Merge branch 'egil/maps/variable-keys/OTP-12218'

* egil/maps/variable-keys/OTP-12218: (22 commits)
  compiler: Update test for Maps aliasing
  compiler: Properly support Map aliasing
  compiler: Refactor Map pairs aliasing
  compiler: Fix harmless need_heap error for Maps
  stdlib: Update Map tests
  stdlib: Use environment bindings for Maps keys in erl_eval matching
  debugger: Update Map tests
  compiler: Update Map tests
  compiler: Fix v3_core Maps pair chains
  compiler: Use expressions in core patterns
  compiler: Use variables in Map cerl inliner
  compiler: Reintroduce binary limit for Map keys
  compiler: Shameless v3_core hack for variables
  compiler: Use variables in Map beam assmebler
  compiler: Use variables in Map kernel pass
  compiler: Use variables in Map core pass
  compiler: Normalize unary ops on Maps key literals
  stdlib: Update Map tests
  stdlib: erl_lint Map key variables
  compiler: Maps are always patterns never values in matching
  ...

14 files changed, 405 insertions, 249 deletions

diff --git a/lib/compiler/src/beam_block.erl b/lib/compiler/src/beam_block.erl
index 7a30c68593..5626aa34ab 100644
--- a/lib/compiler/src/beam_block.erl
+++ b/lib/compiler/src/beam_block.erl
@@ -155,7 +155,8 @@ collect(remove_message)      -> {set,[],[],remove_message};
 collect({put_map,F,Op,S,D,R,{list,Puts}}) ->
     {set,[D],[S|Puts],{alloc,R,{put_map,Op,F}}};
 collect({get_map_elements,F,S,{list,Gets}}) ->
-    {set,Gets,[S],{get_map_elements,F}};
+    {Ss,Ds} = beam_utils:spliteven(Gets),
+    {set,Ds,[S|Ss],{get_map_elements,F}};
 collect({'catch',R,L})       -> {set,[R],[],{'catch',L}};
 collect(fclearerror)         -> {set,[],[],fclearerror};
 collect({fcheckerror,{f,0}}) -> {set,[],[],fcheckerror};
diff --git a/lib/compiler/src/beam_flatten.erl b/lib/compiler/src/beam_flatten.erl
index 46835bece1..05d067dc48 100644
--- a/lib/compiler/src/beam_flatten.erl
+++ b/lib/compiler/src/beam_flatten.erl
@@ -63,7 +63,8 @@ norm({set,[],[S,D],{set_tuple_element,I}}) -> {set_tuple_element,S,D,I};
 norm({set,[D1,D2],[S],get_list})          -> {get_list,S,D1,D2};
 norm({set,[D],[S|Puts],{alloc,R,{put_map,Op,F}}}) ->
     {put_map,F,Op,S,D,R,{list,Puts}};
-norm({set,Gets,[S],{get_map_elements,F}}) ->
+norm({set,Ds,[S|Ss],{get_map_elements,F}}) ->
+    Gets = beam_utils:joineven(Ss,Ds),
     {get_map_elements,F,S,{list,Gets}};
 norm({set,[],[],remove_message})   -> remove_message;
 norm({set,[],[],fclearerror}) -> fclearerror;
diff --git a/lib/compiler/src/beam_split.erl b/lib/compiler/src/beam_split.erl
index 688bba9a94..f5dba314ae 100644
--- a/lib/compiler/src/beam_split.erl
+++ b/lib/compiler/src/beam_split.erl
@@ -53,8 +53,9 @@ split_block([{set,[D],[S|Puts],{alloc,R,{put_map,Op,{f,Lbl}=Fail}}}|Is],
 	    Bl, Acc) when Lbl =/= 0 ->
     split_block(Is, [], [{put_map,Fail,Op,S,D,R,{list,Puts}}|
 			 make_block(Bl, Acc)]);
-split_block([{set,Gets,[S],{get_map_elements,{f,Lbl}=Fail}}|Is], Bl, Acc)
+split_block([{set,Ds,[S|Ss],{get_map_elements,{f,Lbl}=Fail}}|Is], Bl, Acc)
   when Lbl =/= 0 ->
+    Gets = beam_utils:joineven(Ss,Ds),
     split_block(Is, [], [{get_map_elements,Fail,S,{list,Gets}}|make_block(Bl, Acc)]);
 split_block([{set,[R],[],{'catch',L}}|Is], Bl, Acc) ->
     split_block(Is, [], [{'catch',R,L}|make_block(Bl, Acc)]);
diff --git a/lib/compiler/src/beam_utils.erl b/lib/compiler/src/beam_utils.erl
index 8ca368c167..e82ba82d38 100644
--- a/lib/compiler/src/beam_utils.erl
+++ b/lib/compiler/src/beam_utils.erl
@@ -26,6 +26,8 @@
 	 code_at/2,bif_to_test/3,is_pure_test/1,
 	 live_opt/1,delete_live_annos/1,combine_heap_needs/2]).
 
+-export([joineven/2,spliteven/1]).
+
 -import(lists, [member/2,sort/1,reverse/1,splitwith/2]).
 
 -record(live,
@@ -832,3 +834,15 @@ x_live([_|Rs], Regs) -> x_live(Rs, Regs);
 x_live([], Regs) -> Regs.
 
 is_live(X, Regs) -> ((Regs bsr X) band 1) =:= 1.
+
+%% spliteven/1
+%% [1,2,3,4,5,6] -> {[1,3,5],[2,4,6]}
+spliteven(Rs) -> spliteven(Rs,[],[]).
+spliteven([],Ss,Ds) -> {reverse(Ss),reverse(Ds)};
+spliteven([S,D|Rs],Ss,Ds) ->
+    spliteven(Rs,[S|Ss],[D|Ds]).
+
+%% joineven/1
+%% {[1,3,5],[2,4,6]} -> [1,2,3,4,5,6]
+joineven([],[]) -> [];
+joineven([S|Ss],[D|Ds]) -> [S,D|joineven(Ss,Ds)].
diff --git a/lib/compiler/src/beam_validator.erl b/lib/compiler/src/beam_validator.erl
index 9d5563d13b..0acc7a227f 100644
--- a/lib/compiler/src/beam_validator.erl
+++ b/lib/compiler/src/beam_validator.erl
@@ -1123,7 +1123,9 @@ assert_freg_set(Fr, _) -> error({bad_source,Fr}).
 %%% Maps
 
 %% ensure that a list of literals has a strict
-%% ascending term order (also meaning unique literals)
+%% ascending term order (also meaning unique literals).
+%% Single item lists may have registers.
+assert_strict_literal_termorder([_]) -> ok;
 assert_strict_literal_termorder(Ls) ->
     Vs = lists:map(fun (L) -> get_literal(L) end, Ls),
     case check_strict_value_termorder(Vs) of
diff --git a/lib/compiler/src/cerl.erl b/lib/compiler/src/cerl.erl
index 9d6768b157..7a2c3d70de 100644
--- a/lib/compiler/src/cerl.erl
+++ b/lib/compiler/src/cerl.erl
@@ -3063,10 +3063,12 @@ pat_vars(Node, Vs) ->
 	map ->
 	    pat_list_vars(map_es(Node), Vs);
 	map_pair ->
-	    pat_list_vars([map_pair_op(Node),map_pair_key(Node),map_pair_val(Node)],Vs);
+	    %% map_pair_key is not a pattern var, excluded
+	    pat_list_vars([map_pair_op(Node),map_pair_val(Node)],Vs);
 	binary ->
 	    pat_list_vars(binary_segments(Node), Vs);
 	bitstr ->
+	    %% bitstr_size is not a pattern var, excluded
 	    pat_vars(bitstr_val(Node), Vs);
 	alias ->
 	    pat_vars(alias_pat(Node), [alias_var(Node) | Vs])
diff --git a/lib/compiler/src/cerl_inline.erl b/lib/compiler/src/cerl_inline.erl
index 75740e8b9d..f8489a800b 100644
--- a/lib/compiler/src/cerl_inline.erl
+++ b/lib/compiler/src/cerl_inline.erl
@@ -1341,23 +1341,23 @@ i_bitstr(E, Ren, Env, S) ->
     S3 = count_size(weight(bitstr), S2),
     {update_c_bitstr(E, Val, Size, Unit, Type, Flags), S3}.
 
-i_map(E, Ctx, Ren, Env, S) ->
+i_map(E, Ctx, Ren, Env, S0) ->
     %% Visit the segments for value.
-    {M1, S1} = i(map_arg(E), value, Ren, Env, S),
+    {M1, S1} = i(map_arg(E), value, Ren, Env, S0),
     {Es, S2} = mapfoldl(fun (E, S) ->
 		i_map_pair(E, Ctx, Ren, Env, S)
 	end, S1, map_es(E)),
     S3 = count_size(weight(map), S2),
     {update_c_map(E, M1,Es), S3}.
 
