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Specialize non-reducing kernel: drop reduction-only iszero hoist #69

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Merged
lkdvos merged 1 commit into from
Jul 10, 2026
Merged

Specialize non-reducing kernel: drop reduction-only iszero hoist #69

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79 changes: 51 additions & 28 deletions src/mapreduce.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -351,40 +351,63 @@ function _mapreduce_kernel_expr(f, op, initop, N::Int, M::Int)
firststrides = Expr(:tuple, (stridevars[1, j] for j in 1:M)...)
unitstridecond = :(all(==(1), $firststrides))

i = 1
if op == Nothing
# Non-reducing (map!/permute/...): each destination element is written once,
# so skip the reduction-only `iszero` hoist below and emit just the
# unit-stride and generic `@simd` loops.
ex = Expr(:(=), lhsex, fcallex)
exa = Expr(:(=), :a, fcallex)
if N >= 1
ex = quote
if $unitstridecond
@simd for $(innerloopvars[i]) in Base.OneTo($(blockdimvars[i]))
$ex
$unitstep1ex
$unitstep2ex
end
$(returnstride1ex[i])
$(returnstride2ex[i])
else
@simd for $(innerloopvars[i]) in Base.OneTo($(blockdimvars[i]))
$ex
$(stepstride1ex[i])
$(stepstride2ex[i])
end
$(returnstride1ex[i])
$(returnstride2ex[i])
end
end
end
else
ex = Expr(:(=), lhsex, Expr(:call, :op, lhsex, fcallex))
exa = Expr(:(=), :a, Expr(:call, :op, :a, fcallex))
end
i = 1
if N >= 1
ex = quote
if iszero($(stridevars[1, 1])) # explicitly hoist A1[I1] out of loop
a = $lhsex
@simd for $(innerloopvars[i]) in Base.OneTo($(blockdimvars[i]))
$exa
$(stepstride2ex[i])
end
$lhsex = a
$(returnstride2ex[i])
elseif $unitstridecond
@simd for $(innerloopvars[i]) in Base.OneTo($(blockdimvars[i]))
$ex
$unitstep1ex
$unitstep2ex
end
$(returnstride1ex[i])
$(returnstride2ex[i])
else
@simd for $(innerloopvars[i]) in Base.OneTo($(blockdimvars[i]))
$ex
$(stepstride1ex[i])
$(stepstride2ex[i])
if N >= 1
ex = quote
if iszero($(stridevars[1, 1])) # explicitly hoist A1[I1] out of loop
a = $lhsex
@simd for $(innerloopvars[i]) in Base.OneTo($(blockdimvars[i]))
$exa
$(stepstride2ex[i])
end
$lhsex = a
$(returnstride2ex[i])
elseif $unitstridecond
@simd for $(innerloopvars[i]) in Base.OneTo($(blockdimvars[i]))
$ex
$unitstep1ex
$unitstep2ex
end
$(returnstride1ex[i])
$(returnstride2ex[i])
else
@simd for $(innerloopvars[i]) in Base.OneTo($(blockdimvars[i]))
$ex
$(stepstride1ex[i])
$(stepstride2ex[i])
end
$(returnstride1ex[i])
$(returnstride2ex[i])
end
$(returnstride1ex[i])
$(returnstride2ex[i])
end
end
end
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