Avoid most boxes in precompilation code

[KristofferC]

• Use local where variable names accidentally overlapped and caused boxes
• Use @lock to avoid closures
• Move out some recursive closures to top-level normal function to avoid boxing them
• Use explicit boxes (Ref) instead of relying on the typeassert on the Core.Box because it it hard to determine if a Core.Box is benign or not.
• Only assign to io once to avoid boxing it.

The two remaining boxes after this is t_print and monitor_std.

[JeffBezanson]

Is there a visible performance or latency benefit from this? Just curious.

[KristofferC]

I've seen invalidations from some things that are fixed here, for example:

julia> trees[2]
inserting issubset(iterable, m2::DataStructures.SortedSet) @ DataStructures ~/.julia/packages/DataStructures/IrAJn/src/sorted_set.jl:504 invalidated:
   backedges: 1: superseding issubset(a, b) @ Base abstractset.jl:329 with MethodInstance for issubset(::Vector{Base.PkgId}, ::Any) (1 children)

julia> trees[2].backedges[1].children
1-element Vector{SnoopCompile.InstanceNode}:
 MethodInstance for Base.Precompilation._precompilepkgs(::Vector{String}, ::Bool, ::Bool, ::Bool, ::Bool, ::Bool, ::Vector{Pair{Cmd, Base.CacheFlags}}, ::IOContext{IO}, ::Bool, ::Bool) at depth 1 with 0 children

Also, if you check what signatures are compiled on a Pkg.add you see these signatures which are claimed to be from invalidations.

#=   39.2 ms =# precompile(Tuple{Base.Precompilation.var"#_precompilepkgs##33#_precompilepkgs##34"{Bool, Array{Pair{Base.Cmd, Base.CacheFlags}, 1}, Bool, Base.Dict{Tuple{Base.PkgId, Pair{Base.Cmd, Base.CacheFlags}}, String}, Base.Set{Tuple{Base.PkgId, Pair{Base.Cmd, Base.CacheFlags}}}, String, String, String, String, Base.Precompilation.var"#ansi_moveup#_precompilepkgs##21", Base.Event, Base.Event, Base.ReentrantLock, Array{Tuple{Base.PkgId, Pair{Base.Cmd, Base.CacheFlags}}, 1}, Base.Dict{Tuple{Base.PkgId, Pair{Base.Cmd, Base.CacheFlags}}, String}, Array{Tuple{Base.PkgId, Pair{Base.Cmd, Base.CacheFlags}}, 1}, Base.Dict{Tuple{Base.PkgId, Pair{Base.Cmd, Base.CacheFlags}}, Bool}, Base.Dict{Tuple{Base.PkgId, Pair{Base.Cmd, Base.CacheFlags}}, Bool}, Array{Base.PkgId, 1}, Base.Precompilation.var"#describe_pkg#_precompilepkgs##1"{Base.Dict{Base.PkgId, Base.PkgId}, Base.Precompilation.var"#color_string#_precompilepkgs##0"{Bool}, Int64}, Base.Dict{Base.PkgId, Array{Base.PkgId, 1}}, Base.Precompilation.var"#color_string#_precompilepkgs##0"{Bool}}}) # recompile

#=   88.6 ms =# precompile(Tuple{Base.Precompilation.var"#_precompilepkgs##47#_precompilepkgs##48"{Bool, Bool, Bool, Array{Task, 1}, Base.Dict{Tuple{Base.PkgId, Pair{Base.Cmd, Base.CacheFlags}}, String}, Base.Dict{Tuple{Base.PkgId, Pair{Base.Cmd, Base.CacheFlags}}, Base.GenericIOBuffer{Memory{UInt8}}}, Base.Event, Base.Event, Base.ReentrantLock, Array{Tuple{Base.PkgId, Pair{Base.Cmd, Base.CacheFlags}}, 1}, Base.Dict{Tuple{Base.PkgId, Pair{Base.Cmd, Base.CacheFlags}}, String}, Array{Tuple{Base.PkgId, Pair{Base.Cmd, Base.CacheFlags}}, 1}, Array{Base.PkgId, 1}, Base.Dict{Tuple{Base.PkgId, Pair{Base.Cmd, Base.CacheFlags}}, Bool}, Base.Dict{Tuple{Base.PkgId, Pair{Base.Cmd, Base.CacheFlags}}, Base.Event}, Base.Dict{Tuple{Base.PkgId, Pair{Base.Cmd, Base.CacheFlags}}, Bool}, Array{Base.PkgId, 1}, Base.Precompilation.var"#describe_pkg#_precompilepkgs##1"{Base.Dict{Base.PkgId, Base.PkgId}, Base.Precompilation.var"#color_string#_precompilepkgs##0"{Bool}, Int64}, Base.Dict{Base.PkgId, Base.PkgId}, Base.Dict{Base.PkgId, Array{Base.PkgId, 1}}, Base.Dict{Base.PkgId, Array{String, 1}}, Base.Dict{Tuple{Base.PkgId, UInt128, String, String}, Bool}, Base.Precompilation.var"#color_string#_precompilepkgs##0"{Bool}, Bool, Base.Semaphore, Bool, String, Array{String, 1}, Array{Base.PkgId, 1}, Base.PkgId, Base.CacheFlags, Base.Cmd, Pair{Base.Cmd, Base.CacheFlags}, Tuple{Base.PkgId, Pair{Base.Cmd, Base.CacheFlags}}}}) # recompile

I should check that these are gone with this PR though.

