/* Compile an expression node to intermediate code */

/* XXX TO DO:

XXX add __doc__ attribute == co_doc to code object attributes?

XXX (it's currently the first item of the co_const tuple)

XXX Generate simple jump for break/return outside 'try...finally'

XXX Allow 'continue' inside finally clause of try-finally

XXX New opcode for loading the initial index for a for loop

XXX other JAR tricks?

*/

#include "Python.h"

#include "node.h"

#include "token.h"

#include "graminit.h"

#include "compile.h"

#include "symtable.h"

#include "opcode.h"

#include "structmember.h"

#include <ctype.h>

/* Three symbols from graminit.h are also defined in Python.h, with

Py_ prefixes to their names. Python.h can't include graminit.h

(which defines too many confusing symbols), but we can check here

that they haven't changed (which is very unlikely, but possible). */

#if Py_single_input != single_input

#error "single_input has changed -- update Py_single_input in Python.h"

#endif

#if Py_file_input != file_input

#error "file_input has changed -- update Py_file_input in Python.h"

#endif

#if Py_eval_input != eval_input

#error "eval_input has changed -- update Py_eval_input in Python.h"

#endif

int Py_OptimizeFlag = 0;

#define OP_DELETE 0

#define OP_ASSIGN 1

#define OP_APPLY 2

#define VAR_LOAD 0

#define VAR_STORE 1

#define VAR_DELETE 2

#define DEL_CLOSURE_ERROR \

"can not delete variable '%.400s' referenced in nested scope"

#define DUPLICATE_ARGUMENT \

"duplicate argument '%s' in function definition"

#define GLOBAL_AFTER_ASSIGN \

"name '%.400s' is assigned to before global declaration"

#define GLOBAL_AFTER_USE \

"name '%.400s' is used prior to global declaration"

#define PARAM_GLOBAL \

"name '%.400s' is a function parameter and declared global"

#define LATE_FUTURE \

"from __future__ imports must occur at the beginning of the file"

#define ASSIGN_DEBUG \

"can not assign to __debug__"

#define MANGLE_LEN 256

#define OFF(x) offsetof(PyCodeObject, x)

static PyMemberDef code_memberlist[] = {

{"co_argcount", T_INT, OFF(co_argcount), READONLY},

{"co_nlocals", T_INT, OFF(co_nlocals), READONLY},

{"co_stacksize",T_INT, OFF(co_stacksize), READONLY},

{"co_flags", T_INT, OFF(co_flags), READONLY},

{"co_code", T_OBJECT, OFF(co_code), READONLY},

{"co_consts", T_OBJECT, OFF(co_consts), READONLY},

{"co_names", T_OBJECT, OFF(co_names), READONLY},

{"co_varnames", T_OBJECT, OFF(co_varnames), READONLY},

{"co_freevars", T_OBJECT, OFF(co_freevars), READONLY},

{"co_cellvars", T_OBJECT, OFF(co_cellvars), READONLY},

{"co_filename", T_OBJECT, OFF(co_filename), READONLY},

{"co_name", T_OBJECT, OFF(co_name), READONLY},

{"co_firstlineno", T_INT, OFF(co_firstlineno), READONLY},

{"co_lnotab", T_OBJECT, OFF(co_lnotab), READONLY},

{NULL} /* Sentinel */

};

/* Helper for code_new: return a shallow copy of a tuple that is

guaranteed to contain exact strings, by converting string subclasses

to exact strings and complaining if a non-string is found. */

static PyObject*

validate_and_copy_tuple(PyObject *tup)

{

PyObject *newtuple;

PyObject *item;

int i, len;

len = PyTuple_GET_SIZE(tup);

newtuple = PyTuple_New(len);

if (newtuple == NULL)

return NULL;

for (i = 0; i < len; i++) {

item = PyTuple_GET_ITEM(tup, i);

if (PyString_CheckExact(item)) {

Py_INCREF(item);

}

else if (!PyString_Check(item)) {

PyErr_Format(

PyExc_TypeError,

"name tuples must contain only "

"strings, not '%.500s'",

item->ob_type->tp_name);

Py_DECREF(newtuple);

return NULL;