-i_map_pair(E, Ctx, Ren, Env, S) ->
-    %% It is not necessary to visit the Op and Key fields,
-    %% since these are always literals.
-    {Val, S1} = i(map_pair_val(E), Ctx, Ren, Env, S),
+i_map_pair(E, Ctx, Ren, Env, S0) ->
+    %% It is not necessary to visit the Op field
+    %% since it is always a literal.
+    {Key, S1} = i(map_pair_key(E), value, Ren, Env, S0),
+    {Val, S2} = i(map_pair_val(E), Ctx, Ren, Env, S1),
     Op = map_pair_op(E),
-    Key = map_pair_key(E),
-    S2 = count_size(weight(map_pair), S1),
-    {update_c_map_pair(E, Op, Key, Val), S2}.
+    S3 = count_size(weight(map_pair), S2),
+    {update_c_map_pair(E, Op, Key, Val), S3}.
 
 
 %% This is a simplified version of `i_pattern', for lists of parameter
@@ -1420,15 +1420,11 @@ i_pattern(E, Ren, Env, Ren0, Env0, S) ->
 	    S2 = count_size(weight(binary), S1),
 	    {update_c_binary(E, Es), S2};
 	map ->
-	    %% map patterns should not have args
-	    M = map_arg(E),
-
 	    {Es, S1} = mapfoldl(fun (E, S) ->
 			i_map_pair_pattern(E, Ren, Env, Ren0, Env0, S)
-		end,
-		S, map_es(E)),
+		end, S, map_es(E)),
 	    S2 = count_size(weight(map), S1),
-	    {update_c_map(E, M, Es), S2};
+	    {update_c_map(E, map_arg(E), Es), S2};
 	_ ->
 	    case is_literal(E) of
 		true ->
@@ -1464,12 +1460,12 @@ i_bitstr_pattern(E, Ren, Env, Ren0, Env0, S) ->
 
 i_map_pair_pattern(E, Ren, Env, Ren0, Env0, S) ->
     %% It is not necessary to visit the Op it is always a literal.
-    %% Same goes for Key
-    {Val, S1} = i_pattern(map_pair_val(E), Ren, Env, Ren0, Env0, S),
+    %% Key is an expression
+    {Key, S1} = i(map_pair_key(E), value, Ren0, Env0, S),
+    {Val, S2} = i_pattern(map_pair_val(E), Ren, Env, Ren0, Env0, S1),
     Op = map_pair_op(E), %% should be 'exact' literal
-    Key  = map_pair_key(E),
-    S2 = count_size(weight(map_pair), S1),
-    {update_c_map_pair(E, Op, Key, Val), S2}.
+    S3 = count_size(weight(map_pair), S2),
+    {update_c_map_pair(E, Op, Key, Val), S3}.
 
 
 %% ---------------------------------------------------------------------
diff --git a/lib/compiler/src/cerl_trees.erl b/lib/compiler/src/cerl_trees.erl
index e53bdd4efb..b93da8e97f 100644
--- a/lib/compiler/src/cerl_trees.erl
+++ b/lib/compiler/src/cerl_trees.erl
@@ -520,9 +520,9 @@ variables(T, S) ->
 	tuple ->
 	    vars_in_list(tuple_es(T), S);
 	map ->
-	    vars_in_list(map_es(T), S);
+	    vars_in_list([map_arg(T)|map_es(T)], S);
 	map_pair ->
-	    vars_in_list([map_pair_op(T),map_pair_key(T), map_pair_val(T)], S);
+	    vars_in_list([map_pair_op(T),map_pair_key(T),map_pair_val(T)], S);
 	'let' ->
 	    Vs = variables(let_body(T), S),
 	    Vs1 = var_list_names(let_vars(T)),
diff --git a/lib/compiler/src/core_pp.erl b/lib/compiler/src/core_pp.erl
index 83412ecdd7..03801a9b6d 100644
--- a/lib/compiler/src/core_pp.erl
+++ b/lib/compiler/src/core_pp.erl
@@ -125,8 +125,8 @@ format_1(#c_literal{anno=A,val=M},Ctxt) when is_map(M) ->
 	_ -> assoc
     end,
     Cpairs = [#c_map_pair{op=#c_literal{val=Op},
-			  key=#c_literal{val=V},
-			  val=#c_literal{val=K}} || {K,V} <- Pairs],
+			  key=#c_literal{val=K},
+			  val=#c_literal{val=V}} || {K,V} <- Pairs],
 	format_1(#c_map{anno=A,arg=#c_literal{val=#{}},es=Cpairs},Ctxt);
 format_1(#c_var{name={I,A}}, _) ->
     [core_atom(I),$/,integer_to_list(A)];
diff --git a/lib/compiler/src/sys_pre_expand.erl b/lib/compiler/src/sys_pre_expand.erl
index 6410b73941..f99307c865 100644
--- a/lib/compiler/src/sys_pre_expand.erl
+++ b/lib/compiler/src/sys_pre_expand.erl
@@ -262,9 +262,18 @@ pattern({map,Line,Ps}, St0) ->
     {TPs,St1} = pattern_list(Ps, St0),
     {{map,Line,TPs},St1};
 pattern({map_field_exact,Line,K0,V0}, St0) ->
-    {K,St1} = expr(K0, St0),
+    %% Key should be treated as an expression
+    %% but since expressions are not allowed yet,
+    %% process it through pattern .. and handle assoc
+    %% (normalise unary op integer -> integer)
+    {K,St1} = pattern(K0, St0),
     {V,St2} = pattern(V0, St1),
     {{map_field_exact,Line,K,V},St2};
+pattern({map_field_assoc,Line,K0,V0}, St0) ->
+    %% when keys are Maps
+    {K,St1} = pattern(K0, St0),
+    {V,St2} = pattern(V0, St1),
+    {{map_field_assoc,Line,K,V},St2};
 %%pattern({struct,Line,Tag,Ps}, St0) ->
 %%    {TPs,TPsvs,St1} = pattern_list(Ps, St0),
 %%    {{tuple,Line,[{atom,Line,Tag}|TPs]},TPsvs,St1};
diff --git a/lib/compiler/src/v3_codegen.erl b/lib/compiler/src/v3_codegen.erl
index 47a357c23d..8c1a0c08ac 100644
--- a/lib/compiler/src/v3_codegen.erl
+++ b/lib/compiler/src/v3_codegen.erl
@@ -210,7 +210,7 @@ need_heap_0([], H, Acc) ->
 
 need_heap_1(#l{ke={set,_,{binary,_}},i=I}, H) ->
     {need_heap_need(I, H),0};
-need_heap_1(#l{ke={set,_,{map,_,_}},i=I}, H) ->
+need_heap_1(#l{ke={set,_,{map,_,_,_}},i=I}, H) ->
     {need_heap_need(I, H),0};
 need_heap_1(#l{ke={set,_,Val}}, H) ->
     %% Just pass through adding to needed heap.
@@ -643,10 +643,6 @@ select_val_cg(tuple, R, [Arity,{f,Lbl}], Tf, Vf, [{label,Lbl}|Sis]) ->
     [{test,is_tuple,{f,Tf},[R]},{test,test_arity,{f,Vf},[R,Arity]}|Sis];
 select_val_cg(tuple, R, Vls, Tf, Vf, Sis) ->
     [{test,is_tuple,{f,Tf},[R]},{select_tuple_arity,R,{f,Vf},{list,Vls}}|Sis];
-select_val_cg(map, R, [_Val,{f,Lbl}], Fail, Fail, [{label,Lbl}|Sis]) ->
-    [{test,is_map,{f,Fail},[R]}|Sis];
-select_val_cg(map, R, [_Val,{f,Lbl}|_], Tf, _Vf, [{label,Lbl}|Sis]) ->
-    [{test,is_map,{f,Tf},[R]}|Sis];
 select_val_cg(Type, R, [Val, {f,Lbl}], Fail, Fail, [{label,Lbl}|Sis]) ->
     [{test,is_eq_exact,{f,Fail},[R,{Type,Val}]}|Sis];
 select_val_cg(Type, R, [Val, {f,Lbl}], Tf, Vf, [{label,Lbl}|Sis]) ->
@@ -947,27 +943,34 @@ select_extract_map(Src, Vs, Fail, I, Vdb, Bef, St) ->
     %% Assume keys are term-sorted
     Rsrc = fetch_var(Src, Bef),
 
