108 lines
4.0 KiB
Python
108 lines
4.0 KiB
Python
# Licensed to the Apache Software Foundation (ASF) under one
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# or more contributor license agreements. See the NOTICE file
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# distributed with this work for additional information
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# regarding copyright ownership. The ASF licenses this file
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# to you under the Apache License, Version 2.0 (the
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# "License"); you may not use this file except in compliance
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# with the License. You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing,
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# software distributed under the License is distributed on an
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# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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# KIND, either express or implied. See the License for the
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# specific language governing permissions and limitations
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# under the License.
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# pylint: disable=missing-docstring
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"""A fallback schedule rule for GPU operators."""
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from tvm import s_tir, tirx
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from tvm.target import Target
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from .. import base
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from ..analysis import normalize_prim_func
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from ..base import try_inline
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from .base import GPUScheduleRule
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def _has_internal_thread_env(stmt: tirx.Stmt) -> bool:
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"""Check whether a statement already launches GPU threads internally,
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e.g. via `T.launch_thread` (AttrStmt "thread_extent") or nested
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thread-bound loops. Such blocks manage their own thread environment
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and must not be wrapped in an additional thread binding."""
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found = False
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def _visit(node):
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nonlocal found
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if isinstance(node, tirx.AttrStmt) and node.attr_key in ("thread_extent", "virtual_thread"):
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found = True
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elif isinstance(node, tirx.For) and node.kind == tirx.ForKind.THREAD_BINDING:
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found = True
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tirx.stmt_functor.post_order_visit(stmt, _visit)
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return found
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class Fallback(GPUScheduleRule):
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"""
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A fallback schedule rule for all GPU operators. It will try to inline all the blocks first,
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and then apply a simple block/grid mapping to the spatial loops on top of the remaining blocks.
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"""
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def apply( # pylint: disable=too-many-locals,missing-docstring
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self,
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func: tirx.PrimFunc,
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target: Target,
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_: bool,
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) -> s_tir.Schedule:
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if not isinstance(func, tirx.PrimFunc) or not self.is_target_available(target):
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return None
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max_threads_per_block = base.max_threads_per_block(target)
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sch = s_tir.Schedule(func)
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block_infos = normalize_prim_func(sch)
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if block_infos is None:
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return None
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block_infos = try_inline(sch, block_infos)
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reduction_blocks: list[tuple[s_tir.schedule.SBlockRV, s_tir.schedule.LoopRV]] = []
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for block in block_infos:
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s_loops: list[s_tir.schedule.LoopRV] = []
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r_loops: list[s_tir.schedule.LoopRV] = []
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o_loops: list[s_tir.schedule.LoopRV] = []
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dom_kind = block.dom_kind()
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block = block.block_rv
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if any(
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[sch.get(loop_rv).thread_binding is not None for loop_rv in sch.get_loops(block)]
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):
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continue
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if len(sch.get_loops(block)) == 0 and _has_internal_thread_env(sch.get(block).body):
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# The block (e.g. an opaque sort kernel) launches its own
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# threads; binding an outer loop would conflict with them.
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continue
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for loop, iter_type in zip(sch.get_loops(block), dom_kind):
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{"S": s_loops, "R": r_loops, "O": o_loops}[iter_type].append(loop)
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if not s_loops:
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s_loops.append(sch.add_unit_loop(block))
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sch.reorder(*s_loops, *r_loops, *o_loops)
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bx, tx = sch.split( # pylint: disable=invalid-name
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sch.fuse(*s_loops),
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factors=[None, max_threads_per_block],
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)
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sch.bind(bx, "blockIdx.x")
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sch.bind(tx, "threadIdx.x")
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if len(r_loops) > 0:
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reduction_blocks.append((block, r_loops[0]))
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for block, r_loop in reduction_blocks:
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sch.decompose_reduction(block, r_loop)
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return sch
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