[nsajko]

Prevents the following method instances in the sysimage from being invalidated:

{
    "method_instance": {
        "method": "(var\"#monitor_std\"::Base.Precompilation.var\"#monitor_std#18#_precompilepkgs##26\")(single_requested_pkg, ::Base.Precompilation.var\"#monitor_std#_precompilepkgs##25\", pkg_config, pipe) @ Base.Precompilation precompilation.jl:762",
        "method_instance": "MethodInstance for (::Base.Precompilation.var\"#monitor_std#18#_precompilepkgs##26\"{Bool, Set{Tuple{Base.PkgId, Pair{Cmd, Base.CacheFlags}}}, Dict{Tuple{Base.PkgId, Pair{Cmd, Base.CacheFlags}}, IOBuffer}, String, ReentrantLock, Base.Precompilation.var\"#color_string#_precompilepkgs##0\"{Bool}})(::Bool, ::Base.Precompilation.var\"#monitor_std#_precompilepkgs##25\"{Base.Precompilation.var\"#monitor_std#18#_precompilepkgs##26\"{Bool, Set{Tuple{Base.PkgId, Pair{Cmd, Base.CacheFlags}}}, Dict{Tuple{Base.PkgId, Pair{Cmd, Base.CacheFlags}}, IOBuffer}, String, ReentrantLock, Base.Precompilation.var\"#color_string#_precompilepkgs##0\"{Bool}}}, ::Tuple{Base.PkgId, Pair{Cmd, Base.CacheFlags}}, ::Pipe)"
    },
    "children": [
    ]
}

{
    "method_instance": {
        "method": "(var\"#monitor_std\"::Base.Precompilation.var\"#monitor_std#18#_precompilepkgs##26\")(single_requested_pkg, ::Base.Precompilation.var\"#monitor_std#_precompilepkgs##25\", pkg_config, pipe) @ Base.Precompilation precompilation.jl:762",
        "method_instance": "MethodInstance for (::Base.Precompilation.var\"#monitor_std#18#_precompilepkgs##26\"{Bool, Set{Tuple{Base.PkgId, Pair{Cmd, Base.CacheFlags}}}, Dict{Tuple{Base.PkgId, Pair{Cmd, Base.CacheFlags}}, IOBuffer}, String, ReentrantLock, Base.Precompilation.var\"#color_string#_precompilepkgs##0\"{Bool}})(::Bool, ::Base.Precompilation.var\"#monitor_std#_precompilepkgs##25\"{Base.Precompilation.var\"#monitor_std#18#_precompilepkgs##26\"{Bool, Set{Tuple{Base.PkgId, Pair{Cmd, Base.CacheFlags}}}, Dict{Tuple{Base.PkgId, Pair{Cmd, Base.CacheFlags}}, IOBuffer}, String, ReentrantLock, Base.Precompilation.var\"#color_string#_precompilepkgs##0\"{Bool}}}, ::Tuple{Base.PkgId, Pair{Cmd, Base.CacheFlags}}, ::Pipe)"
    },
    "children": [
    ]
}

{
    "method_instance": {
        "method": "(var\"#monitor_std\"::Base.Precompilation.var\"#monitor_std#18#_precompilepkgs##26\")(single_requested_pkg, ::Base.Precompilation.var\"#monitor_std#_precompilepkgs##25\", pkg_config, pipe) @ Base.Precompilation precompilation.jl:762",
        "method_instance": "MethodInstance for (::Base.Precompilation.var\"#monitor_std#18#_precompilepkgs##26\"{Bool, Set{Tuple{Base.PkgId, Pair{Cmd, Base.CacheFlags}}}, Dict{Tuple{Base.PkgId, Pair{Cmd, Base.CacheFlags}}, IOBuffer}, String, ReentrantLock, Base.Precompilation.var\"#color_string#_precompilepkgs##0\"{Bool}})(::Bool, ::Base.Precompilation.var\"#monitor_std#_precompilepkgs##25\"{Base.Precompilation.var\"#monitor_std#18#_precompilepkgs##26\"{Bool, Set{Tuple{Base.PkgId, Pair{Cmd, Base.CacheFlags}}}, Dict{Tuple{Base.PkgId, Pair{Cmd, Base.CacheFlags}}, IOBuffer}, String, ReentrantLock, Base.Precompilation.var\"#color_string#_precompilepkgs##0\"{Bool}}}, ::Tuple{Base.PkgId, Pair{Cmd, Base.CacheFlags}}, ::Pipe)"
    },
    "children": [
        {
            "method_instance": {
                "method": "kwcall(::NamedTuple, ::Base.Precompilation.var\"#monitor_std#_precompilepkgs##25\", pkg_config, pipe) @ Base.Precompilation precompilation.jl:762",
                "method_instance": "MethodInstance for Core.kwcall(::@NamedTuple{single_requested_pkg::Bool}, ::Base.Precompilation.var\"#monitor_std#_precompilepkgs##25\"{Base.Precompilation.var\"#monitor_std#18#_precompilepkgs##26\"{Bool, Set{Tuple{Base.PkgId, Pair{Cmd, Base.CacheFlags}}}, Dict{Tuple{Base.PkgId, Pair{Cmd, Base.CacheFlags}}, IOBuffer}, String, ReentrantLock, Base.Precompilation.var\"#color_string#_precompilepkgs##0\"{Bool}}}, ::Tuple{Base.PkgId, Pair{Cmd, Base.CacheFlags}}, ::Pipe)"
            },
            "children": [
            ]
        }
    ]
}

Full data:

• master-2f34760fb2.json
• pr__KristofferC__prec_boxes.json

These sysimage invalidations happen on master when running the following code as a user:

struct S <: AbstractString end
function Base.thisind(::S, ::Int) end