Merge branch 'bjorn/compiler/optimizations/OTP-11584'

* bjorn/compiler/optimizations/OTP-11584:
  Generalize optimizations of case statements
  Ignore warnings when running sys_core_fold after inlining

4 files changed, 299 insertions, 223 deletions

diff --git a/lib/compiler/src/compile.erl b/lib/compiler/src/compile.erl
index 38a733751a..3db7ffc4d2 100644
--- a/lib/compiler/src/compile.erl
+++ b/lib/compiler/src/compile.erl
@@ -612,7 +612,7 @@ core_passes() ->
 	?pass(core_fold_module),
 	{core_inline_module,fun test_core_inliner/1,fun core_inline_module/1},
 	{iff,dinline,{listing,"inline"}},
-	{core_fold_after_inline,fun test_core_inliner/1,fun core_fold_module/1},
+	{core_fold_after_inlining,fun test_core_inliner/1,fun core_fold_module_after_inlining/1},
 	?pass(core_transforms)]},
        {iff,dcopt,{listing,"copt"}},
        {iff,'to_core',{done,"core"}}]}
@@ -1134,6 +1134,12 @@ core_fold_module(#compile{code=Code0,options=Opts,warnings=Warns}=St) ->
     {ok,Code,Ws} = sys_core_fold:module(Code0, Opts),
     {ok,St#compile{code=Code,warnings=Warns ++ Ws}}.
 
+core_fold_module_after_inlining(#compile{code=Code0,options=Opts}=St) ->
+    %% Inlining may produce code that generates spurious warnings.
+    %% Ignore all warnings.
+    {ok,Code,_Ws} = sys_core_fold:module(Code0, Opts),
+    {ok,St#compile{code=Code}}.
+
 test_old_inliner(#compile{options=Opts}) ->
     %% The point of this test is to avoid loading the old inliner
     %% if we know that it will not be used.
diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl
index e2002c8e48..a388960312 100644
--- a/lib/compiler/src/sys_core_fold.erl
+++ b/lib/compiler/src/sys_core_fold.erl
@@ -70,7 +70,7 @@
 -export([module/2,format_error/1]).
 
 -import(lists, [map/2,foldl/3,foldr/3,mapfoldl/3,all/2,any/2,
-		reverse/1,reverse/2,member/2,nth/2,flatten/1]).
+		reverse/1,reverse/2,member/2,nth/2,flatten/1,unzip/1]).
 
 -import(cerl, [ann_c_cons/3,ann_c_tuple/2]).
 
@@ -302,18 +302,49 @@ expr(#c_letrec{defs=Fs0,body=B0}=Letrec, Ctxt, Sub) ->
     B1 = body(B0, value, Sub),
     Letrec#c_letrec{defs=Fs1,body=B1};
 expr(#c_case{}=Case0, Ctxt, Sub) ->
+    %% Ideally, the compiler should only emit warnings when there is
+    %% a real mistake in the code being compiled. We use the follow
+    %% heuristics in an attempt to approach that ideal:
+    %%
+    %% * If the guard for a clause always fails, we will emit a
+    %%   warning.
+    %%
+    %% * If a case expression is a literal, we will emit no warnings
+    %%   for clauses that will not match or for clauses that are
+    %%   shadowed after a clause that will always match. That means
+    %%   that code such as:
+    %%
+    %%      case ?DEBUG of
+    %%         false -> ok;
+    %%         true -> ...
+    %%      end
+    %%
+    %%   (where ?DEBUG expands to either 'true' or 'false') will not
+    %%   produce any warnings.
+    %%
+    %% * If the case expression is not literal, warnings will be
+    %%   emitted for every clause that don't match and for all
+    %%   clauses following a clause that will always match.
+    %%
+    %% * If no clause will ever match, there will be a warning
+    %%   (in addition to any warnings that may have been emitted
+    %%   according to the rules above).
+    %%
     case opt_bool_case(Case0) of
 	#c_case{arg=Arg0,clauses=Cs0}=Case1 ->
 	    Arg1 = body(Arg0, value, Sub),
-	    {Arg2,Cs1} = case_opt(Arg1, Cs0),
-	    Cs2 = clauses(Arg2, Cs1, Case1, Ctxt, Sub),
-	    Case = eval_case(Case1#c_case{arg=Arg2,clauses=Cs2}, Sub),
-	    bsm_an(Case);
+	    LitExpr = cerl:is_literal(Arg1),
+	    {Arg2,Cs1} = case_opt(Arg1, Cs0, Sub),
+	    Cs2 = clauses(Arg2, Cs1, Ctxt, Sub, LitExpr),
+	    Case = Case1#c_case{arg=Arg2,clauses=Cs2},
+	    warn_no_clause_match(Case1, Case),
+	    Expr = eval_case(Case, Sub),
+	    bsm_an(Expr);
 	Other ->
 	    expr(Other, Ctxt, Sub)
     end;
 expr(#c_receive{clauses=Cs0,timeout=T0,action=A0}=Recv, Ctxt, Sub) ->
-    Cs1 = clauses(#c_var{name='_'}, Cs0, Recv, Ctxt, Sub), %This is all we know
+    Cs1 = clauses(#c_var{name='_'}, Cs0, Ctxt, Sub, false),
     T1 = expr(T0, value, Sub),
     A1 = body(A0, Ctxt, Sub),
     Recv#c_receive{clauses=Cs1,timeout=T1,action=A1};
@@ -1582,39 +1613,39 @@ v_is_value(Var, [{_,#c_var{name=Var}}|_]) -> true;
 v_is_value(Var, [_|T]) -> v_is_value(Var, T);
 v_is_value(_, []) -> false.
 
