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Chris Tate
9406ba5b89
A loop nest that sums one term per row,
for (let i = start; i < end; i++) {
let t = 0;
for (let j = from; j < to; j++) t += term;
out[i] = t;
}
where the term only reads numbers, the counters and typed-array
elements, now runs two rows per pass when both row bounds are int32,
the start is at most the end, and the stored array shares no byte with
any array the term reads. Each row keeps its order of additions, so each
sum has the bits of the loop as written; an odd row count runs its last
row as written, and any other case runs the nest as written. Element
reads that do not depend on the row are read once per column for both
rows. With two independent sums in the inner loop, neither waits on the
other's addition, and LLVM computes both rows' terms in one vector.
bytes.disjoint compares two typed arrays' element ranges in memory.