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-rw-r--r--lib/compiler/src/beam_record.erl126
1 files changed, 76 insertions, 50 deletions
diff --git a/lib/compiler/src/beam_record.erl b/lib/compiler/src/beam_record.erl
index 419089b1bc..cfad773fa4 100644
--- a/lib/compiler/src/beam_record.erl
+++ b/lib/compiler/src/beam_record.erl
@@ -15,19 +15,12 @@
%%
%% %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:
+%% Tagged tuples means a tuple of any arity with an atom as its
+%% first element, such as records and error tuples.
+%%
+%% From:
%% ...
%% {test,is_tuple,Fail,[Src]}.
%% {test,test_arity,Fail,[Src,Sz]}.
@@ -36,13 +29,16 @@
%% ...
%% {test,is_eq_exact,Fail,[Dst,Atom]}.
%% ...
-%% to:
+%% To:
%% ...
%% {test,is_tagged_tuple,Fail,[Src,Sz,Atom]}.
%% ...
+%%
+-module(beam_record).
+-export([module/2]).
--import(lists, [reverse/1]).
+-import(lists, [reverse/1,reverse/2]).
-spec module(beam_utils:module_code(), [compile:option()]) ->
{'ok',beam_utils:module_code()}.
@@ -51,10 +47,12 @@ module({Mod,Exp,Attr,Fs0,Lc}, _Opt) ->
Fs = [function(F) || F <- Fs0],
{ok,{Mod,Exp,Attr,Fs,Lc}}.
-function({function,Name,Arity,CLabel,Is}) ->
+function({function,Name,Arity,CLabel,Is0}) ->
try
- Idx = beam_utils:index_labels(Is),
- {function,Name,Arity,CLabel,rewrite(Is,Idx)}
+ Is1 = beam_utils:anno_defs(Is0),
+ Idx = beam_utils:index_labels(Is1),
+ Is = rewrite(reverse(Is1), Idx),
+ {function,Name,Arity,CLabel,Is}
catch
Class:Error ->
Stack = erlang:get_stacktrace(),
@@ -62,45 +60,73 @@ function({function,Name,Arity,CLabel,Is}) ->
erlang:raise(Class, Error, Stack)
end.
-rewrite(Is,Idx) ->
- rewrite(Is,Idx,[]).
+rewrite(Is, Idx) ->
+ rewrite(Is, Idx, 0, []).
-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
+rewrite([{test,test_arity,Fail,[Src,N]}=TA,
+ {test,is_tuple,Fail,[Src]}=TT|Is], Idx, Def, Acc0) ->
+ case is_tagged_tuple(Acc0, Def, 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])
+ rewrite(Is, Idx, 0, [TT,TA|Acc0]);
+ {yes,Atom,Acc} ->
+ I = {test,is_tagged_tuple,Fail,[Src,N,Atom]},
+ rewrite(Is, Idx, Def, [I|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) ->
+rewrite([{block,[{'%def',Def}|Bl]}|Is], Idx, _Def, Acc) ->
+ rewrite(Is, Idx, Def, [{block,Bl}|Acc]);
+rewrite([{label,L}=I|Is], Idx0, Def, Acc) ->
+ Idx = beam_utils:index_label(L, Acc, Idx0),
+ rewrite(Is, Idx, Def, [I|Acc]);
+rewrite([I|Is], Idx, Def, Acc) ->
+ rewrite(Is, Idx, Def, [I|Acc]);
+rewrite([], _, _, Acc) -> Acc.
- %% 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]}
+is_tagged_tuple([{block,Bl},
+ {test,is_eq_exact,Fail,[Dst,{atom,_}=Atom]}|Is],
+ Def, Fail, Src, Idx) ->
+ case is_tagged_tuple_1(Bl, Is, Fail, Src, Dst, Idx, Def, []) of
+ no ->
+ no;
+ {yes,[]} ->
+ {yes,Atom,Is};
+ {yes,[_|_]=Block} ->
+ {yes,Atom,[{block,Block}|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
+is_tagged_tuple(_, _, _, _, _) ->
+ no.
+
+is_tagged_tuple_1([{set,[Dst],[Src],{get_tuple_element,0}}=I|Bl],
+ Is, Fail, Src, Dst, Idx, Def, Acc) ->
+ %% Check usage of Dst to find out whether the get_tuple_element
+ %% is needed.
+ case usage(Dst, Is, Fail, Idx) of
+ killed ->
+ %% Safe to remove the get_tuple_element instruction.
+ {yes,reverse(Acc, Bl)};
+ used ->
+ %% Actively used. Must keep instruction.
+ {yes,reverse(Acc, [I|Bl])};
+ not_used ->
+ %% Not actually used (but must be initialized).
+ case is_defined(Dst, Def) of
+ false ->
+ %% Dst must be initialized, but the
+ %% actual value does not matter.
+ Kill = {set,[Dst],[nil],move},
+ {yes,reverse(Acc, [Kill|Bl])};
+ true ->
+ %% The register is previously initialized.
+ %% We can remove the instruction.
+ {yes,reverse(Acc, Bl)}
+ end
end;
-is_tagged_tuple(_Is,_Fail,_Src,_Idx) ->
+is_tagged_tuple_1([I|Bl], Is, Fail, Src, Dst, Idx, Def, Acc) ->
+ is_tagged_tuple_1(Bl, Is, Fail, Src, Dst, Idx, Def, [I|Acc]);
+is_tagged_tuple_1(_, _, _, _, _, _, _, _) ->
no.
-is_killed(Dst,Is,{_,Lbl},Idx) ->
- beam_utils:is_killed(Dst,Is,Idx) andalso
- beam_utils:is_killed_at(Dst,Lbl,Idx).
+usage(Dst, Is, Fail, Idx) ->
+ beam_utils:usage(Dst, [{test,is_number,Fail,[nil]}|Is], Idx).
+
+is_defined({x,X}, Def) ->
+ (Def bsr X) band 1 =:= 1.