-    {{HasKs,GetVs},Aft} = lists:foldr(fun
-	    ({map_pair,Key,{var,V}},{{HasKsi,GetVsi},Int0}) ->
+    {{HasKs,GetVs,HasVarKs,GetVarVs},Aft} = lists:foldr(fun
+	    ({map_pair,{var,K},{var,V}},{{HasKsi,GetVsi,HasVarVsi,GetVarVsi},Int0}) ->
 		case vdb_find(V, Vdb) of
 		    {V,_,L} when L =< I ->
-			{{[Key|HasKsi],GetVsi},Int0};
+			RK = fetch_var(K,Int0),
+			{{HasKsi,GetVsi,[RK|HasVarVsi],GetVarVsi},Int0};
 		    _Other ->
 			Reg1 = put_reg(V, Int0#sr.reg),
 			Int1 = Int0#sr{reg=Reg1},
-			{{HasKsi,[Key,fetch_reg(V, Reg1)|GetVsi]},Int1}
+			RK = fetch_var(K,Int0),
+			RV = fetch_reg(V,Reg1),
+			{{HasKsi,GetVsi,HasVarVsi,[[RK,RV]|GetVarVsi]},Int1}
+		end;
+	    ({map_pair,Key,{var,V}},{{HasKsi,GetVsi,HasVarVsi,GetVarVsi},Int0}) ->
+		case vdb_find(V, Vdb) of
+		    {V,_,L} when L =< I ->
+			{{[Key|HasKsi],GetVsi,HasVarVsi,GetVarVsi},Int0};
+		    _Other ->
+			Reg1 = put_reg(V, Int0#sr.reg),
+			Int1 = Int0#sr{reg=Reg1},
+			{{HasKsi,[Key,fetch_reg(V, Reg1)|GetVsi],HasVarVsi,GetVarVsi},Int1}
 		end
-	end, {{[],[]},Bef}, Vs),
-
-    Code = case {HasKs,GetVs} of
-	{HasKs,[]} ->
-	    [{test,has_map_fields,{f,Fail},Rsrc,{list,HasKs}}];
-	{[],GetVs} ->
-	    [{get_map_elements,   {f,Fail},Rsrc,{list,GetVs}}];
-	{HasKs,GetVs} ->
-	    [{test,has_map_fields,{f,Fail},Rsrc,{list,HasKs}},
-	     {get_map_elements,   {f,Fail},Rsrc,{list,GetVs}}]
-    end,
+	end, {{[],[],[],[]},Bef}, Vs),
+
+    Code = [{test,has_map_fields,{f,Fail},Rsrc,{list,HasKs}} || HasKs =/= []] ++
+	   [{test,has_map_fields,{f,Fail},Rsrc,{list,[K]}}   || K <- HasVarKs] ++
+	   [{get_map_elements,   {f,Fail},Rsrc,{list,GetVs}} || GetVs =/= []] ++
+	   [{get_map_elements,   {f,Fail},Rsrc,{list,[K,V]}} || [K,V] <- GetVarVs],
     {Code, Aft, St}.
 
 
@@ -1504,9 +1507,39 @@ set_cg([{var,R}], {binary,Segs}, Le, Vdb, Bef,
     %% Now generate the complete code for constructing the binary.
     Code = cg_binary(PutCode, Target, Temp, Fail, MaxRegs, Le#l.a),
     {Sis++Code,Aft,St};
+% Map single variable key
+set_cg([{var,R}], {map,Op,Map,[{map_pair,{var,_}=K,V}]}, Le, Vdb, Bef,
+       #cg{in_catch=InCatch,bfail=Bfail}=St) ->
+
+    Fail = {f,Bfail},
+    {Sis,Int0} =
+	case InCatch of
+	    true -> adjust_stack(Bef, Le#l.i, Le#l.i+1, Vdb);
+	    false -> {[],Bef}
+	end,
+    SrcReg = cg_reg_arg(Map,Int0),
+    Line = line(Le#l.a),
+
+    List = [cg_reg_arg(K,Int0),cg_reg_arg(V,Int0)],
+
+    Live = max_reg(Bef#sr.reg),
+    Int1 = Int0#sr{reg=put_reg(R, Int0#sr.reg)},
+    Aft = clear_dead(Int1, Le#l.i, Vdb),
+    Target = fetch_reg(R, Int1#sr.reg),
+
+    I = case Op of
+	assoc -> put_map_assoc;
+	exact -> put_map_exact
+    end,
+    {Sis++[Line]++[{I,Fail,SrcReg,Target,Live,{list,List}}],Aft,St};
+
+% Map (possibly) multiple literal keys
 set_cg([{var,R}], {map,Op,Map,Es}, Le, Vdb, Bef,
        #cg{in_catch=InCatch,bfail=Bfail}=St) ->
 
+    %% assert key literals
+    [] = [Var||{map_pair,{var,_}=Var,_} <- Es],
+
     Fail = {f,Bfail},
     {Sis,Int0} =
 	case InCatch of
diff --git a/lib/compiler/src/v3_core.erl b/lib/compiler/src/v3_core.erl
index 83cf76f241..3d9fc3a609 100644
--- a/lib/compiler/src/v3_core.erl
+++ b/lib/compiler/src/v3_core.erl
@@ -78,7 +78,7 @@
 -import(ordsets, [add_element/2,del_element/2,is_element/2,
 		  union/1,union/2,intersection/2,subtract/2]).
 -import(cerl, [ann_c_cons/3,ann_c_cons_skel/3,ann_c_tuple/2,c_tuple/1,
-	       ann_c_map/2, ann_c_map/3]).
+	       ann_c_map/3]).
 
 -include("core_parse.hrl").
 
@@ -169,60 +169,81 @@ form({attribute,_,_,_}=F, {Fs,As,Ws,File}, _Opts) ->
 attribute({attribute,Line,Name,Val}) ->
     {#c_literal{val=Name, anno=[Line]}, #c_literal{val=Val, anno=[Line]}}.
 
+%% function_dump(module_info,_,_,_) -> ok;
+%% function_dump(Name,Arity,Format,Terms) ->
+%%     io:format("~w/~w " ++ Format,[Name,Arity]++Terms),
+%%     ok.
+
 function({function,_,Name,Arity,Cs0}, Ws0, File, Opts) ->
-    %%ok = io:fwrite("~p - ", [{Name,Arity}]),
     St0 = #core{vcount=0,opts=Opts,ws=Ws0,file=[{file,File}]},
     {B0,St1} = body(Cs0, Name, Arity, St0),
-    %%ok = io:fwrite("1", []),
-    %%ok = io:fwrite("~w:~p~n", [?LINE,B0]),
+    %% ok = function_dump(Name,Arity,"body:~n~p~n",[B0]),
     {B1,St2} = ubody(B0, St1),
-    %%ok = io:fwrite("2", []),
-    %%ok = io:fwrite("~w:~p~n", [?LINE,B1]),
+    %% ok = function_dump(Name,Arity,"ubody:~n~p~n",[B1]),
     {B2,#core{ws=Ws}} = cbody(B1, St2),
-    %%ok = io:fwrite("3~n", []),
-    %%ok = io:fwrite("~w:~p~n", [?LINE,B2]),
+    %% ok = function_dump(Name,Arity,"cbody:~n~p~n",[B2]),
     {{#c_var{name={Name,Arity}},B2},Ws}.
 
 body(Cs0, Name, Arity, St0) ->
     Anno = lineno_anno(element(2, hd(Cs0)), St0),
     {Args,St1} = new_vars(Anno, Arity, St0),
-    {Cs1,St2} = clauses(Cs0, St1),
-    {Ps,St3} = new_vars(Arity, St2),    %Need new variables here
-    Fc = function_clause(Ps, Anno, {Name,Arity}),
-    {#ifun{anno=#a{anno=Anno},id=[],vars=Args,clauses=Cs1,fc=Fc},St3}.
+    case clauses(Cs0, St1) of
+	{Cs1,[],St2} ->
+	    {Ps,St3} = new_vars(Arity, St2),    %Need new variables here
+	    Fc = function_clause(Ps, Anno, {Name,Arity}),
+	    {#ifun{anno=#a{anno=Anno},id=[],vars=Args,clauses=Cs1,fc=Fc},St3};
+	{Cs1,Eps,St2} ->
+	    %% We have pre-expressions from patterns and
+	    %% these needs to be letified before matching
+	    %% since only bound variables are allowed
+	    AnnoGen = #a{anno=[compiler_generated]},
+	    {Ps1,St3} = new_vars(Arity, St2),    %Need new variables here
+	    Fc1 = function_clause(Ps1, Anno, {Name,Arity}),
+	    {Ps2,St4} = new_vars(Arity, St3),    %Need new variables here
+	    Fc2 = function_clause(Ps2, Anno, {Name,Arity}),
+	    Case = #icase{anno=AnnoGen,args=Args,
+			  clauses=Cs1,
+			  fc=Fc2},
+	    {#ifun{anno=#a{anno=Anno},id=[],vars=Args,
+		   clauses=[#iclause{anno=AnnoGen,pats=Ps1,
+				     guard=[#c_literal{val=true}],
+				     body=Eps ++ [Case]}],
+		   fc=Fc1},St4}
+    end.
 
