%% -*- Erlang -*-
%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2001-2016. All Rights Reserved.
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%% http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%%
%% %CopyrightEnd%
%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%
%% IDENTIFIES THE EXTENDED BASIC BLOCKS OF A CFG
%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-export([cfg/1,
%% dag/2,
type/1,
node_label/1,
node_successors/1
]).
-ifdef(DEBUG_EBB).
-export([pp/1]).
-endif.
-define(cfg, ?CFG).
%%--------------------------------------------------------------------
%% The extended basic block datatype
%%
%% An EBB is identified with the label of the root node.
%% It's a tree
%%
%% EBB := {ebb_node, Label, [EBB]}
%% | {ebb_leaf, SuccesorLabel}
%%--------------------------------------------------------------------
%% XXX: Cheating big time! no recursive types
-type ebb() :: {ebb_node, icode_lbl(), _}
| {ebb_leaf, icode_lbl()}.
-record(ebb_node, {label :: icode_lbl(), successors :: [ebb()]}).
-record(ebb_leaf, {successor :: icode_lbl()}).
%%--------------------------------------------------------------------
%% Returns a list of extended basic blocks.
%%--------------------------------------------------------------------
-spec cfg(cfg()) -> [ebb()].
cfg(CFG) ->
Start = ?cfg:start_label(CFG),
Labels = ?cfg:reverse_postorder(CFG),
Roots = [Start],
Blocks = Labels -- Roots,
Visited = new_visited(),
build_all_ebb(Roots, Blocks, Visited, CFG).
new_visited() ->
gb_sets:empty().
visited(L, Visited) ->
gb_sets:is_member(L, Visited).
visit(L, Visited) ->
gb_sets:add(L, Visited).
build_all_ebb(Roots, Blocks, Visited, CFG) ->
build_all_ebb(Roots, Blocks, Visited, CFG, []).
build_all_ebb([], [], _, _CFG, Ebbs) ->
lists:reverse(Ebbs);
build_all_ebb([], [BlockLeft|BlocksLeft], Visited, CFG, Ebbs) ->
case visited(BlockLeft, Visited) of
true ->
build_all_ebb([], BlocksLeft, Visited, CFG, Ebbs);
false ->
build_all_ebb([BlockLeft], BlocksLeft, Visited, CFG, Ebbs)
end;
build_all_ebb([Root|Roots], Blocks, Visited, CFG, Ebbs) ->
{Ebb, NewVisited} = build_ebb(Root, Visited, CFG),
build_all_ebb(Roots, Blocks, NewVisited, CFG, [Ebb|Ebbs]).
%%
%% Build the extended basic block with Lbl as its root.
%%
build_ebb(Lbl, Visited, CFG) ->
build_ebb(Lbl, Visited,
fun (NodeL, NewVisited) -> {NodeL, NewVisited} end,
[], CFG).
build_ebb(Lbl, Visited, MkFun, EBBs, CFG) ->
Succ = ?cfg:succ(CFG, Lbl),
add_succ(Succ, visit(Lbl, Visited), Lbl, MkFun, EBBs, CFG).
add_succ([], Visited, Node, MkFun, EBBs, _CFG) ->
MkFun(mk_node(Node, lists:reverse(EBBs)), Visited);
add_succ([Lbl|Lbls], Visited, Node, MkFun, EBBs, CFG) ->
case [visited(Lbl, Visited)|?cfg:pred(CFG, Lbl)] of
[false,_] ->
build_ebb(Lbl, Visited,
fun (NewEbb, Visited0) ->
add_succ(Lbls, Visited0, Node, MkFun, [NewEbb|EBBs], CFG)
end, [], CFG);
_ ->
add_succ(Lbls, Visited, Node, MkFun, [mk_leaf(Lbl)|EBBs], CFG)
end.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%
%% Generate a list of dags.
%%
%% dag(EBBs, CFG) ->
%% Start = ?cfg:start_label(CFG),
%% Roots = [Start],
%% Edges = all_adges(EBBs, Roots),
%% start_dag(Roots, Edges, []).
%%
%% start_dag([], _Edges, _Visit) ->
%% [];
%% start_dag([Root|Roots], Edges, Visit) ->
%% case lists:member(Root, Visit) of
%% true ->
%% start_dag(Roots, Edges, Visit);
%% false ->
%% {Dag, Roots0, Visit0} =
%% fill_dag(Root, [Root], Edges, Roots, [Root|Visit]),
%% [lists:reverse(Dag) | start_dag(Roots0, Edges, Visit0)]
%% end.