}

else {

item = PyString_FromStringAndSize(

PyString_AS_STRING(item),

PyString_GET_SIZE(item));

if (item == NULL) {

Py_DECREF(newtuple);

return NULL;

}

}

PyTuple_SET_ITEM(newtuple, i, item);

}

return newtuple;

}

PyDoc_STRVAR(code_doc,

"code(argcount, nlocals, stacksize, flags, codestring, constants, names,\n\

varnames, filename, name, firstlineno, lnotab[, freevars[, cellvars]])\n\

\n\

Create a code object. Not for the faint of heart.");

static PyObject *

code_new(PyTypeObject *type, PyObject *args, PyObject *kw)

{

int argcount;

int nlocals;

int stacksize;

int flags;

PyObject *co = NULL;

PyObject *code;

PyObject *consts;

PyObject *names, *ournames = NULL;

PyObject *varnames, *ourvarnames = NULL;

PyObject *freevars = NULL, *ourfreevars = NULL;

PyObject *cellvars = NULL, *ourcellvars = NULL;

PyObject *filename;

PyObject *name;

int firstlineno;

PyObject *lnotab;

if (!PyArg_ParseTuple(args, "iiiiSO!O!O!SSiS|O!O!:code",

&argcount, &nlocals, &stacksize, &flags,

&code,

&PyTuple_Type, &consts,

&PyTuple_Type, &names,

&PyTuple_Type, &varnames,

&filename, &name,

&firstlineno, &lnotab,

&PyTuple_Type, &freevars,

&PyTuple_Type, &cellvars))

return NULL;

if (argcount < 0) {

PyErr_SetString(

PyExc_ValueError,

"code: argcount must not be negative");

goto cleanup;

}

if (nlocals < 0) {

PyErr_SetString(

PyExc_ValueError,

"code: nlocals must not be negative");

goto cleanup;

}

ournames = validate_and_copy_tuple(names);

if (ournames == NULL)

goto cleanup;

ourvarnames = validate_and_copy_tuple(varnames);

if (ourvarnames == NULL)

goto cleanup;

if (freevars)

ourfreevars = validate_and_copy_tuple(freevars);

else

ourfreevars = PyTuple_New(0);

if (ourfreevars == NULL)

goto cleanup;

if (cellvars)

ourcellvars = validate_and_copy_tuple(cellvars);

else

ourcellvars = PyTuple_New(0);

if (ourcellvars == NULL)

goto cleanup;

co = (PyObject *) PyCode_New(argcount, nlocals, stacksize, flags,

code, consts, ournames, ourvarnames,

ourfreevars, ourcellvars, filename,

name, firstlineno, lnotab);

cleanup:

Py_XDECREF(ournames);

Py_XDECREF(ourvarnames);

Py_XDECREF(ourfreevars);

Py_XDECREF(ourcellvars);

return co;

}

static void

code_dealloc(PyCodeObject *co)

{

Py_XDECREF(co->co_code);

Py_XDECREF(co->co_consts);

Py_XDECREF(co->co_names);

Py_XDECREF(co->co_varnames);

Py_XDECREF(co->co_freevars);

Py_XDECREF(co->co_cellvars);

Py_XDECREF(co->co_filename);

Py_XDECREF(co->co_name);

Py_XDECREF(co->co_lnotab);

PyObject_DEL(co);

}

static PyObject *

code_repr(PyCodeObject *co)

{

char buf[500];

int lineno = -1;

char *filename = "???";

char *name = "???";

if (co->co_firstlineno != 0)

lineno = co->co_firstlineno;

if (co->co_filename && PyString_Check(co->co_filename))

filename = PyString_AS_STRING(co->co_filename);

if (co->co_name && PyString_Check(co->co_name))

name = PyString_AS_STRING(co->co_name);

PyOS_snprintf(buf, sizeof(buf),

"<code object %.100s at %p, file \"%.300s\", line %d>",

name, co, filename, lineno);

return PyString_FromString(buf);

}

static int

code_compare(PyCodeObject *co, PyCodeObject *cp)

