[PATCH 1/4] S390: For zero, let is_power_of_two() return false

[Andreas Arnez <arnez@linux.vnet.ibm.com>]

This fixes a minor issue with the helper function is_power_of_two(),
which returned non-zero ("true") if the argument was zero.  This led
to a wrong decision when passing a zero-sized struct in an inferior
function call.

gdb/ChangeLog:

	* s390-linux-tdep.c (is_power_of_two): Add comment.  Return
          false if the argument is zero.
---
 gdb/s390-linux-tdep.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/gdb/s390-linux-tdep.c b/gdb/s390-linux-tdep.c
index b83a264..44feee7 100644
--- a/gdb/s390-linux-tdep.c
+++ b/gdb/s390-linux-tdep.c
@@ -2484,11 +2484,12 @@ is_float_like (struct type *type)
 	  || is_float_singleton (type));
 }
 
+/* Determine whether N is a power of two.  */
 
 static int
 is_power_of_two (unsigned int n)
 {
-  return ((n & (n - 1)) == 0);
+  return n && ((n & (n - 1)) == 0);
 }
 
 /* Return non-zero if TYPE should be passed as a pointer to a copy,
-- 
1.9.3