Merge branch 'maint'

* maint:
  erts: Fix bad loader optimization of get_tuple_element
  beam_ssa_type: Fix incorrect bitstring unit determination

3 files changed, 37 insertions, 14 deletions

diff --git a/lib/compiler/src/beam_ssa_type.erl b/lib/compiler/src/beam_ssa_type.erl
index f1c0030b3c..612277393e 100644
--- a/lib/compiler/src/beam_ssa_type.erl
+++ b/lib/compiler/src/beam_ssa_type.erl
@@ -927,15 +927,8 @@ type({bif,Bif}, Args, Ts, _Ds) ->
         Type ->
             Type
     end;
-type(bs_init, [#b_literal{val=Type}|Args], _Ts, _Ds) ->
-    case {Type,Args} of
-        {new,[_,#b_literal{val=Unit}]} ->
-            {binary,Unit};
-        {append,[_,_,#b_literal{val=Unit}]} ->
-            {binary,Unit};
-        {private_append,[_,_,#b_literal{val=Unit}]} ->
-            {binary,Unit}
-    end;
+type(bs_init, _Args, _Ts, _Ds) ->
+    {binary, 1};
 type(bs_extract, [Ctx], Ts, _Ds) ->
     #t_bs_match{type=Type} = get_type(Ctx, Ts),
     Type;
diff --git a/lib/compiler/test/beam_type_SUITE.erl b/lib/compiler/test/beam_type_SUITE.erl
index 2297c2e0f5..076a604aa4 100644
--- a/lib/compiler/test/beam_type_SUITE.erl
+++ b/lib/compiler/test/beam_type_SUITE.erl
@@ -24,7 +24,7 @@
 	 integers/1,numbers/1,coverage/1,booleans/1,setelement/1,
 	 cons/1,tuple/1,record_float/1,binary_float/1,float_compare/1,
 	 arity_checks/1,elixir_binaries/1,find_best/1,
-         test_size/1,cover_lists_functions/1,list_append/1]).
+         test_size/1,cover_lists_functions/1,list_append/1,bad_binary_unit/1]).
 
 suite() -> [{ct_hooks,[ts_install_cth]}].
 
@@ -48,7 +48,8 @@ groups() ->
        find_best,
        test_size,
        cover_lists_functions,
-       list_append
+       list_append,
+       bad_binary_unit
       ]}].
 
 init_per_suite(Config) ->
@@ -508,5 +509,14 @@ list_append(_Config) ->
     hello = id([]) ++ id(hello),
     ok.
 
+%% OTP-15872: The compiler would treat the "Unit" of bs_init instructions as
+%% the unit of the result instead of the required unit of the input, causing
+%% is_binary checks to be wrongly optimized away.
+bad_binary_unit(_Config) ->
+    Bin = id(<<1,2,3>>),
+    Bitstring = <<Bin/binary,1:1>>,
+    false = is_binary(Bitstring),
+    ok.
+
 id(I) ->
     I.
diff --git a/lib/compiler/test/match_SUITE.erl b/lib/compiler/test/match_SUITE.erl
index 94bfbb0efe..aac9de278d 100644
--- a/lib/compiler/test/match_SUITE.erl
+++ b/lib/compiler/test/match_SUITE.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 2004-2018. All Rights Reserved.
+%% Copyright Ericsson AB 2004-2019. All Rights Reserved.
 %%
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -25,7 +25,7 @@
 	 match_in_call/1,untuplify/1,shortcut_boolean/1,letify_guard/1,
 	 selectify/1,deselectify/1,underscore/1,match_map/1,map_vars_used/1,
 	 coverage/1,grab_bag/1,literal_binary/1,
-         unary_op/1,eq_types/1,match_after_return/1]).
+         unary_op/1,eq_types/1,match_after_return/1,match_right_tuple/1]).
 	 
 -include_lib("common_test/include/ct.hrl").
 
@@ -41,7 +41,7 @@ groups() ->
        shortcut_boolean,letify_guard,selectify,deselectify,
        underscore,match_map,map_vars_used,coverage,
        grab_bag,literal_binary,unary_op,eq_types,
-       match_after_return]}].
+       match_after_return,match_right_tuple]}].
 
 
 init_per_suite(Config) ->
@@ -902,4 +902,24 @@ match_after_return(Config) when is_list(Config) ->
 
 mar_test_tuple(I) -> {gurka, I}.
 
+match_right_tuple(Config) when is_list(Config) ->
+    %% The loader wrongly coalesced certain get_tuple_element sequences, fusing
+    %% the code below into a single i_get_tuple_element2 operating on {x,0}
+    %% even though the first one overwrites it.
+    %%
+    %%    {get_tuple_element,{x,0},0,{x,0}}.
+    %%    {get_tuple_element,{x,0},1,{x,1}}.
+
+    Inner = {id(wrong_element), id(ok)},
+    Outer = {Inner, id(wrong_tuple)},
+    ok = match_right_tuple_1(Outer).
+
+match_right_tuple_1(T) ->
+    {A, _} = T,
+    {_, B} = A,
+    %% The call ensures that A is in {x,0} and B is in {x,1}
+    id(force_succ_regs(A, B)).
+
+force_succ_regs(_A, B) -> B.
+
 id(I) -> I.