Automatic Reference Counting.
Language-design credit goes to a lot of people, but I particularly want
to single out Blaine Garst and Patrick Beard for their contributions.
Compiler implementation credit goes to Argyrios, Doug, Fariborz, and myself,
in no particular order.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@133103 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index 389dd91..d45ebf9 100644
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -22,6 +22,7 @@
#include "clang/AST/DeclObjC.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/ExprObjC.h"
+#include "clang/AST/EvaluatedExprVisitor.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/StmtCXX.h"
#include "clang/AST/StmtObjC.h"
@@ -382,14 +383,14 @@
// casts here.
// FIXME: We don't allow floating point scalars as input.
Expr *FirstArg = TheCall->getArg(0);
- if (!FirstArg->getType()->isPointerType()) {
+ const PointerType *pointerType = FirstArg->getType()->getAs<PointerType>();
+ if (!pointerType) {
Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer)
<< FirstArg->getType() << FirstArg->getSourceRange();
return ExprError();
}
- QualType ValType =
- FirstArg->getType()->getAs<PointerType>()->getPointeeType();
+ QualType ValType = pointerType->getPointeeType();
if (!ValType->isIntegerType() && !ValType->isAnyPointerType() &&
!ValType->isBlockPointerType()) {
Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer_intptr)
@@ -397,6 +398,20 @@
return ExprError();
}
+ switch (ValType.getObjCLifetime()) {
+ case Qualifiers::OCL_None:
+ case Qualifiers::OCL_ExplicitNone:
+ // okay
+ break;
+
+ case Qualifiers::OCL_Weak:
+ case Qualifiers::OCL_Strong:
+ case Qualifiers::OCL_Autoreleasing:
+ Diag(DRE->getLocStart(), diag::err_arc_atomic_lifetime)
+ << ValType << FirstArg->getSourceRange();
+ return ExprError();
+ }
+
// The majority of builtins return a value, but a few have special return
// types, so allow them to override appropriately below.
QualType ResultType = ValType;
@@ -518,7 +533,8 @@
CastKind Kind = CK_Invalid;
ExprValueKind VK = VK_RValue;
CXXCastPath BasePath;
- Arg = CheckCastTypes(Arg.get()->getSourceRange(), ValType, Arg.take(), Kind, VK, BasePath);
+ Arg = CheckCastTypes(Arg.get()->getLocStart(), Arg.get()->getSourceRange(),
+ ValType, Arg.take(), Kind, VK, BasePath);
if (Arg.isInvalid())
return ExprError();
@@ -1849,6 +1865,7 @@
QualType DestTy = Dest->getType();
if (const PointerType *DestPtrTy = DestTy->getAs<PointerType>()) {
QualType PointeeTy = DestPtrTy->getPointeeType();
+
if (PointeeTy->isVoidType())
continue;
@@ -1863,16 +1880,22 @@
break;
}
+ unsigned DiagID;
+
// Always complain about dynamic classes.
- if (isDynamicClassType(PointeeTy)) {
- DiagRuntimeBehavior(
- Dest->getExprLoc(), Dest,
- PDiag(diag::warn_dyn_class_memaccess)
- << ArgIdx << FnName << PointeeTy
- << Call->getCallee()->getSourceRange());
- } else {
+ if (isDynamicClassType(PointeeTy))
+ DiagID = diag::warn_dyn_class_memaccess;
+ else if (PointeeTy.hasNonTrivialObjCLifetime() &&
+ !FnName->isStr("memset"))
+ DiagID = diag::warn_arc_object_memaccess;
+ else
continue;
- }
+
+ DiagRuntimeBehavior(
+ Dest->getExprLoc(), Dest,
+ PDiag(DiagID)
+ << ArgIdx << FnName << PointeeTy
+ << Call->getCallee()->getSourceRange());
DiagRuntimeBehavior(
Dest->getExprLoc(), Dest,
@@ -1899,7 +1922,8 @@
// Perform checking for returned stack addresses, local blocks,
// label addresses or references to temporaries.
