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/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: