/*

* This file compiles an abstract syntax tree (AST) into Python bytecode.

*

* The primary entry point is PyAST_Compile(), which returns a

* PyCodeObject. The compiler makes several passes to build the code

* object:

* 1. Checks for future statements. See future.c

* 2. Builds a symbol table. See symtable.c.

* 3. Generate code for basic blocks. See compiler_mod() in this file.

* 4. Assemble the basic blocks into final code. See assemble() in

* this file.

*

* Note that compiler_mod() suggests module, but the module ast type

* (mod_ty) has cases for expressions and interactive statements.

*

* CAUTION: The VISIT_* macros abort the current function when they encounter

* a problem. So don't invoke them when there is memory which needs to be

* released. Code blocks are OK, as the compiler structure takes care of

* releasing those.

*/

#include "Python.h"

#include "Python-ast.h"

#include "node.h"

#include "pyarena.h"

#include "ast.h"

#include "code.h"

#include "compile.h"

#include "symtable.h"

#include "opcode.h"

int Py_OptimizeFlag = 0;

/*

ISSUES:

character encodings aren't handled

ref leaks in interpreter when press return on empty line

opcode_stack_effect() function should be reviewed since stack depth bugs

could be really hard to find later.

Dead code is being generated (i.e. after unconditional jumps).

*/

#define DEFAULT_BLOCK_SIZE 16

#define DEFAULT_BLOCKS 8

#define DEFAULT_CODE_SIZE 128

#define DEFAULT_LNOTAB_SIZE 16

struct instr {

int i_jabs : 1;

int i_jrel : 1;

int i_hasarg : 1;

unsigned char i_opcode;

int i_oparg;

struct basicblock_ *i_target; /* target block (if jump instruction) */

int i_lineno;

};

typedef struct basicblock_ {

/* next block in the list of blocks for a unit (don't confuse with

* b_next) */

struct basicblock_ *b_list;

/* number of instructions used */

int b_iused;

/* length of instruction array (b_instr) */

int b_ialloc;

/* pointer to an array of instructions, initially NULL */

struct instr *b_instr;

/* If b_next is non-NULL, it is a pointer to the next

block reached by normal control flow. */

struct basicblock_ *b_next;

/* b_seen is used to perform a DFS of basicblocks. */

int b_seen : 1;

/* b_return is true if a RETURN_VALUE opcode is inserted. */

int b_return : 1;

/* depth of stack upon entry of block, computed by stackdepth() */

int b_startdepth;

/* instruction offset for block, computed by assemble_jump_offsets() */

int b_offset;

} basicblock;

/* fblockinfo tracks the current frame block.

A frame block is used to handle loops, try/except, and try/finally.

It's called a frame block to distinguish it from a basic block in the

compiler IR.

*/

enum fblocktype { LOOP, EXCEPT, FINALLY_TRY, FINALLY_END };

struct fblockinfo {

enum fblocktype fb_type;

basicblock *fb_block;

};

/* The following items change on entry and exit of code blocks.

They must be saved and restored when returning to a block.

*/

struct compiler_unit {

PySTEntryObject *u_ste;

PyObject *u_name;

/* The following fields are dicts that map objects to

the index of them in co_XXX. The index is used as

the argument for opcodes that refer to those collections.

*/

PyObject *u_consts; /* all constants */

PyObject *u_names; /* all names */

PyObject *u_varnames; /* local variables */

PyObject *u_cellvars; /* cell variables */

PyObject *u_freevars; /* free variables */

PyObject *u_private; /* for private name mangling */

int u_argcount; /* number of arguments for block */

basicblock *u_blocks; /* pointer to list of blocks */

basicblock *u_curblock; /* pointer to current block */

int u_tmpname; /* temporary variables for list comps */

int u_nfblocks;

struct fblockinfo u_fblock[CO_MAXBLOCKS];

int u_firstlineno; /* the first lineno of the block */

int u_lineno; /* the lineno for the current stmt */

bool u_lineno_set; /* boolean to indicate whether instr

has been generated with current lineno */

};

/* This struct captures the global state of a compilation.

