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-rw-r--r--lib/compiler/src/sys_core_bsm.erl203
-rw-r--r--lib/compiler/test/bs_match_SUITE.erl19
2 files changed, 88 insertions, 134 deletions
diff --git a/lib/compiler/src/sys_core_bsm.erl b/lib/compiler/src/sys_core_bsm.erl
index 37e071fafa..65580f79e3 100644
--- a/lib/compiler/src/sys_core_bsm.erl
+++ b/lib/compiler/src/sys_core_bsm.erl
@@ -24,7 +24,7 @@
-export([module/2,format_error/1]).
-include("core_parse.hrl").
--import(lists, [member/2,nth/2,reverse/1,usort/1]).
+-import(lists, [member/2,reverse/1,usort/1]).
-spec module(cerl:c_module(), [compile:option()]) -> {'ok', cerl:c_module()}.
@@ -59,13 +59,6 @@ format_error(bin_opt_alias) ->
format_error(bin_partition) ->
"INFO: matching non-variables after a previous clause matching a variable "
"will prevent delayed sub binary optimization";
-format_error(bin_left_var_used_in_guard) ->
- "INFO: a variable to the left of the binary pattern is used in a guard; "
- "will prevent delayed sub binary optimization";
-format_error(bin_argument_order) ->
- "INFO: matching anything else but a plain variable to the left of "
- "binary pattern will prevent delayed sub binary optimization; "
- "SUGGEST changing argument order";
format_error(bin_var_used) ->
"INFO: using a matched out sub binary will prevent "
"delayed sub binary optimization";
@@ -96,46 +89,41 @@ bsm_an(#c_case{arg=#c_values{es=Es}}=Case) ->
bsm_an(Other) ->
{ok,Other}.
-bsm_an_1(Vs, #c_case{clauses=Cs}=Case) ->
- case bsm_leftmost(Cs) of
- none -> {ok,Case};
- Pos -> bsm_an_2(Vs, Cs, Case, Pos)
- end.
-
-bsm_an_2(Vs, Cs, Case, Pos) ->
- case bsm_nonempty(Cs, Pos) of
- true -> bsm_an_3(Vs, Cs, Case, Pos);
- false -> {ok,Case}
+bsm_an_1(Vs0, #c_case{clauses=Cs0}=Case) ->
+ case bsm_leftmost(Cs0) of
+ none ->
+ {ok,Case};
+ 1 ->
+ bsm_an_2(Vs0, Cs0, Case);
+ Pos ->
+ Vs = move_from_col(Pos, Vs0),
+ Cs = [C#c_clause{pats=move_from_col(Pos, Ps)} ||
+ #c_clause{pats=Ps}=C <- Cs0],
+ bsm_an_2(Vs, Cs, Case)
end.
-bsm_an_3(Vs, Cs, Case, Pos) ->
+bsm_an_2(Vs, Cs, Case) ->
try
- bsm_ensure_no_partition(Cs, Pos),
- {ok,bsm_do_an(Vs, Pos, Cs, Case)}
+ bsm_ensure_no_partition(Cs),
+ {ok,bsm_do_an(Vs, Cs, Case)}
catch
- throw:{problem,Where,What} ->
- {ok,Case,{Where,What}}
+ throw:{problem,Where,What} ->
+ {ok,Case,{Where,What}}
end.
-bsm_do_an(Vs0, Pos, Cs0, Case) ->
- case nth(Pos, Vs0) of
- #c_var{name=Vname}=V0 ->
- Cs = bsm_do_an_var(Vname, Pos, Cs0, []),
- V = bsm_annotate_for_reuse(V0),
- Bef = lists:sublist(Vs0, Pos-1),
- Aft = lists:nthtail(Pos, Vs0),
- case Bef ++ [V|Aft] of
- [_] ->
- Case#c_case{arg=V,clauses=Cs};
- Vs ->
- Case#c_case{arg=#c_values{es=Vs},clauses=Cs}
- end;
- _ ->
- Case
- end.
