[PATCH] D39008: [CodeGen] Propagate may-alias'ness of lvalues with TBAA info

2017-10-31 Thread Ivan Kosarev via Phabricator via cfe-commits 
This revision was automatically updated to reflect the committed changes.
Closed by commit rL316988: [CodeGen] Propagate may-alias'ness of lvalues with 
TBAA info (authored by kosarev).

Changed prior to commit:
  https://reviews.llvm.org/D39008?vs=120828&id=120958#toc

Repository:
  rL LLVM

https://reviews.llvm.org/D39008

Files:
  cfe/trunk/lib/CodeGen/CGExpr.cpp
  cfe/trunk/lib/CodeGen/CGObjCRuntime.cpp
  cfe/trunk/lib/CodeGen/CGOpenMPRuntime.cpp
  cfe/trunk/lib/CodeGen/CGValue.h
  cfe/trunk/lib/CodeGen/CodeGenFunction.cpp
  cfe/trunk/lib/CodeGen/CodeGenFunction.h
  cfe/trunk/lib/CodeGen/CodeGenModule.cpp
  cfe/trunk/lib/CodeGen/CodeGenModule.h
  cfe/trunk/lib/CodeGen/CodeGenTBAA.cpp
  cfe/trunk/lib/CodeGen/CodeGenTBAA.h

Index: cfe/trunk/lib/CodeGen/CodeGenFunction.h
===
--- cfe/trunk/lib/CodeGen/CodeGenFunction.h
+++ cfe/trunk/lib/CodeGen/CodeGenFunction.h
@@ -1919,8 +1919,7 @@
 
   LValue MakeAddrLValue(Address Addr, QualType T,
 AlignmentSource Source = AlignmentSource::Type) {
-return LValue::MakeAddr(Addr, T, getContext(),
-LValueBaseInfo(Source, false),
+return LValue::MakeAddr(Addr, T, getContext(), LValueBaseInfo(Source),
 CGM.getTBAAAccessInfo(T));
   }
 
@@ -1932,8 +1931,7 @@
   LValue MakeAddrLValue(llvm::Value *V, QualType T, CharUnits Alignment,
 AlignmentSource Source = AlignmentSource::Type) {
 return LValue::MakeAddr(Address(V, Alignment), T, getContext(),
-LValueBaseInfo(Source, false),
-CGM.getTBAAAccessInfo(T));
+LValueBaseInfo(Source), CGM.getTBAAAccessInfo(T));
   }
 
   LValue MakeAddrLValue(llvm::Value *V, QualType T, CharUnits Alignment,
@@ -3092,8 +3090,7 @@
 SourceLocation Loc,
 AlignmentSource Source = AlignmentSource::Type,
 bool isNontemporal = false) {
-return EmitLoadOfScalar(Addr, Volatile, Ty, Loc,
-LValueBaseInfo(Source, false),
+return EmitLoadOfScalar(Addr, Volatile, Ty, Loc, LValueBaseInfo(Source),
 CGM.getTBAAAccessInfo(Ty), isNontemporal);
   }
 
@@ -3115,7 +3112,7 @@
  bool Volatile, QualType Ty,
  AlignmentSource Source = AlignmentSource::Type,
  bool isInit = false, bool isNontemporal = false) {
-EmitStoreOfScalar(Value, Addr, Volatile, Ty, LValueBaseInfo(Source, false),
+EmitStoreOfScalar(Value, Addr, Volatile, Ty, LValueBaseInfo(Source),
   CGM.getTBAAAccessInfo(Ty), isInit, isNontemporal);
   }
 
Index: cfe/trunk/lib/CodeGen/CGOpenMPRuntime.cpp
===
--- cfe/trunk/lib/CodeGen/CGOpenMPRuntime.cpp
+++ cfe/trunk/lib/CodeGen/CGOpenMPRuntime.cpp
@@ -993,7 +993,7 @@
   CGF.Builder.CreateElementBitCast(SharedLVal.getAddress(),
CGF.ConvertTypeForMem(SharedType)),
   SharedType, SharedAddresses[N].first.getBaseInfo(),
-  CGF.CGM.getTBAAAccessInfo(SharedType));
+  CGF.CGM.getTBAAInfoForSubobject(SharedAddresses[N].first, SharedType));
   if (CGF.getContext().getAsArrayType(PrivateVD->getType())) {
 emitAggregateInitialization(CGF, N, PrivateAddr, SharedLVal, DRD);
   } else if (DRD && (DRD->getInitializer() || !PrivateVD->hasInit())) {
@@ -1046,7 +1046,7 @@
   CGF.Builder.CreateElementBitCast(BaseLV.getAddress(),
CGF.ConvertTypeForMem(ElTy)),
   BaseLV.getType(), BaseLV.getBaseInfo(),
-  CGF.CGM.getTBAAAccessInfo(BaseLV.getType()));
+  CGF.CGM.getTBAAInfoForSubobject(BaseLV, BaseLV.getType()));
 }
 