 %% clause(Clause, State) -> {Cclause,State} | noclause.
 %% clauses([Clause], State) -> {[Cclause],State}.
 %%  Convert clauses.  Trap bad pattern aliases and remove clause from
 %%  clause list.
 
-clauses([C0|Cs0], St0) ->
+clauses([C0|Cs0],St0) ->
     case clause(C0, St0) of
-	{noclause,St} -> clauses(Cs0, St);
-	{C,St1} ->
-	    {Cs,St2} = clauses(Cs0, St1),
-	    {[C|Cs],St2}
+	{noclause,_,St} -> clauses(Cs0,St);
+	{C,Eps1,St1} ->
+	    {Cs,Eps2,St2} = clauses(Cs0, St1),
+	    {[C|Cs],Eps1++Eps2,St2}
     end;
-clauses([], St) -> {[],St}.
+clauses([],St) -> {[],[],St}.
 
 clause({clause,Lc,H0,G0,B0}, St0) ->
     try head(H0, St0) of
-	H1 ->
-	    {G1,St1} = guard(G0, St0),
-	    {B1,St2} = exprs(B0, St1),
-            Anno = lineno_anno(Lc, St2),
-	    {#iclause{anno=#a{anno=Anno},pats=H1,guard=G1,body=B1},St2}
+	{H1,Eps,St1} ->
+	    {G1,St2} = guard(G0, St1),
+	    {B1,St3} = exprs(B0, St2),
+            Anno = lineno_anno(Lc, St3),
+	    {#iclause{anno=#a{anno=Anno},pats=H1,guard=G1,body=B1},Eps,St3}
     catch
 	throw:nomatch ->
 	    St = add_warning(Lc, nomatch, St0),
-	    {noclause,St}			%Bad pattern
+	    {noclause,[],St}			%Bad pattern
     end.
 
 clause_arity({clause,_,H0,_,_}) -> length(H0).
 
-%% head([P], State) -> [P].
+%% head([P], State) -> {[P],[Cexpr],State}.
 
-head(Ps, St) -> pattern_list(Ps, St).
+head(Ps, St) ->
+    pattern_list(Ps, St).
 
 %% guard([Expr], State) -> {[Cexpr],State}.
 %%  Build an explict and/or tree of guard alternatives, then traverse
@@ -514,22 +535,7 @@ expr({tuple,L,Es0}, St0) ->
     A = record_anno(L, St1),
     {annotate_tuple(A, Es1, St1),Eps,St1};
 expr({map,L,Es0}, St0) ->
-    % erl_lint should make sure only #{ K => V } are allowed
-    % in map construction.
-    try map_pair_list(Es0, St0) of
-	{Es1,Eps,St1} ->
-	    A = lineno_anno(L, St1),
-	    {ann_c_map(A,Es1),Eps,St1}
-    catch
-	throw:{bad_map,Warning} ->
-	    St = add_warning(L, Warning, St0),
-	    LineAnno = lineno_anno(L, St),
-	    As = [#c_literal{anno=LineAnno,val=badarg}],
-	    {#icall{anno=#a{anno=LineAnno},	%Must have an #a{}
-		    module=#c_literal{anno=LineAnno,val=erlang},
-		    name=#c_literal{anno=LineAnno,val=error},
-		    args=As},[],St}
-    end;
+    map_build_pair_chain(#c_literal{val=#{}},Es0,lineno_anno(L,St0),St0);
 expr({map,L,M0,Es0}, St0) ->
     try expr_map(M0,Es0,lineno_anno(L, St0),St0) of
 	{_,_,_}=Res -> Res
@@ -562,26 +568,26 @@ expr({block,_,Es0}, St0) ->
     {E1,Eps,St2} = expr(last(Es0), St1),
     {E1,Es1 ++ Eps,St2};
 expr({'if',L,Cs0}, St0) ->
-    {Cs1,St1} = clauses(Cs0, St0),
+    {Cs1,Ceps,St1} = clauses(Cs0, St0),
     Lanno = lineno_anno(L, St1),
     Fc = fail_clause([], Lanno, #c_literal{val=if_clause}),
-    {#icase{anno=#a{anno=Lanno},args=[],clauses=Cs1,fc=Fc},[],St1};
+    {#icase{anno=#a{anno=Lanno},args=[],clauses=Cs1,fc=Fc},Ceps,St1};
 expr({'case',L,E0,Cs0}, St0) ->
     {E1,Eps,St1} = novars(E0, St0),
-    {Cs1,St2} = clauses(Cs0, St1),
+    {Cs1,Ceps,St2} = clauses(Cs0, St1),
     {Fpat,St3} = new_var(St2),
     Lanno = lineno_anno(L, St2),
     Fc = fail_clause([Fpat], Lanno, c_tuple([#c_literal{val=case_clause},Fpat])),
-    {#icase{anno=#a{anno=Lanno},args=[E1],clauses=Cs1,fc=Fc},Eps,St3};
+    {#icase{anno=#a{anno=Lanno},args=[E1],clauses=Cs1,fc=Fc},Eps++Ceps,St3};
 expr({'receive',L,Cs0}, St0) ->
-    {Cs1,St1} = clauses(Cs0, St0),
-    {#ireceive1{anno=#a{anno=lineno_anno(L, St1)},clauses=Cs1}, [], St1};
+    {Cs1,Ceps,St1} = clauses(Cs0, St0),
+    {#ireceive1{anno=#a{anno=lineno_anno(L, St1)},clauses=Cs1},Ceps, St1};
 expr({'receive',L,Cs0,Te0,Tes0}, St0) ->
     {Te1,Teps,St1} = novars(Te0, St0),
     {Tes1,St2} = exprs(Tes0, St1),
-    {Cs1,St3} = clauses(Cs0, St2),
+    {Cs1,Ceps,St3} = clauses(Cs0, St2),
     {#ireceive2{anno=#a{anno=lineno_anno(L, St3)},
-		clauses=Cs1,timeout=Te1,action=Tes1},Teps,St3};
+		clauses=Cs1,timeout=Te1,action=Tes1},Teps++Ceps,St3};
 expr({'try',L,Es0,[],Ecs,[]}, St0) ->
     %% 'try ... catch ... end'
     {Es1,St1} = exprs(Es0, St0),
@@ -595,7 +601,7 @@ expr({'try',L,Es0,Cs0,Ecs,[]}, St0) ->
     %% 'try ... of ... catch ... end'
     {Es1,St1} = exprs(Es0, St0),
     {V,St2} = new_var(St1),		%This name should be arbitrary
-    {Cs1,St3} = clauses(Cs0, St2),
+    {Cs1,Ceps,St3} = clauses(Cs0, St2),
     {Fpat,St4} = new_var(St3),
     Lanno = lineno_anno(L, St4),
     Fc = fail_clause([Fpat], Lanno,
@@ -604,7 +610,7 @@ expr({'try',L,Es0,Cs0,Ecs,[]}, St0) ->
     {#itry{anno=#a{anno=lineno_anno(L, St5)},args=Es1,
 	   vars=[V],body=[#icase{anno=#a{anno=Lanno},args=[V],clauses=Cs1,fc=Fc}],
 	   evars=Evs,handler=Hs},
-     [],St5};
+     Ceps,St5};
 expr({'try',L,Es0,[],[],As0}, St0) ->
     %% 'try ... after ... end'
     {Es1,St1} = exprs(Es0, St0),
@@ -673,24 +679,24 @@ expr({match,L,P0,E0}, St0) ->
 	      {var,_,'_'} -> St0#core{wanted=false};
 	      _ -> St0
 	  end,
-    {E2,Eps,St2} = novars(E1, St1),
+    {E2,Eps1,St2} = novars(E1, St1),
     St3 = St2#core{wanted=St0#core.wanted},
-    P2 = try
-	     pattern(P1, St3)
+    {P2,Eps2,St4} = try
+	    pattern(P1, St3)
 	 catch
 	     throw:Thrown ->
-		 Thrown
+		{Thrown,[],St3}
 	 end,
-    {Fpat,St4} = new_var(St3),
-    Lanno = lineno_anno(L, St4),
+    {Fpat,St5} = new_var(St4),
+    Lanno = lineno_anno(L, St5),
     Fc = fail_clause([Fpat], Lanno, c_tuple([#c_literal{val=badmatch},Fpat])),
     case P2 of
 	nomatch ->
-	    St = add_warning(L, nomatch, St4),
+	    St = add_warning(L, nomatch, St5),
 	    {#icase{anno=#a{anno=Lanno},
-		    args=[E2],clauses=[],fc=Fc},Eps,St};
+		    args=[E2],clauses=[],fc=Fc},Eps1++Eps2,St};
 	Other when not is_atom(Other) ->
-	    {#imatch{anno=#a{anno=Lanno},pat=P2,arg=E2,fc=Fc},Eps,St4}
+	    {#imatch{anno=#a{anno=Lanno},pat=P2,arg=E2,fc=Fc},Eps1++Eps2,St5}
     end;
 expr({op,_,'++',{lc,Llc,E,Qs0},More}, St0) ->
     %% Optimise '++' here because of the list comprehension algorithm.
@@ -772,44 +778,77 @@ expr_map(M0,Es0,A,St0) ->
 		    Fc = fail_clause([Fpat], A, #c_literal{val=badarg}),
 		    {#icase{anno=#a{anno=A},args=[M1],clauses=Cs,fc=Fc},Mps,St3};
 		{_,_} ->
-		    {Es1,Eps,St2} = map_pair_list(Es0, St1),
-		    {ann_c_map(A,M1,Es1),Mps++Eps,St2}
+		    {M2,Eps,St2} = map_build_pair_chain(M1,Es0,A,St1),
+		    {M2,Mps++Eps,St2}
 	    end;
 	false -> throw({bad_map,bad_map})
     end.
 
