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-rw-r--r--clang/lib/CodeGen/CGExprAgg.cpp86
1 files changed, 53 insertions, 33 deletions
diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index 959086891c8..e2871e3d0e8 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -337,7 +337,8 @@ void AggExprEmitter::EmitFinalDestCopy(QualType type, const LValue &src,
AggValueSlot srcAgg =
AggValueSlot::forLValue(src, AggValueSlot::IsDestructed,
- needsGC(type), AggValueSlot::IsAliased);
+ needsGC(type), AggValueSlot::IsAliased,
+ AggValueSlot::MayOverlap);
EmitCopy(type, Dest, srcAgg);
}
@@ -348,7 +349,7 @@ void AggExprEmitter::EmitFinalDestCopy(QualType type, const LValue &src,
void AggExprEmitter::EmitCopy(QualType type, const AggValueSlot &dest,
const AggValueSlot &src) {
if (dest.requiresGCollection()) {
- CharUnits sz = CGF.getContext().getTypeSizeInChars(type);
+ CharUnits sz = dest.getPreferredSize(CGF.getContext(), type);
llvm::Value *size = llvm::ConstantInt::get(CGF.SizeTy, sz.getQuantity());
CGF.CGM.getObjCRuntime().EmitGCMemmoveCollectable(CGF,
dest.getAddress(),
@@ -362,7 +363,7 @@ void AggExprEmitter::EmitCopy(QualType type, const AggValueSlot &dest,
// the two sides.
LValue DestLV = CGF.MakeAddrLValue(dest.getAddress(), type);
LValue SrcLV = CGF.MakeAddrLValue(src.getAddress(), type);
- CGF.EmitAggregateCopy(DestLV, SrcLV, type,
+ CGF.EmitAggregateCopy(DestLV, SrcLV, type, dest.mayOverlap(),
dest.isVolatile() || src.isVolatile());
}
@@ -759,6 +760,7 @@ void AggExprEmitter::VisitCastExpr(CastExpr *E) {
valueDest.isExternallyDestructed(),
valueDest.requiresGCollection(),
valueDest.isPotentiallyAliased(),
+ AggValueSlot::DoesNotOverlap,
AggValueSlot::IsZeroed);
}
@@ -986,7 +988,8 @@ void AggExprEmitter::VisitBinAssign(const BinaryOperator *E) {
EmitCopy(E->getLHS()->getType(),
AggValueSlot::forLValue(LHS, AggValueSlot::IsDestructed,
needsGC(E->getLHS()->getType()),
- AggValueSlot::IsAliased),
+ AggValueSlot::IsAliased,
+ AggValueSlot::MayOverlap),
Dest);
return;
}
@@ -1007,7 +1010,8 @@ void AggExprEmitter::VisitBinAssign(const BinaryOperator *E) {
AggValueSlot LHSSlot =
AggValueSlot::forLValue(LHS, AggValueSlot::IsDestructed,
needsGC(E->getLHS()->getType()),
- AggValueSlot::IsAliased);
+ AggValueSlot::IsAliased,
+ AggValueSlot::MayOverlap);
// A non-volatile aggregate destination might have volatile member.
if (!LHSSlot.isVolatile() &&
CGF.hasVolatileMember(E->getLHS()->getType()))
@@ -1185,6 +1189,7 @@ AggExprEmitter::EmitInitializationToLValue(Expr *E, LValue LV) {
AggValueSlot::IsDestructed,
AggValueSlot::DoesNotNeedGCBarriers,
AggValueSlot::IsNotAliased,
+ AggValueSlot::MayOverlap,
Dest.isZeroed()));
return;
case TEK_Scalar:
@@ -1283,11 +1288,12 @@ void AggExprEmitter::VisitInitListExpr(InitListExpr *E) {
Address V = CGF.GetAddressOfDirectBaseInCompleteClass(
Dest.getAddress(), CXXRD, BaseRD,
/*isBaseVirtual*/ false);
- AggValueSlot AggSlot =
- AggValueSlot::forAddr(V, Qualifiers(),
- AggValueSlot::IsDestructed,
- AggValueSlot::DoesNotNeedGCBarriers,
- AggValueSlot::IsNotAliased);
+ AggValueSlot AggSlot = AggValueSlot::forAddr(
+ V, Qualifiers(),
+ AggValueSlot::IsDestructed,
+ AggValueSlot::DoesNotNeedGCBarriers,
+ AggValueSlot::IsNotAliased,
+ CGF.overlapForBaseInit(CXXRD, BaseRD, Base.isVirtual()));
CGF.EmitAggExpr(E->getInit(curInitIndex++), AggSlot);
if (QualType::DestructionKind dtorKind =
@@ -1468,7 +1474,9 @@ void AggExprEmitter::VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E,
// If the subexpression is an ArrayInitLoopExpr, share its cleanup.
auto elementSlot = AggValueSlot::forLValue(
elementLV, AggValueSlot::IsDestructed,
- AggValueSlot::DoesNotNeedGCBarriers, AggValueSlot::IsNotAliased);
+ AggValueSlot::DoesNotNeedGCBarriers,
+ AggValueSlot::IsNotAliased,
+ AggValueSlot::DoesNotOverlap);
AggExprEmitter(CGF, elementSlot, false)
.VisitArrayInitLoopExpr(InnerLoop, outerBegin);
} else
@@ -1584,7 +1592,7 @@ static void CheckAggExprForMemSetUse(AggValueSlot &Slot, const Expr *E,
}
// If the type is 16-bytes or smaller, prefer individual stores over memset.
