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Revision f442e4230a41d0d40f81346c1707f946f743cbcf authored by Jeff Bezanson on 09 June 2021, 02:51:34 UTC, committed by GitHub on 09 June 2021, 02:51:34 UTC 
Add support for external method tables (#39697)
 
This PR implements a way to keep tables of methods that are
not part of the internal method table, but still participate
in the special support we have for keeping tables of methods,
in particular unification through precompilation and efficient
lookup. The intended design use case is to allow for method overlay
tables for various non-CPU backends (e.g. GPU and TPU). These
backends would like to modify basic function like `sin` to
perform better on the device in question (or in the case of TPU
to define them over non-LLVM intrinsics).

It is worth noting that this PR only gives the ability to keep
these tables of methods. It assigns no particular meaning to them
and the runtime (and regular inference) do not look at them.
They are designed as an implementation detail for external
compilers and similar tools.

 # Demo

```julia
julia> using Base.Experimental: @overlay, @MethodTable

julia> @MethodTable(mt)
 # 0 methods:

julia> @overlay mt function sin(x::Float64)
           1
       end

julia> @overlay mt function cos(x::Float64)
           1
       end

julia> mt
 # 2 methods:
[1] cos(x::Float64) in Main at REPL[5]:1
[2] sin(x::Float64) in Main at REPL[4]:1

julia> Base._methods_by_ftype(Tuple{typeof(sin), Float64}, mt, 1, typemax(UInt))
1-element Vector{Any}:
 Core.MethodMatch(Tuple{typeof(sin), Float64}, svec(), sin(x::Float64) in Main at REPL[4]:1, true)

julia> Base._methods_by_ftype(Tuple{typeof(sin), Float64}, 1, typemax(UInt))
1-element Vector{Any}:
 Core.MethodMatch(Tuple{typeof(sin), Float64}, svec(Float64), sin(x::T) where T<:Union{Float32, Float64} in Base.Math at special/trig.jl:29, true)
```

Co-authored-by: Tim Besard <tim.besard@gmail.com>
Co-authored-by: Julian P Samaroo <jpsamaroo@jpsamaroo.me>
Co-authored-by: Keno Fischer <keno@juliacomputing.com>
1 parent 0e3276c
Raw File
testenv.jl 
# This file is a part of Julia. License is MIT: https://julialang.org/license

# This includes a few helper variables and functions that provide information about the
# test environment (command line flags, current module, etc).
# This file can be included multiple times in the same module if necessary,
# which can happen with unisolated test runs.

if !@isdefined(testenv_defined)
    const testenv_defined = true
    if haskey(ENV, "JULIA_TEST_EXEFLAGS")
        const test_exeflags = `$(Base.shell_split(ENV["JULIA_TEST_EXEFLAGS"]))`
    else
        const test_exeflags = Base.julia_cmd()
        filter!(test_exeflags.exec) do c
            return !(startswith(c, "--depwarn") || startswith(c, "--check-bounds"))
        end
        push!(test_exeflags.exec, "--check-bounds=yes")
        push!(test_exeflags.exec, "--startup-file=no")
        push!(test_exeflags.exec, "--depwarn=error")
    end
    if haskey(ENV, "JULIA_TEST_EXTRA_EXEFLAGS")
        append!(test_exeflags.exec, Base.shell_split(ENV["JULIA_TEST_EXTRA_EXEFLAGS"]))
    end

    if haskey(ENV, "JULIA_TEST_EXENAME")
        popfirst!(test_exeflags.exec)
        const test_exename = `$(Base.shell_split(ENV["JULIA_TEST_EXENAME"]))`
    else
        const test_exename = popfirst!(test_exeflags.exec)
    end

    if haskey(ENV, "JULIA_RR")
        const rr_exename = `$(Base.shell_split(ENV["JULIA_RR"]))`
    else
        const rr_exename = ``
    end

    function addprocs_with_testenv(X; rr_allowed=true, kwargs...)
        exename = rr_allowed ? `$rr_exename $test_exename` : test_exename
        addprocs(X; exename=exename, exeflags=test_exeflags, kwargs...)
    end

    const curmod = @__MODULE__
    const curmod_name = fullname(curmod)
    const curmod_str = curmod === Main ? "Main" : join(curmod_name, ".")
    const curmod_prefix = "$(["$m." for m in curmod_name]...)"

    # platforms that support cfunction with closures
    # (requires LLVM back-end support for trampoline intrinsics)
    const cfunction_closure = Sys.ARCH === :x86_64 || Sys.ARCH === :i686

    macro async_logerr(expr)
        :(@async try
            $(esc(expr))
        catch err
            @error("An async task failed", exception=(err, catch_backtrace()))
        end)
    end
end
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