+%% Group continuous literal blocks and single variables, i.e.
+%% M0#{ a := 1, b := V1, K1 := V2, K2 := 42}
+%% becomes equivalent to
+%% M1 = M0#{ a := 1, b := V1 },
+%% M2 = M1#{ K1 := V1 },
+%% M3 = M2#{ K2 := 42 }
+
+map_build_pair_chain(M,Es,A,St) ->
+    %% hack, remove iset if only literal
+    case map_build_pair_chain(M,Es,A,St,[]) of
+	{_,[#iset{arg=#c_literal{}=Val}],St1} -> {Val,[],St1};
+	Normal -> Normal
+    end.
+
+map_build_pair_chain(M0,[],_,St,Mps) ->
+    {M0,Mps,St};
+map_build_pair_chain(M0,Es0,A,St0,Mps) ->
+    % group continuous literal blocks
+    % Anno = #a{anno=[compiler_generated]},
+    % order is important, we need to reverse the literals
+    case map_pair_block(Es0,[],[],St0) of
+	{{CesL,EspL},{[],[]},Es1,St1} ->
+	    {MVar,St2} = new_var(St1),
+	    Pre = [#iset{var=MVar, arg=ann_c_map(A,M0,reverse(CesL))}],
+	    map_build_pair_chain(MVar,Es1,A,St2,Mps++EspL++Pre);
+	{{[],[]},{CesV,EspV},Es1,St1} ->
+	    {MVar,St2} = new_var(St1),
+	    Pre = [#iset{var=MVar, arg=#c_map{arg=M0,es=CesV, anno=A}}],
+	    map_build_pair_chain(MVar,Es1,A,St2,Mps ++ EspV++Pre);
+	{{CesL,EspL},{CesV,EspV},Es1,St1} ->
+	    {MVarL,St2} = new_var(St1),
+	    {MVarV,St3} = new_var(St2),
+	    Pre = [#iset{var=MVarL, arg=ann_c_map(A,M0,reverse(CesL))},
+		   #iset{var=MVarV, arg=#c_map{arg=MVarL,es=CesV,anno=A}}],
+	    map_build_pair_chain(MVarV,Es1,A,St3,Mps++EspL++EspV++Pre)
+    end.
+
+map_pair_block([{Op,L,K0,V0}|Es],Ces,Esp,St0) ->
+    {K,Ep0,St1} = safe(K0, St0),
+    {V,Ep1,St2} = safe(V0, St1),
+    A = lineno_anno(L, St2),
+    Pair0 = map_op_to_c_map_pair(Op),
+    Pair1 = Pair0#c_map_pair{anno=A,key=K,val=V},
+    case cerl:is_literal(K) of
+	true ->
+	    map_pair_block(Es,[Pair1|Ces],Ep0 ++ Ep1 ++ Esp,St2);
+	false ->
+	    {{Ces,Esp},{[Pair1],Ep0++Ep1},Es,St2}
+    end;
+map_pair_block([],Ces,Esp,St) ->
+    {{Ces,Esp},{[],[]},[],St}.
+
+map_op_to_c_map_pair(map_field_assoc) -> #c_map_pair{op=#c_literal{val=assoc}};
+map_op_to_c_map_pair(map_field_exact) -> #c_map_pair{op=#c_literal{val=exact}}.
+
 is_valid_map_src(#c_literal{val = M}) when is_map(M) -> true;
-is_valid_map_src(#c_map{})  -> true;
 is_valid_map_src(#c_var{})  -> true;
 is_valid_map_src(_)         -> false.
 
-map_pair_list(Es, St) ->
-    foldr(fun
-	    ({map_field_assoc,L,K0,V0}, {Ces,Esp,St0}) ->
-		{K,Ep0,St1} = safe(K0, St0),
-		ok = ensure_valid_map_key(K),
-		{V,Ep1,St2} = safe(V0, St1),
-		A = lineno_anno(L, St2),
-		Pair = #c_map_pair{op=#c_literal{val=assoc},anno=A,key=K,val=V},
-		{[Pair|Ces],Ep0 ++ Ep1 ++ Esp,St2};
-	    ({map_field_exact,L,K0,V0}, {Ces,Esp,St0}) ->
-		{K,Ep0,St1} = safe(K0, St0),
-		ok = ensure_valid_map_key(K),
-		{V,Ep1,St2} = safe(V0, St1),
-		A = lineno_anno(L, St2),
-		Pair = #c_map_pair{op=#c_literal{val=exact},anno=A,key=K,val=V},
-		{[Pair|Ces],Ep0 ++ Ep1 ++ Esp,St2}
-	end, {[],[],St}, Es).
-
-ensure_valid_map_key(#c_literal{}) -> ok;
-ensure_valid_map_key(_) -> throw({bad_map,bad_map_key}).
-
 %% try_exception([ExcpClause], St) -> {[ExcpVar],Handler,St}.
 
 try_exception(Ecs0, St0) ->
     %% Note that Tag is not needed for rethrow - it is already in Info.
     {Evs,St1} = new_vars(3, St0), % Tag, Value, Info
-    {Ecs1,St2} = clauses(Ecs0, St1),
+    {Ecs1,Ceps,St2} = clauses(Ecs0, St1),
     [_,Value,Info] = Evs,
     Ec = #iclause{anno=#a{anno=[compiler_generated]},
 		  pats=[c_tuple(Evs)],guard=[#c_literal{val=true}],
@@ -817,15 +856,15 @@ try_exception(Ecs0, St0) ->
 				 name=#c_literal{val=raise},
 				 args=[Info,Value]}]},
     Hs = [#icase{anno=#a{},args=[c_tuple(Evs)],clauses=Ecs1,fc=Ec}],
-    {Evs,Hs,St2}.
+    {Evs,Ceps++Hs,St2}.
 
 try_after(As, St0) ->
     %% See above.
-    {Evs,St1} = new_vars(3, St0),		% Tag, Value, Info
+    {Evs,St1} = new_vars(3, St0),	 % Tag, Value, Info
     [_,Value,Info] = Evs,
-    B = As ++ [#iprimop{anno=#a{},       %Must have an #a{}
-			 name=#c_literal{val=raise},
-			 args=[Info,Value]}],
+    B = As ++ [#iprimop{anno=#a{},       % Must have an #a{}
+			name=#c_literal{val=raise},
+			args=[Info,Value]}],
     Ec = #iclause{anno=#a{anno=[compiler_generated]},
 		  pats=[c_tuple(Evs)],guard=[#c_literal{val=true}],
 		  body=B},
@@ -959,7 +998,7 @@ bitstr({bin_element,_,E0,Size0,[Type,{unit,Unit}|Flags]}, St0) ->
 
 fun_tq({_,_,Name}=Id, Cs0, L, St0, NameInfo) ->
     Arity = clause_arity(hd(Cs0)),
-    {Cs1,St1} = clauses(Cs0, St0),
+    {Cs1,Ceps,St1} = clauses(Cs0, St0),
     {Args,St2} = new_vars(Arity, St1),
     {Ps,St3} = new_vars(Arity, St2),		%Need new variables here
     Anno = lineno_anno(L, St3),
@@ -967,7 +1006,7 @@ fun_tq({_,_,Name}=Id, Cs0, L, St0, NameInfo) ->
     Fun = #ifun{anno=#a{anno=Anno},
 		id=[{id,Id}],				%We KNOW!
 		vars=Args,clauses=Cs1,fc=Fc,name=NameInfo},
-    {Fun,[],St3}.
+    {Fun,Ceps,St3}.
 
