--- /dev/null
+.. highlightlang:: c
+
+.. _codeobjects:
+
+Code Objects
+------------
+
+.. sectionauthor:: Jeffrey Yasskin <jyasskin@gmail.com>
+
+
+.. index::
+ object: code
+
+Code objects are a low-level detail of the CPython implementation.
+Each one represents a chunk of executable code that hasn't yet been
+bound into a function.
+
+.. ctype:: PyCodeObject
+
+ The C structure of the objects used to describe code objects. The
+ fields of this type are subject to change at any time.
+
+
+.. cvar:: PyTypeObject PyCode_Type
+
+ This is an instance of :ctype:`PyTypeObject` representing the Python
+ :class:`code` type.
+
+
+.. cfunction:: int PyCode_Check(PyObject *co)
+
+ Return true if *co* is a :class:`code` object
+
+.. cfunction:: int PyCode_GetNumFree(PyObject *co)
+
+ Return the number of free variables in *co*.
+
+.. cfunction:: PyCodeObject *PyCode_New(int argcount, int nlocals, int stacksize, int flags, PyObject *code, PyObject *consts, PyObject *names, PyObject *varnames, PyObject *freevars, PyObject *cellvars, PyObject *filename, PyObject *name, int firstlineno, PyObject *lnotab)
+
+ Return a new code object. If you need a dummy code object to
+ create a frame, use :cfunc:`PyCode_NewEmpty` instead. Calling
+ :cfunc:`PyCode_New` directly can bind you to a precise Python
+ version since the definition of the bytecode changes often.
+
+
+.. cfunction:: int PyCode_NewEmpty(const char *filename, const char *funcname, int firstlineno)
+
+ Return a new empty code object with the specified filename,
+ function name, and first line number. It is illegal to
+ :keyword:`exec` or :func:`eval` the resulting code object.
cell.rst
gen.rst
datetime.rst
+ code.rst
currently executing.
+.. cfunction:: int PyFrame_GetLineNumber(PyFrameObject *frame)
+
+ Return the line number that *frame* is currently executing.
+
+
.. cfunction:: int PyEval_GetRestricted()
If there is a current frame and it is executing in restricted mode, return true,
specifies the local trace function.
``'line'``
- The interpreter is about to execute a new line of code (sometimes multiple
- line events on one line exist). The local trace function is called; *arg*
- is ``None``; the return value specifies the new local trace function.
+ The interpreter is about to execute a new line of code or re-execute the
+ condition of a loop. The local trace function is called; *arg* is
+ ``None``; the return value specifies the new local trace function. See
+ :file:`Objects/lnotab_notes.txt` for a detailed explanation of how this
+ works.
``'return'``
A function (or other code block) is about to return. The local trace
PyObject *co_filename; /* unicode (where it was loaded from) */
PyObject *co_name; /* unicode (name, for reference) */
int co_firstlineno; /* first source line number */
- PyObject *co_lnotab; /* string (encoding addr<->lineno mapping) */
+ PyObject *co_lnotab; /* string (encoding addr<->lineno mapping) See
+ Objects/lnotab_notes.txt for details. */
void *co_zombieframe; /* for optimization only (see frameobject.c) */
} PyCodeObject;
PyObject *, PyObject *, PyObject *, PyObject *,
PyObject *, PyObject *, int, PyObject *);
/* same as struct above */
+
+/* Creates a new empty code object with the specified source location. */
+PyAPI_FUNC(PyCodeObject *)
+PyCode_NewEmpty(const char *filename, const char *funcname, int firstlineno);
+
+/* Return the line number associated with the specified bytecode index
+ in this code object. If you just need the line number of a frame,
+ use PyFrame_GetLineNumber() instead. */
PyAPI_FUNC(int) PyCode_Addr2Line(PyCodeObject *, int);
/* for internal use only */
int ap_upper;
} PyAddrPair;
-/* Check whether lasti (an instruction offset) falls outside bounds
- and whether it is a line number that should be traced. Returns
- a line number if it should be traced or -1 if the line should not.
