gh-115816: Improve internal symbols API in optimizer (#116028)

- Any `sym_set_...` call that attempts to set conflicting information
  cause the symbol to become `bottom` (contradiction).
- All `sym_is...` and similar calls return false or NULL for `bottom`.
- Everything's tested.
- The tests still pass with `PYTHONUOPSOPTIMIZE=1`.
This commit is contained in:
Guido van Rossum 2024-02-28 09:55:56 -08:00 committed by GitHub
parent f58f8cef74
commit e2a3e4b748
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GPG Key ID: B5690EEEBB952194
4 changed files with 190 additions and 66 deletions

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@ -27,12 +27,12 @@ extern PyTypeObject _PyUOpExecutor_Type;
extern PyTypeObject _PyUOpOptimizer_Type;
/* Symbols */
/* See explanation in optimizer_symbols.c */
struct _Py_UopsSymbol {
int flags;
PyTypeObject *typ;
// constant propagated value (might be NULL)
PyObject *const_val;
int flags; // 0 bits: Top; 2 or more bits: Bottom
PyTypeObject *typ; // Borrowed reference
PyObject *const_val; // Owned reference (!)
};
// Holds locals, stack, locals, stack ... co_consts (in that order)
@ -92,7 +92,9 @@ extern _Py_UopsSymbol *_Py_uop_sym_new_const(_Py_UOpsContext *ctx, PyObject *con
extern _Py_UopsSymbol *_Py_uop_sym_new_null(_Py_UOpsContext *ctx);
extern bool _Py_uop_sym_matches_type(_Py_UopsSymbol *sym, PyTypeObject *typ);
extern void _Py_uop_sym_set_null(_Py_UopsSymbol *sym);
extern void _Py_uop_sym_set_type(_Py_UopsSymbol *sym, PyTypeObject *tp);
extern void _Py_uop_sym_set_non_null(_Py_UopsSymbol *sym);
extern void _Py_uop_sym_set_type(_Py_UopsSymbol *sym, PyTypeObject *typ);
extern void _Py_uop_sym_set_const(_Py_UopsSymbol *sym, PyObject *const_val);
extern int _Py_uop_abstractcontext_init(_Py_UOpsContext *ctx);
extern void _Py_uop_abstractcontext_fini(_Py_UOpsContext *ctx);

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@ -294,7 +294,9 @@ remove_globals(_PyInterpreterFrame *frame, _PyUOpInstruction *buffer,
#define sym_new_null _Py_uop_sym_new_null
#define sym_matches_type _Py_uop_sym_matches_type
#define sym_set_null _Py_uop_sym_set_null
#define sym_set_non_null _Py_uop_sym_set_non_null
#define sym_set_type _Py_uop_sym_set_type
#define sym_set_const _Py_uop_sym_set_const
#define frame_new _Py_uop_frame_new
#define frame_pop _Py_uop_frame_pop

View File

@ -22,7 +22,9 @@ typedef struct _Py_UOpsAbstractFrame _Py_UOpsAbstractFrame;
#define sym_new_null _Py_uop_sym_new_null
#define sym_matches_type _Py_uop_sym_matches_type
#define sym_set_null _Py_uop_sym_set_null
#define sym_set_non_null _Py_uop_sym_set_non_null
#define sym_set_type _Py_uop_sym_set_type
#define sym_set_const _Py_uop_sym_set_const
#define frame_new _Py_uop_frame_new
#define frame_pop _Py_uop_frame_pop

