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-rw-r--r--clang/lib/AST/RecordLayout.cpp4
-rw-r--r--clang/lib/AST/RecordLayoutBuilder.cpp62
-rw-r--r--clang/lib/Sema/SemaDeclAttr.cpp25
3 files changed, 73 insertions, 18 deletions
diff --git a/clang/lib/AST/RecordLayout.cpp b/clang/lib/AST/RecordLayout.cpp
index b2c244e3790..4cee2e06311 100644
--- a/clang/lib/AST/RecordLayout.cpp
+++ b/clang/lib/AST/RecordLayout.cpp
@@ -58,7 +58,7 @@ ASTRecordLayout::ASTRecordLayout(const ASTContext &Ctx,
const CXXRecordDecl *PrimaryBase,
bool IsPrimaryBaseVirtual,
const CXXRecordDecl *BaseSharingVBPtr,
- bool HasZeroSizedSubObject,
+ bool EndsWithZeroSizedObject,
bool LeadsWithZeroSizedBase,
const BaseOffsetsMapTy& BaseOffsets,
const VBaseOffsetsMapTy& VBaseOffsets)
@@ -82,7 +82,7 @@ ASTRecordLayout::ASTRecordLayout(const ASTContext &Ctx,
CXXInfo->VBPtrOffset = vbptroffset;
CXXInfo->HasExtendableVFPtr = hasExtendableVFPtr;
CXXInfo->BaseSharingVBPtr = BaseSharingVBPtr;
- CXXInfo->HasZeroSizedSubObject = HasZeroSizedSubObject;
+ CXXInfo->EndsWithZeroSizedObject = EndsWithZeroSizedObject;
CXXInfo->LeadsWithZeroSizedBase = LeadsWithZeroSizedBase;
diff --git a/clang/lib/AST/RecordLayoutBuilder.cpp b/clang/lib/AST/RecordLayoutBuilder.cpp
index 6a7d5144c8c..d03273f9175 100644
--- a/clang/lib/AST/RecordLayoutBuilder.cpp
+++ b/clang/lib/AST/RecordLayoutBuilder.cpp
@@ -2228,7 +2228,8 @@ public:
/// laid out.
void initializeCXXLayout(const CXXRecordDecl *RD);
void layoutNonVirtualBases(const CXXRecordDecl *RD);
- void layoutNonVirtualBase(const CXXRecordDecl *BaseDecl,
+ void layoutNonVirtualBase(const CXXRecordDecl *RD,
+ const CXXRecordDecl *BaseDecl,
const ASTRecordLayout &BaseLayout,
const ASTRecordLayout *&PreviousBaseLayout);
void injectVFPtr(const CXXRecordDecl *RD);
@@ -2334,7 +2335,7 @@ MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
if (!MaxFieldAlignment.isZero())
Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
// Track zero-sized subobjects here where it's already available.
- EndsWithZeroSizedObject = Layout.hasZeroSizedSubObject();
+ EndsWithZeroSizedObject = Layout.endsWithZeroSizedObject();
// Respect required alignment, this is necessary because we may have adjusted
// the alignment in the case of pragam pack. Note that the required alignment
// doesn't actually apply to the struct alignment at this point.
@@ -2369,7 +2370,7 @@ MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
if (auto RT =
FD->getType()->getBaseElementTypeUnsafe()->getAs<RecordType>()) {
auto const &Layout = Context.getASTRecordLayout(RT->getDecl());
- EndsWithZeroSizedObject = Layout.hasZeroSizedSubObject();
+ EndsWithZeroSizedObject = Layout.endsWithZeroSizedObject();
FieldRequiredAlignment = std::max(FieldRequiredAlignment,
Layout.getRequiredAlignment());
}
@@ -2502,7 +2503,7 @@ MicrosoftRecordLayoutBuilder::layoutNonVirtualBases(const CXXRecordDecl *RD) {
LeadsWithZeroSizedBase = BaseLayout.leadsWithZeroSizedBase();
}
// Lay out the base.
