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Make threadcall gc safe #55956

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Make threadcall gc safe #55956

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c335d2e
Make threadcall gc safe
gbaraldi Oct 1, 2024
d4108ef
Make the call convert before entering the gc safe region. Also preser…
gbaraldi Oct 2, 2024
463c01a
Merge branch 'master' into gb/threadcall-gc
gbaraldi Oct 7, 2024
78bf3cc
Merge branch 'master' into gb/threadcall-gc
gbaraldi Oct 15, 2024
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14 changes: 10 additions & 4 deletions base/threadcall.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -39,13 +39,19 @@ macro threadcall(f, rettype, argtypes, argvals...)
args = Symbol[]
for (i, T) in enumerate(argtypes)
arg = Symbol("arg", i)
push!(body, :($arg = unsafe_load(convert(Ptr{$T}, p))))
push!(body, :($arg = unsafe_convert($T, cconvert($T, unsafe_load(convert(Ptr{$T}, p))))))
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I don't fully understand the code here (why is there an unsafe_load), but the return from cconvert must be GC preserved.

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Threadcall passes the args in an array of ptrs if I understood the code correctly

push!(body, :(p += Core.sizeof($T)))
push!(args, arg)
end
push!(body, :(ret = ccall(fptr, $rettype, ($(argtypes...),), $(args...))))
push!(body, :(unsafe_store!(convert(Ptr{$rettype}, retval_ptr), ret)))
push!(body, :(return Int(Core.sizeof($rettype))))
append!(body, (quote
GC.@preserve $(args...) begin
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@vchuravy vchuravy Oct 16, 2024 •
edited by giordano
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You are preserving the unsafe_convert not the cconvert here, right?

gc_state = ccall(:jl_gc_safe_enter, Int8, ())
ret = ccall(fptr, $rettype, ($(argtypes...),), $(args...))
ccall(:jl_gc_safe_leave, Cvoid, (Int8,), gc_state)
unsafe_store!(convert(Ptr{$rettype}, retval_ptr), ret)
return Int(Core.sizeof($rettype))
end
end).args)

# return code to generate wrapper function and send work request thread queue
wrapper = Expr(:var"hygienic-scope", wrapper, @__MODULE__, __source__)
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