cubecl_reduce/instructions/
max.rs

1use cubecl_core as cubecl;
2use cubecl_core::prelude::*;
3
4use crate::instructions::ReduceRequirements;
5
6use super::{ReduceCoordinate, ReduceFamily, ReduceInstruction};
7
8// TODO Add to test framework.
9/// Return the item with the maximum value.
10#[derive(Debug, CubeType, Clone)]
11pub struct Max;
12
13impl ReduceFamily for Max {
14    type Instruction<In: Numeric> = Self;
15    type Config = ();
16}
17
18#[cube]
19impl<In: Numeric> ReduceInstruction<In> for Max {
20    type AccumulatorItem = Line<In>;
21    type SharedAccumulator = SharedMemory<Line<In>>;
22    type Config = ();
23
24    fn requirements(_this: &Self) -> ReduceRequirements {
25        ReduceRequirements { coordinates: false }
26    }
27
28    fn from_config(_config: Self::Config) -> Self {
29        Max {}
30    }
31
32    fn null_input(_this: &Self, #[comptime] line_size: u32) -> Line<In> {
33        Line::empty(line_size).fill(In::min_value())
34    }
35
36    fn null_accumulator(this: &Self, #[comptime] line_size: u32) -> Self::AccumulatorItem {
37        Self::null_input(this, line_size)
38    }
39
40    fn assign_accumulator(
41        _this: &Self,
42        destination: &mut Self::AccumulatorItem,
43        source: &Self::AccumulatorItem,
44    ) {
45        *destination = *source;
46    }
47
48    fn reduce(
49        _this: &Self,
50        accumulator: &Self::AccumulatorItem,
51        item: Line<In>,
52        _coordinate: ReduceCoordinate,
53        #[comptime] use_planes: bool,
54    ) -> Self::AccumulatorItem {
55        if use_planes {
56            let candidate_item = plane_max(item);
57            select_many(
58                accumulator.greater_than(candidate_item),
59                *accumulator,
60                candidate_item,
61            )
62        } else {
63            select_many(accumulator.greater_than(item), *accumulator, item)
64        }
65    }
66
67    fn fuse_accumulators(
68        _this: &Self,
69        lhs: Self::AccumulatorItem,
70        rhs: Self::AccumulatorItem,
71    ) -> Self::AccumulatorItem {
72        select_many(lhs.greater_than(rhs), lhs, rhs)
73    }
74
75    fn merge_line<Out: Numeric>(
76        _this: &Self,
77        accumulator: Self::AccumulatorItem,
78        _shape_axis_reduce: u32,
79    ) -> Out {
80        let mut max = In::min_value();
81        #[unroll]
82        for k in 0..accumulator.size() {
83            let candidate = accumulator[k];
84            max = select(candidate > max, candidate, max);
85        }
86        Out::cast_from(max)
87    }
88
89    fn to_output_perpendicular<Out: Numeric>(
90        _this: &Self,
91        accumulator: Self::AccumulatorItem,
92        _shape_axis_reduce: u32,
93    ) -> Line<Out> {
94        Line::cast_from(accumulator)
95    }
96}
cubecl_reduce/instructions/max.rs

cubecl_reduce/instructions/
max.rs
