pytorch/torch/_inductor/codegen/mps.py
Nikita Shulga ec816d73b4 [MPS] Add shifted_chebyshev_polynomial_[tuvw] (#157488)
For eager and inductor

As for all other chebyshev ops, logic is simply compiled from 94716db222/aten/src/ATen/native/cuda/Math.cuh (L2821)

Pull Request resolved: https://github.com/pytorch/pytorch/pull/157488
Approved by: https://github.com/dcci
2025-07-03 15:48:37 +00:00

996 lines
37 KiB
Python

# This is not a feature-complete compiler backend
# Just an early prototype that shows that one can compile elementwise ops into a Metal shader
from __future__ import annotations
import functools
import itertools
import logging
import math
from pathlib import Path
from typing import Any, Optional, TYPE_CHECKING
import sympy
from sympy.printing.precedence import PRECEDENCE
import torch
from torch.utils._cpp_embed_headers import _embed_headers
from torch.utils._ordered_set import OrderedSet
from torch.utils._sympy.printers import CppPrinter, ExprPrinter as ExprPrinter_
from torch.utils._sympy.value_ranges import ValueRanges
from ..utils import ceildiv, get_bounds_index_expr, get_kernel_metadata
from ..virtualized import ops, OpsWrapper, V
from .common import (
CSEVariable,
DeferredLine,
DTYPE_TO_COMPUTATION_DTYPE,
IndentedBuffer,
OpOverrides,
PythonPrinter,
)
from .simd import IterationRangesEntry, SIMDKernel, SIMDScheduling
if TYPE_CHECKING:
from typing import Union
from ..ops_handler import ReductionType, StoreMode
from ..scheduler import Scheduler, SchedulerNode
from .common import OpVarT
log = logging.getLogger(__name__)
DTYPE_TO_METAL = {
torch.bool: "bool",
torch.int8: "char",
torch.int16: "short",
torch.int32: "int",
torch.int64: "long",
torch.uint8: "uchar",
torch.float: "float",
torch.half: "half",
torch.bfloat16: "bfloat",
}
def value_to_metal(val: Union[float, int, bool, str, CSEVariable]) -> str:
if isinstance(val, float):
if val == torch.inf:
return "HUGE_VALF"
elif val == -torch.inf:
return "-HUGE_VALF"
elif val != val: # Only float that not equal to self is nan
return "NAN"
return str(val)
elif isinstance(val, bool):
return "true" if val else "false"
return str(val)
class MetalExprPrinter(ExprPrinter_):
"""Converts sympy expression to Metal code snippet"""
def _print_FloorDiv(self, expr: sympy.Expr) -> str:
x, div = expr.args
x = self.doprint(x)
div = self.doprint(div)
if expr.is_integer:
return f"c10::metal::floor_divide({x}, {div})"
return f"metal::floor({x}) / ({div})"
def _print_ModularIndexing(self, expr: sympy.Expr) -> str:
x, div, mod = expr.args
x = self.doprint(x)
if div != 1:
div = self.doprint(div)
if expr.is_integer:
x = f"({x}) / ({div})"
else:
x = f"metal::floor({x}) / ({div})"
mod = self.doprint(mod)
return f"({x}) % ({mod})"
def _print_Min(self, expr: sympy.Expr) -> str:
if len(expr.args) != 2:
raise RuntimeError("metal::min only supported for 2 args")
a, b = map(self._print, expr.args)
typecast_a = f"static_cast<decltype({a}+{b})>({a})"
typecast_b = f"static_cast<decltype({a}+{b})>({b})"
return f"metal::min({typecast_a}, {typecast_b})"
def _print_Max(self, expr: sympy.Expr) -> str:
if len(expr.args) != 2:
raise RuntimeError("metal::max only supported for 2 args")
a, b = map(self._print, expr.args)
typecast_a = f"static_cast<decltype({a}+{b})>({a})"
typecast_b = f"static_cast<decltype({a}+{b})>({b})"
return f"metal::max({typecast_a}, {typecast_b})"
def _print_Abs(self, expr: sympy.Expr) -> str:
assert len(expr.args) == 1
return f"metal::abs({self._print(expr.args[0])})"
def _print_RoundToInt(self, expr: sympy.Expr) -> str:
assert len(expr.args) == 1
return f"static_cast<long>(metal::rint({self._print(expr.args[0])}))"
def _print_RoundDecimal(self, expr: sympy.Expr) -> str:
assert len(expr.args) == 2
number, ndigits = expr.args
if number.is_integer:
# ndigits < 0 should have been filtered by the sympy function
assert ndigits < 0
raise ValueError(
f"For integer inputs, only non-negative ndigits are currently supported, but got {ndigits}."
