Question regarding Base.power_by_squaring

New to Julia
3

This seems to be a limitation of the @code_… macros. If you look at the corresponding function e.g.:

help?> code_lowered
search: code_lowered @code_lowered

  code_lowered(f, types; generated=true, debuginfo=:default)
  ...

you see, that it is working only on the types, e.g.:

ulia> code_lowered( ^, (Int,Int) )
1-element Vector{Core.CodeInfo}:
 CodeInfo(
1 ─ %1 = Base.power_by_squaring(x, p)
└──      return %1
)

therefor you get the the wrong implementation. You can overcome this by:

julia> function show_power()
       res=^(2,-5)
       end
show_power (generic function with 1 method)

julia> @code_lowered show_power()
CodeInfo(
1 ─ %1 = Core.apply_type(Base.Val, -5)
│   %2 = (%1)()
│   %3 = Base.literal_pow(Main.:^, 2, %2)
│        res = %3
└──      return %3
)

You see now that Base.literal_pow is actually called.

(expanded on @sgaure answer)

2 Likes