[AIX] "aligned" attribute does not decrease alignment

[stevewan]

Summary

The "aligned" attribute can only increase the alignment of a struct, or struct member, unless it's used together with the "packed" attribute, or used as a part of a typedef, in which case, the "aligned" attribute can both increase and decrease alignment.

That said, we expect:

1. "aligned" attribute alone: does not interfere with the alignment upgrade instrumented by the AIX "power" alignment rule,
2. "aligned" attribute + typedef: overrides any computed alignment,
3. "aligned" attribute + "packed" attribute: overrides any computed alignment.

The old implementation achieved 2 and 3, but didn't get 1 right, in that any field marked attribute "aligned" would not go through the alignment upgrade.

[stevewan]

Attr 'packed' is already taken into account in ABIAlign/PreferredAlign

[stevewan]

Fix incomplete diff, please discard last update.

[sfertile]

clang/test/Layout/aix-alignof-align-and-pack-attr.cpp

11

Minor nit: I think the other test can live in this file, highlighting the difference between the 2 cases is nice. Also I think we should add a typedef test in here as well.

[stevewan]

Merge tests into one file

[stevewan]

clang/test/Layout/aix-alignof-align-and-pack-attr.cpp

11

Merged the tests as suggested. We have the typedef coverage in aix-power-alignment-typedef.cpp and aix-power-alignment-typedef2.cpp, not sure if want to merge those as well.

[sfertile]

Thanks Steven, LGTM.

clang/test/Layout/aix-alignof-align-and-pack-attr.cpp

11

No need to merge those as well.

[stevewan]

Fix the same problem in field layout.

[stevewan]

Add test cases

[stevewan]

The query portion has been split out as https://reviews.llvm.org/D107598, which needs to be cleaned out from this patch. The record layout part also needs update as we uncover more problems with the current implementation.

[stevewan]

Rebase to latest main

[stevewan]

Fields marked attribute "aligned" and "packed" don't need to go through alignment upgrade

[rjmccall]

clang/lib/AST/RecordLayoutBuilder.cpp

1975

Okay, so first off, the comment and variable names here make this sound very general when in fact this computation is only relevant to the AIX alignment upgrade logic. Also, please do not introduce new variables with broad scope named things like Ty that are actually referring to a very specific type and not, say, the unadulterated type of the field.

It seems to me that the right way to think about this is that, while the AIX power alignment upgrade considers whether field type alignment is "required", it uses a different condition than the standard rule when making that decision. It's important to understand what that rule is exactly, and we can't see that from the current test cases. In particular, attributes on fields that define structs inline actually end up applying to both the field and the struct, which confounds unrelated issues. Consider:

struct __attribute__((packed, aligned(2))) SS {
  double d;
};

struct S {
  // Neither the field nor the struct are packed, but the field type is.
  // Do we apply the alignment upgrade to S or not?
  struct SS s;
};

Regardless, I don't think this check for a typedef works; it's bypassing quite a bit of recursive logic for computing whether type alignment is required. For example, you could have an explicitly aligned typedef of an array type, and you'll lose that typedef here.

[stevewan]

Address comments about the check

[stevewan]

clang/lib/AST/RecordLayoutBuilder.cpp

1975

Thanks for the review.

the comment and variable names here make this sound very general when in fact this computation is only relevant to the AIX alignment upgrade logic.

Moved the variable declarations back to the AIX alignment upgrade logic.

It's important to understand what that rule is exactly, and we can't see that from the current test cases.

Updated the test cases accordingly.

For example, you could have an explicitly aligned typedef of an array type, and you'll lose that typedef here.

Updated the check to examine the immediate type rather than the base element type, this should take care of the array-type considerations.

[stevewan]

De-Morgan-ize if condition for readability

[stevewan]

Fix typo

[rjmccall]

clang/lib/AST/RecordLayoutBuilder.cpp

1975

No, I'm not sure that's quite correct, either, because you might have an array of an explicitly aligned typedef. You might need to do a recursive examination of the type the same way that getTypeInfo would, except I guess not recursing into records.

I assume you verified that the behavior in your new test cases matches the behavior of some existing AIX compiler? For our general edification, what compiler(s) are you testing against?

I've found that extracting very complex conditions into a function (perhaps a lambda if it's inconvenient to have it separately-declared) can be useful.

