For P0784R7: compute whether a variable has constant destruction if it
has a constexpr destructor.
For constexpr variables, reject if the variable does not have constant
destruction. In all cases, do not emit runtime calls to the destructor
for variables with constant destruction.
llvm-svn: 373159
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index 091b2fe..f691993 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -10064,7 +10064,7 @@
return false;
// Variables that have destruction with side-effects are required.
- if (VD->getType().isDestructedType())
+ if (VD->needsDestruction(*this))
return true;
// Variables that have initialization with side-effects are required.
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 19a012b..9ebf1c3 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -2592,6 +2592,18 @@
!hasAttr<AlwaysDestroyAttr>()));
}
+QualType::DestructionKind
+VarDecl::needsDestruction(const ASTContext &Ctx) const {
+ if (EvaluatedStmt *Eval = Init.dyn_cast<EvaluatedStmt *>())
+ if (Eval->HasConstantDestruction)
+ return QualType::DK_none;
+
+ if (isNoDestroy(Ctx))
+ return QualType::DK_none;
+
+ return getType().isDestructedType();
+}
+
MemberSpecializationInfo *VarDecl::getMemberSpecializationInfo() const {
if (isStaticDataMember())
// FIXME: Remove ?
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 1b3ace0..33608db 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -744,6 +744,15 @@
/// evaluated, if any.
APValue::LValueBase EvaluatingDecl;
+ enum class EvaluatingDeclKind {
+ None,
+ /// We're evaluating the construction of EvaluatingDecl.
+ Ctor,
+ /// We're evaluating the destruction of EvaluatingDecl.
+ Dtor,
+ };
+ EvaluatingDeclKind IsEvaluatingDecl = EvaluatingDeclKind::None;
+
/// EvaluatingDeclValue - This is the value being constructed for the
/// declaration whose initializer is being evaluated, if any.
APValue *EvaluatingDeclValue;
@@ -902,8 +911,10 @@
discardCleanups();
}
- void setEvaluatingDecl(APValue::LValueBase Base, APValue &Value) {
+ void setEvaluatingDecl(APValue::LValueBase Base, APValue &Value,
+ EvaluatingDeclKind EDK = EvaluatingDeclKind::Ctor) {
EvaluatingDecl = Base;
+ IsEvaluatingDecl = EDK;
EvaluatingDeclValue = &Value;
}
@@ -2913,8 +2924,8 @@
/// Diagnose an attempt to read from any unreadable field within the specified
/// type, which might be a class type.
-static bool diagnoseUnreadableFields(EvalInfo &Info, const Expr *E,
- QualType T) {
+static bool diagnoseMutableFields(EvalInfo &Info, const Expr *E, AccessKinds AK,
+ QualType T) {
CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
if (!RD)
return false;
@@ -2929,17 +2940,17 @@
// FIXME: Add core issue number for the union case.
if (Field->isMutable() &&
(RD->isUnion() || isReadByLvalueToRvalueConversion(Field->getType()))) {
- Info.FFDiag(E, diag::note_constexpr_ltor_mutable, 1) << Field;
+ Info.FFDiag(E, diag::note_constexpr_access_mutable, 1) << AK << Field;
Info.Note(Field->getLocation(), diag::note_declared_at);
return true;
}
- if (diagnoseUnreadableFields(Info, E, Field->getType()))
+ if (diagnoseMutableFields(Info, E, AK, Field->getType()))
return true;
}
for (auto &BaseSpec : RD->bases())
- if (diagnoseUnreadableFields(Info, E, BaseSpec.getType()))
+ if (diagnoseMutableFields(Info, E, AK, BaseSpec.getType()))
return true;
// All mutable fields were empty, and thus not actually read.
@@ -2947,7 +2958,8 @@
}
static bool lifetimeStartedInEvaluation(EvalInfo &Info,
- APValue::LValueBase Base) {
+ APValue::LValueBase Base,
+ bool MutableSubobject = false) {
// A temporary we created.
if (Base.getCallIndex())
return true;
@@ -2956,19 +2968,42 @@
if (!Evaluating)
return false;
- // The variable whose initializer we're evaluating.
- if (auto *BaseD = Base.dyn_cast<const ValueDecl*>())
- if (declaresSameEntity(Evaluating, BaseD))
- return true;
+ auto *BaseD = Base.dyn_cast<const ValueDecl*>();
- // A temporary lifetime-extended by the variable whose initializer we're
- // evaluating.
