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-rw-r--r--lib/compiler/src/sys_core_fold.erl143
1 files changed, 70 insertions, 73 deletions
diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl
index 09716d0866..2158c29576 100644
--- a/lib/compiler/src/sys_core_fold.erl
+++ b/lib/compiler/src/sys_core_fold.erl
@@ -2040,17 +2040,18 @@ case_opt_args([], Cs, _Sub, _LitExpr, Acc) ->
%% Try to expand one argument to several arguments (if tuple/list)
%% or to remove a literal argument.
%%
-case_opt_arg(E0, Sub, Cs, LitExpr) ->
+case_opt_arg(E0, Sub, Cs0, LitExpr) ->
E = maybe_replace_var(E0, Sub),
case cerl:is_data(E) of
false ->
- {error,Cs};
+ {error,Cs0};
true ->
+ Cs = case_opt_nomatch(E, Cs0, LitExpr),
case cerl:data_type(E) of
{atomic,_} ->
- case_opt_lit(E, Cs, LitExpr);
+ case_opt_lit(E, Cs);
_ ->
- case_opt_data(E, Cs, LitExpr)
+ case_opt_data(E, Cs)
end
end.
@@ -2113,8 +2114,26 @@ coerce_to_data(C) ->
coerce_to_data(cerl:alias_pat(C))
end.
-%% case_opt_lit(Literal, Clauses0, LitExpr) ->
-%% {ok,[],Clauses} | error
+%% case_opt_nomatch(E, Clauses, LitExpr) -> Clauses'
+%% Remove all clauses that cannot possibly match.
+
+case_opt_nomatch(E, [{[P|_],C,_,_}=Current|Cs], LitExpr) ->
+ case cerl_clauses:match(P, E) of
+ none ->
+ %% The pattern will not match the case expression. 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_nomatch(E, Cs, LitExpr);
+ _ ->
+ [Current|case_opt_nomatch(E, Cs, LitExpr)]
+ end;
+case_opt_nomatch(_, [], _) -> [].
+
+%% case_opt_lit(Literal, Clauses0) -> {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
@@ -2123,68 +2142,48 @@ coerce_to_data(C) ->
%% 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) ->
- Cs1 = case_opt_lit_1(Lit, Cs0, LitExpr),
- try case_opt_lit_2(Lit, Cs1) of
+case_opt_lit(Lit, Cs0) ->
+ try case_opt_lit_1(Lit, Cs0) of
Cs ->
{ok,[],Cs}
catch
throw:impossible ->
- {error,Cs1}
+ {error,Cs0}
end.
-case_opt_lit_1(E, [{[P|_],C,_,_}=Current|Cs], 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(E, Cs, LitExpr);
- _ ->
- [Current|case_opt_lit_1(E, Cs, LitExpr)]
- end;
-case_opt_lit_1(_, [], _) -> [].
-
-case_opt_lit_2(E, [{[P|Ps],C,PsAcc,Bs0}|Cs]) ->
- %% Non-matching clauses have already been removed in case_opt_lit_1/3.
+case_opt_lit_1(E, [{[P|Ps],C,PsAcc,Bs0}|Cs]) ->
+ %% Non-matching clauses have already been removed
+ %% in case_opt_nomatch/3.
case cerl_clauses:match(P, E) of
{true,Bs} ->
%% The pattern matches the literal. Remove the pattern
%% and update the bindings.
- [{Ps,C,PsAcc,Bs++Bs0}|case_opt_lit_2(E, Cs)];
+ [{Ps,C,PsAcc,Bs++Bs0}|case_opt_lit_1(E, Cs)];
{false,_} ->
%% Binary literal and pattern. We are not sure whether
%% the pattern will match.
throw(impossible)
end;
-case_opt_lit_2(_, []) -> [].
+case_opt_lit_1(_, []) -> [].
%% case_opt_data(Expr, Clauses0, LitExpr) -> {ok,Exprs,Clauses}
-case_opt_data(E, Cs0, LitExpr) ->
+case_opt_data(E, Cs0) ->
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_data_1([], _, _, _) -> [].
+ TypeSig = {cerl:data_type(E),cerl:data_arity(E)},
+ try case_opt_data_1(Cs0, Es, TypeSig) of
+ Cs ->
+ {ok,Es,Cs}
+ catch
+ throw:impossible ->
+ {error,Cs0}
+ end.
+
+case_opt_data_1([{[P|Ps0],C,PsAcc,Bs0}|Cs], Es, TypeSig) ->
+ {ok,Ps1,Bs1} = case_data_pat(P, TypeSig),
+ [{Ps1++Ps0,C,PsAcc,Bs1++Bs0}|
+ case_opt_data_1(Cs, Es, TypeSig)];
+case_opt_data_1([], _, _) -> [].
%% case_data_pat(Pattern, Type, Arity) -> {ok,[Pattern],[{AliasVar,Pat}]} | error.
@@ -2193,12 +2192,7 @@ case_data_pat(P, TypeSig) ->
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
+ {ok,cerl:data_es(P),[]}
end.
%% case_data_pat_var(Pattern, {DataType,ArityType}) ->
@@ -2218,35 +2212,38 @@ case_data_pat_var(P, {Type,Arity}=TypeSig) ->
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
+ {ok,Ps,Bs} = case_data_pat(Apat, TypeSig),
+ {ok,Ps,[{V,cerl:ann_make_data(Ann, Type,
+ pat_to_expr_list(Ps))}|Bs]}
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.
+%% pat_to_expr(Pattern) -> Expression.
+%% Convert a pattern to an expression if possible. We KNOW that
+%% all variables in the pattern will be bound.
+%%
+%% Throw an 'impossible' exception if a map or (non-literal)
+%% binary is encountered. Trying to use a map pattern as an
+%% expression is incorrect, while rebuilding a potentially
+%% huge binary in an expression would be wasteful.
-unalias_pat(P) ->
- case cerl:is_c_alias(P) of
- true ->
+pat_to_expr(P) ->
+ case cerl:type(P) of
+ alias ->
cerl:alias_var(P);
- false ->
+ var ->
+ P;
+ _ ->
case cerl:is_data(P) of
false ->
- P;
+ %% Map or binary.
+ throw(impossible);
true ->
- Es = unalias_pat_list(cerl:data_es(P)),
+ Es = pat_to_expr_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].
+pat_to_expr_list(Ps) -> [pat_to_expr(P) || P <- Ps].
make_vars(A, Max) ->
make_vars(A, 1, Max).
generated by cgit v1.2.3 (git 2.25.1) at 2024-10-30 04:42:10 +0000