-%% clauses(E, [Clause], TopLevel, Context, Sub) -> [Clause].
-%%  Trim the clauses by removing all clauses AFTER the first one which
-%%  is guaranteed to match.  Also remove all trivially false clauses.
+%% warn_no_clause_match(CaseOrig, CaseOpt) -> ok
+%%  Generate a warning if none of the user-specified clauses
+%%  will match.
 
-clauses(E, Cs0, TopLevel, Ctxt, Sub) ->
-    Cs = clauses_1(E, Cs0, Ctxt, Sub),
-
-    %% Here we want to warn if no clauses whatsoever will ever
-    %% match, because that is probably a mistake.
-    case all(fun is_compiler_generated/1, Cs) andalso
-	any(fun(C) -> not is_compiler_generated(C) end, Cs0) of
+warn_no_clause_match(CaseOrig, CaseOpt) ->
+    OrigCs = cerl:case_clauses(CaseOrig),
+    OptCs = cerl:case_clauses(CaseOpt),
+    case any(fun(C) -> not is_compiler_generated(C) end, OrigCs) andalso
+	all(fun is_compiler_generated/1, OptCs) of
 	true ->
 	    %% The original list of clauses did contain at least one
 	    %% user-specified clause, but none of them will match.
 	    %% That is probably a mistake.
-	    add_warning(TopLevel, no_clause_match);
+	    add_warning(CaseOrig, no_clause_match);
 	false ->
 	    %% Either there were user-specified clauses left in
 	    %% the transformed clauses, or else none of the original
 	    %% clauses were user-specified to begin with (as in 'andalso').
 	    ok
-    end,
+    end.
 
-    Cs.
+%% clauses(E, [Clause], TopLevel, Context, Sub) -> [Clause].
+%%  Trim the clauses by removing all clauses AFTER the first one which
+%%  is guaranteed to match.  Also remove all trivially false clauses.
 
