Merge pull request #1965 from bjorng/bjorn/compiler/misc-cleanups

Minor cleanups and bug fixes of the compiler

8 files changed, 220 insertions, 177 deletions

diff --git a/lib/compiler/src/beam_a.erl b/lib/compiler/src/beam_a.erl
index 0abc845310..dd2537a699 100644
--- a/lib/compiler/src/beam_a.erl
+++ b/lib/compiler/src/beam_a.erl
@@ -59,6 +59,9 @@ rename_instrs([{test,is_eq_exact,_,[Dst,Src]}=Test,
 rename_instrs([{test,is_eq_exact,_,[Same,Same]}|Is]) ->
     %% Same literal or same register. Will always succeed.
     rename_instrs(Is);
+rename_instrs([{loop_rec,{f,Fail},{x,0}},{loop_rec_end,_},{label,Fail}|Is]) ->
+    %% This instruction sequence does nothing.
+    rename_instrs(Is);
 rename_instrs([{apply_last,A,N}|Is]) ->
     [{apply,A},{deallocate,N},return|rename_instrs(Is)];
 rename_instrs([{call_last,A,F,N}|Is]) ->
diff --git a/lib/compiler/src/beam_block.erl b/lib/compiler/src/beam_block.erl
index d28c0fd9e4..9d8d5b2b0c 100644
--- a/lib/compiler/src/beam_block.erl
+++ b/lib/compiler/src/beam_block.erl
@@ -49,9 +49,6 @@ function({function,Name,Arity,CLabel,Is0}) ->
 blockify(Is) ->
     blockify(Is, []).
 
-blockify([{loop_rec,{f,Fail},{x,0}},{loop_rec_end,_Lbl},{label,Fail}|Is], Acc) ->
-    %% Useless instruction sequence.
-    blockify(Is, Acc);
 blockify([I|Is0]=IsAll, Acc) ->
     case collect(I) of
 	error -> blockify(Is0, [I|Acc]);
diff --git a/lib/compiler/src/beam_clean.erl b/lib/compiler/src/beam_clean.erl
index f5f0ac2218..7299654476 100644
--- a/lib/compiler/src/beam_clean.erl
+++ b/lib/compiler/src/beam_clean.erl
@@ -23,17 +23,15 @@
 
 -export([module/2]).
 -export([clean_labels/1]).
--import(lists, [foldl/3]).
 
 -spec module(beam_utils:module_code(), [compile:option()]) ->
                     {'ok',beam_utils:module_code()}.
 
 module({Mod,Exp,Attr,Fs0,_}, Opts) ->
     Order = [Lbl || {function,_,_,Lbl,_} <- Fs0],
-    All = foldl(fun({function,_,_,Lbl,_}=Func,D) -> dict:store(Lbl, Func, D) end,
-		dict:new(), Fs0),
+    All = maps:from_list([{Lbl,Func} || {function,_,_,Lbl,_}=Func <- Fs0]),
     WorkList = rootset(Fs0, Exp, Attr),
-    Used = find_all_used(WorkList, All, sets:from_list(WorkList)),
+    Used = find_all_used(WorkList, All, cerl_sets:from_list(WorkList)),
     Fs1 = remove_unused(Order, Used, All),
     {Fs2,Lc} = clean_labels(Fs1),
     Fs = maybe_remove_lines(Fs2, Opts),
@@ -55,16 +53,16 @@ rootset(Fs, Root0, Attr) ->
 %% Remove the unused functions.
 
 remove_unused([F|Fs], Used, All) ->
-    case sets:is_element(F, Used) of
+    case cerl_sets:is_element(F, Used) of
 	false -> remove_unused(Fs, Used, All);
-	true -> [dict:fetch(F, All)|remove_unused(Fs, Used, All)]
+	true -> [map_get(F, All)|remove_unused(Fs, Used, All)]
     end;
 remove_unused([], _, _) -> [].
-	    
+
 %% Find all used functions.
 
 find_all_used([F|Fs0], All, Used0) ->
-    {function,_,_,_,Code} = dict:fetch(F, All),
+    {function,_,_,_,Code} = map_get(F, All),
     {Fs,Used} = update_work_list(Code, {Fs0,Used0}),
     find_all_used(Fs, All, Used);
 find_all_used([], _All, Used) -> Used.
@@ -78,9 +76,9 @@ update_work_list([_|Is], Sets) ->
 update_work_list([], Sets) -> Sets.
 
 add_to_work_list(F, {Fs,Used}=Sets) ->
-    case sets:is_element(F, Used) of
+    case cerl_sets:is_element(F, Used) of
 	true -> Sets;
-	false -> {[F|Fs],sets:add_element(F, Used)}
+	false -> {[F|Fs],cerl_sets:add_element(F, Used)}
     end.
 