)
number_str = self.parenthesize(number, PRECEDENCE["Mul"])
return f"static_cast<float>(metal::rint(1e{ndigits} * {number_str}) * 1e{-ndigits})"
def _print_IntTrueDiv(self, expr: sympy.Expr) -> str:
lhs, rhs = expr.args
# TODO: This is only accurate up to 2**23
return f"static_cast<float>({self._print(lhs)}) / static_cast<float>({self._print(rhs)})"
def _print_PowByNatural(self, expr: sympy.Expr) -> str:
assert len(expr.args) == 2
x, y = map(self.doprint, expr.args)
return f"metal::pow(static_cast<float>({x}), static_cast<float>({y}))"
def _print_ToFloat(self, expr: sympy.Expr) -> str:
assert len(expr.args) == 1
x = self.doprint(expr.args[0])
return f"static_cast<float>({x})"
def _print_FloorToInt(self, expr: sympy.Expr) -> str:
assert len(expr.args) == 1
x = self.doprint(expr.args[0])
return f"static_cast<int>(metal::floor(static_cast<float>({x})))"
_print_floor = _print_FloorToInt
def _print_TruncToInt(self, expr: sympy.Expr) -> str:
assert len(expr.args) == 1
x = self.doprint(expr.args[0])
return f"static_cast<int>(metal::trunc({x}))"
def _print_OpaqueUnaryFn_log2(self, expr: sympy.Expr) -> str:
assert len(expr.args) == 1
x = self.doprint(expr.args[0])
return f"metal::log2({x})"
class MetalOverrides(OpOverrides):
"""Implements Metal-specific overrides for ops. Base class emits Python-friendly overrides."""
@staticmethod
def to_dtype(
x: CSEVariable,
dtype: torch.dtype,
src_dtype: Optional[torch.dtype] = None,
use_compute_types: bool = True,
) -> str:
if dtype == torch.double:
log.warning(
"float64 cast requested, probably from tensorify_python_scalars"
)
return f"static_cast<float>({x})"
return f"static_cast<{DTYPE_TO_METAL[dtype]}>({x})"
@staticmethod
def to_dtype_bitcast(
x: CSEVariable, dtype: torch.dtype, src_dtype: torch.dtype
) -> str:
return f"as_type<{DTYPE_TO_METAL[dtype]}>(static_cast<{DTYPE_TO_METAL[src_dtype]}>({x}))"
@staticmethod
def constant(val: Union[bool, float, int], dtype: torch.dtype) -> str:
return value_to_metal(val)
@staticmethod
def index_expr(expr: sympy.Expr, dtype: torch.dtype) -> str:
idx_str = V.kernel.index_to_str(V.kernel.prepare_indexing(expr))
var = V.kernel.cse.generate(
V.kernel.compute, idx_str, bounds=get_bounds_index_expr(expr)
)
return ops.to_dtype(var, dtype)
@staticmethod
def masked(mask: CSEVariable, body: sympy.Expr, other: CSEVariable) -> str:
# TODO: Type annotation for other is wrong, it's often float or int
with V.kernel.mask_loads(mask, other) as new_mask:
result = body()
if result.bounds.is_bool:
other = bool(other) # type: ignore[assignment]
return ops.where(new_mask, result, other)
@staticmethod
def where(a: OpVarT, b: OpVarT, c: OpVarT) -> str:
return f"{a} ? {b} : {value_to_metal(c)}"
@staticmethod
def remainder(a: OpVarT, b: OpVarT) -> str:
return f"c10::metal::remainder({a}, {b})"
@staticmethod
def maximum(a: CSEVariable, b: CSEVariable) -> str:
typecast_a = f"static_cast<decltype({a}+{b})>({a})"
typecast_b = f"static_cast<decltype({a}+{b})>({b})"
return f"c10::metal::max({typecast_a}, {typecast_b})"
@staticmethod
def minimum(a: CSEVariable, b: CSEVariable) -> str:
typecast_a = f"static_cast<decltype({a}+{b})>({a})"
typecast_b = f"static_cast<decltype({a}+{b})>({b})"
return f"c10::metal::min({typecast_a}, {typecast_b})"
@staticmethod
def logical_or(a: CSEVariable, b: CSEVariable) -> str:
return f"{a} || {b}"
@staticmethod
def logical_and(a: CSEVariable, b: CSEVariable) -> str:
return f"{a} && {b}"
@staticmethod
def isnan(x: CSEVariable) -> str:
return f"metal::isnan({x})"
@staticmethod
def isinf(x: CSEVariable) -> str:
return f"metal::isinf({x})"
@staticmethod
def log(x: CSEVariable) -> str:
return f"metal::log({x})"
@staticmethod
def exp(x: CSEVariable) -> str:
return f"metal::exp({x})"
@staticmethod
def abs(x: CSEVariable) -> str:
return f"metal::abs({x})"
@staticmethod
def signbit(x: CSEVariable) -> str:
return f"metal::signbit({x})"
@staticmethod
def sin(x: CSEVariable) -> str:
return f"metal::precise::sin({x})"
@staticmethod
def sinc(x: CSEVariable) -> str:
return f"c10::metal::sinc({x})"
@staticmethod
def cos(x: CSEVariable) -> str:
return f"metal::precise::cos({x})"
@staticmethod
def tan(x: CSEVariable) -> str:
return f"metal::tan({x})"
@staticmethod
def asin(x: CSEVariable) -> str:
return f"metal::asin({x})"
@staticmethod
def acos(x: CSEVariable) -> str:
return f"metal::acos({x})"
@staticmethod
def atan(x: CSEVariable) -> str:
return f"metal::atan({x})"
@staticmethod
def atan2(x: CSEVariable, y: CSEVariable) -> str:
return f"::metal::atan2({x}, {y})"
@staticmethod
def sqrt(x: CSEVariable) -> str:
return f"metal::sqrt({x})"
@staticmethod
def neg(x: CSEVariable) -> str:
# TODO: Does it rely on undefined behavior?
# If so, add special logic for unsigned types
return f"static_cast<decltype({x})>(-{x})"
@staticmethod
def rsqrt(x: CSEVariable) -> str:
return f"metal::rsqrt({x})"
@staticmethod
def tanh(x: CSEVariable) -> str:
return f"metal::tanh({x})"
@staticmethod
def atanh(x: CSEVariable) -> str:
return f"metal::atanh({x})"
@staticmethod
def floordiv(a: CSEVariable, b: CSEVariable) -> str:
# a and b must be of integer type
return f"c10::metal::floor_divide({a}, {b})"
@staticmethod
def floor(x: CSEVariable) -> str:
return f"metal::floor({x})"
@staticmethod
def sign(x: CSEVariable) -> str:
return f"metal::sign({x})"
@staticmethod
def fmod(a: CSEVariable, b: CSEVariable) -> str:
typecast_a = f"static_cast<decltype({a}+{b})>({a})"
typecast_b = f"static_cast<decltype({a}+{b})>({b})"
return f"metal::fmod({typecast_a}, {typecast_b})"
@staticmethod
def trunc(x: CSEVariable) -> str:
return f"metal::trunc({x})"
@staticmethod
def truncdiv(a: CSEVariable, b: CSEVariable) -> str:
quot = f"{a} / {b}"
if (a.dtype is not None and a.dtype.is_floating_point) or (
b.dtype is not None and b.dtype.is_floating_point
):
return f"metal::trunc({quot})"
return quot
@staticmethod
def ceil(x: CSEVariable) -> str:
return f"metal::ceil({x})"
@staticmethod
def rand(seed: CSEVariable, offset: CSEVariable) -> str:
V.kernel.headers.add("random")
return f"c10::metal::rand({seed}, {offset})"
@staticmethod
def randn(seed: CSEVariable, offset: CSEVariable) -> str:
V.kernel.headers.add("random")
return f"c10::metal::randn({seed}, {offset})"
@staticmethod
def randint64(
seed: CSEVariable, offset: CSEVariable, low: CSEVariable, high: CSEVariable
) -> str:
V.kernel.headers.add("random")
return f"c10::metal::randint64({seed}, {offset}, {low}, {high})"
@staticmethod
def round(x: CSEVariable) -> str:
return f"metal::round({x})"
@staticmethod
def pow(a: CSEVariable, b: CSEVariable) -> str:
cast_a = f"static_cast<decltype({a}+{b})>({a})"
cast_b = f"static_cast<decltype({a}+{b})>({b})"
return f"metal::pow({cast_a}, {cast_b})"
def _special_unary(self, a: CSEVariable, name: str) -> str:
V.kernel.headers.add("special_math")
return f"c10::metal::{name}({a})"
def _special_binary(self, a: CSEVariable, b: CSEVariable, name: str) -> str:
V.kernel.headers.add("special_math")
return f"c10::metal::{name}({a}, {b})"
@classmethod
def _initialize_special_ops(cls) -> None:
# Unary special ops
for name in [
"erf",
"erfinv",
"i0",
"i0e",
"i1",
"i1e",
"digamma",
"spherical_bessel_j0",
]:
setattr(cls, name, functools.partialmethod(cls._special_unary, name=name))
cls.lgamma = functools.partialmethod(cls._special_unary, name="log_gamma") # type: ignore[assignment]
# Unary special ops with forward in method name
for name in [
"bessel_j0",
"bessel_j1",