-clauses_1(E, [C0|Cs], Ctxt, Sub) ->
+clauses(E, [C0|Cs], Ctxt, Sub, LitExpr) ->
     #c_clause{pats=Ps,guard=G} = C1 = clause(C0, E, Ctxt, Sub),
     %%ok = io:fwrite("~w: ~p~n", [?LINE,{E,Ps}]),
     case {will_match(E, Ps),will_succeed(G)} of
 	{yes,yes} ->
-	    Line = get_line(core_lib:get_anno(C1)),
-	    case core_lib:is_literal(E) of
+	    case LitExpr of
 		false ->
+		    Line = get_line(core_lib:get_anno(C1)),
 		    shadow_warning(Cs, Line);
 		true ->
 		    %% If the case expression is a literal,
@@ -1623,15 +1654,13 @@ clauses_1(E, [C0|Cs], Ctxt, Sub) ->
 		    ok
 	    end,
 	    [C1];				%Skip the rest
-	{no,_Suc} ->
-	    clauses_1(E, Cs, Ctxt, Sub);	%Skip this clause
-	{_Mat,no} ->
+	{_Mat,no} ->				%Guard fails.
 	    add_warning(C1, nomatch_guard),
-	    clauses_1(E, Cs, Ctxt, Sub);	%Skip this clause
+	    clauses(E, Cs, Ctxt, Sub, LitExpr);	%Skip this clause
 	{_Mat,_Suc} ->
-	    [C1|clauses_1(E, Cs, Ctxt, Sub)]
+	    [C1|clauses(E, Cs, Ctxt, Sub, LitExpr)]
     end;
-clauses_1(_, [], _, _) -> [].
+clauses(_, [], _, _, _) -> [].
 
 shadow_warning([C|Cs], none) ->
     add_warning(C, nomatch_shadow),
@@ -1649,69 +1678,18 @@ will_succeed(#c_literal{val=true}) -> yes;
 will_succeed(#c_literal{val=false}) -> no;
 will_succeed(_Guard) -> maybe.
 
-%% will_match(Expr, [Pattern]) -> yes | maybe | no.
-%%  Test if we know whether a match will succeed/fail or just don't
-%%  know.  Be conservative.
+%% will_match(Expr, [Pattern]) -> yes | maybe.
+%%  We KNOW that this function is only used after optimizations
+%%  in case_opt/4. Therefore clauses that can definitely not match
+%%  have already been pruned.
 
 will_match(#c_values{es=Es}, Ps) ->
-    will_match_list(Es, Ps, yes);
+    will_match_1(cerl_clauses:match_list(Ps, Es));
 will_match(E, [P]) ->
-    will_match_1(E, P).
-
-will_match_1(_E, #c_var{}) -> yes;		%Will always match
-will_match_1(E, #c_alias{pat=P}) ->		%Pattern decides
-    will_match_1(E, P);
-will_match_1(#c_var{}, _P) -> maybe;
-will_match_1(#c_tuple{es=Es}, #c_tuple{es=Ps}) ->
-    will_match_list(Es, Ps, yes);
-will_match_1(#c_literal{val=Lit}, P) ->
-    will_match_lit(Lit, P);
-will_match_1(_, _) -> maybe.
-
-will_match_list([E|Es], [P|Ps], M) ->
-    case will_match_1(E, P) of
-	yes -> will_match_list(Es, Ps, M);
-	maybe -> will_match_list(Es, Ps, maybe);
-	no -> no
-    end;
-will_match_list([], [], M) -> M.
-
-will_match_lit(Cons, #c_cons{hd=Hp,tl=Tp}) ->
-    case Cons of
-	[H|T] ->
-	    case will_match_lit(H, Hp) of
-		yes -> will_match_lit(T, Tp);
-		Other -> Other
-	    end;
-	_ ->
-	    no
-    end;
-will_match_lit(Tuple, #c_tuple{es=Es}) ->
-    case is_tuple(Tuple) andalso tuple_size(Tuple) =:= length(Es) of
-	true -> will_match_lit_list(tuple_to_list(Tuple), Es);
-	false -> no
-    end;
-will_match_lit(Bin, #c_binary{}) ->
-    case is_bitstring(Bin) of
-	true -> maybe;
-	false -> no
-    end;
-will_match_lit(_, #c_var{}) ->
-    yes;
-will_match_lit(Lit, #c_alias{pat=P}) ->
-    will_match_lit(Lit, P);
-will_match_lit(Lit1, #c_literal{val=Lit2}) ->
-    case Lit1 =:= Lit2 of
-	true -> yes;
-	false -> no
-    end.
+    will_match_1(cerl_clauses:match(P, E)).
 
-will_match_lit_list([H|T], [P|Ps]) ->
-    case will_match_lit(H, P) of
-	yes -> will_match_lit_list(T, Ps);
-	Other -> Other
-    end;
-will_match_lit_list([], []) -> yes.
+will_match_1({false,_}) -> maybe;
+will_match_1({true,_}) -> yes.
 
 %% opt_bool_case(CoreExpr) - CoreExpr'.
 %%  Do various optimizations to case statement that has a
@@ -1910,166 +1888,243 @@ opt_bool_case_guard(Arg, [#c_clause{pats=[#c_literal{val=false}]}=Fc,Tc]) ->
 %%  last clause is guaranteed to match so if there is only one clause
 %%  with a pattern containing only variables then rewrite to a let.
 
-eval_case(#c_case{arg=#c_var{name=V},
-		  clauses=[#c_clause{pats=[P],guard=G,body=B}|_]}=Case,
-	  #sub{t=Tdb}=Sub) ->
-    case orddict:find(V, Tdb) of
-	{ok,Type} ->
-	    case {will_match_type(P, Type),will_succeed(G)} of
-		{yes,yes} ->
-		    {Ps,Es} = remove_non_vars(P, Type),
-		    expr(#c_let{vars=Ps,arg=#c_values{es=Es},body=B},
-			 sub_new(Sub));
-		{_,_} ->
-		    eval_case_1(Case, Sub)
-	    end;
-	error -> eval_case_1(Case, Sub)
-    end;
-eval_case(Case, Sub) -> eval_case_1(Case, Sub).
-
-eval_case_1(#c_case{arg=E,clauses=[#c_clause{pats=Ps,body=B}]}=Case, Sub) ->
-    case is_var_pat(Ps) of
-	true -> expr(#c_let{vars=Ps,arg=E,body=B}, sub_new(Sub));
-	false -> eval_case_2(E, Ps, B, Case)
-    end;
-eval_case_1(Case, _) -> Case.
-
-eval_case_2(E, [P], B, Case) ->
-    %% Recall that there is only one clause and that it is guaranteed to match.
-    %%   If E and P are literals, they must be the same literal and the body
-    %% can be used directly as there are no variables that need to be bound.
-    %%   Otherwise, P could be an alias meaning that two or more variables
-    %% would be bound to E. We don't bother to optimize that case as it
-    %% is rather uncommon.
-    case core_lib:is_literal(E) andalso core_lib:is_literal(P) of
-	false -> Case;
-	true -> B
-    end;
-eval_case_2(_, _, _, Case) -> Case.
-
-is_var_pat(Ps) ->
-    all(fun (#c_var{}) -> true;
-	    (_Pat) -> false
-	end, Ps).
-
-will_match_type(#c_tuple{es=Es}, #c_tuple{es=Ps}) ->
-    will_match_list_type(Es, Ps);
-will_match_type(#c_literal{val=Atom}, #c_literal{val=Atom}) -> yes;
-will_match_type(#c_var{}, #c_var{}) -> yes;
-will_match_type(#c_var{}, #c_alias{}) -> yes;
-will_match_type(_, _) -> no.
-
-will_match_list_type([E|Es], [P|Ps]) ->
-    case will_match_type(E, P) of
-	yes -> will_match_list_type(Es, Ps);
-	no -> no
-    end;
-will_match_list_type([], []) -> yes;
-will_match_list_type(_, _) -> no.		%Different length
-
-remove_non_vars(Ps0, Es0) ->
-    {Ps,Es} = remove_non_vars(Ps0, Es0, [], []),
-    {reverse(Ps),reverse(Es)}.
-
-remove_non_vars(#c_tuple{es=Ps}, #c_tuple{es=Es}, Pacc, Eacc) ->
-    remove_non_vars_list(Ps, Es, Pacc, Eacc);
-remove_non_vars(#c_var{}=Var, #c_alias{var=Evar}, Pacc, Eacc) ->
-    {[Var|Pacc],[Evar|Eacc]};
-remove_non_vars(#c_var{}=Var, #c_var{}=Evar, Pacc, Eacc) ->
-    {[Var|Pacc],[Evar|Eacc]};
-remove_non_vars(P, E, Pacc, Eacc) ->
-    true = core_lib:is_literal(P) andalso core_lib:is_literal(E), %Assertion.
-    {Pacc,Eacc}.
-
-remove_non_vars_list([P|Ps], [E|Es], Pacc0, Eacc0) ->
-    {Pacc,Eacc} = remove_non_vars(P, E, Pacc0, Eacc0),
-    remove_non_vars_list(Ps, Es, Pacc, Eacc);
-remove_non_vars_list([], [], Pacc, Eacc) ->
-    {Pacc,Eacc}.
+eval_case(#c_case{arg=E,clauses=[#c_clause{pats=Ps0,body=B}]}, Sub) ->
+    Es = case cerl:is_c_values(E) of
+	     true -> cerl:values_es(E);
+	     false -> [E]
+	 end,
+    {true,Bs} = cerl_clauses:match_list(Ps0, Es),
+    {Ps,As} = unzip(Bs),
+    expr(#c_let{vars=Ps,arg=core_lib:make_values(As),body=B}, sub_new(Sub));
+eval_case(Case, _) -> Case.
 
 %% case_opt(CaseArg, [Clause]) -> {CaseArg,[Clause]}.
-%%  Try and optimise case by avoid building a tuple in
-%%  the case expression. Instead of building a tuple
-%%  in the case expression, combine the elements into
-%%  multiple "values". If a clause refers to the tuple
-%%  in the case expression (that was not built), introduce
-%%  a let into the guard and/or body to build the tuple.
+%%  Try and optimise a case by avoid building tuples or lists
+%%  in the case expression. Instead combine the variable parts
+%%  of the case expression to multiple "values". If a clause
+%%  refers to the constructed term in the case expression (which
+%%  was not built), introduce a let into the guard and/or body to
+%%  build the term.
 %%
-%%     case {Expr1,Expr2} of		 case <Expr1,Expr2> of
-%%         {P1,P2} -> ...		     <P1,P2> -> ...
+%%     case {ok,[Expr1,Expr2]} of	case <Expr1,Expr2> of
+%%         {ok,[P1,P2]} -> ...		    <P1,P2> -> ...
 %%          .  	       	       	  ==>        .
 %%          .				     .
 %%          .				     .
-%%         Var ->                            <Var1,Var2> ->
-%%             ... Var ...                      let <Var> = {Var1,Var2}
-%%                                                  in ... Var ...
+%%         Var ->                           <Var1,Var2> ->
+%%             ... Var ...                     let <Var> = {ok,[Var1,Var2]}
+%%                                                 in ... Var ...
 %%          .                                 .
 %%          .                                 .
 %%          .				      .
-%%     end.				 end.
+%%     end.				end.
 %%
-case_opt(#c_tuple{anno=A,es=Es}, Cs0) ->
-    Cs1 = case_opt_cs(Cs0, length(Es)),
-    {core_lib:set_anno(core_lib:make_values(Es), A),Cs1};
-case_opt(Arg, Cs) -> {Arg,Cs}.
-
-case_opt_cs([#c_clause{pats=Ps0,guard=G,body=B}=C|Cs], Arity) ->
-    case case_tuple_pat(Ps0, Arity) of
-	{ok,Ps1,Avs} ->
-	    Flet = fun ({V,Pat}, Body) -> letify(V, Pat, Body) end,
-	    [C#c_clause{pats=Ps1,
-			guard=foldl(Flet, G, Avs),
-			body=foldl(Flet, B, Avs)}|case_opt_cs(Cs, Arity)];
-	error ->				%Can't match
-	    add_warning(C, nomatch_clause_type),
-	    case_opt_cs(Cs, Arity)
+case_opt(Arg, Cs0, Sub) ->
+    Cs1 = [{cerl:clause_pats(C),C,[],[]} || C <- Cs0],
+    Args0 = case cerl:is_c_values(Arg) of
+		false -> [Arg];
+		true -> cerl:values_es(Arg)
+	    end,
+    LitExpr = cerl:is_literal(Arg),
+    {Args,Cs2} = case_opt_args(Args0, Cs1, Sub, LitExpr, []),
+    Cs = [cerl:update_c_clause(C,
+			       reverse(Ps),
+			       letify(Bs, cerl:clause_guard(C)),
+			       letify(Bs, cerl:clause_body(C))) ||
+	     {[],C,Ps,Bs} <- Cs2],
+    {core_lib:make_values(Args),Cs}.
+
+case_opt_args([A0|As0], Cs0, Sub, LitExpr, Acc) ->
+    case case_opt_arg(A0, Sub, Cs0, LitExpr) of
+	error ->
+	    %% Nothing to be done. Move on to the next argument.
+	    Cs = [{Ps,C,[P|PsAcc],Bs} || {[P|Ps],C,PsAcc,Bs} <- Cs0],
+	    case_opt_args(As0, Cs, Sub, LitExpr, [A0|Acc]);
+	{ok,As1,Cs} ->
+	    %% The argument was either expanded (from tuple/list) or
+	    %% removed (literal).
+	    case_opt_args(As1++As0, Cs, Sub, LitExpr, Acc)
+    end;
+case_opt_args([], Cs, _Sub, _LitExpr, Acc) ->
+    {reverse(Acc),Cs}.