 
diff --git a/lib/compiler/src/beam_flatten.erl b/lib/compiler/src/beam_flatten.erl
index 973d16a1bc..3e6bc1b1ed 100644
--- a/lib/compiler/src/beam_flatten.erl
+++ b/lib/compiler/src/beam_flatten.erl
@@ -32,8 +32,7 @@ module({Mod,Exp,Attr,Fs,Lc}, _Opt) ->
     {ok,{Mod,Exp,Attr,[function(F) || F <- Fs],Lc}}.
 
 function({function,Name,Arity,CLabel,Is0}) ->
-    Is1 = block(Is0),
-    Is = opt(Is1),
+    Is = block(Is0),
     {function,Name,Arity,CLabel,Is}.
 
 block(Is) ->
@@ -43,21 +42,12 @@ block([{block,Is0}|Is1], Acc) -> block(Is1, norm_block(Is0, Acc));
 block([I|Is], Acc) -> block(Is, [I|Acc]);
 block([], Acc) -> reverse(Acc).
 
-norm_block([{set,[],[],{alloc,R,{_,nostack,_,_}=Alloc}}|Is], Acc0) ->
-    case insert_alloc_in_bs_init(Acc0, Alloc) of
-	impossible ->
-	    norm_block(Is, reverse(norm_allocate(Alloc, R), Acc0));
-	Acc ->
-	    norm_block(Is, Acc)
-    end;
 norm_block([{set,[],[],{alloc,R,Alloc}}|Is], Acc0) ->
     norm_block(Is, reverse(norm_allocate(Alloc, R), Acc0));
-norm_block([{set,[D1],[S],get_hd},{set,[D2],[S],get_tl}|Is], Acc) ->
-    I = {get_list,S,D1,D2},
-    norm_block(Is, [I|Acc]);
-norm_block([I|Is], Acc) -> norm_block(Is, [norm(I)|Acc]);
+norm_block([I|Is], Acc) ->
+    norm_block(Is, [norm(I)|Acc]);
 norm_block([], Acc) -> Acc.
-    
+
 norm({set,[D],As,{bif,N,F}})      -> {bif,N,F,As,D};
 norm({set,[D],As,{alloc,R,{gc_bif,N,F}}}) -> {gc_bif,N,F,R,As,D};
 norm({set,[D],[],init})           -> {init,D};
@@ -91,57 +81,3 @@ norm_allocate({nozero,Ns,0,Inits}, Regs) ->
     [{allocate,Ns,Regs}|Inits];
 norm_allocate({nozero,Ns,Nh,Inits}, Regs) ->
     [{allocate_heap,Ns,Nh,Regs}|Inits].
-
-%% insert_alloc_in_bs_init(ReverseInstructionStream, AllocationInfo) ->
-%%                                  impossible | ReverseInstructionStream'
-%%   A bs_init/6 instruction should not be followed by a test heap instruction.
-%%   Given the AllocationInfo from a test heap instruction, merge the
-%%   allocation amounts into the previous bs_init/6 instruction (if any).
-%%
-insert_alloc_in_bs_init([{bs_put,_,_,_}=I|Is], Alloc) ->
-    %% The instruction sequence ends with an bs_put/4 instruction.
-    %% We'll need to search backwards for the bs_init/6 instruction.
-    insert_alloc_1(Is, Alloc, [I]);
-insert_alloc_in_bs_init(_, _) -> impossible.
-
-insert_alloc_1([{bs_init=Op,Fail,Info0,Live,Ss,Dst}|Is],
-	       {_,nostack,Ws2,[]}, Acc) when is_integer(Live) ->
-    %% The number of extra heap words is always in the second position
-    %% in the Info tuple.
-    Ws1 = element(2, Info0),
-    Al = beam_utils:combine_heap_needs(Ws1, Ws2),
-    Info = setelement(2, Info0, Al),
-    I = {Op,Fail,Info,Live,Ss,Dst},
-    reverse(Acc, [I|Is]);
-insert_alloc_1([{bs_put,_,_,_}=I|Is], Alloc, Acc) ->
-    insert_alloc_1(Is, Alloc, [I|Acc]).
-
-%% opt(Is0) -> Is
-%%  Simple peep-hole optimization to move a {move,Any,{x,0}} past
-%%  any kill up to the next call instruction. (To give the loader
-%%  an opportunity to combine the 'move' and the 'call' instructions.)
-%%
-opt(Is) ->
-    opt_1(Is, []).
-
-opt_1([{move,_,{x,0}}=I|Is0], Acc0) ->
-    case move_past_kill(Is0, I, Acc0) of
-	impossible -> opt_1(Is0, [I|Acc0]);
-	{Is,Acc} -> opt_1(Is, Acc)
-    end;
-opt_1([I|Is], Acc) ->
-    opt_1(Is, [I|Acc]);
-opt_1([], Acc) -> reverse(Acc).
-
-move_past_kill([{kill,Src}|_], {move,Src,_}, _) ->
-    impossible;
-move_past_kill([{kill,_}=I|Is], Move, Acc) ->
-    move_past_kill(Is, Move, [I|Acc]);
-move_past_kill([{trim,N,_}=I|Is], {move,Src,Dst}=Move, Acc) ->
-    case Src of
-	{y,Y} when Y < N-> impossible;
-	{y,Y} -> {Is,[{move,{y,Y-N},Dst},I|Acc]};
-	_ -> {Is,[Move,I|Acc]}
-    end;
-move_past_kill(Is, Move, Acc) ->
-    {Is,[Move|Acc]}.
diff --git a/lib/compiler/src/beam_ssa_codegen.erl b/lib/compiler/src/beam_ssa_codegen.erl
index 1c7563faa0..3c14062d0b 100644
--- a/lib/compiler/src/beam_ssa_codegen.erl
+++ b/lib/compiler/src/beam_ssa_codegen.erl
@@ -231,7 +231,7 @@ need_heap_never(_) -> false.
 
