@wsmoses is encountering embedded null pointers in IR emitted during precompilation.
The root cause for this is that we have a control flag .imaging that controls if we are emitting IR for JIT (with embedded pointers) or IR for caching with relocation.
https://github.com/JuliaLang/julia/blob/21eadc5e3129a557df1eb385113132a97996af5e/src/aotcompile.cpp#L342
That flag is either set as an argument by us (which we never turned on #125 #348) or calculated based on the startup flags of Julia
https://github.com/JuliaLang/julia/blob/21eadc5e3129a557df1eb385113132a97996af5e/src/jitlayers.h#L77-L78
This didn't show up before since outside precompilation imaging_default() returns false.
Likely the best way would be to follow the pattern we have for 1.13 and above
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# Since Julia 1.13, the caller is responsible for initializing global variables that |
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# point to global values or bindings with their address in memory. |
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num_gvars = Ref{Csize_t}(0) |
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@ccall jl_get_llvm_gvs(native_code::Ptr{Cvoid}, num_gvars::Ptr{Csize_t}, |
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C_NULL::Ptr{Cvoid})::Nothing |
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gvs = Vector{Ptr{LLVM.API.LLVMOpaqueValue}}(undef, num_gvars[]) |
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@ccall jl_get_llvm_gvs(native_code::Ptr{Cvoid}, num_gvars::Ptr{Csize_t}, |
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gvs::Ptr{LLVM.API.LLVMOpaqueValue})::Nothing |
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inits = Vector{Ptr{Cvoid}}(undef, num_gvars[]) |
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@ccall jl_get_llvm_gv_inits(native_code::Ptr{Cvoid}, num_gvars::Ptr{Csize_t}, |
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inits::Ptr{Cvoid})::Nothing |
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|
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for (gv_ref, init) in zip(gvs, inits) |
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gv = GlobalVariable(gv_ref) |
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val = const_inttoptr(ConstantInt(Int64(init)), LLVM.PointerType()) |
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initializer!(gv, val) |
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end |
which makes the handling of global values consistent
#752 is an attempt to do that by looking at the table of global values, but we lack the infrastructure to access all the information needed.