View File

@ -10,11 +10,26 @@
#include <stdint.h>
#include <stddef.h>
/* Symbols
=======
See the diagram at
https://github.com/faster-cpython/ideas/blob/main/3.13/redundancy_eliminator.md
We represent the nodes in the diagram as follows
(the flag bits are only defined in optimizer_symbols.c):
- Top: no flag bits, typ and const_val are NULL.
- NULL: IS_NULL flag set, type and const_val NULL.
- Not NULL: NOT_NULL flag set, type and const_val NULL.
- None/not None: not used. (None could be represented as any other constant.)
- Known type: NOT_NULL flag set and typ set; const_val is NULL.
- Known constant: NOT_NULL flag set, type set, const_val set.
- Bottom: IS_NULL and NOT_NULL flags set, type and const_val NULL.
*/
// Flags for below.
#define KNOWN 1 << 0
#define TRUE_CONST 1 << 1
#define IS_NULL 1 << 2
#define NOT_NULL 1 << 3
#define IS_NULL 1 << 0
#define NOT_NULL 1 << 1
#ifdef Py_DEBUG
static inline int get_lltrace(void) {
@ -31,9 +46,8 @@ static inline int get_lltrace(void) {
#define DPRINTF(level, ...)
#endif
// Takes a borrowed reference to const_val, turns that into a strong reference.
static _Py_UopsSymbol *
sym_new(_Py_UOpsContext *ctx, PyObject *const_val)
sym_new(_Py_UOpsContext *ctx)
{
_Py_UopsSymbol *self = &ctx->t_arena.arena[ctx->t_arena.ty_curr_number];
if (ctx->t_arena.ty_curr_number >= ctx->t_arena.ty_max_number) {
@ -42,13 +56,9 @@ sym_new(_Py_UOpsContext *ctx, PyObject *const_val)
return NULL;
}
ctx->t_arena.ty_curr_number++;
self->const_val = NULL;
self->typ = NULL;
self->flags = 0;
if (const_val != NULL) {
self->const_val = Py_NewRef(const_val);
}
self->typ = NULL;
self->const_val = NULL;
return self;
}
@ -59,59 +69,111 @@ sym_set_flag(_Py_UopsSymbol *sym, int flag)
sym->flags |= flag;
}
static inline bool
sym_has_flag(_Py_UopsSymbol *sym, int flag)
static inline void
sym_set_bottom(_Py_UopsSymbol *sym)
{
return (sym->flags & flag) != 0;
sym_set_flag(sym, IS_NULL | NOT_NULL);
sym->typ = NULL;
Py_CLEAR(sym->const_val);
}
static inline bool
_Py_uop_sym_is_bottom(_Py_UopsSymbol *sym)
{
if ((sym->flags & IS_NULL) && (sym->flags & NOT_NULL)) {
assert(sym->flags == (IS_NULL | NOT_NULL));
assert(sym->typ == NULL);
assert(sym->const_val == NULL);
return true;
}
return false;
}
bool
_Py_uop_sym_is_not_null(_Py_UopsSymbol *sym)
{
return (sym->flags & (IS_NULL | NOT_NULL)) == NOT_NULL;
return sym->flags == NOT_NULL;
}
bool
_Py_uop_sym_is_null(_Py_UopsSymbol *sym)
{
return (sym->flags & (IS_NULL | NOT_NULL)) == IS_NULL;
return sym->flags == IS_NULL;
}
bool
_Py_uop_sym_is_const(_Py_UopsSymbol *sym)
{
return (sym->flags & TRUE_CONST) != 0;
return sym->const_val != NULL;
}
PyObject *
_Py_uop_sym_get_const(_Py_UopsSymbol *sym)
{
assert(_Py_uop_sym_is_const(sym));
assert(sym->const_val);
return sym->const_val;
}
void
_Py_uop_sym_set_type(_Py_UopsSymbol *sym, PyTypeObject *tp)
_Py_uop_sym_set_type(_Py_UopsSymbol *sym, PyTypeObject *typ)
{
assert(PyType_Check(tp));
sym->typ = tp;
sym_set_flag(sym, KNOWN);
assert(typ != NULL && PyType_Check(typ));
if (sym->flags & IS_NULL) {
sym_set_bottom(sym);
return;
}
if (sym->typ != NULL) {
if (sym->typ != typ) {
sym_set_bottom(sym);
}
return;
}
sym_set_flag(sym, NOT_NULL);
sym->typ = typ;
}
void
_Py_uop_sym_set_const(_Py_UopsSymbol *sym, PyObject *const_val)
{
assert(const_val != NULL);
if (sym->flags & IS_NULL) {
sym_set_bottom(sym);
return;
}
PyTypeObject *typ = Py_TYPE(const_val);
if (sym->typ != NULL && sym->typ != typ) {
sym_set_bottom(sym);
return;
}
if (sym->const_val != NULL) {