 need_heap_blks([{L,#cg_blk{is=Is0}=Blk0}|Bs], H0, Acc) ->
     {Is1,H1} = need_heap_is(reverse(Is0), H0, []),
-    {Ns,H} = need_heap_terminator(Bs, H1),
+    {Ns,H} = need_heap_terminator(Bs, L, H1),
     Is = Ns ++ Is1,
     Blk = Blk0#cg_blk{is=Is},
     need_heap_blks(Bs, H, [{L,Blk}|Acc]);
@@ -241,6 +241,13 @@ need_heap_blks([], H, Acc) ->
 need_heap_is([#cg_alloc{words=Words}=Alloc0|Is], N, Acc) ->
     Alloc = Alloc0#cg_alloc{words=add_heap_words(N, Words)},
     need_heap_is(Is, #need{}, [Alloc|Acc]);
+need_heap_is([#cg_set{anno=Anno,op=bs_init}=I0|Is], N, Acc) ->
+    Alloc = case need_heap_need(N) of
+                [#cg_alloc{words=Need}] -> alloc(Need);
+                [] -> 0
+            end,
+    I = I0#cg_set{anno=Anno#{alloc=>Alloc}},
+    need_heap_is(Is, #need{}, [I|Acc]);
 need_heap_is([#cg_set{op=Op,args=Args}=I|Is], N, Acc) ->
     case classify_heap_need(Op, Args) of
         {put,Words} ->
@@ -256,11 +263,31 @@ need_heap_is([#cg_set{op=Op,args=Args}=I|Is], N, Acc) ->
 need_heap_is([], N, Acc) ->
     {Acc,N}.
 
-need_heap_terminator([{_,#cg_blk{last=#cg_br{succ=Same,fail=Same}}}|_], N) ->
+need_heap_terminator([{_,#cg_blk{last=#cg_br{succ=L,fail=L}}}|_], L, N) ->
+    %% Fallthrough.
     {[],N};
-need_heap_terminator([{_,#cg_blk{}}|_], N) ->
+need_heap_terminator([{_,#cg_blk{is=Is,last=#cg_br{succ=L}}}|_], L, N) ->
+    case need_heap_need(N) of
+        [] ->
+            {[],#need{}};
+        [_|_]=Alloc ->
+            %% If the preceding instructions are a binary construction,
+            %% hoist the allocation and incorporate into the bs_init
+            %% instruction.
+            case reverse(Is) of
+                [#cg_set{op=succeeded},#cg_set{op=bs_init}|_] ->
+                    {[],N};
+                [#cg_set{op=bs_put}|_] ->
+                    {[],N};
+                _ ->
+                    %% Not binary construction. Must emit an allocation
+                    %% instruction in this block.
+                    {Alloc,#need{}}
+            end
+    end;
+need_heap_terminator([{_,#cg_blk{}}|_], _, N) ->
     {need_heap_need(N),#need{}};
-need_heap_terminator([], H) ->
+need_heap_terminator([], _, H) ->
     {need_heap_need(H),#need{}}.
 