{

int cmp;

cmp = PyObject_Compare(co->co_name, cp->co_name);

if (cmp) return cmp;

cmp = co->co_argcount - cp->co_argcount;

if (cmp) return (cmp<0)?-1:1;

cmp = co->co_nlocals - cp->co_nlocals;

if (cmp) return (cmp<0)?-1:1;

cmp = co->co_flags - cp->co_flags;

if (cmp) return (cmp<0)?-1:1;

cmp = co->co_firstlineno - cp->co_firstlineno;

if (cmp) return (cmp<0)?-1:1;

cmp = PyObject_Compare(co->co_code, cp->co_code);

if (cmp) return cmp;

cmp = PyObject_Compare(co->co_consts, cp->co_consts);

if (cmp) return cmp;

cmp = PyObject_Compare(co->co_names, cp->co_names);

if (cmp) return cmp;

cmp = PyObject_Compare(co->co_varnames, cp->co_varnames);

if (cmp) return cmp;

cmp = PyObject_Compare(co->co_freevars, cp->co_freevars);

if (cmp) return cmp;

cmp = PyObject_Compare(co->co_cellvars, cp->co_cellvars);

return cmp;

}

static long

code_hash(PyCodeObject *co)

{

long h, h0, h1, h2, h3, h4, h5, h6;

h0 = PyObject_Hash(co->co_name);

if (h0 == -1) return -1;

h1 = PyObject_Hash(co->co_code);

if (h1 == -1) return -1;

h2 = PyObject_Hash(co->co_consts);

if (h2 == -1) return -1;

h3 = PyObject_Hash(co->co_names);

if (h3 == -1) return -1;

h4 = PyObject_Hash(co->co_varnames);

if (h4 == -1) return -1;

h5 = PyObject_Hash(co->co_freevars);

if (h5 == -1) return -1;

h6 = PyObject_Hash(co->co_cellvars);

if (h6 == -1) return -1;

h = h0 ^ h1 ^ h2 ^ h3 ^ h4 ^ h5 ^ h6 ^

co->co_argcount ^ co->co_nlocals ^ co->co_flags;

if (h == -1) h = -2;

return h;

}

/* XXX code objects need to participate in GC? */

PyTypeObject PyCode_Type = {

PyObject_HEAD_INIT(&PyType_Type)

0,

"code",

sizeof(PyCodeObject),

0,

(destructor)code_dealloc, /* tp_dealloc */

0, /* tp_print */

0, /* tp_getattr */

0, /* tp_setattr */

(cmpfunc)code_compare, /* tp_compare */

(reprfunc)code_repr, /* tp_repr */

0, /* tp_as_number */

0, /* tp_as_sequence */

0, /* tp_as_mapping */

(hashfunc)code_hash, /* tp_hash */

0, /* tp_call */

0, /* tp_str */

PyObject_GenericGetAttr, /* tp_getattro */

0, /* tp_setattro */

0, /* tp_as_buffer */

Py_TPFLAGS_DEFAULT, /* tp_flags */

code_doc, /* tp_doc */

0, /* tp_traverse */

0, /* tp_clear */

0, /* tp_richcompare */

0, /* tp_weaklistoffset */

0, /* tp_iter */

0, /* tp_iternext */

0, /* tp_methods */

code_memberlist, /* tp_members */

0, /* tp_getset */

0, /* tp_base */

0, /* tp_dict */

0, /* tp_descr_get */

0, /* tp_descr_set */

0, /* tp_dictoffset */

0, /* tp_init */

0, /* tp_alloc */

code_new, /* tp_new */

};

#define NAME_CHARS \

"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyz"

/* all_name_chars(s): true iff all chars in s are valid NAME_CHARS */

static int

all_name_chars(unsigned char *s)

{

static char ok_name_char[256];

static unsigned char *name_chars = (unsigned char *)NAME_CHARS;

if (ok_name_char[*name_chars] == 0) {

unsigned char *p;

for (p = name_chars; *p; p++)

ok_name_char[*p] = 1;

}

while (*s) {

if (ok_name_char[*s++] == 0)

return 0;

}

return 1;

}

static void

intern_strings(PyObject *tuple)

