Remove special-casing from FORMAT_VALUE opcode

Right now there's a special case in handling this opcode:

Lines 3060 to 3073 in 5ffdaf7

    
8000
     
                       /* If value is a unicode object, and there's no fmt_spec, 
        
                          then we know the result of format(value) is value 
        
                          itself. In that case, skip calling format(). I plan to 
        
                          move this optimization in to PyObject_Format() 
        
                          itself. */ 
        
                       if (PyUnicode_CheckExact(value) && fmt_spec == NULL) { 
        
                           /* Do nothing, just transfer ownership to result. */ 
        
                           result = value; 
        
                       } else { 
        
                           /* Actually call format(). */ 
        
                           result = PyObject_Format(value, fmt_spec); 
        
                           Py_DECREF(value); 
        
                           Py_XDECREF(fmt_spec); 
        
                           ERROR_IF(result == NULL, error);

It comes from older version of ceval.c:

cpython/Python/ceval.c

Lines 4379 to 4395 in 2810787

    
                       /* If value is a unicode object, and there's no fmt_spec, 
        
                          then we know the result of format(value) is value 
        
                          itself. In that case, skip calling format(). I plan to 
        
                          move this optimization in to PyObject_Format() 
        
                          itself. */ 
        
                       if (PyUnicode_CheckExact(value) && fmt_spec == NULL) { 
        
                           /* Do nothing, just transfer ownership to result. */ 
        
                           result = value; 
        
                       } else { 
        
                           /* Actually call format(). */ 
        
                           result = PyObject_Format(value, fmt_spec); 
        
                           Py_DECREF(value); 
        
                           Py_XDECREF(fmt_spec); 
        
                           if (result == NULL) { 
        
                               goto error; 
        
                           } 
        
                       }

But, I think that the needed optimizaion is there:

cpython/Objects/abstract.c

Lines 774 to 777 in 5ffdaf7

    
           if (format_spec == NULL || PyUnicode_GET_LENGTH(format_spec) == 0) { 
        
               if (PyUnicode_CheckExact(obj)) { 
        
                   return Py_NewRef(obj); 
        
               }

So, I think this can be safely removed.
I will send a PR.

Linked PRs

gh-102598: Remove obsolete optimization from FORMAT_VALUE opcode #102599

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	/* If value is a unicode object, and there's no fmt_spec,
	then we know the result of format(value) is value
	itself. In that case, skip calling format(). I plan to
	move this optimization in to PyObject_Format()
	itself. */
	if (PyUnicode_CheckExact(value) && fmt_spec == NULL) {
	/* Do nothing, just transfer ownership to result. */
	result = value;
	} else {
	/* Actually call format(). */
	result = PyObject_Format(value, fmt_spec);
	Py_DECREF(value);
	Py_XDECREF(fmt_spec);
	ERROR_IF(result == NULL, error);

	if (format_spec == NULL \|\| PyUnicode_GET_LENGTH(format_spec) == 0) {
	if (PyUnicode_CheckExact(obj)) {
	return Py_NewRef(obj);
	}

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