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-rw-r--r--lib/compiler/src/beam_peep.erl49
1 files changed, 20 insertions, 29 deletions
diff --git a/lib/compiler/src/beam_peep.erl b/lib/compiler/src/beam_peep.erl
index 17fd2e502a..c8bef31824 100644
--- a/lib/compiler/src/beam_peep.erl
+++ b/lib/compiler/src/beam_peep.erl
@@ -1,7 +1,7 @@
%%
%% %CopyrightBegin%
%%
-%% Copyright Ericsson AB 2008-2013. All Rights Reserved.
+%% Copyright Ericsson AB 2008-2016. All Rights Reserved.
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
@@ -65,18 +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(), []).
@@ -95,12 +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 ->
@@ -121,16 +116,6 @@ peep([{test,Op,_,Ops}=I|Is], SeenTests0, Acc) ->
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.
@@ -155,3 +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([], _) -> [].