +82,69 @@ struct M {
 // __unaligned handling
 typedef char __unaligned *aligned_type;
 typedef struct UnalignedTag { int f; } __unaligned *aligned_type2;
+typedef char __unaligned aligned_type3;
 
+struct aligned_type4 {
+  int i;
+};
+
+__unaligned int aligned_type4::*p1_aligned_type4 = &aligned_type4::i;
+int aligned_type4::* __unaligned p2_aligned_type4 = &aligned_type4::i;
+__unaligned int aligned_type4::* __unaligned p3_aligned_type4 = &aligned_type4::i;
+
+// Check that __unaligned qualifier can be used for overloading
+void foo_unaligned(int *arg) {}
+void foo_unaligned(__unaligned int *arg) {}
+void foo_unaligned(int arg) {} // expected-note {{previous definition is here}}
+void foo_unaligned(__unaligned int arg) {} // expected-error {{redefinition of 'foo_unaligned'}}
+class A_unaligned {};
+class B_unaligned : public A_unaligned {};
+int foo_unaligned(__unaligned A_unaligned *arg) { return 0; }
+void *foo_unaligned(B_unaligned *arg) { return 0; }
+
+void test_unaligned() {
+  int *p1 = 0;
+  foo_unaligned(p1);
+
+  __unaligned int *p2 = 0;
+  foo_unaligned(p2);
+
+  __unaligned B_unaligned *p3 = 0;
+  int p4 = foo_unaligned(p3);
+
+  B_unaligned *p5 = p3; // expected-error {{cannot initialize a variable of type 'B_unaligned *' with an lvalue of type '__unaligned B_unaligned *'}}
+
+  __unaligned B_unaligned *p6 = p3;
+
+  p1_aligned_type4 = p2_aligned_type4;
+  p2_aligned_type4 = p1_aligned_type4; // expected-error {{assigning to 'int aligned_type4::*' from incompatible type '__unaligned int aligned_type4::*'}}
+  p3_aligned_type4 = p1_aligned_type4;
+}
+
+// Test from PR27367
+// We should accept assignment of an __unaligned pointer to a non-__unaligned
+// pointer to void
+typedef struct _ITEMIDLIST { int i; } ITEMIDLIST;
+typedef ITEMIDLIST __unaligned *LPITEMIDLIST;
+extern "C" __declspec(dllimport) void __stdcall CoTaskMemFree(void* pv);
+__inline void FreeIDListArray(LPITEMIDLIST *ppidls) {
+  CoTaskMemFree(*ppidls);
+  __unaligned int *x = 0;
+  void *y = x;
+}
+
+// Test from PR27666
+// We should accept type conversion of __unaligned to non-__unaligned references
+typedef struct in_addr {
+public:
+  in_addr(in_addr &a) {} // expected-note {{candidate constructor not viable: no known conversion from '__unaligned IN_ADDR *' (aka '__unaligned in_addr *') to 'in_addr &' for 1st argument; dereference the argument with *}}
+  in_addr(in_addr *a) {} // expected-note {{candidate constructor not viable: 1st argument ('__unaligned IN_ADDR *' (aka '__unaligned in_addr *')) would lose __unaligned qualifier}}
+} IN_ADDR;
+
+void f(IN_ADDR __unaligned *a) {
+  IN_ADDR local_addr = *a;
+  IN_ADDR local_addr2 = a; // expected-error {{no viable conversion from '__unaligned IN_ADDR *' (aka '__unaligned in_addr *') to 'IN_ADDR' (aka 'in_addr')}}
+}
 
 template<typename T> void h1(T (__stdcall M::* const )()) { }
 
@@ -420,3 +484,15 @@ struct S {
 
 int S::fn() { return 0; } // expected-warning {{is missing exception specification}}
 }
+
+#elif TEST2
+
+// Check that __unaligned is not recognized if MS extensions are not enabled
+typedef char __unaligned *aligned_type; // expected-error {{expected ';' after top level declarator}}
+
+#else
+
+#error Unknown test mode
+
+#endif
+