Set a default Clock depending on the grid

[glwagner]

This PR adds a constructor for Clock which depends on grid, and therefore architecture. This allows the clock to be traced when using arch = ReactantState().

In addition to that, this PR discontinues support for run! with arch = ReactantState(). Our rationale is that we cannot yet support the Simulation paradigm, which executes time-steps in a while loop until !(simulation.running), where simulation.running is typically controlled by if statements that depend, for example, on clock.iteration. Basically we're deciding not to try to use @trace if, yet.

As a result, time step loops with Reactant should be managed manually. To facilitate this, this PR also adds a function first_time_step! which first initialize!(model) and update_state!(model) before taking a time-step (which is limited to Euler step for AB2).

cc @giordano

[glwagner]

I believe this is our error now:

Reactant Super Simple Simulation Tests: Error During Test at /Users/gregorywagner/Projects/dev/OC1.jl/test/test_reactant.jl:154
  Got exception outside of a @test
  MethodError: no method matching rem(::Reactant.TracedRNumber{Int64}, ::Int64)

  Closest candidates are:
    rem(::Any, ::Any, ::RoundingMode{:FromZero})
     @ Base div.jl:103
    rem(::Any, ::Any, ::RoundingMode{:Nearest})
     @ Base div.jl:100
    rem(::Any, ::Any, ::RoundingMode{:Up})
     @ Base div.jl:99
    ...

  Stacktrace:
    [1] macro expansion
      @ ~/.julia/packages/Reactant/qEA3Y/src/utils.jl:0 [inlined]
    [2] call_with_reactant(::typeof(rem), ::Reactant.TracedRNumber{Int64}, ::Int64)
      @ Reactant ~/.julia/packages/Reactant/qEA3Y/src/utils.jl:767
    [3] IterationInterval
      @ ~/Projects/dev/OC1.jl/src/Utils/schedules.jl:109 [inlined]

@wsmoses can we add support for rem? If not I think there may be other workarounds.

[glwagner]

@giordano @wsmoses I'm hitting a road block and trying to figure out what is going wrong. I put together a very simple prototype of a function that iterates until a stopping criteria:

using Reactant

mutable struct TestClock{I}
    iteration :: I
end

mutable struct Stopper{I}
    iteration :: I
end

function iterate_until!(clock, stopper)
    iterate = true
    while iterate
        @trace if clock.iteration >= stopper.iteration
            iterate = false
        else
            clock.iteration += 1
        end
    end
    return nothing
end

clock = TestClock(ConcreteRNumber(0))
#stopper = Stopper(ConcreteRNumber(2))
stopper = Stopper(2)

r_iterate! = @compile sync=true iterate_until!(clock, stopper)
r_iterate!(clock, stopper)
@show clock.iteration

This fails with

ERROR: LoadError: TypeError: non-boolean (Reactant.TracedRNumber{Bool}) used in boolean context
Stacktrace:
  [1] macro expansion
    @ ~/.julia/packages/ReactantCore/t40zc/src/ReactantCore.jl:378 [inlined]
  [2] iterate_until!
    @ ~/Projects/Oceananigans.jl/test/test_reactant.jl:31 [inlined]
  [3] iterate_until!(none::TestClock{Reactant.TracedRNumber{Int64}}, none::Stopper{Int64})
    @ Reactant ./<missing>:0
  [4] iterate_until!
    @ ~/Projects/Oceananigans.jl/test/test_reactant.jl:30 [inlined]

where line 31 is @trace if clock.iteration >= stopper.iteration.

I'm also wondering whether the stopper.iteration needs to be traced, or not?

I think getting this prototype to work will show me how to get this PR merged

[glwagner]

Couple issues open to work on stuff that's come up:

• Unexpected non-boolean (Reactant.TracedRNumber{Bool}) used in boolean context EnzymeAD/Reactant.jl#793
• Error when trying to show an error EnzymeAD/Reactant.jl#792

[glwagner]

@giordano I think we've made progress on this and now run! actually "starts to" compile. However, it takes a long time. In fact it is still going

[glwagner]

Note running the tests requires adding TestEnv to your global environment and then

using TestEnv; TestEnv.activate()
using Pkg; Pkg.add("Reactant", rev="glw-wm/traced-set-path")
include("test/test_reactant.jl")

[glwagner]

This is ready and tests will hopefully pass soon @wsmoses @simone-silvestri @giordano . I've updated the top post to describe what we've done.