[PATCH/RFA] Fix returning small structs on OpenBSD/arm

Mark Kettenis
2006-07-19T21:26:35Z

On OpenBSD/arm, all structures are returned in memory, i.e. the
-fpcc-struct-return GCC option is the default. There are a couple of
different ways we deal with pcc/reg struct return in GDB. This adapts
the way things are done on i386 and m68k. This makes it easy to
provide a user command to switch from one convention to the other like
i386 already has. However, right now I don't actually see much reason
to add that option on arm.

Anyway, this shaves another 80 failures from the testsuite on
OpenBSD/arm.

ok?

Index: ChangeLog
===================================================================
RCS file: /cvs/src/src/gdb/ChangeLog,v
retrieving revision 1.7834
diff -u -p -r1.7834 ChangeLog
--- ChangeLog 19 Jul 2006 18:21:36 -0000 1.7834
+++ ChangeLog 19 Jul 2006 21:20:39 -0000
@@ -1,5 +1,15 @@
2006-07-19 Mark Kettenis <kettenis@gnu.org>

+ * arm-tdep.h (enum struct_return): New.
+ (struct gdbarch_tdep): Add struct_return member.
+ * arm-tdep.c (arm_return_value): Return
+ RETURN_VALUE_STRUCT_CONVENTION for aggregates when the ABI uses
+ pcc_struct_return.
+ (arm_gdbarch_init): Default to reg_struct_return.
+ * armobsd-tdep.c (armobsd_init_abi): Set pcc_struct_return.
+
+2006-07-19 Mark Kettenis <kettenis@gnu.org>
+
* arm-tdep.c (arm_gdbarch_init): Get default floating-point model
from ELF flags for binaries produced by the GNU toolchain.

Index: arm-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/arm-tdep.c,v
retrieving revision 1.212
diff -u -p -r1.212 arm-tdep.c
--- arm-tdep.c 19 Jul 2006 18:21:36 -0000 1.212
+++ arm-tdep.c 19 Jul 2006 21:20:41 -0000
@@ -2259,11 +2259,14 @@ arm_return_value (struct gdbarch *gdbarc
struct regcache *regcache, gdb_byte *readbuf,
const gdb_byte *writebuf)
{
+ struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
if (TYPE_CODE (valtype) == TYPE_CODE_STRUCT
|| TYPE_CODE (valtype) == TYPE_CODE_UNION
|| TYPE_CODE (valtype) == TYPE_CODE_ARRAY)
{
- if (arm_return_in_memory (gdbarch, valtype))
+ if (tdep->struct_return == pcc_struct_return
+ || arm_return_in_memory (gdbarch, valtype))
return RETURN_VALUE_STRUCT_CONVENTION;
}

@@ -2757,6 +2760,10 @@ arm_gdbarch_init (struct gdbarch_info in
tdep->lowest_pc = 0x20;
tdep->jb_pc = -1; /* Longjump support not enabled by default. */

+ /* The default, for both APCS and AAPCS, is to return small
+ structures in registers. */
+ tdep->struct_return = reg_struct_return;
+
set_gdbarch_push_dummy_call (gdbarch, arm_push_dummy_call);
set_gdbarch_frame_align (gdbarch, arm_frame_align);

Index: arm-tdep.h
===================================================================
RCS file: /cvs/src/src/gdb/arm-tdep.h,v
retrieving revision 1.15
diff -u -p -r1.15 arm-tdep.h
--- arm-tdep.h 12 Jul 2006 20:46:32 -0000 1.15
+++ arm-tdep.h 19 Jul 2006 21:20:41 -0000
@@ -125,6 +125,14 @@ enum arm_abi_kind
ARM_ABI_LAST
};

+/* Convention for returning structures. */
+
+enum struct_return
+{
+ pcc_struct_return, /* Return "short" structures in memory. */
+ reg_struct_return /* Return "short" structures in registers. */
+};
+
/* Target-dependent structure in gdbarch. */
struct gdbarch_tdep
{
@@ -147,10 +155,15 @@ struct gdbarch_tdep
will be disabled. */
size_t jb_elt_size; /* And the size of each entry in the buf. */

+ /* Convention for returning structures. */
+ enum struct_return struct_return;
+
/* Cached core file helpers. */
struct regset *gregset, *fpregset;
};

+
+
#ifndef LOWEST_PC
#define LOWEST_PC (gdbarch_tdep (current_gdbarch)->lowest_pc)
#endif
Index: armobsd-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/armobsd-tdep.c,v
retrieving revision 1.3
diff -u -p -r1.3 armobsd-tdep.c
--- armobsd-tdep.c 18 Jul 2006 21:10:28 -0000 1.3
+++ armobsd-tdep.c 19 Jul 2006 21:20:41 -0000
@@ -88,6 +88,9 @@ armobsd_init_abi (struct gdbarch_info in

tdep->jb_pc = 24;
tdep->jb_elt_size = 4;
+
+ /* OpenBSD/arm uses -fpcc-struct-return by default. */
+ tdep->struct_return = pcc_struct_return;
}

void