+
+%% case_opt_arg(Expr, Sub, Clauses0, LitExpr) ->
+%%         {ok,Args,Clauses} | error
+%%  Try to expand one argument to several arguments (if tuple/list)
+%%  or to remove a literal argument.
+%%
+case_opt_arg(E0, Sub, Cs, LitExpr) ->
+    E = maybe_replace_var(E0, Sub),
+    case cerl:is_data(E) of
+	false ->
+	    error;
+	true ->
+	    case cerl:data_type(E) of
+		{atomic,_} ->
+		    case_opt_lit(E, Cs, LitExpr);
+		_ ->
+		    case_opt_data(E, Cs, LitExpr)
+	    end
+    end.
+
+%% maybe_replace_var(Expr0, Sub) -> Expr
+%%  If Expr0 is a variable that has been previously matched and
+%%  is known to be a tuple, return the tuple instead. Otherwise
+%%  return Expr0 unchanged.
+%%
+maybe_replace_var(E, Sub) ->
+    case cerl:is_c_var(E) of
+	false -> E;
+	true -> maybe_replace_var_1(E, Sub)
+    end.
+
+maybe_replace_var_1(E, #sub{t=Tdb}) ->
+    case orddict:find(cerl:var_name(E), Tdb) of
+	{ok,T0} ->
+	    case cerl:is_c_tuple(T0) of
+		false ->
+		    E;
+		true ->
+		    cerl_trees:map(fun(C) ->
+					   case cerl:is_c_alias(C) of
+					       false -> C;
+					       true -> cerl:alias_pat(C)
+					   end
+				   end, T0)
+	    end;
+	error ->
+	    E
+    end.
+
+%% case_opt_lit(Literal, Clauses0, LitExpr) ->
+%%           {ok,[],Clauses} | error
+%%  The current part of the case expression is a literal. That
+%%  means that we will know at compile-time whether a clause
+%%  will match, and we can remove the corresponding pattern from
+%%  each clause.
+%%
+%%  The only complication is if the literal is a binary. Binary
+%%  pattern matching is tricky, so we will give up in that case.
+
+case_opt_lit(Lit, Cs0, LitExpr) ->
+    try case_opt_lit_1(Cs0, Lit, LitExpr) of
+	Cs ->
+	    {ok,[],Cs}
+    catch
+	throw:impossible ->
+	    error
+    end.
+
+case_opt_lit_1([{[P|Ps],C,PsAcc,Bs0}|Cs], E, LitExpr) ->
+    case cerl_clauses:match(P, E) of
+	none ->
+	    %% The pattern will not match the literal. Remove the clause.
+	    %% Unless the entire case expression is a literal, also
+	    %% emit a warning.
+	    case LitExpr of
+		false -> add_warning(C, nomatch_clause_type);
+		true -> ok
+	    end,
+	    case_opt_lit_1(Cs, E, LitExpr);
+	{true,Bs} ->
+	    %% The pattern matches the literal. Remove the pattern
+	    %% and update the bindings.
+	    [{Ps,C,PsAcc,Bs++Bs0}|case_opt_lit_1(Cs, E, LitExpr)];
+	{false,_} ->
+	    %% Binary literal and pattern. We are not sure whether
+	    %% the pattern will match.
+	    throw(impossible)
+    end;
+case_opt_lit_1([], _, _) -> [].
+
+%% case_opt_data(Expr, Clauses0, LitExpr) -> {ok,Exprs,Clauses}
+
+case_opt_data(E, Cs0, LitExpr) ->
+    Es = cerl:data_es(E),
+    Cs = case_opt_data_1(Cs0, Es,
+			 {cerl:data_type(E),cerl:data_arity(E)},
+			 LitExpr),
+    {ok,Es,Cs}.
+
+case_opt_data_1([{[P|Ps0],C,PsAcc,Bs0}|Cs], Es, TypeSig, LitExpr) ->
+    case case_data_pat(P, TypeSig) of
+	{ok,Ps1,Bs1} ->
+	    [{Ps1++Ps0,C,PsAcc,Bs1++Bs0}|
+	     case_opt_data_1(Cs, Es, TypeSig,LitExpr)];
+	error ->
+	    case LitExpr of
+		false -> add_warning(C, nomatch_clause_type);
+		true -> ok
+	    end,
+	    case_opt_data_1(Cs, Es, TypeSig, LitExpr)
     end;
-case_opt_cs([], _) -> [].
+case_opt_data_1([], _, _, _) -> [].
 