[stevewan]

Add recursive check for typedef

[stevewan]

clang/lib/AST/RecordLayoutBuilder.cpp

1975

Added a lambda function that mimics getTypeInfo to do the recursive check. If this looks about right in direction, I'm also going to memorize known types' typedef-ness in a map for faster lookup.

Yes, the behaviour was verified, and matches the behaviour of XL 16.1 on AIX.

[stevewan]

Avoid unannotated fall-through between cases

[rjmccall]

clang/lib/AST/RecordLayoutBuilder.cpp

1993

Hah. The knot-tying here is really cute, but I think either just make it a static function somewhere in the file, or make it iterative instead of recursive.

...actually, I think it would be better to just make the computation in getTypeInfo preserve more information. Make TypeInfo carry a three-valued enum instead of an AlignIsRequired flag:

enum class AlignRequirement {
  /// The alignment was not explicit in code.
  None,

  /// The alignment comes from an alignment attribute on a typedef.
  RequiredByTypedef,

  /// The alignment comes from an alignment attribute on a record type.
  RequiredByRecord,
};

You can add a method on TypeInfo to ask if the alignment is required for any reason and make all the existing clients use that instead.

[stevewan]

Make TypeInfo carry more information about "aligned" attribute

[stevewan]

clang/lib/AST/RecordLayoutBuilder.cpp

1993

Good idea. I had thought about a similar approach but was afraid that the change may get too pervasive. I think it turned out fine. I'm now debating whether I should split this whole bool-to-enum change into a separate patch, any preference?

[rjmccall]

Thanks, style suggestion aside, this looks great. Would you mind doing the TypeInfo change in a separate patch? The functional change for AIX can be a really small improvement on top of that.

clang/include/clang/AST/ASTContext.h

167

We've been calling things like this FooKind for a while. FooType is pretty problematic in a compiler where we have a lot of type representations. I think there are a few grandfathered exceptions, but still, let's call it AlignRequirementKind.

[stevewan]

Cleanup the condition check

[stevewan]

Fix typo

[stevewan]

Fix missing "&&"

[rjmccall]

Please add me to the review for the other patch and I'll approve it pretty quickly, and then we can get back to this one.

[stevewan]

In D107394#2970326, @rjmccall wrote:

Please add me to the review for the other patch and I'll approve it pretty quickly, and then we can get back to this one.

Sorry for the delay. Posted https://reviews.llvm.org/D108858, once that's in I'll rebase.

[stevewan]

Adapt to new TypeInfo design

[rjmccall]

Thanks, this looks a lot cleaner. Minor requests only.

[rjmccall]

clang/lib/AST/RecordLayoutBuilder.cpp

1975

Somehow my requests didn't make it through. Please name this lambda something AIX-specific, and please clarify in a comment that we can ignore enum alignment sources because the alignment upgrade only applies to floating-point types.

[stevewan]

Rename lambda and add comments

[rjmccall]

Thanks, LGTM!

clang/include/clang/AST/ASTContext.h

 class Context;
 
 } // namespace interp
 
 namespace serialization {
 template <class> class AbstractTypeReader;
 } // namespace serialization
 
+enum class AlignRequirementType {
+  /// The alignment was not explicit in code.
+  None,
+
+  /// The alignment comes from an alignment attribute on a typedef.
+  RequiredByTypedef,
+
+  /// The alignment comes from an alignment attribute on a record type.
+  RequiredByRecord,
+};
+
 struct TypeInfo {
   uint64_t Width = 0;
   unsigned Align = 0;
-  bool AlignIsRequired : 1;
+  AlignRequirementType AlignRequirement;
 
-  TypeInfo() : AlignIsRequired(false) {}
-  TypeInfo(uint64_t Width, unsigned Align, bool AlignIsRequired)
-      : Width(Width), Align(Align), AlignIsRequired(AlignIsRequired) {}
+  TypeInfo() : AlignRequirement(AlignRequirementType::None) {}
+  TypeInfo(uint64_t Width, unsigned Align,
+           AlignRequirementType AlignRequirement)
+      : Width(Width), Align(Align), AlignRequirement(AlignRequirement) {}
+  bool isAlignRequired() {
+    return AlignRequirement != AlignRequirementType::None;
+  }
 };
 
 struct TypeInfoChars {
   CharUnits Width;
   CharUnits Align;
-  bool AlignIsRequired : 1;
+  AlignRequirementType AlignRequirement;
 
