`Builder` incorrectly inserts global values into IR

[MasonProtter]

Ran into this today:

julia> using CodeInfoTools

julia> x = 1 #global variable
1

julia> f(y) = x + y;

julia> code_info(f, Int)
CodeInfo(
1 ─ %1 = Main.x + y
└──      return %1
)

julia> for (v, st) ∈ Builder(ans)
           @show st
       end
st = :((+)(1, _2))
st = :(return %1)

Here, we can see that the global variable x's value got embedded directly into the IR from the Builder, rather than a reference to it. This can cause subtle and hard to track down errors in code generated with Builder.

IMO x and + should both be GlobalRefs here.

julia> let b = Builder(code_info(f, Int))
           for (v, st) ∈ b
               b[v] = b[v]
           end
           finish(b)
       end
CodeInfo(
    @ REPL[8]:1 within `f`
1 ─ %1 = (+)(1, y)
└──      return %1
)

[femtomc]

I think this is due to the resolve style pass on GlobalRef.

This pass is responsible for converting GlobalRef references for functions into their values.

I'm fine taking this pass out, and deferring to a user if they want to do this sort of resolution.

[femtomc]

Ref:

CodeInfoTools.jl/src/CodeInfoTools.jl

Lines 121 to 122 in d838a72

	resolve(x) = x
	resolve(gr::GlobalRef) = getproperty(gr.mod, gr.name)