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[m68k] return values
- From: Nathan Sidwell <nathan at codesourcery dot com>
- To: gdb-patches at sourceware dot org
- Cc: Andreas Schwab <schwab at suse dot de>
- Date: Fri, 09 Jun 2006 14:05:23 +0100
- Subject: [m68k] return values
this is a reworking of my recent return value patch. this patch just contains
changes to select which register contains a pointer value, and how structure
return values are located.
I've added tdep field 'ptr_value_regnum' to accommodate the different ABIs that
return in %d0 or %a0.
Most of the patch is adding the necessary pieces to the os sniffers to
initialize that value.
ok?
nathan
--
Nathan Sidwell :: http://www.codesourcery.com :: CodeSourcery
nathan@codesourcery.com :: http://www.planetfall.pwp.blueyonder.co.uk
2006-06-09 Nathan Sidwell <nathan@codesourcery.com>
* configure.tgt (gdb_osabi): uclinux is like linux.
* m68k-tdep.c (m68k_svr4_extract_return_value): Use
tdep->ptr_value_regnum for pointer returns.
(m68k_svr4_store_return_value): Likewise.
(m68k_svr4_init_abi, m68k_aout_init_abi): Set ptr_value_regnum.
(m68k_gdbarch_init): Likewise.
* m68k-tdep.h (struct gdbarch_tdep): Add ptr_value_regnum
field.
* m68kbsd-tdep.c (m68kbsd_aout_init_abi): Use m68k_aout_init_abi.
(m68kbsd_elf_init_abi): Add comment.
* m68klinux-tdep.c (m68k_linux_init_abi): Just set the struct
pointer register here.
Index: configure.tgt
===================================================================
RCS file: /cvs/src/src/gdb/configure.tgt,v
retrieving revision 1.172
diff -c -3 -p -r1.172 configure.tgt
*** configure.tgt 20 Apr 2006 23:18:48 -0000 1.172
--- configure.tgt 9 Jun 2006 12:45:08 -0000
*************** esac
*** 223,228 ****
--- 223,229 ----
case "${target}" in
*-*-freebsd*) gdb_osabi=GDB_OSABI_FREEBSD_ELF ;;
*-*-linux*) gdb_osabi=GDB_OSABI_LINUX ;;
+ *-*-uclinux*) gdb_osabi=GDB_OSABI_LINUX ;;
*-*-nto*) gdb_osabi=GDB_OSABI_QNXNTO ;;
m68*-*-openbsd* | m88*-*-openbsd* | vax-*-openbsd*) ;;
*-*-openbsd*) gdb_osabi=GDB_OSABI_OPENBSD_ELF ;;
Index: m68k-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/m68k-tdep.c,v
retrieving revision 1.106
diff -c -3 -p -r1.106 m68k-tdep.c
*** m68k-tdep.c 8 Jun 2006 19:11:45 -0000 1.106
--- m68k-tdep.c 9 Jun 2006 12:45:09 -0000
*************** m68k_svr4_extract_return_value (struct t
*** 253,259 ****
convert_typed_floating (buf, builtin_type_m68881_ext, valbuf, type);
}
else if (TYPE_CODE (type) == TYPE_CODE_PTR && len == 4)
! regcache_raw_read (regcache, M68K_A0_REGNUM, valbuf);
else
m68k_extract_return_value (type, regcache, valbuf);
}
--- 253,261 ----
convert_typed_floating (buf, builtin_type_m68881_ext, valbuf, type);
}
else if (TYPE_CODE (type) == TYPE_CODE_PTR && len == 4)
! regcache_raw_read (regcache,
! gdbarch_tdep (current_gdbarch)->ptr_value_regnum,
! valbuf);
else
m68k_extract_return_value (type, regcache, valbuf);
}
*************** m68k_svr4_store_return_value (struct typ
*** 292,301 ****
regcache_raw_write (regcache, M68K_FP0_REGNUM, buf);
}
else if (TYPE_CODE (type) == TYPE_CODE_PTR && len == 4)
! {
! regcache_raw_write (regcache, M68K_A0_REGNUM, valbuf);
! regcache_raw_write (regcache, M68K_D0_REGNUM, valbuf);
! }
else
m68k_store_return_value (type, regcache, valbuf);
}
--- 294,302 ----
regcache_raw_write (regcache, M68K_FP0_REGNUM, buf);
}
else if (TYPE_CODE (type) == TYPE_CODE_PTR && len == 4)
! regcache_raw_write (regcache,
! gdbarch_tdep (current_gdbarch)->ptr_value_regnum,
! valbuf);
else
m68k_store_return_value (type, regcache, valbuf);
}
*************** m68k_svr4_return_value (struct gdbarch *
*** 370,394 ****
if ((code == TYPE_CODE_STRUCT || code == TYPE_CODE_UNION)
&& !m68k_reg_struct_return_p (gdbarch, type))
{
! /* The System V ABI says that:
!
