Make this a bit easier

src/runtime/capi.cpp

@@ -1718,7 +1718,6 @@ template <ExceptionStyle S>
 Box* BoxedCApiFunction::tppCall(Box* _self, CallRewriteArgs* rewrite_args, ArgPassSpec argspec, Box* arg1, Box* arg2,
                                 Box* arg3, Box** args,
                                 const std::vector<BoxedString*>* keyword_names) noexcept(S == CAPI) {
-    assert(0 && "check refcounting");
     if (S == CAPI) {
         try {
             return tppCall<CXX>(_self, NULL, argspec, arg1, arg2, arg3, args, keyword_names);
@@ -1806,6 +1805,8 @@ Box* BoxedCApiFunction::tppCall(Box* _self, CallRewriteArgs* rewrite_args, ArgPa
     rearrangeArguments(paramspec, NULL, self->method_def->ml_name, defaults, rewrite_args, rewrite_success, argspec,
                        arg1, arg2, arg3, args, oargs, keyword_names);
 
+    AUTO_DECREF_ARGS(paramspec, arg1, arg2, arg3, oargs);
+
     if (!rewrite_success)
         rewrite_args = NULL;
 
@@ -1870,25 +1871,11 @@ Box* BoxedCApiFunction::tppCall(Box* _self, CallRewriteArgs* rewrite_args, ArgPa
         RELEASE_ASSERT(0, "0x%x", flags);
     }
 
-    assert(paramspec.totalReceived() <= 3);
-    assert(!oargs);
-
     if (rewrite_args) {
         rewrite_args->rewriter->checkAndThrowCAPIException(rewrite_args->out_rtn);
         rewrite_args->out_success = true;
     }
 
-    switch (paramspec.totalReceived()) {
-        case 3:
-            Py_XDECREF(arg3);
-        case 2:
-            Py_XDECREF(arg2);
-        case 1:
-            Py_XDECREF(arg1);
-        default:
-            break;
-    }
-
     checkAndThrowCAPIException();
     assert(rtn && "should have set + thrown an exception!");
     return rtn;

src/runtime/descr.cpp

@@ -247,7 +247,6 @@ template <ExceptionStyle S>
 Box* BoxedMethodDescriptor::tppCall(Box* _self, CallRewriteArgs* rewrite_args, ArgPassSpec argspec, Box* arg1,
                                     Box* arg2, Box* arg3, Box** args,
                                     const std::vector<BoxedString*>* keyword_names) noexcept(S == CAPI) {
-    assert(0 && "check refcounting");
     if (S == CAPI) {
         try {
             return tppCall<CXX>(_self, NULL, argspec, arg1, arg2, arg3, args, keyword_names);
@@ -314,6 +313,8 @@ Box* BoxedMethodDescriptor::tppCall(Box* _self, CallRewriteArgs* rewrite_args, A
     rearrangeArguments(paramspec, NULL, self->method->ml_name, defaults, rewrite_args, rewrite_success, argspec, arg1,
                        arg2, arg3, args, oargs, keyword_names);
 
+    AUTO_DECREF_ARGS(paramspec, arg1, arg2, arg3, oargs);
+
     if (!rewrite_success)
         rewrite_args = NULL;
 
@@ -394,15 +395,6 @@ Box* BoxedMethodDescriptor::tppCall(Box* _self, CallRewriteArgs* rewrite_args, A
         RELEASE_ASSERT(0, "0x%x", call_flags);
     }
 
-    if (paramspec.totalReceived() >= 1)
-        Py_DECREF(arg1);
-    if (paramspec.totalReceived() >= 2)
-        Py_DECREF(arg2);
-    if (paramspec.totalReceived() >= 3)
-        Py_DECREF(arg3);
-    for (int i = 0; i < paramspec.totalReceived() - 3; i++)
-        Py_DECREF(oargs[i]);
-
     if (!rtn)
         throwCAPIException();
 
@@ -602,7 +594,6 @@ template <ExceptionStyle S>
 Box* BoxedWrapperDescriptor::tppCall(Box* _self, CallRewriteArgs* rewrite_args, ArgPassSpec argspec, Box* arg1,
                                      Box* arg2, Box* arg3, Box** args,
                                      const std::vector<BoxedString*>* keyword_names) noexcept(S == CAPI) {
-    assert(0 && "Check refcounting");
     if (S == CAPI) {
         try {
             return tppCall<CXX>(_self, NULL, argspec, arg1, arg2, arg3, args, keyword_names);
@@ -640,6 +631,8 @@ Box* BoxedWrapperDescriptor::tppCall(Box* _self, CallRewriteArgs* rewrite_args,
     rearrangeArguments(paramspec, NULL, self->wrapper->name.data(), NULL, rewrite_args, rewrite_success, argspec, arg1,
                        arg2, arg3, args, oargs, keyword_names);
 
+    AUTO_DECREF_ARGS(paramspec, arg1, arg2, arg3, oargs);
+
     if (paramspec.takes_varargs)
         assert(arg2 && arg2->cls == tuple_cls);
 
@@ -697,20 +690,6 @@ Box* BoxedWrapperDescriptor::tppCall(Box* _self, CallRewriteArgs* rewrite_args,
         RELEASE_ASSERT(0, "%d", flags);
     }
 