 need_heap_need(#need{h=0,f=0}) -> [];
@@ -1041,12 +1068,13 @@ cg_block([#cg_set{op=bs_init,dst=Dst0,args=Args0,anno=Anno}=I,
           #cg_set{op=succeeded,dst=Bool}], {Bool,Fail0}, St) ->
     Fail = bif_fail(Fail0),
     Line = line(Anno),
+    Alloc = map_get(alloc, Anno),
     [#b_literal{val=Kind}|Args1] = Args0,
     case Kind of
         new ->
             [Dst,Size,{integer,Unit}] = beam_args([Dst0|Args1], St),
             Live = get_live(I),
-            {[Line|cg_bs_init(Dst, Size, Unit, Live, Fail)],St};
+            {[Line|cg_bs_init(Dst, Size, Alloc, Unit, Live, Fail)],St};
         private_append ->
             [Dst,Src,Bits,{integer,Unit}] = beam_args([Dst0|Args1], St),
             Flags = {field_flags,[]},
@@ -1056,7 +1084,7 @@ cg_block([#cg_set{op=bs_init,dst=Dst0,args=Args0,anno=Anno}=I,
             [Dst,Src,Bits,{integer,Unit}] = beam_args([Dst0|Args1], St),
             Flags = {field_flags,[]},
             Live = get_live(I),
-            Is = [Line,{bs_append,Fail,Bits,0,Live,Unit,Src,Flags,Dst}],
+            Is = [Line,{bs_append,Fail,Bits,Alloc,Live,Unit,Src,Flags,Dst}],
             {Is,St}
     end;
 cg_block([#cg_set{anno=Anno,op=bs_start_match,dst=Ctx0,args=[Bin0]}=I,
@@ -1204,6 +1232,12 @@ cg_copy_1([#cg_set{dst=Dst0,args=Args}|T], St) ->
     end;
 cg_copy_1([], _St) -> [].
 
+-define(IS_LITERAL(Val), (Val =:= nil orelse
+                          element(1, Val) =:= integer orelse
+                          element(1, Val) =:= float orelse
+                          element(1, Val) =:= atom orelse
+                          element(1, Val) =:= literal)).
+
 bif_to_test('and', [V1,V2], Fail) ->
     [{test,is_eq_exact,Fail,[V1,{atom,true}]},
      {test,is_eq_exact,Fail,[V2,{atom,true}]}];
@@ -1217,15 +1251,99 @@ bif_to_test('or', [V1,V2], {f,Lbl}=Fail) when Lbl =/= 0 ->
 bif_to_test('not', [Var], Fail) ->
     [{test,is_eq_exact,Fail,[Var,{atom,false}]}];
 bif_to_test(Name, Args, Fail) ->
-    [beam_utils:bif_to_test(Name, Args, Fail)].
+    [bif_to_test_1(Name, Args, Fail)].
+
+bif_to_test_1(is_atom,     [_]=Ops, Fail) ->
+    {test,is_atom,Fail,Ops};
+bif_to_test_1(is_boolean,  [_]=Ops, Fail) ->
+    {test,is_boolean,Fail,Ops};
+bif_to_test_1(is_binary,   [_]=Ops, Fail) ->
+    {test,is_binary,Fail,Ops};
+bif_to_test_1(is_bitstring,[_]=Ops, Fail) ->
+    {test,is_bitstr,Fail,Ops};
+bif_to_test_1(is_float,    [_]=Ops, Fail) ->
+    {test,is_float,Fail,Ops};
+bif_to_test_1(is_function, [_]=Ops, Fail) ->
+    {test,is_function,Fail,Ops};
+bif_to_test_1(is_function, [_,_]=Ops, Fail) ->
+    {test,is_function2,Fail,Ops};
+bif_to_test_1(is_integer,  [_]=Ops, Fail) ->
+    {test,is_integer,Fail,Ops};
+bif_to_test_1(is_list,     [_]=Ops, Fail) ->
+    {test,is_list,Fail,Ops};
+bif_to_test_1(is_map,      [_]=Ops, Fail) ->
+    {test,is_map,Fail,Ops};
+bif_to_test_1(is_number,   [_]=Ops, Fail) ->
+    {test,is_number,Fail,Ops};
+bif_to_test_1(is_pid,      [_]=Ops, Fail) ->
+    {test,is_pid,Fail,Ops};
+bif_to_test_1(is_port,     [_]=Ops, Fail) ->
+    {test,is_port,Fail,Ops};
+bif_to_test_1(is_reference, [_]=Ops, Fail) ->
+    {test,is_reference,Fail,Ops};
+bif_to_test_1(is_tuple,    [_]=Ops, Fail) ->
+    {test,is_tuple,Fail,Ops};
+bif_to_test_1('=<', [A,B], Fail) ->
+    {test,is_ge,Fail,[B,A]};
+bif_to_test_1('>', [A,B], Fail) ->
+    {test,is_lt,Fail,[B,A]};
+bif_to_test_1('<', [_,_]=Ops, Fail) ->
+    {test,is_lt,Fail,Ops};
+bif_to_test_1('>=', [_,_]=Ops, Fail) ->
+    {test,is_ge,Fail,Ops};
+bif_to_test_1('==', [C,A], Fail) when ?IS_LITERAL(C) ->
+    {test,is_eq,Fail,[A,C]};
+bif_to_test_1('==', [_,_]=Ops, Fail) ->
+    {test,is_eq,Fail,Ops};
+bif_to_test_1('/=', [C,A], Fail) when ?IS_LITERAL(C) ->
+    {test,is_ne,Fail,[A,C]};
+bif_to_test_1('/=', [_,_]=Ops, Fail) ->
+    {test,is_ne,Fail,Ops};
+bif_to_test_1('=:=', [C,A], Fail) when ?IS_LITERAL(C) ->
+    {test,is_eq_exact,Fail,[A,C]};
+bif_to_test_1('=:=', [_,_]=Ops, Fail) ->
+    {test,is_eq_exact,Fail,Ops};
+bif_to_test_1('=/=', [C,A], Fail) when ?IS_LITERAL(C) ->
+    {test,is_ne_exact,Fail,[A,C]};
+bif_to_test_1('=/=', [_,_]=Ops, Fail) ->
+    {test,is_ne_exact,Fail,Ops}.
 