+move_from_col(Pos, L) ->
+ {First,[Col|Rest]} = lists:split(Pos - 1, L),
+ [Col|First] ++ Rest.
-bsm_do_an_var(V, S, [#c_clause{pats=Ps,guard=G,body=B0}=C0|Cs], Acc) ->
- case nth(S, Ps) of
+bsm_do_an([#c_var{name=Vname}=V0|Vs0], Cs0, Case) ->
+ Cs = bsm_do_an_var(Vname, Cs0),
+ V = bsm_annotate_for_reuse(V0),
+ Vs = core_lib:make_values([V|Vs0]),
+ Case#c_case{arg=Vs,clauses=Cs};
+bsm_do_an(_Vs, _Cs, Case) -> Case.
+
+bsm_do_an_var(V, [#c_clause{pats=[P|_],guard=G,body=B0}=C0|Cs]) ->
+ case P of
#c_var{name=VarName} ->
case core_lib:is_var_used(V, G) of
true -> bsm_problem(C0, orig_bin_var_used_in_guard);
@@ -148,23 +136,23 @@ bsm_do_an_var(V, S, [#c_clause{pats=Ps,guard=G,body=B0}=C0|Cs], Acc) ->
B1 = bsm_maybe_ctx_to_binary(VarName, B0),
B = bsm_maybe_ctx_to_binary(V, B1),
C = C0#c_clause{body=B},
- bsm_do_an_var(V, S, Cs, [C|Acc]);
- #c_alias{}=P ->
+ [C|bsm_do_an_var(V, Cs)];
+ #c_alias{} ->
case bsm_could_match_binary(P) of
false ->
- bsm_do_an_var(V, S, Cs, [C0|Acc]);
+ [C0|bsm_do_an_var(V, Cs)];
true ->
bsm_problem(C0, bin_opt_alias)
end;
- P ->
+ _ ->
case bsm_could_match_binary(P) andalso bsm_is_var_used(V, G, B0) of
false ->
- bsm_do_an_var(V, S, Cs, [C0|Acc]);
+ [C0|bsm_do_an_var(V, Cs)];
true ->
bsm_problem(C0, bin_var_used)
end
end;
-bsm_do_an_var(_, _, [], Acc) -> reverse(Acc).
+bsm_do_an_var(_, []) -> [].
bsm_annotate_for_reuse(#c_var{anno=Anno}=Var) ->
Var#c_var{anno=[reuse_for_context|Anno]}.
@@ -192,131 +180,82 @@ previous_ctx_to_binary(V, Core) ->
end.
%% bsm_leftmost(Cs) -> none | ArgumentNumber
-%% Find the leftmost argument that does binary matching. Return
-%% the number of the argument (1-N).
+%% Find the leftmost argument that matches a nonempty binary.
+%% Return either 'none' or the argument number (1-N).
bsm_leftmost(Cs) ->
bsm_leftmost_1(Cs, none).
+bsm_leftmost_1([_|_], 1) ->
+ 1;
bsm_leftmost_1([#c_clause{pats=Ps}|Cs], Pos) ->
bsm_leftmost_2(Ps, Cs, 1, Pos);
bsm_leftmost_1([], Pos) -> Pos.
bsm_leftmost_2(_, Cs, Pos, Pos) ->
bsm_leftmost_1(Cs, Pos);
-bsm_leftmost_2([#c_binary{}|_], Cs, N, _) ->
+bsm_leftmost_2([#c_binary{segments=[_|_]}|_], Cs, N, _) ->
bsm_leftmost_1(Cs, N);
bsm_leftmost_2([_|Ps], Cs, N, Pos) ->
bsm_leftmost_2(Ps, Cs, N+1, Pos);
bsm_leftmost_2([], Cs, _, Pos) ->
bsm_leftmost_1(Cs, Pos).
-%% bsm_nonempty(Cs, Pos) -> true|false
-%% Check if at least one of the clauses matches a non-empty
-%% binary in the given argument position.
