objective-C arc: load of a __weak object happens via call to
objc_loadWeak. This retains and autorelease the weakly-refereced
object. This hidden autorelease sometimes makes __weak variable alive even
after the weak reference is erased, because the object is still referenced
by an autorelease pool. This patch overcomes this behavior by loading a
weak object via call to objc_loadWeakRetained(), followng it by objc_release
at appropriate place, thereby removing the hidden autorelease. // rdar://10849570
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@168740 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaInit.cpp b/lib/Sema/SemaInit.cpp
index 7ed3942..5b7fb46 100644
--- a/lib/Sema/SemaInit.cpp
+++ b/lib/Sema/SemaInit.cpp
@@ -3846,14 +3846,15 @@
/// Determines whether this expression is an acceptable ICR source.
static InvalidICRKind isInvalidICRSource(ASTContext &C, Expr *e,
- bool isAddressOf) {
+ bool isAddressOf, bool &isWeakAccess) {
// Skip parens.
e = e->IgnoreParens();
// Skip address-of nodes.
if (UnaryOperator *op = dyn_cast<UnaryOperator>(e)) {
if (op->getOpcode() == UO_AddrOf)
- return isInvalidICRSource(C, op->getSubExpr(), /*addressof*/ true);
+ return isInvalidICRSource(C, op->getSubExpr(), /*addressof*/ true,
+ isWeakAccess);
// Skip certain casts.
} else if (CastExpr *ce = dyn_cast<CastExpr>(e)) {
@@ -3862,7 +3863,7 @@
case CK_BitCast:
case CK_LValueBitCast:
case CK_NoOp:
- return isInvalidICRSource(C, ce->getSubExpr(), isAddressOf);
+ return isInvalidICRSource(C, ce->getSubExpr(), isAddressOf, isWeakAccess);
case CK_ArrayToPointerDecay:
return IIK_nonscalar;
@@ -3876,6 +3877,11 @@
// If we have a declaration reference, it had better be a local variable.
} else if (isa<DeclRefExpr>(e)) {
+ // set isWeakAccess to true, to mean that there will be an implicit
+ // load which requires a cleanup.
+ if (e->getType().getObjCLifetime() == Qualifiers::OCL_Weak)
+ isWeakAccess = true;
+
if (!isAddressOf) return IIK_nonlocal;
VarDecl *var = dyn_cast<VarDecl>(cast<DeclRefExpr>(e)->getDecl());
@@ -3885,10 +3891,11 @@
// If we have a conditional operator, check both sides.
} else if (ConditionalOperator *cond = dyn_cast<ConditionalOperator>(e)) {
- if (InvalidICRKind iik = isInvalidICRSource(C, cond->getLHS(), isAddressOf))
+ if (InvalidICRKind iik = isInvalidICRSource(C, cond->getLHS(), isAddressOf,
+ isWeakAccess))
return iik;
- return isInvalidICRSource(C, cond->getRHS(), isAddressOf);
+ return isInvalidICRSource(C, cond->getRHS(), isAddressOf, isWeakAccess);
// These are never scalar.
} else if (isa<ArraySubscriptExpr>(e)) {
@@ -3907,8 +3914,13 @@
/// indirect copy/restore.
static void checkIndirectCopyRestoreSource(Sema &S, Expr *src) {
assert(src->isRValue());
-
- InvalidICRKind iik = isInvalidICRSource(S.Context, src, false);
+ bool isWeakAccess = false;
+ InvalidICRKind iik = isInvalidICRSource(S.Context, src, false, isWeakAccess);
+ // If isWeakAccess to true, there will be an implicit
+ // load which requires a cleanup.
+ if (S.getLangOpts().ObjCAutoRefCount && isWeakAccess)
+ S.ExprNeedsCleanups = true;
+
if (iik == IIK_okay) return;
S.Diag(src->getExprLoc(), diag::err_arc_nonlocal_writeback)