-%% case_tuple_pat([Pattern], Arity) -> {ok,[Pattern],[{AliasVar,Pat}]} | error.
+%% case_data_pat(Pattern, Type, Arity) -> {ok,[Pattern],[{AliasVar,Pat}]} | error.
 
-case_tuple_pat([#c_tuple{es=Ps}], Arity) when length(Ps) =:= Arity ->
-    {ok,Ps,[]};
-case_tuple_pat([#c_literal{val=T}], Arity) when tuple_size(T) =:= Arity ->
-    Ps = [#c_literal{val=E} || E <- tuple_to_list(T)],
-    {ok,Ps,[]};
-case_tuple_pat([#c_var{anno=Anno0}=V], Arity) ->
-    Vars = make_vars(Anno0, 1, Arity),
+case_data_pat(P, TypeSig) ->
+    case cerl:is_data(P) of
+	false ->
+	    case_data_pat_var(P, TypeSig);
+	true ->
+	    case {cerl:data_type(P),cerl:data_arity(P)} of
+		TypeSig ->
+		    {ok,cerl:data_es(P),[]};
+		{_,_} ->
+		    error
+	    end
+    end.
 
+%% case_data_pat_var(Pattern, {DataType,ArityType}) ->
+%%          {ok,[Pattern],[{AliasVar,Pat}]}
+
+case_data_pat_var(P, {Type,Arity}=TypeSig) ->
     %% If the entire case statement is evaluated in an effect
     %% context (e.g. "case {A,B} of ... end, ok"), there will
     %% be a warning that a term is constructed but never used.
-    %% To avoid that warning, we must annotate the tuple as
-    %% compiler generated.
-
-    Anno = [compiler_generated|Anno0],
-    {ok,Vars,[{V,#c_tuple{anno=Anno,es=Vars}}]};
-case_tuple_pat([#c_alias{var=V,pat=P}], Arity) ->
-    case case_tuple_pat([P], Arity) of
-	{ok,Ps,Avs} ->
-	    Anno0 = core_lib:get_anno(P),
-	    Anno = [compiler_generated|Anno0],
-	    {ok,Ps,[{V,#c_tuple{anno=Anno,es=unalias_pat_list(Ps)}}|Avs]};
-	error ->
+    %% To avoid that warning, we must annotate the data
+    %% constructor as compiler generated.
+    Ann = [compiler_generated|cerl:get_ann(P)],
+    case cerl:type(P) of
+	var ->
+	    Vars = make_vars(cerl:get_ann(P), Arity),
+	    {ok,Vars,[{P,cerl:ann_make_data(Ann, Type, Vars)}]};
+	alias ->
+	    V = cerl:alias_var(P),
+	    Apat = cerl:alias_pat(P),
+	    case case_data_pat(Apat, TypeSig) of
+		{ok,Ps,Bs} ->
+		    {ok,Ps,[{V,cerl:ann_make_data(Ann, Type, unalias_pat_list(Ps))}|Bs]};
+		error ->
+		    error
+	    end;
+	_ ->
 	    error
-    end;
-case_tuple_pat(_, _) -> error.
+    end.
 
 %% unalias_pat(Pattern) -> Pattern.
 %%  Remove all the aliases in a pattern but using the alias variables
 %%  instead of the values.  We KNOW they will be bound.
 