- if (lhsType->isPointerType() || lhsType->isBlockPointerType()) {
+ if (lhsType->isPointerType() ||
+ (!getLangOptions().ObjCAutoRefCount && lhsType->isBlockPointerType())) {
stackE = EvalAddr(RetValExp, refVars);
} else if (lhsType->isReferenceType()) {
stackE = EvalVal(RetValExp, refVars);
@@ -2070,7 +2094,8 @@
// pointer values, and pointer-to-pointer conversions.
case Stmt::ImplicitCastExprClass:
case Stmt::CStyleCastExprClass:
- case Stmt::CXXFunctionalCastExprClass: {
+ case Stmt::CXXFunctionalCastExprClass:
+ case Stmt::ObjCBridgedCastExprClass: {
Expr* SubExpr = cast<CastExpr>(E)->getSubExpr();
QualType T = SubExpr->getType();
@@ -3385,3 +3410,232 @@
}
}
}
+
+//===--- CHECK: Objective-C retain cycles ----------------------------------//
+
+namespace {
+ struct RetainCycleOwner {
+ RetainCycleOwner() : Variable(0), Indirect(false) {}
+ VarDecl *Variable;
+ SourceRange Range;
+ SourceLocation Loc;
+ bool Indirect;
+
+ void setLocsFrom(Expr *e) {
+ Loc = e->getExprLoc();
+ Range = e->getSourceRange();
+ }
+ };
+}
+
+/// Consider whether capturing the given variable can possibly lead to
+/// a retain cycle.
+static bool considerVariable(VarDecl *var, Expr *ref, RetainCycleOwner &owner) {
+ // In ARC, it's captured strongly iff the variable has __strong
+ // lifetime. In MRR, it's captured strongly if the variable is
+ // __block and has an appropriate type.
+ if (var->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
+ return false;
+
+ owner.Variable = var;
+ owner.setLocsFrom(ref);
+ return true;
+}
+
+static bool findRetainCycleOwner(Expr *e, RetainCycleOwner &owner) {
+ while (true) {
+ e = e->IgnoreParens();
+ if (CastExpr *cast = dyn_cast<CastExpr>(e)) {
+ switch (cast->getCastKind()) {
+ case CK_BitCast:
+ case CK_LValueBitCast:
+ case CK_LValueToRValue:
+ e = cast->getSubExpr();
+ continue;
+
+ case CK_GetObjCProperty: {
+ // Bail out if this isn't a strong explicit property.
+ const ObjCPropertyRefExpr *pre = cast->getSubExpr()->getObjCProperty();
+ if (pre->isImplicitProperty()) return false;
+ ObjCPropertyDecl *property = pre->getExplicitProperty();
+ if (!(property->getPropertyAttributes() &
+ (ObjCPropertyDecl::OBJC_PR_retain |
+ ObjCPropertyDecl::OBJC_PR_copy |
+ ObjCPropertyDecl::OBJC_PR_strong)) &&
+ !(property->getPropertyIvarDecl() &&
+ property->getPropertyIvarDecl()->getType()
+ .getObjCLifetime() == Qualifiers::OCL_Strong))
+ return false;
+
+ owner.Indirect = true;
+ e = const_cast<Expr*>(pre->getBase());
+ continue;
+ }
+
+ default:
+ return false;
+ }
+ }
+
+ if (ObjCIvarRefExpr *ref = dyn_cast<ObjCIvarRefExpr>(e)) {
+ ObjCIvarDecl *ivar = ref->getDecl();
+ if (ivar->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
+ return false;
+
+ // Try to find a retain cycle in the base.
+ if (!findRetainCycleOwner(ref->getBase(), owner))
+ return false;
+
+ if (ref->isFreeIvar()) owner.setLocsFrom(ref);
+ owner.Indirect = true;
+ return true;
+ }
+
+ if (DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e)) {
+ VarDecl *var = dyn_cast<VarDecl>(ref->getDecl());
+ if (!var) return false;
+ return considerVariable(var, ref, owner);
+ }
+
+ if (BlockDeclRefExpr *ref = dyn_cast<BlockDeclRefExpr>(e)) {
+ owner.Variable = ref->getDecl();
+ owner.setLocsFrom(ref);
+ return true;
+ }
+
+ if (MemberExpr *member = dyn_cast<MemberExpr>(e)) {
+ if (member->isArrow()) return false;
+
+ // Don't count this as an indirect ownership.
+ e = member->getBase();
+ continue;
+ }
+
+ // Array ivars?