 opt_call_moves(Is0, Arity) ->
     {Moves0,Is} = splitwith(fun({move,_,_}) -> true;
+                               ({kill,_}) -> true;
                                (_) -> false
                             end, Is0),
     Moves = opt_call_moves_1(Moves0, Arity),
     Moves ++ Is.
 
+opt_call_moves_1([{move,Src,{x,_}=Tmp}=M1|[{kill,_}|_]=Is], Arity) ->
+    %% There could be a {move,Tmp,{x,0}} instruction after the
+    %% kill/1 instructions (moved to there by opt_move_to_x0/1).
+    case splitwith(fun({kill,_}) -> true;
+                      (_) -> false
+                   end, Is) of
+        {Kills,[{move,{x,_}=Tmp,{x,0}}=M2]} ->
+            %% The two move/2 instructions (M1 and M2) can be combined
+            %% to one. The question is, though, is it safe to place
+            %% them after the kill/1 instructions?
+            case is_killed(Src, Kills, Arity) of
+                true ->
+                    %% Src (a Y register) is killed by one of the
+                    %% kill/1 instructions. Thus M1 and M2
+                    %% must be placed before the kill/1 instructions
+                    %% (essentially undoing what opt_move_to_x0/1
+                    %% did, which turned out to be a pessimization
+                    %% in this case).
+                    opt_call_moves_1([M1,M2|Kills], Arity);
+                false ->
+                    %% Src is not killed by any of the kill/1
+                    %% instructions. Thus it is safe to place
+                    %% M1 and M2 after the kill/1 instructions.
+                    opt_call_moves_1(Kills++[M1,M2], Arity)
+            end;
+        {_,_} ->
+            [M1|Is]
+    end;
 opt_call_moves_1([{move,Src,{x,_}=Tmp}=M1,{move,Tmp,Dst}=M2|Is], Arity) ->
     case is_killed(Tmp, Is, Arity) of
         true ->
@@ -1239,6 +1357,10 @@ opt_call_moves_1([M|Ms], Arity) ->
     [M|opt_call_moves_1(Ms, Arity)];
 opt_call_moves_1([], _Arity) -> [].
 
+is_killed(Y, [{kill,Y}|_], _) ->
+    true;
+is_killed(R, [{kill,_}|Is], Arity) ->
+    is_killed(R, Is, Arity);
 is_killed(R, [{move,R,_}|_], _) ->
     false;
 is_killed(R, [{move,_,R}|_], _) ->
@@ -1246,7 +1368,9 @@ is_killed(R, [{move,_,R}|_], _) ->
 is_killed(R, [{move,_,_}|Is], Arity) ->
     is_killed(R, Is, Arity);
 is_killed({x,X}, [], Arity) ->
-    X >= Arity.
+    X >= Arity;
+is_killed({y,_}, [], _) ->
+    false.
 
 cg_alloc(#cg_alloc{stack=none,words=#need{h=0,f=0}}, _St) ->
     [];
@@ -1527,13 +1651,13 @@ cg_bs_put(Fail, [{atom,Type},{literal,Flags}|Args]) ->
             [{Op,Fail,{field_flags,Flags},Src}]
     end.
 