"bessel_y0",
"bessel_y1",
"modified_bessel_i0",
"modified_bessel_i1",
"modified_bessel_k0",
"modified_bessel_k1",
"scaled_modified_bessel_k0",
"scaled_modified_bessel_k1",
]:
setattr(
cls,
name,
functools.partialmethod(cls._special_unary, name=name + "_forward"),
)
# Binary special ops
for name in [
"polygamma",
"zeta",
]:
setattr(cls, name, functools.partialmethod(cls._special_binary, name=name))
# Binary special ops with forward in method name
for name in [
"chebyshev_polynomial_t",
"chebyshev_polynomial_u",
"chebyshev_polynomial_v",
"chebyshev_polynomial_w",
"hermite_polynomial_h",
"hermite_polynomial_he",
"shifted_chebyshev_polynomial_t",
"shifted_chebyshev_polynomial_u",
"shifted_chebyshev_polynomial_v",
"shifted_chebyshev_polynomial_w",
]:
setattr(
cls,
name,
functools.partialmethod(cls._special_binary, name=name + "_forward"),
)
MetalOverrides._initialize_pointwise_overrides("mps")
MetalOverrides._initialize_special_ops()
class MetalKernel(SIMDKernel):
"""Implement Metal codegen based on the SIMDKernel abstraction"""
overrides = MetalOverrides # type: ignore[assignment]
suffix = ";"
newvar_prefix = "auto "
max_threadgroup_size = 1024
simd_group_size = 32
pexpr = PythonPrinter().doprint
cexpr = CppPrinter().doprint
sexpr = MetalExprPrinter().doprint
kexpr = sexpr
headers: OrderedSet[str] = OrderedSet(["utils"])
multistage_reduction_entry: list[IterationRangesEntry] = []
def __init__(
self,
tiling: dict[str, sympy.Expr],
**kwargs: Any,
) -> None:
super().__init__(tiling, **kwargs)
self.acc_var_ids = itertools.count()
def dtype_to_str(self, dtype: torch.dtype) -> str:
return DTYPE_TO_METAL[dtype]
def load(self, name: str, index: sympy.Expr) -> CSEVariable:
"""Codegen a load from an InputBuffer"""
var = self.args.input(name)
index = self.prepare_indexing(index)
dtype = V.graph.get_dtype(name)
line = f"{var}[{self.index_to_str(index)}]"
if dtype in [torch.float16, torch.bfloat16]:
# TODO(NS): Figure out the right balance between optype casts
# op_math_t for half-precision floats should be float32
# Otherwise it can lead to a correctness issues with eager
line = f"static_cast<float>({line})"
dtype = torch.float32
return self.cse.generate(self.loads, line, dtype=dtype)
def store(
self, name: str, index: sympy.Expr, value: CSEVariable, mode: StoreMode = None
) -> None:
var = self.args.output(name)
index = self.prepare_indexing(index)
dtype_str = self.dtype_to_str(V.graph.get_dtype(name))
cast_val = f"static_cast<{dtype_str}>({value})"
if mode is None:
line = f"{var}[{self.index_to_str(index)}] = {cast_val};"
elif mode == "atomic_add":
self.headers.add("atomic")
atomic_type = f"c10::metal::AtomicType<{dtype_str}>"
cast_var = f"reinterpret_cast<device {atomic_type}::type *>({var})"
line = f"{atomic_type}::atomic_add({cast_var}, {self.index_to_str(index)}, {cast_val});"
else:
raise RuntimeError(f"Unimplemented store mode {mode}")
if self.inside_reduction:
self.compute.writeline(DeferredLine(name, line))
else:
self.stores.writeline(DeferredLine(name, line))
def store_reduction(self, name: str, index: sympy.Expr, value: CSEVariable) -> None:
var = self.args.output(name)
index = self.prepare_indexing(index)
dtype_str = self.dtype_to_str(V.graph.get_dtype(name))
reduction_dim = next(t for t in self.range_trees if t.is_reduction)
# Only one thread in the reduction group needs to store the results
line = f"{var}[{self.index_to_str(index)}] = static_cast<{dtype_str}>({value});"
line = f"if ({reduction_dim.name} == 0) {line}"
self.stores.writeline(DeferredLine(name, line))
def _new_idxvar(
self,
dtype: Union[str | torch.dtype],
elem_count: Optional[int] = None,
default_value: Optional[Any] = None,
is_threadgroup: bool = True,
