C Global Structs

[Steve Kelly]

I'd like to see if Julia is running in code-coverage mode or not.

In the REPL I can do the following:

julia> a = cglobal(:(jl_compileropts))
Ptr{Void} @0x00007fa3e01bbc90

The struct is defined like so:
https://github.com/JuliaLang/julia/blob/aab2c6e67b5aaee7f23bc5a52897f7219473c153/src/julia.h#L1330-L1338

How can I access the code_coverage member?

Thanks,

Steve

[Isaiah Norton]

julia> immutable JCopt
           build_path::Ptr{Uint8}
           cc::Int8
           ml::Int8
           cb::Int8
           dbc::Int8
           il::Cint
           ce::Int8
       end

julia>  a = cglobal(:(jl_compileropts))

Ptr{Void} @0x000000006d7daf90

julia> unsafe_load(reinterpret(Ptr{JCopt}, a))
JCopt(Ptr{Uint8} @0x0000000000000000,1,0,0,0,0,16)

[Jake Bolewski]

julia> immutable CompilerOpts

       build_path::Ptr{Cchar}

       code_coverage::Int8

       malloc_log::Int8

       check_bounds::Int8

       dumpbitcode::Int8

       int_literals::Cint

       compile_enabled::Int8

       end

julia> a = cglobal(:jl_compileropts, CompilerOpts)

Ptr{CompilerOpts} @0x000000010f840a88

julia> unsafe_load(a)

CompilerOpts(Ptr{Int8} @0x0000000000000000,0,0,0,0,0,1)

[Steve Kelly]

This works excellent, thank you both!

Do you think this would be useful to have these user-facing in Base?

[Isaiah Norton]

I'm not sure; what do you want to do with this? It seems kind of devious to me to change the runtime behavior based on whether coverage is enabled :)

[Steve Kelly]

I am working on local code coverage analysis for Coverage.jl. I want to warn the user if tests are being run without --code-coverage.

By user facing, I mean the ability to read them as Bools, similar to the isinteractive() method. I am going to implemented this in Coverage.jl for 0.3, but If the struct changes in 0.4 this will double the code. I will file an issue to get a discussion started.