! "A function returning a structure or union also sets %a0 to
! the value it finds in %a0. Thus when the caller receives
! control again, the address of the returned object resides in
! register %a0."
!
! So the ABI guarantees that we can always find the return
! value just after the function has returned. */
!
! if (readbuf)
! {
! ULONGEST addr;
!
! regcache_raw_read_unsigned (regcache, M68K_A0_REGNUM, &addr);
! read_memory (addr, readbuf, TYPE_LENGTH (type));
! }
!
! return RETURN_VALUE_ABI_RETURNS_ADDRESS;
}
/* This special case is for structures consisting of a single
--- 371,381 ----
if ((code == TYPE_CODE_STRUCT || code == TYPE_CODE_UNION)
&& !m68k_reg_struct_return_p (gdbarch, type))
{
! /* Although they SYSV ABI specifies that a function returning a
! structure this way should preserve %a0, GCC doesn't do that.
! Furthermore there's no point changeing GCC to make it do it,
! as that would just be bloat. */
! return RETURN_VALUE_STRUCT_CONVENTION;
}
/* This special case is for structures consisting of a single
*************** m68k_svr4_init_abi (struct gdbarch_info
*** 1124,1131 ****
/* SVR4 uses a different calling convention. */
set_gdbarch_return_value (gdbarch, m68k_svr4_return_value);
! /* SVR4 uses %a0 instead of %a1. */
tdep->struct_value_regnum = M68K_A0_REGNUM;
}
--- 1111,1137 ----
/* SVR4 uses a different calling convention. */
set_gdbarch_return_value (gdbarch, m68k_svr4_return_value);
! /* SVR4 uses %a0. */
tdep->struct_value_regnum = M68K_A0_REGNUM;
+ tdep->struct_return = reg_struct_return;
+ /* Pointers are returned in %a0 */
+ tdep->ptr_value_regnum = M68K_A0_REGNUM;
+ }
+
+ /* a.out */
+
+ void
+ m68k_aout_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
+ {
+ struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
+ set_gdbarch_return_value (gdbarch, m68k_return_value);
+
+ /* aout uses %a1 */
+ tdep->struct_value_regnum = M68K_A1_REGNUM;
+ tdep->struct_return = reg_struct_return;
+ /* Pointers are returned in %a0 */
+ tdep->ptr_value_regnum = M68K_A0_REGNUM;
}
*************** m68k_gdbarch_init (struct gdbarch_info i
*** 1175,1182 ****
set_gdbarch_register_to_value (gdbarch, m68k_register_to_value);
set_gdbarch_value_to_register (gdbarch, m68k_value_to_register);
set_gdbarch_push_dummy_call (gdbarch, m68k_push_dummy_call);
! set_gdbarch_return_value (gdbarch, m68k_return_value);
/* Disassembler. */
set_gdbarch_print_insn (gdbarch, print_insn_m68k);
--- 1181,1194 ----
set_gdbarch_register_to_value (gdbarch, m68k_register_to_value);
set_gdbarch_value_to_register (gdbarch, m68k_value_to_register);
+ /* Function call & return */
set_gdbarch_push_dummy_call (gdbarch, m68k_push_dummy_call);
! /* These values are for bare metal -- os specific ABIs can override
! them */
! set_gdbarch_return_value (gdbarch, m68k_svr4_return_value);
! tdep->struct_value_regnum = M68K_A0_REGNUM;
! tdep->struct_return = reg_struct_return;
! tdep->ptr_value_regnum = M68K_D0_REGNUM;
/* Disassembler. */