 %% lc_tq(Line, Exp, [Qualifier], Mc, State) -> {LetRec,[PreExp],State}.
 %%  This TQ from Simon PJ pp 127-138.  
@@ -1181,7 +1220,7 @@ is_generator(_) -> false.
 generator(Line, {generate,Lg,P0,E}, Gs, St0) ->
     LA = lineno_anno(Line, St0),
     GA = lineno_anno(Lg, St0),
-    {Head,St1} = list_gen_pattern(P0, Line, St0),
+    {Head,Ceps,St1} = list_gen_pattern(P0, Line, St0),
     {[Tail,Skip],St2} = new_vars(2, St1),
     {Cg,St3} = lc_guard_tests(Gs, St2),
     {AccPat,SkipPat} = case Head of
@@ -1202,24 +1241,25 @@ generator(Line, {generate,Lg,P0,E}, Gs, St0) ->
                        end,
     {Ce,Pre,St4} = safe(E, St3),
     Gen = #igen{anno=#a{anno=GA},acc_pat=AccPat,acc_guard=Cg,skip_pat=SkipPat,
-                tail=Tail,tail_pat=#c_literal{anno=LA,val=[]},arg={Pre,Ce}},
+                tail=Tail,tail_pat=#c_literal{anno=LA,val=[]},arg={Ceps++Pre,Ce}},
     {Gen,St4};
 generator(Line, {b_generate,Lg,P,E}, Gs, St0) ->
     LA = lineno_anno(Line, St0),
     GA = lineno_anno(Lg, St0),
-    Cp = #c_binary{segments=Segs} = pattern(P, St0),
+    {Cp = #c_binary{segments=Segs},[],St1} = pattern(P, St0),
+    
     %% The function append_tail_segment/2 keeps variable patterns as-is, making
     %% it possible to have the same skip clause removal as with list generators.
-    {AccSegs,Tail,TailSeg,St1} = append_tail_segment(Segs, St0),
+    {AccSegs,Tail,TailSeg,St2} = append_tail_segment(Segs, St1),
     AccPat = Cp#c_binary{segments=AccSegs},
-    {Cg,St2} = lc_guard_tests(Gs, St1),
-    {SkipSegs,St3} = emasculate_segments(AccSegs, St2),
+    {Cg,St3} = lc_guard_tests(Gs, St2),
+    {SkipSegs,St4} = emasculate_segments(AccSegs, St3),
     SkipPat = Cp#c_binary{segments=SkipSegs},
-    {Ce,Pre,St4} = safe(E, St3),
+    {Ce,Pre,St5} = safe(E, St4),
     Gen = #igen{anno=#a{anno=GA},acc_pat=AccPat,acc_guard=Cg,skip_pat=SkipPat,
                 tail=Tail,tail_pat=#c_binary{anno=LA,segments=[TailSeg]},
                 arg={Pre,Ce}},
-    {Gen,St4}.
+    {Gen,St5}.
 
 append_tail_segment(Segs, St0) ->
     {Var,St} = new_var(St0),
@@ -1248,9 +1288,9 @@ lc_guard_tests(Gs0, St0) ->
 
 list_gen_pattern(P0, Line, St) ->
     try
-	{pattern(P0, St),St}
+	pattern(P0,St)
     catch 
-	nomatch -> {nomatch,add_warning(Line, nomatch, St)}
+	nomatch -> {nomatch,[],add_warning(Line, nomatch, St)}
     end.
 
 %%%
@@ -1473,6 +1513,18 @@ force_novars(#ibinary{}=Bin, St) -> {Bin,[],St};
 force_novars(Ce, St) ->
     force_safe(Ce, St).
 
+
+%% safe_pattern_expr(Expr, State) -> {Cexpr,[PreExpr],State}.
+%%   only literals and variables are safe expressions in patterns
+safe_pattern_expr(E,St0) ->
+    case safe(E,St0) of
+	{#c_var{},_,_}=Safe -> Safe;
+	{#c_literal{},_,_}=Safe -> Safe;
+	{Ce,Eps,St1} ->
+	    {V,St2} = new_var(St1),
+	    {V,Eps++[#iset{var=V,arg=Ce}],St2}
+    end.
+
 %% safe(Expr, State) -> {Safe,[PreExpr],State}.
 %%  Generate an internal safe expression.  These are simples without
 %%  binaries which can fail.  At this level we do not need to do a
@@ -1547,84 +1599,109 @@ fold_match({match,L,P0,E0}, P) ->
     {{match,L,P0,P1},E1};
 fold_match(E, P) -> {P,E}.
 
-%% pattern(Pattern, State) -> CorePat.
+%% pattern(Pattern, State) -> {CorePat,[PreExp],State}.
 %% Transform a pattern by removing line numbers.  We also normalise
 %% aliases in patterns to standard form, {alias,Pat,[Var]}.
-
-pattern({var,L,V}, St) -> #c_var{anno=lineno_anno(L, St),name=V};
-pattern({char,L,C}, St) -> #c_literal{anno=lineno_anno(L, St),val=C};
-pattern({integer,L,I}, St) -> #c_literal{anno=lineno_anno(L, St),val=I};
-pattern({float,L,F}, St) -> #c_literal{anno=lineno_anno(L, St),val=F};
-pattern({atom,L,A}, St) -> #c_literal{anno=lineno_anno(L, St),val=A};
-pattern({string,L,S}, St) -> #c_literal{anno=lineno_anno(L, St),val=S};
-pattern({nil,L}, St) -> #c_literal{anno=lineno_anno(L, St),val=[]};
+%%
+%% In patterns we may have expressions
+%% 1) Binaries -> #c_bitstr{size=Expr}
+%% 2) Maps -> #c_map_pair{key=Expr}
+%%
+%% Both of these may generate pre-expressions since only bound variables
+%% or literals are allowed for these in core patterns.
+%%
+%% Therefor, we need to drag both the state and the collection of pre-expression
+%% around in the whole pattern transformation tree.
+
+pattern({var,L,V}, St) -> {#c_var{anno=lineno_anno(L, St),name=V},[],St};
+pattern({char,L,C}, St) -> {#c_literal{anno=lineno_anno(L, St),val=C},[],St};
+pattern({integer,L,I}, St) -> {#c_literal{anno=lineno_anno(L, St),val=I},[],St};
+pattern({float,L,F}, St) -> {#c_literal{anno=lineno_anno(L, St),val=F},[],St};
+pattern({atom,L,A}, St) -> {#c_literal{anno=lineno_anno(L, St),val=A},[],St};
+pattern({string,L,S}, St) -> {#c_literal{anno=lineno_anno(L, St),val=S},[],St};
+pattern({nil,L}, St) -> {#c_literal{anno=lineno_anno(L, St),val=[]},[],St};
 pattern({cons,L,H,T}, St) ->
-    annotate_cons(lineno_anno(L, St), pattern(H, St), pattern(T, St), St);
+    {Ph,Eps1,St1} = pattern(H, St),
+    {Pt,Eps2,St2} = pattern(T, St1),
+    {annotate_cons(lineno_anno(L, St), Ph, Pt, St2),Eps1++Eps2,St2};
 pattern({tuple,L,Ps}, St) ->
-    annotate_tuple(record_anno(L, St), pattern_list(Ps, St), St);
-pattern({map,L,Ps}, St) ->
-    #c_map{anno=lineno_anno(L, St), es=pattern_map_pairs(Ps, St)};
+    {Ps1,Eps,St1} = pattern_list(Ps,St),
+    {annotate_tuple(record_anno(L, St), Ps1, St),Eps,St1};
+pattern({map,L,Pairs}, St0) ->
+    {Ps,Eps,St1} = pattern_map_pairs(Pairs, St0),
+    {#c_map{anno=lineno_anno(L, St1), es=Ps},Eps,St1};
 pattern({bin,L,Ps}, St) ->
     %% We don't create a #ibinary record here, since there is
     %% no need to hold any used/new annotations in a pattern.
-    #c_binary{anno=lineno_anno(L, St),segments=pat_bin(Ps, St)};
+    {#c_binary{anno=lineno_anno(L, St),segments=pat_bin(Ps, St)},[],St};
 pattern({match,_,P1,P2}, St) ->
-    pat_alias(pattern(P1, St), pattern(P2, St)).
+    {Cp1,Eps1,St1} = pattern(P1,St),
+    {Cp2,Eps2,St2} = pattern(P2,St1),
+    {pat_alias(Cp1,Cp2),Eps1++Eps2,St2}.
 