- layoutNonVirtualBase(BaseDecl, BaseLayout, PreviousBaseLayout);
+ layoutNonVirtualBase(RD, BaseDecl, BaseLayout, PreviousBaseLayout);
}
// Figure out if we need a fresh VFPtr for this class.
if (!PrimaryBase && RD->isDynamicClass())
@@ -2531,7 +2532,7 @@ MicrosoftRecordLayoutBuilder::layoutNonVirtualBases(const CXXRecordDecl *RD) {
LeadsWithZeroSizedBase = BaseLayout.leadsWithZeroSizedBase();
}
// Lay out the base.
- layoutNonVirtualBase(BaseDecl, BaseLayout, PreviousBaseLayout);
+ layoutNonVirtualBase(RD, BaseDecl, BaseLayout, PreviousBaseLayout);
VBPtrOffset = Bases[BaseDecl] + BaseLayout.getNonVirtualSize();
}
// Set our VBPtroffset if we know it at this point.
@@ -2543,15 +2544,32 @@ MicrosoftRecordLayoutBuilder::layoutNonVirtualBases(const CXXRecordDecl *RD) {
}
}
+static bool recordUsesEBO(const RecordDecl *RD) {
+ if (!isa<CXXRecordDecl>(RD))
+ return false;
+ if (RD->hasAttr<EmptyBasesAttr>())
+ return true;
+ if (auto *LVA = RD->getAttr<LayoutVersionAttr>())
+ // TODO: Double check with the next version of MSVC.
+ if (LVA->getVersion() <= LangOptions::MSVC2015)
+ return false;
+ // TODO: Some later version of MSVC will change the default behavior of the
+ // compiler to enable EBO by default. When this happens, we will need an
+ // additional isCompatibleWithMSVC check.
+ return false;
+}
+
void MicrosoftRecordLayoutBuilder::layoutNonVirtualBase(
+ const CXXRecordDecl *RD,
const CXXRecordDecl *BaseDecl,
const ASTRecordLayout &BaseLayout,
const ASTRecordLayout *&PreviousBaseLayout) {
// Insert padding between two bases if the left first one is zero sized or
// contains a zero sized subobject and the right is zero sized or one leads
// with a zero sized base.
- if (PreviousBaseLayout && PreviousBaseLayout->hasZeroSizedSubObject() &&
- BaseLayout.leadsWithZeroSizedBase())
+ bool MDCUsesEBO = recordUsesEBO(RD);
+ if (PreviousBaseLayout && PreviousBaseLayout->endsWithZeroSizedObject() &&
+ BaseLayout.leadsWithZeroSizedBase() && !MDCUsesEBO)
Size++;
ElementInfo Info = getAdjustedElementInfo(BaseLayout);
CharUnits BaseOffset;
@@ -2560,14 +2578,23 @@ void MicrosoftRecordLayoutBuilder::layoutNonVirtualBase(
bool FoundBase = false;
if (UseExternalLayout) {
FoundBase = External.getExternalNVBaseOffset(BaseDecl, BaseOffset);
- if (FoundBase)
+ if (FoundBase) {
assert(BaseOffset >= Size && "base offset already allocated");
+ Size = BaseOffset;
+ }
}
- if (!FoundBase)
- BaseOffset = Size.alignTo(Info.Alignment);
+ if (!FoundBase) {
+ if (MDCUsesEBO && BaseDecl->isEmpty() &&
+ BaseLayout.getNonVirtualSize() == CharUnits::Zero()) {
+ BaseOffset = CharUnits::Zero();
+ } else {
+ // Otherwise, lay the base out at the end of the MDC.
+ BaseOffset = Size = Size.alignTo(Info.Alignment);
+ }
+ }
Bases.insert(std::make_pair(BaseDecl, BaseOffset));
- Size = BaseOffset + BaseLayout.getNonVirtualSize();
+ Size += BaseLayout.getNonVirtualSize();
PreviousBaseLayout = &BaseLayout;
}
@@ -2746,8 +2773,9 @@ void MicrosoftRecordLayoutBuilder::layoutVirtualBases(const CXXRecordDecl *RD) {
// with a zero sized base. The padding between virtual bases is 4
// bytes (in both 32 and 64 bits modes) and always involves rounding up to
// the required alignment, we don't know why.
- if ((PreviousBaseLayout && PreviousBaseLayout->hasZeroSizedSubObject() &&
- BaseLayout.leadsWithZeroSizedBase()) || HasVtordisp) {
+ if ((PreviousBaseLayout && PreviousBaseLayout->endsWithZeroSizedObject() &&
+ BaseLayout.leadsWithZeroSizedBase() && !recordUsesEBO(RD)) ||
+ HasVtordisp) {
Size = Size.alignTo(VtorDispAlignment) + VtorDispSize;
Alignment = std::max(VtorDispAlignment, Alignment);
}
@@ -2785,8 +2813,10 @@ void MicrosoftRecordLayoutBuilder::finalizeLayout(const RecordDecl *RD) {
Size = Size.alignTo(RoundingAlignment);
}
if (Size.isZero()) {
- EndsWithZeroSizedObject = true;
- LeadsWithZeroSizedBase = true;
+ if (!recordUsesEBO(RD) || !cast<CXXRecordDecl>(RD)->isEmpty()) {
+ EndsWithZeroSizedObject = true;
+ LeadsWithZeroSizedBase = true;
+ }
// Zero-sized structures have size equal to their alignment if a
// __declspec(align) came into play.
if (RequiredAlignment >= MinEmptyStructSize)
@@ -2919,7 +2949,7 @@ ASTContext::getASTRecordLayout(const RecordDecl *D) const {
NewEntry = new (*this) ASTRecordLayout(
*this, Builder.Size, Builder.Alignment, Builder.RequiredAlignment,
Builder.HasOwnVFPtr, Builder.HasOwnVFPtr || Builder.PrimaryBase,
- Builder.VBPtrOffset, Builder.NonVirtualSize,
+ Builder.VBPtrOffset, Builder.DataSize,
Builder.FieldOffsets.data(), Builder.FieldOffsets.size(),
Builder.NonVirtualSize, Builder.Alignment, CharUnits::Zero(),
Builder.PrimaryBase, false, Builder.SharedVBPtrBase,
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index aeacb4a6fe4..a1a1b9e7b5e 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -4968,6 +4968,24 @@ static void handleX86ForceAlignArgPointerAttr(Sema &S, Decl *D,
Attr.getAttributeSpellingListIndex()));
}
+static void handleLayoutVersion(Sema &S, Decl *D, const AttributeList &Attr) {
+ uint32_t Version;
+ Expr *VersionExpr = static_cast<Expr *>(Attr.getArgAsExpr(0));
+ if (!checkUInt32Argument(S, Attr, Attr.getArgAsExpr(0), Version))
+ return;
+
+ // TODO: Investigate what happens with the next major version of MSVC.
+ if (Version != LangOptions::MSVC2015) {
+ S.Diag(Attr.getLoc(), diag::err_attribute_argument_out_of_bounds)
+ << Attr.getName() << Version << VersionExpr->getSourceRange();
+ return;
+ }
+
+ D->addAttr(::new (S.Context)
+ LayoutVersionAttr(Attr.getRange(), S.Context, Version,
+ Attr.getAttributeSpellingListIndex()));
+}
+
DLLImportAttr *Sema::mergeDLLImportAttr(Decl *D, SourceRange Range,
unsigned AttrSpellingListIndex) {
if (D->hasAttr<DLLExportAttr>()) {
@@ -5749,6 +5767,12 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
break;
// Microsoft attributes:
+ case AttributeList::AT_EmptyBases:
+ handleSimpleAttribute<EmptyBasesAttr>(S, D, Attr);
+ break;
+ case AttributeList::AT_LayoutVersion:
+ handleLayoutVersion(S, D, Attr);
+ break;
case AttributeList::AT_MSNoVTable:
handleSimpleAttribute<MSNoVTableAttr>(S, D, Attr);
break;
@@ -5767,6 +5791,7 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
case AttributeList::AT_Thread:
handleDeclspecThreadAttr(S, D, Attr);
break;
+
case AttributeList::AT_AbiTag:
handleAbiTagAttr(S, D, Attr);
break;
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