improve type inference when one of the bounds is a literal

Author: lucioleKi

lib/compiler/src/beam_ssa_type.erl

@@ -2819,6 +2819,14 @@ infer_type({bif,is_integer}, [#b_var{}=Arg,
                               #b_literal{val=Max}], _Ts, _Ds) when Min =< Max ->
     T = {Arg, beam_types:make_integer(Min, Max)},
     {[T], [T]};
+infer_type({bif,is_integer}, [#b_var{}=Arg,
+                              #b_literal{val=Min},_], _Ts, _Ds) ->
+    T = {Arg, make_number({Min,'+inf'})},
+    {[T], [T]};
+infer_type({bif,is_integer}, [#b_var{}=Arg,_,
+                              #b_literal{val=Max}], _Ts, _Ds) ->
+    T = {Arg, make_number({'-inf',Max})},
+    {[T], [T]};
 infer_type({bif,is_integer}, [#b_var{}=Arg, _, _], _Ts, _Ds) ->
     %% We cannot subtract the type when the bounds are unknown: `Arg` may still
     %% be an integer if it is not in the tested range.

lib/compiler/test/guard_SUITE.erl

@@ -3440,6 +3440,12 @@ 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)),
+
     ok.
 
 is_integer_3_guard_1(X, LB, UB) when is_integer(X, LB, UB) ->
@@ -3457,6 +3463,12 @@ 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.
+
 %% Call this function to turn off constant propagation.
 id(I) -> I.