-  TypeInfoChars() : AlignIsRequired(false) {}
-  TypeInfoChars(CharUnits Width, CharUnits Align, bool AlignIsRequired)
-      : Width(Width), Align(Align), AlignIsRequired(AlignIsRequired) {}
+  TypeInfoChars() : AlignRequirement(AlignRequirementType::None) {}
+  TypeInfoChars(CharUnits Width, CharUnits Align,
+                AlignRequirementType AlignRequirement)
+      : Width(Width), Align(Align), AlignRequirement(AlignRequirement) {}
+  bool isAlignRequired() {
+    return AlignRequirement != AlignRequirementType::None;
+  }
 };
 
 /// Holds long-lived AST nodes (such as types and decls) that can be
 /// referred to throughout the semantic analysis of a file.
 class ASTContext : public RefCountedBase<ASTContext> {
   friend class NestedNameSpecifier;
 
   mutable SmallVector<Type *, 0> Types;

clang/lib/AST/ASTContext.cpp

assert((Size == 0 || static_cast<uint64_t>(EltInfo.Width.getQuantity()) <=
          "Overflow in array type char size evaluation");
   uint64_t Width = EltInfo.Width.getQuantity() * Size;
   unsigned Align = EltInfo.Align.getQuantity();
   if (!Context.getTargetInfo().getCXXABI().isMicrosoft() ||
       Context.getTargetInfo().getPointerWidth(0) == 64)
     Width = llvm::alignTo(Width, Align);
   return TypeInfoChars(CharUnits::fromQuantity(Width),
                        CharUnits::fromQuantity(Align),
-                       EltInfo.AlignIsRequired);
+                       EltInfo.AlignRequirement);
 }
 
 TypeInfoChars ASTContext::getTypeInfoInChars(const Type *T) const {
   if (const auto *CAT = dyn_cast<ConstantArrayType>(T))
     return getConstantArrayInfoInChars(*this, CAT);
   TypeInfo Info = getTypeInfo(T);
   return TypeInfoChars(toCharUnitsFromBits(Info.Width),
-                       toCharUnitsFromBits(Info.Align),
-                       Info.AlignIsRequired);
+                       toCharUnitsFromBits(Info.Align), Info.AlignRequirement);
 }
 
 TypeInfoChars ASTContext::getTypeInfoInChars(QualType T) const {
   return getTypeInfoInChars(T.getTypePtr());
 }
 
 bool ASTContext::isAlignmentRequired(const Type *T) const {
-  return getTypeInfo(T).AlignIsRequired;
+  return getTypeInfo(T).AlignRequirement != AlignRequirementType::None;
 }
 
 bool ASTContext::isAlignmentRequired(QualType T) const {
   return isAlignmentRequired(T.getTypePtr());
 }
 
 unsigned ASTContext::getTypeAlignIfKnown(QualType T,
                                          bool NeedsPreferredAlignment) const {

 /// method does not work on incomplete types.
 ///
 /// FIXME: Pointers into different addr spaces could have different sizes and
 /// alignment requirements: getPointerInfo should take an AddrSpace, this
 /// should take a QualType, &c.
 TypeInfo ASTContext::getTypeInfoImpl(const Type *T) const {
   uint64_t Width = 0;
   unsigned Align = 8;
-  bool AlignIsRequired = false;
+  AlignRequirementType AlignRequirement = AlignRequirementType::None;
   unsigned AS = 0;
   switch (T->getTypeClass()) {
 #define TYPE(Class, Base)
 #define ABSTRACT_TYPE(Class, Base)
 #define NON_CANONICAL_TYPE(Class, Base)
 #define DEPENDENT_TYPE(Class, Base) case Type::Class:
 #define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(Class, Base)                       \
   case Type::Class:                                                            \
case Type::ConstantArray: {
     if (const auto *CAT = dyn_cast<ConstantArrayType>(T))
       Size = CAT->getSize().getZExtValue();
 