The u pointer points to the current compilation unit, while units

for enclosing blocks are stored in c_stack. The u and c_stack are

managed by compiler_enter_scope() and compiler_exit_scope().

*/

struct compiler {

const char *c_filename;

struct symtable *c_st;

PyFutureFeatures *c_future; /* pointer to module's __future__ */

PyCompilerFlags *c_flags;

int c_interactive;

int c_nestlevel;

struct compiler_unit *u; /* compiler state for current block */

PyObject *c_stack; /* Python list holding compiler_unit ptrs */

char *c_encoding; /* source encoding (a borrowed reference) */

PyArena *c_arena; /* pointer to memory allocation arena */

};

struct assembler {

PyObject *a_bytecode; /* string containing bytecode */

int a_offset; /* offset into bytecode */

int a_nblocks; /* number of reachable blocks */

basicblock **a_postorder; /* list of blocks in dfs postorder */

PyObject *a_lnotab; /* string containing lnotab */

int a_lnotab_off; /* offset into lnotab */

int a_lineno; /* last lineno of emitted instruction */

int a_lineno_off; /* bytecode offset of last lineno */

};

static int compiler_enter_scope(struct compiler *, identifier, void *, int);

static void compiler_free(struct compiler *);

static basicblock *compiler_new_block(struct compiler *);

static int compiler_next_instr(struct compiler *, basicblock *);

static int compiler_addop(struct compiler *, int);

static int compiler_addop_o(struct compiler *, int, PyObject *, PyObject *);

static int compiler_addop_i(struct compiler *, int, int);

static int compiler_addop_j(struct compiler *, int, basicblock *, int);

static void compiler_use_block(struct compiler *, basicblock *);

static basicblock *compiler_use_new_block(struct compiler *);

static int compiler_error(struct compiler *, const char *);

static int compiler_nameop(struct compiler *, identifier, expr_context_ty);

static PyCodeObject *compiler_mod(struct compiler *, mod_ty);

static int compiler_visit_stmt(struct compiler *, stmt_ty);

static int compiler_visit_keyword(struct compiler *, keyword_ty);

static int compiler_visit_expr(struct compiler *, expr_ty);

static int compiler_augassign(struct compiler *, stmt_ty);

static int compiler_visit_slice(struct compiler *, slice_ty,

expr_context_ty);

static int compiler_push_fblock(struct compiler *, enum fblocktype,

basicblock *);

static void compiler_pop_fblock(struct compiler *, enum fblocktype,

basicblock *);

static int inplace_binop(struct compiler *, operator_ty);

static int expr_constant(expr_ty e);

static PyCodeObject *assemble(struct compiler *, int addNone);

static PyObject *__doc__;

PyObject *

_Py_Mangle(PyObject *private, PyObject *ident)

{

/* Name mangling: __private becomes _classname__private.

This is independent from how the name is used. */

const char *p, *name = PyString_AsString(ident);

char *buffer;

size_t nlen, plen;

if (private == NULL || name == NULL || name[0] != '_' || name[1] != '_') {

Py_INCREF(ident);

return ident;

}

p = PyString_AsString(private);

nlen = strlen(name);

if (name[nlen-1] == '_' && name[nlen-2] == '_') {

Py_INCREF(ident);

return ident; /* Don't mangle __whatever__ */

}

/* Strip leading underscores from class name */

while (*p == '_')

p++;

if (*p == '\0') {

Py_INCREF(ident);

return ident; /* Don't mangle if class is just underscores */

}

plen = strlen(p);

ident = PyString_FromStringAndSize(NULL, 1 + nlen + plen);

if (!ident)

return 0;

/* ident = "_" + p[:plen] + name # i.e. 1+plen+nlen bytes */

buffer = PyString_AS_STRING(ident);

buffer[0] = '_';

strncpy(buffer+1, p, plen);

strcpy(buffer+1+plen, name);

return ident;