 %% pattern_map_pairs([MapFieldExact],State) -> [#c_map_pairs{}]
 pattern_map_pairs(Ps, St) ->
-    %% check literal key uniqueness (dict is needed)
-    %% pattern all pairs
-    {CMapPairs, Kdb} = lists:mapfoldl(fun
-	    (P,Kdbi) ->
-		#c_map_pair{key=Ck,val=Cv} = CMapPair = pattern_map_pair(P,St),
-		K = core_lib:literal_value(Ck),
-		case dict:find(K,Kdbi) of
-		    {ok, Vs} ->
-			{CMapPair, dict:store(K,[Cv|Vs],Kdbi)};
-		    _ ->
-			{CMapPair, dict:store(K,[Cv],Kdbi)}
+    %% check literal key uniqueness
+    %%   - guaranteed via aliasing map pairs
+    %% pattern all pairs in two steps
+    %% 1) Construct Core Pattern
+    %% 2) Alias Keys in Core Pattern
+    {CMapPairs, {Eps,St1}} = lists:mapfoldl(fun
+	    (P,{EpsM,Sti0}) ->
+		{CMapPair,EpsP,Sti1} = pattern_map_pair(P,Sti0),
+		{CMapPair, {EpsM++EpsP,Sti1}}
+	end, {[],St}, Ps),
+    {pat_alias_map_pairs(CMapPairs,[]),Eps,St1}.
+
+%% remove cluddering annotations
+pattern_map_clean_key(#c_literal{val=V}) -> {literal,V};
+pattern_map_clean_key(#c_var{name=V}) -> {var,V}.
+
+pat_alias_map_pairs(Ps1,Ps2) ->
+    Ps = Ps1 ++ Ps2,
+    F = fun(#c_map_pair{key=Ck,val=Cv},Dbi) ->
+		K = pattern_map_clean_key(Ck),
+		case dict:find(K,Dbi) of
+		    {ok,Cvs} -> dict:store(K,[Cv|Cvs],Dbi);
+		    _        -> dict:store(K,[Cv],Dbi)
 		end
-	end, dict:new(), Ps),
-    pattern_alias_map_pairs(CMapPairs,Kdb,dict:new(),St).
-
-pattern_alias_map_pairs([],_,_,_) -> [];
-pattern_alias_map_pairs([#c_map_pair{key=Ck}=Pair|Pairs],Kdb,Kset,St) ->
-    %% alias same keys if needed
-    K = core_lib:literal_value(Ck),
-    case dict:find(K,Kset) of
-	{ok,processed} ->
-	    pattern_alias_map_pairs(Pairs,Kdb,Kset,St);
-	_ ->
+	end,
+    Kdb = lists:foldl(F,dict:new(),Ps),
+    pat_alias_map_pairs(Ps,Kdb,sets:new()).
+
+pat_alias_map_pairs([],_,_) -> [];
+pat_alias_map_pairs([#c_map_pair{key=Ck}=Pair|Pairs],Kdb,Set) ->
+    K = pattern_map_clean_key(Ck),
+    case sets:is_element(K,Set) of
+	true ->
+	    pat_alias_map_pairs(Pairs,Kdb,Set);
+	false ->
 	    Cvs = dict:fetch(K,Kdb),
-	    Cv = pattern_alias_map_pair_patterns(Cvs),
-	    Kset1 = dict:store(K, processed, Kset),
-	    [Pair#c_map_pair{val=Cv}|pattern_alias_map_pairs(Pairs,Kdb,Kset1,St)]
+	    Cv = pat_alias_map_pair_values(Cvs),
+	    Set1 = sets:add_element(K,Set),
+	    [Pair#c_map_pair{val=Cv}|pat_alias_map_pairs(Pairs,Kdb,Set1)]
     end.
 
-pattern_alias_map_pair_patterns([Cv]) -> Cv;
-pattern_alias_map_pair_patterns([Cv1,Cv2|Cvs]) ->
-    pattern_alias_map_pair_patterns([pat_alias(Cv1,Cv2)|Cvs]).
-
-pattern_map_pair({map_field_exact,L,K,V}, St) ->
-    case expr(K,St) of
-	{#c_literal{}=Key,_,_} ->
-	    #c_map_pair{anno=lineno_anno(L, St),
-			op=#c_literal{val=exact},
-			key=Key,
-			val=pattern(V, St)};
-	_ ->
-	    %% this will throw a cryptic error message
-	    %% but it is better than nothing
-	    throw(nomatch)
-    end.
+pat_alias_map_pair_values([Cv]) -> Cv;
+pat_alias_map_pair_values([Cv1,Cv2|Cvs]) ->
+    pat_alias_map_pair_values([pat_alias(Cv1,Cv2)|Cvs]).
+
+pattern_map_pair({map_field_exact,L,K,V}, St0) ->
+    {Ck,EpsK,St1} = safe_pattern_expr(K,St0),
+    {Cv,EpsV,St2} = pattern(V, St1),
+    {#c_map_pair{anno=lineno_anno(L,St2),
+		 op=#c_literal{val=exact},
+		 key=Ck,
+		 val=Cv},EpsK++EpsV,St2}.
 
 %% pat_bin([BinElement], State) -> [BinSeg].
 
 pat_bin(Ps, St) -> [pat_segment(P, St) || P <- Ps].
 
-pat_segment({bin_element,_,Term,Size,[Type,{unit,Unit}|Flags]}, St) ->
-    #c_bitstr{val=pattern(Term, St),size=pattern(Size, St),
+pat_segment({bin_element,_,Val,Size,[Type,{unit,Unit}|Flags]}, St) ->
+    {Pval,[],St1} = pattern(Val,St),
+    {Psize,[],_St2} = pattern(Size,St1),
+    #c_bitstr{val=Pval,size=Psize,
 	      unit=#c_literal{val=Unit},
 	      type=#c_literal{val=Type},
 	      flags=#c_literal{val=Flags}}.
@@ -1634,6 +1711,8 @@ pat_segment({bin_element,_,Term,Size,[Type,{unit,Unit}|Flags]}, St) ->
 
 pat_alias(#c_var{name=V1}, P2) -> #c_alias{var=#c_var{name=V1},pat=P2};
 pat_alias(P1, #c_var{name=V2}) -> #c_alias{var=#c_var{name=V2},pat=P1};
+
+%% alias cons
 pat_alias(#c_cons{}=Cons, #c_literal{anno=A,val=[H|T]}=S) ->
     pat_alias(Cons, ann_c_cons_skel(A, #c_literal{anno=A,val=H},
 				    S#c_literal{val=T}));
@@ -1642,6 +1721,8 @@ pat_alias(#c_literal{anno=A,val=[H|T]}=S, #c_cons{}=Cons) ->
 			      S#c_literal{val=T}), Cons);
 pat_alias(#c_cons{anno=Anno,hd=H1,tl=T1}, #c_cons{hd=H2,tl=T2}) ->
     ann_c_cons(Anno, pat_alias(H1, H2), pat_alias(T1, T2));
+
+%% alias tuples
 pat_alias(#c_tuple{anno=Anno,es=Es1}, #c_literal{val=T}) when is_tuple(T) ->
     Es2 = [#c_literal{val=E} || E <- tuple_to_list(T)],
     ann_c_tuple(Anno, pat_alias_list(Es1, Es2));
@@ -1650,6 +1731,12 @@ pat_alias(#c_literal{anno=Anno,val=T}, #c_tuple{es=Es2}) when is_tuple(T) ->
     ann_c_tuple(Anno, pat_alias_list(Es1, Es2));
 pat_alias(#c_tuple{anno=Anno,es=Es1}, #c_tuple{es=Es2}) ->
     ann_c_tuple(Anno, pat_alias_list(Es1, Es2));
+
+%% alias maps
+%% There are no literals in maps patterns (patterns are always abstract)
+pat_alias(#c_map{es=Es1}=M,#c_map{es=Es2}) ->
+    M#c_map{es=pat_alias_map_pairs(Es1,Es2)};
+
 pat_alias(#c_alias{var=V1,pat=P1},
 	  #c_alias{var=V2,pat=P2}) ->
     if V1 =:= V2 -> #c_alias{var=V1,pat=pat_alias(P1, P2)};
@@ -1672,9 +1759,15 @@ pat_alias_list([A1|A1s], [A2|A2s]) ->
 pat_alias_list([], []) -> [];
 pat_alias_list(_, _) -> throw(nomatch).
 
-%% pattern_list([P], State) -> [P].
+%% pattern_list([P], State) -> {[P],Exprs,St}
+
+pattern_list([P0|Ps0], St0) ->
+    {P1,Eps,St1} = pattern(P0, St0),
+    {Ps1,Epsl,St2} = pattern_list(Ps0, St1),
+    {[P1|Ps1], Eps ++ Epsl, St2};
+pattern_list([], St) ->
+    {[],[],St}.
 
-pattern_list(Ps, St) -> [pattern(P, St) || P <- Ps].
 
 %% make_vars([Name]) -> [{Var,Name}].
 
