Backport r69961 to trunk, replacing JUMP_IF_{TRUE,FALSE} with
POP_JUMP_IF_{TRUE,FALSE} and JUMP_IF_{TRUE,FALSE}_OR_POP. This avoids executing
a POP_TOP on each conditional and sometimes allows the peephole optimizer to
skip a JUMP_ABSOLUTE entirely. It speeds up list comprehensions significantly.
diff --git a/Python/ceval.c b/Python/ceval.c
index 419ecfa..88b9d0e 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -764,8 +764,8 @@
/* OpCode prediction macros
Some opcodes tend to come in pairs thus making it possible to
predict the second code when the first is run. For example,
- COMPARE_OP is often followed by JUMP_IF_FALSE or JUMP_IF_TRUE. And,
- those opcodes are often followed by a POP_TOP.
+ GET_ITER is often followed by FOR_ITER. And FOR_ITER is often
+ followed by STORE_FAST or UNPACK_SEQUENCE.
Verifying the prediction costs a single high-speed test of a register
variable against a constant. If the pairing was good, then the
@@ -1110,7 +1110,6 @@
SETLOCAL(oparg, v);
goto fast_next_opcode;
- PREDICTED(POP_TOP);
case POP_TOP:
v = POP();
Py_DECREF(v);
@@ -2220,8 +2219,8 @@
Py_DECREF(w);
SET_TOP(x);
if (x == NULL) break;
- PREDICT(JUMP_IF_FALSE);
- PREDICT(JUMP_IF_TRUE);
+ PREDICT(POP_JUMP_IF_FALSE);
+ PREDICT(POP_JUMP_IF_TRUE);
continue;
case IMPORT_NAME:
@@ -2298,44 +2297,95 @@
JUMPBY(oparg);
goto fast_next_opcode;
- PREDICTED_WITH_ARG(JUMP_IF_FALSE);
- case JUMP_IF_FALSE:
- w = TOP();
+ PREDICTED_WITH_ARG(POP_JUMP_IF_FALSE);
+ case POP_JUMP_IF_FALSE:
+ w = POP();
if (w == Py_True) {
- PREDICT(POP_TOP);
+ Py_DECREF(w);
goto fast_next_opcode;
}
if (w == Py_False) {
- JUMPBY(oparg);
+ Py_DECREF(w);
+ JUMPTO(oparg);
goto fast_next_opcode;
}
err = PyObject_IsTrue(w);
+ Py_DECREF(w);
if (err > 0)
err = 0;
else if (err == 0)
- JUMPBY(oparg);
+ JUMPTO(oparg);
else
break;
continue;
- PREDICTED_WITH_ARG(JUMP_IF_TRUE);
- case JUMP_IF_TRUE:
- w = TOP();
+ PREDICTED_WITH_ARG(POP_JUMP_IF_TRUE);
+ case POP_JUMP_IF_TRUE:
+ w = POP();
if (w == Py_False) {
- PREDICT(POP_TOP);
+ Py_DECREF(w);
goto fast_next_opcode;
}
if (w == Py_True) {
- JUMPBY(oparg);
+ Py_DECREF(w);
+ JUMPTO(oparg);
+ goto fast_next_opcode;
+ }
+ err = PyObject_IsTrue(w);
+ Py_DECREF(w);
+ if (err > 0) {
+ err = 0;
+ JUMPTO(oparg);
+ }
+ else if (err == 0)
+ ;
+ else
+ break;
+ continue;
+
+ case JUMP_IF_FALSE_OR_POP:
+ w = TOP();
+ if (w == Py_True) {
+ STACKADJ(-1);
+ Py_DECREF(w);
+ goto fast_next_opcode;
+ }
+ if (w == Py_False) {
+ JUMPTO(oparg);
+ goto fast_next_opcode;
+ }
+ err = PyObject_IsTrue(w);
+ if (err > 0) {
+ STACKADJ(-1);
+ Py_DECREF(w);
+ err = 0;
+ }
+ else if (err == 0)
+ JUMPTO(oparg);
+ else
+ break;
+ continue;
+
+ case JUMP_IF_TRUE_OR_POP:
+ w = TOP();
+ if (w == Py_False) {
+ STACKADJ(-1);
+ Py_DECREF(w);
+ goto fast_next_opcode;
+ }
+ if (w == Py_True) {
+ JUMPTO(oparg);
goto fast_next_opcode;
}
err = PyObject_IsTrue(w);
if (err > 0) {
err = 0;
- JUMPBY(oparg);
+ JUMPTO(oparg);
}
- else if (err == 0)
- ;
+ else if (err == 0) {
+ STACKADJ(-1);
+ Py_DECREF(w);
+ }
else
break;
continue;
diff --git a/Python/compile.c b/Python/compile.c
index a252bd1..69321ae 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -836,11 +836,15 @@
return 1;
case JUMP_FORWARD:
- case JUMP_IF_FALSE:
- case JUMP_IF_TRUE:
+ case JUMP_IF_TRUE_OR_POP: /* -1 if jump not taken */
+ case JUMP_IF_FALSE_OR_POP: /* "" */
case JUMP_ABSOLUTE:
return 0;
+ case POP_JUMP_IF_FALSE:
+ case POP_JUMP_IF_TRUE:
+ return -1;
+
case LOAD_GLOBAL:
return 1;
@@ -1499,12 +1503,10 @@
if (next == NULL)
return 0;
VISIT(c, expr, e->v.IfExp.test);
- ADDOP_JREL(c, JUMP_IF_FALSE, next);
- ADDOP(c, POP_TOP);
+ ADDOP_JABS(c, POP_JUMP_IF_FALSE, next);
VISIT(c, expr, e->v.IfExp.body);
ADDOP_JREL(c, JUMP_FORWARD, end);
compiler_use_next_block(c, next);
- ADDOP(c, POP_TOP);
VISIT(c, expr, e->v.IfExp.orelse);
compiler_use_next_block(c, end);
return 1;
@@ -1597,9 +1599,6 @@
end = compiler_new_block(c);
if (end == NULL)
return 0;
- next = compiler_new_block(c);
- if (next == NULL)
- return 0;
constant = expr_constant(s->v.If.test);
/* constant = 0: "if 0"
@@ -1611,15 +1610,21 @@
} else if (constant == 1) {
VISIT_SEQ(c, stmt, s->v.If.body);
} else {
+ if (s->v.If.orelse) {
+ next = compiler_new_block(c);
+ if (next == NULL)
+ return 0;
+ }
+ else
+ next = end;
VISIT(c, expr, s->v.If.test);
- ADDOP_JREL(c, JUMP_IF_FALSE, next);
- ADDOP(c, POP_TOP);
+ ADDOP_JABS(c, POP_JUMP_IF_FALSE, next);
VISIT_SEQ(c, stmt, s->v.If.body);
ADDOP_JREL(c, JUMP_FORWARD, end);
- compiler_use_next_block(c, next);
- ADDOP(c, POP_TOP);
- if (s->v.If.orelse)
+ if (s->v.If.orelse) {
+ compiler_use_next_block(c, next);
VISIT_SEQ(c, stmt, s->v.If.orelse);
+ }
}
compiler_use_next_block(c, end);
return 1;
@@ -1693,8 +1698,7 @@
so we need to set an extra line number. */
c->u->u_lineno_set = false;
VISIT(c, expr, s->v.While.test);
- ADDOP_JREL(c, JUMP_IF_FALSE, anchor);
- ADDOP(c, POP_TOP);
+ ADDOP_JABS(c, POP_JUMP_IF_FALSE, anchor);
}
VISIT_SEQ(c, stmt, s->v.While.body);
ADDOP_JABS(c, JUMP_ABSOLUTE, loop);
@@ -1705,7 +1709,6 @@
if (constant == -1) {
compiler_use_next_block(c, anchor);
- ADDOP(c, POP_TOP);
ADDOP(c, POP_BLOCK);
}
compiler_pop_fblock(c, LOOP, loop);
@@ -1826,20 +1829,17 @@
[tb, val, exc] L1: DUP )
[tb, val, exc, exc] <evaluate E1> )
[tb, val, exc, exc, E1] COMPARE_OP EXC_MATCH ) only if E1
- [tb, val, exc, 1-or-0] JUMP_IF_FALSE L2 )
- [tb, val, exc, 1] POP )
+ [tb, val, exc, 1-or-0] POP_JUMP_IF_FALSE L2 )
[tb, val, exc] POP
[tb, val] <assign to V1> (or POP if no V1)
[tb] POP
[] <code for S1>
JUMP_FORWARD L0
- [tb, val, exc, 0] L2: POP
- [tb, val, exc] DUP
+ [tb, val, exc] L2: DUP
.............................etc.......................
- [tb, val, exc, 0] Ln+1: POP
- [tb, val, exc] END_FINALLY # re-raise exception
+ [tb, val, exc] Ln+1: END_FINALLY # re-raise exception
[] L0: <next statement>
@@ -1881,8 +1881,7 @@
ADDOP(c, DUP_TOP);
VISIT(c, expr, handler->v.ExceptHandler.type);
ADDOP_I(c, COMPARE_OP, PyCmp_EXC_MATCH);
- ADDOP_JREL(c, JUMP_IF_FALSE, except);
- ADDOP(c, POP_TOP);
+ ADDOP_JABS(c, POP_JUMP_IF_FALSE, except);
}
ADDOP(c, POP_TOP);
if (handler->v.ExceptHandler.name) {
@@ -1895,8 +1894,6 @@
VISIT_SEQ(c, stmt, handler->v.ExceptHandler.body);
ADDOP_JREL(c, JUMP_FORWARD, end);
compiler_use_next_block(c, except);
- if (handler->v.ExceptHandler.type)
- ADDOP(c, POP_TOP);
}
ADDOP(c, END_FINALLY);
compiler_use_next_block(c, orelse);
@@ -2084,8 +2081,7 @@
end = compiler_new_block(c);
if (end == NULL)
return 0;
- ADDOP_JREL(c, JUMP_IF_TRUE, end);
- ADDOP(c, POP_TOP);
+ ADDOP_JABS(c, POP_JUMP_IF_TRUE, end);
ADDOP_O(c, LOAD_GLOBAL, assertion_error, names);
if (s->v.Assert.msg) {
VISIT(c, expr, s->v.Assert.msg);
@@ -2095,7 +2091,6 @@
ADDOP_I(c, RAISE_VARARGS, 1);
}
compiler_use_next_block(c, end);
- ADDOP(c, POP_TOP);
return 1;
}
@@ -2473,9 +2468,9 @@
assert(e->kind == BoolOp_kind);
if (e->v.BoolOp.op == And)
- jumpi = JUMP_IF_FALSE;
+ jumpi = JUMP_IF_FALSE_OR_POP;
else
- jumpi = JUMP_IF_TRUE;
+ jumpi = JUMP_IF_TRUE_OR_POP;
end = compiler_new_block(c);
if (end == NULL)
return 0;
@@ -2484,8 +2479,7 @@
assert(n >= 0);
for (i = 0; i < n; ++i) {
VISIT(c, expr, (expr_ty)asdl_seq_GET(s, i));
- ADDOP_JREL(c, jumpi, end);
- ADDOP(c, POP_TOP)
+ ADDOP_JABS(c, jumpi, end);
}
VISIT(c, expr, (expr_ty)asdl_seq_GET(s, n));
compiler_use_next_block(c, end);
@@ -2543,9 +2537,8 @@
ADDOP_I(c, COMPARE_OP,
cmpop((cmpop_ty)(asdl_seq_GET(
e->v.Compare.ops, i - 1))));
- ADDOP_JREL(c, JUMP_IF_FALSE, cleanup);
+ ADDOP_JABS(c, JUMP_IF_FALSE_OR_POP, cleanup);
NEXT_BLOCK(c);
- ADDOP(c, POP_TOP);
if (i < (n - 1))
VISIT(c, expr,
(expr_ty)asdl_seq_GET(e->v.Compare.comparators, i));
@@ -2636,9 +2629,8 @@
for (i = 0; i < n; i++) {
expr_ty e = (expr_ty)asdl_seq_GET(l->ifs, i);
VISIT(c, expr, e);
- ADDOP_JREL(c, JUMP_IF_FALSE, if_cleanup);
+ ADDOP_JABS(c, POP_JUMP_IF_FALSE, if_cleanup);
NEXT_BLOCK(c);
- ADDOP(c, POP_TOP);
}
if (++gen_index < asdl_seq_LEN(generators))
@@ -2652,12 +2644,7 @@
compiler_use_next_block(c, skip);
}
- for (i = 0; i < n; i++) {
- ADDOP_I(c, JUMP_FORWARD, 1);
- if (i == 0)
- compiler_use_next_block(c, if_cleanup);
- ADDOP(c, POP_TOP);
- }
+ compiler_use_next_block(c, if_cleanup);
ADDOP_JABS(c, JUMP_ABSOLUTE, start);
compiler_use_next_block(c, anchor);
@@ -2720,10 +2707,9 @@
for (i = 0; i < n; i++) {
expr_ty e = (expr_ty)asdl_seq_GET(ge->ifs, i);