     TypeInfo EltInfo = getTypeInfo(cast<ArrayType>(T)->getElementType());
     assert((Size == 0 || EltInfo.Width <= (uint64_t)(-1) / Size) &&
            "Overflow in array type bit size evaluation");
     Width = EltInfo.Width * Size;
     Align = EltInfo.Align;
-    AlignIsRequired = EltInfo.AlignIsRequired;
+    AlignRequirement = EltInfo.AlignRequirement;
     if (!getTargetInfo().getCXXABI().isMicrosoft() ||
         getTargetInfo().getPointerWidth(0) == 64)
       Width = llvm::alignTo(Width, Align);
     break;
   }
 
   case Type::ExtVector:
   case Type::Vector: {
     const auto *VT = cast<VectorType>(T);
     TypeInfo EltInfo = getTypeInfo(VT->getElementType());
     Width = EltInfo.Width * VT->getNumElements();
     Align = Width;
     // If the alignment is not a power of 2, round up to the next power of 2.
     // This happens for non-power-of-2 length vectors.
-    if (Align & (Align-1)) {
+    if (Align & (Align - 1)) {
       Align = llvm::NextPowerOf2(Align);
       Width = llvm::alignTo(Width, Align);
     }
     // Adjust the alignment based on the target max.
     uint64_t TargetVectorAlign = Target->getMaxVectorAlign();
     if (TargetVectorAlign && TargetVectorAlign < Align)
       Align = TargetVectorAlign;
     if (VT->getVectorKind() == VectorType::SveFixedLengthDataVector)
case Type::Enum: {
     }
 
     if (const auto *ET = dyn_cast<EnumType>(TT)) {
       const EnumDecl *ED = ET->getDecl();
       TypeInfo Info =
           getTypeInfo(ED->getIntegerType()->getUnqualifiedDesugaredType());
       if (unsigned AttrAlign = ED->getMaxAlignment()) {
         Info.Align = AttrAlign;
-        Info.AlignIsRequired = true;
+        Info.AlignRequirement = AlignRequirementType::RequiredByRecord;
       }
       return Info;
     }
 
     const auto *RT = cast<RecordType>(TT);
     const RecordDecl *RD = RT->getDecl();
     const ASTRecordLayout &Layout = getASTRecordLayout(RD);
     Width = toBits(Layout.getSize());
     Align = toBits(Layout.getAlignment());
-    AlignIsRequired = RD->hasAttr<AlignedAttr>();
+    AlignRequirement = RD->hasAttr<AlignedAttr>()
+                           ? AlignRequirementType::RequiredByRecord
+                           : AlignRequirementType::None;
     break;
   }
 
   case Type::SubstTemplateTypeParm:
     return getTypeInfo(cast<SubstTemplateTypeParmType>(T)->
                        getReplacementType().getTypePtr());
 
   case Type::Auto:
#include "clang/Basic/RISCVVTypes.def"
   case Type::Typedef: {
     const TypedefNameDecl *Typedef = cast<TypedefType>(T)->getDecl();
     TypeInfo Info = getTypeInfo(Typedef->getUnderlyingType().getTypePtr());
     // If the typedef has an aligned attribute on it, it overrides any computed
     // alignment we have.  This violates the GCC documentation (which says that
     // attribute(aligned) can only round up) but matches its implementation.
     if (unsigned AttrAlign = Typedef->getMaxAlignment()) {
       Align = AttrAlign;
-      AlignIsRequired = true;
+      AlignRequirement = AlignRequirementType::RequiredByTypedef;
     } else {
       Align = Info.Align;
-      AlignIsRequired = Info.AlignIsRequired;
+      AlignRequirement = Info.AlignRequirement;
     }
     Width = Info.Width;
     break;
   }
 
   case Type::Elaborated:
     return getTypeInfo(cast<ElaboratedType>(T)->getNamedType().getTypePtr());
 
#include "clang/Basic/RISCVVTypes.def"
 
   case Type::Pipe:
     Width = Target->getPointerWidth(getTargetAddressSpace(LangAS::opencl_global));
     Align = Target->getPointerAlign(getTargetAddressSpace(LangAS::opencl_global));
     break;
   }
 
   assert(llvm::isPowerOf2_32(Align) && "Alignment must be power of 2");
-  return TypeInfo(Width, Align, AlignIsRequired);
+  return TypeInfo(Width, Align, AlignRequirement);
 }
 
 unsigned ASTContext::getTypeUnadjustedAlign(const Type *T) const {
   UnadjustedAlignMap::iterator I = MemoizedUnadjustedAlign.find(T);
   if (I != MemoizedUnadjustedAlign.end())
     return I->second;
 
   unsigned UnadjustedAlign;
unsigned ASTContext::getPreferredTypeAlign(const Type *T) const {
   if (!Target->allowsLargerPreferedTypeAlignment())
     return ABIAlign;
 
   if (const auto *RT = T->getAs<RecordType>()) {
     const RecordDecl *RD = RT->getDecl();
 