-
- If lasti is not within bounds, updates bounds.
+/* Update *bounds to describe the first and one-past-the-last instructions in the
+ same line as lasti. Return the number of that line.
*/
-
-PyAPI_FUNC(int) PyCode_CheckLineNumber(PyCodeObject* co,
- int lasti, PyAddrPair *bounds);
+PyAPI_FUNC(int) _PyCode_CheckLineNumber(PyCodeObject* co,
+ int lasti, PyAddrPair *bounds);
PyAPI_FUNC(PyObject*) PyCode_Optimize(PyObject *code, PyObject* consts,
PyObject *names, PyObject *lineno_obj);
PyThreadState *f_tstate;
int f_lasti; /* Last instruction if called */
- /* As of 2.3 f_lineno is only valid when tracing is active (i.e. when
- f_trace is set) -- at other times use PyCode_Addr2Line instead. */
+ /* Call PyFrame_GetLineNumber() instead of reading this field
+ directly. As of 2.3 f_lineno is only valid when tracing is
+ active (i.e. when f_trace is set). At other times we use
+ PyCode_Addr2Line to calculate the line from the current
+ bytecode index. */
int f_lineno; /* Current line number */
int f_iblock; /* index in f_blockstack */
PyTryBlock f_blockstack[CO_MAXBLOCKS]; /* for try and loop blocks */
PyAPI_FUNC(int) PyFrame_ClearFreeList(void);
+/* Return the line of code the frame is currently executing. */
+PyAPI_FUNC(int) PyFrame_GetLineNumber(PyFrameObject *);
+
#ifdef __cplusplus
}
#endif
"""
+import unittest
+import _testcapi
+
def consts(t):
"""Yield a doctest-safe sequence of object reprs."""
for elt in t:
print("%s: %s" % (attr, getattr(co, "co_" + attr)))
print("consts:", tuple(consts(co.co_consts)))
+
+class CodeTest(unittest.TestCase):
+
+ def test_newempty(self):
+ co = _testcapi.code_newempty("filename", "funcname", 15)
+ self.assertEquals(co.co_filename, "filename")
+ self.assertEquals(co.co_name, "funcname")
+ self.assertEquals(co.co_firstlineno, 15)
+
+
def test_main(verbose=None):
- from test.support import run_doctest
+ from test.support import run_doctest, run_unittest
from test import test_code
run_doctest(test_code, verbose)
+ run_unittest(CodeTest)
if __name__ == '__main__':
- The code flags for old __future__ features are now available again.
+- Issue #5954: Add a PyFrame_GetLineNumber() function to replace most uses of
+ PyCode_Addr2Line().
+
+- Issue #5959: Add a PyCode_NewEmpty() function to create a new empty code
+ object at a specified file, function, and line number.
+
+- Issue #1419652: Change the first argument to PyImport_AppendInittab() to
+ ``const char *`` as the string is stored beyond the call.
