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authorBjörn Gustavsson <[email protected]>2015-09-23 07:23:15 +0200
committerBjörn Gustavsson <[email protected]>2015-09-28 10:26:39 +0200
commitc0c5943c3a2646a3383d974c2a1afcff8c5d16d3 (patch)
treeb0e7ab5d8c7aa77aadc14944703922c9f6a6edba /lib/compiler/src
parentae125a3bc62c2165a9db028e12aa6e9f90c7d9cf (diff)
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beam_type: Improve optimization by keeping track of integers
The ASN.1 compiler often generates code similar to: f(<<0:1,...>>) -> ...; f(<<1:1,...>>) -> .... Internally that will be rewritten to (conceptually): f(<<B:1,Tail/binary>>) -> case B of 0 -> case Tail of ... end; 1 -> case Tail of ... end; _ -> error(case_clause) end. Since B comes from a bit field of one bit, we know that the only possible values are 0 and 1. Therefore the error clause can be eliminated like this: f(<<B:1,Tail/binary>>) -> case B of 0 -> case Tail of ... end; _ -> case Tail of ... end end. Similarly, we can also a deduce the range for an integer from a 'band' operation with a literal integer. While we are at it, also add a test case to improve the coverage.
Diffstat (limited to 'lib/compiler/src')
-rw-r--r--lib/compiler/src/beam_type.erl121
1 files changed, 110 insertions, 11 deletions
diff --git a/lib/compiler/src/beam_type.erl b/lib/compiler/src/beam_type.erl
index bb91bbcc0a..17ce7082f6 100644
--- a/lib/compiler/src/beam_type.erl
+++ b/lib/compiler/src/beam_type.erl
@@ -23,7 +23,8 @@
-export([module/2]).
--import(lists, [foldl/3,reverse/1,filter/2]).
+-import(lists, [filter/2,foldl/3,keyfind/3,member/2,
+ reverse/1,reverse/2,sort/1]).
module({Mod,Exp,Attr,Fs0,Lc}, _Opts) ->
Fs = [function(F) || F <- Fs0],
@@ -94,6 +95,12 @@ simplify_basic_1([{set,[D],[TupleReg],{get_tuple_element,0}}=I|Is0], Ts0, Acc) -
end;
simplify_basic_1([{set,_,_,{try_catch,_,_}}=I|Is], _Ts, Acc) ->
simplify_basic_1(Is, tdb_new(), [I|Acc]);
+simplify_basic_1([{test,is_integer,_,[R]}=I|Is], Ts, Acc) ->
+ case tdb_find(R, Ts) of
+ integer -> simplify_basic_1(Is, Ts, Acc);
+ {integer,_} -> simplify_basic_1(Is, Ts, Acc);
+ _ -> simplify_basic_1(Is, Ts, [I|Acc])
+ end;
simplify_basic_1([{test,is_tuple,_,[R]}=I|Is], Ts, Acc) ->
case tdb_find(R, Ts) of
{tuple,_,_} -> simplify_basic_1(Is, Ts, Acc);
@@ -137,6 +144,14 @@ simplify_basic_1([{test,is_record,_,[R,{atom,_}=Tag,{integer,Arity}]}=I|Is], Ts0
Ts = update(I, Ts0),
simplify_basic_1(Is, Ts, [I|Acc])
end;
+simplify_basic_1([{select,select_val,Reg,_,_}=I0|Is], Ts, Acc) ->
+ I = case tdb_find(Reg, Ts) of
+ {integer,Range} ->
+ simplify_select_val_int(I0, Range);
+ _ ->
+ I0
+ end,
+ simplify_basic_1(Is, tdb_new(), [I|Acc]);
simplify_basic_1([I|Is], Ts0, Acc) ->
Ts = update(I, Ts0),
simplify_basic_1(Is, Ts, [I|Acc]);
@@ -144,6 +159,23 @@ simplify_basic_1([], Ts, Acc) ->
Is = reverse(Acc),
{Is,Ts}.
