From c0abc28aa1211204c589b9e8062d7c2874b5f083 Mon Sep 17 00:00:00 2001 From: Paul Sokolovsky Date: Sat, 22 Mar 2014 13:49:31 +0200 Subject: [PATCH] objgenerator: Keep exception stack within generator object, like value stack. This is required to properly handle exceptions across yields. --- py/bc.h | 12 +++++++++++- py/objgenerator.c | 11 ++++++++--- py/vm.c | 33 ++++++++++++++------------------- tests/basics/generator-exc.py | 11 +++++++++++ 4 files changed, 44 insertions(+), 23 deletions(-) create mode 100644 tests/basics/generator-exc.py diff --git a/py/bc.h b/py/bc.h index aac35954d7..d13295b3bd 100644 --- a/py/bc.h +++ b/py/bc.h @@ -4,6 +4,16 @@ typedef enum { MP_VM_RETURN_EXCEPTION, } mp_vm_return_kind_t; +// Exception stack entry +typedef struct _mp_exc_stack { + const byte *handler; + // bit 0 is saved currently_in_except_block value + machine_uint_t val_sp; + // We might only have 2 interesting cases here: SETUP_EXCEPT & SETUP_FINALLY, + // consider storing it in bit 1 of val_sp. TODO: SETUP_WITH? + byte opcode; +} mp_exc_stack; + mp_vm_return_kind_t mp_execute_byte_code(const byte *code, const mp_obj_t *args, uint n_args, const mp_obj_t *args2, uint n_args2, uint n_state, mp_obj_t *ret); -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_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); void mp_byte_code_print(const byte *code, int len); diff --git a/py/objgenerator.c b/py/objgenerator.c index 8c4bb595f1..fd7329fb0b 100644 --- a/py/objgenerator.c +++ b/py/objgenerator.c @@ -56,8 +56,10 @@ typedef struct _mp_obj_gen_instance_t { const byte *code_info; const byte *ip; mp_obj_t *sp; + mp_exc_stack *exc_sp; uint n_state; - mp_obj_t state[]; + mp_obj_t state[0]; // Variable-length + mp_exc_stack exc_state[0]; // Variable-length } mp_obj_gen_instance_t; void gen_instance_print(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t self_in, mp_print_kind_t kind) { @@ -80,7 +82,8 @@ STATIC mp_obj_t gen_next_send(mp_obj_t self_in, mp_obj_t send_value) { } else { *self->sp = send_value; } - mp_vm_return_kind_t vm_return_kind = mp_execute_byte_code_2(self->code_info, &self->ip, &self->state[self->n_state - 1], &self->sp); + mp_vm_return_kind_t vm_return_kind = mp_execute_byte_code_2(self->code_info, &self->ip, + &self->state[self->n_state - 1], &self->sp, (mp_exc_stack*)(self->state + self->n_state), &self->exc_sp); switch (vm_return_kind) { case MP_VM_RETURN_NORMAL: // Explicitly mark generator as completed. If we don't do this, @@ -137,11 +140,13 @@ const mp_obj_type_t gen_instance_type = { }; mp_obj_t mp_obj_new_gen_instance(const byte *bytecode, uint n_state, int n_args, const mp_obj_t *args) { - mp_obj_gen_instance_t *o = m_new_obj_var(mp_obj_gen_instance_t, mp_obj_t, n_state); + // TODO: 4 is hardcoded number from vm.c, calc exc stack size instead. + mp_obj_gen_instance_t *o = m_new_obj_var(mp_obj_gen_instance_t, byte, n_state * sizeof(mp_obj_t) + 4 * sizeof(mp_exc_stack)); o->base.type = &gen_instance_type; o->code_info = bytecode; o->ip = bytecode; o->sp = &o->state[0] - 1; // sp points to top of stack, which starts off 1 below the state + o->exc_sp = (mp_exc_stack*)(o->state + n_state) - 1; o->n_state = n_state; // copy args to end of state array, in reverse (that's how mp_execute_byte_code_2 needs it) diff --git a/py/vm.c b/py/vm.c index 7b78b5fefb..1afd8363d1 100644 --- a/py/vm.c +++ b/py/vm.c @@ -17,16 +17,6 @@ // top element. // Exception stack also grows up, top element is also pointed at. -// Exception stack entry -typedef struct _mp_exc_stack { - const byte *handler; - // bit 0 is saved currently_in_except_block value - machine_uint_t val_sp; - // We might only have 2 interesting cases here: SETUP_EXCEPT & SETUP_FINALLY, - // consider storing it in bit 1 of val_sp. TODO: SETUP_WITH? - byte opcode; -} mp_exc_stack; - // Exception stack unwind reasons (WHY_* in CPython-speak) // TODO perhaps compress this to RETURN=0, JUMP>0, with number of unwinds // left to do encoded in the JUMP number @@ -89,8 +79,10 @@ 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); + mp_vm_return_kind_t vm_return_kind = mp_execute_byte_code_2(code, &ip, &state[n_state - 1], &sp, exc_stack, &exc_sp); switch (vm_return_kind) { case MP_VM_RETURN_NORMAL: @@ -113,7 +105,10 @@ mp_vm_return_kind_t mp_execute_byte_code(const byte *code, const mp_obj_t *args, // MP_VM_RETURN_NORMAL, sp valid, return value in *sp // MP_VM_RETURN_YIELD, ip, sp valid, yielded value in *sp // 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_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) { // careful: be sure to declare volatile any variables read in the exception handler (written is ok, I think) const byte *ip = *ip_in_out; @@ -124,8 +119,7 @@ mp_vm_return_kind_t mp_execute_byte_code_2(const byte *code_info, const byte **i nlr_buf_t nlr; volatile machine_uint_t currently_in_except_block = 0; // 0 or 1, to detect nested exceptions - mp_exc_stack exc_stack[4]; - mp_exc_stack *volatile exc_sp = &exc_stack[0] - 1; // stack grows up, exc_sp points to top of stack + mp_exc_stack *volatile exc_sp = *exc_sp_in_out; // 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 @@ -434,7 +428,7 @@ unwind_jump: // matched against: SETUP_EXCEPT, SETUP_FINALLY, SETUP_WITH case MP_BC_POP_BLOCK: // we are exiting an exception handler, so pop the last one of the exception-stack - assert(exc_sp >= &exc_stack[0]); + assert(exc_sp >= exc_stack); currently_in_except_block = (exc_sp->val_sp & 1); // restore previous state exc_sp--; // pop back to previous exception handler break; @@ -443,7 +437,7 @@ unwind_jump: case MP_BC_POP_EXCEPT: // TODO need to work out how blocks work etc // pops block, checks it's an exception block, and restores the stack, saving the 3 exception values to local threadstate - assert(exc_sp >= &exc_stack[0]); + assert(exc_sp >= exc_stack); assert(currently_in_except_block); //sp = (mp_obj_t*)(*exc_sp--); //exc_sp--; // discard ip @@ -592,7 +586,7 @@ unwind_return: } nlr_pop(); *sp_in_out = sp; - assert(exc_sp == &exc_stack[0] - 1); + assert(exc_sp == exc_stack - 1); return MP_VM_RETURN_NORMAL; case MP_BC_RAISE_VARARGS: @@ -605,6 +599,7 @@ unwind_return: nlr_pop(); *ip_in_out = ip; *sp_in_out = sp; + *exc_sp_in_out = exc_sp; return MP_VM_RETURN_YIELD; case MP_BC_IMPORT_NAME: @@ -654,7 +649,7 @@ unwind_return: while (currently_in_except_block) { // nested exception - assert(exc_sp >= &exc_stack[0]); + assert(exc_sp >= exc_stack); // TODO make a proper message for nested exception // at the moment we are just raising the very last exception (the one that caused the nested exception) @@ -664,7 +659,7 @@ unwind_return: exc_sp--; // pop back to previous exception handler } - if (exc_sp >= &exc_stack[0]) { + if (exc_sp >= exc_stack) { // set flag to indicate that we are now handling an exception currently_in_except_block = 1; diff --git a/tests/basics/generator-exc.py b/tests/basics/generator-exc.py new file mode 100644 index 0000000000..ebcd06e974 --- /dev/null +++ b/tests/basics/generator-exc.py @@ -0,0 +1,11 @@ +# Test proper handling of exceptions within generator across yield +def gen(): + try: + yield 1 + raise ValueError + except ValueError: + print("Caught") + yield 2 + +for i in gen(): + print(i)