bounds: ValueRanges[Any] = ValueRanges.unknown(),
) -> CSEVariable:
if isinstance(dtype, torch.dtype):
dtype = self.dtype_to_str(dtype)
var_name = f"tmp_acc_{next(self.acc_var_ids)}"
var = V.kernel.create_cse_var(var_name, bounds, dtype)
var_def = "threadgroup " if is_threadgroup else ""
var_def += f"{dtype} {var_name}"
if elem_count:
var_def += f"[{elem_count}]"
if default_value is not None:
assert not is_threadgroup, "Thread group var can not have default value"
var_def += f" = {default_value}"
self.indexing_code.writeline(var_def + self.suffix)
return var
def reduction(
self,
dtype: torch.dtype,
src_dtype: torch.dtype,
reduction_type: ReductionType,
value: Union[CSEVariable, tuple[CSEVariable, ...]],
) -> Union[CSEVariable, tuple[CSEVariable, ...]]:
"Caching wrapper around _reduction_nocache"
cache_key = (src_dtype, reduction_type, value)
# Return cached reduction
if cache_key in self.cse.reduction_cache:
return self.cse.reduction_cache[cache_key]
result = self._reduction_nocache(dtype, src_dtype, reduction_type, value)
self.cse.reduction_cache[cache_key] = result # type: ignore[assignment]
return result
def _reduction_nocache(
self,
dtype: torch.dtype,
src_dtype: torch.dtype,
reduction_type: ReductionType,
value: Union[CSEVariable, tuple[CSEVariable, ...]],
) -> Union[CSEVariable, tuple[CSEVariable, ...]]:
"""Codegen a reduction operation.
Only sum and prod operations are somewhat reasonable optimized"""
assert self.inside_reduction
assert not self._load_mask
def _unwrap_helper(res3: CSEVariable) -> tuple[CSEVariable, ...]:
# Uwraps vec3 dtype into individual components
return OpsWrapper._unwrap(
[CSEVariable(f"{res3}.{t}", res3.bounds, res3.dtype) for t in "xyz"]
)
# Establish reduction buffer size and index expression
reduction_idx = ""
acc_buf_size = 1
for rd in self.range_trees:
if not rd.is_reduction:
continue
if reduction_idx:
reduction_idx += " + "
reduction_idx += f"{rd.name} * {acc_buf_size}"
acc_buf_size *= rd.numel
acc_buf_size = min(acc_buf_size, self.max_threadgroup_size)
if reduction_type == "any":
acc = self._new_idxvar(dtype)
self.indexing_code.writeline(f"{acc} = false;")
self.indexing_code.writeline(
"threadgroup_barrier(metal::mem_flags::mem_threadgroup);"
)
self.compute.splice(
f"""
if ({value}) {{
{acc} = true;
}}
"""
)
self.stores.writeline(
"threadgroup_barrier(metal::mem_flags::mem_threadgroup);"
)
return acc
self.headers.add("reduction_utils")
if reduction_type in ["prod", "sum"]:
acc_dtype = DTYPE_TO_COMPUTATION_DTYPE[src_dtype]
acc_buf = self._new_idxvar(
acc_dtype, ceildiv(acc_buf_size, self.simd_group_size)
)
if not self.multistage_reduction_entry:
val = value
else:
default_val, reduction_op = (
(0, "+") if reduction_type == "sum" else (1, "*")
)
val = self._new_idxvar(
acc_dtype, default_value=default_val, is_threadgroup=False
)
self.compute.splice(f"{val} {reduction_op}= {value};")
return self.cse.generate(
self.stores,
f"c10::metal::threadgroup_{reduction_type}({acc_buf}, {val}, {reduction_idx}, {acc_buf_size})",
dtype=DTYPE_TO_COMPUTATION_DTYPE[dtype],
)
if reduction_type in ["max", "min", "argmin", "argmax"]:
acc_buf = self._new_idxvar(src_dtype, acc_buf_size)
acc_thread_var = f"{acc_buf}[{reduction_idx}]"
src_metal_type = DTYPE_TO_METAL[src_dtype]
if not self.multistage_reduction_entry:
self.compute.splice(
f"{acc_thread_var} = static_cast<{src_metal_type}>({value});"
)
return self.cse.generate(
self.stores,
f"c10::metal::threadgroup_{reduction_type}({acc_buf}, {acc_buf_size})",
dtype=dtype,
)
lim_fn = "lowest" if reduction_type.endswith("max") else "max"
self.indexing_code.writeline(
f"{acc_thread_var} = ::metal::numeric_limits<{src_metal_type}>::{lim_fn}();"
)
if reduction_type.startswith("arg"):
idx_var = next(
t for t in self.range_tree_nodes.values() if t.is_reduction
)
idx_acc_buf = self._new_idxvar(torch.long, acc_buf_size)
cmp_op = ">" if reduction_type == "argmax" else "<"
idx_thread_var = f"{idx_acc_buf}[{reduction_idx}]"
self.indexing_code.splice(f"{idx_thread_var} = -1;")
self.compute.splice(f"""
if ({value} {cmp_op} {acc_thread_var}) {{
{acc_thread_var} = {value};
{idx_thread_var} = {idx_var.name};
}}
""")
return self.cse.generate(
self.stores,
f"{idx_acc_buf}[c10::metal::threadgroup_{reduction_type}({acc_buf}, {acc_buf_size})]",
dtype=dtype,
)
self.compute.writeline(
f"{acc_thread_var} = ::c10::metal::{reduction_type}({acc_thread_var}, {value});"
)
return self.cse.generate(
self.stores,
f"c10::metal::threadgroup_{reduction_type}({acc_buf}, {acc_buf_size})",
dtype=dtype,
)
if reduction_type == "welford_reduce":
if not self.multistage_reduction_entry:
acc_buf = self._new_idxvar(src_dtype, acc_buf_size)
self.compute.splice(f"{acc_buf}[{reduction_idx}] = {value};")
wf_res = self.cse.generate(
self.compute,
f"c10::metal::threadgroup_{reduction_type}({acc_buf}, {acc_buf_size})",
dtype=torch.float32,
)
return _unwrap_helper(wf_res)
acc_buf = self._new_idxvar("float3", acc_buf_size)
acc_thread_var = f"{acc_buf}[{reduction_idx}]"
self.indexing_code.splice(f"{acc_thread_var} = 0.0;")
self.compute.writeline(
f"{acc_thread_var} = ::c10::metal::welford_combine({acc_thread_var}, float3({value}, 0.0, 1.0));"
)
wf_res = self.cse.generate(
self.stores,
f"c10::metal::threadgroup_welford_combine({acc_buf}, {acc_buf_size})",
dtype=torch.float32,
)
return _unwrap_helper(wf_res)
if reduction_type == "welford_combine":
assert isinstance(value, tuple), "Input to welford combine must be tuple"
acc_buf = self._new_idxvar("float3", acc_buf_size)
acc_thread_var = f"{acc_buf}[{reduction_idx}]"
inp_value = f"float3({value[0]}, {value[1]}, {value[2]})"
self.indexing_code.splice(f"{acc_thread_var} = 0.0;")
if self.multistage_reduction_entry:
self.indexing_code.splice(f"{acc_thread_var} = 0.0;")
self.compute.writeline(
f"{acc_thread_var} = ::c10::metal::welford_combine({acc_thread_var}, {inp_value});"
)
else:
self.compute.writeline(f"{acc_thread_var} = {inp_value};")
wf_res = self.cse.generate(
self.stores if self.multistage_reduction_entry else self.compute,
f"c10::metal::threadgroup_{reduction_type}({acc_buf}, {acc_buf_size})",
dtype=torch.float32,
)
return _unwrap_helper(wf_res)
raise NotImplementedError(reduction_type)
def codegen_iteration_ranges_entry(self, entry: IterationRangesEntry) -> None:
index_expr = self.rename_indexing(entry.expr)
index_str = self.sexpr(index_expr) # type: ignore[misc]
if not entry.is_reduction or entry.root.numel <= self.max_threadgroup_size:
self.indexing_code.writeline(
f"{self.index_dtype} {entry.name} = {index_str};"
)
return
self.multistage_reduction_entry.append(entry)
# When reducing the tensor whose size exceeds max threadgroup size
# loop over extra indices per reduction thread and perform part of the operation
# using values in the shared memory
loop_size = (
entry.root.numel + self.max_threadgroup_size - 1
) // self.max_threadgroup_size
self.body.writeline(
f"for(auto {entry.name}_cnt = 0; {entry.name}_cnt < {loop_size}; ++{entry.name}_cnt) {{"
)
with self.body.indent():
self.body.writeline(
f"{self.index_dtype} {entry.name} = {loop_size} * {index_str} + {entry.name}_cnt;"
)
# Check that reduction is performed only within tensor boundary
if loop_size * self.max_threadgroup_size != entry.root.numel:
self.body.writeline(f"if ({entry.name} >= {entry.root.numel}) break;")
def codegen_body(self) -> None:
"""
Concat output code from index_code, loads, compute, stores,
suffix into self.body.