+simplify_select_val_int({select,select_val,R,_,L0}=I, {Min,Max}) ->
+ Vs = sort([V || {integer,V} <- L0]),
+ case eq_ranges(Vs, Min, Max) of
+ false -> I;
+ true -> simplify_select_val_1(L0, {integer,Max}, R, [])
+ end.
+
+simplify_select_val_1([Val,F|T], Val, R, Acc) ->
+ L = reverse(Acc, T),
+ {select,select_val,R,F,L};
+simplify_select_val_1([V,F|T], Val, R, Acc) ->
+ simplify_select_val_1(T, Val, R, [F,V|Acc]).
+
+eq_ranges([H], H, H) -> true;
+eq_ranges([H|T], H, Max) -> eq_ranges(T, H+1, Max);
+eq_ranges(_, _, _) -> false.
+
%% simplify_float([Instruction], TypeDatabase) ->
%% {[Instruction],TypeDatabase'} | not_possible
%% Simplify floating point operations in blocks.
@@ -390,6 +422,13 @@ update({set,[D],[S],{alloc,_,{gc_bif,float,{f,0}}}}, Ts0) ->
true -> tdb_update([{D,float}], Ts0);
false -> Ts0
end;
+update({set,[D],[S1,S2],{alloc,_,{gc_bif,'band',{f,0}}}}, Ts) ->
+ case keyfind(integer, 1, [S1,S2]) of
+ {integer,N} ->
+ update_band(N, D, Ts);
+ false ->
+ tdb_update([{D,integer}], Ts)
+ end;
update({set,[D],[S1,S2],{alloc,_,{gc_bif,'/',{f,0}}}}, Ts0) ->
%% Make sure we reject non-numeric literals.
case possibly_numeric(S1) andalso possibly_numeric(S2) of
@@ -397,15 +436,17 @@ update({set,[D],[S1,S2],{alloc,_,{gc_bif,'/',{f,0}}}}, Ts0) ->
false -> Ts0
end;
update({set,[D],[S1,S2],{alloc,_,{gc_bif,Op,{f,0}}}}, Ts0) ->
- case arith_op(Op) of
- no ->
- tdb_update([{D,kill}], Ts0);
- {yes,_} ->
+ case op_type(Op) of
+ integer ->
+ tdb_update([{D,integer}], Ts0);
+ {float,_} ->
case {tdb_find(S1, Ts0),tdb_find(S2, Ts0)} of
{float,_} -> tdb_update([{D,float}], Ts0);
{_,float} -> tdb_update([{D,float}], Ts0);
{_,_} -> tdb_update([{D,kill}], Ts0)
- end
+ end;
+ unknown ->
+ tdb_update([{D,kill}], Ts0)
end;
update({set,[],_Src,_Op}, Ts0) -> Ts0;
update({set,[D],_Src,_Op}, Ts0) ->
@@ -437,6 +478,8 @@ update({test,is_record,_Fail,[Src,Tag,{integer,Arity}]}, Ts) ->
tdb_update([{Src,{tuple,Arity,[Tag]}}], Ts);
update({test,_Test,_Fail,_Other}, Ts) ->
Ts;
+update({test,bs_get_integer2,_,_,Args,Dst}, Ts) ->
+ tdb_update([{Dst,get_bs_integer_type(Args)}], Ts);
update({call_ext,Ar,{extfunc,math,Math,Ar}}, Ts) ->
case is_math_bif(Math, Ar) of
true -> tdb_update([{{x,0},float}], Ts);
@@ -453,10 +496,43 @@ update({call,_Arity,_Func}, Ts) -> tdb_kill_xregs(Ts);
update({call_ext,_Arity,_Func}, Ts) -> tdb_kill_xregs(Ts);
update({make_fun2,_,_,_,_}, Ts) -> tdb_kill_xregs(Ts);
update({line,_}, Ts) -> Ts;
+update({bs_save2,_,_}, Ts) -> Ts;
+update({bs_restore2,_,_}, Ts) -> Ts;
%% The instruction is unknown. Kill all information.
update(_I, _Ts) -> tdb_new().