 static Address castToBase(CodeGenFunction &CGF, QualType BaseTy, QualType ElTy,
@@ -4084,9 +4084,8 @@
 SharedRefLValue = CGF.MakeAddrLValue(
 Address(SharedRefLValue.getPointer(), C.getDeclAlign(OriginalVD)),
 SharedRefLValue.getType(),
-LValueBaseInfo(AlignmentSource::Decl,
-   SharedRefLValue.getBaseInfo().getMayAlias()),
-CGF.CGM.getTBAAAccessInfo(SharedRefLValue.getType()));
+LValueBaseInfo(AlignmentSource::Decl),
+SharedRefLValue.getTBAAInfo());
 QualType Type = OriginalVD->getType();
 if (Type->isArrayType()) {
   // Initialize firstprivate array.
Index: cfe/trunk/lib/CodeGen/CodeGenTBAA.cpp
===
--- cfe/trunk/lib/CodeGen/CodeGenTBAA.cpp
+++ cfe/trunk/lib/CodeGen/CodeGenTBAA.cpp
@@ -88,6 +88,25 @@
   return false;
 }
 
+/// Check if the given type is a valid base type to be used in access tags.
+static bool isValidBaseType(QualType QTy) {
+  if (QTy->isReferenceType())
+return false;
+

[PATCH] D39008: [CodeGen] Propagate may-alias'ness of lvalues with TBAA info

2017-10-30 Thread John McCall via Phabricator via cfe-commits 
rjmccall accepted this revision.
rjmccall added a comment.
This revision is now accepted and ready to land.

LGTM.


https://reviews.llvm.org/D39008



___
cfe-commits mailing list
cfe-commits@lists.llvm.org
http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[PATCH] D39008: [CodeGen] Propagate may-alias'ness of lvalues with TBAA info

2017-10-30 Thread Ivan Kosarev via Phabricator via cfe-commits 
kosarev updated this revision to Diff 120828.
kosarev added a comment.

- Fixed comparing and hashing of TBAA access descriptors.
- Rebased on top of https://reviews.llvm.org/D39177.

Thanks John!


https://reviews.llvm.org/D39008

Files:
  lib/CodeGen/CGExpr.cpp
  lib/CodeGen/CGObjCRuntime.cpp
  lib/CodeGen/CGOpenMPRuntime.cpp
  lib/CodeGen/CGValue.h
  lib/CodeGen/CodeGenFunction.cpp
  lib/CodeGen/CodeGenFunction.h
  lib/CodeGen/CodeGenModule.cpp
  lib/CodeGen/CodeGenModule.h
  lib/CodeGen/CodeGenTBAA.cpp
  lib/CodeGen/CodeGenTBAA.h

Index: lib/CodeGen/CodeGenTBAA.h
===
--- lib/CodeGen/CodeGenTBAA.h
+++ lib/CodeGen/CodeGenTBAA.h
@@ -32,11 +32,22 @@
 namespace CodeGen {
 class CGRecordLayout;
 
+// TBAAAccessKind - A kind of TBAA memory access descriptor.
+enum class TBAAAccessKind : unsigned {
+  Ordinary,
+  MayAlias,
+};
+
 // TBAAAccessInfo - Describes a memory access in terms of TBAA.
 struct TBAAAccessInfo {
+  TBAAAccessInfo(TBAAAccessKind Kind, llvm::MDNode *BaseType,
+ llvm::MDNode *AccessType, uint64_t Offset)
+: Kind(Kind), BaseType(BaseType), AccessType(AccessType), Offset(Offset)
+  {}
+
   TBAAAccessInfo(llvm::MDNode *BaseType, llvm::MDNode *AccessType,
  uint64_t Offset)
-: BaseType(BaseType), AccessType(AccessType), Offset(Offset)
+: TBAAAccessInfo(TBAAAccessKind::Ordinary, BaseType, AccessType, Offset)
   {}
 
   explicit TBAAAccessInfo(llvm::MDNode *AccessType)
@@ -47,12 +58,31 @@
 : TBAAAccessInfo(/* AccessType= */ nullptr)
   {}
 
