diff options
Diffstat (limited to 'lib/compiler/src')
| -rw-r--r-- | lib/compiler/src/sys_core_fold.erl | 37 |
1 files changed, 27 insertions, 10 deletions
diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl index f17b0bd130..fbd7452301 100644 --- a/lib/compiler/src/sys_core_fold.erl +++ b/lib/compiler/src/sys_core_fold.erl @@ -2672,16 +2672,19 @@ bsm_nonempty([#c_clause{pats=Ps}|Cs], Pos) -> bsm_nonempty([], _ ) -> false. %% bsm_ensure_no_partition(Cs, Pos) -> ok (exception if problem) -%% We must make sure that binary matching is not partitioned between +%% We must make sure that matching is not partitioned between %% variables like this: %% foo(<<...>>) -> ... -%% foo(Var) when ... -> ... -%% foo(<<...>>) -> +%% foo(<Variable>) when ... -> ... +%% foo(<Any non-variable pattern>) -> %% If there is such partition, we are not allowed to reuse the binary variable -%% for the match context. Also, arguments to the left of the argument that -%% is matched against a binary, are only allowed to be simple variables, not -%% used in guards. The reason is that we must know that the binary is only -%% matched in one place. +%% for the match context. +%% +%% Also, arguments to the left of the argument that is matched +%% against a binary, are only allowed to be simple variables, not +%% used in guards. The reason is that we must know that the binary is +%% only matched in one place (i.e. there must be only one bs_start_match2 +%% instruction emitted). bsm_ensure_no_partition(Cs, Pos) -> bsm_ensure_no_partition_1(Cs, Pos, before). @@ -2689,6 +2692,12 @@ bsm_ensure_no_partition(Cs, Pos) -> %% Loop through each clause. bsm_ensure_no_partition_1([#c_clause{pats=Ps,guard=G}|Cs], Pos, State0) -> State = bsm_ensure_no_partition_2(Ps, Pos, G, simple_vars, State0), + case State of + 'after' -> + bsm_ensure_no_partition_after(Cs, Pos); + _ -> + ok + end, bsm_ensure_no_partition_1(Cs, Pos, State); bsm_ensure_no_partition_1([], _, _) -> ok. @@ -2698,8 +2707,7 @@ bsm_ensure_no_partition_2([#c_binary{}=Where|_], 1, _, Vstate, State) -> before when Vstate =:= simple_vars -> within; before -> bsm_problem(Where, Vstate); within when Vstate =:= simple_vars -> within; - within -> bsm_problem(Where, Vstate); - 'after' -> bsm_problem(Where, bin_partition) + within -> bsm_problem(Where, Vstate) end; bsm_ensure_no_partition_2([#c_alias{}=Alias|_], 1, N, Vstate, State) -> %% Retrieve the real pattern that the alias refers to and check that. @@ -2748,6 +2756,15 @@ bsm_ensure_no_partition_2([#c_var{name=V}|Ps], N, G, Vstate, S) -> bsm_ensure_no_partition_2([_|Ps], N, G, _, S) -> bsm_ensure_no_partition_2(Ps, N-1, G, bin_argument_order, S). +bsm_ensure_no_partition_after([#c_clause{pats=Ps}|Cs], Pos) -> + case nth(Pos, Ps) of + #c_var{} -> + bsm_ensure_no_partition_after(Cs, Pos); + P -> + bsm_problem(P, bin_partition) + end; +bsm_ensure_no_partition_after([], _) -> ok. + bsm_could_match_binary(#c_alias{pat=P}) -> bsm_could_match_binary(P); bsm_could_match_binary(#c_cons{}) -> false; bsm_could_match_binary(#c_tuple{}) -> false; @@ -2872,7 +2889,7 @@ format_error(useless_building) -> format_error(bin_opt_alias) -> "INFO: the '=' operator will prevent delayed sub binary optimization"; format_error(bin_partition) -> - "INFO: non-consecutive clauses that match binaries " + "INFO: matching non-variables after a previous clause matching a variable " "will prevent delayed sub binary optimization"; format_error(bin_left_var_used_in_guard) -> "INFO: a variable to the left of the binary pattern is used in a guard; " |