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authorBjörn Gustavsson <[email protected]>2015-08-10 14:27:50 +0200
committerBjörn Gustavsson <[email protected]>2015-08-21 15:56:14 +0200
commitf63b503f9c7ea4d5824899dc5b287075e261e6a8 (patch)
treebc2fa8d75365baee1dca18ec72984aeee2c2a821 /lib/compiler
parent30cc5c902d9e653d48452a7f84fcd664cfc3f0a8 (diff)
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Move rewriting of select_val to is_boolean from beam_peep to beam_dead
We can rewrite more instances of select_val to is_boolean because it is not necessary that a particular label follows the select_val.
Diffstat (limited to 'lib/compiler')
-rw-r--r--lib/compiler/src/beam_dead.erl24
-rw-r--r--lib/compiler/src/beam_peep.erl28
2 files changed, 21 insertions, 31 deletions
diff --git a/lib/compiler/src/beam_dead.erl b/lib/compiler/src/beam_dead.erl
index ead88b57e9..0cb5040177 100644
--- a/lib/compiler/src/beam_dead.erl
+++ b/lib/compiler/src/beam_dead.erl
@@ -242,8 +242,15 @@ backward([{select,select_val,Reg,{f,Fail0},List0}|Is], D, Acc) ->
List = shortcut_select_list(List0, Reg, D, []),
Fail1 = shortcut_label(Fail0, D),
Fail = shortcut_bs_test(Fail1, Is, D),
- Sel = {select,select_val,Reg,{f,Fail},List},
- backward(Is, D, [Sel|Acc]);
+ case List of
+ [{atom,B1},F,{atom,B2},F] when B1 =:= not B2 ->
+ Test = {test,is_boolean,{f,Fail},[Reg]},
+ Jump = {jump,F},
+ backward([Jump,Test|Is], D, Acc);
+ [_|_] ->
+ Sel = {select,select_val,Reg,{f,Fail},List},
+ backward(Is, D, [Sel|Acc])
+ end;
backward([{jump,{f,To0}},{move,Src,Reg}=Move|Is], D, Acc) ->
To = shortcut_select_label(To0, Reg, Src, D),
Jump = {jump,{f,To}},
@@ -295,7 +302,18 @@ backward([{test,Op,{f,To0},Ops0}|Is], D, Acc) ->
is_eq_exact -> combine_eqs(To, Ops0, D, Acc);
_ -> {test,Op,{f,To},Ops0}
end,
- backward(Is, D, [I|Acc]);
+ case {I,Acc} of
+ {{test,is_atom,Fail,Ops0},[{test,is_boolean,Fail,Ops0}|_]} ->
+ %% An is_atom test before an is_boolean test (with the
+ %% same failure label) is redundant.
+ backward(Is, D, Acc);
+ {{test,_,_,_},_} ->
+ %% Still a test instruction. Done.
+ backward(Is, D, [I|Acc]);
+ {_,_} ->
+ %% Rewritten to a select_val. Rescan.
+ backward([I|Is], D, Acc)
+ end;
backward([{test,Op,{f,To0},Live,Ops0,Dst}|Is], D, Acc) ->
To1 = shortcut_bs_test(To0, Is, D),
To2 = shortcut_label(To1, D),
diff --git a/lib/compiler/src/beam_peep.erl b/lib/compiler/src/beam_peep.erl
index 17fd2e502a..75be86b83f 100644
--- a/lib/compiler/src/beam_peep.erl
+++ b/lib/compiler/src/beam_peep.erl
@@ -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 +83,6 @@ 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([{test,Op,_,Ops}=I|Is], SeenTests0, Acc) ->
case beam_utils:is_pure_test(I) of
false ->
@@ -121,16 +103,6 @@ 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.