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Defer building 'this' captures until we have left the capturing region 

and returned to the context in which 'this' should be captured.

This means we now always mark 'this' referenced from the context in
which it's actually referenced, rather than potentially from some
context nested within that.

llvm-svn: 362182
This commit is contained in:
Richard Smith 2019-05-31 01:17:04 +00:00
parent a35c50c9a4
commit b5a45bb77e
9 changed files with 46 additions and 67 deletions
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26
clang/include/clang/Sema/ScopeInfo.h
View File

@ -517,11 +517,6 @@ class Capture {
VarDecl *CapturedVar;
};
/// Expression to initialize a field of the given type. This is only required
/// if we are capturing ByVal and the variable's type has a non-trivial copy
/// constructor.
Expr *InitExpr = nullptr;
/// The source location at which the first capture occurred.
SourceLocation Loc;
@ -566,8 +561,8 @@ public:
enum IsThisCapture { ThisCapture };
Capture(IsThisCapture, bool IsNested, SourceLocation Loc,
QualType CaptureType, Expr *Cpy, const bool ByCopy, bool Invalid)
: InitExpr(Cpy), Loc(Loc), CaptureType(CaptureType),
QualType CaptureType, const bool ByCopy, bool Invalid)
: Loc(Loc), CaptureType(CaptureType),
Kind(ByCopy ? Cap_ByCopy : Cap_ByRef), Nested(IsNested),
CapturesThis(true), ODRUsed(false), NonODRUsed(false),
Invalid(Invalid) {}
@ -626,11 +621,6 @@ public:
/// the type of the non-static data member in the lambda/block structure
/// that would store this capture.
QualType getCaptureType() const { return CaptureType; }
Expr *getThisInitExpr() const {
assert(isThisCapture() && "no 'this' init expression for non-this capture");
return InitExpr;
}
};
class CapturingScopeInfo : public FunctionScopeInfo {
@ -681,7 +671,7 @@ public:
}
void addThisCapture(bool isNested, SourceLocation Loc, QualType CaptureType,
Expr *Cpy, bool ByCopy);
bool ByCopy);
/// Determine whether the C++ 'this' is captured.
bool isCXXThisCaptured() const { return CXXThisCaptureIndex != 0; }
@ -1025,12 +1015,12 @@ void FunctionScopeInfo::recordUseOfWeak(const ExprT *E, bool IsRead) {
Uses.push_back(WeakUseTy(E, IsRead));
}
inline void
CapturingScopeInfo::addThisCapture(bool isNested, SourceLocation Loc,
QualType CaptureType, Expr *Cpy,
const bool ByCopy) {
inline void CapturingScopeInfo::addThisCapture(bool isNested,
SourceLocation Loc,
QualType CaptureType,
bool ByCopy) {
Captures.push_back(Capture(Capture::ThisCapture, isNested, Loc, CaptureType,
Cpy, ByCopy, /*Invalid*/ false));
ByCopy, /*Invalid*/ false));
CXXThisCaptureIndex = Captures.size();
}

5
clang/include/clang/Sema/Sema.h
View File

@ -5291,6 +5291,11 @@ public:
const unsigned *const FunctionScopeIndexToStopAt = nullptr,
bool ByCopy = false);
/// Initialize the given 'this' capture with a suitable 'this' or '*this'
/// expression.
ExprResult performThisCaptureInitialization(const sema::Capture &Capture,
bool IsImplicit);
/// Determine whether the given type is the type of *this that is used
/// outside of the body of a member function for a type that is currently
/// being defined.

2
clang/lib/Sema/SemaDecl.cpp
View File

@ -12943,7 +12943,7 @@ static void RebuildLambdaScopeInfo(CXXMethodDecl *CallOperator,
} else if (C.capturesThis()) {
LSI->addThisCapture(/*Nested*/ false, C.getLocation(), I->getType(),
/*Expr*/ nullptr, C.getCaptureKind() == LCK_StarThis);
C.getCaptureKind() == LCK_StarThis);
} else {
LSI->addVLATypeCapture(C.getLocation(), I->getCapturedVLAType(),
I->getType());

