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improve exp2 implementations
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@chriselrod
chriselrod committed May 26, 2024
1 parent d671ea7 commit 76e23b2
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Showing 2 changed files with 75 additions and 14 deletions.
2 changes: 1 addition & 1 deletion Project.toml
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
name = "VectorizationBase"
uuid = "3d5dd08c-fd9d-11e8-17fa-ed2836048c2f"
authors = ["Chris Elrod <[email protected]>"]
version = "0.21.67"
version = "0.21.68"

[deps]
ArrayInterface = "4fba245c-0d91-5ea0-9b3e-6abc04ee57a9"
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87 changes: 74 additions & 13 deletions src/special/exp.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -258,9 +258,9 @@ LogBINV(::Val{10}, ::Type{Float32}) = 3.321928f0
LogBU(::Val{2}, ::Type{Float32}) = -1.0f0
LogBU(::Val{ℯ}, ::Type{Float32}) = -0.6931472f0
LogBU(::Val{10}, ::Type{Float32}) = -0.30103f0
LogBL(base::Val{2}, ::Type{Float32}) = 0.0f0
LogBL(base::Val{ℯ}, ::Type{Float32}) = 1.9046542f-9
LogBL(base::Val{10}, ::Type{Float32}) = 1.4320989f-8
LogBL(::Val{2}, ::Type{Float32}) = 0.0f0
LogBL(::Val{ℯ}, ::Type{Float32}) = 1.9046542f-9
LogBL(::Val{10}, ::Type{Float32}) = 1.4320989f-8

const FloatType64 = Union{Float64,AbstractSIMD{<:Any,Float64}}
const FloatType32 = Union{Float32,AbstractSIMD{<:Any,Float32}}
Expand Down Expand Up @@ -547,7 +547,9 @@ end
# Because of the larger polynomial, this implementation works better on systems with 2 FMA units.

@inline function vexp2(x::AbstractSIMD{8,Float64}, ::True)
r = vsreduce(16.0x, Val(0)) * 0.0625
# M = 64 >> 4 = 4
# r = x - round(2^M * x)*2^-M
r = vsreduce(x, Val(64))
N_float = x - r
expr = expm1b_kernel_16(Val(2), r)
inds = convert(UInt64, vsreduce(N_float, Val(1)) * 16.0)
Expand Down Expand Up @@ -635,18 +637,77 @@ end
::Val{B}
) where {B}
N_float = vfmadd(x, LogBINV(Val{B}(), Float32), MAGIC_ROUND_CONST(Float32))
N = reinterpret(UInt32, N_float)
N_float = (N_float - MAGIC_ROUND_CONST(Float32))

r = fast_fma(N_float, LogBU(Val{B}(), Float32), x, fma_fast())
r = fast_fma(N_float, LogBL(Val{B}(), Float32), r, fma_fast())

r = fma(N_float, LogBU(Val{B}(), Float32), x)
r = fma(N_float, LogBL(Val{B}(), Float32), r)
small_part = expb_kernel(Val{B}(), r)
res = vscalef(small_part, N_float)
# twopk = N << 0x00000017
# res = reinterpret(Float32, twopk + small_part)
return res
return vscalef(small_part, N_float)
end
@inline function vexp2(x::AbstractSIMD{<:Any,Float32}, ::True)
r = vsreduce(x, Val(0))
N_float = x - r

small_part = expb_kernel(Val{2}(), r)
return vscalef(small_part, N_float)
end

# @inline function vexp_test(x::AbstractSIMD{16,Float32})#, ::True)
# xb = x * LogBINV(Val{ℯ}(), Float32)
# # rs = xb - round(xb)
# rs = vsreduce(xb, Val(0))
# N_float = xb - rs

# # rs = x*log2(ℯ) - N_float
# # r = fma(x, Float32(log2(ℯ)), - N_float)

# # rs = x*(l2_hi + l2_lo) - N_float
# # rs = x*l2_hi - N_float + x*l2_lo
# # r = fma(x, 1.925963f-8, rs)
# # small_part = expb_kernel(Val{2}(), r)
# # B = ℯ
# # r = fma(N_float, LogBU(Val{B}(), Float32), x)
# # r = fma(N_float, LogBL(Val{B}(), Float32), r)
# # small_part = expb_kernel(Val{B}(), r)

# rv2 = fma(1.442695f0, x, -N_float)
# rv2 = fma(1.925963f-8, x, rv2)
# small_part = expb_kernel(Val{2}(), rv2)

# # @show rs r rs / r rv2

# # xb = x * log2(ℯ )
# # rs = xb - N_float
# # rs = x * log2(ℯ) - N_float
# # vs, desierd:
# # r = x - N_float * log(2)
# # r = x - N_float / log2(ℯ)
# # r = rs / log2(ℯ)
# # r = 0.6931471805599453f0 * rs

# # small_part = expb_kernel(Val{2}(), r)
# return vscalef(small_part, N_float)
# end
# @inline vexp_test(x::AbstractSIMD{16}) = vexp_test(Float32(x))
# @inline vexp_test(x::Vec{8}) = shufflevector(
# vexp_test(
# shufflevector(
# x,
# x,
# Val((0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15))
# )
# ),
# Val((0, 1, 2, 3, 4, 5, 6, 7))
# )
# @inline vexp_test(x::Vec{4}) = shufflevector(
# vexp_test(shufflevector(x, x, Val((0, 1, 2, 3, 4, 5, 6, 7)))),
# Val((0, 1, 2, 3))
# )
# @inline vexp_test(x::Vec{2}) = shufflevector(
# vexp_test(shufflevector(x, x, Val((0, 1, 2, 3)))),
# Val((0, 1))
# )
# @inline vexp_test(x::VecUnroll) = VecUnroll(fmap(vexp_test, data(x)))
# @inline vexp_test(x::Float32) = vexp_test(Vec(x))(1)

else# if !((Sys.ARCH === :x86_64) | (Sys.ARCH === :i686))
const target_trunc = identity
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Registration pull request created: JuliaRegistries/General/107674

Tip: Release Notes

Did you know you can add release notes too? Just add markdown formatted text underneath the comment after the text
"Release notes:" and it will be added to the registry PR, and if TagBot is installed it will also be added to the
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@JuliaRegistrator register

Release notes:

## Breaking changes

- blah

To add them here just re-invoke and the PR will be updated.

Tagging

After the above pull request is merged, it is recommended that a tag is created on this repository for the registered package version.

This will be done automatically if the Julia TagBot GitHub Action is installed, or can be done manually through the github interface, or via:

git tag -a v0.21.68 -m "<description of version>" 76e23b2be46ea0a8cff35cd4d37e7fb910fb38d8
git push origin v0.21.68

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