}

static int

compiler_init(struct compiler *c)

{

memset(c, 0, sizeof(struct compiler));

c->c_stack = PyList_New(0);

if (!c->c_stack)

return 0;

return 1;

}

PyCodeObject *

PyAST_Compile(mod_ty mod, const char *filename, PyCompilerFlags *flags,

PyArena *arena)

{

struct compiler c;

PyCodeObject *co = NULL;

PyCompilerFlags local_flags;

int merged;

if (!__doc__) {

__doc__ = PyString_InternFromString("__doc__");

if (!__doc__)

goto error;

}

if (!compiler_init(&c))

goto error;

c.c_filename = filename;

c.c_arena = arena;

c.c_future = PyFuture_FromAST(mod, filename);

if (c.c_future == NULL)

goto error;

if (!flags) {

local_flags.cf_flags = 0;

flags = &local_flags;

}

merged = c.c_future->ff_features | flags->cf_flags;

c.c_future->ff_features = merged;

flags->cf_flags = merged;

c.c_flags = flags;

c.c_nestlevel = 0;

c.c_st = PySymtable_Build(mod, filename, c.c_future);

if (c.c_st == NULL) {

if (!PyErr_Occurred())

PyErr_SetString(PyExc_SystemError, "no symtable");

goto error;

}

/* XXX initialize to NULL for now, need to handle */

c.c_encoding = NULL;

co = compiler_mod(&c, mod);

error:

compiler_free(&c);

return co;

}

PyCodeObject *

PyNode_Compile(struct _node *n, const char *filename)

{

PyCodeObject *co = NULL;

PyArena *arena;

arena = PyArena_New();

mod_ty mod = PyAST_FromNode(n, NULL, filename, arena);

if (mod)

co = PyAST_Compile(mod, filename, NULL, arena);

PyArena_Free(arena);

return co;

}

static void

compiler_free(struct compiler *c)

{

if (c->c_st)

PySymtable_Free(c->c_st);

if (c->c_future)

PyMem_Free(c->c_future);

Py_DECREF(c->c_stack);

}

static PyObject *

list2dict(PyObject *list)

{

int i, n;

PyObject *v, *k, *dict = PyDict_New();

n = PyList_Size(list);

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

v = PyInt_FromLong(i);

if (!v) {

Py_DECREF(dict);

return NULL;

}

k = PyList_GET_ITEM(list, i);

k = Py_BuildValue("(OO)", k, k->ob_type);

if (k == NULL || PyDict_SetItem(dict, k, v) < 0) {

Py_XDECREF(k);

Py_DECREF(v);

Py_DECREF(dict);

return NULL;

}

Py_DECREF(k);

Py_DECREF(v);

}

return dict;

}

/* Return new dict containing names from src that match scope(s).

src is a symbol table dictionary. If the scope of a name matches

either scope_type or flag is set, insert it into the new dict. The

values are integers, starting at offset and increasing by one for

each key.

*/

static PyObject *

dictbytype(PyObject *src, int scope_type, int flag, int offset)

{

int pos = 0, i = offset, scope;

PyObject *k, *v, *dest = PyDict_New();

assert(offset >= 0);

if (dest == NULL)

return NULL;

while (PyDict_Next(src, &pos, &k, &v)) {

/* XXX this should probably be a macro in symtable.h */

assert(PyInt_Check(v));

scope = (PyInt_AS_LONG(v) >> SCOPE_OFF) & SCOPE_MASK;

if (scope == scope_type || PyInt_AS_LONG(v) & flag) {

PyObject *tuple, *item = PyInt_FromLong(i);

if (item == NULL) {

Py_DECREF(dest);

return NULL;

}

i++;

tuple = Py_BuildValue("(OO)", k, k->ob_type);

if (!tuple || PyDict_SetItem(dest, tuple, item) < 0) {

Py_DECREF(item);

Py_DECREF(dest);

Py_XDECREF(tuple);

return NULL;

}

Py_DECREF(item);

Py_DECREF(tuple);

}

}

return dest;

}

/* 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.