-cg_bs_init(Dst, Size0, Unit, Live, Fail) ->
+cg_bs_init(Dst, Size0, Alloc, Unit, Live, Fail) ->
     Op = case Unit of
              1 -> bs_init_bits;
              8 -> bs_init2
          end,
     Size = cg_bs_init_size(Size0),
-    [{Op,Fail,Size,0,Live,{field_flags,[]},Dst}].
+    [{Op,Fail,Size,Alloc,Live,{field_flags,[]},Dst}].
 
 cg_bs_init_size({x,_}=R) -> R;
 cg_bs_init_size({y,_}=R) -> R;
@@ -1652,12 +1776,41 @@ phi_copies([#b_set{dst=Dst,args=PhiArgs}|Sets], L) ->
     [#cg_set{op=copy,dst=Dst,args=CopyArgs}|phi_copies(Sets, L)];
 phi_copies([], _) -> [].
 
+%% opt_move_to_x0([Instruction]) -> [Instruction].
+%%  Simple peep-hole optimization to move a {move,Any,{x,0}} past
+%%  any kill up to the next call instruction. (To give the loader
+%%  an opportunity to combine the 'move' and the 'call' instructions.)
+
+opt_move_to_x0(Moves) ->
+    opt_move_to_x0(Moves, []).
+
+opt_move_to_x0([{move,_,{x,0}}=I|Is0], Acc0) ->
+    case move_past_kill(Is0, I, Acc0) of
+       impossible -> opt_move_to_x0(Is0, [I|Acc0]);
+       {Is,Acc} -> opt_move_to_x0(Is, Acc)
+    end;
+opt_move_to_x0([I|Is], Acc) ->
+    opt_move_to_x0(Is, [I|Acc]);
+opt_move_to_x0([], Acc) -> reverse(Acc).
+
+move_past_kill([{kill,Src}|_], {move,Src,_}, _) ->
+    impossible;
+move_past_kill([{kill,_}=I|Is], Move, Acc) ->
+    move_past_kill(Is, Move, [I|Acc]);
+move_past_kill(Is, Move, Acc) ->
+    {Is,[Move|Acc]}.
+
 %% setup_args(Args, Anno, Context) -> [Instruction].
 %% setup_args(Args) -> [Instruction].
 %%  Set up X registers for a call.
 
 setup_args(Args, Anno, none, St) ->
-    setup_args(Args) ++ kill_yregs(Anno, St);
+    case {setup_args(Args),kill_yregs(Anno, St)} of
+        {Moves,[]} ->
+            Moves;
+        {Moves,Kills} ->
+            opt_move_to_x0(Moves ++ Kills)
+    end;
 setup_args(Args, _, _, _) ->
     setup_args(Args).
 
diff --git a/lib/compiler/src/beam_ssa_pre_codegen.erl b/lib/compiler/src/beam_ssa_pre_codegen.erl
index 36137ef046..19a938c897 100644
--- a/lib/compiler/src/beam_ssa_pre_codegen.erl
+++ b/lib/compiler/src/beam_ssa_pre_codegen.erl
@@ -652,21 +652,24 @@ sanitize([], Count, Blocks0, Values) ->
          false -> remove_unreachable(Ls, Blocks, Reachable, [])
      end,Count}.
 
-sanitize_is([#b_set{op=get_map_element,
-                    args=[#b_literal{}=Map,Key]}=I0|Is],
-            Count0, Values, _Changed, Acc) ->
-    {MapVar,Count} = new_var('@ssa_map', Count0),
-    I = I0#b_set{args=[MapVar,Key]},
-    Copy = #b_set{op=copy,dst=MapVar,args=[Map]},
-    sanitize_is(Is, Count, Values, true, [I,Copy|Acc]);
+sanitize_is([#b_set{op=get_map_element,args=Args0}=I0|Is],
+            Count0, Values, Changed, Acc) ->
+    case sanitize_args(Args0, Values) of
+        [#b_literal{}=Map,Key] ->
+            %% Bind the literal map to a variable.
+            {MapVar,Count} = new_var('@ssa_map', Count0),
+            I = I0#b_set{args=[MapVar,Key]},
+            Copy = #b_set{op=copy,dst=MapVar,args=[Map]},
+            sanitize_is(Is, Count, Values, true, [I,Copy|Acc]);
+        [_,_]=Args0 ->
+            sanitize_is(Is, Count0, Values, Changed, [I0|Acc]);
+        [_,_]=Args ->
+            I = I0#b_set{args=Args},
+            sanitize_is(Is, Count0, Values, Changed, [I|Acc])
+    end;
 sanitize_is([#b_set{op=Op,dst=Dst,args=Args0}=I0|Is0],
-            Count, Values, Changed, Acc) ->
-    Args = map(fun(Var) ->
-                       case Values of
-                           #{Var:=New} -> New;
-                           #{} -> Var
-                       end
-               end, Args0),
+            Count, Values, Changed0, Acc) ->
+    Args = sanitize_args(Args0, Values),
     case sanitize_instr(Op, Args, I0) of
         {value,Value0} ->
             Value = #b_literal{val=Value0},
@@ -674,7 +677,9 @@ sanitize_is([#b_set{op=Op,dst=Dst,args=Args0}=I0|Is0],
         {ok,I} ->
             sanitize_is(Is0, Count, Values, true, [I|Acc]);
         ok ->
-            sanitize_is(Is0, Count, Values, Changed, [I0|Acc])
+            I = I0#b_set{args=Args},
+            Changed = Changed0 orelse Args =/= Args0,
+            sanitize_is(Is0, Count, Values, Changed, [I|Acc])
     end;
 sanitize_is([], Count, Values, Changed, Acc) ->
     case Changed of
@@ -684,6 +689,14 @@ sanitize_is([], Count, Values, Changed, Acc) ->
             no_change
     end.
 