VISIT(c, expr, e);
- ADDOP_JREL(c, JUMP_IF_FALSE, if_cleanup);
+ ADDOP_JABS(c, POP_JUMP_IF_FALSE, if_cleanup);
NEXT_BLOCK(c);
- ADDOP(c, POP_TOP);
- }
+ }
if (++gen_index < asdl_seq_LEN(generators))
if (!compiler_genexp_generator(c, generators, gen_index, elt))
@@ -2737,13 +2723,7 @@
compiler_use_next_block(c, skip);
}
- for (i = 0; i < n; i++) {
- ADDOP_I(c, JUMP_FORWARD, 1);
- if (i == 0)
- compiler_use_next_block(c, if_cleanup);
-
- ADDOP(c, POP_TOP);
- }
+ compiler_use_next_block(c, if_cleanup);
ADDOP_JABS(c, JUMP_ABSOLUTE, start);
compiler_use_next_block(c, anchor);
ADDOP(c, POP_BLOCK);
diff --git a/Python/import.c b/Python/import.c
index b00986c..98b8dce 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -72,9 +72,11 @@
Python 2.6a0: 62151 (peephole optimizations and STORE_MAP opcode)
Python 2.6a1: 62161 (WITH_CLEANUP optimization)
Python 2.7a0: 62171 (optimize list comprehensions/change LIST_APPEND)
+ Python 2.7a0: 62181 (optimize conditional branches:
+ introduce POP_JUMP_IF_FALSE and POP_JUMP_IF_TRUE)
.
*/
-#define MAGIC (62171 | ((long)'\r'<<16) | ((long)'\n'<<24))
+#define MAGIC (62181 | ((long)'\r'<<16) | ((long)'\n'<<24))
/* Magic word as global; note that _PyImport_Init() can change the
value of this global to accommodate for alterations of how the
diff --git a/Python/peephole.c b/Python/peephole.c
index e9da377..a3dda9c 100644
--- a/Python/peephole.c
+++ b/Python/peephole.c
@@ -13,7 +13,12 @@
#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 CONDITIONAL_JUMP(op) (op==POP_JUMP_IF_FALSE || op==POP_JUMP_IF_TRUE \
+ || op==JUMP_IF_FALSE_OR_POP || op==JUMP_IF_TRUE_OR_POP)
+#define ABSOLUTE_JUMP(op) (op==JUMP_ABSOLUTE || op==CONTINUE_LOOP \
+ || op==POP_JUMP_IF_FALSE || op==POP_JUMP_IF_TRUE \
+ || op==JUMP_IF_FALSE_OR_POP || op==JUMP_IF_TRUE_OR_POP)
+#define JUMPS_ON_TRUE(op) (op==POP_JUMP_IF_TRUE || op==JUMP_IF_TRUE_OR_POP)
#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)
@@ -245,8 +250,10 @@
switch (opcode) {
case FOR_ITER:
case JUMP_FORWARD:
- case JUMP_IF_FALSE:
- case JUMP_IF_TRUE:
+ case JUMP_IF_FALSE_OR_POP:
+ case JUMP_IF_TRUE_OR_POP:
+ case POP_JUMP_IF_FALSE:
+ case POP_JUMP_IF_TRUE:
case JUMP_ABSOLUTE:
case CONTINUE_LOOP:
case SETUP_LOOP:
@@ -338,29 +345,24 @@
assert(PyList_Check(consts));
for (i=0 ; i<codelen ; i += CODESIZE(codestr[i])) {
+ reoptimize_current:
opcode = codestr[i];
lastlc = cumlc;
cumlc = 0;
switch (opcode) {
-
- /* Replace UNARY_NOT JUMP_IF_FALSE POP_TOP with
- with JUMP_IF_TRUE POP_TOP */
+ /* Replace UNARY_NOT POP_JUMP_IF_FALSE
+ with POP_JUMP_IF_TRUE */
case UNARY_NOT:
- if (codestr[i+1] != JUMP_IF_FALSE ||