+update_band(N, Reg, Ts) ->
+ Type = update_band_1(N, 0),
+ tdb_update([{Reg,Type}], Ts).
+
+update_band_1(N, Bits) when Bits < 64 ->
+ case 1 bsl Bits of
+ P when P =:= N + 1 ->
+ {integer,{0,N}};
+ P when P > N + 1 ->
+ integer;
+ _ ->
+ update_band_1(N, Bits+1)
+ end;
+update_band_1(_, _) ->
+ %% Negative or large positive number. Give up.
+ integer.
+
+get_bs_integer_type([_,{integer,N},U,{field_flags,Fl}])
+ when N*U < 64 ->
+ NumBits = N*U,
+ case member(unsigned, Fl) of
+ true ->
+ {integer,{0,(1 bsl NumBits)-1}};
+ false ->
+ %% Signed integer. Don't bother.
+ integer
+ end;
+get_bs_integer_type(_) ->
+ %% Avoid creating ranges with a huge upper limit.
+ integer.
+
is_math_bif(cos, 1) -> true;
is_math_bif(cosh, 1) -> true;
is_math_bif(sin, 1) -> true;
@@ -545,11 +621,22 @@ load_reg(V, Ts, Rs0, Is0) ->
{Rs,Is}
end.
-arith_op('+') -> {yes,fadd};
-arith_op('-') -> {yes,fsub};
-arith_op('*') -> {yes,fmul};
-arith_op('/') -> {yes,fdiv};
-arith_op(_) -> no.
+arith_op(Op) ->
+ case op_type(Op) of
+ {float,Instr} -> {yes,Instr};
+ _ -> no
+ end.
+
+op_type('+') -> {float,fadd};
+op_type('-') -> {float,fsub};
+op_type('*') -> {float,fmul};
+%% '/' and 'band' are specially handled.
+op_type('bor') -> integer;
+op_type('bxor') -> integer;
+op_type('bsl') -> integer;
+op_type('bsr') -> integer;
+op_type('div') -> integer;
+op_type(_) -> unknown.
flush(Rs, [{set,[_],[],{put_tuple,_}}|_]=Is0, Acc0) ->
Acc = flush_all(Rs, Is0, Acc0),
@@ -639,6 +726,9 @@ checkerror_2(OrigIs) -> [{set,[],[],fcheckerror}|OrigIs].
%%% of the first element).
%%%
%%% 'float' means that the register contains a float.
+%%%
+%%% 'integer' or {integer,{Min,Max}} that the register contains an
+%%% integer.
%% tdb_new() -> EmptyDataBase
%% Creates a new, empty type database.
@@ -728,10 +818,19 @@ merge_type_info({tuple,Sz1,[]}, {tuple,_Sz2,First}=Tuple2) ->
merge_type_info({tuple,Sz1,First}, Tuple2);
merge_type_info({tuple,_Sz1,First}=Tuple1, {tuple,Sz2,_}) ->
merge_type_info(Tuple1, {tuple,Sz2,First});
+merge_type_info(integer, {integer,_}=Int) ->
+ Int;
+merge_type_info({integer,_}=Int, integer) ->
+ Int;
+merge_type_info({integer,{Min1,Max1}}, {integer,{Min2,Max2}}) ->
+ {integer,{max(Min1, Min2),min(Max1, Max2)}};
merge_type_info(NewType, _) ->
verify_type(NewType),
NewType.
+verify_type(integer) -> ok;
+verify_type({integer,{Min,Max}})
+ when is_integer(Min), is_integer(Max) -> ok;
verify_type(map) -> ok;
verify_type(nonempty_list) -> ok;
verify_type({tuple,Sz,[]}) when is_integer(Sz) -> ok;