if (sym->const_val != const_val) {
// TODO: What if they're equal?
sym_set_bottom(sym);
}
return;
}
sym_set_flag(sym, NOT_NULL);
sym->typ = typ;
sym->const_val = Py_NewRef(const_val);
}
void
_Py_uop_sym_set_null(_Py_UopsSymbol *sym)
{
sym_set_flag(sym, IS_NULL);
sym_set_flag(sym, KNOWN);
}
void
_Py_uop_sym_set_non_null(_Py_UopsSymbol *sym)
{
sym_set_flag(sym, NOT_NULL);
}
_Py_UopsSymbol *
_Py_uop_sym_new_unknown(_Py_UOpsContext *ctx)
{
return sym_new(ctx, NULL);
return sym_new(ctx);
}
_Py_UopsSymbol *
@ -121,16 +183,14 @@ _Py_uop_sym_new_not_null(_Py_UOpsContext *ctx)
if (res == NULL) {
return NULL;
}
sym_set_flag(res, KNOWN);
sym_set_flag(res, NOT_NULL);
return res;
}
_Py_UopsSymbol *
_Py_uop_sym_new_type(_Py_UOpsContext *ctx,
PyTypeObject *typ)
_Py_uop_sym_new_type(_Py_UOpsContext *ctx, PyTypeObject *typ)
{
_Py_UopsSymbol *res = sym_new(ctx,NULL);
_Py_UopsSymbol *res = sym_new(ctx);
if (res == NULL) {
return NULL;
}
@ -138,20 +198,17 @@ _Py_uop_sym_new_type(_Py_UOpsContext *ctx,
return res;
}
// Takes a borrowed reference to const_val.
// Adds a new reference to const_val, owned by the symbol.
_Py_UopsSymbol *
_Py_uop_sym_new_const(_Py_UOpsContext *ctx, PyObject *const_val)
{
assert(const_val != NULL);
_Py_UopsSymbol *temp = sym_new(ctx, const_val);
if (temp == NULL) {
_Py_UopsSymbol *res = sym_new(ctx);
if (res == NULL) {
return NULL;
}
_Py_uop_sym_set_type(temp, Py_TYPE(const_val));
sym_set_flag(temp, TRUE_CONST);
sym_set_flag(temp, KNOWN);
sym_set_flag(temp, NOT_NULL);
return temp;
_Py_uop_sym_set_const(res, const_val);
return res;
}
_Py_UopsSymbol *
@ -168,8 +225,8 @@ _Py_uop_sym_new_null(_Py_UOpsContext *ctx)
bool
_Py_uop_sym_matches_type(_Py_UopsSymbol *sym, PyTypeObject *typ)
{
assert(typ == NULL || PyType_Check(typ));
if (!sym_has_flag(sym, KNOWN)) {
assert(typ != NULL && PyType_Check(typ));
if (_Py_uop_sym_is_bottom(sym)) {
return false;
}
return sym->typ == typ;
@ -277,15 +334,14 @@ do { \
} \
} while (0)
/*
static _Py_UopsSymbol *
make_contradiction(_Py_UOpsContext *ctx)
make_bottom(_Py_UOpsContext *ctx)
{
_Py_UopsSymbol *sym = _Py_uop_sym_new_unknown(ctx);
_Py_uop_sym_set_null(sym);
_Py_uop_sym_set_type(sym, &PyLong_Type);
_Py_uop_sym_set_non_null(sym);
return sym;
}*/
}
PyObject *
_Py_uop_symbols_test(PyObject *Py_UNUSED(self), PyObject *Py_UNUSED(ignored))
@ -293,31 +349,93 @@ _Py_uop_symbols_test(PyObject *Py_UNUSED(self), PyObject *Py_UNUSED(ignored))
_Py_UOpsContext context;
_Py_UOpsContext *ctx = &context;
_Py_uop_abstractcontext_init(ctx);
PyObject *val_42 = NULL;
PyObject *val_43 = NULL;
_Py_UopsSymbol *top = _Py_uop_sym_new_unknown(ctx);
if (top == NULL) {
return NULL;
// Use a single 'sym' variable so copy-pasting tests is easier.
_Py_UopsSymbol *sym = _Py_uop_sym_new_unknown(ctx);
if (sym == NULL) {
goto fail;
}
TEST_PREDICATE(!_Py_uop_sym_is_null(top), "unknown is NULL");
TEST_PREDICATE(!_Py_uop_sym_is_not_null(top), "unknown is not NULL");
TEST_PREDICATE(!_Py_uop_sym_is_const(top), "unknown is a constant");
// TEST_PREDICATE(_Py_uop_sym_get_const(top) == NULL, "unknown as constant is not NULL");
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");
TEST_PREDICATE(!_Py_uop_sym_is_const(sym), "top is a constant");
TEST_PREDICATE(_Py_uop_sym_get_const(sym) == NULL, "top as constant is not NULL");
TEST_PREDICATE(!_Py_uop_sym_is_bottom(sym), "top is bottom");
// _Py_UopsSymbol *contradiction = make_contradiction(ctx);
// TEST_PREDICATE(_Py_uop_sym_is_null(contradiction), "contradiction is NULL is not true");
