objgenerator: Implement .throw() method to throw exceptions into generator.

1 files changed, 14 insertions, 6 deletions

diff --git a/py/vm.c b/py/vm.c
index 1afd8363d1..7f4efeea0f 100644
--- a/py/vm.c
+++ b/py/vm.c
@@ -82,7 +82,7 @@ mp_vm_return_kind_t mp_execute_byte_code(const byte *code, const mp_obj_t *args,
     mp_exc_stack exc_stack[4];
     mp_exc_stack *exc_sp = &exc_stack[0] - 1;
     // execute the byte code
-    mp_vm_return_kind_t vm_return_kind = mp_execute_byte_code_2(code, &ip, &state[n_state - 1], &sp, exc_stack, &exc_sp);
+    mp_vm_return_kind_t vm_return_kind = mp_execute_byte_code_2(code, &ip, &state[n_state - 1], &sp, exc_stack, &exc_sp, MP_OBJ_NULL);
 
     switch (vm_return_kind) {
         case MP_VM_RETURN_NORMAL:
@@ -107,8 +107,8 @@ mp_vm_return_kind_t mp_execute_byte_code(const byte *code, const mp_obj_t *args,
 //  MP_VM_RETURN_EXCEPTION, exception in fastn[0]
 mp_vm_return_kind_t mp_execute_byte_code_2(const byte *code_info, const byte **ip_in_out,
                                            mp_obj_t *fastn, mp_obj_t **sp_in_out,
-                                           mp_exc_stack *exc_stack,
-                                           mp_exc_stack **exc_sp_in_out) {
+                                           mp_exc_stack *exc_stack, mp_exc_stack **exc_sp_in_out,
+                                           volatile mp_obj_t inject_exc) {
     // careful: be sure to declare volatile any variables read in the exception handler (written is ok, I think)
 
     const byte *ip = *ip_in_out;
@@ -118,13 +118,21 @@ mp_vm_return_kind_t mp_execute_byte_code_2(const byte *code_info, const byte **i
     mp_obj_t obj1, obj2;
     nlr_buf_t nlr;
 
-    volatile machine_uint_t currently_in_except_block = 0; // 0 or 1, to detect nested exceptions
-    mp_exc_stack *volatile exc_sp = *exc_sp_in_out; // stack grows up, exc_sp points to top of stack
+    volatile machine_uint_t currently_in_except_block = (int)*exc_sp_in_out & 1; // 0 or 1, to detect nested exceptions
+    mp_exc_stack *volatile exc_sp = (void*)((int)*exc_sp_in_out & ~1); // stack grows up, exc_sp points to top of stack
     const byte *volatile save_ip = ip; // this is so we can access ip in the exception handler without making ip volatile (which means the compiler can't keep it in a register in the main loop)
 
     // outer exception handling loop
     for (;;) {
         if (nlr_push(&nlr) == 0) {
+            // If we have exception to inject, now that we finish setting up
+            // execution context, raise it. This works as if RAISE_VARARGS
+            // bytecode was executed.
+            if (inject_exc != MP_OBJ_NULL) {
+                mp_obj_t t = inject_exc;
+                inject_exc = MP_OBJ_NULL;
+                nlr_jump(rt_make_raise_obj(t));
+            }
             // loop to execute byte code
             for (;;) {
 dispatch_loop:
@@ -599,7 +607,7 @@ unwind_return:
                         nlr_pop();
                         *ip_in_out = ip;
                         *sp_in_out = sp;
-                        *exc_sp_in_out = exc_sp;
+                        *exc_sp_in_out = (void*)((int)exc_sp | currently_in_except_block);
                         return MP_VM_RETURN_YIELD;
 
                     case MP_BC_IMPORT_NAME: