diff options
Diffstat (limited to 'lib/compiler/src')
| -rw-r--r-- | lib/compiler/src/sys_core_fold.erl | 27 | ||||
| -rw-r--r-- | lib/compiler/src/v3_core.erl | 26 |
2 files changed, 36 insertions, 17 deletions
diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl index 068478496b..6202f07479 100644 --- a/lib/compiler/src/sys_core_fold.erl +++ b/lib/compiler/src/sys_core_fold.erl @@ -1,19 +1,19 @@ %% %% %CopyrightBegin% -%% -%% Copyright Ericsson AB 1999-2009. All Rights Reserved. -%% +%% +%% Copyright Ericsson AB 1999-2010. 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/. -%% +%% %% 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. -%% +%% %% %CopyrightEnd% %% %% Purpose : Constant folding optimisation for Core @@ -602,15 +602,23 @@ count_bits_1(Int, Bits) -> count_bits_1(Int bsr 64, Bits+64). %% a rewritten expression consisting of a sequence of %% the arguments only is returned. -useless_call(effect, #c_call{module=#c_literal{val=Mod}, +useless_call(effect, #c_call{anno=Anno, + module=#c_literal{val=Mod}, name=#c_literal{val=Name}, args=Args}=Call) -> A = length(Args), case erl_bifs:is_safe(Mod, Name, A) of false -> case erl_bifs:is_pure(Mod, Name, A) of - true -> add_warning(Call, result_ignored); - false -> ok + true -> + case member(result_not_wanted, Anno) of + false -> + add_warning(Call, result_ignored); + true -> + ok + end; + false -> + ok end, no; true -> @@ -2806,7 +2814,8 @@ format_error({no_effect,{erlang,F,A}}) -> end, flatten(io_lib:format(Fmt, Args)); format_error(result_ignored) -> - "the result of the expression is ignored"; + "the result of the expression is ignored " + "(suppress the warning by assigning the expression to the _ variable)"; format_error(useless_building) -> "a term is constructed, but never used"; format_error(bin_opt_alias) -> diff --git a/lib/compiler/src/v3_core.erl b/lib/compiler/src/v3_core.erl index 4ac2196d79..b2f0ac75c7 100644 --- a/lib/compiler/src/v3_core.erl +++ b/lib/compiler/src/v3_core.erl @@ -128,6 +128,7 @@ -record(core, {vcount=0 :: non_neg_integer(), %Variable counter fcount=0 :: non_neg_integer(), %Function counter in_guard=false :: boolean(), %In guard or not. + wanted=true :: boolean(), %Result wanted or not. opts :: [compile:option()], %Options. es=[] :: [error()], %Errors. ws=[] :: [warning()], %Warnings. @@ -580,10 +581,14 @@ expr({'fun',L,{function,F,A},{_,_,_}=Id}, St) -> {#c_var{anno=Lanno++[{id,Id}],name={F,A}},[],St}; expr({'fun',L,{clauses,Cs},Id}, St) -> fun_tq(Id, Cs, L, St); -expr({call,L,{remote,_,M,F},As0}, St0) -> +expr({call,L,{remote,_,M,F},As0}, #core{wanted=Wanted}=St0) -> {[M1,F1|As1],Aps,St1} = safe_list([M,F|As0], St0), Lanno = lineno_anno(L, St1), - {#icall{anno=#a{anno=Lanno},module=M1,name=F1,args=As1},Aps,St1}; + Anno = case Wanted of + false -> [result_not_wanted|Lanno]; + true -> Lanno + end, + {#icall{anno=#a{anno=Anno},module=M1,name=F1,args=As1},Aps,St1}; expr({call,Lc,{atom,Lf,F},As0}, St0) -> {As1,Aps,St1} = safe_list(As0, St0), Op = #c_var{anno=lineno_anno(Lf, St1),name={F,length(As1)}}, @@ -596,23 +601,28 @@ expr({call,L,FunExp,As0}, St0) -> expr({match,L,P0,E0}, St0) -> %% First fold matches together to create aliases. {P1,E1} = fold_match(E0, P0), - {E2,Eps,St1} = novars(E1, St0), + St1 = case P1 of + {var,_,'_'} -> St0#core{wanted=false}; + _ -> St0 + end, + {E2,Eps,St2} = novars(E1, St1), + St3 = St2#core{wanted=St0#core.wanted}, P2 = try - pattern(P1, St1) + pattern(P1, St3) catch throw:Thrown -> Thrown end, - {Fpat,St2} = new_var(St1), + {Fpat,St4} = new_var(St3), Fc = fail_clause([Fpat], c_tuple([#c_literal{val=badmatch},Fpat])), - Lanno = lineno_anno(L, St2), + Lanno = lineno_anno(L, St4), case P2 of nomatch -> - St = add_warning(L, nomatch, St2), + St = add_warning(L, nomatch, St4), {#icase{anno=#a{anno=Lanno}, args=[E2],clauses=[],fc=Fc},Eps,St}; Other when not is_atom(Other) -> - {#imatch{anno=#a{anno=Lanno},pat=P2,arg=E2,fc=Fc},Eps,St2} + {#imatch{anno=#a{anno=Lanno},pat=P2,arg=E2,fc=Fc},Eps,St4} end; expr({op,_,'++',{lc,Llc,E,Qs},More}, St0) -> %% Optimise '++' here because of the list comprehension algorithm. |