+%% bsm_ensure_no_partition(Cs) -> ok (exception if problem)
+%% There must only be a single bs_start_match2 instruction if we
+%% are to reuse the binary variable for the match context.
+%%
+%% To make sure that there is only a single bs_start_match2
+%% instruction, we will check for partitions such as:
%%
-bsm_nonempty([#c_clause{pats=Ps}|Cs], Pos) ->
- case nth(Pos, Ps) of
- #c_binary{segments=[_|_]} ->
- true;
- _ ->
- bsm_nonempty(Cs, Pos)
- end;
-bsm_nonempty([], _ ) -> false.
-
-%% bsm_ensure_no_partition(Cs, Pos) -> ok (exception if problem)
-%% We must make sure that matching is not partitioned between
-%% variables like this:
%% foo(<<...>>) -> ...
%% foo(<Variable>) when ... -> ...
-%% foo(<Any non-variable pattern>) ->
-%% If there is such partition, we are not allowed to reuse the binary variable
-%% for the match context.
+%% foo(<Non-variable pattern>) ->
%%
-%% Also, arguments to the left of the argument that is matched
-%% against a binary, are only allowed to be simple variables, not
-%% used in guards. The reason is that we must know that the binary is
-%% only matched in one place (i.e. there must be only one bs_start_match2
-%% instruction emitted).
+%% If there is such partition, we reject the optimization.
-bsm_ensure_no_partition(Cs, Pos) ->
- bsm_ensure_no_partition_1(Cs, Pos, before).
+bsm_ensure_no_partition(Cs) ->
+ bsm_ensure_no_partition_1(Cs, before).
%% Loop through each clause.
-bsm_ensure_no_partition_1([#c_clause{pats=Ps,guard=G}|Cs], Pos, State0) ->
- State = bsm_ensure_no_partition_2(Ps, Pos, G, simple_vars, State0),
+bsm_ensure_no_partition_1([#c_clause{pats=Ps,guard=G}|Cs], State0) ->
+ State = bsm_ensure_no_partition_2(Ps, G, State0),
case State of
'after' ->
- bsm_ensure_no_partition_after(Cs, Pos);
+ bsm_ensure_no_partition_after(Cs);
_ ->
ok
end,
- bsm_ensure_no_partition_1(Cs, Pos, State);
-bsm_ensure_no_partition_1([], _, _) -> ok.
+ bsm_ensure_no_partition_1(Cs, State);
+bsm_ensure_no_partition_1([], _) -> ok.
-%% Loop through each pattern for this clause.
-bsm_ensure_no_partition_2([#c_binary{}=Where|_], 1, _, Vstate, State) ->
- case State of
- before when Vstate =:= simple_vars -> within;
- before -> bsm_problem(Where, Vstate);
- within when Vstate =:= simple_vars -> within;
- within -> bsm_problem(Where, Vstate)
- end;
-bsm_ensure_no_partition_2([#c_alias{}=Alias|_], 1, N, Vstate, State) ->
+bsm_ensure_no_partition_2([#c_binary{}|_], _, _State) ->
+ within;
+bsm_ensure_no_partition_2([#c_alias{}=Alias|_], N, State) ->
%% Retrieve the real pattern that the alias refers to and check that.
P = bsm_real_pattern(Alias),
- bsm_ensure_no_partition_2([P], 1, N, Vstate, State);
-bsm_ensure_no_partition_2([_|_], 1, _, _Vstate, before=State) ->
+ bsm_ensure_no_partition_2([P], N, State);
+bsm_ensure_no_partition_2([_|_], _, before=State) ->
%% No binary matching yet - therefore no partition.
State;
-bsm_ensure_no_partition_2([P|_], 1, _, Vstate, State) ->
+bsm_ensure_no_partition_2([P|_], _, State) ->
case bsm_could_match_binary(P) of
false ->
- %% If clauses can be freely arranged (Vstate =:= simple_vars),
- %% a clause that cannot match a binary will not partition the clause.
- %% Example:
- %%
- %% a(Var, <<>>) -> ...