{

int i;

for (i = PyTuple_GET_SIZE(tuple); --i >= 0; ) {

PyObject *v = PyTuple_GET_ITEM(tuple, i);

if (v == NULL || !PyString_CheckExact(v)) {

Py_FatalError("non-string found in code slot");

}

PyString_InternInPlace(&PyTuple_GET_ITEM(tuple, i));

}

}

/* Begin: Peephole optimizations ----------------------------------------- */

#define GETARG(arr, i) ((int)((arr[i+2]<<8) + arr[i+1]))

#define UNCONDITIONAL_JUMP(op) (op==JUMP_ABSOLUTE || op==JUMP_FORWARD)

#define ABSOLUTE_JUMP(op) (op==JUMP_ABSOLUTE || op==CONTINUE_LOOP)

#define GETJUMPTGT(arr, i) (GETARG(arr,i) + (ABSOLUTE_JUMP(arr[i]) ? 0 : i+3))

#define SETARG(arr, i, val) arr[i+2] = val>>8; arr[i+1] = val & 255

#define CODESIZE(op) (HAS_ARG(op) ? 3 : 1)

#define ISBASICBLOCK(blocks, start, bytes) (blocks[start]==blocks[start+bytes-1])

/* Replace LOAD_CONST c1. LOAD_CONST c2 ... LOAD_CONST cn BUILD_TUPLE n

with LOAD_CONST (c1, c2, ... cn).

The consts table must still be in list form so that the

new constant (c1, c2, ... cn) can be appended.

Called with codestr pointing to the first LOAD_CONST.

Bails out with no change if one or more of the LOAD_CONSTs is missing. */

static int

tuple_of_constants(unsigned char *codestr, int n, PyObject *consts)

{

PyObject *newconst, *constant;

int i, arg, len_consts;

/* Pre-conditions */

assert(PyList_CheckExact(consts));

assert(codestr[n*3] == BUILD_TUPLE);

assert(GETARG(codestr, (n*3)) == n);

for (i=0 ; i<n ; i++)

assert(codestr[i*3] == LOAD_CONST);

/* Buildup new tuple of constants */

newconst = PyTuple_New(n);

if (newconst == NULL)

return 0;

len_consts = PyList_GET_SIZE(consts);

for (i=0 ; i<n ; i++) {

arg = GETARG(codestr, (i*3));

assert(arg < len_consts);

constant = PyList_GET_ITEM(consts, arg);

Py_INCREF(constant);

PyTuple_SET_ITEM(newconst, i, constant);

}

/* Append folded constant onto consts */

if (PyList_Append(consts, newconst)) {

Py_DECREF(newconst);

return 0;

}

Py_DECREF(newconst);

/* Write NOPs over old LOAD_CONSTS and

add a new LOAD_CONST newconst on top of the BUILD_TUPLE n */

memset(codestr, NOP, n*3);

codestr[n*3] = LOAD_CONST;

SETARG(codestr, (n*3), len_consts);

return 1;

}

/* Replace LOAD_CONST c1. LOAD_CONST c2 BINOP

with LOAD_CONST binop(c1,c2)

The consts table must still be in list form so that the

new constant can be appended.

Called with codestr pointing to the first LOAD_CONST.

Abandons the transformation if the folding fails (i.e. 1+'a'). */

static int

fold_binops_on_constants(unsigned char *codestr, PyObject *consts)

{

PyObject *newconst, *v, *w;

int len_consts, opcode;

/* Pre-conditions */

assert(PyList_CheckExact(consts));

assert(codestr[0] == LOAD_CONST);

assert(codestr[3] == LOAD_CONST);

/* Create new constant */

v = PyList_GET_ITEM(consts, GETARG(codestr, 0));

w = PyList_GET_ITEM(consts, GETARG(codestr, 3));

opcode = codestr[6];

switch (opcode) {

case BINARY_POWER:

newconst = PyNumber_Power(v, w, Py_None);

break;

case BINARY_MULTIPLY:

newconst = PyNumber_Multiply(v, w);

break;

case BINARY_DIVIDE:

