bitwise: accept all ones as non-restricted value

Currently, the only value bitwise types can act on is 0
because the this value is anyway invariant for all bitwise
operations and endianness conversions.

But, a bit-pattern of all ones has the same properties and
is also very often used.

So, accept all ones as a valid value for bitwise operations.

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>

2 files changed, 14 insertions, 1 deletions

diff --git a/evaluate.c b/evaluate.c
index 61f59ee3..bcbcdf1e 100644
--- a/evaluate.c
+++ b/evaluate.c
@@ -417,7 +417,7 @@ static int restricted_value(struct expression *v, struct symbol *type)
 {
 	if (v->type != EXPR_VALUE)
 		return 1;
-	if (v->value != 0)
+	if (v->value != 0 && v->value != bits_mask(type->bit_size))
 		return 1;
 	return 0;
 }
diff --git a/validation/bitwise-cast.c b/validation/bitwise-cast.c
index 0583461c..1075a3e9 100644
--- a/validation/bitwise-cast.c
+++ b/validation/bitwise-cast.c
@@ -35,6 +35,19 @@ static __be32 quuy(void)
 	return (__attribute__((force)) __be32) 1730;
 }
 
+/* Implicit casts of all ones, legal */
+static __be32 foo1(void)
+{
+	__be32 x = 0xffffffff;
+	return x;
+}
+
+/* Explicit cast of all ones, legal */
+static __be32 bar1(void)
+{
+	return (__be32)0xffffffff;
+}
+
 /*
  * check-name: conversions to bitwise types
  * check-command: sparse -Wbitwise $file