- codestr[i+4] != POP_TOP ||
- !ISBASICBLOCK(blocks,i,5))
+ if (codestr[i+1] != POP_JUMP_IF_FALSE
+ || !ISBASICBLOCK(blocks,i,4))
continue;
- tgt = GETJUMPTGT(codestr, (i+1));
- if (codestr[tgt] != POP_TOP)
- continue;
- j = GETARG(codestr, i+1) + 1;
- codestr[i] = JUMP_IF_TRUE;
+ j = GETARG(codestr, i+1);
+ codestr[i] = POP_JUMP_IF_TRUE;
SETARG(codestr, i, j);
- codestr[i+3] = POP_TOP;
- codestr[i+4] = NOP;
- break;
+ codestr[i+3] = NOP;
+ goto reoptimize_current;
/* not a is b --> a is not b
not a in b --> a not in b
@@ -400,16 +402,16 @@
break;
/* Skip over LOAD_CONST trueconst
- JUMP_IF_FALSE xx POP_TOP */
+ POP_JUMP_IF_FALSE xx. This improves
+ "while 1" performance. */
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) ||
+ if (codestr[i+3] != POP_JUMP_IF_FALSE ||
+ !ISBASICBLOCK(blocks,i,6) ||
!PyObject_IsTrue(PyList_GET_ITEM(consts, j)))
continue;
- memset(codestr+i, NOP, 7);
+ memset(codestr+i, NOP, 6);
cumlc = 0;
break;
@@ -498,27 +500,49 @@
"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
+ x:JUMP_IF_FALSE_OR_POP y y:JUMP_IF_FALSE_OR_POP z
+ --> x:JUMP_IF_FALSE_OR_POP z
+ x:JUMP_IF_FALSE_OR_POP y y:JUMP_IF_TRUE_OR_POP z
+ --> x:POP_JUMP_IF_FALSE y+3
where y+3 is the instruction following the second test.
*/
- case JUMP_IF_FALSE:
- case JUMP_IF_TRUE:
+ case JUMP_IF_FALSE_OR_POP:
+ case JUMP_IF_TRUE_OR_POP:
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;
+ if (CONDITIONAL_JUMP(j)) {
+ /* NOTE: all possible jumps here are
+ absolute! */
+ if (JUMPS_ON_TRUE(j) == JUMPS_ON_TRUE(opcode)) {
+ /* The second jump will be
+ taken iff the first is. */
+ tgttgt = GETJUMPTGT(codestr, tgt);
+ /* The current opcode inherits
+ its target's stack behaviour */
+ codestr[i] = j;
SETARG(codestr, i, tgttgt);
+ goto reoptimize_current;
} else {
- tgt -= i;
- SETARG(codestr, i, tgt);
+ /* The second jump is not taken
+ if the first is (so jump past
+ it), and all conditional
+ jumps pop their argument when
+ they're not taken (so change
+ the first jump to pop its
+ argument when it's taken). */
+ if (JUMPS_ON_TRUE(opcode))
+ codestr[i] = POP_JUMP_IF_TRUE;
+ else
+ codestr[i] = POP_JUMP_IF_FALSE;
+ SETARG(codestr, i, (tgt + 3));
+ goto reoptimize_current;
}
- break;
}
- /* Intentional fallthrough */
+ /* Intentional fallthrough */
/* Replace jumps to unconditional jumps */
+ case POP_JUMP_IF_FALSE:
+ case POP_JUMP_IF_TRUE:
case FOR_ITER:
case JUMP_FORWARD:
case JUMP_ABSOLUTE:
@@ -591,14 +615,16 @@
case JUMP_ABSOLUTE:
case CONTINUE_LOOP:
+ case POP_JUMP_IF_FALSE:
+ case POP_JUMP_IF_TRUE:
+ case JUMP_IF_FALSE_OR_POP:
+ case JUMP_IF_TRUE_OR_POP:
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:
