fix validator

Author: lucioleKi

lib/compiler/src/beam_validator.erl

@@ -2292,12 +2292,15 @@ infer_types_1(#value{op={bif,is_integer},args=[Src,
                                                {integer, Min},
                                                {integer, Max}]}, Val, Op, Vst) ->
     infer_type_test_bif(beam_types:make_integer(Min, Max), Src, Val, Op, Vst);
-infer_types_1(#value{op={bif,is_integer},args=[Src, _, _]}, Val, Op, Vst) ->
-    %% Unknown bounds; we know it's an integer when 'true', but cannot draw
-    %% any conclusions when 'false'.
+infer_types_1(#value{op={bif,is_integer},args=[Src,Min0,Max0]}, Val, Op, Vst) ->
+    %% If there is at least one unknown bound, we cannot subtract
+    %% when 'false'.
+    {Min,_} = infer_integer_get_range(Min0, Vst),
+    {_,Max} = infer_integer_get_range(Max0, Vst),
+    Type = make_integer({Min, Max}),
     case Val of
         {atom, Bool} when Op =:= eq_exact, Bool; Op =:= ne_exact, not Bool ->
-            update_type(fun meet/2, #t_integer{}, Src, Vst);
+            update_type(fun meet/2, Type, Src, Vst);
         _ ->
             Vst
     end;
@@ -2367,6 +2370,25 @@ invert_relop('=<') -> '>';
 invert_relop('>=') -> '<';
 invert_relop('>') -> '=<'.
 
+infer_integer_get_range(Arg, Vst) ->
+    case get_term_type(Arg, Vst) of
+        #t_integer{elements={_,_}=R} ->
+            R;
+        #t_number{elements={Min,Max}=R}
+          when is_integer(Min), is_integer(Max) -> R;
+        _ ->
+            {'-inf','+inf'}
+    end.
+
+make_integer({'-inf','+inf'}) ->
+    #t_integer{};
+make_integer({'-inf',_}=R) ->
+    #t_integer{elements=R};
+make_integer({Min,Max}=R) when is_integer(Min), Min =< Max ->
+    #t_integer{elements=R};
+make_integer(_) ->
+    #t_integer{}.
+
 %%%
 %%% Keeping track of types.
 %%%

lib/compiler/test/guard_SUITE.erl

@@ -3440,11 +3440,11 @@ is_integer_3_guard(_Config) ->
     false = is_integer_3_guard_3(id(1024)),
     true = is_integer_3_guard_3(id(1025)),
 
-    true = is_integer_3_guard_4(id(2), id(5)),
-    false = is_integer_3_guard_4(id(2), id(0)),
-    false = is_integer_3_guard_4(id(5), id(3)),
-    false = is_integer_3_guard_4(id(1024), id(1023)),
-    true = is_integer_3_guard_4(id(1025), id(1026)),
+    1 = is_integer_3_guard_4(id(1), id(0), id(5)),
+    false = is_integer_3_guard_4(id(1), id(-1), id(0)),
+
+    2 = is_integer_3_guard_5(id(2), id(0), id(9)),
+    false = is_integer_3_guard_5(id(1024), id(0), id(9)),
 
     ok.
 
@@ -3463,11 +3463,18 @@ is_integer_3_guard_3(X) when not is_integer(X, 1, 1024) ->
 is_integer_3_guard_3(X) ->
     not is_integer(X, 1, 1024).
 
-is_integer_3_guard_4(X, Y) when is_integer(X, 1, Y) ->
-    true = is_integer(X, 1, Y);
-is_integer_3_guard_4(X, Y) when is_integer(X, Y, 1)->
-    is_integer(X, Y, 1);
-is_integer_3_guard_4(_, _) -> false.
+is_integer_3_guard_4(X, LB, UB) when 0 =< LB, UB < 10, is_integer(X, LB, UB) ->
+    is_integer_id(X);
+is_integer_3_guard_4(X, LB, UB) ->
+    is_integer(X, LB, UB).
+
+is_integer_3_guard_5(X, LB, UB) when 0 =< LB,  is_integer(UB),
+                                     UB < 10, is_integer(X, LB, UB) ->
+    is_integer_id(X);
+is_integer_3_guard_5(X, LB, UB) ->
+    is_integer(X, LB, UB).
+
+is_integer_id(I) -> I.
 
 %% Call this function to turn off constant propagation.
 id(I) -> I.