aboutsummaryrefslogtreecommitdiffstats
path: root/lib/hipe
diff options
context:
space:
mode:
authorStavros Aronis <[email protected]>2011-07-21 00:29:58 +0200
committerStavros Aronis <[email protected]>2011-08-29 09:31:35 +0300
commite7f7a3052096286a3df0b6c2217a9fe3248be7f4 (patch)
treea699147c8e7a6a59225d4cfa4f52de8661ea2d0b /lib/hipe
parent25b2e4850a231ac868c966f8ef3c2fbfe2f7dfde (diff)
downloadotp-e7f7a3052096286a3df0b6c2217a9fe3248be7f4.tar.gz
otp-e7f7a3052096286a3df0b6c2217a9fe3248be7f4.tar.bz2
otp-e7f7a3052096286a3df0b6c2217a9fe3248be7f4.zip
Enhance Dialyzer's inference on comparisons
This patch makes Dialyzer aware of Erlang's total ordering of terms, enabling discrepancy detection in cases where e.g. integer() < tuple() is treated as a comparison that might also return false (when it is certain to always return true).
Diffstat (limited to 'lib/hipe')
-rw-r--r--lib/hipe/cerl/erl_bif_types.erl52
1 files changed, 48 insertions, 4 deletions
diff --git a/lib/hipe/cerl/erl_bif_types.erl b/lib/hipe/cerl/erl_bif_types.erl
index 82e3675938..cd5d23c50c 100644
--- a/lib/hipe/cerl/erl_bif_types.erl
+++ b/lib/hipe/cerl/erl_bif_types.erl
@@ -366,7 +366,7 @@ type(erlang, '>', 2, Xs = [Lhs, Rhs]) ->
is_integer(LhsMax), is_integer(RhsMin), RhsMin >= LhsMax -> F;
true -> t_boolean()
end;
- false -> t_boolean()
+ false -> compare('>', Lhs, Rhs)
end,
strict(Xs, Ans);
type(erlang, '>=', 2, Xs = [Lhs, Rhs]) ->
@@ -384,7 +384,7 @@ type(erlang, '>=', 2, Xs = [Lhs, Rhs]) ->
is_integer(LhsMax), is_integer(RhsMin), RhsMin > LhsMax -> F;
true -> t_boolean()
end;
- false -> t_boolean()
+ false -> compare('>=', Lhs, Rhs)
end,
strict(Xs, Ans);
type(erlang, '<', 2, Xs = [Lhs, Rhs]) ->
@@ -402,7 +402,7 @@ type(erlang, '<', 2, Xs = [Lhs, Rhs]) ->
is_integer(LhsMin), is_integer(RhsMax), RhsMax =< LhsMin -> F;
true -> t_boolean()
end;
- false -> t_boolean()
+ false -> compare('<', Lhs, Rhs)
end,
strict(Xs, Ans);
type(erlang, '=<', 2, Xs = [Lhs, Rhs]) ->
@@ -420,7 +420,7 @@ type(erlang, '=<', 2, Xs = [Lhs, Rhs]) ->
is_integer(LhsMin), is_integer(RhsMax), RhsMax < LhsMin -> F;
true -> t_boolean()
end;
- false -> t_boolean()
+ false -> compare('=<', Lhs, Rhs)
end,
strict(Xs, Ans);
type(erlang, '+', 1, Xs) ->
@@ -3178,6 +3178,50 @@ arith(Op, X1, X2) ->
end.
%%=============================================================================
+%% Comparison of terms
+%%=============================================================================
+
+compare(Op, Lhs, Rhs) ->
+ case t_is_none(t_inf(Lhs, Rhs)) of
+ false -> t_boolean();
+ true ->
+ case Op of
+ '<' -> always_smaller(Lhs, Rhs);
+ '>' -> always_smaller(Rhs, Lhs);
+ '=<' -> always_smaller(Lhs, Rhs);
+ '>=' -> always_smaller(Rhs, Lhs)
+ end
+ end.
+
+always_smaller(Type1, Type2) ->
+ {Min1, Max1} = type_ranks(Type1),
+ {Min2, Max2} = type_ranks(Type2),
+ if Max1 < Min2 -> t_atom('true');
+ Min1 > Max2 -> t_atom('false');
+ true -> t_boolean()
+ end.
+
+type_ranks(Type) ->
+ type_ranks(Type, 1, 0, 0, type_order()).
+
+type_ranks(_Type, _I, Min, Max, []) -> {Min, Max};
+type_ranks(Type, I, Min, Max, [TypeClass|Rest]) ->
+ {NewMin, NewMax} =
+ case t_is_none(t_inf(Type, TypeClass)) of
+ true -> {Min, Max};
+ false -> case Min of
+ 0 -> {I, I};
+ _ -> {Min, I}
+ end
+ end,
+ type_ranks(Type, I+1, NewMin, NewMax, Rest).
+
+type_order() ->
+ [t_number(), t_atom(), t_reference(), t_fun(), t_port(), t_pid(), t_tuple(),
+ t_list(), t_binary()].
+
+
+%%=============================================================================
-spec arg_types(atom(), atom(), arity()) -> [erl_types:erl_type()] | 'unknown'.