Move peephole optimizer to separate file.
diff --git a/Python/peephole.c b/Python/peephole.c
new file mode 100644
index 0000000..1d94319
--- /dev/null
+++ b/Python/peephole.c
@@ -0,0 +1,615 @@
+/* Peehole optimizations for bytecode compiler. */
+
+#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"
+
+#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;
+ 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 int
+fold_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:
+ 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;
+ Py_ssize_t len_consts;
+ int 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 = (unsigned int *)PyMem_Malloc(len*sizeof(int));
+ int i,j, opcode, blockcnt = 0;
+
+ if (blocks == NULL) {
+ PyErr_NoMemory();
+ 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. */
+
+PyObject *
+PyCode_Optimize(PyObject *code, PyObject* consts, PyObject *names,
+ PyObject *lineno_obj)
+{
+ Py_ssize_t i, j, codelen;
+ int 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_CONSTs */
+ 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 = (unsigned char *)PyMem_Malloc(codelen);
+ if (codestr == NULL)
+ goto exitUnchanged;
+ codestr = (unsigned char *)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 = (int *)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;
+}