+
Library
-------
/* after code that pyrex generates */
void _ctypes_add_traceback(char *funcname, char *filename, int lineno)
{
- PyObject *py_srcfile = 0;
- PyObject *py_funcname = 0;
PyObject *py_globals = 0;
- PyObject *empty_tuple = 0;
- PyObject *empty_string = 0;
PyCodeObject *py_code = 0;
PyFrameObject *py_frame = 0;
- py_srcfile = PyUnicode_DecodeFSDefault(filename);
- if (!py_srcfile) goto bad;
- py_funcname = PyUnicode_FromString(funcname);
- if (!py_funcname) goto bad;
py_globals = PyDict_New();
if (!py_globals) goto bad;
- empty_tuple = PyTuple_New(0);
- if (!empty_tuple) goto bad;
- empty_string = PyBytes_FromString("");
- if (!empty_string) goto bad;
- py_code = PyCode_New(
- 0, /*int argcount,*/
- 0, /*int kwonlyargcount,*/
- 0, /*int nlocals,*/
- 0, /*int stacksize,*/
- 0, /*int flags,*/
- empty_string, /*PyObject *code,*/
- empty_tuple, /*PyObject *consts,*/
- empty_tuple, /*PyObject *names,*/
- empty_tuple, /*PyObject *varnames,*/
- empty_tuple, /*PyObject *freevars,*/
- empty_tuple, /*PyObject *cellvars,*/
- py_srcfile, /*PyObject *filename,*/
- py_funcname, /*PyObject *name,*/
- lineno, /*int firstlineno,*/
- empty_string /*PyObject *lnotab*/
- );
+ py_code = PyCode_NewEmpty(filename, funcname, lineno);
if (!py_code) goto bad;
py_frame = PyFrame_New(
PyThreadState_Get(), /*PyThreadState *tstate,*/
PyTraceBack_Here(py_frame);
bad:
Py_XDECREF(py_globals);
- Py_XDECREF(py_srcfile);
- Py_XDECREF(py_funcname);
- Py_XDECREF(empty_tuple);
- Py_XDECREF(empty_string);
Py_XDECREF(py_code);
Py_XDECREF(py_frame);
}
Py_RETURN_NONE;
}
+/* To test that the result of PyCode_NewEmpty has the right members. */
+static PyObject *
+code_newempty(PyObject *self, PyObject *args)
+{
+ const char *filename;
+ const char *funcname;
+ int firstlineno;
+
+ if (!PyArg_ParseTuple(args, "ssi:code_newempty",
+ &filename, &funcname, &firstlineno))
+ return NULL;
+
+ return (PyObject *)PyCode_NewEmpty(filename, funcname, firstlineno);
+}
+
static PyMethodDef TestMethods[] = {
{"raise_exception", raise_exception, METH_VARARGS},
{"raise_memoryerror", (PyCFunction)raise_memoryerror, METH_NOARGS},
{"traceback_print", traceback_print, METH_VARARGS},
{"exception_print", exception_print, METH_VARARGS},
{"argparsing", argparsing, METH_VARARGS},
+ {"code_newempty", code_newempty, METH_VARARGS},
{NULL, NULL} /* sentinel */
};
static PyCodeObject*
getcode(enum HandlerTypes slot, char* func_name, int lineno)
{
- PyObject *code = NULL;
- PyObject *name = NULL;
- PyObject *nulltuple = NULL;
- PyObject *filename = NULL;
-
if (handler_info[slot].tb_code == NULL) {
- code = PyBytes_FromString("");
- if (code == NULL)
- goto failed;
- name = PyUnicode_FromString(func_name);
- if (name == NULL)
- goto failed;
- nulltuple = PyTuple_New(0);
- if (nulltuple == NULL)
- goto failed;
- filename = PyUnicode_DecodeFSDefault(__FILE__);
handler_info[slot].tb_code =
- PyCode_New(0, /* argcount */
- 0, /* kwonlyargcount */
- 0, /* nlocals */
- 0, /* stacksize */
- 0, /* flags */
- code, /* code */
- nulltuple, /* consts */
- nulltuple, /* names */
- nulltuple, /* varnames */
-#if PYTHON_API_VERSION >= 1010
- nulltuple, /* freevars */
- nulltuple, /* cellvars */
-#endif
- filename, /* filename */
- name, /* name */
- lineno, /* firstlineno */
- code /* lnotab */
- );
- if (handler_info[slot].tb_code == NULL)
- goto failed;
- Py_DECREF(code);
- Py_DECREF(nulltuple);
- Py_DECREF(filename);