+  static TBAAAccessInfo getMayAliasInfo() {
+return TBAAAccessInfo(TBAAAccessKind::MayAlias, /* BaseType= */ nullptr,
+  /* AccessType= */ nullptr, /* Offset= */ 0);
+  }
+
+  bool isMayAlias() const { return Kind == TBAAAccessKind::MayAlias; }
+
   bool operator==(const TBAAAccessInfo &Other) const {
-return BaseType == Other.BaseType &&
+return Kind == Other.Kind &&
+   BaseType == Other.BaseType &&
AccessType == Other.AccessType &&
Offset == Other.Offset;
   }
 
+  bool operator!=(const TBAAAccessInfo &Other) const {
+return !(*this == Other);
+  }
+
+  explicit operator bool() const {
+return *this != TBAAAccessInfo();
+  }
+
+  /// Kind - The kind of the access descriptor.
+  TBAAAccessKind Kind;
+
   /// BaseType - The base/leading access type. May be null if this access
   /// descriptor represents an access that is not considered to be an access
   /// to an aggregate or union member.
@@ -139,14 +169,15 @@
   /// getAccessTagInfo - Get TBAA tag for a given memory access.
   llvm::MDNode *getAccessTagInfo(TBAAAccessInfo Info);
 
-  /// getMayAliasAccessInfo - Get TBAA information that represents may-alias
-  /// accesses.
-  TBAAAccessInfo getMayAliasAccessInfo();
-
   /// mergeTBAAInfoForCast - Get merged TBAA information for the purpose of
   /// type casts.
   TBAAAccessInfo mergeTBAAInfoForCast(TBAAAccessInfo SourceInfo,
   TBAAAccessInfo TargetInfo);
+
+  /// mergeTBAAInfoForConditionalOperator - Get merged TBAA information for the
+  /// purpose of conditional operator.
+  TBAAAccessInfo mergeTBAAInfoForConditionalOperator(TBAAAccessInfo InfoA,
+ TBAAAccessInfo InfoB);
 };
 
 }  // end namespace CodeGen
@@ -156,30 +187,34 @@
 
 template<> struct DenseMapInfo {
   static clang::CodeGen::TBAAAccessInfo getEmptyKey() {
+unsigned UnsignedKey = DenseMapInfo::getEmptyKey();
 return clang::CodeGen::TBAAAccessInfo(
+  static_cast(UnsignedKey),
   DenseMapInfo::getEmptyKey(),
   DenseMapInfo::getEmptyKey(),
   DenseMapInfo::getEmptyKey());
   }
 
   static clang::CodeGen::TBAAAccessInfo getTombstoneKey() {
+unsigned UnsignedKey = DenseMapInfo::getTombstoneKey();
 return clang::CodeGen::TBAAAccessInfo(
+  static_cast(UnsignedKey),
   DenseMapInfo::getTombstoneKey(),
   DenseMapInfo::getTombstoneKey(),
   DenseMapInfo::getTombstoneKey());
   }
 
   static unsigned getHashValue(const clang::CodeGen::TBAAAccessInfo &Val) {
-return DenseMapInfo::getHashValue(Val.BaseType) ^
+auto KindValue = static_cast(Val.Kind);
+return DenseMapInfo::getHashValue(KindValue) ^
+   DenseMapInfo::getHashValue(Val.BaseType) ^
DenseMapInfo::getHashValue(Val.AccessType) ^
DenseMapInfo::getHashValue(Val.Offset);
   }
 
   static bool isEqual(const clang::CodeGen::TBAAAccessInfo &LHS,
   const clang::CodeGen::TBAAAccessInfo &RHS) {
-return LHS.BaseType == RHS.BaseType &&
-   LHS.AccessType == RHS.AccessType &&
-   LHS.Offset == RHS.Offset;
+return LHS == RHS;
   }
 };
 
Index: lib/CodeGen/CodeGenTBAA.cpp
===
--- lib/CodeGen/CodeGenTBAA.cpp
+++ lib/CodeGen/CodeGenTBAA.cpp
@@ -88,6 +88,25 @@
   return false;
 }
 
+///

[PATCH] D39008: [CodeGen] Propagate may-alias'ness of lvalues with TBAA info

2017-10-29 Thread John McCall via Phabricator via cfe-commits 
rjmccall added a comment.