@@ -1974,9 +2067,14 @@ upattern(#c_tuple{es=Es0}=Tuple, Ks, St0) ->
 upattern(#c_map{es=Es0}=Map, Ks, St0) ->
     {Es1,Esg,Esv,Eus,St1} = upattern_list(Es0, Ks, St0),
     {Map#c_map{es=Es1},Esg,Esv,Eus,St1};
-upattern(#c_map_pair{op=#c_literal{val=exact},val=V0}=MapPair, Ks, St0) ->
-    {V,Vg,Vv,Vu,St1} = upattern(V0, Ks, St0),
-    {MapPair#c_map_pair{val=V},Vg,Vv,Vu,St1};
+upattern(#c_map_pair{op=#c_literal{val=exact},key=K0,val=V0}=Pair,Ks,St0) ->
+    {V,Vg,Vn,Vu,St1} = upattern(V0, Ks, St0),
+    % A variable key must be considered used here
+    Ku = case K0 of
+	#c_var{name=Name} -> [Name];
+	_ -> []
+    end,
+    {Pair#c_map_pair{val=V},Vg,Vn,union(Ku,Vu),St1};
 upattern(#c_binary{segments=Es0}=Bin, Ks, St0) ->
     {Es1,Esg,Esv,Eus,St1} = upat_bin(Es0, Ks, St0),
     {Bin#c_binary{segments=Es1},Esg,Esv,Eus,St1};
@@ -2347,8 +2445,6 @@ format_error(nomatch) ->
     "pattern cannot possibly match";
 format_error(bad_binary) ->
     "binary construction will fail because of a type mismatch";
-format_error(bad_map_key) ->
-    "map construction will fail because of none literal key (large binaries are not literals)";
 format_error(bad_map) ->
     "map construction will fail because of a type mismatch".
 
diff --git a/lib/compiler/src/v3_kernel.erl b/lib/compiler/src/v3_kernel.erl
index 40d2f72b4c..6504351c02 100644
--- a/lib/compiler/src/v3_kernel.erl
+++ b/lib/compiler/src/v3_kernel.erl
@@ -527,9 +527,9 @@ map_split_pairs(A, Var, Ces, Sub, St0) ->
     Pairs0 = [{Op,K,V} || #c_map_pair{op=#c_literal{val=Op},key=K,val=V} <- Ces],
     {Pairs,Esp,St1} = foldr(fun
 	    ({Op,K0,V0}, {Ops,Espi,Sti0}) when Op =:= assoc; Op =:= exact ->
-		{K,[],Sti1} = expr(K0, Sub, Sti0),
-		{V,Ep,Sti2} = atomic(V0, Sub, Sti1),
-		{[{Op,K,V}|Ops],Ep ++ Espi,Sti2}
+		{K,Eps1,Sti1} = atomic(K0, Sub, Sti0),
+		{V,Eps2,Sti2} = atomic(V0, Sub, Sti1),
+		{[{Op,K,V}|Ops],Eps1 ++ Eps2 ++ Espi,Sti2}
 	end, {[],[],St0}, Pairs0),
 
     case map_group_pairs(Pairs) of
@@ -577,11 +577,12 @@ map_key_is_used(K,Used) ->
     dict:find(map_key_clean(K),Used).
 
 %% Be explicit instead of using set_kanno(K,[])
-map_key_clean(#k_literal{val=V}) -> {k_literal,V};
-map_key_clean(#k_int{val=V})     -> {k_int,V};
-map_key_clean(#k_float{val=V})   -> {k_float,V};
-map_key_clean(#k_atom{val=V})    -> {k_atom,V};
-map_key_clean(#k_nil{})          -> k_nil.
+map_key_clean(#k_var{name=V})    -> {var,V};
+map_key_clean(#k_literal{val=V}) -> {lit,V};
+map_key_clean(#k_int{val=V})     -> {lit,V};
+map_key_clean(#k_float{val=V})   -> {lit,V};
+map_key_clean(#k_atom{val=V})    -> {lit,V};
+map_key_clean(#k_nil{})          -> {lit,[]}.
 
 
 %% call_type(Module, Function, Arity) -> call | bif | apply | error.
@@ -757,23 +758,22 @@ flatten_alias(#c_alias{var=V,pat=P}) ->
 flatten_alias(Pat) -> {[],Pat}.
 
 pattern_map_pairs(Ces0, Isub, Osub0, St0) ->
-    %% It is assumed that all core keys are literals
-    %% It is later assumed that these keys are term sorted
-    %% so we need to sort them here
-    Ces1 = lists:sort(fun
-	    (#c_map_pair{key=CkA},#c_map_pair{key=CkB}) ->
-		A = core_lib:literal_value(CkA),
-		B = core_lib:literal_value(CkB),
-		erts_internal:cmp_term(A,B) < 0
-	end, Ces0),
     %% pattern the pair keys and values as normal
     {Kes,{Osub1,St1}} = lists:mapfoldl(fun
 	    (#c_map_pair{anno=A,key=Ck,val=Cv},{Osubi0,Sti0}) ->
-		{Kk,Osubi1,Sti1} = pattern(Ck, Isub, Osubi0, Sti0),
-		{Kv,Osubi2,Sti2} = pattern(Cv, Isub, Osubi1, Sti1),
+		{Kk,[],Sti1} = expr(Ck, Isub, Sti0),
+		{Kv,Osubi2,Sti2} = pattern(Cv, Isub, Osubi0, Sti1),
 		{#k_map_pair{anno=A,key=Kk,val=Kv},{Osubi2,Sti2}}
-	end, {Osub0, St0}, Ces1),
-    {Kes,Osub1,St1}.
+	end, {Osub0, St0}, Ces0),
+    %% It is later assumed that these keys are term sorted
+    %% so we need to sort them here
+    Kes1 = lists:sort(fun
+	    (#k_map_pair{key=KkA},#k_map_pair{key=KkB}) ->
+		A = map_key_clean(KkA),
+		B = map_key_clean(KkB),
+		erts_internal:cmp_term(A,B) < 0
+	end, Kes),
+    {Kes1,Osub1,St1}.
 
 pattern_bin(Es, Isub, Osub0, St0) ->
     {Kbin,{_,Osub},St} = pattern_bin_1(Es, Isub, Osub0, St0),
@@ -1550,13 +1550,11 @@ arg_val(Arg, C) ->
 		    {set_kanno(S, []),U,T,Fs}
 	    end;
 	#k_map{op=exact,es=Es} ->
-	    Keys = [begin
-			#k_map_pair{key=#k_literal{val=Key}} = Pair,
-			Key
-		    end || Pair <- Es],
-	    %% multiple keys may have the same name
-	    %% do not use ordsets
-	    lists:sort(fun(A,B) -> erts_internal:cmp_term(A,B) < 0 end, Keys)
+	    lists:sort(fun(A,B) ->
+			%% on the form K :: {'lit' | 'var', term()}
+			%% lit < var as intended
+			erts_internal:cmp_term(A,B) < 0
+		end, [map_key_clean(Key) || #k_map_pair{key=Key} <- Es])
     end.
 
 %% ubody_used_vars(Expr, State) -> [UsedVar]
@@ -1943,6 +1941,7 @@ lit_list_vars(Ps) ->
 %% pat_vars(Pattern) -> {[UsedVarName],[NewVarName]}.
 %%  Return variables in a pattern.  All variables are new variables
 %%  except those in the size field of binary segments.
+%%  and map_pair keys
 
 pat_vars(#k_var{name=N}) -> {[],[N]};
 %%pat_vars(#k_char{}) -> {[],[]};
@@ -1967,8 +1966,10 @@ pat_vars(#k_tuple{es=Es}) ->
     pat_list_vars(Es);
 pat_vars(#k_map{es=Es}) ->
     pat_list_vars(Es);
-pat_vars(#k_map_pair{val=V}) ->
-    pat_vars(V).
+pat_vars(#k_map_pair{key=K,val=V}) ->
+    {U1,New} = pat_vars(V),
+    {[], U2} = pat_vars(K),
+    {union(U1,U2),New}.
 
 pat_list_vars(Ps) ->
     foldl(fun (P, {Used0,New0}) ->
diff --git a/lib/compiler/src/v3_kernel.hrl b/lib/compiler/src/v3_kernel.hrl
index ab66445f73..b008285d9f 100644
--- a/lib/compiler/src/v3_kernel.hrl
+++ b/lib/compiler/src/v3_kernel.hrl
@@ -38,7 +38,7 @@
 -record(k_nil, {anno=[]}).
 
 -record(k_tuple, {anno=[],es}).
--record(k_map, {anno=[],var,op,es}).
+-record(k_map, {anno=[],var=#k_literal{val=#{}},op,es}).
 -record(k_map_pair, {anno=[],key,val}).
 -record(k_cons, {anno=[],hd,tl}).
 -record(k_binary, {anno=[],segs}).