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-rw-r--r--lib/compiler/src/beam_validator.erl102
-rw-r--r--lib/compiler/test/beam_validator_SUITE_data/receive_stacked.S4
2 files changed, 67 insertions, 39 deletions
diff --git a/lib/compiler/src/beam_validator.erl b/lib/compiler/src/beam_validator.erl
index 42d5f0ce4c..de1a87039b 100644
--- a/lib/compiler/src/beam_validator.erl
+++ b/lib/compiler/src/beam_validator.erl
@@ -802,24 +802,14 @@ valfun_4({set_tuple_element,Src,Tuple,N}, Vst) ->
Es = set_element_type({integer,I}, get_term_type(Src, Vst), Es0),
override_type({tuple, Sz, Es}, Tuple, Vst);
%% Match instructions.
-valfun_4({select_val,Src,{f,Fail},{list,Choices}}, Vst0) ->
- assert_term(Src, Vst0),
+valfun_4({select_val,Src,{f,Fail},{list,Choices}}, Vst) ->
+ assert_term(Src, Vst),
assert_choices(Choices),
- Vst = select_val_branches(Choices, Src, Vst0),
- branch(Fail, Vst,
- fun(SuccVst) ->
- %% The next instruction is never executed.
- kill_state(SuccVst)
- end);
-valfun_4({select_tuple_arity,Tuple,{f,Fail},{list,Choices}}, Vst0) ->
- assert_type(tuple, Tuple, Vst0),
+ validate_select_val(Fail, Choices, Src, Vst);
+valfun_4({select_tuple_arity,Tuple,{f,Fail},{list,Choices}}, Vst) ->
+ assert_type(tuple, Tuple, Vst),
assert_arities(Choices),
- Vst = select_arity_branches(Choices, Tuple, Vst0),
- branch(Fail, Vst,
- fun(SuccVst) ->
- %% The next instruction is never executed.
- kill_state(SuccVst)
- end);
+ validate_select_tuple_arity(Fail, Choices, Tuple, Vst);
%% New bit syntax matching instructions.
valfun_4({test,bs_start_match3,{f,Fail},Live,[Src],Dst}, Vst) ->
@@ -1558,7 +1548,11 @@ bsm_restore(Reg, SavePoint, Vst) ->
_ -> error({illegal_restore,SavePoint,range})
end.
-select_val_branches([Val,{f,L}|T], Src, Vst0) ->
+validate_select_val(_Fail, _Choices, _Src, #vst{current=none}=Vst) ->
+ %% We've already branched on all of Src's possible values, so we know we
+ %% can't reach the fail label or any of the remaining choices.
+ Vst;
+validate_select_val(Fail, [Val,{f,L}|T], Src, Vst0) ->
Vst = branch(L, Vst0,
fun(BranchVst) ->
update_eq_types(Src, Val, BranchVst)
@@ -1566,22 +1560,34 @@ select_val_branches([Val,{f,L}|T], Src, Vst0) ->
fun(FailVst) ->
update_ne_types(Src, Val, FailVst)
end),
- select_val_branches(T, Src, Vst);
-select_val_branches([], _, Vst) ->
- Vst.
+ validate_select_val(Fail, T, Src, Vst);
+validate_select_val(Fail, [], _, Vst) ->
+ branch(Fail, Vst,
+ fun(SuccVst) ->
+ %% The next instruction is never executed.
+ kill_state(SuccVst)
+ end).
-select_arity_branches([SzA,{f,L}|T], Tuple, Vst0) ->
+validate_select_tuple_arity(_Fail, _Choices, _Src, #vst{current=none}=Vst) ->
+ %% We've already branched on all of Src's possible values, so we know we
+ %% can't reach the fail label or any of the remaining choices.
+ Vst;
+validate_select_tuple_arity(Fail, [Arity,{f,L}|T], Tuple, Vst0) ->
+ Type = {tuple, Arity, #{}},
Vst = branch(L, Vst0,
fun(BranchVst) ->
- update_type(fun meet/2, {tuple,SzA,#{}},
- Tuple, BranchVst)
+ update_type(fun meet/2, Type, Tuple, BranchVst)
end,
fun(FailVst) ->
- FailVst
+ update_type(fun subtract/2, Type, Tuple, FailVst)
end),
- select_arity_branches(T, Tuple, Vst);
-select_arity_branches([], _, #vst{}=Vst) ->
- Vst.
+ validate_select_tuple_arity(Fail, T, Tuple, Vst);
+validate_select_tuple_arity(Fail, [], _, #vst{}=Vst) ->
+ branch(Fail, Vst,
+ fun(SuccVst) ->
+ %% The next instruction is never executed.
