Code to read the `jl_compileropts` structure in julia at runtime

.juliarc.jl

#!/usr/bin/env julia

immutable jl_compileropts
	build_path::ASCIIString
	cpu_target::ASCIIString
	code_coverage::Int8
	check_bounds::Int8
	int_literals::Int32
end

function load_compileropts()
	opts_addr = cglobal(:jl_compileropts)

	build_path = unsafe_load(convert(Ptr{Ptr{Uint8}}, opts_addr))
	if build_path != C_NULL
		build_path = bytestring(build_path)
	else
		build_path = ""
	end
	opts_addr += sizeof(Ptr{Uint8})

	cpu_target = unsafe_load(convert(Ptr{Ptr{Uint8}}, opts_addr))
	if cpu_target != C_NULL
		cpu_target = bytestring(cpu_target)
	else
		cpu_target = ""
	end
	opts_addr += sizeof(Ptr{Uint8})

	code_coverage = unsafe_load(convert(Ptr{Int8}, opts_addr))
	opts_addr += sizeof(Int8)

	check_bounds = unsafe_load(convert(Ptr{Int8}, opts_addr))
	opts_addr += sizeof(Int8)

	int_literals = unsafe_load(convert(Ptr{Int32}, opts_addr))
	opts_addr += sizeof(Int32)

	return jl_compileropts(build_path, cpu_target, code_coverage, check_bounds, int_literals)
end

println("cpu_target: $(load_compileropts().cpu_target)")

Unless you declared this struct as __attribute__((packed)) in C, opts_addr has the wrong offset for int_literals. In general, it is better to declare the entire struct in Julia and load it in one go:

immutable jl_compileropts
    build_path::Ptr{Uint8}
    cpu_target::Ptr{Uint8}
    code_coverage::Int8
    check_bounds::Int8
    int_literals::Int32
end
function load_compileropts()
    return unsafe_load(cglobal(:jl_compileropts, jl_compileropts))
end