we're already unmapping the redzone as part of the munmap() call. also, free...

we're already unmapping the redzone as part of the munmap() call.  also, free the generator stack from the sending side, not from within the generator.

src/runtime/generator.cpp

@@ -71,13 +71,6 @@ static void freeGeneratorStack(BoxedGenerator* g) {
         available_addrs.pop_front();
         int r = munmap((void*)(addr - MAX_STACK_SIZE), MAX_STACK_SIZE);
         assert(r == 0);
-// also unmap the redzone
-#if STACK_GROWS_DOWN
-        r = munmap((void*)addr, STACK_REDZONE_SIZE);
-        assert(r == 0);
-#else
-#error "implement me"
-#endif
     }
 
     g->stack_begin = NULL;
@@ -111,7 +104,6 @@ void generatorEntry(BoxedGenerator* g) {
     // we returned from the body of the generator. next/send/throw will notify the caller
     g->entryExited = true;
     threading::popGenerator();
-    freeGeneratorStack(g);
     swapContext(&g->context, g->returnContext, 0);
 }
 
@@ -127,8 +119,10 @@ Box* generatorSend(Box* s, Box* v) {
         raiseExcHelper(ValueError, "generator already executing");
 
     // check if the generator already exited
-    if (self->entryExited)
+    if (self->entryExited) {
+        freeGeneratorStack(self);
         raiseExcHelper(StopIteration, "");
+    }
 
     self->returnValue = v;
     self->running = true;
@@ -136,12 +130,16 @@ Box* generatorSend(Box* s, Box* v) {
     self->running = false;
 
     // propagate exception to the caller
-    if (self->exception.type)
+    if (self->exception.type) {
+        freeGeneratorStack(self);
         raiseRaw(self->exception);
+    }
 
     // throw StopIteration if the generator exited
-    if (self->entryExited)
+    if (self->entryExited) {
+        freeGeneratorStack(self);
         raiseExcHelper(StopIteration, "");
+    }
 
     return self->returnValue;
 }