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%%% -*- erlang-indent-level: 2 -*-
%%%-------------------------------------------------------------------
%%% Author: Kostis Sagonas
%%%
%%% Contains tests that check that tail recursion optimization occurs.
%%%-------------------------------------------------------------------
-module(basic_tail_rec).
-export([test/0]).
-export([app0/2]). %% used in an apply/3 call
test() ->
ok = test_app_tail(),
ok.
%%--------------------------------------------------------------------
%% Written by Mikael Pettersson: check that apply is tail recursive.
%% Increased the following quantity from 20 to 30 so that the test
%% remains valid even with the naive register allocator. - Kostis
-define(SIZE_INCREASE, 30).
test_app_tail() ->
Inc = start(400),
%% io:format("Inc ~w\n", [Inc]),
case Inc > ?SIZE_INCREASE of
true ->
{error, "apply/3 is not tail recursive in native code"};
false ->
ok
end.
start(N) ->
app0(N, hipe_bifs:nstack_used_size()).
app0(0, Size0) ->
hipe_bifs:nstack_used_size() - Size0;
app0(N, Size) ->
apply(?MODULE, app0, [N-1, Size]).
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