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arrayunset: micro-optimization for performance #32405

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Merged
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Jun 26, 2019
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arrayunset: micro-optimization for performance #32405

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14 changes: 14 additions & 0 deletions base/array.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -175,6 +175,20 @@ false
isbitsunion(u::Union) = (@_pure_meta; ccall(:jl_array_store_unboxed, Cint, (Any,), u) != Cint(0))
isbitsunion(x) = false

isptrelement(t::Type) = (@_pure_meta; ccall(:jl_array_store_unboxed, Cint, (Any,), t) == Cint(0))
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@quinnj quinnj Jun 24, 2019

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we already define this here, so maybe we should consolidate.

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@vtjnash vtjnash Jun 24, 2019

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It's not quite the same, since the other query is related to this query by the formula isbitsunion(u) = u isa Union && isptrelement(u)

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@quinnj quinnj Jun 24, 2019

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Right; I was mainly pointing out that maybe we should define a single ccall definition for this (and have isbitsunion call that), just to minimize the need to update things in two places if jl_array_store_unboxed ever changes.


function _unsetindex!(A::Array{T}, i::Int) where {T}
@boundscheck checkbounds(A, i)
if isptrelement(T)
t = @_gc_preserve_begin A
p = Ptr{Ptr{Cvoid}}(pointer(A))
unsafe_store!(p, C_NULL, i)
@_gc_preserve_end t
end
return A
end


"""
Base.bitsunionsize(U::Union)

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4 changes: 2 additions & 2 deletions base/dict.jl
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Expand Up @@ -620,8 +620,8 @@ end

function _delete!(h::Dict{K,V}, index) where {K,V}
@inbounds h.slots[index] = 0x2
isbitstype(K) || isbitsunion(K) || ccall(:jl_arrayunset, Cvoid, (Any, UInt), h.keys, index-1)
isbitstype(V) || isbitsunion(V) || ccall(:jl_arrayunset, Cvoid, (Any, UInt), h.vals, index-1)
@inbounds _unsetindex!(h.keys, index)
@inbounds _unsetindex!(h.vals, index)
h.ndel += 1
h.count -= 1
h.age += 1
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5 changes: 2 additions & 3 deletions src/array.c
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Expand Up @@ -592,10 +592,9 @@ JL_DLLEXPORT void jl_arrayset(jl_array_t *a JL_ROOTING_ARGUMENT, jl_value_t *rhs
JL_DLLEXPORT void jl_arrayunset(jl_array_t *a, size_t i)
{
if (i >= jl_array_len(a))
jl_bounds_error_int((jl_value_t*)a, i+1);
char *ptail = (char*)a->data + i*a->elsize;
jl_bounds_error_int((jl_value_t*)a, i + 1);
if (a->flags.ptrarray)
memset(ptail, 0, a->elsize);
((jl_value_t**)a->data)[i] = NULL;
}

// at this size and bigger, allocate resized array data with malloc
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