     // When used as part of a typedef, or together with a 'packed' attribute,
     // the 'aligned' attribute can be used to decrease alignment.
-    if ((TI.AlignIsRequired && T->getAs<TypedefType>() != nullptr) ||
+    if ((TI.isAlignRequired() && T->getAs<TypedefType>() != nullptr) ||
         RD->isInvalidDecl())
       return ABIAlign;
 
     unsigned PreferredAlign = static_cast<unsigned>(
         toBits(getASTRecordLayout(RD).PreferredAlignment));
     assert(PreferredAlign >= ABIAlign &&
            "PreferredAlign should be at least as large as ABIAlign.");
     return PreferredAlign;
   }
 
   // Double (and, for targets supporting AIX `power` alignment, long double) and
   // long long should be naturally aligned (despite requiring less alignment) if
   // possible.
   if (const auto *CT = T->getAs<ComplexType>())
     T = CT->getElementType().getTypePtr();
   if (const auto *ET = T->getAs<EnumType>())
     T = ET->getDecl()->getIntegerType().getTypePtr();
   if (T->isSpecificBuiltinType(BuiltinType::Double) ||
       T->isSpecificBuiltinType(BuiltinType::LongLong) ||
       T->isSpecificBuiltinType(BuiltinType::ULongLong) ||
       (T->isSpecificBuiltinType(BuiltinType::LongDouble) &&
        Target->defaultsToAIXPowerAlignment()))
     // Don't increase the alignment if an alignment attribute was specified on a
     // typedef declaration.
-    if (!TI.AlignIsRequired)
+    if (!TI.isAlignRequired())
       return std::max(ABIAlign, (unsigned)getTypeSize(T));
 
   return ABIAlign;
 }
 
 /// getTargetDefaultAlignForAttributeAligned - Return the default alignment
 /// for __attribute__((aligned)) on this target, to be used if no alignment
 /// value is specified.

clang/lib/AST/RecordLayoutBuilder.cpp

 }
 
 void ItaniumRecordLayoutBuilder::LayoutBitField(const FieldDecl *D) {
   bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
   uint64_t FieldSize = D->getBitWidthValue(Context);
   TypeInfo FieldInfo = Context.getTypeInfo(D->getType());
   uint64_t StorageUnitSize = FieldInfo.Width;
   unsigned FieldAlign = FieldInfo.Align;
-  bool AlignIsRequired = FieldInfo.AlignIsRequired;
+  bool AlignIsRequired = FieldInfo.isAlignRequired();
 
   // UnfilledBitsInLastUnit is the difference between the end of the
   // last allocated bitfield (i.e. the first bit offset available for
   // bitfields) and the end of the current data size in bits (i.e. the
   // first bit offset available for non-bitfields).  The current data
   // size in bits is always a multiple of the char size; additionally,
   // for ms_struct records it's also a multiple of the
   // LastBitfieldStorageUnitSize (if set).
void ItaniumRecordLayoutBuilder::LayoutField(const FieldDecl *D,
 
   uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastUnit;
   // Reset the unfilled bits.
   UnfilledBitsInLastUnit = 0;
   LastBitfieldStorageUnitSize = 0;
 
   bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
 
-  bool AlignIsRequired = false;
+  AlignRequirementType AlignRequirement = AlignRequirementType::None;
   CharUnits FieldSize;
   CharUnits FieldAlign;
   // The amount of this class's dsize occupied by the field.
   // This is equal to FieldSize unless we're permitted to pack
   // into the field's tail padding.
   CharUnits EffectiveFieldSize;
 
   auto setDeclInfo = [&](bool IsIncompleteArrayType) {
     auto TI = Context.getTypeInfoInChars(D->getType());
     FieldAlign = TI.Align;
     // Flexible array members don't have any size, but they have to be
     // aligned appropriately for their element type.
     EffectiveFieldSize = FieldSize =
         IsIncompleteArrayType ? CharUnits::Zero() : TI.Width;
-    AlignIsRequired = TI.AlignIsRequired;
+    AlignRequirement = TI.AlignRequirement;
   };
 
   if (D->getType()->isIncompleteArrayType()) {
     setDeclInfo(true /* IsIncompleteArrayType */);
   } else if (const ReferenceType *RT = D->getType()->getAs<ReferenceType>()) {
     unsigned AS = Context.getTargetAddressSpace(RT->getPointeeType());
     EffectiveFieldSize = FieldSize = Context.toCharUnitsFromBits(
         Context.getTargetInfo().getPointerWidth(AS));
if (IsMsStruct) {
         }
         if (TypeSize > FieldAlign &&
             llvm::isPowerOf2_64(TypeSize.getQuantity()))
           FieldAlign = TypeSize;
       }
     }
   }
 