+ kill_state(SuccVst)
+ end).
infer_types({Kind,_}=Reg, Vst) when Kind =:= x; Kind =:= y ->
infer_types(get_reg_vref(Reg, Vst), Vst);
@@ -1756,7 +1762,20 @@ update_type(Merge, With, Literal, Vst) ->
end.
update_ne_types(LHS, RHS, Vst) ->
- update_type(fun subtract/2, get_term_type(RHS, Vst), LHS, Vst).
+ %% While updating types on equality is fairly straightforward, inequality
+ %% is a bit trickier since all we know is that the *value* of LHS differs
+ %% from RHS, so we can't blindly subtract their types.
+ %%
+ %% Consider `number =/= {integer,[]}`; all we know is that LHS isn't equal
+ %% to some *specific integer* of unknown value, and if we were to subtract
+ %% {integer,[]} we would erroneously infer that the new type is {float,[]}.
+ %%
+ %% Therefore, we only subtract when we know that RHS has a specific value.
+ RType = get_term_type(RHS, Vst),
+ case is_literal(RType) of
+ true -> update_type(fun subtract/2, RType, LHS, Vst);
+ false -> Vst
+ end.
update_eq_types(LHS, RHS, Vst0) ->
Infer = infer_types(LHS, Vst0),
@@ -1867,16 +1886,24 @@ assert_movable(Src, Vst) ->
_ = get_movable_term_type(Src, Vst),
ok.
-assert_literal(nil) -> ok;
-assert_literal({atom,A}) when is_atom(A) -> ok;
-assert_literal({float,F}) when is_float(F) -> ok;
-assert_literal({integer,I}) when is_integer(I) -> ok;
-assert_literal({literal,_L}) -> ok;
-assert_literal(T) -> error({literal_required,T}).
+assert_literal(Src) ->
+ case is_literal(Src) of
+ true -> ok;
+ false -> error({literal_required,Src})
+ end.
+
+assert_not_literal(Src) ->
+ case is_literal(Src) of
+ true -> error({literal_not_allowed,Src});
+ false -> ok
+ end.
-assert_not_literal({x,_}) -> ok;
-assert_not_literal({y,_}) -> ok;
-assert_not_literal(Literal) -> error({literal_not_allowed,Literal}).
+is_literal(nil) -> true;
+is_literal({atom,A}) when is_atom(A) -> true;
+is_literal({float,F}) when is_float(F) -> true;
+is_literal({integer,I}) when is_integer(I) -> true;
+is_literal({literal,_L}) -> true;
+is_literal(_) -> false.
%% The possible types.
%%
@@ -2128,6 +2155,7 @@ assert_tuple_elements(Limit, Es) ->
%% Subtract Type2 from Type2. Example:
%% subtract(list, nil) -> cons
+subtract(Same, Same) -> none;
subtract(list, nil) -> cons;
subtract(list, cons) -> nil;
subtract(number, {integer,[]}) -> {float,[]};
diff --git a/lib/compiler/test/beam_validator_SUITE_data/receive_stacked.S b/lib/compiler/test/beam_validator_SUITE_data/receive_stacked.S
index 5b974119c6..a878204d16 100644
--- a/lib/compiler/test/beam_validator_SUITE_data/receive_stacked.S
+++ b/lib/compiler/test/beam_validator_SUITE_data/receive_stacked.S
@@ -240,7 +240,7 @@
{y,0}}.
{'%',{no_bin_opt,{binary_used_in,{test,is_binary,{f,34},[{y,0}]}},
[63,{file,"receive_stacked.erl"}]}}.
- {test,is_binary,{f,34},[{y,0}]}.
+ {test,is_eq_exact,{f,34},[{y,0},{literal,<<0,1,2,3>>}]}.
remove_message.
{move,{integer,42},{x,0}}.
{line,[{location,"receive_stacked.erl",64}]}.
@@ -283,7 +283,7 @@
{y,0}}.
{'%',{no_bin_opt,{[{x,1},{y,0}],{loop_rec_end,{f,38}},not_handled},
[70,{file,"receive_stacked.erl"}]}}.
- {test,is_binary,{f,39},[{x,0}]}.
+ {test,is_eq_exact,{f,39},[{x,0},{literal,<<0,1,2,3>>}]}.
remove_message.
{move,{integer,42},{x,0}}.
{line,[{location,"receive_stacked.erl",71}]}.
generated by cgit v1.2.3 (git 2.25.1) at 2024-08-30 05:27:30 +0000