/* XXX care is needed to fold this operation statically:

the result might depend on the run-time presence of the -Qnew flag */

return 0;

case BINARY_TRUE_DIVIDE:

newconst = PyNumber_TrueDivide(v, w);

break;

case BINARY_FLOOR_DIVIDE:

newconst = PyNumber_FloorDivide(v, w);

break;

case BINARY_MODULO:

newconst = PyNumber_Remainder(v, w);

break;

case BINARY_ADD:

newconst = PyNumber_Add(v, w);

break;

case BINARY_SUBTRACT:

newconst = PyNumber_Subtract(v, w);

break;

case BINARY_SUBSCR:

newconst = PyObject_GetItem(v, w);

break;

case BINARY_LSHIFT:

newconst = PyNumber_Lshift(v, w);

break;

case BINARY_RSHIFT:

newconst = PyNumber_Rshift(v, w);

break;

case BINARY_AND:

newconst = PyNumber_And(v, w);

break;

case BINARY_XOR:

newconst = PyNumber_Xor(v, w);

break;

case BINARY_OR:

newconst = PyNumber_Or(v, w);

break;

default:

/* Called with an unknown opcode */

assert(0);

return 0;

}

if (newconst == NULL) {

PyErr_Clear();

return 0;

}

/* Append folded constant into consts table */

len_consts = PyList_GET_SIZE(consts);

if (PyList_Append(consts, newconst)) {

Py_DECREF(newconst);

return 0;

}

Py_DECREF(newconst);

/* Write NOP NOP NOP NOP LOAD_CONST newconst */

memset(codestr, NOP, 4);

codestr[4] = LOAD_CONST;

SETARG(codestr, 4, len_consts);

return 1;

}

static unsigned int *

markblocks(unsigned char *code, int len)

{

unsigned int *blocks = PyMem_Malloc(len*sizeof(int));

int i,j, opcode, blockcnt = 0;

if (blocks == NULL)

return NULL;

memset(blocks, 0, len*sizeof(int));

/* Mark labels in the first pass */

for (i=0 ; i<len ; i+=CODESIZE(opcode)) {

opcode = code[i];

switch (opcode) {

case FOR_ITER:

case JUMP_FORWARD:

case JUMP_IF_FALSE:

case JUMP_IF_TRUE:

case JUMP_ABSOLUTE:

case CONTINUE_LOOP:

case SETUP_LOOP:

case SETUP_EXCEPT:

case SETUP_FINALLY:

j = GETJUMPTGT(code, i);

blocks[j] = 1;

break;

}

}

/* Build block numbers in the second pass */

for (i=0 ; i<len ; i++) {

blockcnt += blocks[i]; /* increment blockcnt over labels */

blocks[i] = blockcnt;

}

return blocks;

}

/* Perform basic peephole optimizations to components of a code object.

The consts object should still be in list form to allow new constants

to be appended.

To keep the optimizer simple, it bails out (does nothing) for code

containing extended arguments or that has a length over 32,700. That

allows us to avoid overflow and sign issues. Likewise, it bails when

the lineno table has complex encoding for gaps >= 255.

Optimizations are restricted to simple transformations occuring within a

single basic block. All transformations keep the code size the same or

smaller. For those that reduce size, the gaps are initially filled with

NOPs. Later those NOPs are removed and the jump addresses retargeted in

a single pass. Line numbering is adjusted accordingly. */

static PyObject *

optimize_code(PyObject *code, PyObject* consts, PyObject *names, PyObject *lineno_obj)

{

int i, j, codelen, nops, h, adj;

int tgt, tgttgt, opcode;

unsigned char *codestr = NULL;

unsigned char *lineno;

int *addrmap = NULL;

int new_line, cum_orig_line, last_line, tabsiz;

int cumlc=0, lastlc=0; /* Count runs of consecutive LOAD_CONST codes */

unsigned int *blocks = NULL;

char *name;

/* Bail out if an exception is set */

if (PyErr_Occurred())

goto exitUnchanged;

/* Bypass optimization when the lineno table is too complex */

assert(PyString_Check(lineno_obj));

lineno = PyString_AS_STRING(lineno_obj);

tabsiz = PyString_GET_SIZE(lineno_obj);

if (memchr(lineno, 255, tabsiz) != NULL)

goto exitUnchanged;

