Test no allocations in tests

Author: blegat

src/Nonlinear/ReverseAD/forward_over_reverse.jl

@@ -6,11 +6,13 @@
 
 const TAG = :ReverseAD
 
+const MAX_CHUNK = 10
+
 function _generate_eval_hessian()
-    exprs = map(1:10) do chunk
+    exprs = map(1:MAX_CHUNK) do chunk
         return :(return _eval_hessian_inner(d, f, H, λ, offset, Val($chunk)))
     end
-    return Nonlinear._create_binary_switch(1:10, exprs)
+    return Nonlinear._create_binary_switch(1:MAX_CHUNK, exprs)
 end
 
 @eval begin

src/Nonlinear/ReverseAD/mathoptinterface_api.jl

@@ -140,8 +140,7 @@ function MOI.initialize(d::NLPEvaluator, requested_features::Vector{Symbol})
         max_expr_length = max(max_expr_length, length(d.constraints[end].nodes))
         max_chunk = max(max_chunk, size(d.constraints[end].seed_matrix, 2))
     end
-    # 10 is hardcoded upper bound to avoid excess memory allocation
-    max_chunk = min(max_chunk, 10)
+    max_chunk = min(max_chunk, MAX_CHUNK)
     max_expr_with_sub_length = max(max_expr_with_sub_length, max_expr_length)
     if d.want_hess || want_hess_storage
         d.input_ϵ = zeros(max_chunk * N)

test/Nonlinear/ReverseAD.jl

@@ -150,16 +150,7 @@ function test_objective_quadratic_multivariate_subexpressions()
     MOI.eval_hessian_objective(evaluator, H, val)
     @test H == [2.0, 2.0, 1.0]
     @test evaluator.backend.max_chunk == 2
-    # The call of `_eval_hessian_inner` from `_eval_hessian` needs dynamic dispatch for `Val(chunk)` so it allocates.
-    # We call directly `_eval_hessian_inner` to check that the rest does not allocates.
-    @test 0 == @allocated MOI.Nonlinear.ReverseAD._eval_hessian_inner(
-        evaluator.backend,
-        evaluator.backend.objective,
-        H,
-        1.0,
-        0,
-        Val(2),
-    )
+    @test 0 == @allocated MOI.eval_hessian_objective(evaluator, H, val)
     @test MOI.hessian_lagrangian_structure(evaluator) ==
           [(1, 1), (2, 2), (2, 1)]
     H = [NaN, NaN, NaN]