+  // When used as part of a typedef, or together with a 'packed' attribute,
+  // the 'aligned' attribute can be used to decrease alignment. In that case,
+  // it overrides any computed alignment we have, and there is no need to
+  // upgrade the alignment.
+  auto alignedAttrCanDecreaseAlignment = [AlignRequirement, FieldPacked]() {
+    return AlignRequirement == AlignRequirementType::RequiredByTypedef ||
+           (AlignRequirement == AlignRequirementType::RequiredByRecord &&
+            FieldPacked);
+  };
+
   // The AIX `power` alignment rules apply the natural alignment of the
   // "first member" if it is of a floating-point data type (or is an aggregate
   // whose recursively "first" member or element is such a type). The alignment
   // associated with these types for subsequent members use an alignment value
   // where the floating-point data type is considered to have 4-byte alignment.
   //
   // For the purposes of the foregoing: vtable pointers, non-empty base classes,
   // and zero-width bit-fields count as prior members; members of empty class
   // types marked `no_unique_address` are not considered to be prior members.
   CharUnits PreferredAlign = FieldAlign;
-  if (DefaultsToAIXPowerAlignment && !AlignIsRequired &&
-      (FoundFirstNonOverlappingEmptyFieldForAIX || IsNaturalAlign)) {
+  if (DefaultsToAIXPowerAlignment &&
+      !alignedAttrCanDecreaseAlignment()(
+          FoundFirstNonOverlappingEmptyFieldForAIX || IsNaturalAlign)) {
     auto performBuiltinTypeAlignmentUpgrade = [&](const BuiltinType *BTy) {
       if (BTy->getKind() == BuiltinType::Double ||
           BTy->getKind() == BuiltinType::LongDouble) {
         assert(PreferredAlign == CharUnits::fromQuantity(4) &&
                "No need to upgrade the alignment value.");
         PreferredAlign = CharUnits::fromQuantity(8);
       }
     };
 
-    const Type *Ty = D->getType()->getBaseElementTypeUnsafe();
-    if (const ComplexType *CTy = Ty->getAs<ComplexType>()) {
-      performBuiltinTypeAlignmentUpgrade(CTy->getElementType()->castAs<BuiltinType>());
-    } else if (const BuiltinType *BTy = Ty->getAs<BuiltinType>()) {
+    const Type *BaseTy = D->getType()->getBaseElementTypeUnsafe();
+    if (const ComplexType *CTy = BaseTy->getAs<ComplexType>()) {
+      performBuiltinTypeAlignmentUpgrade(
+          CTy->getElementType()->castAs<BuiltinType>());
+    } else if (const BuiltinType *BTy = BaseTy->getAs<BuiltinType>()) {
       performBuiltinTypeAlignmentUpgrade(BTy);
-    } else if (const RecordType *RT = Ty->getAs<RecordType>()) {
+    } else if (const RecordType *RT = BaseTy->getAs<RecordType>()) {
       const RecordDecl *RD = RT->getDecl();
       assert(RD && "Expected non-null RecordDecl.");
       const ASTRecordLayout &FieldRecord = Context.getASTRecordLayout(RD);
       PreferredAlign = FieldRecord.getPreferredAlignment();
     }
   }
 
   // The align if the field is not packed. This is to check if the attribute

clang/lib/CodeGen/CGDebugInfo.cpp

 #include "llvm/Support/MD5.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/TimeProfiler.h"
 using namespace clang;
 using namespace clang::CodeGen;
 
 static uint32_t getTypeAlignIfRequired(const Type *Ty, const ASTContext &Ctx) {
   auto TI = Ctx.getTypeInfo(Ty);
-  return TI.AlignIsRequired ? TI.Align : 0;
+  return TI.isAlignRequired() ? TI.Align : 0;
 }
 
 static uint32_t getTypeAlignIfRequired(QualType Ty, const ASTContext &Ctx) {
   return getTypeAlignIfRequired(Ty.getTypePtr(), Ctx);
 }
 
 static uint32_t getDeclAlignIfRequired(const Decl *D, const ASTContext &Ctx) {
   return D->hasAttr<AlignedAttr>() ? D->getMaxAlignment() : 0;
for (const BlockLayoutChunk &Chunk : chunks) {
     }
 