Looks good, but you missed updating equality/hashing for the new Kind field.




Comment at: lib/CodeGen/CodeGenTBAA.h:71
AccessType == Other.AccessType &&
Offset == Other.Offset;
   }

This needs to factor in the Kind.



Comment at: lib/CodeGen/CodeGenTBAA.h:205
DenseMapInfo::getHashValue(Val.AccessType) ^
DenseMapInfo::getHashValue(Val.Offset);
   }

This needs to factor in the Kind.


https://reviews.llvm.org/D39008



___
cfe-commits mailing list
cfe-commits@lists.llvm.org
http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[PATCH] D39008: [CodeGen] Propagate may-alias'ness of lvalues with TBAA info

2017-10-27 Thread Ivan Kosarev via Phabricator via cfe-commits 
kosarev updated this revision to Diff 120675.
kosarev added a comment.

Reworked to distinct may-alias accesses from ordinary ones with an explicit 
'kind' field.


https://reviews.llvm.org/D39008

Files:
  lib/CodeGen/CGExpr.cpp
  lib/CodeGen/CGObjCRuntime.cpp
  lib/CodeGen/CGOpenMPRuntime.cpp
  lib/CodeGen/CGValue.h
  lib/CodeGen/CodeGenFunction.cpp
  lib/CodeGen/CodeGenFunction.h
  lib/CodeGen/CodeGenModule.cpp
  lib/CodeGen/CodeGenModule.h
  lib/CodeGen/CodeGenTBAA.cpp
  lib/CodeGen/CodeGenTBAA.h

Index: lib/CodeGen/CodeGenTBAA.h
===
--- lib/CodeGen/CodeGenTBAA.h
+++ lib/CodeGen/CodeGenTBAA.h
@@ -32,11 +32,22 @@
 namespace CodeGen {
 class CGRecordLayout;
 
+// TBAAAccessKind - A kind of TBAA memory access descriptor.
+enum class TBAAAccessKind {
+  Ordinary,
+  MayAlias,
+};
+
 // TBAAAccessInfo - Describes a memory access in terms of TBAA.
 struct TBAAAccessInfo {
+  TBAAAccessInfo(TBAAAccessKind Kind, llvm::MDNode *BaseType,
+ llvm::MDNode *AccessType, uint64_t Offset)
+: Kind(Kind), BaseType(BaseType), AccessType(AccessType), Offset(Offset)
+  {}
+
   TBAAAccessInfo(llvm::MDNode *BaseType, llvm::MDNode *AccessType,
  uint64_t Offset)
-: BaseType(BaseType), AccessType(AccessType), Offset(Offset)
+: TBAAAccessInfo(TBAAAccessKind::Ordinary, BaseType, AccessType, Offset)
   {}
 
   explicit TBAAAccessInfo(llvm::MDNode *AccessType)
@@ -47,12 +58,30 @@
 : TBAAAccessInfo(/* AccessType= */ nullptr)
   {}
 
+  static TBAAAccessInfo getMayAliasInfo() {
+return TBAAAccessInfo(TBAAAccessKind::MayAlias, /* BaseType= */ nullptr,
+  /* AccessType= */ nullptr, /* Offset= */ 0);
+  }
+
+  bool isMayAlias() const { return Kind == TBAAAccessKind::MayAlias; }
+
   bool operator==(const TBAAAccessInfo &Other) const {
 return BaseType == Other.BaseType &&
AccessType == Other.AccessType &&
Offset == Other.Offset;
   }
 
+  bool operator!=(const TBAAAccessInfo &Other) const {
+return !(*this == Other);
+  }
+
+  explicit operator bool() const {
+return *this != TBAAAccessInfo();
+  }
+
+  /// Kind - The kind of the access descriptor.
+  TBAAAccessKind Kind;
+
   /// BaseType - The base/leading access type. May be null if this access
   /// descriptor represents an access that is not considered to be an access
   /// to an aggregate or union member.
@@ -139,14 +168,15 @@
   /// getAccessTagInfo - Get TBAA tag for a given memory access.
   llvm::MDNode *getAccessTagInfo(TBAAAccessInfo Info);
 
