diff options
Diffstat (limited to 'lib/compiler/src/beam_peep.erl')
| -rw-r--r-- | lib/compiler/src/beam_peep.erl | 83 |
1 files changed, 42 insertions, 41 deletions
diff --git a/lib/compiler/src/beam_peep.erl b/lib/compiler/src/beam_peep.erl index 97a8c7ba70..c8bef31824 100644 --- a/lib/compiler/src/beam_peep.erl +++ b/lib/compiler/src/beam_peep.erl @@ -1,18 +1,19 @@ %% %% %CopyrightBegin% %% -%% Copyright Ericsson AB 2008-2013. All Rights Reserved. +%% Copyright Ericsson AB 2008-2016. All Rights Reserved. %% -%% The contents of this file are subject to the Erlang Public License, -%% Version 1.1, (the "License"); you may not use this file except in -%% compliance with the License. You should have received a copy of the -%% Erlang Public License along with this software. If not, it can be -%% retrieved online at http://www.erlang.org/. +%% 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 %% -%% Software distributed under the License is distributed on an "AS IS" -%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See -%% the License for the specific language governing rights and limitations -%% under the License. +%% 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% %% @@ -64,18 +65,6 @@ function({function,Name,Arity,CLabel,Is0}) -> %% InEncoding =:= latin1, OutEncoding =:= unicode; %% InEncoding =:= latin1, OutEncoding =:= utf8 -> %% -%% (2) A select_val/4 instruction that only verifies that -%% its argument is either 'true' or 'false' can be -%% be replaced with an is_boolean/2 instruction. That is: -%% -%% select_val Reg Fail [ true Next false Next ] -%% Next: ... -%% -%% can be rewritten to -%% -%% is_boolean Fail Reg -%% Next: ... -%% peep(Is) -> peep(Is, gb_sets:empty(), []). @@ -94,12 +83,19 @@ peep([{gc_bif,_,_,_,_,Dst}=I|Is], SeenTests0, Acc) -> %% Kill all remembered tests that depend on the destination register. SeenTests = kill_seen(Dst, SeenTests0), peep(Is, SeenTests, [I|Acc]); -peep([{test,is_boolean,{f,Fail},Ops}|_]=Is, SeenTests, - [{test,is_atom,{f,Fail},Ops}|Acc]) -> - %% The previous is_atom/2 test (with the same failure label) is redundant. - %% (If is_boolean(Src) is true, is_atom(Src) is also true, so it is - %% OK to still remember that we have seen is_atom/1.) - peep(Is, SeenTests, Acc); +peep([{jump,{f,L}},{label,L}=I|Is], _, Acc) -> + %% Sometimes beam_jump has missed this optimization. + peep(Is, gb_sets:empty(), [I|Acc]); +peep([{select,Op,R,F,Vls0}|Is], _, Acc) -> + case prune_redundant_values(Vls0, F) of + [] -> + %% No values left. Must convert to plain jump. + I = {jump,F}, + peep(Is, gb_sets:empty(), [I|Acc]); + [_|_]=Vls -> + I = {select,Op,R,F,Vls}, + peep(Is, gb_sets:empty(), [I|Acc]) + end; peep([{test,Op,_,Ops}=I|Is], SeenTests0, Acc) -> case beam_utils:is_pure_test(I) of false -> @@ -108,34 +104,33 @@ peep([{test,Op,_,Ops}=I|Is], SeenTests0, Acc) -> %% has succeeded. peep(Is, gb_sets:empty(), [I|Acc]); true -> - Test = {Op,Ops}, - case gb_sets:is_element(Test, SeenTests0) of + case is_test_redundant(Op, Ops, SeenTests0) of true -> - %% This test has already succeeded and + %% This test or a similar test has already succeeded and %% is therefore redundant. peep(Is, SeenTests0, Acc); false -> %% Remember that we have seen this test. + Test = {Op,Ops}, SeenTests = gb_sets:insert(Test, SeenTests0), peep(Is, SeenTests, [I|Acc]) end end; -peep([{select,select_val,Src,Fail, - [{atom,false},{f,L},{atom,true},{f,L}]}| - [{label,L}|_]=Is], SeenTests, Acc) -> - I = {test,is_boolean,Fail,[Src]}, - peep([I|Is], SeenTests, Acc); -peep([{select,select_val,Src,Fail, - [{atom,true},{f,L},{atom,false},{f,L}]}| - [{label,L}|_]=Is], SeenTests, Acc) -> - I = {test,is_boolean,Fail,[Src]}, - peep([I|Is], SeenTests, Acc); peep([I|Is], _, Acc) -> %% An unknown instruction. Throw away all information we %% have collected about test instructions. peep(Is, gb_sets:empty(), [I|Acc]); peep([], _, Acc) -> reverse(Acc). +is_test_redundant(Op, Ops, Seen) -> + gb_sets:is_element({Op,Ops}, Seen) orelse + is_test_redundant_1(Op, Ops, Seen). + +is_test_redundant_1(is_boolean, [R], Seen) -> + gb_sets:is_element({is_eq_exact,[R,{atom,false}]}, Seen) orelse + gb_sets:is_element({is_eq_exact,[R,{atom,true}]}, Seen); +is_test_redundant_1(_, _, _) -> false. + kill_seen(Dst, Seen0) -> gb_sets:from_ordset(kill_seen_1(gb_sets:to_list(Seen0), Dst)). @@ -145,3 +140,9 @@ kill_seen_1([{_,Ops}=Test|T], Dst) -> false -> [Test|kill_seen_1(T, Dst)] end; kill_seen_1([], _) -> []. + +prune_redundant_values([_Val,F|Vls], F) -> + prune_redundant_values(Vls, F); +prune_redundant_values([Val,Lbl|Vls], F) -> + [Val,Lbl|prune_redundant_values(Vls, F)]; +prune_redundant_values([], _) -> []. |