Subverting type inference?

[timholy]

I'm trying some dirty tricks and getting crashes. Here the goal is to measure how much time inference spends on each function: my thought was I could define

const __inf_timing__ = Tuple{Float64,Core.MethodInstance}[]

function typeinf_ext_timed(linfo::Core.MethodInstance, params::Core.Compiler.Params)
    tstart = ccall(:jl_clock_now, Float64, ())
    ret = Core.Compiler.typeinf_ext(linfo, params)
    tstop = ccall(:jl_clock_now, Float64, ())
    push!(__inf_timing__, (tstop-tstart, linfo))
    return ret
end

and then be really sneaky and swap this in place of typeinf_ext:

macro snoopi(args...)
    # some preparatory work
    quote
        empty!($__inf_timing__)
        ccall(:jl_set_typeinf_func, Cvoid, (Any,), $typeinf_ext_timed)
        try
            $(esc(cmd))
        finally
            ccall(:jl_set_typeinf_func, Cvoid, (Any,), Core.Compiler.typeinf_ext)
        end
        $sort_timed_inf($tmin)
    end
end

Even though I make sure typeinf_ext_timed is compiled before it gets called, I get a crash when I first switch to it:

Internal error: encountered unexpected error in runtime:
MethodError(f=typeof(SnoopCompile.typeinf_ext_timed)(), args=((::Type{BoundsError})(Any, Tuple{Base.IteratorsMD.CartesianIndex{0}}), 0x00000000000063e2), world=0x00000000000063e1)
rec_backtrace at /home/tim/src/julia-1/src/stackwalk.c:94
record_backtrace at /home/tim/src/julia-1/src/task.c:217 [inlined]
jl_throw at /home/tim/src/julia-1/src/task.c:417
jl_method_error_bare at /home/tim/src/julia-1/src/gf.c:1649
jl_method_error at /home/tim/src/julia-1/src/gf.c:1667
jl_apply_generic at /home/tim/src/julia-1/src/gf.c:2195
jl_apply at /home/tim/src/julia-1/src/julia.h:1571 [inlined]
jl_type_infer at /home/tim/src/julia-1/src/gf.c:277
jl_set_typeinf_func at /home/tim/src/julia-1/src/gf.c:558
top-level scope at /home/tim/.julia/dev/SnoopCompile/src/SnoopCompile.jl:52
jl_fptr_trampoline at /home/tim/src/julia-1/src/gf.c:1864
jl_toplevel_eval_flex at /home/tim/src/julia-1/src/toplevel.c:758
jl_parse_eval_all at /home/tim/src/julia-1/src/ast.c:883
jl_load at /home/tim/src/julia-1/src/toplevel.c:826
include at ./boot.jl:326 [inlined]
include_relative at ./loading.jl:1038
include at ./sysimg.jl:29
jl_apply_generic at /home/tim/src/julia-1/src/gf.c:2219
exec_options at ./client.jl:267
_start at ./client.jl:436
jl_apply_generic at /home/tim/src/julia-1/src/gf.c:2219
jl_apply at /home/tim/src/julia-1/ui/../src/julia.h:1571 [inlined]
true_main at /home/tim/src/julia-1/ui/repl.c:96
main at /home/tim/src/julia-1/ui/repl.c:217
__libc_start_main at /build/glibc-OTsEL5/glibc-2.27/csu/../csu/libc-start.c:310
_start at /home/tim/src/julia-1/julia (unknown line)
Internal error: encountered unexpected error in runtime:
MethodError(f=typeof(SnoopCompile.typeinf_ext_timed)(), args=((::Type{BoundsError})(Any, Base.LinearIndices{1, Tuple{Base.OneTo{Int64}}}), 0x00000000000063e2), world=0x00000000000063e1)
...

This happens independently of whether I try to be really sneaky and set the min_world on the specialization of typeinf_ext_timed to 0.

Is there a workaround? Another (potentially important) application for this general idea is JuliaDebug/JuliaInterpreter.jl#204.