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authorBjörn Gustavsson <[email protected]>2010-03-12 10:42:45 +0100
committerBjörn Gustavsson <[email protected]>2010-06-02 11:51:25 +0200
commite96f49fbba499b56026735a302fbfbdf7524db66 (patch)
tree4f09c0cbea552c3c28040c86b8bd631e3ba6c144 /lib/compiler/src
parent470c91d43eae54f63661645acbce4b92d73287cc (diff)
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beam_dead: Combine is_eq_exact instructions into select_val instructions
Combine a sequence of chained is_eq_exact instructions into a select_val instruction.
Diffstat (limited to 'lib/compiler/src')
-rw-r--r--lib/compiler/src/beam_dead.erl48
1 files changed, 43 insertions, 5 deletions
diff --git a/lib/compiler/src/beam_dead.erl b/lib/compiler/src/beam_dead.erl
index 7b4cd814a2..e690d1b96b 100644
--- a/lib/compiler/src/beam_dead.erl
+++ b/lib/compiler/src/beam_dead.erl
@@ -281,12 +281,12 @@ forward([{test,is_eq_exact,_,[Dst,Src]}=I,{move,Src,Dst}|Is], D, Lc, Acc) ->
forward([I|Is], D, Lc, Acc);
forward([{test,is_nil,_,[Dst]}=I,{move,nil,Dst}|Is], D, Lc, Acc) ->
forward([I|Is], D, Lc, Acc);
-forward([{test,is_eq_exact,_,[_,{atom,_}]}=I|Is], D, Lc, [{label,_}|_]=Acc) ->
+forward([{test,is_eq_exact,_,_}=I|Is], D, Lc, Acc) ->
case Is of
[{label,_}|_] -> forward(Is, D, Lc, [I|Acc]);
_ -> forward(Is, D, Lc+1, [{label,Lc},I|Acc])
end;
-forward([{test,is_ne_exact,_,[_,{atom,_}]}=I|Is], D, Lc, [{label,_}|_]=Acc) ->
+forward([{test,is_ne_exact,_,_}=I|Is], D, Lc, Acc) ->
case Is of
[{label,_}|_] -> forward(Is, D, Lc, [I|Acc]);
_ -> forward(Is, D, Lc+1, [{label,Lc},I|Acc])
@@ -371,10 +371,10 @@ backward([{test,bs_start_match2,{f,To0},Live,[Src|_]=Info,Dst}|Is], D, Acc) ->
To = shortcut_bs_start_match(To0, Src, D),
I = {test,bs_start_match2,{f,To},Live,Info,Dst},
backward(Is, D, [I|Acc]);
-backward([{test,is_eq_exact=Op,{f,To0},[Reg,{atom,Val}]=Ops}|Is], D, Acc) ->
+backward([{test,is_eq_exact,{f,To0},[Reg,{atom,Val}]=Ops}|Is], D, Acc) ->
To1 = shortcut_bs_test(To0, Is, D),
To = shortcut_fail_label(To1, Reg, Val, D),
- I = {test,Op,{f,To},Ops},
+ I = combine_eqs(To, Ops, D, Acc),
backward(Is, D, [I|Acc]);
backward([{test,Op,{f,To0},Ops0}|Is], D, Acc) ->
To1 = shortcut_bs_test(To0, Is, D),
@@ -394,7 +394,10 @@ backward([{test,Op,{f,To0},Ops0}|Is], D, Acc) ->
_Code ->
To2
end,
- I = {test,Op,{f,To},Ops0},
+ I = case Op of
+ is_eq_exact -> combine_eqs(To, Ops0, D, Acc);
+ _ -> {test,Op,{f,To},Ops0}
+ end,
backward(Is, D, [I|Acc]);
backward([{test,Op,{f,To0},Live,Ops0,Dst}|Is], D, Acc) ->
To1 = shortcut_bs_test(To0, Is, D),
@@ -519,6 +522,41 @@ bif_to_test(Name, Args, Fail) ->
not_possible() -> throw(not_possible).
+%% combine_eqs(To, Operands, Acc) -> Instruction.
+%% Combine two is_eq_exact instructions or (an is_eq_exact
+%% instruction and a select_val instruction) to a select_val
+%% instruction if possible.
+%%
+%% Example:
+%%
+%% is_eq_exact F1 Reg Lit1 select_val Reg F2 [ Lit1 L1
+%% L1: . Lit2 L2 ]
+%% .
+%% . ==>
+%% .
+%% F1: is_eq_exact F2 Reg Lit2 F1: is_eq_exact F2 Reg Lit2
+%% L2: .... L2:
+%%
+combine_eqs(To, [Reg,{Type,_}=Lit1]=Ops, D, [{label,L1}|_])
+ when Type =:= atom; Type =:= integer ->
+ case beam_utils:code_at(To, D) of
+ [{test,is_eq_exact,{f,F2},[Reg,{Type,_}=Lit2]},
+ {label,L2}|_] when Lit1 =/= Lit2 ->
+ {select_val,Reg,{f,F2},{list,[Lit1,{f,L1},Lit2,{f,L2}]}};
+ [{select_val,Reg,{f,F2},{list,[{Type,_}|_]=List0}}|_] ->
+ List = remove_from_list(Lit1, List0),
+ {select_val,Reg,{f,F2},{list,[Lit1,{f,L1}|List]}};
+ _Is ->
+ {test,is_eq_exact,{f,To},Ops}
+ end;
+combine_eqs(To, Ops, _D, _Acc) ->
+ {test,is_eq_exact,{f,To},Ops}.
+
+remove_from_list(Lit, [Lit,{f,_}|T]) ->
+ T;
+remove_from_list(Lit, [Val,{f,_}=Fail|T]) ->
+ [Val,Fail|remove_from_list(Lit, T)];
+remove_from_list(_, []) -> [].
%% shortcut_bs_test(TargetLabel, [Instruction], D) -> TargetLabel'
%% Try to shortcut the failure label for a bit syntax matching.