From fd9b5ae4193fbab66093c88728c0dbeaa3b57312 Mon Sep 17 00:00:00 2001 From: Hans Bolinder Date: Mon, 27 Aug 2018 13:14:29 +0200 Subject: dialyzer: Improve handling of complex guards See also https://bugs.erlang.org/browse/ERL-680. The right associative short circuit expressions 'andalso' and 'orelse' are expanded by the Compiler (see v3_core) into 'case' expressions. If parentheses are used to enforce left associativeness, variables are introduced, and the time needed by Dialyzer increases exponentially. Rather than trying to fix Dialyzer itself, v3_core now rewrites repeated use of 'andalso' ('orelse') into right associative expressions before creating the 'case' expressions. --- lib/compiler/src/v3_core.erl | 19 ++++- .../test/small_SUITE_data/results/left_assoc | 2 + .../test/small_SUITE_data/src/left_assoc.erl | 96 ++++++++++++++++++++++ 3 files changed, 115 insertions(+), 2 deletions(-) create mode 100644 lib/dialyzer/test/small_SUITE_data/results/left_assoc create mode 100644 lib/dialyzer/test/small_SUITE_data/src/left_assoc.erl diff --git a/lib/compiler/src/v3_core.erl b/lib/compiler/src/v3_core.erl index 3b746ab5bf..c9517c3e51 100644 --- a/lib/compiler/src/v3_core.erl +++ b/lib/compiler/src/v3_core.erl @@ -328,14 +328,16 @@ gexpr({protect,Line,Arg}, Bools0, St0) -> Anno = lineno_anno(Line, St), {#iprotect{anno=#a{anno=Anno},body=Eps++[E]},[],Bools0,St} end; -gexpr({op,L,'andalso',E1,E2}, Bools, St0) -> +gexpr({op,_,'andalso',_,_}=E0, Bools, St0) -> + {op,L,'andalso',E1,E2} = right_assoc(E0, 'andalso', St0), Anno = lineno_anno(L, St0), {#c_var{name=V0},St} = new_var(Anno, St0), V = {var,L,V0}, False = {atom,L,false}, E = make_bool_switch_guard(L, E1, V, E2, False), gexpr(E, Bools, St); -gexpr({op,L,'orelse',E1,E2}, Bools, St0) -> +gexpr({op,_,'orelse',_,_}=E0, Bools, St0) -> + {op,L,'orelse',E1,E2} = right_assoc(E0, 'orelse', St0), Anno = lineno_anno(L, St0), {#c_var{name=V0},St} = new_var(Anno, St0), V = {var,L,V0}, @@ -2054,6 +2056,19 @@ fail_clause(Pats, Anno, Arg) -> body=[#iprimop{anno=#a{anno=Anno},name=#c_literal{val=match_fail}, args=[Arg]}]}. +%% Optimization for Dialyzer. +right_assoc(E, Op, St) -> + case member(dialyzer, St#core.opts) of + true -> + right_assoc2(E, Op); + false -> + E + end. + +right_assoc2({op,L1,Op,{op,L2,Op,E1,E2},E3}, Op) -> + right_assoc2({op,L2,Op,E1,{op,L1,Op,E2,E3}}, Op); +right_assoc2(E, _Op) -> E. + annotate_tuple(A, Es, St) -> case member(dialyzer, St#core.opts) of true -> diff --git a/lib/dialyzer/test/small_SUITE_data/results/left_assoc b/lib/dialyzer/test/small_SUITE_data/results/left_assoc new file mode 100644 index 0000000000..58cdad29de --- /dev/null +++ b/lib/dialyzer/test/small_SUITE_data/results/left_assoc @@ -0,0 +1,2 @@ + +left_assoc.erl:93: The variable __@2 can never match since previous clauses completely covered the type binary() diff --git a/lib/dialyzer/test/small_SUITE_data/src/left_assoc.erl b/lib/dialyzer/test/small_SUITE_data/src/left_assoc.erl new file mode 100644 index 0000000000..0250e4ab49 --- /dev/null +++ b/lib/dialyzer/test/small_SUITE_data/src/left_assoc.erl @@ -0,0 +1,96 @@ +-module(left_assoc). + +%% As pointed out in ERL-680, analyzing guards with short circuit +%% operators becomes very slow as the number of left associations +%% grows. + +-spec from_iso8601('Elixir.String':t(), 'Elixir.Calendar':calendar()) -> + {ok, t()} | {error, atom()}. + +-export_type([t/0]). + +-type t() :: + #{'__struct__' := 'Elixir.Date', + calendar := 'Elixir.Calendar':calendar(), + day := 'Elixir.Calendar':day(), + month := 'Elixir.Calendar':month(), + year := 'Elixir.Calendar':year()}. + +-export([from_iso8601/1, + from_iso8601/2]). + +from_iso8601(__@1) -> + from_iso8601(__@1, 'Elixir.Calendar.ISO'). + +from_iso8601(<<45/integer,_rest@1/binary>>, _calendar@1) -> + case raw_from_iso8601(_rest@1, _calendar@1) of + {ok,#{year := _year@1} = _date@1} -> + {ok,_date@1#{year := - _year@1}}; + __@1 -> + __@1 + end; +from_iso8601(<<_rest@1/binary>>, _calendar@1) -> + raw_from_iso8601(_rest@1, _calendar@1). + +raw_from_iso8601(_string@1, _calendar@1) -> + case _string@1 of + <<_y1@1/integer, + _y2@1/integer, + _y3@1/integer, + _y4@1/integer, + 45/integer, + _m1@1/integer, + _m2@1/integer, + 45/integer, + _d1@1/integer, + _d2@1/integer>> + when + ((((((((((((((_y1@1 >= 48 + andalso + _y1@1 =< 57) + andalso + _y2@1 >= 48) + andalso + _y2@1 =< 57) + andalso + _y3@1 >= 48) + andalso + _y3@1 =< 57) + andalso + _y4@1 >= 48) + andalso + _y4@1 =< 57) + andalso + _m1@1 >= 48) + andalso + _m1@1 =< 57) + andalso + _m2@1 >= 48) + andalso + _m2@1 =< 57) + andalso + _d1@1 >= 48) + andalso + _d1@1 =< 57) + andalso + _d2@1 >= 48) + andalso + _d2@1 =< 57 -> + {ok, + #{year => (_y1@1 - 48) * 1000 + (_y2@1 - 48) * 100 + + + (_y3@1 - 48) * 10 + + + (_y4@1 - 48), + month => (_m1@1 - 48) * 10 + (_m2@1 - 48), + day => (_d1@1 - 48) * 10 + (_d2@1 - 48), + calendar => _calendar@1, + '__struct__' => 'Elixir.Date'}}; + __@1 -> + case __@1 of + _ -> + {error,invalid_format}; + __@2 -> + error({with_clause,__@2}) + end + end. -- cgit v1.2.3