-  /// getMayAliasAccessInfo - Get TBAA information that represents may-alias
-  /// accesses.
-  TBAAAccessInfo getMayAliasAccessInfo();
-
   /// mergeTBAAInfoForCast - Get merged TBAA information for the purpose of
   /// type casts.
   TBAAAccessInfo mergeTBAAInfoForCast(TBAAAccessInfo SourceInfo,
   TBAAAccessInfo TargetInfo);
+
+  /// mergeTBAAInfoForConditionalOperator - Get merged TBAA information for the
+  /// purpose of conditional operator.
+  TBAAAccessInfo mergeTBAAInfoForConditionalOperator(TBAAAccessInfo InfoA,
+ TBAAAccessInfo InfoB);
 };
 
 }  // end namespace CodeGen
@@ -177,9 +207,7 @@
 
   static bool isEqual(const clang::CodeGen::TBAAAccessInfo &LHS,
   const clang::CodeGen::TBAAAccessInfo &RHS) {
-return LHS.BaseType == RHS.BaseType &&
-   LHS.AccessType == RHS.AccessType &&
-   LHS.Offset == RHS.Offset;
+return LHS == RHS;
   }
 };
 
Index: lib/CodeGen/CodeGenTBAA.cpp
===
--- lib/CodeGen/CodeGenTBAA.cpp
+++ lib/CodeGen/CodeGenTBAA.cpp
@@ -88,6 +88,25 @@
   return false;
 }
 
+/// Check if the given type is a valid base type to be used in access tags.
+static bool isValidBaseType(QualType QTy) {
+  if (QTy->isReferenceType())
+return false;
+  if (const RecordType *TTy = QTy->getAs()) {
+const RecordDecl *RD = TTy->getDecl()->getDefinition();
+// Incomplete types are not valid base access types.
+if (!RD)
+  return false;
+if (RD->hasFlexibleArrayMember())
+  return false;
+// RD can be struct, union, class, interface or enum.
+// For now, we only handle struct and class.
+if (RD->isStruct() || RD->isClass())
+  return true;
+  }
+  return false;
+}
+
 llvm::MDNode *CodeGenTBAA::getTypeInfo(QualType QTy) {
   // At -O0 or relaxed aliasing, TBAA is not emitted for regular types.
   if (CodeGenOpts.OptimizationLevel == 0 || CodeGenOpts.RelaxedAliasing)
@@ -98,8 +117,16 @@
   if (TypeHasMayAlias(QTy))
 return getChar();
 
-  const Type *Ty = Context.getCanonicalType(QTy).getTypePtr();
+  // We need this function to not fall back to returning the "omnipotent char"
+  // type node for aggregate and union types. Otherwise, any dereference of an
+  // aggregate will result into the may-alias access descripto

[PATCH] D39008: [CodeGen] Propagate may-alias'ness of lvalues with TBAA info

2017-10-26 Thread John McCall via Phabricator via cfe-commits 
rjmccall added a comment.

Sure, that makes sense to me.

John.


Repository:
  rL LLVM

https://reviews.llvm.org/D39008



___
cfe-commits mailing list
cfe-commits@lists.llvm.org
http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[PATCH] D39008: [CodeGen] Propagate may-alias'ness of lvalues with TBAA info

2017-10-26 Thread Ivan Kosarev via Phabricator via cfe-commits 
kosarev added a comment.

Yes, I don't like it too when it comes to comparing pointers to metadata nodes 
in an attempt to figure out what kind of access we are dealing with.

What concerns me is that there may be other kinds of TBAA descriptors that are 
neither ordinary nor may-alias ones. For example, at some point we will need to 
distinct TBAA descriptors for accesses to direct and indirect union members, 
because they require special processing.

What if we replace the may-alias flag with an enumeration? Something like this:

  enum class TBAAAccessKind {
Ordinary,
MayAlias,
  };


Repository:
  rL LLVM

https://reviews.llvm.org/D39008



___
cfe-commits mailing list
cfe-commits@lists.llvm.org
http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[PATCH] D39008: [CodeGen] Propagate may-alias'ness of lvalues with TBAA info

2017-10-26 Thread Ivan Kosarev via Phabricator via cfe-commits 
kosarev added a comment.