+sanitize_args(Args, Values) ->
+    map(fun(Var) ->
+                case Values of
+                    #{Var:=New} -> New;
+                    #{} -> Var
+                end
+        end, Args).
+
 sanitize_instr({bif,Bif}, [#b_literal{val=Lit}], _I) ->
     case erl_bifs:is_pure(erlang, Bif, 1) of
         false ->
diff --git a/lib/compiler/src/beam_utils.erl b/lib/compiler/src/beam_utils.erl
index 626e041ea0..5156a04f6b 100644
--- a/lib/compiler/src/beam_utils.erl
+++ b/lib/compiler/src/beam_utils.erl
@@ -23,14 +23,12 @@
 -module(beam_utils).
 -export([is_killed/3,is_killed_at/3,is_not_used/3,
 	 empty_label_index/0,index_label/3,index_labels/1,replace_labels/4,
-	 code_at/2,bif_to_test/3,is_pure_test/1,
-	 combine_heap_needs/2,
-	 split_even/1
-        ]).
+	 code_at/2,is_pure_test/1,
+	 split_even/1]).
 
 -export_type([code_index/0,module_code/0,instruction/0]).
 
--import(lists, [flatmap/2,map/2,member/2,sort/1,reverse/1]).
+-import(lists, [map/2,member/2,sort/1,reverse/1]).
 
 -define(is_const(Val), (Val =:= nil orelse
                         element(1, Val) =:= integer orelse
@@ -38,7 +36,7 @@
                         element(1, Val) =:= atom orelse
                         element(1, Val) =:= literal)).
 
-%% instruction() describes all instructions that are used during optimzation
+%% instruction() describes all instructions that are used during optimization
 %% (from beam_a to beam_z).
 -type instruction() :: atom() | tuple().
 
@@ -158,44 +156,6 @@ code_at(L, Ll) ->
 replace_labels(Is, Acc, D, Fb) ->
     replace_labels_1(Is, Acc, D, Fb).
 
-%% bif_to_test(Bif, [Op], Fail) -> {test,Test,Fail,[Op]}
-%%  Convert a BIF to a test. Fail if not possible.
-
--spec bif_to_test(atom(), list(), fail()) -> test().
-
-bif_to_test(is_atom,     [_]=Ops, Fail) -> {test,is_atom,Fail,Ops};
-bif_to_test(is_boolean,  [_]=Ops, Fail) -> {test,is_boolean,Fail,Ops};
-bif_to_test(is_binary,   [_]=Ops, Fail) -> {test,is_binary,Fail,Ops};
-bif_to_test(is_bitstring,[_]=Ops, Fail) -> {test,is_bitstr,Fail,Ops};
-bif_to_test(is_float,    [_]=Ops, Fail) -> {test,is_float,Fail,Ops};
-bif_to_test(is_function, [_]=Ops, Fail) -> {test,is_function,Fail,Ops};
-bif_to_test(is_function, [_,_]=Ops, Fail) -> {test,is_function2,Fail,Ops};
-bif_to_test(is_integer,  [_]=Ops, Fail) -> {test,is_integer,Fail,Ops};
-bif_to_test(is_list,     [_]=Ops, Fail) -> {test,is_list,Fail,Ops};
-bif_to_test(is_map,      [_]=Ops, Fail) -> {test,is_map,Fail,Ops};
-bif_to_test(is_number,   [_]=Ops, Fail) -> {test,is_number,Fail,Ops};
-bif_to_test(is_pid,      [_]=Ops, Fail) -> {test,is_pid,Fail,Ops};
-bif_to_test(is_port,     [_]=Ops, Fail) -> {test,is_port,Fail,Ops};
-bif_to_test(is_reference, [_]=Ops, Fail) -> {test,is_reference,Fail,Ops};
-bif_to_test(is_tuple,    [_]=Ops, Fail)     -> {test,is_tuple,Fail,Ops};
-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('==', [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('=:=', [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};
-bif_to_test('=/=', [C,A], Fail) when ?is_const(C) ->
-    {test,is_ne_exact,Fail,[A,C]};
-bif_to_test('=/=', [_,_]=Ops, Fail) -> {test,is_ne_exact,Fail,Ops}.
-
-
 %% is_pure_test({test,Op,Fail,Ops}) -> true|false.
 %%  Return 'true' if the test instruction does not modify any
 %%  registers and/or bit syntax matching state.
@@ -218,19 +178,6 @@ is_pure_test({test,is_function2,_,[_,_]}) -> true;
 is_pure_test({test,Op,_,Ops}) -> 
     erl_internal:new_type_test(Op, length(Ops)).
 
