mirrors/cpython
1
0
Fork 0
mirror of https://github.com/python/cpython.git synced 2025-07-07 19:35:27 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 8

gh-126835: Move optimization of constant sequence creation from codegen to CFG (#129426)

Browse source 
Codegen phase has an optimization that transforms
```
LOAD_CONST x
LOAD_CONST y
LOAD_CONXT z
BUILD_LIST/BUILD_SET (3)
```
->
```
BUILD_LIST/BUILD_SET (0)
LOAD_CONST (x, y, z)
LIST_EXTEND/SET_UPDATE 1
```
This optimization has now been moved to CFG phase to make #128802 work.


Co-authored-by: Irit Katriel <1055913+iritkatriel@users.noreply.github.com>
Co-authored-by: Yan Yanchii <yyanchiy@gmail.com>
This commit is contained in:
Kirill Podoprigora 2025-02-01 11:39:44 +00:00 • committed by GitHub
parent d89a5f6a6e
commit 7d0521d5fc
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
3 changed files with 73 additions and 49 deletions
Download patch file Download diff file Expand all files Collapse all files

75
Python/flowgraph.c
View file

@ -1336,6 +1336,17 @@ add_const(PyObject *newconst, PyObject *consts, PyObject *const_cache)
return (int)index;
}
static bool
is_constant_sequence(cfg_instr *inst, int n)
{
for (int i = 0; i < n; i++) {
if(!loads_const(inst[i].i_opcode)) {
return false;
}
}
return true;
}
/* 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
@ -1353,10 +1364,8 @@ fold_tuple_on_constants(PyObject *const_cache,
assert(inst[n].i_opcode == BUILD_TUPLE);
assert(inst[n].i_oparg == n);
for (int i = 0; i < n; i++) {
if (!loads_const(inst[i].i_opcode)) {
return SUCCESS;
}
if (!is_constant_sequence(inst, n)) {
return SUCCESS;
}
/* Buildup new tuple of constants */
@ -1384,6 +1393,56 @@ fold_tuple_on_constants(PyObject *const_cache,
return SUCCESS;
}
#define MIN_CONST_SEQUENCE_SIZE 3
/* Replace LOAD_CONST c1, LOAD_CONST c2 ... LOAD_CONST cN, BUILD_LIST N
with BUILD_LIST 0, LOAD_CONST (c1, c2, ... cN), LIST_EXTEND 1,
or BUILD_SET & SET_UPDATE respectively.
*/
static int
optimize_if_const_list_or_set(PyObject *const_cache, cfg_instr* inst, int n, PyObject *consts)
{
assert(PyDict_CheckExact(const_cache));
assert(PyList_CheckExact(consts));
assert(inst[n].i_oparg == n);
int build = inst[n].i_opcode;
assert(build == BUILD_LIST || build == BUILD_SET);
int extend = build == BUILD_LIST ? LIST_EXTEND : SET_UPDATE;
if (n < MIN_CONST_SEQUENCE_SIZE || !is_constant_sequence(inst, n)) {
return SUCCESS;
}
PyObject *newconst = PyTuple_New(n);
if (newconst == NULL) {
return ERROR;
}
for (int i = 0; i < n; i++) {
int op = inst[i].i_opcode;
int arg = inst[i].i_oparg;
PyObject *constant = get_const_value(op, arg, consts);
if (constant == NULL) {
return ERROR;
}
PyTuple_SET_ITEM(newconst, i, constant);
}
if (build == BUILD_SET) {
PyObject *frozenset = PyFrozenSet_New(newconst);
if (frozenset == NULL) {
return ERROR;
}
Py_SETREF(newconst, frozenset);
}
int index = add_const(newconst, consts, const_cache);
RETURN_IF_ERROR(index);
INSTR_SET_OP1(&inst[0], build, 0);
for (int i = 1; i < n - 1; i++) {
INSTR_SET_OP0(&inst[i], NOP);
}
INSTR_SET_OP1(&inst[n-1], LOAD_CONST, index);
INSTR_SET_OP1(&inst[n], extend, 1);
return SUCCESS;
}
#define VISITED (-1)
// Replace an arbitrary run of SWAPs and NOPs with an optimal one that has the
@ -1751,6 +1810,14 @@ optimize_basic_block(PyObject *const_cache, basicblock *bb, PyObject *consts)
}
}
break;
case BUILD_LIST:
case BUILD_SET:
if (i >= oparg) {
if (optimize_if_const_list_or_set(const_cache, inst-oparg, oparg, consts) < 0) {
goto error;
}
}
break;
case POP_JUMP_IF_NOT_NONE:
case POP_JUMP_IF_NONE:
switch (target->i_opcode) {