I suspect this is supposed to be in this diff:

In https://reviews.llvm.org/D38796#906887, @rjmccall wrote:

> I think probably the best solution is to track may-alias-ness explicitly in 
> the TBAAAccessInfo instead of relying in the frontend on being able to 
> distinguish things in the LLVM metadata.



Repository:
  rL LLVM

https://reviews.llvm.org/D39008



___
cfe-commits mailing list
cfe-commits@lists.llvm.org
http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[PATCH] D39008: [CodeGen] Propagate may-alias'ness of lvalues with TBAA info

2017-10-25 Thread Ivan Kosarev via Phabricator via cfe-commits 
kosarev added a comment.

Now that https://reviews.llvm.org/D38796 is comitted and added the 
tbaa-cast.cpp test case to the mainline, we fail on it with this patch applied. 
The reason is that we have no special TBAA type node for may-alias accesses, so 
everything that ever been a potential access to a character type turns into a 
may-alias access and propagates as such.

The test case reads:

  struct V {
unsigned n;
  };
  
  struct S {
char bytes[4];
  };
  
  void foo(S *p) {
((V*)p->bytes)->n = 5;
  }

Here, p->bytes decays to a pointer to char, meaning the pointee object is 
considered may-alias and so it is after the explicit cast.

This arises an interesting question: should we introduce a special 
representation for may-alias accesses to distinct them from character-typed 
accesses? Or, maybe explicit casts should not derive their may-alias'ness from 
their source operands? Or, maybe we want to consider all explicit casts of the 
form ##(T*)E## where ##T*## and ##typeof(E)## point to different types as 
pointers to may-alias objects?


Repository:
  rL LLVM

https://reviews.llvm.org/D39008



___
cfe-commits mailing list
cfe-commits@lists.llvm.org
http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[PATCH] D39008: [CodeGen] Propagate may-alias'ness of lvalues with TBAA info

2017-10-23 Thread John McCall via Phabricator via cfe-commits 
rjmccall accepted this revision.
rjmccall added a comment.
This revision is now accepted and ready to land.

Well, I've been agreeing so far that it makes sense to propagate TBAA 
information separately from LValueBaseInfo, and this seems like a logical part 
of that, so okay.


Repository:
  rL LLVM

https://reviews.llvm.org/D39008



___
cfe-commits mailing list
cfe-commits@lists.llvm.org
http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

[PATCH] D39008: [CodeGen] Propagate may-alias'ness of lvalues with TBAA info

2017-10-17 Thread Ivan Kosarev via Phabricator via cfe-commits 
kosarev created this revision.
kosarev added a project: clang.

This patch fixes various places in clang to propagate may-alias TBAA access 
descriptors during construction of lvalues, thus eliminating the need for the 
LValueBaseInfo::MayAlias flag.

This is part of https://reviews.llvm.org/D38126 reworked to be a separate patch 
to simplify review.


Repository:
  rL LLVM

https://reviews.llvm.org/D39008

Files:
  lib/CodeGen/CGExpr.cpp
  lib/CodeGen/CGObjCRuntime.cpp
  lib/CodeGen/CGOpenMPRuntime.cpp
  lib/CodeGen/CGValue.h
  lib/CodeGen/CodeGenFunction.cpp
  lib/CodeGen/CodeGenFunction.h
  lib/CodeGen/CodeGenModule.cpp
  lib/CodeGen/CodeGenModule.h
  lib/CodeGen/CodeGenTBAA.cpp
  lib/CodeGen/CodeGenTBAA.h

Index: lib/CodeGen/CodeGenTBAA.h
===
--- lib/CodeGen/CodeGenTBAA.h
+++ lib/CodeGen/CodeGenTBAA.h
@@ -53,6 +53,14 @@
Offset == Other.Offset;
   }
 
+  bool operator!=(const TBAAAccessInfo &Other) const {
+return !(*this == Other);
+  }
+
+  explicit operator bool() const {
+return *this != TBAAAccessInfo();
+  }
+
   /// BaseType - The base/leading access type. May be null if this access
   /// descriptor represents an access that is not considered to be an access
   /// to an aggregate or union member.
@@ -143,10 +151,18 @@
   /// accesses.
   TBAAAccessInfo getMayAliasAccessInfo();
 
