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%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2014-2017. 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%
%%
%% File: beam_record.erl
%% Author: Björn-Egil Dahlberg
%% Created: 2014-09-03
%%
-module(beam_record).
-export([module/2]).
%% Rewrite the instruction stream on tagged tuple tests.
%% Tagged tuples means a tuple of any arity with an atom as its first element.
%% Typically records, ok-tuples and error-tuples.
%%
%% from:
%% ...
%% {test,is_tuple,Fail,[Src]}.
%% {test,test_arity,Fail,[Src,Sz]}.
%% ...
%% {get_tuple_element,Src,0,Dst}.
%% ...
%% {test,is_eq_exact,Fail,[Dst,Atom]}.
%% ...
%% to:
%% ...
%% {test,is_tagged_tuple,Fail,[Src,Sz,Atom]}.
%% ...
-import(lists, [reverse/1]).
-spec module(beam_utils:module_code(), [compile:option()]) ->
{'ok',beam_utils:module_code()}.
module({Mod,Exp,Attr,Fs0,Lc}, _Opt) ->
Fs = [function(F) || F <- Fs0],
{ok,{Mod,Exp,Attr,Fs,Lc}}.
function({function,Name,Arity,CLabel,Is}) ->
try
Idx = beam_utils:index_labels(Is),
{function,Name,Arity,CLabel,rewrite(Is,Idx)}
catch
Class:Error ->
Stack = erlang:get_stacktrace(),
io:fwrite("Function: ~w/~w\n", [Name,Arity]),
erlang:raise(Class, Error, Stack)
end.
rewrite(Is,Idx) ->
rewrite(Is,Idx,[]).
rewrite([{test,is_tuple,Fail,[Src]}=I1,
{test,test_arity,Fail,[Src,N]}=I2|Is],Idx,Acc) ->
case is_tagged_tuple(Is,Fail,Src,Idx) of
no ->
rewrite(Is,Idx,[I2,I1|Acc]);
{Atom,[{block,[]}|Is1]} ->
rewrite(Is1,Idx,[{test,is_tagged_tuple,Fail,[Src,N,Atom]}|Acc]);
{Atom,Is1} ->
rewrite(Is1,Idx,[{test,is_tagged_tuple,Fail,[Src,N,Atom]}|Acc])
end;
rewrite([I|Is],Idx,Acc) ->
rewrite(Is,Idx,[I|Acc]);
rewrite([],_,Acc) -> reverse(Acc).
is_tagged_tuple([{block,[{set,[Dst],[Src],{get_tuple_element,0}}=B|Bs]},
{test,is_eq_exact,Fail,[Dst,{atom,_}=Atom]}|Is],Fail,Src,Idx) ->
%% if Dst is killed in the instruction stream and at fail label,
%% we can safely remove get_tuple_element.
%%
%% if Dst is not killed in the stream, we cannot remove get_tuple_element
%% since it is referenced.
case is_killed(Dst,Is,Fail,Idx) of
true -> {Atom,[{block,Bs}|Is]};
false -> {Atom,[{block,[B|Bs]}|Is]}
end;
is_tagged_tuple([{block,[{set,_,_,_}=B|Bs]},
{test,is_eq_exact,_,_}=I|Is],Fail,Src,Idx) ->
case is_tagged_tuple([{block,Bs},I|Is],Fail,Src,Idx) of
{Atom,[{block,Bsr}|Isr]} -> {Atom,[{block,[B|Bsr]}|Isr]};
no -> no
end;
is_tagged_tuple(_Is,_Fail,_Src,_Idx) ->
no.
is_killed(Dst,Is,{_,Lbl},Idx) ->
beam_utils:is_killed(Dst,Is,Idx) andalso
beam_utils:is_killed_at(Dst,Lbl,Idx).
|