- Py_DECREF(name);
+ PyCode_NewEmpty(__FILE__, func_name, lineno);
}
return handler_info[slot].tb_code;
- failed:
- Py_XDECREF(code);
- Py_XDECREF(name);
- return NULL;
}
#ifdef FIX_TRACE
Py_ssize_t i;
/* Check argument types */
- if (argcount < 0 || nlocals < 0 ||
+ if (argcount < 0 || kwonlyargcount < 0 || nlocals < 0 ||
code == NULL ||
consts == NULL || !PyTuple_Check(consts) ||
names == NULL || !PyTuple_Check(names) ||
return co;
}
+PyCodeObject *
+PyCode_NewEmpty(const char *filename, const char *funcname, int firstlineno)
+{
+ static PyObject *emptystring = NULL;
+ static PyObject *nulltuple = NULL;
+ PyObject *filename_ob = NULL;
+ PyObject *funcname_ob = NULL;
+ PyCodeObject *result = NULL;
+ if (emptystring == NULL) {
+ emptystring = PyBytes_FromString("");
+ if (emptystring == NULL)
+ goto failed;
+ }
+ if (nulltuple == NULL) {
+ nulltuple = PyTuple_New(0);
+ if (nulltuple == NULL)
+ goto failed;
+ }
+ funcname_ob = PyUnicode_FromString(funcname);
+ if (funcname_ob == NULL)
+ goto failed;
+ filename_ob = PyUnicode_DecodeFSDefault(filename);
+ if (filename_ob == NULL)
+ goto failed;
+
+ result = PyCode_New(0, /* argcount */
+ 0, /* kwonlyargcount */
+ 0, /* nlocals */
+ 0, /* stacksize */
+ 0, /* flags */
+ emptystring, /* code */
+ nulltuple, /* consts */
+ nulltuple, /* names */
+ nulltuple, /* varnames */
+ nulltuple, /* freevars */
+ nulltuple, /* cellvars */
+ filename_ob, /* filename */
+ funcname_ob, /* name */
+ firstlineno, /* firstlineno */
+ emptystring /* lnotab */
+ );
+
+failed:
+ Py_XDECREF(funcname_ob);
+ Py_XDECREF(filename_ob);
+ return result;
+}
#define OFF(x) offsetof(PyCodeObject, x)
code_new, /* tp_new */
};
-/* All about c_lnotab.
-
-c_lnotab is an array of unsigned bytes disguised as a Python string. In -O
-mode, SET_LINENO opcodes aren't generated, and bytecode offsets are mapped
-to source code line #s (when needed for tracebacks) via c_lnotab instead.
-The array is conceptually a list of
- (bytecode offset increment, line number increment)
-pairs. The details are important and delicate, best illustrated by example:
-
- byte code offset source code line number
- 0 1
- 6 2
- 50 7
- 350 307
- 361 308
-
-The first trick is that these numbers aren't stored, only the increments
-from one row to the next (this doesn't really work, but it's a start):
-
- 0, 1, 6, 1, 44, 5, 300, 300, 11, 1
-
-The second trick is that an unsigned byte can't hold negative values, or
-values larger than 255, so (a) there's a deep assumption that byte code
-offsets and their corresponding line #s both increase monotonically, and (b)
-if at least one column jumps by more than 255 from one row to the next, more
-than one pair is written to the table. In case #b, there's no way to know
-from looking at the table later how many were written. That's the delicate
-part. A user of c_lnotab desiring to find the source line number
-corresponding to a bytecode address A should do something like this
-
- lineno = addr = 0
- for addr_incr, line_incr in c_lnotab:
- addr += addr_incr
- if addr > A:
- return lineno
- lineno += line_incr
-
-In order for this to work, when the addr field increments by more than 255,
-the line # increment in each pair generated must be 0 until the remaining addr
-increment is < 256. So, in the example above, com_set_lineno should not (as
-was actually done until 2.2) expand 300, 300 to 255, 255, 45, 45, but to
-255, 0, 45, 255, 0, 45.