-%% combine_heap_needs(HeapNeed1, HeapNeed2) -> HeapNeed
-%%  Combine the heap need for two allocation instructions.
-
--type heap_need_tag() :: 'floats' | 'words'.
--type heap_need() :: non_neg_integer() |
-                     {'alloc',[{heap_need_tag(),non_neg_integer()}]}.
--spec combine_heap_needs(heap_need(), heap_need()) -> heap_need().
-
-combine_heap_needs(H1, H2) when is_integer(H1), is_integer(H2) ->
-    H1 + H2;
-combine_heap_needs(H1, H2) ->
-    {alloc,combine_alloc_lists([H1,H2])}.
-
 %% split_even/1
 %% [1,2,3,4,5,6] -> {[1,3,5],[2,4,6]}
 
@@ -729,19 +676,6 @@ label(Old, D, Fb) ->
         _ -> Fb(Old)
     end.
 
-%% Help function for combine_heap_needs.
-
-combine_alloc_lists(Al0) ->
-    Al1 = flatmap(fun(Words) when is_integer(Words) ->
-                         [{words,Words}];
-                    ({alloc,List}) ->
-                         List
-                 end, Al0),
-    Al2 = sofs:relation(Al1),
-    Al3 = sofs:relation_to_family(Al2),
-    Al4 = sofs:to_external(Al3),
-    [{Tag,lists:sum(L)} || {Tag,L} <- Al4].
-
 %% live_opt/4.
 
 split_even([], Ss, Ds) ->
diff --git a/lib/compiler/src/beam_validator.erl b/lib/compiler/src/beam_validator.erl
index ca065295d6..7d908df3bf 100644
--- a/lib/compiler/src/beam_validator.erl
+++ b/lib/compiler/src/beam_validator.erl
@@ -479,16 +479,20 @@ valfun_1({try_case,Reg}, #vst{current=#st{ct=[Fail|Fails]}}=Vst0) ->
 	    error({bad_type,Type})
     end;
 valfun_1({get_list,Src,D1,D2}, Vst0) ->
+    assert_not_literal(Src),
     assert_type(cons, Src, Vst0),
     Vst = set_type_reg(term, Src, D1, Vst0),
     set_type_reg(term, Src, D2, Vst);
 valfun_1({get_hd,Src,Dst}, Vst) ->
+    assert_not_literal(Src),
     assert_type(cons, Src, Vst),
     set_type_reg(term, Src, Dst, Vst);
 valfun_1({get_tl,Src,Dst}, Vst) ->
+    assert_not_literal(Src),
     assert_type(cons, Src, Vst),
     set_type_reg(term, Src, Dst, Vst);
 valfun_1({get_tuple_element,Src,I,Dst}, Vst) ->
+    assert_not_literal(Src),
     assert_type({tuple_element,I+1}, Src, Vst),
     set_type_reg(term, Src, Dst, Vst);
 valfun_1({jump,{f,Lbl}}, Vst) ->
@@ -917,6 +921,7 @@ valfun_4(_, _) ->
     error(unknown_instruction).
 
 verify_get_map(Fail, Src, List, Vst0) ->
+    assert_not_literal(Src),                    %OTP 22.
     assert_type(map, Src, Vst0),
     Vst1 = foldl(fun(D, Vsti) ->
                          case is_reg_defined(D,Vsti) of
@@ -1466,6 +1471,10 @@ assert_term(Src, Vst) ->
     get_term_type(Src, Vst),
     ok.
 
+assert_not_literal({x,_}) -> ok;
+assert_not_literal({y,_}) -> ok;
+assert_not_literal(Literal) -> error({literal_not_allowed,Literal}).
+
 %% The possible types.
 %%
 %% First non-term types: