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Respect NaN-safe mode in fma and muladd #861

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Respect NaN-safe mode in fma and muladd #861

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8 changes: 4 additions & 4 deletions src/dual.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -625,7 +625,7 @@ end
@generated function calc_fma_xyz(x::Dual{T,<:Any,N},
y::Dual{T,<:Any,N},
z::Dual{T,<:Any,N}) where {T,N}
ex = Expr(:tuple, [:(fma(value(x), partials(y)[$i], fma(value(y), partials(x)[$i], partials(z)[$i]))) for i in 1:N]...)
ex = Expr(:tuple, [:(_fma_partial(value(x), partials(y, $i), _fma_partial(value(y), partials(x, $i), partials(z, $i)))) for i in 1:N]...)
return quote
$(Expr(:meta, :inline))
v = fma(value(x), value(y), value(z))
Expand All @@ -642,7 +642,7 @@ end
@generated function calc_fma_xz(x::Dual{T,<:Any,N},
y::Real,
z::Dual{T,<:Any,N}) where {T,N}
ex = Expr(:tuple, [:(fma(partials(x)[$i], y, partials(z)[$i])) for i in 1:N]...)
ex = Expr(:tuple, [:(_fma_partial(y, partials(x, $i), partials(z, $i))) for i in 1:N]...)
return quote
$(Expr(:meta, :inline))
v = fma(value(x), y, value(z))
Expand All @@ -667,7 +667,7 @@ end
@generated function calc_muladd_xyz(x::Dual{T,<:Any,N},
y::Dual{T,<:Any,N},
z::Dual{T,<:Any,N}) where {T,N}
ex = Expr(:tuple, [:(muladd(value(x), partials(y)[$i], muladd(value(y), partials(x)[$i], partials(z)[$i]))) for i in 1:N]...)
ex = Expr(:tuple, [:(_muladd_partial(value(x), partials(y, $i), _muladd_partial(value(y), partials(x, $i), partials(z, $i)))) for i in 1:N]...)
return quote
$(Expr(:meta, :inline))
v = muladd(value(x), value(y), value(z))
Expand All @@ -684,7 +684,7 @@ end
@generated function calc_muladd_xz(x::Dual{T,<:Any,N},
y::Real,
z::Dual{T,<:Any,N}) where {T,N}
ex = Expr(:tuple, [:(muladd(partials(x)[$i], y, partials(z)[$i])) for i in 1:N]...)
ex = Expr(:tuple, [:(_muladd_partial(y, partials(x, $i), partials(z, $i))) for i in 1:N]...)
return quote
$(Expr(:meta, :inline))
v = muladd(value(x), y, value(z))
Expand Down
10 changes: 10 additions & 0 deletions src/partials.jl
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Expand Up @@ -117,9 +117,19 @@ if NANSAFE_MODE_ENABLED
y = partial / x
return iszero(partial) ? zero(y) : y
end
@inline function _fma_partial(x::Real, partial::Real, acc::Real)
y = fma(x, partial, acc)
return iszero(partial) ? oftype(y, acc) : y
end
@inline function _muladd_partial(x::Real, partial::Real, acc::Real)
y = muladd(x, partial, acc)
return iszero(partial) ? oftype(y, acc) : y
end
else
@inline _mul_partial(partial::Real, x::Real) = partial * x
@inline _div_partial(partial::Real, x::Real) = partial / x
@inline _fma_partial(x::Real, partial::Real, acc::Real) = fma(x, partial, acc)
@inline _muladd_partial(x::Real, partial::Real, acc::Real) = muladd(x, partial, acc)
end

# edge cases where N == 0 #
Expand Down
14 changes: 14 additions & 0 deletions test/DualTest.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -761,4 +761,18 @@ end
end
end

@testset "fma and muladd: consistency with `x * y + z`" begin # issue #860
for f in (fma, muladd)
for (x, y, z) in (
(Dual{TestTag}(Inf, 0.0), Dual{TestTag}(2.0, 0.0), Dual{TestTag}(0.0, 1.0)),
(Dual{TestTag}(1.0, 0.0), Inf, Dual{TestTag}(0.0, 1.0)),
(Inf, Dual{TestTag}(1.0, 0.0), Dual{TestTag}(0.0, 1.0)),
)
d = f(x, y, z)
@test value(d) === Inf
@test isequal(d, x * y + z)
end
end
end

end # module
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