Simplify optimizations by introducing is_nil late

4 files changed, 4 insertions, 17 deletions

diff --git a/lib/compiler/src/beam_a.erl b/lib/compiler/src/beam_a.erl
index 6fd4ace540..a26f245446 100644
--- a/lib/compiler/src/beam_a.erl
+++ b/lib/compiler/src/beam_a.erl
@@ -113,6 +113,8 @@ rename_instr({put_map_exact,Fail,S,D,R,L}) ->
     {put_map,Fail,exact,S,D,R,L};
 rename_instr({test,has_map_fields,Fail,Src,{list,List}}) ->
     {test,has_map_fields,Fail,[Src|List]};
+rename_instr({test,is_nil,Fail,[Src]}) ->
+    {test,is_eq_exact,Fail,[Src,nil]};
 rename_instr({select_val=I,Reg,Fail,{list,List}}) ->
     {select,I,Reg,Fail,List};
 rename_instr({select_tuple_arity=I,Reg,Fail,{list,List}}) ->
diff --git a/lib/compiler/src/beam_dead.erl b/lib/compiler/src/beam_dead.erl
index efad082152..eb5652b69a 100644
--- a/lib/compiler/src/beam_dead.erl
+++ b/lib/compiler/src/beam_dead.erl
@@ -85,11 +85,6 @@ move_move_into_block([], Acc) -> reverse(Acc).
 %%%
 %%% or in:
 %%%
-%%%           test is_nil SomeLabel Dst
-%%%           move nil Dst
-%%%
-%%% or in:
-%%%
 %%%           select_val Register FailLabel [... Literal => L1...]
 %%%                      .
 %%%                      .
@@ -140,13 +135,8 @@ forward([{test,is_eq_exact,_,[Same,Same]}|Is], D, Lc, Acc) ->
 forward([{test,is_eq_exact,_,[Dst,Src]}=I,
 	 {block,[{set,[Dst],[Src],move}|Bl]}|Is], D, Lc, Acc) ->
     forward([I,{block,Bl}|Is], D, Lc, Acc);
-forward([{test,is_nil,_,[Dst]}=I,
-	 {block,[{set,[Dst],[nil],move}|Bl]}|Is], D, Lc, Acc) ->
-    forward([I,{block,Bl}|Is], D, Lc, Acc);
 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,_,_,_}=I|Is]=Is0, D, Lc, Acc) ->
     %% Help the second, backward pass to by inserting labels after
     %% relational operators so that they can be skipped if they are
@@ -900,8 +890,6 @@ normalize_op({test,is_eq_exact,{f,Fail},Ops}) ->
     normalize_op_1('=:=', Ops, Fail);
 normalize_op({test,is_ne_exact,{f,Fail},Ops}) ->
     normalize_op_1('=/=', Ops, Fail);
-normalize_op({test,is_nil,{f,Fail},[R]}) ->
-    normalize_op_1('=:=', [R,nil], Fail);
 normalize_op({test,Op,{f,Fail},[R]}) ->
     case erl_internal:new_type_test(Op, 1) of
 	true -> {{Op,R},Fail};
diff --git a/lib/compiler/src/beam_utils.erl b/lib/compiler/src/beam_utils.erl
index 989294cf0a..317252e87a 100644
--- a/lib/compiler/src/beam_utils.erl
+++ b/lib/compiler/src/beam_utils.erl
@@ -224,16 +224,12 @@ bif_to_test('=<', [A,B], Fail) -> {test,is_ge,Fail,[B,A]};
 bif_to_test('>', [A,B], Fail) -> {test,is_lt,Fail,[B,A]};
 bif_to_test('<', [_,_]=Ops, Fail) -> {test,is_lt,Fail,Ops};
 bif_to_test('>=', [_,_]=Ops, Fail) -> {test,is_ge,Fail,Ops};
-bif_to_test('==', [A,nil], Fail) -> {test,is_nil,Fail,[A]};
-bif_to_test('==', [nil,A], Fail) -> {test,is_nil,Fail,[A]};
 bif_to_test('==', [C,A], Fail) when ?is_const(C) ->
     {test,is_eq,Fail,[A,C]};
 bif_to_test('==', [_,_]=Ops, Fail) -> {test,is_eq,Fail,Ops};
 bif_to_test('/=', [C,A], Fail) when ?is_const(C) ->
     {test,is_ne,Fail,[A,C]};
 bif_to_test('/=', [_,_]=Ops, Fail) -> {test,is_ne,Fail,Ops};
-bif_to_test('=:=', [A,nil], Fail) -> {test,is_nil,Fail,[A]};
-bif_to_test('=:=', [nil,A], Fail) -> {test,is_nil,Fail,[A]};
 bif_to_test('=:=', [C,A], Fail) when ?is_const(C) ->
     {test,is_eq_exact,Fail,[A,C]};
 bif_to_test('=:=', [_,_]=Ops, Fail) -> {test,is_eq_exact,Fail,Ops};
@@ -256,7 +252,6 @@ is_pure_test({test,is_eq_exact,_,[_,_]}) -> true;
 is_pure_test({test,is_ne_exact,_,[_,_]}) -> true;
 is_pure_test({test,is_ge,_,[_,_]}) -> true;
 is_pure_test({test,is_lt,_,[_,_]}) -> true;
-is_pure_test({test,is_nil,_,[_]}) -> true;
 is_pure_test({test,is_nonempty_list,_,[_]}) -> true;
 is_pure_test({test,is_tagged_tuple,_,[_,_,_]}) -> true;
 is_pure_test({test,test_arity,_,[_,_]}) -> true;
diff --git a/lib/compiler/src/beam_z.erl b/lib/compiler/src/beam_z.erl
index 1c9d762eb1..677094b3cd 100644
--- a/lib/compiler/src/beam_z.erl
+++ b/lib/compiler/src/beam_z.erl
@@ -110,6 +110,8 @@ undo_rename({test,has_map_fields,Fail,[Src|List]}) ->
     {test,has_map_fields,Fail,Src,{list,List}};
 undo_rename({get_map_elements,Fail,Src,{list,List}}) ->
     {get_map_elements,Fail,Src,{list,List}};
+undo_rename({test,is_eq_exact,Fail,[Src,nil]}) ->
+    {test,is_nil,Fail,[Src]};
 undo_rename({select,I,Reg,Fail,List}) ->
     {I,Reg,Fail,{list,List}};
 undo_rename(I) -> I.