/* Avoid situations where jump retargeting could overflow */

assert(PyString_Check(code));

codelen = PyString_Size(code);

if (codelen > 32700)

goto exitUnchanged;

/* Make a modifiable copy of the code string */

codestr = PyMem_Malloc(codelen);

if (codestr == NULL)

goto exitUnchanged;

codestr = memcpy(codestr, PyString_AS_STRING(code), codelen);

/* Mapping to new jump targets after NOPs are removed */

addrmap = PyMem_Malloc(codelen * sizeof(int));

if (addrmap == NULL)

goto exitUnchanged;

blocks = markblocks(codestr, codelen);

if (blocks == NULL)

goto exitUnchanged;

assert(PyList_Check(consts));

for (i=0 ; i<codelen ; i += CODESIZE(codestr[i])) {

opcode = codestr[i];

lastlc = cumlc;

cumlc = 0;

switch (opcode) {

/* Replace UNARY_NOT JUMP_IF_FALSE POP_TOP with

with JUMP_IF_TRUE POP_TOP */

case UNARY_NOT:

if (codestr[i+1] != JUMP_IF_FALSE ||

codestr[i+4] != POP_TOP ||

!ISBASICBLOCK(blocks,i,5))

continue;

tgt = GETJUMPTGT(codestr, (i+1));

if (codestr[tgt] != POP_TOP)

continue;

j = GETARG(codestr, i+1) + 1;

codestr[i] = JUMP_IF_TRUE;

SETARG(codestr, i, j);

codestr[i+3] = POP_TOP;

codestr[i+4] = NOP;

break;

/* not a is b --> a is not b

not a in b --> a not in b

not a is not b --> a is b

not a not in b --> a in b */

case COMPARE_OP:

j = GETARG(codestr, i);

if (j < 6 || j > 9 ||

codestr[i+3] != UNARY_NOT ||

!ISBASICBLOCK(blocks,i,4))

continue;

SETARG(codestr, i, (j^1));

codestr[i+3] = NOP;

break;

/* Replace LOAD_GLOBAL/LOAD_NAME None with LOAD_CONST None */

case LOAD_NAME:

case LOAD_GLOBAL:

j = GETARG(codestr, i);

name = PyString_AsString(PyTuple_GET_ITEM(names, j));

if (name == NULL || strcmp(name, "None") != 0)

continue;

for (j=0 ; j < PyList_GET_SIZE(consts) ; j++) {

if (PyList_GET_ITEM(consts, j) == Py_None) {

codestr[i] = LOAD_CONST;

SETARG(codestr, i, j);

cumlc = lastlc + 1;

break;

}

}

break;

/* Skip over LOAD_CONST trueconst JUMP_IF_FALSE xx POP_TOP */

case LOAD_CONST:

cumlc = lastlc + 1;

j = GETARG(codestr, i);

if (codestr[i+3] != JUMP_IF_FALSE ||

codestr[i+6] != POP_TOP ||

!ISBASICBLOCK(blocks,i,7) ||

!PyObject_IsTrue(PyList_GET_ITEM(consts, j)))

continue;

memset(codestr+i, NOP, 7);

cumlc = 0;

break;

/* Try to fold tuples of constants.

Skip over BUILD_SEQN 1 UNPACK_SEQN 1.

Replace BUILD_SEQN 2 UNPACK_SEQN 2 with ROT2.

Replace BUILD_SEQN 3 UNPACK_SEQN 3 with ROT3 ROT2. */

case BUILD_TUPLE:

j = GETARG(codestr, i);

h = i - 3 * j;

if (h >= 0 &&

j <= lastlc &&

ISBASICBLOCK(blocks, h, 3*(j+1)) &&

tuple_of_constants(&codestr[h], j, consts)) {

assert(codestr[i] == LOAD_CONST);

cumlc = 1;

break;

}

/* Intentional fallthrough */

case BUILD_LIST:

j = GETARG(codestr, i);

if (codestr[i+3] != UNPACK_SEQUENCE ||

!ISBASICBLOCK(blocks,i,6) ||

j != GETARG(codestr, i+3))

continue;

if (j == 1) {

memset(codestr+i, NOP, 6);

} else if (j == 2) {

codestr[i] = ROT_TWO;

memset(codestr+i+1, NOP, 5);

} else if (j == 3) {

codestr[i] = ROT_THREE;

codestr[i+1] = ROT_TWO;

memset(codestr+i+2, NOP, 4);

}

break;

/* Fold binary ops on constants.

LOAD_CONST c1 LOAD_CONST c2 BINOP --> LOAD_CONST binop(c1,c2) */

case BINARY_POWER:

case BINARY_MULTIPLY:

case BINARY_DIVIDE:

case BINARY_TRUE_DIVIDE:

case BINARY_FLOOR_DIVIDE:

case BINARY_MODULO:

case BINARY_ADD:

case BINARY_SUBTRACT:

case BINARY_SUBSCR:

case BINARY_LSHIFT:

case BINARY_RSHIFT:

case BINARY_AND:

case BINARY_XOR:

case BINARY_OR:

if (lastlc >= 2 &&

ISBASICBLOCK(blocks, i-6, 7) &&

fold_binops_on_constants(&codestr[i-6], consts)) {

i -= 2;

assert(codestr[i] == LOAD_CONST);

cumlc = 1;

}

break;

/* Simplify conditional jump to conditional jump where the

result of the first test implies the success of a similar

test or the failure of the opposite test.

Arises in code like:

"if a and b:"

"if a or b:"

"a and b or c"

"(a and b) and c"

x:JUMP_IF_FALSE y y:JUMP_IF_FALSE z --> x:JUMP_IF_FALSE z

x:JUMP_IF_FALSE y y:JUMP_IF_TRUE z --> x:JUMP_IF_FALSE y+3

where y+3 is the instruction following the second test.

*/

case JUMP_IF_FALSE:

case JUMP_IF_TRUE:

tgt = GETJUMPTGT(codestr, i);

j = codestr[tgt];

if (j == JUMP_IF_FALSE || j == JUMP_IF_TRUE) {

if (j == opcode) {

tgttgt = GETJUMPTGT(codestr, tgt) - i - 3;

SETARG(codestr, i, tgttgt);

} else {

tgt -= i;

SETARG(codestr, i, tgt);

}

break;

}

/* Intentional fallthrough */

/* Replace jumps to unconditional jumps */

case FOR_ITER:

case JUMP_FORWARD:

case JUMP_ABSOLUTE:

case CONTINUE_LOOP:

case SETUP_LOOP:

case SETUP_EXCEPT:

case SETUP_FINALLY:

tgt = GETJUMPTGT(codestr, i);

if (!UNCONDITIONAL_JUMP(codestr[tgt]))

continue;

tgttgt = GETJUMPTGT(codestr, tgt);

if (opcode == JUMP_FORWARD) /* JMP_ABS can go backwards */

opcode = JUMP_ABSOLUTE;

if (!ABSOLUTE_JUMP(opcode))

tgttgt -= i + 3; /* Calc relative jump addr */

if (tgttgt < 0) /* No backward relative jumps */

continue;

codestr[i] = opcode;

SETARG(codestr, i, tgttgt);

break;

case EXTENDED_ARG:

goto exitUnchanged;

/* Replace RETURN LOAD_CONST None RETURN with just RETURN */

case RETURN_VALUE:

if (i+4 >= codelen ||

codestr[i+4] != RETURN_VALUE ||

!ISBASICBLOCK(blocks,i,5))

continue;

memset(codestr+i+1, NOP, 4);

break;

}

}

/* Fixup linenotab */

for (i=0, nops=0 ; i<codelen ; i += CODESIZE(codestr[i])) {

addrmap[i] = i - nops;

if (codestr[i] == NOP)

nops++;

}

cum_orig_line = 0;

last_line = 0;

for (i=0 ; i < tabsiz ; i+=2) {

cum_orig_line += lineno[i];

new_line = addrmap[cum_orig_line];

assert (new_line - last_line < 255);

lineno[i] =((unsigned char)(new_line - last_line));

last_line = new_line;