35
clang/lib/Sema/SemaExprCXX.cpp
View File

@ -1134,24 +1134,6 @@ Sema::CXXThisScopeRAII::~CXXThisScopeRAII() {
}
}
static Expr *captureThis(Sema &S, ASTContext &Context, RecordDecl *RD,
QualType ThisTy, QualType CaptureType,
SourceLocation Loc, const bool ByCopy) {
Expr *This = new (Context) CXXThisExpr(Loc, ThisTy, /*isImplicit*/ true);
if (ByCopy) {
Expr *StarThis = S.CreateBuiltinUnaryOp(Loc, UO_Deref, This).get();
InitializedEntity Entity =
InitializedEntity::InitializeLambdaCapture(nullptr, CaptureType, Loc);
InitializationKind InitKind =
InitializationKind::CreateDirect(Loc, Loc, Loc);
InitializationSequence Init(S, Entity, InitKind, StarThis);
ExprResult ER = Init.Perform(S, Entity, InitKind, StarThis);
if (ER.isInvalid()) return nullptr;
return ER.get();
}
return This;
}
bool Sema::CheckCXXThisCapture(SourceLocation Loc, const bool Explicit,
bool BuildAndDiagnose, const unsigned *const FunctionScopeIndexToStopAt,
const bool ByCopy) {
@ -1241,13 +1223,10 @@ bool Sema::CheckCXXThisCapture(SourceLocation Loc, const bool Explicit,
dyn_cast<LambdaScopeInfo>(FunctionScopes[MaxFunctionScopesIndex])) &&
"Only a lambda can capture the enclosing object (referred to by "
"*this) by copy");
// FIXME: We need to delay this marking in PotentiallyPotentiallyEvaluated
// contexts.
QualType ThisTy = getCurrentThisType();
for (int idx = MaxFunctionScopesIndex; NumCapturingClosures;
--idx, --NumCapturingClosures) {
CapturingScopeInfo *CSI = cast<CapturingScopeInfo>(FunctionScopes[idx]);
Expr *ThisExpr = nullptr;
// The type of the corresponding data member (not a 'this' pointer if 'by
// copy').
@ -1261,20 +1240,8 @@ bool Sema::CheckCXXThisCapture(SourceLocation Loc, const bool Explicit,
CaptureType.removeLocalCVRQualifiers(Qualifiers::CVRMask);
}
if (LambdaScopeInfo *LSI = dyn_cast<LambdaScopeInfo>(CSI)) {
// For lambda expressions, build a field and an initializing expression,
// and capture the *enclosing object* by copy only if this is the first
// iteration.
ThisExpr = captureThis(*this, Context, LSI->Lambda, ThisTy, CaptureType,
Loc, ByCopy && idx == MaxFunctionScopesIndex);
} else if (CapturedRegionScopeInfo *RSI
= dyn_cast<CapturedRegionScopeInfo>(FunctionScopes[idx]))
ThisExpr = captureThis(*this, Context, RSI->TheRecordDecl, ThisTy,
CaptureType, Loc, false /*ByCopy*/);
bool isNested = NumCapturingClosures > 1;
CSI->addThisCapture(isNested, Loc, CaptureType, ThisExpr, ByCopy);
CSI->addThisCapture(isNested, Loc, CaptureType, ByCopy);
}
return false;
}

23
clang/lib/Sema/SemaLambda.cpp
View File

@ -1431,6 +1431,24 @@ static void addBlockPointerConversion(Sema &S,
Class->addDecl(Conversion);
}
ExprResult Sema::performThisCaptureInitialization(const Capture &Cap,
bool IsImplicit) {
QualType ThisTy = getCurrentThisType();
SourceLocation Loc = Cap.getLocation();
Expr *This = BuildCXXThisExpr(Loc, ThisTy, IsImplicit);
if (Cap.isReferenceCapture())
return This;
// Capture (by copy) of '*this'.
Expr *StarThis = CreateBuiltinUnaryOp(Loc, UO_Deref, This).get();
InitializedEntity Entity = InitializedEntity::InitializeLambdaCapture(
nullptr, Cap.getCaptureType(), Loc);
InitializationKind InitKind =
InitializationKind::CreateDirect(Loc, Loc, Loc);
InitializationSequence Init(*this, Entity, InitKind, StarThis);
return Init.Perform(*this, Entity, InitKind, StarThis);
}
static ExprResult performLambdaVarCaptureInitialization(
Sema &S, const Capture &Capture, FieldDecl *Field,
SourceLocation ImplicitCaptureLoc, bool IsImplicitCapture) {
@ -1680,10 +1698,11 @@ ExprResult Sema::BuildLambdaExpr(SourceLocation StartLoc, SourceLocation EndLoc,
getLocForEndOfToken(CaptureDefaultLoc), ", this");
}
ExprResult Init = performThisCaptureInitialization(From, IsImplicit);
Captures.push_back(
LambdaCapture(From.getLocation(), IsImplicit,
From.isCopyCapture() ? LCK_StarThis : LCK_This));
CaptureInits.push_back(From.getThisInitExpr());
CaptureInits.push_back(Init.get());
continue;
}
if (From.isVLATypeCapture()) {
@ -1703,8 +1722,6 @@ ExprResult Sema::BuildLambdaExpr(SourceLocation StartLoc, SourceLocation EndLoc,
? Var->getInit()
: performLambdaVarCaptureInitialization(
*this, From, Field, CaptureDefaultLoc, IsImplicit);
if (Init.isInvalid())
return ExprError();
CaptureInits.push_back(Init.get());
}

