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gh-134584: Decref elimination for float ops in the JIT #134588

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Merged
Fidget-Spinner merged 27 commits into from
Jun 17, 2025
Merged

gh-134584: Decref elimination for float ops in the JIT #134588

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9466417
Skip refcounting where possible for common float ops
Fidget-Spinner May 23, 2025
ad03b1e
Add for common list ops
Fidget-Spinner May 23, 2025
7f90d0c
Fix test, rename
Fidget-Spinner May 23, 2025
a42b434
Remove list optimizations to minimize PR
Fidget-Spinner May 23, 2025
f456740
📜🤖 Added by blurb_it.
blurb-it[bot] May 23, 2025
16f9dee
Merge remote-tracking branch 'upstream/main' into decref_elimination_…
Fidget-Spinner May 27, 2025
5c429b6
Rename things to make things clearer
Fidget-Spinner May 27, 2025
1535133
Revert "Rename things to make things clearer"
Fidget-Spinner May 27, 2025
8f62067
Massive refactor from JitOptSymbol to JitRef
Fidget-Spinner May 28, 2025
a158835
refactor more
Fidget-Spinner May 28, 2025
e77f842
fix debug build
Fidget-Spinner May 28, 2025
01004c2
lint
Fidget-Spinner May 28, 2025
24f98d5
Merge remote-tracking branch 'upstream/main' into decref_elimination_…
Fidget-Spinner May 28, 2025
0189413
fix upstream
Fidget-Spinner May 28, 2025
4a386bf
reduce diff
Fidget-Spinner May 28, 2025
ac034a0
fix for FT
Fidget-Spinner May 28, 2025
b6e467e
fix failing tests
Fidget-Spinner May 28, 2025
3a3fa9d
Fix for disabled GIL
Fidget-Spinner May 29, 2025
ab1ad9c
fix on FT again
Fidget-Spinner May 29, 2025
5d82489
Try fix windows
Fidget-Spinner May 29, 2025
4d9a68e
Apply code review suggestions from Tomas
Fidget-Spinner Jun 4, 2025
2bbd47a
call the functions sym instead of ref
Fidget-Spinner Jun 4, 2025
2d779c4
rename jitref functions
Fidget-Spinner Jun 4, 2025
b74e160
Address review
Fidget-Spinner Jun 4, 2025
3ebcc20
Update comment
Fidget-Spinner Jun 4, 2025
673d5c8
Merge remote-tracking branch 'upstream/main' into decref_elimination_…
Fidget-Spinner Jun 17, 2025
914f1ff
Fix changes from upstream (no more casts)
Fidget-Spinner Jun 17, 2025
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Rename things to make things clearer
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@Fidget-Spinner
Fidget-Spinner committed May 27, 2025
commit 5c429b60831de05ecb3ba21e9ec3dcee50de724f
18 changes: 8 additions & 10 deletions Include/internal/pycore_optimizer.h
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Original file line number Diff line number Diff line change
Expand Up @@ -180,8 +180,8 @@ typedef enum _JitSymType {
JIT_SYM_TRUTHINESS_TAG = 9,
} JitSymType;

#define DONT_SKIP_REFCOUNT 0
#define SKIP_REFCOUNT 1
#define WE_MIGHT_BE_THE_ONLY_STRONG_REF 0
#define SOMEONE_ELSE_HAS_A_VALID_STRONG_REF 1

typedef struct _jit_opt_known_class {
struct {
Expand Down Expand Up @@ -231,11 +231,9 @@ typedef struct {
typedef union _jit_opt_symbol {
struct {
uint8_t tag;
// Whether this object skips refcount on the stack
// (using the _PyStackRef API), or not.
// 0 - normal refcounting
// 1 - skip refcounting
int8_t skip_refcount;
// Whether this object has a strong reference
// being held to it by someone else.
int8_t strong_ref_held_by_someone_else;
};
JitOptKnownClass cls;
JitOptKnownValue value;
Expand Down Expand Up @@ -308,9 +306,9 @@ extern JitOptSymbol *_Py_uop_sym_tuple_getitem(JitOptContext *ctx, JitOptSymbol
extern int _Py_uop_sym_tuple_length(JitOptSymbol *sym);
extern JitOptSymbol *_Py_uop_sym_new_truthiness(JitOptContext *ctx, JitOptSymbol *value, bool truthy);