}

/* Remove NOPs and fixup jump targets */

for (i=0, h=0 ; i<codelen ; ) {

opcode = codestr[i];

switch (opcode) {

case NOP:

i++;

continue;

case JUMP_ABSOLUTE:

case CONTINUE_LOOP:

j = addrmap[GETARG(codestr, i)];

SETARG(codestr, i, j);

break;

case FOR_ITER:

case JUMP_FORWARD:

case JUMP_IF_FALSE:

case JUMP_IF_TRUE:

case SETUP_LOOP:

case SETUP_EXCEPT:

case SETUP_FINALLY:

j = addrmap[GETARG(codestr, i) + i + 3] - addrmap[i] - 3;

SETARG(codestr, i, j);

break;

}

adj = CODESIZE(opcode);

while (adj--)

codestr[h++] = codestr[i++];

}

assert(h + nops == codelen);

code = PyString_FromStringAndSize((char *)codestr, h);

PyMem_Free(addrmap);

PyMem_Free(codestr);

PyMem_Free(blocks);

return code;

exitUnchanged:

if (blocks != NULL)

PyMem_Free(blocks);

if (addrmap != NULL)

PyMem_Free(addrmap);

if (codestr != NULL)

PyMem_Free(codestr);

Py_INCREF(code);

return code;

}

/* End: Peephole optimizations ----------------------------------------- */

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)

{

PyCodeObject *co;

int i;

/* Check argument types */

if (argcount < 0 || nlocals < 0 ||

code == NULL ||

consts == NULL || !PyTuple_Check(consts) ||

names == NULL || !PyTuple_Check(names) ||

varnames == NULL || !PyTuple_Check(varnames) ||

freevars == NULL || !PyTuple_Check(freevars) ||

cellvars == NULL || !PyTuple_Check(cellvars) ||

name == NULL || !PyString_Check(name) ||

filename == NULL || !PyString_Check(filename) ||

lnotab == NULL || !PyString_Check(lnotab) ||

!PyObject_CheckReadBuffer(code)) {

PyErr_BadInternalCall();

return NULL;

}

intern_strings(names);

intern_strings(varnames);

intern_strings(freevars);

intern_strings(cellvars);

/* Intern selected string constants */

for (i = PyTuple_Size(consts); --i >= 0; ) {

PyObject *v = PyTuple_GetItem(consts, i);

if (!PyString_Check(v))

continue;

if (!all_name_chars((unsigned char *)PyString_AS_STRING(v)))

continue;

PyString_InternInPlace(&PyTuple_GET_ITEM(consts, i));

}

co = PyObject_NEW(PyCodeObject, &PyCode_Type);

if (co != NULL) {

co->co_argcount = argcount;

co->co_nlocals = nlocals;

co->co_stacksize = stacksize;

co->co_flags = flags;

Py_INCREF(code);

co->co_code = code;

Py_INCREF(consts);

co->co_consts = consts;

Py_INCREF(names);

co->co_names = names;

Py_INCREF(varnames);

co->co_varnames = varnames;

Py_INCREF(freevars);

co->co_freevars = freevars;

Py_INCREF(cellvars);

co->co_cellvars = cellvars;

Py_INCREF(filename);

co->co_filename = filename;

Py_INCREF(name);

co->co_name = name;

co->co_firstlineno = firstlineno;

Py_INCREF(lnotab);

co->co_lnotab = lnotab;

if (PyTuple_GET_SIZE(freevars) == 0 &&

PyTuple_GET_SIZE(cellvars) == 0)

co->co_flags |= CO_NOFREE;

}

return co;

}

/* Data structure used internally */

/* The compiler uses two passes to generate bytecodes. The first pass

builds the symbol table. The second pass generates the bytecode.

The first pass uses a single symtable struct. The second pass uses

a compiling struct for each code block. The compiling structs

share a reference to the symtable.

The two passes communicate via symtable_load_symbols() and via

is_local() and is_global(). The former initializes several slots

in the compiling struct: c_varnames, c_locals, c_nlocals,

c_argcount, c_globals, and c_flags.

*/

/* All about c_lnotab.

c_lnotab is an array of unsigned bytes disguised as a Python string. Since

version 2.3, SET_LINENO opcodes are never generated and bytecode offsets are

mapped to source code line #s 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