+
+ return false;
+ }
+}
+
+namespace {
+ struct FindCaptureVisitor : EvaluatedExprVisitor<FindCaptureVisitor> {
+ FindCaptureVisitor(ASTContext &Context, VarDecl *variable)
+ : EvaluatedExprVisitor<FindCaptureVisitor>(Context),
+ Variable(variable), Capturer(0) {}
+
+ VarDecl *Variable;
+ Expr *Capturer;
+
+ void VisitDeclRefExpr(DeclRefExpr *ref) {
+ if (ref->getDecl() == Variable && !Capturer)
+ Capturer = ref;
+ }
+
+ void VisitBlockDeclRefExpr(BlockDeclRefExpr *ref) {
+ if (ref->getDecl() == Variable && !Capturer)
+ Capturer = ref;
+ }
+
+ void VisitObjCIvarRefExpr(ObjCIvarRefExpr *ref) {
+ if (Capturer) return;
+ Visit(ref->getBase());
+ if (Capturer && ref->isFreeIvar())
+ Capturer = ref;
+ }
+
+ void VisitBlockExpr(BlockExpr *block) {
+ // Look inside nested blocks
+ if (block->getBlockDecl()->capturesVariable(Variable))
+ Visit(block->getBlockDecl()->getBody());
+ }
+ };
+}
+
+/// Check whether the given argument is a block which captures a
+/// variable.
+static Expr *findCapturingExpr(Sema &S, Expr *e, RetainCycleOwner &owner) {
+ assert(owner.Variable && owner.Loc.isValid());
+
+ e = e->IgnoreParenCasts();
+ BlockExpr *block = dyn_cast<BlockExpr>(e);
+ if (!block || !block->getBlockDecl()->capturesVariable(owner.Variable))
+ return 0;
+
+ FindCaptureVisitor visitor(S.Context, owner.Variable);
+ visitor.Visit(block->getBlockDecl()->getBody());
+ return visitor.Capturer;
+}
+
+static void diagnoseRetainCycle(Sema &S, Expr *capturer,
+ RetainCycleOwner &owner) {
+ assert(capturer);
+ assert(owner.Variable && owner.Loc.isValid());
+
+ S.Diag(capturer->getExprLoc(), diag::warn_arc_retain_cycle)
+ << owner.Variable << capturer->getSourceRange();
+ S.Diag(owner.Loc, diag::note_arc_retain_cycle_owner)
+ << owner.Indirect << owner.Range;
+}
+
+/// Check for a keyword selector that starts with the word 'add' or
+/// 'set'.
+static bool isSetterLikeSelector(Selector sel) {
+ if (sel.isUnarySelector()) return false;
+
+ llvm::StringRef str = sel.getNameForSlot(0);
+ while (!str.empty() && str.front() == '_') str = str.substr(1);
+ if (str.startswith("set") || str.startswith("add"))
+ str = str.substr(3);
+ else
+ return false;
+
+ if (str.empty()) return true;
+ return !islower(str.front());
+}
+
+/// Check a message send to see if it's likely to cause a retain cycle.
+void Sema::checkRetainCycles(ObjCMessageExpr *msg) {
+ // Only check instance methods whose selector looks like a setter.
+ if (!msg->isInstanceMessage() || !isSetterLikeSelector(msg->getSelector()))
+ return;
+
+ // Try to find a variable that the receiver is strongly owned by.
+ RetainCycleOwner owner;
+ if (msg->getReceiverKind() == ObjCMessageExpr::Instance) {
+ if (!findRetainCycleOwner(msg->getInstanceReceiver(), owner))
+ return;
+ } else {
+ assert(msg->getReceiverKind() == ObjCMessageExpr::SuperInstance);
+ owner.Variable = getCurMethodDecl()->getSelfDecl();
+ owner.Loc = msg->getSuperLoc();
+ owner.Range = msg->getSuperLoc();
+ }
+
+ // Check whether the receiver is captured by any of the arguments.
+ for (unsigned i = 0, e = msg->getNumArgs(); i != e; ++i)
+ if (Expr *capturer = findCapturingExpr(*this, msg->getArg(i), owner))
+ return diagnoseRetainCycle(*this, capturer, owner);
+}
+
+/// Check a property assign to see if it's likely to cause a retain cycle.
+void Sema::checkRetainCycles(Expr *receiver, Expr *argument) {
+ RetainCycleOwner owner;
+ if (!findRetainCycleOwner(receiver, owner))
+ return;
+
+ if (Expr *capturer = findCapturingExpr(*this, argument, owner))
+ diagnoseRetainCycle(*this, capturer, owner);
+}
+
+void Sema::checkUnsafeAssigns(SourceLocation Loc,
+ QualType LHS, Expr *RHS) {
+ Qualifiers::ObjCLifetime LT = LHS.getObjCLifetime();
+ if (LT != Qualifiers::OCL_Weak && LT != Qualifiers::OCL_ExplicitNone)
+ return;
+ if (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS))
+ if (cast->getCastKind() == CK_ObjCConsumeObject)
+ Diag(Loc, diag::warn_arc_retained_assign)
+ << (LT == Qualifiers::OCL_ExplicitNone)
+ << RHS->getSourceRange();
+}
+