set_gdbarch_print_insn (gdbarch, print_insn_m68k);
*************** m68k_gdbarch_init (struct gdbarch_info i
*** 1187,1194 ****
#else
tdep->jb_pc = -1;
#endif
- tdep->struct_value_regnum = M68K_A1_REGNUM;
- tdep->struct_return = reg_struct_return;
/* Frame unwinder. */
set_gdbarch_unwind_dummy_id (gdbarch, m68k_unwind_dummy_id);
--- 1199,1204 ----
Index: m68k-tdep.h
===================================================================
RCS file: /cvs/src/src/gdb/m68k-tdep.h,v
retrieving revision 1.10
diff -c -3 -p -r1.10 m68k-tdep.h
*** m68k-tdep.h 17 Dec 2005 22:34:01 -0000 1.10
--- m68k-tdep.h 9 Jun 2006 12:45:09 -0000
*************** struct gdbarch_tdep
*** 76,85 ****
--- 76,90 ----
/* Convention for returning structures. */
enum struct_return struct_return;
+
+ /* Register in which pointers are returned. */
+ int ptr_value_regnum;
};
/* Initialize a SVR4 architecture variant. */
extern void m68k_svr4_init_abi (struct gdbarch_info, struct gdbarch *);
+ /* Initialize a aout architecture variant. */
+ extern void m68k_aout_init_abi (struct gdbarch_info, struct gdbarch *);
/* Functions exported from m68kbsd-tdep.c. */
Index: m68kbsd-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/m68kbsd-tdep.c,v
retrieving revision 1.7
diff -c -3 -p -r1.7 m68kbsd-tdep.c
*** m68kbsd-tdep.c 17 Dec 2005 22:34:01 -0000 1.7
--- m68kbsd-tdep.c 9 Jun 2006 12:45:09 -0000
*************** m68kbsd_aout_init_abi (struct gdbarch_in
*** 206,212 ****
m68kbsd_init_abi (info, gdbarch);
! tdep->struct_return = reg_struct_return;
tramp_frame_prepend_unwinder (gdbarch, &m68kobsd_sigtramp);
}
--- 206,212 ----
m68kbsd_init_abi (info, gdbarch);
! m68k_aout_init_abi (info, gdbarch);
tramp_frame_prepend_unwinder (gdbarch, &m68kobsd_sigtramp);
}
*************** m68kbsd_elf_init_abi (struct gdbarch_inf
*** 222,227 ****
--- 222,228 ----
/* NetBSD ELF uses the SVR4 ABI. */
m68k_svr4_init_abi (info, gdbarch);
+ /* But with pcc structure return */
tdep->struct_return = pcc_struct_return;
/* NetBSD ELF uses SVR4-style shared libraries. */
Index: m68klinux-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/m68klinux-tdep.c,v
retrieving revision 1.18
diff -c -3 -p -r1.18 m68klinux-tdep.c
*** m68klinux-tdep.c 20 Apr 2006 17:29:47 -0000 1.18
--- m68klinux-tdep.c 9 Jun 2006 12:45:09 -0000
*************** m68k_linux_init_abi (struct gdbarch_info
*** 291,298 ****
address to store a structure value. It also returns small
structures in registers instead of memory. */
m68k_svr4_init_abi (info, gdbarch);
tdep->struct_value_regnum = M68K_A1_REGNUM;
- tdep->struct_return = reg_struct_return;
frame_unwind_append_sniffer (gdbarch, m68k_linux_sigtramp_frame_sniffer);
--- 291,298 ----
address to store a structure value. It also returns small
structures in registers instead of memory. */
m68k_svr4_init_abi (info, gdbarch);
+ /* But the struct pointer is in %a1 */
tdep->struct_value_regnum = M68K_A1_REGNUM;
frame_unwind_append_sniffer (gdbarch, m68k_linux_sigtramp_frame_sniffer);