beam_type: Improve optimizations by keeping track of booleans

There is an optimization in beam_block to simplify a select_val
on a known boolean value. We can implement this optimization
in a cleaner way in beam_type and it will also be applicable
in more situations. (When I added the optimization to beam_type
without removing the optimization from beam_block, the optimization
was applied 66 times.)

3 files changed, 41 insertions, 36 deletions

diff --git a/lib/compiler/src/beam_block.erl b/lib/compiler/src/beam_block.erl
index 741fdbb973..10dbaf462c 100644
--- a/lib/compiler/src/beam_block.erl
+++ b/lib/compiler/src/beam_block.erl
@@ -58,33 +58,6 @@ blockify(Is) ->
 blockify([{loop_rec,{f,Fail},{x,0}},{loop_rec_end,_Lbl},{label,Fail}|Is], Acc) ->
     %% Useless instruction sequence.
     blockify(Is, Acc);
-blockify([{test,is_atom,{f,Fail},[Reg]}=I|
-	  [{select,select_val,Reg,{f,Fail},
-	    [{atom,false},{f,_}=BrFalse,
-	     {atom,true}=AtomTrue,{f,_}=BrTrue]}|Is]=Is0],
-	 [{block,Bl}|_]=Acc) ->
-    case is_last_bool(Bl, Reg) of
-	false ->
-	    blockify(Is0, [I|Acc]);
-	true ->
-	    %% The last instruction is a boolean operator/guard BIF that can't fail.
-	    %% We can convert the three-way branch to a two-way branch (eliminating
-	    %% the reference to the failure label).
-	    blockify(Is, [{jump,BrTrue},
-			  {test,is_eq_exact,BrFalse,[Reg,AtomTrue]}|Acc])
-    end;
-blockify([{test,is_atom,{f,Fail},[Reg]}=I|
-	  [{select,select_val,Reg,{f,Fail},
-	    [{atom,true}=AtomTrue,{f,_}=BrTrue,
-	     {atom,false},{f,_}=BrFalse]}|Is]=Is0],
-	 [{block,Bl}|_]=Acc) ->
-    case is_last_bool(Bl, Reg) of
-	false ->
-	    blockify(Is0, [I|Acc]);
-	true ->
-	    blockify(Is, [{jump,BrTrue},
-			  {test,is_eq_exact,BrFalse,[Reg,AtomTrue]}|Acc])
-    end;
 blockify([I|Is0]=IsAll, Acc) ->
     case collect(I) of
 	error -> blockify(Is0, [I|Acc]);
@@ -94,13 +67,6 @@ blockify([I|Is0]=IsAll, Acc) ->
     end;
 blockify([], Acc) -> reverse(Acc).
 
-is_last_bool([{set,[Reg],As,{bif,N,_}}], Reg) ->
-    Ar = length(As),
-    erl_internal:new_type_test(N, Ar) orelse erl_internal:comp_op(N, Ar)
-	orelse erl_internal:bool_op(N, Ar);
-is_last_bool([_|Is], Reg) -> is_last_bool(Is, Reg);
-is_last_bool([], _) -> false.
-
 collect_block(Is) ->
     collect_block(Is, []).
 
diff --git a/lib/compiler/src/beam_type.erl b/lib/compiler/src/beam_type.erl
index 17ce7082f6..4b45c28623 100644
--- a/lib/compiler/src/beam_type.erl
+++ b/lib/compiler/src/beam_type.erl
@@ -95,6 +95,11 @@ 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_atom,_,[R]}=I|Is], Ts, Acc) ->
+    case tdb_find(R, Ts) of
+	boolean -> simplify_basic_1(Is, Ts, Acc);
+	_ -> simplify_basic_1(Is, Ts, [I|Acc])
+    end;
 simplify_basic_1([{test,is_integer,_,[R]}=I|Is], Ts, Acc) ->
     case tdb_find(R, Ts) of
 	integer -> simplify_basic_1(Is, Ts, Acc);
@@ -148,6 +153,8 @@ 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);
+	    boolean ->
+		simplify_select_val_bool(I0);
 	    _ ->
 		I0
 	end,
@@ -166,6 +173,15 @@ simplify_select_val_int({select,select_val,R,_,L0}=I, {Min,Max}) ->
 	true -> simplify_select_val_1(L0, {integer,Max}, R, [])
     end.
 
+simplify_select_val_bool({select,select_val,R,_,L}=I) ->
+    Vs = sort([V || {atom,V} <- L]),
+    case Vs of
+	[false,true] ->
+	    simplify_select_val_1(L, {atom,false}, R, []);
+	_ ->
+	    I
+    end.
+
 simplify_select_val_1([Val,F|T], Val, R, Acc) ->
     L = reverse(Acc, T),
     {select,select_val,R,F,L};
@@ -414,6 +430,17 @@ update({set,[D],[{integer,I},Reg],{bif,element,_}}, Ts0) ->
     tdb_update([{Reg,{tuple,I,[]}},{D,kill}], Ts0);
 update({set,[D],[_Index,Reg],{bif,element,_}}, Ts0) ->
     tdb_update([{Reg,{tuple,0,[]}},{D,kill}], Ts0);
+update({set,[D],Args,{bif,N,_}}, Ts0) ->
+    Ar = length(Args),
+    BoolOp = erl_internal:new_type_test(N, Ar) orelse
+	erl_internal:comp_op(N, Ar) orelse
+	erl_internal:bool_op(N, Ar),
+    case BoolOp of
+	true ->
+	    tdb_update([{D,boolean}], Ts0);
+	false ->
+	    tdb_update([{D,kill}], Ts0)
+    end;
 update({set,[D],[S],{get_tuple_element,0}}, Ts) ->
     tdb_update([{D,{tuple_element,S,0}}], Ts);
 update({set,[D],[S],{alloc,_,{gc_bif,float,{f,0}}}}, Ts0) ->
@@ -828,6 +855,7 @@ merge_type_info(NewType, _) ->
     verify_type(NewType),
     NewType.
 
+verify_type(boolean) -> ok;
 verify_type(integer) -> ok;
 verify_type({integer,{Min,Max}})
   when is_integer(Min), is_integer(Max) -> ok;
diff --git a/lib/compiler/test/beam_type_SUITE.erl b/lib/compiler/test/beam_type_SUITE.erl
index 8d99d76180..8d5c0190ed 100644
--- a/lib/compiler/test/beam_type_SUITE.erl
+++ b/lib/compiler/test/beam_type_SUITE.erl
@@ -21,7 +21,7 @@
 
 -export([all/0,suite/0,groups/0,init_per_suite/1,end_per_suite/1,
 	 init_per_group/2,end_per_group/2,
-	 integers/1,coverage/1]).
+	 integers/1,coverage/1,booleans/1]).
 
 suite() -> [{ct_hooks,[ts_install_cth]}].
 
@@ -32,7 +32,8 @@ all() ->
 groups() ->
     [{p,[parallel],
       [integers,
-       coverage
+       coverage,
+       booleans
       ]}].
 
 init_per_suite(Config) ->
@@ -83,5 +84,15 @@ coverage(_Config) ->
 
     ok.
 
+booleans(_Config) ->
+    {'EXIT',{{case_clause,_},_}} = (catch do_booleans(42)),
+    ok.
+
+do_booleans(B) ->
+    case is_integer(B) of
+	yes -> yes;
+	no -> no
+    end.
+
 id(I) ->
     I.