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methanemethane
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Issue #26110: Add document for LOAD_METHOD and CALL_METHOD opcode.
Changed stack layout bit for "easy to explain."
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Lines changed: 61 additions & 40 deletions

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‎Doc/library/dis.rst‎

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@@ -957,6 +957,28 @@ All of the following opcodes use their arguments.
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value.
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.. opcode:: LOAD_METHOD (namei)
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Loads a method named ``co_names[namei]`` from TOS object. TOS is popped and
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method and TOS are pushed when interpreter can call unbound method directly.
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TOS will be uesd as the first argument (``self``) by :opcode:`CALL_METHOD`.
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Otherwise, ``NULL`` and method is pushed (method is bound method or
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something else).
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.. versionadded:: 3.7
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.. opcode:: CALL_METHOD (argc)
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Calls a method. *argc* is number of positional arguments.
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Keyword arguments are not supported. This opcode is designed to be used
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with :opcode:`LOAD_METHOD`. Positional arguments are on top of the stack.
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Below them, two items described in :opcode:`LOAD_METHOD` on the stack.
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All of them are popped and return value is pushed.
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.. versionadded:: 3.7
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.. opcode:: MAKE_FUNCTION (argc)
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Pushes a new function object on the stack. From bottom to top, the consumed

‎Doc/whatsnew/3.7.rst‎

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@@ -170,3 +170,10 @@ Changes in the Python API
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Assigning to them was deprecated in Python 3.5.
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Use the :meth:`~http.cookies.Morsel.set` method for setting them.
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(Contributed by Serhiy Storchaka in :issue:`29192`.)
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CPython bytecode changes
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------------------------
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* Added two new opcodes: :opcode:`LOAD_METHOD`` and :opcode:`CALL_METHOD`.
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(Contributed by Yury Selivanov and INADA Naoki in :issue:`26110`.)

‎Python/ceval.c‎

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Original file line numberDiff line numberDiff line change
@@ -3236,81 +3236,73 @@ _PyEval_EvalFrameDefault(PyFrameObject *f, int throwflag)
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int meth_found = _PyObject_GetMethod(obj, name, &meth);
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SET_TOP(meth); /* Replace `obj` on top; OK if NULL. */
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if (meth == NULL) {
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/* Most likely attribute wasn't found. */
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Py_DECREF(obj);
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goto error;
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}
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if (meth_found) {
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/* The method object is now on top of the stack.
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Push `obj` back to the stack, so that the stack
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layout would be:
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method | obj | arg1 | ... | argN
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*/
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PUSH(obj);
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/* We can bypass temporary bound method object.
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meth is unbound method and obj is self.
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meth | self | arg1 | ... | argN
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*/
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SET_TOP(meth);
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PUSH(obj); // self
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}
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else {
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/* Not a method (but a regular attr, or something
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was returned by a descriptor protocol). Push
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NULL to the top of the stack, to signal
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/* meth is not an unbound method (but a regular attr, or
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something was returned by a descriptor protocol). Set
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the second element of the stack to NULL, to signal
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CALL_METHOD that it's not a method call.
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NULL | meth | arg1 | ... | argN
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*/
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SET_TOP(NULL);
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Py_DECREF(obj);
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PUSH(NULL);
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PUSH(meth);
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}
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DISPATCH();
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}
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TARGET(CALL_METHOD) {
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/* Designed to work in tamdem with LOAD_METHOD. */
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PyObject **sp, *res, *obj;
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PyObject **sp, *res, *meth;
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sp = stack_pointer;
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obj = PEEK(oparg + 1);
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if (obj == NULL) {
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/* `obj` is NULL when LOAD_METHOD thinks that it's not
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a method call. Swap the NULL and callable.
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meth = PEEK(oparg + 2);
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if (meth == NULL) {
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/* `meth` is NULL when LOAD_METHOD thinks that it's not
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a method call.
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Stack layout:
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3280-
... | callable | NULL | arg1 | ... | argN
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^- TOP()
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^- (-oparg)
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^- (-oparg-1)
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^- (-oparg-2)
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after the next line it will be:
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... | callable | callable | arg1 | ... | argN
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^- TOP()
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^- (-oparg)
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^- (-oparg-1)
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^- (-oparg-2)
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... | NULL | callable | arg1 | ... | argN
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^- TOP()
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^- (-oparg)
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^- (-oparg-1)
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^- (-oparg-2)
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Right side `callable` will be POPed by call_funtion.
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Left side `callable` will be POPed manually later
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(one of "callbale" refs on the stack is borrowed.)
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`callable` will be POPed by call_funtion.
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NULL will will be POPed manually later.
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*/
3298-
SET_VALUE(oparg + 1, PEEK(oparg + 2));
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res = call_function(&sp, oparg, NULL);
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stack_pointer = sp;
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(void)POP(); /* POP the left side callable. */
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(void)POP(); /* POP the NULL. */
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}
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else {
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/* This is a method call. Stack layout:
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3306-
... | method | obj | arg1 | ... | argN
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... | method | self | arg1 | ... | argN
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^- TOP()
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^- (-oparg)
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^- (-oparg-1)
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^- (-oparg-1)
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^- (-oparg-2)
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3311-
`obj` and `method` will be POPed by call_function.
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`self` and `method` will be POPed by call_function.
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We'll be passing `oparg + 1` to call_function, to
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make it accept the `obj` as a first argument.
3305+
make it accept the `self` as a first argument.
33143306
*/
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res = call_function(&sp, oparg + 1, NULL);
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stack_pointer = sp;

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