For pointwise kernels, this is called just once at the end.
For reduction kernels, this generates a loop over the reduction
axis.
"""
if self.multistage_reduction_entry:
with self.body.indent():
self.body.splice(self.loads)
self.body.splice(self.compute)
self.body.writeline("}" * len(self.multistage_reduction_entry))
# Invalidate variables instantiated inside loop
# But results of reduction alive. Reduction cache values can be
# either CSEVariable or tuple of CSEVariables, in which case all
# variables in the tuple must be preserved
self.cse.invalidate(
OrderedSet(
v
for item in self.cse.reduction_cache.values()
for v in (item if isinstance(item, tuple) else (item,))
)
)
# And loop codegen
while self.multistage_reduction_entry:
self.multistage_reduction_entry.pop().cache_clear()
else:
self.body.splice(self.loads)
self.body.splice(self.compute)
self.body.splice(self.stores)
self.loads.clear()
self.compute.clear()
self.stores.clear()
def codegen_kernel(self, name: Optional[str] = None) -> str:
"""Called at the end to generate a final kernel string"""
self.codegen_body()
code = IndentedBuffer()
if V.graph.cpp_wrapper:
code.writeline('(R"MTL(')
else:
code.writeline("compile_mps_shader('''")
idx_vars = self.active_range_trees()
with code.indent():
if not V.graph.cpp_wrapper:
for header in self.headers:
code.writeline(f"#include <c10/metal/{header}.h>")
else:
headers = [
f"#include <c10/metal/{header}.h>" for header in self.headers
]
header_contents = _embed_headers(
headers,
[Path(__file__).parent.parent.parent / "include"],
OrderedSet(), # type: ignore[arg-type]
)
code.writeline(header_contents)
if self.inside_reduction:
total_reduction_size = math.prod(
t.numel for t in self.range_trees if t.is_reduction
)
threadgroup_size = min(total_reduction_size, self.max_threadgroup_size)
code.writeline(
f"[[max_total_threads_per_threadgroup({threadgroup_size})]]"
)
code.writeline("kernel void generated_kernel(")
with code.indent():
for outer, inner in self.args.output_buffers.items():
if outer in self.removed_buffers:
continue
dtype_str = self.dtype_to_str(V.graph.get_dtype(outer))
code.writeline(f"device {dtype_str}* {inner},")
for outer, inner in self.args.input_buffers.items():
dtype = V.graph.get_dtype(outer)
# MPS does not support float64, but scalar inputs are fine
if dtype == torch.float64:
outer_buf = V.graph.try_get_buffer(outer)
if outer_buf is None or outer_buf.get_size() != []:
raise RuntimeError("float64 is not supported by MPS")
dtype_str = "float"
else:
dtype_str = self.dtype_to_str(dtype)
code.writeline(f"constant {dtype_str}* {inner},")
for outer, inner in self.args.sizevars.items():
code.writeline(f"constant long& {inner},")
assert len(idx_vars) < 4, "Up to 3 index variables are supported"
thread_pos_dtype = (
f"uint{len(idx_vars)}" if len(idx_vars) > 1 else "uint"
)
thread_pos_var_name = (
idx_vars[0].name if len(idx_vars) == 1 else "thread_pos"
)
thread_pos_suffix = "," if self.inside_reduction else ""
code.writeline(
f"{thread_pos_dtype} {thread_pos_var_name} [[thread_position_in_grid]]{thread_pos_suffix}"
)
if self.inside_reduction:
code.writeline(
f"{thread_pos_dtype} group_pos [[thread_position_in_threadgroup]]"
)
code.writeline(") {")
with code.indent():
if len(idx_vars) > 1:
for idx, var in enumerate(idx_vars):
code.writeline(
f"auto {var.name} = thread_pos.{chr(120 + idx)};"
)
code.splice(self.indexing_code)
code.splice(self.body)
code.writeline("}")
if V.graph.cpp_wrapper:
code.writeline(')MTL");')
else:
code.writeline("''')")
return code.getvalue()
def call_kernel(self, name: str, node: Any = None) -> None:
"""Codegen a call to this kernel"""
wrapper = V.graph.wrapper_code
# Make sure sizevars has been computed
for v in self.args.sizevars.keys():