+/* Use co_lnotab to compute the line number from a bytecode index, addrq. See
+ lnotab_notes.txt for the details of the lnotab representation.
*/
int
return line;
}
-/*
- Check whether the current instruction is at the start of a line.
-
- */
-
- /* The theory of SET_LINENO-less tracing.
-
- In a nutshell, we use the co_lnotab field of the code object
- to tell when execution has moved onto a different line.
-
- As mentioned above, the basic idea is so set things up so
- that
-
- *instr_lb <= frame->f_lasti < *instr_ub
-
- is true so long as execution does not change lines.
-
- This is all fairly simple. Digging the information out of
- co_lnotab takes some work, but is conceptually clear.
-
- Somewhat harder to explain is why we don't *always* call the
- line trace function when the above test fails.
-
- Consider this code:
-
- 1: def f(a):
- 2: if a:
- 3: print 1
- 4: else:
- 5: print 2
-
- which compiles to this:
-
- 2 0 LOAD_FAST 0 (a)
- 3 JUMP_IF_FALSE 9 (to 15)
- 6 POP_TOP
-
- 3 7 LOAD_CONST 1 (1)
- 10 PRINT_ITEM
- 11 PRINT_NEWLINE
- 12 JUMP_FORWARD 6 (to 21)
- >> 15 POP_TOP
-
- 5 16 LOAD_CONST 2 (2)
- 19 PRINT_ITEM
- 20 PRINT_NEWLINE
- >> 21 LOAD_CONST 0 (None)
- 24 RETURN_VALUE
-
- If 'a' is false, execution will jump to instruction at offset
- 15 and the co_lnotab will claim that execution has moved to
- line 3. This is at best misleading. In this case we could
- associate the POP_TOP with line 4, but that doesn't make
- sense in all cases (I think).
-
- What we do is only call the line trace function if the co_lnotab
- indicates we have jumped to the *start* of a line, i.e. if the
- current instruction offset matches the offset given for the
- start of a line by the co_lnotab.
-
- This also takes care of the situation where 'a' is true.
- Execution will jump from instruction offset 12 to offset 21.
- Then the co_lnotab would imply that execution has moved to line
- 5, which is again misleading.
-
- Why do we set f_lineno when tracing? Well, consider the code
- above when 'a' is true. If stepping through this with 'n' in
- pdb, you would stop at line 1 with a "call" type event, then
- line events on lines 2 and 3, then a "return" type event -- but
- you would be shown line 5 during this event. This is a change
- from the behaviour in 2.2 and before, and I've found it
- confusing in practice. By setting and using f_lineno when
- tracing, one can report a line number different from that
- suggested by f_lasti on this one occasion where it's desirable.
- */
-
-
-int
-PyCode_CheckLineNumber(PyCodeObject* co, int lasti, PyAddrPair *bounds)
+/* Update *bounds to describe the first and one-past-the-last instructions in
+ the same line as lasti. Return the number of that line. */
+int
+_PyCode_CheckLineNumber(PyCodeObject* co, int lasti, PyAddrPair *bounds)
{
int size, addr, line;
unsigned char* p;
instr_lb -- if we stored the matching value of p
somwhere we could skip the first while loop. */
- /* see comments in compile.c for the description of
+ /* See lnotab_notes.txt for the description of
co_lnotab. A point to remember: increments to p
- should come in pairs -- although we don't care about
- the line increments here, treating them as byte
- increments gets confusing, to say the least. */
+ come in (addr, line) pairs. */
bounds->ap_lower = 0;
while (size > 0) {
--size;
}
- /* If lasti and addr don't match exactly, we don't want to
- change the lineno slot on the frame or execute a trace
- function. Return -1 instead.