extern void _Py_uop_sym_set_dont_skip_refcount(JitOptContext *ctx, JitOptSymbol *sym);
extern bool _Py_uop_sym_is_skip_refcount(JitOptContext *ctx, JitOptSymbol *sym);
extern void _Py_uop_sym_set_skip_refcount(JitOptContext *ctx, JitOptSymbol *sym);
extern void _Py_uop_sym_set_strong_ref_might_be_this_sym(JitOptContext *ctx, JitOptSymbol *sym);
extern bool _Py_uop_sym_is_strong_ref_held_by_someone_else(JitOptContext *ctx, JitOptSymbol *sym);
extern void _Py_uop_sym_set_strong_ref_is_held_by_someone_else(JitOptContext *ctx, JitOptSymbol *sym);

extern void _Py_uop_abstractcontext_init(JitOptContext *ctx);
extern void _Py_uop_abstractcontext_fini(JitOptContext *ctx);
Expand Down
6 changes: 3 additions & 3 deletions Python/optimizer_analysis.c
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Original file line number Diff line number Diff line change
Expand Up @@ -342,9 +342,9 @@ remove_globals(_PyInterpreterFrame *frame, _PyUOpInstruction *buffer,
#define sym_tuple_length _Py_uop_sym_tuple_length
#define sym_is_immortal _Py_uop_sym_is_immortal
#define sym_new_truthiness _Py_uop_sym_new_truthiness
#define sym_set_skip_refcount _Py_uop_sym_set_skip_refcount
#define sym_set_dont_skip_refcount _Py_uop_sym_set_dont_skip_refcount
#define sym_is_skip_refcount _Py_uop_sym_is_skip_refcount
#define sym_set_strong_ref_is_held_by_someone_else _Py_uop_sym_set_strong_ref_is_held_by_someone_else
#define sym_set_strong_ref_might_be_this_sym _Py_uop_sym_set_strong_ref_might_be_this_sym
#define sym_is_strong_ref_held_by_someone_else _Py_uop_sym_is_strong_ref_held_by_someone_else

static int
optimize_to_bool(
Expand Down
14 changes: 7 additions & 7 deletions Python/optimizer_bytecodes.c
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Original file line number Diff line number Diff line change
Expand Up @@ -80,24 +80,24 @@ dummy_func(void) {
if (sym_is_null(value)) {
ctx->done = true;
}
sym_set_dont_skip_refcount(ctx, value);
sym_set_strong_ref_might_be_this_sym(ctx, value);
}

op(_LOAD_FAST, (-- value)) {
value = GETLOCAL(oparg);
sym_set_dont_skip_refcount(ctx, value);
sym_set_strong_ref_might_be_this_sym(ctx, value);
}

op(_LOAD_FAST_BORROW, (-- value)) {
value = GETLOCAL(oparg);
sym_set_skip_refcount(ctx, value);
sym_set_strong_ref_is_held_by_someone_else(ctx, value);
}

op(_LOAD_FAST_AND_CLEAR, (-- value)) {
value = GETLOCAL(oparg);
JitOptSymbol *temp = sym_new_null(ctx);
GETLOCAL(oparg) = temp;
sym_set_dont_skip_refcount(ctx, value);
sym_set_strong_ref_might_be_this_sym(ctx, value);
}

op(_STORE_FAST, (value --)) {
Expand Down Expand Up @@ -301,7 +301,7 @@ dummy_func(void) {
res = sym_new_type(ctx, &PyFloat_Type);
}
// TODO (gh-134584): Move this to the optimizer generator.
if (sym_is_skip_refcount(ctx, left) && sym_is_skip_refcount(ctx, right)) {
if (sym_is_strong_ref_held_by_someone_else(ctx, left) && sym_is_strong_ref_held_by_someone_else(ctx, right)) {
REPLACE_OP(this_instr, op_without_decref_inputs[opcode], oparg, 0);
}
}
Expand All @@ -325,7 +325,7 @@ dummy_func(void) {
res = sym_new_type(ctx, &PyFloat_Type);
}
// TODO (gh-134584): Move this to the optimizer generator.
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@markshannon markshannon Jun 4, 2025

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I don't think we want to do this "automatically". What we do want to do is to move almost all the Py_DECREFs into a few ops like POP_TOP and "manually" optimize those few ops.

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@Fidget-Spinner Fidget-Spinner Jun 4, 2025

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I put a comment and said to refactor this.

if (sym_is_skip_refcount(ctx, left) && sym_is_skip_refcount(ctx, right)) {
if (sym_is_strong_ref_held_by_someone_else(ctx, left) && sym_is_strong_ref_held_by_someone_else(ctx, right)) {
REPLACE_OP(this_instr, op_without_decref_inputs[opcode], oparg, 0);
}
}
Expand All @@ -349,7 +349,7 @@ dummy_func(void) {
res = sym_new_type(ctx, &PyFloat_Type);
}
// TODO (gh-134584): Move this to the optimizer generator.
if (sym_is_skip_refcount(ctx, left) && sym_is_skip_refcount(ctx, right)) {
if (sym_is_strong_ref_held_by_someone_else(ctx, left) && sym_is_strong_ref_held_by_someone_else(ctx, right)) {
REPLACE_OP(this_instr, op_without_decref_inputs[opcode], oparg, 0);
}
}
Expand Down
14 changes: 7 additions & 7 deletions Python/optimizer_cases.c.h
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31 changes: 16 additions & 15 deletions Python/optimizer_symbols.c
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Original file line number Diff line number Diff line change
Expand Up @@ -99,7 +99,7 @@ sym_new(JitOptContext *ctx)
}
ctx->t_arena.ty_curr_number++;
self->tag = JIT_SYM_UNKNOWN_TAG;
self->skip_refcount = DONT_SKIP_REFCOUNT;
self->strong_ref_held_by_someone_else = WE_MIGHT_BE_THE_ONLY_STRONG_REF;
return self;
}

Expand All @@ -109,7 +109,7 @@ static void make_const(JitOptSymbol *sym, PyObject *val)
sym->value.value = Py_NewRef(val);
// Constants don't need to be refcounted, as they are always
// kept alive by co_consts.
sym->skip_refcount = SKIP_REFCOUNT;
sym->strong_ref_held_by_someone_else = SOMEONE_ELSE_HAS_A_VALID_STRONG_REF;
}

static inline void
Expand Down Expand Up @@ -386,22 +386,23 @@ _Py_uop_sym_set_non_null(JitOptContext *ctx, JitOptSymbol *sym)
}

void
_Py_uop_sym_set_skip_refcount(JitOptContext *ctx, JitOptSymbol *sym)
_Py_uop_sym_set_strong_ref_is_held_by_someone_else(JitOptContext *ctx, JitOptSymbol *sym)
{
sym->skip_refcount = SKIP_REFCOUNT;
sym->strong_ref_held_by_someone_else = SOMEONE_ELSE_HAS_A_VALID_STRONG_REF;
}

void
_Py_uop_sym_set_dont_skip_refcount(JitOptContext *ctx, JitOptSymbol *sym)
_Py_uop_sym_set_strong_ref_might_be_this_sym(JitOptContext *ctx, JitOptSymbol *sym)
{
sym->skip_refcount = DONT_SKIP_REFCOUNT;
sym->strong_ref_held_by_someone_else = WE_MIGHT_BE_THE_ONLY_STRONG_REF;
}