-    assert(paramspec.totalReceived() <= 3);
-    assert(!oargs);
-
-    switch (paramspec.totalReceived()) {
-        case 3:
-            Py_XDECREF(arg3);
-        case 2:
-            Py_XDECREF(arg2);
-        case 1:
-            Py_XDECREF(arg1);
-        default:
-            break;
-    }
-
     if (!rtn)
         throwCAPIException();
     return rtn;

src/runtime/types.cpp

@@ -570,7 +570,6 @@ static Box* typeCallInner(CallRewriteArgs* rewrite_args, ArgPassSpec argspec, Bo
 template <ExceptionStyle S>
 static Box* typeTppCall(Box* self, CallRewriteArgs* rewrite_args, ArgPassSpec argspec, Box* arg1, Box* arg2, Box* arg3,
                         Box** args, const std::vector<BoxedString*>* keyword_names) noexcept(S == CAPI) {
-    assert(0 && "check refcounting");
     int npassed_args = argspec.totalPassed();
 
     // Common CAPI path call this function with *args, **kw.
@@ -585,9 +584,9 @@ static Box* typeTppCall(Box* self, CallRewriteArgs* rewrite_args, ArgPassSpec ar
             else
                 throwCAPIException();
         }
+        AUTO_DECREF(arg1);
 
         Box* r = cpython_type_call(static_cast<BoxedClass*>(self), arg1, argspec.has_kwargs ? arg2 : NULL);
-        Py_DECREF(arg1);
         if (S == CXX && !r)
             throwCAPIException();
         return r;
@@ -718,7 +717,6 @@ static Box* objectNewNoArgs(BoxedClass* cls) noexcept {
 template <ExceptionStyle S>
 static Box* typeCallInner(CallRewriteArgs* rewrite_args, ArgPassSpec argspec, Box* arg1, Box* arg2, Box* arg3,
                           Box** args, const std::vector<BoxedString*>* keyword_names) noexcept(S == CAPI) {
-    assert(0 && "check refcounting");
     int npassed_args = argspec.totalPassed();
     int npositional = argspec.num_args;
 
@@ -761,10 +759,13 @@ static Box* typeCallInner(CallRewriteArgs* rewrite_args, ArgPassSpec argspec, Bo
         static Box* defaults[3] = { NULL, NULL, NULL };
         Box* oargs[1];
 
+
         rearrangeArguments(paramspec, &param_names, "unicode", defaults, rewrite_args, rewrite_success, argspec, arg1,
                            arg2, arg3, args, oargs, keyword_names);
         assert(arg1 == cls);
 
+        AUTO_DECREF_ARGS(paramspec, arg1, arg2, arg3, oargs);
+
         if (!rewrite_success)
             rewrite_args = NULL;
 
@@ -1126,8 +1127,8 @@ static Box* typeCallInner(CallRewriteArgs* rewrite_args, ArgPassSpec argspec, Bo
                 throw e;
         }
 
-        AUTO_XDECREF(made);
-        AUTO_XDECREF(arg2);
+        AUTO_DECREF(made);
+        AUTO_DECREF(arg2);
         AUTO_XDECREF(arg3);
 
         if (!rewrite_success)

src/runtime/types.h

@@ -398,6 +398,40 @@ public:
 #define AUTO_DECREF_ARRAY(x, size) AutoDecrefArray<false> CAT(_autodecref_, __LINE__)((x), (size))
 #define AUTO_XDECREF_ARRAY(x, size) AutoDecrefArray<true> CAT(_autodecref_, __LINE__)((x), (size))
 
+class AutoDecrefArgs {
+private:
+    int num_args;
+    Box* arg1, *arg2, *arg3;
+    Box** args;
+
+public:
+    AutoDecrefArgs(int num_args, Box* arg1, Box* arg2, Box* arg3, Box** args)
+        : num_args(num_args), arg1(arg1), arg2(arg2), arg3(arg3), args(args) {}
+    AutoDecrefArgs(ParamReceiveSpec paramspec, Box* arg1, Box* arg2, Box* arg3, Box** args)
+        : num_args(paramspec.totalReceived()), arg1(arg1), arg2(arg2), arg3(arg3), args(args) {}
+
+    ~AutoDecrefArgs() {
+        // TODO Minor optimization: only the last arg (kwargs) is allowed to be NULL.
+        switch (num_args) {
+            default:
+                for (int i = 0; i < num_args - 3; i++) {
+                    Py_XDECREF(args[i]);
+                }
+            case 3:
+                Py_XDECREF(arg3);
+            case 2:
+                Py_XDECREF(arg2);
+            case 1:
+                Py_XDECREF(arg1);
+            case 0:
+                break;
+        }
+    }
+};
+// Note: this captures the first three args by value (like AUTO_DECREF) but the array by reference.
+// You can also pass a ParamReceiveSpec instead of an int for num_args
+#define AUTO_DECREF_ARGS(num_args, arg1, arg2, arg3, args) AutoDecrefArgs CAT(_autodecref_, __LINE__)((num_args), (arg1), (arg2), (arg3), (args))
+
 template <typename B> B* incref(B* b) {
     Py_INCREF(b);
     return b;