- */
- if (addr != lasti)
- line = -1;
-
if (size > 0) {
while (--size >= 0) {
addr += *p++;
return f->f_locals;
}
-static PyObject *
-frame_getlineno(PyFrameObject *f, void *closure)
+int
+PyFrame_GetLineNumber(PyFrameObject *f)
{
- int lineno;
-
if (f->f_trace)
- lineno = f->f_lineno;
+ return f->f_lineno;
else
- lineno = PyCode_Addr2Line(f->f_code, f->f_lasti);
+ return PyCode_Addr2Line(f->f_code, f->f_lasti);
+}
- return PyLong_FromLong(lineno);
+static PyObject *
+frame_getlineno(PyFrameObject *f, void *closure)
+{
+ return PyLong_FromLong(PyFrame_GetLineNumber(f));
}
/* Setter for f_lineno - you can set f_lineno from within a trace function in
static int
frame_settrace(PyFrameObject *f, PyObject* v, void *closure)
{
- /* We rely on f_lineno being accurate when f_trace is set. */
+ PyObject* old_value;
- PyObject* old_value = f->f_trace;
+ /* We rely on f_lineno being accurate when f_trace is set. */
+ f->f_lineno = PyFrame_GetLineNumber(f);
+ old_value = f->f_trace;
Py_XINCREF(v);
f->f_trace = v;
-
- if (v != NULL)
- f->f_lineno = PyCode_Addr2Line(f->f_code, f->f_lasti);
-
Py_XDECREF(old_value);
return 0;
--- /dev/null
+All about co_lnotab, the line number table.
+
+Code objects store a field named co_lnotab. This is an array of unsigned bytes
+disguised as a Python string. It is used to map bytecode offsets to source code
+line #s for tracebacks and to identify line number boundaries for line tracing.
+
+The array is conceptually a compressed list of
+ (bytecode offset increment, line number increment)
+pairs. The details are important and delicate, best illustrated by example:
+
+ byte code offset source code line number
+ 0 1
+ 6 2
+ 50 7
+ 350 307
+ 361 308
+
+Instead of storing these numbers literally, we compress the list by storing only
+the increments from one row to the next. Conceptually, the stored list might
+look like:
+
+ 0, 1, 6, 1, 44, 5, 300, 300, 11, 1
+
+The above doesn't really work, but it's a start. Note that an unsigned byte
+can't hold negative values, or values larger than 255, and the above example
+contains two such values. So we make two tweaks:
+
+ (a) there's a deep assumption that byte code offsets and their corresponding
+ line #s both increase monotonically, and
+ (b) if at least one column jumps by more than 255 from one row to the next,
+ more than one pair is written to the table. In case #b, there's no way to know
+ from looking at the table later how many were written. That's the delicate
+ part. A user of co_lnotab desiring to find the source line number
+ corresponding to a bytecode address A should do something like this
+
+ lineno = addr = 0
+ for addr_incr, line_incr in co_lnotab:
+ addr += addr_incr
+ if addr > A:
+ return lineno
+ lineno += line_incr
+
+(In C, this is implemented by PyCode_Addr2Line().) In order for this to work,
+when the addr field increments by more than 255, the line # increment in each
+pair generated must be 0 until the remaining addr increment is < 256. So, in
+the example above, assemble_lnotab in compile.c should not (as was actually done
+until 2.2) expand 300, 300 to
+ 255, 255, 45, 45,
+but to
+ 255, 0, 45, 255, 0, 45.
+
+The above is sufficient to reconstruct line numbers for tracebacks, but not for
+line tracing. Tracing is handled by PyCode_CheckLineNumber() in codeobject.c
+and maybe_call_line_trace() in ceval.c.
+
+*** Tracing ***
+
+To a first approximation, we want to call the tracing function when the line
+number of the current instruction changes. Re-computing the current line for
+every instruction is a little slow, though, so each time we compute the line
+number we save the bytecode indices where it's valid:
+
+ *instr_lb <= frame->f_lasti < *instr_ub
+
+is true so long as execution does not change lines. That is, *instr_lb holds
+the first bytecode index of the current line, and *instr_ub holds the first
+bytecode index of the next line. As long as the above expression is true,
+maybe_call_line_trace() does not need to call PyCode_CheckLineNumber(). Note
+that the same line may appear multiple times in the lnotab, either because the
+bytecode jumped more than 255 indices between line number changes or because
+the compiler inserted the same line twice. Even in that case, *instr_ub holds
+the first index of the next line.
