[CodeGen][ObjC] Extend lifetime of ObjC pointers passed to calls to
__builtin_os_log_format
This is needed to keep all the objects, including temporaries returned
by function calls, written to the buffer alive until os_log_pack_send is
called.
rdar://problem/60105410
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 417b308..952cc3f 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -1320,14 +1320,30 @@
} else if (const Expr *TheExpr = Item.getExpr()) {
ArgVal = EmitScalarExpr(TheExpr, /*Ignore*/ false);
- // Check if this is a retainable type.
+ // If this is a retainable type, push a lifetime-extended cleanup to
+ // ensure the lifetime of the argument is extended to the end of the
+ // enclosing block scope.
+ // FIXME: We only have to do this if the argument is a temporary, which
+ // gets released after the full expression.
if (TheExpr->getType()->isObjCRetainableType()) {
assert(getEvaluationKind(TheExpr->getType()) == TEK_Scalar &&
"Only scalar can be a ObjC retainable type");
- // Check if the object is constant, if not, save it in
- // RetainableOperands.
- if (!isa<Constant>(ArgVal))
- RetainableOperands.push_back(ArgVal);
+ if (!isa<Constant>(ArgVal)) {
+ CleanupKind Cleanup = getARCCleanupKind();
+ QualType Ty = TheExpr->getType();
+ Address Alloca = Address::invalid();
+ Address Addr = CreateMemTemp(Ty, "os.log.arg", &Alloca);
+ ArgVal = EmitARCRetain(Ty, ArgVal);
+ Builder.CreateStore(ArgVal, Addr);
+ pushLifetimeExtendedDestroy(Cleanup, Alloca, Ty,
+ CodeGenFunction::destroyARCStrongPrecise,
+ Cleanup & EHCleanup);
+
+ // Push a clang.arc.use call to ensure ARC optimizer knows that the
+ // argument has to be alive.
+ if (CGM.getCodeGenOpts().OptimizationLevel != 0)
+ pushCleanupAfterFullExpr<CallObjCArcUse>(Cleanup, ArgVal);
+ }
}
} else {
ArgVal = Builder.getInt32(Item.getConstValue().getQuantity());
@@ -1349,18 +1365,6 @@
llvm::Function *F = CodeGenFunction(CGM).generateBuiltinOSLogHelperFunction(
Layout, BufAddr.getAlignment());
EmitCall(FI, CGCallee::forDirect(F), ReturnValueSlot(), Args);
-
- // Push a clang.arc.use cleanup for each object in RetainableOperands. The
- // cleanup will cause the use to appear after the final log call, keeping
- // the object valid while it’s held in the log buffer. Note that if there’s
- // a release cleanup on the object, it will already be active; since
- // cleanups are emitted in reverse order, the use will occur before the
- // object is released.
- if (!RetainableOperands.empty() && getLangOpts().ObjCAutoRefCount &&
- CGM.getCodeGenOpts().OptimizationLevel != 0)
- for (llvm::Value *Object : RetainableOperands)
- pushFullExprCleanup<CallObjCArcUse>(getARCCleanupKind(), Object);
-
return RValue::get(BufAddr.getPointer());
}