wrapper.ensure_size_computed(v)
_, call_args, _, arg_types = self.args.python_argdefs()
arg_name_to_type = {
str(call_arg): arg_type for call_arg, arg_type in zip(call_args, arg_types)
}
args = [*self.args.output_buffers.keys(), *self.args.input_buffers.keys()]
args = [arg for arg in args if arg not in self.removed_buffers]
args += [str(v) for v in self.args.sizevars.keys()]
arg_types = [arg_name_to_type[arg] for arg in args]
expr_printer = self.cexpr if V.graph.cpp_wrapper else self.pexpr
def format_threads(threads: list[str], kwarg: str) -> str:
if V.graph.cpp_wrapper:
threads = [f"static_cast<uint64_t>({t})" for t in threads]
return f"{{{', '.join(threads)}}}"
else:
return f"{kwarg}=[{', '.join(threads)}]"
# For reduction kernels, limit the maximum size over reduction dimensions to
# a maximum threadgroup size
if len(self.active_range_trees()) > 0:
threads = [
expr_printer(
sympy.Min(v.numel, self.max_threadgroup_size) # type: ignore[misc]
if v.is_reduction
else v.numel
)
for v in self.active_range_trees()
]
args.append(format_threads(threads, "threads"))
arg_types.append(list)
else:
if V.graph.cpp_wrapper:
raise RuntimeError("We should always have threads?")
if self.inside_reduction:
threads = [
expr_printer(sympy.Min(v.numel, self.max_threadgroup_size)) # type: ignore[misc]
if v.is_reduction
else "1"
for v in self.active_range_trees()
]
args.append(format_threads(threads, "group_size"))
arg_types.append(list)
else:
if V.graph.cpp_wrapper:
# Add a None so that we always have a group_size in the
# arguments. We won't use it if the value is None.
args += [None] # type: ignore[list-item]
arg_types.append(None)
wrapper.generate_kernel_call(
name,
args,
device=torch.device("cpu"), # TODO: Fix me, MPS does not expose streams now
triton=False,
arg_types=arg_types,
)
def check_bounds(
self, expr: sympy.Expr, size: sympy.Expr, lower: bool, upper: bool
) -> None:
if not (lower or upper):
return
# TODO(malfet): support asserts
# See https://github.com/pytorch/pytorch/issues/144634
expr_str = self.index_to_str(expr)
lower_expr = f"{expr_str} < 0" if lower else ""
# TODO(malfet): Is upper bound inclusive or exclusive?
upper_expr = f"{expr_str} > {self.index_to_str(size)}" if upper else ""
if lower and upper:
line = f"if (({lower_expr}) && ({upper_expr})) return"
else:
line = f"if ({lower_expr}{upper_expr}) return"
self.cse.generate(self.compute, line, assignment=False)
class MetalScheduling(SIMDScheduling):
kernel_type = MetalKernel # type: ignore[assignment]
def __init__(self, scheduler: Optional[Scheduler]) -> None:
super().__init__(scheduler)
wrapper = V.graph.wrapper_code
if wrapper is not None:
if not V.graph.cpp_wrapper:
wrapper.header.splice(
"from torch._inductor.runtime.runtime_utils import compile_mps_shader"
)
def define_kernel(
self, src_code: str, node_schedule: list[SchedulerNode], kernel: MetalKernel
) -> str:
wrapper = V.graph.wrapper_code
if src_code in wrapper.src_to_kernel:
kernel_name = wrapper.src_to_kernel[src_code]
else:
# TODO: Merge multiple kernels into a single library
# Either using MultiKernel concept or overriding SIMDScheduling.codegen_node_scheduling
mps_lib_name = f"mps_lib_{wrapper.next_kernel_suffix()}"
if V.graph.cpp_wrapper:
kernel_name = f"{mps_lib_name}_func"
else:
kernel_name = f"{mps_lib_name}.generated_kernel"
wrapper.src_to_kernel[src_code] = kernel_name
if V.graph.cpp_wrapper:
src_code = (
f"at::native::mps::DynamicMetalShaderLibrary {mps_lib_name}"
+ src_code
)
origins, detailed_origins = get_kernel_metadata(node_schedule, wrapper)
metadata_comment = f"{origins}\n{detailed_origins}"
wrapper.define_kernel(mps_lib_name, src_code, metadata_comment, gpu=False)
return kernel_name