s390: Fix infcalls passing a single-field struct with static members
Commit Message
The infcall-nested-structs test case yields 36 FAILs on s390x because GCC
and GDB disagree on how to pass a C++ struct like this as an argument to a
function:
struct s { float x; static float y; };
For the purpose of argument passing, GCC ignores static fields, while GDB
does not. Thus GCC passes the argument in a floating-point register and
GDB passes it via memory.
Fix this by explicitly ignoring static fields when detecting single-field
structs.
gdb/ChangeLog:
* s390-tdep.c (s390_effective_inner_type): Ignore static fields
when unwrapping single-field structs.
---
gdb/s390-tdep.c | 21 ++++++++++++++++++---
1 file changed, 18 insertions(+), 3 deletions(-)
Comments
>>>>> "Andreas" == Andreas Arnez <arnez@linux.ibm.com> writes:
Andreas> The infcall-nested-structs test case yields 36 FAILs on s390x because GCC
Andreas> and GDB disagree on how to pass a C++ struct like this as an argument to a
Andreas> function:
Andreas> struct s { float x; static float y; };
Andreas> For the purpose of argument passing, GCC ignores static fields, while GDB
Andreas> does not. Thus GCC passes the argument in a floating-point register and
Andreas> GDB passes it via memory.
Andreas> Fix this by explicitly ignoring static fields when detecting single-field
Andreas> structs.
FWIW this looked reasonable to me.
Tom
On Fri, Oct 11 2019, Tom Tromey wrote:
>>>>>> "Andreas" == Andreas Arnez <arnez@linux.ibm.com> writes:
>
> Andreas> The infcall-nested-structs test case yields 36 FAILs on s390x because GCC
> Andreas> and GDB disagree on how to pass a C++ struct like this as an argument to a
> Andreas> function:
>
> Andreas> struct s { float x; static float y; };
>
> Andreas> For the purpose of argument passing, GCC ignores static fields, while GDB
> Andreas> does not. Thus GCC passes the argument in a floating-point register and
> Andreas> GDB passes it via memory.
>
> Andreas> Fix this by explicitly ignoring static fields when detecting single-field
> Andreas> structs.
>
> FWIW this looked reasonable to me.
Thanks for having a look at this!
Pushed as ba18312d8f2cecf88b6edcbc277f433a62131e58.
--
Andreas
@@ -1637,11 +1637,26 @@ s390_address_class_name_to_type_flags (struct gdbarch *gdbarch,
static struct type *
s390_effective_inner_type (struct type *type, unsigned int min_size)
{
- while (TYPE_CODE (type) == TYPE_CODE_STRUCT
- && TYPE_NFIELDS (type) == 1)
+ while (TYPE_CODE (type) == TYPE_CODE_STRUCT)
{
- struct type *inner = check_typedef (TYPE_FIELD_TYPE (type, 0));
+ struct type *inner = NULL;
+ /* Find a non-static field, if any. Unless there's exactly one,
+ abort the unwrapping. */
+ for (int i = 0; i < TYPE_NFIELDS (type); i++)
+ {
+ struct field f = TYPE_FIELD (type, i);
+
+ if (field_is_static (&f))
+ continue;
+ if (inner != NULL)
+ return type;
+ inner = FIELD_TYPE (f);
+ }
+
+ if (inner == NULL)
+ break;
+ inner = check_typedef (inner);
if (TYPE_LENGTH (inner) < min_size)
break;
type = inner;