- if (auto *BaseE = Base.dyn_cast<const Expr *>())
- if (auto *BaseMTE = dyn_cast<MaterializeTemporaryExpr>(BaseE))
- if (declaresSameEntity(BaseMTE->getExtendingDecl(), Evaluating))
- return true;
+ switch (Info.IsEvaluatingDecl) {
+ case EvalInfo::EvaluatingDeclKind::None:
+ return false;
- return false;
+ case EvalInfo::EvaluatingDeclKind::Ctor:
+ // The variable whose initializer we're evaluating.
+ if (BaseD)
+ return declaresSameEntity(Evaluating, BaseD);
+
+ // A temporary lifetime-extended by the variable whose initializer we're
+ // evaluating.
+ if (auto *BaseE = Base.dyn_cast<const Expr *>())
+ if (auto *BaseMTE = dyn_cast<MaterializeTemporaryExpr>(BaseE))
+ return declaresSameEntity(BaseMTE->getExtendingDecl(), Evaluating);
+ return false;
+
+ case EvalInfo::EvaluatingDeclKind::Dtor:
+ // C++2a [expr.const]p6:
+ // [during constant destruction] the lifetime of a and its non-mutable
+ // subobjects (but not its mutable subobjects) [are] considered to start
+ // within e.
+ //
+ // FIXME: We can meaningfully extend this to cover non-const objects, but
+ // we will need special handling: we should be able to access only
+ // subobjects of such objects that are themselves declared const.
+ if (!BaseD ||
+ !(BaseD->getType().isConstQualified() ||
+ BaseD->getType()->isReferenceType()) ||
+ MutableSubobject)
+ return false;
+ return declaresSameEntity(Evaluating, BaseD);
+ }
+
+ llvm_unreachable("unknown evaluating decl kind");
}
namespace {
@@ -2986,13 +3021,13 @@
CompleteObject(APValue::LValueBase Base, APValue *Value, QualType Type)
: Base(Base), Value(Value), Type(Type) {}
- bool mayReadMutableMembers(EvalInfo &Info) const {
+ bool mayAccessMutableMembers(EvalInfo &Info, AccessKinds AK) const {
// In C++14 onwards, it is permitted to read a mutable member whose
// lifetime began within the evaluation.
// FIXME: Should we also allow this in C++11?
if (!Info.getLangOpts().CPlusPlus14)
return false;
- return lifetimeStartedInEvaluation(Info, Base);
+ return lifetimeStartedInEvaluation(Info, Base, /*MutableSubobject*/true);
}
explicit operator bool() const { return !Type.isNull(); }
@@ -3097,9 +3132,9 @@
// things we need to check: if there are any mutable subobjects, we
// cannot perform this read. (This only happens when performing a trivial
// copy or assignment.)
- if (ObjType->isRecordType() && isRead(handler.AccessKind) &&
- !Obj.mayReadMutableMembers(Info) &&
- diagnoseUnreadableFields(Info, E, ObjType))
+ if (ObjType->isRecordType() &&
+ !Obj.mayAccessMutableMembers(Info, handler.AccessKind) &&
+ diagnoseMutableFields(Info, E, handler.AccessKind, ObjType))
return handler.failed();
}
@@ -3167,10 +3202,10 @@
: O->getComplexFloatReal(), ObjType);
}
} else if (const FieldDecl *Field = getAsField(Sub.Entries[I])) {
- if (Field->isMutable() && isRead(handler.AccessKind) &&
- !Obj.mayReadMutableMembers(Info)) {
- Info.FFDiag(E, diag::note_constexpr_ltor_mutable, 1)
- << Field;
+ if (Field->isMutable() &&
+ !Obj.mayAccessMutableMembers(Info, handler.AccessKind)) {
+ Info.FFDiag(E, diag::note_constexpr_access_mutable, 1)
+ << handler.AccessKind << Field;
Info.Note(Field->getLocation(), diag::note_declared_at);
return handler.failed();
}
@@ -3427,8 +3462,7 @@
// the variable we're reading must be const.
if (!Frame) {
if (Info.getLangOpts().CPlusPlus14 &&
- declaresSameEntity(
- VD, Info.EvaluatingDecl.dyn_cast<const ValueDecl *>())) {
+ lifetimeStartedInEvaluation(Info, LVal.Base)) {
// OK, we can read and modify an object if we're in the process of
// evaluating its initializer, because its lifetime began in this
// evaluation.
