Recursion-depth-checking fixes

We weren't properly reducing the stack depth when yielding from a generator,
meaning that the recursion depth was effectively decreased by the number
of active generators.

src/runtime/generator.cpp

@@ -360,6 +360,8 @@ static Box* yieldInternal(BoxedGenerator* obj, STOLEN(Box*) value,
                           llvm::ArrayRef<Box*> live_values) noexcept(S == CAPI) {
     STAT_TIMER(t0, "us_timer_generator_switching", 0);
 
+    Py_LeaveRecursiveCall();
+
     assert(obj->cls == generator_cls);
     BoxedGenerator* self = static_cast<BoxedGenerator*>(obj);
     assert(!self->returnValue);
@@ -395,6 +397,15 @@ static Box* yieldInternal(BoxedGenerator* obj, STOLEN(Box*) value,
         ExcInfo e = self->exception;
         self->exception = ExcInfo(NULL, NULL, NULL);
         Py_CLEAR(self->returnValue);
+
+        if (Py_EnterRecursiveCall("resuming generator")) {
+            e.clear();
+            if (S == CAPI)
+                return NULL;
+            else
+                throwCAPIException();
+        }
+
         if (S == CAPI) {
             setCAPIException(e);
             return NULL;
@@ -402,6 +413,14 @@ static Box* yieldInternal(BoxedGenerator* obj, STOLEN(Box*) value,
         throw e;
     }
 
+    if (Py_EnterRecursiveCall("resuming generator")) {
+        Py_CLEAR(self->returnValue);
+        if (S == CAPI)
+            return NULL;
+        else
+            throwCAPIException();
+    }
+
     Box* r = self->returnValue;
     self->returnValue = NULL;
     return r;

src/runtime/objmodel.cpp

@@ -4753,9 +4753,6 @@ Box* callFunc(BoxedFunctionBase* func, CallRewriteArgs* rewrite_args, ArgPassSpe
 template <ExceptionStyle S>
 static Box* callChosenCF(CompiledFunction* chosen_cf, BoxedClosure* closure, BoxedGenerator* generator, Box* globals,
                          Box* oarg1, Box* oarg2, Box* oarg3, Box** oargs) noexcept(S == CAPI) {
-    // TODO: this should go into the emitted code
-    RECURSIVE_BLOCK(S, " in function call");
-
     if (S != chosen_cf->exception_style) {
         if (S == CAPI) {
             try {
@@ -4772,6 +4769,9 @@ static Box* callChosenCF(CompiledFunction* chosen_cf, BoxedClosure* closure, Box
         }
     }
 
+    // TODO: this should go into the emitted code
+    RECURSIVE_BLOCK(S, " in function call");
+
     assert((globals == NULL)
            == (!chosen_cf->code_obj->source || chosen_cf->code_obj->source->scoping.areGlobalsFromModule()));
 

test/tests/generator_recursion_checking.py

+# Some regression tests to make sure recursion-checking works properly with generators
+
+def test(n):
+    l = []
+    for i in xrange(n):
+        g = (i for i in xrange(5))
+        g.next()
+        l.append(g)
+
+for i in xrange(1000):
+    test(3500)