Demangle by default

[brenhinkeller]

So believe it or not this actually doesn't break anything in StaticTools AFAICT, but it'll be breaking for anyone who's using StaticCompiler to compile shlibs that they then call from another language (since then all the function names won't have the extra julia_ added in front)

[MasonProtter]

Wouldnt demangling by default also break functions that call multiple methods from the same function?

i.e.

function f(x::Int)
    y = 1 + x
    return 1.0 + Float64(x)
end

If +’s methods dont get mangled, wouldnt that cause the wrong functions to get called?

[brenhinkeller]

Oh, so this just removes the julia_ that used to get put in front of each method name by GPUCompiler, anything else that happens to the name doesn't get changed..

For that particular example though since there's no dynamic dispatch in the compiled code, the choice of which + function to dispatch though would have been made (and inlined) before we get to compilation

[MasonProtter]

Oh, okay if it just affects the prefix that's fine. The suffixes are important though, even if you don't have dynamic dispatch, just a lack of inlining. See this:

julia> @noinline add(x, y) = x + y;

julia> function f(x::Int)
           y = add(1, x)
           add(1.0, Float64(y))
       end;

julia> code_llvm(f, Tuple{Int})
;  @ REPL[2]:1 within `f`
define double @julia_f_223(i64 signext %0) #0 {
top:
;  @ REPL[2]:2 within `f`
  %1 = call i64 @j_add_225(i64 signext 1, i64 signext %0) #0
;  @ REPL[2]:3 within `f`
; ┌ @ float.jl:159 within `Float64`
   %2 = sitofp i64 %1 to double
; └
  %3 = call double @j_add_226(double 1.000000e+00, double %2) #0
  ret double %3
}

If methods of add got demangled and written out as just add in the LLVM, then the function call in %1 wouldn't be distinct from %3.

So mangling method names is really important.

[brenhinkeller]

Oh yeah, this doesn't mess with the suffixes.. maybe should call it something else but this got introduced a bit back

[MasonProtter]

Yeah, I guess the term is a bit overloaded, but I'd call the prefix thing poor-man's-namespacing, whereas the suffix is true mangling because it's not predictable or stable.