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gh-102859: Remove JUMP_IF_FALSE_OR_POP and JUMP_IF_TRUE_OR_POP (#102870)

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Irit Katriel 2023-03-22 18:10:48 +00:00 • committed by GitHub
parent 04adf2df39
commit 3468c768ce
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15 changed files with 235 additions and 437 deletions
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192
Python/compile.c
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@ -4241,19 +4241,18 @@ compiler_boolop(struct compiler *c, expr_ty e)
location loc = LOC(e);
assert(e->kind == BoolOp_kind);
if (e->v.BoolOp.op == And)
jumpi = JUMP_IF_FALSE_OR_POP;
jumpi = POP_JUMP_IF_FALSE;
else
jumpi = JUMP_IF_TRUE_OR_POP;
jumpi = POP_JUMP_IF_TRUE;
NEW_JUMP_TARGET_LABEL(c, end);
s = e->v.BoolOp.values;
n = asdl_seq_LEN(s) - 1;
assert(n >= 0);
for (i = 0; i < n; ++i) {
VISIT(c, expr, (expr_ty)asdl_seq_GET(s, i));
ADDOP_I(c, loc, COPY, 1);
ADDOP_JUMP(c, loc, jumpi, end);
NEW_JUMP_TARGET_LABEL(c, next);
USE_LABEL(c, next);
ADDOP(c, loc, POP_TOP);
}
VISIT(c, expr, (expr_ty)asdl_seq_GET(s, n));
@ -4558,7 +4557,9 @@ compiler_compare(struct compiler *c, expr_ty e)
ADDOP_I(c, loc, SWAP, 2);
ADDOP_I(c, loc, COPY, 2);
ADDOP_COMPARE(c, loc, asdl_seq_GET(e->v.Compare.ops, i));
ADDOP_JUMP(c, loc, JUMP_IF_FALSE_OR_POP, cleanup);
ADDOP_I(c, loc, COPY, 1);
ADDOP_JUMP(c, loc, POP_JUMP_IF_FALSE, cleanup);
ADDOP(c, loc, POP_TOP);
}
VISIT(c, expr, (expr_ty)asdl_seq_GET(e->v.Compare.comparators, n));
ADDOP_COMPARE(c, loc, asdl_seq_GET(e->v.Compare.ops, n));
@ -7836,21 +7837,6 @@ normalize_jumps_in_block(cfg_builder *g, basicblock *b) {
case POP_JUMP_IF_TRUE:
reversed_opcode = POP_JUMP_IF_FALSE;
break;
case JUMP_IF_TRUE_OR_POP:
case JUMP_IF_FALSE_OR_POP:
if (!is_forward) {
/* As far as we can tell, the compiler never emits
* these jumps with a backwards target. If/when this
* exception is raised, we have found a use case for
* a backwards version of this jump (or to replace
* it with the sequence (COPY 1, POP_JUMP_IF_T/F, POP)
*/
PyErr_Format(PyExc_SystemError,
"unexpected %s jumping backwards",
last->i_opcode == JUMP_IF_TRUE_OR_POP ?
"JUMP_IF_TRUE_OR_POP" : "JUMP_IF_FALSE_OR_POP");
}
return SUCCESS;
}
if (is_forward) {
return SUCCESS;
@ -9143,21 +9129,30 @@ optimize_basic_block(PyObject *const_cache, basicblock *bb, PyObject *consts)
assert(PyList_CheckExact(consts));
struct cfg_instr nop;
INSTR_SET_OP0(&nop, NOP);
struct cfg_instr *target;
struct cfg_instr *target = &nop;
int opcode = 0;
int oparg = 0;
int nextop = 0;
for (int i = 0; i < bb->b_iused; i++) {
struct cfg_instr *inst = &bb->b_instr[i];
int oparg = inst->i_oparg;
int nextop = i+1 < bb->b_iused ? bb->b_instr[i+1].i_opcode : 0;
if (HAS_TARGET(inst->i_opcode)) {
assert(inst->i_target->b_iused > 0);
target = &inst->i_target->b_instr[0];
assert(!IS_ASSEMBLER_OPCODE(target->i_opcode));
bool is_copy_of_load_const = (opcode == LOAD_CONST &&
inst->i_opcode == COPY &&
inst->i_oparg == 1);
if (! is_copy_of_load_const) {
opcode = inst->i_opcode;
oparg = inst->i_oparg;
if (HAS_TARGET(opcode)) {
assert(inst->i_target->b_iused > 0);
target = &inst->i_target->b_instr[0];
assert(!IS_ASSEMBLER_OPCODE(target->i_opcode));
}
else {
target = &nop;
}
}
else {
target = &nop;
}
assert(!IS_ASSEMBLER_OPCODE(inst->i_opcode));
switch (inst->i_opcode) {
nextop = i+1 < bb->b_iused ? bb->b_instr[i+1].i_opcode : 0;
assert(!IS_ASSEMBLER_OPCODE(opcode));
switch (opcode) {
/* Remove LOAD_CONST const; conditional jump */
case LOAD_CONST:
{
@ -9167,7 +9162,7 @@ optimize_basic_block(PyObject *const_cache, basicblock *bb, PyObject *consts)
switch(nextop) {
case POP_JUMP_IF_FALSE:
case POP_JUMP_IF_TRUE:
cnt = get_const_value(inst->i_opcode, oparg, consts);
cnt = get_const_value(opcode, oparg, consts);
if (cnt == NULL) {
goto error;
}
@ -9185,28 +9180,8 @@ optimize_basic_block(PyObject *const_cache, basicblock *bb, PyObject *consts)
INSTR_SET_OP0(&bb->b_instr[i + 1], NOP);
}
break;
case JUMP_IF_FALSE_OR_POP:
case JUMP_IF_TRUE_OR_POP:
cnt = get_const_value(inst->i_opcode, oparg, consts);
if (cnt == NULL) {
goto error;
}
is_true = PyObject_IsTrue(cnt);
Py_DECREF(cnt);
if (is_true == -1) {
goto error;
}
jump_if_true = nextop == JUMP_IF_TRUE_OR_POP;
if (is_true == jump_if_true) {
bb->b_instr[i+1].i_opcode = JUMP;
}
else {
INSTR_SET_OP0(inst, NOP);
INSTR_SET_OP0(&bb->b_instr[i + 1], NOP);
}
break;
case IS_OP:
cnt = get_const_value(inst->i_opcode, oparg, consts);
cnt = get_const_value(opcode, oparg, consts);
if (cnt == NULL) {
goto error;
}
@ -9252,65 +9227,6 @@ optimize_basic_block(PyObject *const_cache, basicblock *bb, PyObject *consts)
}
}
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:
"a and b or c"
"(a and b) and c"
"(a or b) or c"
"(a or b) and c"
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+1
where y+1 is the instruction following the second test.