- CharUnits Size = CGF.getContext().getTypeSizeInChars(E->getType());
+ CharUnits Size = Slot.getPreferredSize(CGF.getContext(), E->getType());
if (Size <= CharUnits::fromQuantity(16))
return;
@@ -1630,13 +1638,37 @@ LValue CodeGenFunction::EmitAggExprToLValue(const Expr *E) {
LValue LV = MakeAddrLValue(Temp, E->getType());
EmitAggExpr(E, AggValueSlot::forLValue(LV, AggValueSlot::IsNotDestructed,
AggValueSlot::DoesNotNeedGCBarriers,
- AggValueSlot::IsNotAliased));
+ AggValueSlot::IsNotAliased,
+ AggValueSlot::DoesNotOverlap));
return LV;
}
-void CodeGenFunction::EmitAggregateCopy(LValue Dest, LValue Src,
- QualType Ty, bool isVolatile,
- bool isAssignment) {
+AggValueSlot::Overlap_t CodeGenFunction::overlapForBaseInit(
+ const CXXRecordDecl *RD, const CXXRecordDecl *BaseRD, bool IsVirtual) {
+ // Virtual bases are initialized first, in address order, so there's never
+ // any overlap during their initialization.
+ //
+ // FIXME: Under P0840, this is no longer true: the tail padding of a vbase
+ // of a field could be reused by a vbase of a containing class.
+ if (IsVirtual)
+ return AggValueSlot::DoesNotOverlap;
+
+ // If the base class is laid out entirely within the nvsize of the derived
+ // class, its tail padding cannot yet be initialized, so we can issue
+ // stores at the full width of the base class.
+ const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD);
+ if (Layout.getBaseClassOffset(BaseRD) +
+ getContext().getASTRecordLayout(BaseRD).getSize() <=
+ Layout.getNonVirtualSize())
+ return AggValueSlot::DoesNotOverlap;
+
+ // The tail padding may contain values we need to preserve.
+ return AggValueSlot::MayOverlap;
+}
+
+void CodeGenFunction::EmitAggregateCopy(LValue Dest, LValue Src, QualType Ty,
+ AggValueSlot::Overlap_t MayOverlap,
+ bool isVolatile) {
assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");
Address DestPtr = Dest.getAddress();
@@ -1669,12 +1701,11 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, LValue Src,
// implementation handles this case safely. If there is a libc that does not
// safely handle this, we can add a target hook.
- // Get data size info for this aggregate. If this is an assignment,
- // don't copy the tail padding, because we might be assigning into a
- // base subobject where the tail padding is claimed. Otherwise,
- // copying it is fine.
+ // Get data size info for this aggregate. Don't copy the tail padding if this
+ // might be a potentially-overlapping subobject, since the tail padding might
+ // be occupied by a different object. Otherwise, copying it is fine.
std::pair<CharUnits, CharUnits> TypeInfo;
- if (isAssignment)
+ if (MayOverlap)
TypeInfo = getContext().getTypeInfoDataSizeInChars(Ty);
else
TypeInfo = getContext().getTypeInfoInChars(Ty);
@@ -1686,22 +1717,11 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, LValue Src,
getContext().getAsArrayType(Ty))) {
QualType BaseEltTy;
SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
- TypeInfo = getContext().getTypeInfoDataSizeInChars(BaseEltTy);
- std::pair<CharUnits, CharUnits> LastElementTypeInfo;
- if (!isAssignment)
- LastElementTypeInfo = getContext().getTypeInfoInChars(BaseEltTy);
+ TypeInfo = getContext().getTypeInfoInChars(BaseEltTy);
assert(!TypeInfo.first.isZero());
SizeVal = Builder.CreateNUWMul(
SizeVal,
llvm::ConstantInt::get(SizeTy, TypeInfo.first.getQuantity()));
- if (!isAssignment) {
- SizeVal = Builder.CreateNUWSub(
- SizeVal,
- llvm::ConstantInt::get(SizeTy, TypeInfo.first.getQuantity()));
- SizeVal = Builder.CreateNUWAdd(
- SizeVal, llvm::ConstantInt::get(
- SizeTy, LastElementTypeInfo.first.getQuantity()));
- }
}
}
if (!SizeVal) {
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