-unalias_pat(#c_alias{var=V}) -> V;
-unalias_pat(#c_cons{anno=Anno,hd=H0,tl=T0}) ->
-    H1 = unalias_pat(H0),
-    T1 = unalias_pat(T0),
-    ann_c_cons(Anno, H1, T1);
-unalias_pat(#c_tuple{anno=Anno,es=Ps}) ->
-    ann_c_tuple(Anno, unalias_pat_list(Ps));
-unalias_pat(Atomic) -> Atomic.
+unalias_pat(P) ->
+    case cerl:is_c_alias(P) of
+	true ->
+	    cerl:alias_var(P);
+	false ->
+	    case cerl:is_data(P) of
+		false ->
+		    P;
+		true ->
+		    Es = unalias_pat_list(cerl:data_es(P)),
+		    cerl:update_data(P, cerl:data_type(P), Es)
+	    end
+    end.
 
 unalias_pat_list(Ps) -> [unalias_pat(P) || P <- Ps].
 
+make_vars(A, Max) ->
+    make_vars(A, 1, Max).
+
 make_vars(A, I, Max) when I =< Max ->
     [make_var(A)|make_vars(A, I+1, Max)];
 make_vars(_, _, _) -> [].
@@ -2082,6 +2137,11 @@ make_var_name() ->
     put(new_var_num, N+1),
     list_to_atom("fol"++integer_to_list(N)).
 
+letify(Bs, Body) ->
+    foldr(fun({V,Val}, B) ->
+		  letify(V, Val, B)
+	  end, Body, Bs).
+
 letify(#c_var{name=Vname}=Var, Val, Body) ->
     case core_lib:is_var_used(Vname, Body) of
 	true ->
@@ -2102,7 +2162,7 @@ opt_case_in_let_0([#c_var{name=V}], Arg,
 	    case is_simple_case_arg(Arg) andalso
 		not core_lib:is_var_used(V, Case#c_case{arg=#c_literal{val=nil}}) of
 		true ->
-		    opt_bool_case(Case#c_case{arg=Arg});
+		    expr(opt_bool_case(Case#c_case{arg=Arg,clauses=Cs}), sub_new());
 		false ->
 		    Let
 	    end;
diff --git a/lib/compiler/test/core_fold_SUITE.erl b/lib/compiler/test/core_fold_SUITE.erl
index a5a4e62a42..69f61a046f 100644
--- a/lib/compiler/test/core_fold_SUITE.erl
+++ b/lib/compiler/test/core_fold_SUITE.erl
@@ -249,6 +249,12 @@ coverage(Config) when is_list(Config) ->
     case list_to_pid("<0.42.0>") of
 	Pid when is_pid(Pid) -> ok
     end,
+
+    %% Cover the non-variable case in bsm_do_an/4.
+    ok = bsm_an_inlined(<<1>>, Config),
+    error = bsm_an_inlined(<<1,2,3>>, Config),
+    error = bsm_an_inlined([], Config),
+
     ok.
 
 cover_will_match_list_type(A) ->
@@ -290,6 +296,9 @@ cover_is_safe_bool_expr(X) ->
 	    false
     end.
 
+bsm_an_inlined(<<_:8>>, _) -> ok;
+bsm_an_inlined(_, _) -> error.
+
 id(I) -> I.
 
 unused_multiple_values_error(Config) when is_list(Config) ->
diff --git a/lib/compiler/test/warnings_SUITE.erl b/lib/compiler/test/warnings_SUITE.erl
index 810b2b48c9..7186956603 100644
--- a/lib/compiler/test/warnings_SUITE.erl
+++ b/lib/compiler/test/warnings_SUITE.erl
@@ -117,6 +117,7 @@ pattern2(Config) when is_list(Config) ->
 	   Source,
 	   [nowarn_unused_vars],
 	   {warnings,[{2,sys_core_fold,{nomatch_shadow,1}},
+		      {4,sys_core_fold,no_clause_match},
 		      {5,sys_core_fold,nomatch_clause_type},
 		      {6,sys_core_fold,nomatch_clause_type}]}}],
     ?line [] = run(Config, Ts),