*/
case JUMP_IF_FALSE_OR_POP:
switch (target->i_opcode) {
case POP_JUMP_IF_FALSE:
i -= jump_thread(inst, target, POP_JUMP_IF_FALSE);
break;
case JUMP:
case JUMP_IF_FALSE_OR_POP:
i -= jump_thread(inst, target, JUMP_IF_FALSE_OR_POP);
break;
case JUMP_IF_TRUE_OR_POP:
case POP_JUMP_IF_TRUE:
if (inst->i_loc.lineno == target->i_loc.lineno) {
// We don't need to bother checking for loops here,
// since a block's b_next cannot point to itself:
assert(inst->i_target != inst->i_target->b_next);
inst->i_opcode = POP_JUMP_IF_FALSE;
inst->i_target = inst->i_target->b_next;
--i;
}
break;
}
break;
case JUMP_IF_TRUE_OR_POP:
switch (target->i_opcode) {
case POP_JUMP_IF_TRUE:
i -= jump_thread(inst, target, POP_JUMP_IF_TRUE);
break;
case JUMP:
case JUMP_IF_TRUE_OR_POP:
i -= jump_thread(inst, target, JUMP_IF_TRUE_OR_POP);
break;
case JUMP_IF_FALSE_OR_POP:
case POP_JUMP_IF_FALSE:
if (inst->i_loc.lineno == target->i_loc.lineno) {
// We don't need to bother checking for loops here,
// since a block's b_next cannot point to itself:
assert(inst->i_target != inst->i_target->b_next);
inst->i_opcode = POP_JUMP_IF_TRUE;
inst->i_target = inst->i_target->b_next;
--i;
}
break;
}
break;
case POP_JUMP_IF_NOT_NONE:
case POP_JUMP_IF_NONE:
switch (target->i_opcode) {
@ -9398,6 +9314,52 @@ inline_small_exit_blocks(basicblock *bb) {
return 0;
}
static int
remove_redundant_nops_and_pairs(basicblock *entryblock)
{
bool done = false;
while (! done) {
done = true;
struct cfg_instr *prev_instr = NULL;
struct cfg_instr *instr = NULL;
for (basicblock *b = entryblock; b != NULL; b = b->b_next) {
remove_redundant_nops(b);
if (IS_LABEL(b->b_label)) {
/* this block is a jump target, forget instr */
instr = NULL;
}
for (int i = 0; i < b->b_iused; i++) {
prev_instr = instr;
instr = &b->b_instr[i];
int prev_opcode = prev_instr ? prev_instr->i_opcode : 0;
int prev_oparg = prev_instr ? prev_instr->i_oparg : 0;
int opcode = instr->i_opcode;
bool is_redundant_pair = false;
if (opcode == POP_TOP) {
if (prev_opcode == LOAD_CONST) {
is_redundant_pair = true;
}
else if (prev_opcode == COPY && prev_oparg == 1) {
is_redundant_pair = true;
}
}
if (is_redundant_pair) {
INSTR_SET_OP0(prev_instr, NOP);
INSTR_SET_OP0(instr, NOP);
done = false;
}
}
if ((instr && is_jump(instr)) || !BB_HAS_FALLTHROUGH(b)) {
instr = NULL;
}
}
}
return SUCCESS;
}
static int
remove_redundant_nops(basicblock *bb) {
/* Remove NOPs when legal to do so. */
@ -9636,9 +9598,9 @@ optimize_cfg(cfg_builder *g, PyObject *consts, PyObject *const_cache)
assert(no_empty_basic_blocks(g));
for (basicblock *b = g->g_entryblock; b != NULL; b = b->b_next) {
RETURN_IF_ERROR(optimize_basic_block(const_cache, b, consts));
remove_redundant_nops(b);
assert(b->b_predecessors == 0);
}
RETURN_IF_ERROR(remove_redundant_nops_and_pairs(g->g_entryblock));
for (basicblock *b = g->g_entryblock; b != NULL; b = b->b_next) {
RETURN_IF_ERROR(inline_small_exit_blocks(b));
}