// TEST_PREDICATE(_Py_uop_sym_is_not_null(contradiction), "contradiction is not NULL is not true");
// TEST_PREDICATE(_Py_uop_sym_is_const(contradiction), "contradiction is a constant is not true");
sym = make_bottom(ctx);
if (sym == NULL) {
goto fail;
}
TEST_PREDICATE(!_Py_uop_sym_is_null(sym), "bottom is NULL is not false");
TEST_PREDICATE(!_Py_uop_sym_is_not_null(sym), "bottom is not NULL is not false");
TEST_PREDICATE(!_Py_uop_sym_matches_type(sym, &PyLong_Type), "bottom matches a type");
TEST_PREDICATE(!_Py_uop_sym_is_const(sym), "bottom is a constant is not false");
TEST_PREDICATE(_Py_uop_sym_get_const(sym) == NULL, "bottom as constant is not NULL");
TEST_PREDICATE(_Py_uop_sym_is_bottom(sym), "bottom isn't bottom");
_Py_UopsSymbol *int_type = _Py_uop_sym_new_type(ctx, &PyLong_Type);
TEST_PREDICATE(_Py_uop_sym_matches_type(int_type, &PyLong_Type), "inconsistent type");
_Py_uop_sym_set_type(int_type, &PyLong_Type);
TEST_PREDICATE(_Py_uop_sym_matches_type(int_type, &PyLong_Type), "inconsistent type");
_Py_uop_sym_set_type(int_type, &PyFloat_Type);
// TEST_PREDICATE(_Py_uop_sym_matches_type(int_type, &PyLong_Type), "(int and float) doesn't match int");
sym = _Py_uop_sym_new_type(ctx, &PyLong_Type);
if (sym == NULL) {
goto fail;
}
TEST_PREDICATE(!_Py_uop_sym_is_null(sym), "int is NULL");
TEST_PREDICATE(_Py_uop_sym_is_not_null(sym), "int isn't not NULL");
TEST_PREDICATE(_Py_uop_sym_matches_type(sym, &PyLong_Type), "int isn't int");
TEST_PREDICATE(!_Py_uop_sym_matches_type(sym, &PyFloat_Type), "int matches float");
TEST_PREDICATE(!_Py_uop_sym_is_const(sym), "int is a constant");
TEST_PREDICATE(_Py_uop_sym_get_const(sym) == NULL, "int as constant is not NULL");
_Py_uop_sym_set_type(sym, &PyLong_Type); // Should be a no-op
TEST_PREDICATE(_Py_uop_sym_matches_type(sym, &PyLong_Type), "(int and int) isn't int");
_Py_uop_sym_set_type(sym, &PyFloat_Type); // Should make it bottom
TEST_PREDICATE(_Py_uop_sym_is_bottom(sym), "(int and float) isn't bottom");
val_42 = PyLong_FromLong(42);
assert(val_42 != NULL);
assert(_Py_IsImmortal(val_42));
val_43 = PyLong_FromLong(43);
assert(val_43 != NULL);
assert(_Py_IsImmortal(val_43));
sym = _Py_uop_sym_new_type(ctx, &PyLong_Type);
if (sym == NULL) {
goto fail;
}
_Py_uop_sym_set_const(sym, val_42);
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");
TEST_PREDICATE(_Py_uop_sym_matches_type(sym, &PyLong_Type), "42 isn't an int");
TEST_PREDICATE(!_Py_uop_sym_matches_type(sym, &PyFloat_Type), "42 matches float");
TEST_PREDICATE(_Py_uop_sym_is_const(sym), "42 is not a constant");
TEST_PREDICATE(_Py_uop_sym_get_const(sym) != NULL, "42 as constant is NULL");
TEST_PREDICATE(_Py_uop_sym_get_const(sym) == val_42, "42 as constant isn't 42");
_Py_uop_sym_set_type(sym, &PyLong_Type); // Should be a no-op
TEST_PREDICATE(_Py_uop_sym_matches_type(sym, &PyLong_Type), "(42 and 42) isn't an int");
TEST_PREDICATE(_Py_uop_sym_get_const(sym) == val_42, "(42 and 42) as constant isn't 42");
_Py_uop_sym_set_type(sym, &PyFloat_Type); // Should make it bottom
TEST_PREDICATE(_Py_uop_sym_is_bottom(sym), "(42 and float) isn't bottom");
sym = _Py_uop_sym_new_type(ctx, &PyLong_Type);
if (sym == NULL) {
goto fail;
}
_Py_uop_sym_set_const(sym, val_42);
_Py_uop_sym_set_const(sym, val_43); // Should make it bottom
TEST_PREDICATE(_Py_uop_sym_is_bottom(sym), "(42 and 43) isn't bottom");
_Py_uop_abstractcontext_fini(ctx);
Py_DECREF(val_42);
Py_DECREF(val_43);
Py_RETURN_NONE;
fail:
_Py_uop_abstractcontext_fini(ctx);
Py_XDECREF(val_42);
Py_XDECREF(val_43);
return NULL;
}