bool
_Py_uop_sym_is_skip_refcount(JitOptContext *ctx, JitOptSymbol *sym)
_Py_uop_sym_is_strong_ref_held_by_someone_else(JitOptContext *ctx, JitOptSymbol *sym)
{
assert(sym->skip_refcount == SKIP_REFCOUNT || sym->skip_refcount == DONT_SKIP_REFCOUNT);
return sym->skip_refcount == SKIP_REFCOUNT;
assert(sym->strong_ref_held_by_someone_else == SOMEONE_ELSE_HAS_A_VALID_STRONG_REF ||
sym->strong_ref_held_by_someone_else == WE_MIGHT_BE_THE_ONLY_STRONG_REF);
return sym->strong_ref_held_by_someone_else == SOMEONE_ELSE_HAS_A_VALID_STRONG_REF;
}


Expand Down Expand Up @@ -794,7 +795,7 @@ _Py_uop_symbols_test(PyObject *Py_UNUSED(self), PyObject *Py_UNUSED(ignored))
if (sym == NULL) {
goto fail;
}
TEST_PREDICATE(!_Py_uop_sym_is_skip_refcount(ctx, sym), "top is refcounted");
TEST_PREDICATE(!_Py_uop_sym_is_strong_ref_held_by_someone_else(ctx, sym), "top is refcounted");
TEST_PREDICATE(!_Py_uop_sym_is_null(sym), "top is NULL");
TEST_PREDICATE(!_Py_uop_sym_is_not_null(sym), "top is not NULL");
TEST_PREDICATE(!_Py_uop_sym_matches_type(sym, &PyLong_Type), "top matches a type");
Expand Down Expand Up @@ -843,7 +844,7 @@ _Py_uop_symbols_test(PyObject *Py_UNUSED(self), PyObject *Py_UNUSED(ignored))
goto fail;
}
_Py_uop_sym_set_const(ctx, sym, val_42);
TEST_PREDICATE(_Py_uop_sym_is_skip_refcount(ctx, sym), "42 isn't refcounted");
TEST_PREDICATE(_Py_uop_sym_is_strong_ref_held_by_someone_else(ctx, sym), "42 isn't refcounted");
TEST_PREDICATE(_Py_uop_sym_truthiness(ctx, sym) == 1, "bool(42) is not True");
TEST_PREDICATE(!_Py_uop_sym_is_null(sym), "42 is NULL");
TEST_PREDICATE(_Py_uop_sym_is_not_null(sym), "42 isn't not NULL");
Expand Down Expand Up @@ -876,12 +877,12 @@ _Py_uop_symbols_test(PyObject *Py_UNUSED(self), PyObject *Py_UNUSED(ignored))
if (sym == NULL) {
goto fail;
}
TEST_PREDICATE(!_Py_uop_sym_is_skip_refcount(ctx, sym), "type should be refcounted");
_Py_uop_sym_set_skip_refcount(ctx, sym);
TEST_PREDICATE(_Py_uop_sym_is_skip_refcount(ctx, sym), "type should not be refcounted");
TEST_PREDICATE(!_Py_uop_sym_is_strong_ref_held_by_someone_else(ctx, sym), "type should be refcounted");
_Py_uop_sym_set_strong_ref_is_held_by_someone_else(ctx, sym);
TEST_PREDICATE(_Py_uop_sym_is_strong_ref_held_by_someone_else(ctx, sym), "type should not be refcounted");

sym = _Py_uop_sym_new_const(ctx, Py_None);
TEST_PREDICATE(_Py_uop_sym_is_skip_refcount(ctx, sym), "None should not be refcounted");
TEST_PREDICATE(_Py_uop_sym_is_strong_ref_held_by_someone_else(ctx, sym), "None should not be refcounted");
TEST_PREDICATE(_Py_uop_sym_truthiness(ctx, sym) == 0, "bool(None) is not False");
sym = _Py_uop_sym_new_const(ctx, Py_False);
TEST_PREDICATE(_Py_uop_sym_truthiness(ctx, sym) == 0, "bool(False) is not False");
Expand Down
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