@@ -3518,11 +3552,14 @@
// int x = ++r;
// constexpr int k = r;
// Therefore we use the C++14 rules in C++11 too.
- const ValueDecl *VD = Info.EvaluatingDecl.dyn_cast<const ValueDecl*>();
- const ValueDecl *ED = MTE->getExtendingDecl();
+ //
+ // Note that temporaries whose lifetimes began while evaluating a
+ // variable's constructor are not usable while evaluating the
+ // corresponding destructor, not even if they're of const-qualified
+ // types.
if (!(BaseType.isConstQualified() &&
BaseType->isIntegralOrEnumerationType()) &&
- !(VD && VD->getCanonicalDecl() == ED->getCanonicalDecl())) {
+ !lifetimeStartedInEvaluation(Info, LVal.Base)) {
if (!IsAccess)
return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
Info.FFDiag(E, diag::note_constexpr_access_static_temporary, 1) << AK;
@@ -13282,6 +13319,41 @@
CheckMemoryLeaks(Info);
}
+bool VarDecl::evaluateDestruction(
+ SmallVectorImpl<PartialDiagnosticAt> &Notes) const {
+ assert(getEvaluatedValue() && !getEvaluatedValue()->isAbsent() &&
+ "cannot evaluate destruction of non-constant-initialized variable");
+
+ Expr::EvalStatus EStatus;
+ EStatus.Diag = &Notes;
+
+ // Make a copy of the value for the destructor to mutate.
+ APValue DestroyedValue = *getEvaluatedValue();
+
+ EvalInfo Info(getASTContext(), EStatus, EvalInfo::EM_ConstantExpression);
+ Info.setEvaluatingDecl(this, DestroyedValue,
+ EvalInfo::EvaluatingDeclKind::Dtor);
+ Info.InConstantContext = true;
+
+ SourceLocation DeclLoc = getLocation();
+ QualType DeclTy = getType();
+
+ LValue LVal;
+ LVal.set(this);
+
+ // FIXME: Consider storing whether this variable has constant destruction in
+ // the EvaluatedStmt so that CodeGen can query it.
+ if (!HandleDestruction(Info, DeclLoc, LVal.Base, DestroyedValue, DeclTy) ||
+ EStatus.HasSideEffects)
+ return false;
+
+ if (!Info.discardCleanups())
+ llvm_unreachable("Unhandled cleanup; missing full expression marker?");
+
+ ensureEvaluatedStmt()->HasConstantDestruction = true;
+ return true;
+}
+
/// isEvaluatable - Call EvaluateAsRValue to see if this expression can be
/// constant folded, but discard the result.
bool Expr::isEvaluatable(const ASTContext &Ctx, SideEffectsKind SEK) const {
diff --git a/clang/lib/AST/Interp/Interp.cpp b/clang/lib/AST/Interp/Interp.cpp
index c9ace13..1a8109c 100644
--- a/clang/lib/AST/Interp/Interp.cpp
+++ b/clang/lib/AST/Interp/Interp.cpp
@@ -275,7 +275,7 @@
const SourceInfo &Loc = S.Current->getSource(OpPC);
const FieldDecl *Field = Ptr.getField();
- S.FFDiag(Loc, diag::note_constexpr_ltor_mutable, 1) << Field;
+ S.FFDiag(Loc, diag::note_constexpr_access_mutable, 1) << AK_Read << Field;
S.Note(Field->getLocation(), diag::note_declared_at);
return false;
}
diff --git a/clang/lib/AST/TextNodeDumper.cpp b/clang/lib/AST/TextNodeDumper.cpp
index d1915fd..a540346 100644
--- a/clang/lib/AST/TextNodeDumper.cpp
+++ b/clang/lib/AST/TextNodeDumper.cpp
@@ -1384,6 +1384,8 @@
break;
}
}
+ if (D->needsDestruction(D->getASTContext()))
+ OS << " destroyed";
if (D->isParameterPack())
OS << " pack";
}
diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 7fa262c..0a0ba70 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -3093,7 +3093,7 @@
// Deactivate the cleanup for the callee-destructed param that was pushed.
if (hasAggregateEvaluationKind(type) && !CurFuncIsThunk &&
type->getAs<RecordType>()->getDecl()->isParamDestroyedInCallee() &&
- type.isDestructedType()) {
+ param->needsDestruction(getContext())) {
EHScopeStack::stable_iterator cleanup =
CalleeDestructedParamCleanups.lookup(cast<ParmVarDecl>(param));
assert(cleanup.isValid() &&
diff --git a/clang/lib/CodeGen/CGClass.cpp b/clang/lib/CodeGen/CGClass.cpp
index c8bb63c..76ab885 100644
--- a/clang/lib/CodeGen/CGClass.cpp
+++ b/clang/lib/CodeGen/CGClass.cpp
@@ -2083,7 +2083,7 @@
if (CGF.getTarget().getCXXABI().areArgsDestroyedLeftToRightInCallee()) {
// If the parameters are callee-cleanup, it's not safe to forward.
for (auto *P : Ctor->parameters())
- if (P->getType().isDestructedType())
+ if (P->needsDestruction(CGF.getContext()))
return false;
// Likewise if they're inalloca.
diff --git a/clang/lib/CodeGen/CGDecl.cpp b/clang/lib/CodeGen/CGDecl.cpp
index a9e0161..5c0d52a 100644
--- a/clang/lib/CodeGen/CGDecl.cpp
+++ b/clang/lib/CodeGen/CGDecl.cpp
@@ -305,14 +305,6 @@
return Addr;
}
-/// hasNontrivialDestruction - Determine whether a type's destruction is
-/// non-trivial. If so, and the variable uses static initialization, we must
-/// register its destructor to run on exit.
-static bool hasNontrivialDestruction(QualType T) {
- CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
- return RD && !RD->hasTrivialDestructor();
-}
-
/// AddInitializerToStaticVarDecl - Add the initializer for 'D' to the
/// global variable that has already been created for it. If the initializer
/// has a different type than GV does, this may free GV and return a different
@@ -372,7 +364,7 @@
emitter.finalize(GV);
- if (hasNontrivialDestruction(D.getType()) && HaveInsertPoint()) {
+ if (D.needsDestruction(getContext()) && HaveInsertPoint()) {
// We have a constant initializer, but a nontrivial destructor. We still
// need to perform a guarded "initialization" in order to register the
// destructor.
@@ -1994,7 +1986,7 @@
const VarDecl &D = *emission.Variable;
// Check the type for a cleanup.
- if (QualType::DestructionKind dtorKind = D.getType().isDestructedType())
+ if (QualType::DestructionKind dtorKind = D.needsDestruction(getContext()))
emitAutoVarTypeCleanup(emission, dtorKind);
// In GC mode, honor objc_precise_lifetime.
@@ -2404,7 +2396,8 @@
// cleanup.
if (hasAggregateEvaluationKind(Ty) && !CurFuncIsThunk &&
Ty->getAs<RecordType>()->getDecl()->isParamDestroyedInCallee()) {
- if (QualType::DestructionKind DtorKind = Ty.isDestructedType()) {
+ if (QualType::DestructionKind DtorKind =
+ D.needsDestruction(getContext())) {
assert((DtorKind == QualType::DK_cxx_destructor ||
DtorKind == QualType::DK_nontrivial_c_struct) &&
"unexpected destructor type");
diff --git a/clang/lib/CodeGen/CGDeclCXX.cpp b/clang/lib/CodeGen/CGDeclCXX.cpp
index 7a0605b..a54e5dc 100644
--- a/clang/lib/CodeGen/CGDeclCXX.cpp
+++ b/clang/lib/CodeGen/CGDeclCXX.cpp
@@ -73,16 +73,10 @@
// that isn't balanced out by a destructor call as intended by the
// attribute. This also checks for -fno-c++-static-destructors and
// bails even if the attribute is not present.
- if (D.isNoDestroy(CGF.getContext()))
- return;
-
- CodeGenModule &CGM = CGF.CGM;
+ QualType::DestructionKind DtorKind = D.needsDestruction(CGF.getContext());
// FIXME: __attribute__((cleanup)) ?
- QualType Type = D.getType();
- QualType::DestructionKind DtorKind = Type.isDestructedType();
-
switch (DtorKind) {
case QualType::DK_none:
return;
@@ -101,6 +95,9 @@
llvm::FunctionCallee Func;
llvm::Constant *Argument;
+ CodeGenModule &CGM = CGF.CGM;
+ QualType Type = D.getType();
+
// Special-case non-array C++ destructors, if they have the right signature.
// Under some ABIs, destructors return this instead of void, and cannot be
// passed directly to __cxa_atexit if the target does not allow this
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 486832b..37e2533 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -3809,9 +3809,9 @@
return;
llvm::Constant *Init = nullptr;
- CXXRecordDecl *RD = ASTTy->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
bool NeedsGlobalCtor = false;
- bool NeedsGlobalDtor = RD && !RD->hasTrivialDestructor();
+ bool NeedsGlobalDtor =
+ D->needsDestruction(getContext()) == QualType::DK_cxx_destructor;
const VarDecl *InitDecl;
const Expr *InitExpr = D->getAnyInitializer(InitDecl);
diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index 0371853..35e7072 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -350,7 +350,7 @@
// If we have the only definition, we don't need a thread wrapper if we
// will emit the value as a constant.
if (isUniqueGVALinkage(getContext().GetGVALinkageForVariable(VD)))
- return !VD->getType().isDestructedType() && InitDecl->evaluateValue();
+ return !VD->needsDestruction(getContext()) && InitDecl->evaluateValue();
// Otherwise, we need a thread wrapper unless we know that every
// translation unit will emit the value as a constant. We rely on
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index c03e4dc..d21d268 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -13398,6 +13398,19 @@
}
if (Destructor->isTrivial()) return;
+
+ // If the destructor is constexpr, check whether the variable has constant
+ // destruction now.
+ if (Destructor->isConstexpr() && VD->evaluateValue()) {
+ SmallVector<PartialDiagnosticAt, 8> Notes;
+ if (!VD->evaluateDestruction(Notes) && VD->isConstexpr()) {
+ Diag(VD->getLocation(),
+ diag::err_constexpr_var_requires_const_destruction) << VD;
+ for (unsigned I = 0, N = Notes.size(); I != N; ++I)
+ Diag(Notes[I].first, Notes[I].second);
+ }
+ }
+
if (!VD->hasGlobalStorage()) return;
// Emit warning for non-trivial dtor in global scope (a real global,
diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index e9cf366..7692818 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -1390,10 +1390,11 @@
if (uint64_t Val = Record.readInt()) {
VD->setInit(Record.readExpr());
- if (Val > 1) { // IsInitKnownICE = 1, IsInitNotICE = 2, IsInitICE = 3
+ if (Val > 1) {
EvaluatedStmt *Eval = VD->ensureEvaluatedStmt();
Eval->CheckedICE = true;
- Eval->IsICE = Val == 3;
+ Eval->IsICE = (Val & 1) != 0;
+ Eval->HasConstantDestruction = (Val & 4) != 0;
}
}
diff --git a/clang/lib/Serialization/ASTWriterDecl.cpp b/clang/lib/Serialization/ASTWriterDecl.cpp
index b713155..2c22587 100644
--- a/clang/lib/Serialization/ASTWriterDecl.cpp
+++ b/clang/lib/Serialization/ASTWriterDecl.cpp
@@ -968,7 +968,14 @@
Record.push_back(D->getLinkageInternal());
if (D->getInit()) {
- Record.push_back(!D->isInitKnownICE() ? 1 : (D->isInitICE() ? 3 : 2));
+ if (!D->isInitKnownICE())
+ Record.push_back(1);
+ else {
+ Record.push_back(
+ 2 |
+ (D->isInitICE() ? 1 : 0) |
+ (D->ensureEvaluatedStmt()->HasConstantDestruction ? 4 : 0));
+ }
Record.AddStmt(D->getInit());
} else {
Record.push_back(0);
@@ -2140,7 +2147,7 @@
Abv->Add(BitCodeAbbrevOp(0)); // ImplicitParamKind
Abv->Add(BitCodeAbbrevOp(0)); // EscapingByref
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3)); // Linkage
- Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 2)); // IsInitICE (local)
+ Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3)); // IsInitICE (local)
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 2)); // VarKind (local enum)
// Type Source Info
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));