/* * 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:   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).    XXX(nnorwitz): not sure this is still true*/ #define DEFAULT_BLOCK_SIZE 16#define DEFAULT_BLOCKS 8#define DEFAULT_CODE_SIZE 128#define DEFAULT_LNOTAB_SIZE 16 struct instr {	unsigned i_jabs : 1;	unsigned i_jrel : 1;	unsigned 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_ {    /* Each basicblock in a compilation unit is linked via b_list in the       reverse order that the block are allocated.  b_list points to the next       block, not to be confused with b_next, which is next by control flow. */	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. */	unsigned b_seen : 1;	/* b_return is true if a RETURN_VALUE opcode is inserted. */	unsigned 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 thecompiler 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 */     /* Pointer to the most recently allocated block.  By following b_list       members, you can reach all early allocated blocks. */	basicblock *u_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 unitsfor enclosing blocks are stored in c_stack.	The u and c_stack aremanaged 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;	 /* true if in interactive mode */	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 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 *);/* Returns true if there is a loop on the fblock stack. */static int compiler_in_loop(struct compiler *); static int inplace_binop(struct compiler *, operator_ty);static int expr_constant(expr_ty e); static int compiler_with(struct compiler *, stmt_ty); static PyCodeObject *assemble(struct compiler *, int addNone);static PyObject *__doc__; PyObject *_Py_Mangle(PyObject *privateobj, 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 (privateobj == NULL || !PyString_Check(privateobj) ||	    name == NULL || name[0] != '_' || name[1] != '_') {		Py_INCREF(ident);		return ident;	}	p = PyString_AsString(privateobj);	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 intcompiler_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__)			return NULL;	} 	if (!compiler_init(&c))		return NULL;	c.c_filename = filename;	c.c_arena = arena;	c.c_future = PyFuture_FromAST(mod, filename);	if (c.c_future == NULL)		goto finally;	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 finally;	} 	/* XXX initialize to NULL for now, need to handle */	c.c_encoding = NULL; 	co = compiler_mod(&c, mod);  finally:	compiler_free(&c);	assert(co || PyErr_Occurred());	return co;} PyCodeObject *PyNode_Compile(struct _node *n, const char *filename){	PyCodeObject *co = NULL;	mod_ty mod;	PyArena *arena = PyArena_New();	if (!arena)		return NULL;	mod = PyAST_FromNode(n, NULL, filename, arena);	if (mod)		co = PyAST_Compile(mod, filename, NULL, arena);	PyArena_Free(arena);	return co;} static voidcompiler_free(struct compiler *c){	if (c->c_st)		PySymtable_Free(c->c_st);	if (c->c_future)		PyObject_Free(c->c_future);	Py_DECREF(c->c_stack);} static PyObject *list2dict(PyObject *list){	Py_ssize_t i, n;	PyObject *v, *k;	PyObject *dict = PyDict_New();	if (!dict) return NULL; 	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 = PyTuple_Pack(2, 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 matcheseither scope_type or flag is set, insert it into the new dict.	Thevalues are integers, starting at offset and increasing by one foreach key.*/ static PyObject *dictbytype(PyObject *src, int scope_type, int flag, int offset){	Py_ssize_t 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 = PyTuple_Pack(2, 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 inttuple_of_constants(unsigned char *codestr, int n, PyObject *consts){	PyObject *newconst, *constant;	Py_ssize_t 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 intfold_binops_on_constants(unsigned char *codestr, PyObject *consts){	PyObject *newconst, *v, *w;	Py_ssize_t len_consts, size;	int 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:			/* 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:

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