     const VarDecl *variable = capture->getVariable();
     StringRef name = variable->getName();
 
     llvm::DIType *fieldType;
     if (capture->isByRef()) {
       TypeInfo PtrInfo = C.getTypeInfo(C.VoidPtrTy);
-      auto Align = PtrInfo.AlignIsRequired ? PtrInfo.Align : 0;
+      auto Align = PtrInfo.isAlignRequired() ? PtrInfo.Align : 0;
       // FIXME: This recomputes the layout of the BlockByRefWrapper.
       uint64_t xoffset;
       fieldType =
           EmitTypeForVarWithBlocksAttr(variable, &xoffset).BlockByRefWrapper;
       fieldType = DBuilder.createPointerType(fieldType, PtrInfo.Width);
       fieldType = DBuilder.createMemberType(tunit, name, tunit, line,
                                             PtrInfo.Width, Align, offsetInBits,
                                             llvm::DINode::FlagZero, fieldType);

clang/lib/CodeGen/MicrosoftCXXABI.cpp

case llvm::Triple::thumb:
     return RAA_Indirect;
 
   case llvm::Triple::x86: {
     // If the argument has *required* alignment greater than four bytes, pass
     // it indirectly. Prior to MSVC version 19.14, passing overaligned
     // arguments was not supported and resulted in a compiler error. In 19.14
     // and later versions, such arguments are now passed indirectly.
     TypeInfo Info = getContext().getTypeInfo(RD->getTypeForDecl());
-    if (Info.AlignIsRequired && Info.Align > 4)
+    if (Info.isAlignRequired() && Info.Align > 4)
       return RAA_Indirect;
 
     // If C++ prohibits us from making a copy, construct the arguments directly
     // into argument memory.
     return RAA_DirectInMemory;
   }
 
   case llvm::Triple::x86_64:

clang/lib/CodeGen/TargetInfo.cpp

if (shouldAggregateUseDirect(Ty, State, InReg, NeedsPadding)) {
         return ABIArgInfo::getDirectInReg(Result);
       else
         return ABIArgInfo::getDirect(Result);
     }
     llvm::IntegerType *PaddingType = NeedsPadding ? Int32 : nullptr;
 
     // Pass over-aligned aggregates on Windows indirectly. This behavior was
     // added in MSVC 2015.
-    if (IsWin32StructABI && TI.AlignIsRequired && TI.Align > 32)
+    if (IsWin32StructABI && TI.isAlignRequired() && TI.Align > 32)
       return getIndirectResult(Ty, /*ByVal=*/false, State);
 
     // Expand small (<= 128-bit) record types when we know that the stack layout
     // of those arguments will match the struct. This is important because the
     // LLVM backend isn't smart enough to remove byval, which inhibits many
     // optimizations.
     // Don't do this for the MCU if there are still free integer registers
     // (see X86_64 ABI for full explanation).
Address ARMABIInfo::EmitVAArg(CodeGenFunction &CGF, Address VAListAddr,
   } else if (getABIKind() == ARMABIInfo::AAPCS16_VFP) {
     // ARMv7k allows type alignment up to 16 bytes.
     TyAlignForABI = std::max(TyAlignForABI, CharUnits::fromQuantity(4));
     TyAlignForABI = std::min(TyAlignForABI, CharUnits::fromQuantity(16));
   } else {
     TyAlignForABI = CharUnits::fromQuantity(4);
   }
 
-  TypeInfoChars TyInfo(TySize, TyAlignForABI, false);
+  TypeInfoChars TyInfo(TySize, TyAlignForABI, AlignRequirementType::None);
   return emitVoidPtrVAArg(CGF, VAListAddr, Ty, IsIndirect, TyInfo,
                           SlotSize, /*AllowHigherAlign*/ true);
 }
 
