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//! Reverse CSR frontier expansion over an in-place accumulator bitset.
use std::sync::Arc;
use vyre_foundation::ir::model::expr::Ident;
use vyre_foundation::ir::{BufferAccess, BufferDecl, DataType, Expr, Node, Program};
use crate::graph::csr_forward_traverse::bitset_words;
use crate::graph::program_graph::{
ProgramGraphShape, BINDING_PRIMITIVE_START, NAME_EDGE_KIND_MASK, NAME_EDGE_OFFSETS,
NAME_EDGE_TARGETS,
};
/// Canonical op id.
pub const OP_ID: &str = "vyre-primitives::graph::csr_backward_or_changed";
/// Parallel in-place reverse expansion program for resident fixed-point drivers.
#[must_use]
pub fn csr_backward_or_changed_parallel(
shape: ProgramGraphShape,
frontier_out: &str,
changed: &str,
edge_kind_mask: u32,
) -> Program {
let src = Expr::InvocationId { axis: 0 };
let words = bitset_words(shape.node_count);
let body = vec![
Node::let_bind("edge_start", Expr::load(NAME_EDGE_OFFSETS, src.clone())),
Node::let_bind(
"edge_end",
Expr::load(NAME_EDGE_OFFSETS, Expr::add(src.clone(), Expr::u32(1))),
),
Node::let_bind("hit", Expr::u32(0)),
Node::loop_for(
"e",
Expr::var("edge_start"),
Expr::var("edge_end"),
vec![Node::if_then(
Expr::eq(Expr::var("hit"), Expr::u32(0)),
vec![
Node::let_bind("kind_mask", Expr::load(NAME_EDGE_KIND_MASK, Expr::var("e"))),
Node::if_then(
Expr::ne(
Expr::bitand(Expr::var("kind_mask"), Expr::u32(edge_kind_mask)),
Expr::u32(0),
),
vec![
Node::let_bind("dst", Expr::load(NAME_EDGE_TARGETS, Expr::var("e"))),
Node::if_then(
Expr::lt(Expr::var("dst"), Expr::u32(shape.node_count)),
vec![
Node::let_bind(
"dst_word",
Expr::load(
frontier_out,
Expr::shr(Expr::var("dst"), Expr::u32(5)),
),
),
Node::let_bind(
"dst_bit",
Expr::shl(
Expr::u32(1),
Expr::bitand(Expr::var("dst"), Expr::u32(31)),
),
),
Node::if_then(
Expr::ne(
Expr::bitand(
Expr::var("dst_word"),
Expr::var("dst_bit"),
),
Expr::u32(0),
),
vec![Node::assign("hit", Expr::u32(1))],
),
],
),
],
),
],
)],
),
Node::if_then(
Expr::eq(Expr::var("hit"), Expr::u32(1)),
vec![
Node::let_bind("src_word_idx", Expr::shr(src.clone(), Expr::u32(5))),
Node::let_bind(
"src_bit",
Expr::shl(Expr::u32(1), Expr::bitand(src.clone(), Expr::u32(31))),
),
Node::let_bind(
"old",
Expr::atomic_or(
frontier_out,
Expr::var("src_word_idx"),
Expr::var("src_bit"),
),
),
Node::if_then(
Expr::eq(
Expr::bitand(Expr::var("old"), Expr::var("src_bit")),
Expr::u32(0),
),
vec![Node::let_bind(
"_changed",
Expr::atomic_or(changed, Expr::u32(0), Expr::u32(1)),
)],
),
],
),
];
let mut buffers = shape.read_only_buffers();
buffers.push(
BufferDecl::storage(
frontier_out,
BINDING_PRIMITIVE_START,
BufferAccess::ReadWrite,
DataType::U32,
)
.with_count(words),
);
buffers.push(
BufferDecl::storage(
changed,
BINDING_PRIMITIVE_START + 1,
BufferAccess::ReadWrite,
DataType::U32,
)
.with_count(1),
);
Program::wrapped(
buffers,
[1, 1, 1],
vec![Node::Region {
generator: Ident::from(OP_ID),
source_region: None,
body: Arc::new(vec![Node::if_then(
Expr::lt(src.clone(), Expr::u32(shape.node_count)),
body,
)]),
}],
)
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn exposes_frontier_and_changed_bindings() {
let program = csr_backward_or_changed_parallel(
ProgramGraphShape::new(4, 3),
"frontier",
"changed",
u32::MAX,
);
let names = program
.buffers()
.iter()
.map(|buffer| buffer.name())
.collect::<Vec<_>>();
assert!(names.contains(&"frontier"));
assert!(names.contains(&"changed"));
}
}