- %% a(Var, []) -> ...
- %% a(Var, <<B>>) -> ...
- %%
- %% But if the clauses can't be freely rearranged, as in
- %%
- %% b(Var, <<X>>) -> ...
- %% b(1, 2) -> ...
- %%
- %% we do have a problem.
- %%
- case Vstate of
- simple_vars -> State;
- _ -> bsm_problem(P, Vstate)
- end;
+ State;
true ->
%% The pattern P *may* match a binary, so we must update the state.
%% (P must be a variable.)
- case State of
- within -> 'after';
- 'after' -> 'after'
- end
- end;
-bsm_ensure_no_partition_2([#c_var{name=V}|Ps], N, G, Vstate, S) ->
- case core_lib:is_var_used(V, G) of
- false ->
- bsm_ensure_no_partition_2(Ps, N-1, G, Vstate, S);
- true ->
- bsm_ensure_no_partition_2(Ps, N-1, G, bin_left_var_used_in_guard, S)
- end;
-bsm_ensure_no_partition_2([_|Ps], N, G, _, S) ->
- bsm_ensure_no_partition_2(Ps, N-1, G, bin_argument_order, S).
+ 'after'
+ end.
-bsm_ensure_no_partition_after([#c_clause{pats=Ps}=C|Cs], Pos) ->
- case nth(Pos, Ps) of
- #c_var{} ->
- bsm_ensure_no_partition_after(Cs, Pos);
- _ ->
- bsm_problem(C, bin_partition)
+bsm_ensure_no_partition_after([#c_clause{pats=Ps}=C|Cs]) ->
+ case Ps of
+ [#c_var{}|_] ->
+ bsm_ensure_no_partition_after(Cs);
+ _ ->
+ bsm_problem(C, bin_partition)
end;
-bsm_ensure_no_partition_after([], _) -> ok.
+bsm_ensure_no_partition_after([]) -> ok.
bsm_could_match_binary(#c_alias{pat=P}) -> bsm_could_match_binary(P);
bsm_could_match_binary(#c_cons{}) -> false;
diff --git a/lib/compiler/test/bs_match_SUITE.erl b/lib/compiler/test/bs_match_SUITE.erl
index 7557d6d57b..4bd5e8e2e1 100644
--- a/lib/compiler/test/bs_match_SUITE.erl
+++ b/lib/compiler/test/bs_match_SUITE.erl
@@ -40,7 +40,7 @@
map_and_binary/1,unsafe_branch_caching/1,
bad_literals/1,good_literals/1,constant_propagation/1,
parse_xml/1,get_payload/1,escape/1,num_slots_different/1,
- beam_bsm/1,guard/1,is_ascii/1]).
+ beam_bsm/1,guard/1,is_ascii/1,non_opt_eq/1]).
-export([coverage_id/1,coverage_external_ignore/2]).
@@ -73,7 +73,7 @@ groups() ->
map_and_binary,unsafe_branch_caching,
bad_literals,good_literals,constant_propagation,parse_xml,
get_payload,escape,num_slots_different,
- beam_bsm,guard,is_ascii]}].
+ beam_bsm,guard,is_ascii,non_opt_eq]}].
init_per_suite(Config) ->
@@ -1654,6 +1654,21 @@ do_is_ascii(<<C,_/binary>>) when C >= 16#80 ->
do_is_ascii(<<_, T/binary>>) ->
do_is_ascii(T).
+non_opt_eq(_Config) ->
+ true = non_opt_eq([], <<>>),
+ true = non_opt_eq([$a], <<$a>>),
+ false = non_opt_eq([$a], <<$b>>),
+ ok.
+
+%% An example from the Efficiency Guide. It used to be not optimized,
+%% but now it can be optimized.
+
+non_opt_eq([H|T1], <<H,T2/binary>>) ->
+ non_opt_eq(T1, T2);
+non_opt_eq([_|_], <<_,_/binary>>) ->
+ false;
+non_opt_eq([], <<>>) ->
+ true.
check(F, R) ->
R = F().