%%
%% fill_dag(Lbl, Dag, Edges, Roots, Visit) ->
%% Succ = find_succ(Lbl, Edges),
%% add_dag_succ(Succ, Dag, Edges, Roots, Visit).
%%
%% add_dag_succ([], Dag, _Edges, Roots, Visit) ->
%% {Dag, Roots, Visit};
%% add_dag_succ([S|Ss], Dag, Edges, Roots, Visit) ->
%% {Dag0, Roots0, Visit0} = add_dag_succ(Ss, Dag, Edges, Roots, Visit),
%% Pred = find_pred(S, Edges),
%% case all_in(Pred, Dag0) of
%% true ->
%% fill_dag(S, [S|Dag0], Edges, Roots0, [S|Visit0]);
%% false ->
%% {Dag0, [S|Roots], Visit0}
%% end.
%%
%% find_succ(_Lbl, []) ->
%% [];
%% find_succ(Lbl, [{Lbl, Succ}|Edges]) ->
%% [Succ | find_succ(Lbl, Edges)];
%% find_succ(Lbl, [_|Edges]) ->
%% find_succ(Lbl, Edges).
%%
%% find_pred(_Lbl, []) ->
%% [];
%% find_pred(Lbl, [{Pred, Lbl}|Edges]) ->
%% [Pred | find_pred(Lbl, Edges)];
%% find_pred(Lbl, [_|Edges]) ->
%% find_pred(Lbl, Edges).
%%
%% all_edges([], _Roots) ->
%% [];
%% all_edges([EBB|EBBs], Roots) ->
%% succ_edges(node_label(EBB), ebb_successors(EBB), EBBs, Roots).
%%
%% succ_edges(Lbl, [], EBBs, Roots) ->
%% case lists:member(Lbl, Roots) of
%% true ->
%% [{start, Lbl} | all_edges(EBBs, Roots)];
%% false ->
%% all_edges(EBBs, Roots)
%% end;
%% succ_edges(Lbl, [S|Ss], EBBs, Roots) ->
%% [{Lbl, S} | succ_edges(Lbl, Ss, EBBs, Roots)].
%%
%% all_in([], _List) ->
%% true;
%% all_in([X|Xs], List) ->
%% lists:member(X, List) andalso all_in(Xs, List).
%%
%% find_ebb(Lbl, [EBB|EBBs]) ->
%% case node_label(EBB) of
%% Lbl ->
%% EBB;
%% _ ->
%% find_ebb(Lbl, EBBs)
%% end.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-spec mk_node(icode_lbl(), [ebb()]) -> #ebb_node{}.
mk_node(Label, Successors) -> #ebb_node{label=Label, successors=Successors}.
-spec node_label(#ebb_node{}) -> icode_lbl().
node_label(#ebb_node{label=Label}) -> Label.
-spec node_successors(#ebb_node{}) -> [ebb()].
node_successors(#ebb_node{successors=Successors}) -> Successors.
-spec mk_leaf(icode_lbl()) -> #ebb_leaf{}.
mk_leaf(NextEbb) -> #ebb_leaf{successor=NextEbb}.
%% leaf_next(Leaf) -> Leaf#ebb_leaf.successor.
-spec type(#ebb_node{}) -> 'node' ; (#ebb_leaf{}) -> 'leaf'.
type(#ebb_node{}) -> node;
type(#ebb_leaf{}) -> leaf.
%% ebb_successors(EBB) ->
%% ordsets:from_list(ebb_successors0(EBB)).
%%
%% ebb_successors0(#ebb_leaf{successor=NextEBB}) ->
%% [NextEBB];
%% ebb_successors0(#ebb_node{successors=SuccessorNodes}) ->
%% lists:append(lists:map(fun ebb_successors0/1, SuccessorNodes)).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%
%% Prettyprint a list of extended basic blocks
%%
-ifdef(DEBUG_EBB).
pp(EBBs) ->
lists:map(fun(E) -> pp(E, 0) end, EBBs).
pp(EBB, Indent) ->
io:format([$~]++integer_to_list(Indent)++[$c],[$ ]),
case type(EBB) of
node ->
io:format("~w~n", [node_label(EBB)]),
lists:map(fun(E) -> pp(E, Indent+3) end, node_successors(EBB));
leaf ->
io:format("* -> ~w~n", [leaf_next(EBB)])
end.
-endif.