+
+However, we don't *always* want to call the line trace function when the above
+test fails.
+
+Consider this code:
+
+1: def f(a):
+2: while a:
+3: print 1,
+4: break
+5: else:
+6: print 2,
+
+which compiles to this:
+
+ 2 0 SETUP_LOOP 19 (to 22)
+ >> 3 LOAD_FAST 0 (a)
+ 6 POP_JUMP_IF_FALSE 17
+
+ 3 9 LOAD_CONST 1 (1)
+ 12 PRINT_ITEM
+
+ 4 13 BREAK_LOOP
+ 14 JUMP_ABSOLUTE 3
+ >> 17 POP_BLOCK
+
+ 6 18 LOAD_CONST 2 (2)
+ 21 PRINT_ITEM
+ >> 22 LOAD_CONST 0 (None)
+ 25 RETURN_VALUE
+
+If 'a' is false, execution will jump to the POP_BLOCK instruction at offset 17
+and the co_lnotab will claim that execution has moved to line 4, which is wrong.
+In this case, we could instead associate the POP_BLOCK with line 5, but that
+would break jumps around loops without else clauses.
+
+We fix this by only calling the line trace function for a forward jump if the
+co_lnotab indicates we have jumped to the *start* of a line, i.e. if the current
+instruction offset matches the offset given for the start of a line by the
+co_lnotab. For backward jumps, however, we always call the line trace function,
+which lets a debugger stop on every evaluation of a loop guard (which usually
+won't be the first opcode in a line).
+
+Why do we set f_lineno when tracing, and only just before calling the trace
+function? Well, consider the code above when 'a' is true. If stepping through
+this with 'n' in pdb, you would stop at line 1 with a "call" type event, then
+line events on lines 2, 3, and 4, then a "return" type event -- but because the
+code for the return actually falls in the range of the "line 6" opcodes, you
+would be shown line 6 during this event. This is a change from the behaviour in
+2.2 and before, and I've found it confusing in practice. By setting and using
+f_lineno when tracing, one can report a line number different from that
+suggested by f_lasti on this one occasion where it's desirable.
}
else {
globals = f->f_globals;
- *lineno = PyCode_Addr2Line(f->f_code, f->f_lasti);
+ *lineno = PyFrame_GetLineNumber(f);
}
*module = NULL;
default:
fprintf(stderr,
"XXX lineno: %d, opcode: %d\n",
- PyCode_Addr2Line(f->f_code, f->f_lasti),
+ PyFrame_GetLineNumber(f),
opcode);
PyErr_SetString(PyExc_SystemError, "unknown opcode");
why = WHY_EXCEPTION;
return result;
}
+/* See Objects/lnotab_notes.txt for a description of how tracing works. */
static int
maybe_call_line_trace(Py_tracefunc func, PyObject *obj,
PyFrameObject *frame, int *instr_lb, int *instr_ub,
int *instr_prev)
{
int result = 0;
+ int line = frame->f_lineno;
/* If the last instruction executed isn't in the current
- instruction window, reset the window. If the last
- instruction happens to fall at the start of a line or if it
- represents a jump backwards, call the trace function.
+ instruction window, reset the window.