 //===----------------------------------------------------------------------===//
 // NVPTX ABI Implementation
 //===----------------------------------------------------------------------===//
 

clang/test/Layout/aix-alignof-align-and-pack-attr.cpp

-// RUN: %clang_cc1 -triple powerpc-ibm-aix-xcoff -S -emit-llvm -x c++ < %s | \
-// RUN:   FileCheck %s
-
-// RUN: %clang_cc1 -triple powerpc64-ibm-aix-xcoff -S -emit-llvm -x c++ < %s | \
-// RUN:   FileCheck %s
-
-namespace test1 {
-struct __attribute__((__aligned__(2))) C {
-  double x;
-} c;
-
-// CHECK: @{{.*}}test1{{.*}}c{{.*}} = global %"struct.test1::C" zeroinitializer, align 8
-} // namespace test1
-
-namespace test2 {
-struct __attribute__((__aligned__(2), packed)) C {
-  double x;
-} c;
-
-// CHECK: @{{.*}}test2{{.*}}c{{.*}} = global %"struct.test2::C" zeroinitializer, align 2
-} // namespace test2
-
-namespace test3 {
-struct __attribute__((__aligned__(16))) C {
-  double x;
-} c;
-
-// CHECK: @{{.*}}test3{{.*}}c{{.*}} = global %"struct.test3::C" zeroinitializer, align 16
-} // namespace test3

clang/test/Layout/aix-power-alignment-typedef.cpp

 
 // CHECK:          0 | union test2::U
 // CHECK-NEXT:     0 |   test2::DblArr da
 // CHECK-NEXT:     0 |   char x
 // CHECK-NEXT:       | [sizeof=2, dsize=2, align=2, preferredalign=2,
 // CHECK-NEXT:       |  nvsize=2, nvalign=2, preferrednvalign=2]
 
 } // namespace test2
+
+namespace test3 {
+typedef double DblArr[] __attribute__((__aligned__(2)));
+
+union U {
+  DblArr da;
+  char x;
+};
+
+int x = sizeof(U);
+
+// CHECK:          0 | union test3::U
+// CHECK-NEXT:     0 |   test3::DblArr da
+// CHECK-NEXT:     0 |   char x
+// CHECK-NEXT:       | [sizeof=2, dsize=2, align=2, preferredalign=2,
+// CHECK-NEXT:       |  nvsize=2, nvalign=2, preferrednvalign=2]
+
+} // namespace test3
+
+namespace test4 {
+typedef double Dbl __attribute__((__aligned__(2)));
+
+union U {
+  Dbl DblArr[];
+  char x;
+};
+
+int x = sizeof(U);
+
+// CHECK:          0 | union test4::U
+// CHECK-NEXT:     0 |   test4::Dbl [] DblArr
+// CHECK-NEXT:     0 |   char x
+// CHECK-NEXT:       | [sizeof=2, dsize=2, align=2, preferredalign=2,
+// CHECK-NEXT:       |  nvsize=2, nvalign=2, preferrednvalign=2]
+
+} // namespace test4

clang/test/Layout/aix-type-align-and-pack-attr.cpp

+// RUN: %clang_cc1 -triple powerpc-ibm-aix-xcoff -S -emit-llvm -x c++ < %s | \
+// RUN:   FileCheck %s
+
+// RUN: %clang_cc1 -triple powerpc64-ibm-aix-xcoff -S -emit-llvm -x c++ < %s | \
+// RUN:   FileCheck %s
+
+namespace test1 {
+struct __attribute__((__aligned__(2))) S {
+  double d;
+};
+
+S s;
+
+// CHECK: @{{.*}}test1{{.*}}s{{.*}} = global %"struct.test1::S" zeroinitializer, align 8
+} // namespace test1
+
+namespace test2 {
+struct __attribute__((__aligned__(2), packed)) S {
+  double d;
+};
+
+S s;
+
+// CHECK: @{{.*}}test2{{.*}}s{{.*}} = global %"struct.test2::S" zeroinitializer, align 2
+} // namespace test2
+
+namespace test3 {
+struct __attribute__((__aligned__(16))) S {
+  double d;
+};
+
+S s;
+
+// CHECK: @{{.*}}test3{{.*}}s{{.*}} = global %"struct.test3::S" zeroinitializer, align 16
+} // namespace test3
+
+namespace test4 {
+struct __attribute__((aligned(2))) SS {
+  double d;
+};
+
+struct S {
+  struct SS ss;
+} s;
+
+// CHECK: @{{.*}}test4{{.*}}s{{.*}} = global %"struct.test4::S" zeroinitializer, align 8
+} // namespace test4
+
+namespace test5 {
+struct __attribute__((aligned(2), packed)) SS {
+  double d;
+};
+
+struct S {
+  struct SS ss;
+} s;
+
+// CHECK: @{{.*}}test5{{.*}}s{{.*}} = global %"struct.test5::S" zeroinitializer, align 2
+} // namespace test5