Also works for BUILD_LIST when followed by an "in" or "not in" test.

*/

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 || codestr[n*3] == BUILD_LIST);

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').

If the new constant is a sequence, only folds when the size

is below a threshold value. That keeps pyc files from

becoming large in the presence of code like: (None,)*1000.

*/

static int

fold_binops_on_constants(unsigned char *codestr, PyObject *consts)

{

PyObject *newconst, *v, *w;

int len_consts, opcode, size;

/* 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:

/* Cannot fold this operation statically since

the result can 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 */

PyErr_Format(PyExc_SystemError,

"unexpected binary operation %d on a constant",

opcode);

return 0;

}

if (newconst == NULL) {

PyErr_Clear();

return 0;

}

size = PyObject_Size(newconst);

if (size == -1)

PyErr_Clear();

else if (size > 20) {

Py_DECREF(newconst);

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 int

fold_unaryops_on_constants(unsigned char *codestr, PyObject *consts)

{

PyObject *newconst=NULL, *v;

int len_consts, opcode;

/* Pre-conditions */

assert(PyList_CheckExact(consts));

assert(codestr[0] == LOAD_CONST);

/* Create new constant */

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

opcode = codestr[3];

switch (opcode) {

case UNARY_NEGATIVE:

/* Preserve the sign of -0.0 */

if (PyObject_IsTrue(v) == 1)

newconst = PyNumber_Negative(v);

break;

case UNARY_CONVERT:

newconst = PyObject_Repr(v);

break;

case UNARY_INVERT:

newconst = PyNumber_Invert(v);

break;

default:

/* Called with an unknown opcode */

PyErr_Format(PyExc_SystemError,

"unexpected unary operation %d on a constant",

opcode);

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 LOAD_CONST newconst */

codestr[0] = NOP;

codestr[1] = LOAD_CONST;

SETARG(codestr, 1, 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 = (unsigned char*)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);

/* Verify that RETURN_VALUE terminates the codestring. This allows

the various transformation patterns to look ahead several

instructions without additional checks to make sure they are not

looking beyond the end of the code string.

*/

if (codestr[codelen-1] != RETURN_VALUE)

goto exitUnchanged;

/* 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 (includes a case for lists

which are only used for "in" and "not in" tests).

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:

case BUILD_LIST:

j = GETARG(codestr, i);

h = i - 3 * j;

if (h >= 0 &&

j <= lastlc &&

((opcode == BUILD_TUPLE &&

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

(opcode == BUILD_LIST &&

codestr[i+3]==COMPARE_OP &&

ISBASICBLOCK(blocks, h, 3*(j+2)) &&

(GETARG(codestr,i+3)==6 ||

GETARG(codestr,i+3)==7))) &&

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

assert(codestr[i] == LOAD_CONST);

cumlc = 1;

break;

}

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_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;

/* Fold unary ops on constants.

LOAD_CONST c1 UNARY_OP --> LOAD_CONST unary_op(c) */

case UNARY_NEGATIVE:

case UNARY_CONVERT:

case UNARY_INVERT:

if (lastlc >= 1 &&

ISBASICBLOCK(blocks, i-3, 4) &&

fold_unaryops_on_constants(&codestr[i-3], 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 ----------------------------------------- */

/*

Leave this debugging code for just a little longer.

static void

compiler_display_symbols(PyObject *name, PyObject *symbols)

{

PyObject *key, *value;

int flags, pos = 0;

fprintf(stderr, "block %s\n", PyString_AS_STRING(name));

while (PyDict_Next(symbols, &pos, &key, &value)) {

flags = PyInt_AsLong(value);

fprintf(stderr, "var %s:", PyString_AS_STRING(key));

if (flags & DEF_GLOBAL)