6
clang/lib/Sema/SemaStmt.cpp
View File

@ -4235,9 +4235,11 @@ buildCapturedStmtCaptureList(Sema &S, CapturedRegionScopeInfo *RSI,
FieldDecl *Field = S.BuildCaptureField(RSI->TheRecordDecl, Cap);
if (Cap.isThisCapture()) {
ExprResult Init =
S.performThisCaptureInitialization(Cap, /*Implicit*/ true);
Captures.push_back(CapturedStmt::Capture(Cap.getLocation(),
CapturedStmt::VCK_This));
CaptureInits.push_back(Cap.getThisInitExpr());
CaptureInits.push_back(Init.get());
continue;
} else if (Cap.isVLATypeCapture()) {
Captures.push_back(
@ -4256,8 +4258,6 @@ buildCapturedStmtCaptureList(Sema &S, CapturedRegionScopeInfo *RSI,
// perform a copy here!
ExprResult Init = S.BuildDeclarationNameExpr(
CXXScopeSpec(), DeclarationNameInfo(Var->getDeclName(), Loc), Var);
if (Init.isInvalid())
return true;
Captures.push_back(CapturedStmt::Capture(Loc,
Cap.isReferenceCapture()

6
clang/test/AST/ast-dump-expr-json.cpp
View File

@ -3941,8 +3941,7 @@ void TestNonADLCall3() {
// CHECK-NEXT: "type": {
// CHECK-NEXT: "qualType": "V *"
// CHECK-NEXT: },
// CHECK-NEXT: "valueCategory": "rvalue",
// CHECK-NEXT: "implicit": true
// CHECK-NEXT: "valueCategory": "rvalue"
// CHECK-NEXT: },
// CHECK-NEXT: {
// CHECK-NEXT: "id": "0x{{.*}}",
@ -4173,8 +4172,7 @@ void TestNonADLCall3() {
// CHECK-NEXT: "type": {
// CHECK-NEXT: "qualType": "V *"
// CHECK-NEXT: },
// CHECK-NEXT: "valueCategory": "rvalue",
// CHECK-NEXT: "implicit": true
// CHECK-NEXT: "valueCategory": "rvalue"
// CHECK-NEXT: }
// CHECK-NEXT: ]
// CHECK-NEXT: }

4
clang/test/AST/ast-dump-expr.cpp
View File

@ -255,7 +255,7 @@ void PrimaryExpressions(Ts... a) {
// CHECK-NEXT: CXXMethodDecl
// CHECK-NEXT: CompoundStmt
// CHECK-NEXT: FieldDecl 0x{{[^ ]*}} <col:8> col:8 implicit 'V *'
// CHECK-NEXT: CXXThisExpr 0x{{[^ ]*}} <col:8> 'V *' implicit this
// CHECK-NEXT: CXXThisExpr 0x{{[^ ]*}} <col:8> 'V *' this
[*this]{};
// CHECK: LambdaExpr 0x{{[^ ]*}} <line:[[@LINE-1]]:7, col:15>
@ -272,7 +272,7 @@ void PrimaryExpressions(Ts... a) {
// CHECK-NEXT: FieldDecl 0x{{[^ ]*}} <col:8> col:8 implicit 'V'
// CHECK-NEXT: ParenListExpr 0x{{[^ ]*}} <col:8> 'NULL TYPE'
// CHECK-NEXT: UnaryOperator 0x{{[^ ]*}} <col:8> '<dependent type>' prefix '*' cannot overflow
// CHECK-NEXT: CXXThisExpr 0x{{[^ ]*}} <col:8> 'V *' implicit this
// CHECK-NEXT: CXXThisExpr 0x{{[^ ]*}} <col:8> 'V *' this
}
};

6
clang/test/SemaCXX/lambda-expressions.cpp
View File

@ -105,7 +105,7 @@ namespace SpecialMembers {
a = static_cast<decltype(a)&&>(a); // expected-error {{copy assignment operator is implicitly deleted}}
}
struct P {
P(const P&) = delete; // expected-note {{deleted here}}
P(const P&) = delete; // expected-note 2{{deleted here}}
};
struct Q {
~Q() = delete; // expected-note {{deleted here}}
@ -117,7 +117,9 @@ namespace SpecialMembers {
R &operator=(R&&) = delete;
};
void g(P &p, Q &q, R &r) {
auto pp = [p]{}; // expected-error {{deleted constructor}}
// FIXME: The note attached to the second error here is just amazingly bad.
auto pp = [p]{}; // expected-error {{deleted constructor}} expected-error {{deleted copy constructor of '(lambda}}
// expected-note@-1 {{copy constructor of '' is implicitly deleted because field '' has a deleted copy constructor}}
auto qq = [q]{}; // expected-error {{deleted function}} expected-note {{because}}
auto a = [r]{}; // expected-note 2{{here}}