+  /// isMayAliasAccessInfo - Test for the may-alias TBAA access descriptor.
+  bool isMayAliasAccessInfo(TBAAAccessInfo Info);
+
   /// mergeTBAAInfoForCast - Get merged TBAA information for the purpose of
   /// type casts.
   TBAAAccessInfo mergeTBAAInfoForCast(TBAAAccessInfo SourceInfo,
   TBAAAccessInfo TargetInfo);
+
+  /// mergeTBAAInfoForConditionalOperator - Get merged TBAA information for the
+  /// purpose of conditional operator.
+  TBAAAccessInfo mergeTBAAInfoForConditionalOperator(TBAAAccessInfo InfoA,
+ TBAAAccessInfo InfoB);
 };
 
 }  // end namespace CodeGen
@@ -177,9 +193,7 @@
 
   static bool isEqual(const clang::CodeGen::TBAAAccessInfo &LHS,
   const clang::CodeGen::TBAAAccessInfo &RHS) {
-return LHS.BaseType == RHS.BaseType &&
-   LHS.AccessType == RHS.AccessType &&
-   LHS.Offset == RHS.Offset;
+return LHS == RHS;
   }
 };
 
Index: lib/CodeGen/CodeGenTBAA.cpp
===
--- lib/CodeGen/CodeGenTBAA.cpp
+++ lib/CodeGen/CodeGenTBAA.cpp
@@ -88,6 +88,25 @@
   return false;
 }
 
+/// Check if the given type is a valid base type to be used in access tags.
+static bool isValidBaseType(QualType QTy) {
+  if (QTy->isReferenceType())
+return false;
+  if (const RecordType *TTy = QTy->getAs()) {
+const RecordDecl *RD = TTy->getDecl()->getDefinition();
+// Incomplete types are not valid base access types.
+if (!RD)
+  return false;
+if (RD->hasFlexibleArrayMember())
+  return false;
+// RD can be struct, union, class, interface or enum.
+// For now, we only handle struct and class.
+if (RD->isStruct() || RD->isClass())
+  return true;
+  }
+  return false;
+}
+
 llvm::MDNode *CodeGenTBAA::getTypeInfo(QualType QTy) {
   // At -O0 or relaxed aliasing, TBAA is not emitted for regular types.
   if (CodeGenOpts.OptimizationLevel == 0 || CodeGenOpts.RelaxedAliasing)
@@ -98,8 +117,16 @@
   if (TypeHasMayAlias(QTy))
 return getChar();
 
-  const Type *Ty = Context.getCanonicalType(QTy).getTypePtr();
+  // We need this function to not fall back to returning the "omnipotent char"
+  // type node for aggregate and union types. Otherwise, any dereference of an
+  // aggregate will result into the may-alias access descriptor, meaning all
+  // subsequent accesses to direct and indirect members of that aggregate will
+  // be considered may-alias too.
+  // TODO: Combine getTypeInfo() and getBaseTypeInfo() into a single function.
+  if (isValidBaseType(QTy))
+return getBaseTypeInfo(QTy);
 
+  const Type *Ty = Context.getCanonicalType(QTy).getTypePtr();
   if (llvm::MDNode *N = MetadataCache[Ty])
 return N;
 
@@ -232,20 +259,6 @@
   return StructMetadataCache[Ty] = nullptr;
 }
 
-/// Check if the given type is a valid base type to be used in access tags.
-static bool isValidBaseType(QualType QTy) {
-  if (const RecordType *TTy = QTy->getAs()) {
-const RecordDecl *RD = TTy->getDecl()->getDefinition();
-if (RD->hasFlexibleArrayMember())
-  return false;
-// RD can be struct, union, class, interface or enum.
-// For now, we only handle struct and class.
-if (RD->isStruct() || RD->isClass())
-  return true;
-  }
-  return false;
-}
-
 llvm::MDNode *CodeGenTBAA::getBaseTypeInfo(QualType QTy) {
   if (!isValidBaseType(QTy))
 return nullptr;
@@ -317,3 +330,26 @@
 return MayAliasInfo;
   return TargetInfo;
 }
+
+bool CodeGenTBAA::isMayAliasAccessInfo(TBAAAccessInfo Info) {
+