more efficient muladd for complex/real operations #15980
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Here's an oddity. If I do Clearly, the optimizer is doing the right thing at the end, as indicated by |
stevengj
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| muladd(z::Complex, x::Real, y::Real) = Complex(muladd(real(z),x,y), imag(z)*x) | ||
| muladd(z::Complex, x::Real, w::Complex) = | ||
| Complex(muladd(real(z),x,real(w)), muladd(imag(z),x,imag(w))) | ||
| muladd(x::Real, y::Real, z::Complex) = Complex(muladd(x,y,real(z)), imag(z)) |
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This leaves out the case (Complex, Complex, Real). Is this intentional? If so, a comment might make sense.
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Yes, it was intentional. All of the benefit from the muladd(Complex, Complex, Real) case could be gained by using muladd in Complex*Complex
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Wouldn't this save one addition?
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@eschnett, no, because there is already an addition in both the real and imaginary parts of Complex*Complex that could be fused with one of the multiplications.
Oh wait, you're right; you could save an extra addition.
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Okay, added the Complex*Complex cases
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| @@ -904,6 +904,11 @@ end | |||
| # issue #10926 | |||
| @test typeof(π - 1im) == Complex{Float64} | |||
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| # issue #15969: specialized muladd for complex types | |||
| for x in (3, 3+13im), y in (2, 2+7im), z in (5, 5+11im) | |||
| @test muladd(x,y,z) == x*y + z | |||
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They are Complex{Int} values, so what does it matter?
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to test that the return type stays that way
Fixes #15969, and corrects some efficiency problems in
@evalpolyintroduced in #9881.