*/
- if ((frame->f_lasti < *instr_lb || frame->f_lasti >= *instr_ub)) {
- int line;
+ if (frame->f_lasti < *instr_lb || frame->f_lasti >= *instr_ub) {
PyAddrPair bounds;
-
- line = PyCode_CheckLineNumber(frame->f_code, frame->f_lasti,
- &bounds);
- if (line >= 0) {
- frame->f_lineno = line;
- result = call_trace(func, obj, frame,
- PyTrace_LINE, Py_None);
- }
+ line = _PyCode_CheckLineNumber(frame->f_code, frame->f_lasti,
+ &bounds);
*instr_lb = bounds.ap_lower;
*instr_ub = bounds.ap_upper;
}
- else if (frame->f_lasti <= *instr_prev) {
+ /* If the last instruction falls at the start of a line or if
+ it represents a jump backwards, update the frame's line
+ number and call the trace function. */
+ if (frame->f_lasti == *instr_lb || frame->f_lasti < *instr_prev) {
+ frame->f_lineno = line;
result = call_trace(func, obj, frame, PyTrace_LINE, Py_None);
}
*instr_prev = frame->f_lasti;
VISIT(c, expr, s->v.For.iter);
ADDOP(c, GET_ITER);
compiler_use_next_block(c, start);
- /* for expressions must be traced on each iteration,
- so we need to set an extra line number. */
- c->u->u_lineno_set = 0;
ADDOP_JREL(c, FOR_ITER, cleanup);
VISIT(c, expr, s->v.For.target);
VISIT_SEQ(c, stmt, s->v.For.body);
if (!compiler_push_fblock(c, LOOP, loop))
return 0;
if (constant == -1) {
- /* while expressions must be traced on each iteration,
- so we need to set an extra line number. */
- c->u->u_lineno_set = 0;
VISIT(c, expr, s->v.While.test);
ADDOP_JABS(c, POP_JUMP_IF_FALSE, anchor);
}
return size;
}
-/* All about a_lnotab.
-
-c_lnotab is an array of unsigned bytes disguised as a Python string.
-It is used to map bytecode offsets to source code line #s (when needed
-for tracebacks).
-
-The array is conceptually a list of
- (bytecode offset increment, line number increment)
-pairs. The details are important and delicate, best illustrated by example:
-
- byte code offset source code line number
- 0 1
- 6 2
- 50 7
- 350 307
- 361 308
-
-The first trick is that these numbers aren't stored, only the increments
-from one row to the next (this doesn't really work, but it's a start):
-
- 0, 1, 6, 1, 44, 5, 300, 300, 11, 1
-
-The second trick is that an unsigned byte can't hold negative values, or
-values larger than 255, so (a) there's a deep assumption that byte code
-offsets and their corresponding line #s both increase monotonically, and (b)
-if at least one column jumps by more than 255 from one row to the next, more
-than one pair is written to the table. In case #b, there's no way to know
-from looking at the table later how many were written. That's the delicate
-part. A user of c_lnotab desiring to find the source line number
-corresponding to a bytecode address A should do something like this
-
- lineno = addr = 0
- for addr_incr, line_incr in c_lnotab:
- addr += addr_incr
- if addr > A:
- return lineno
- lineno += line_incr
-
-In order for this to work, when the addr field increments by more than 255,
-the line # increment in each pair generated must be 0 until the remaining addr
-increment is < 256. So, in the example above, assemble_lnotab (it used
-to be called com_set_lineno) should not (as was actually done until 2.2)
-expand 300, 300 to 255, 255, 45, 45,
- but to 255, 0, 45, 255, 0, 45.
-*/
+/* Appends a pair to the end of the line number table, a_lnotab, representing
+ the instruction's bytecode offset and line number. See
+ Objects/lnotab_notes.txt for the description of the line number table. */
static int
assemble_lnotab(struct assembler *a, struct instr *i)
Py_XINCREF(frame);
tb->tb_frame = frame;
tb->tb_lasti = frame->f_lasti;
- tb->tb_lineno = PyCode_Addr2Line(frame->f_code,
- frame->f_lasti);
+ tb->tb_lineno = PyFrame_GetLineNumber(frame);
PyObject_GC_Track(tb);
}
return tb;
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