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Re: [RFA 5/8] New port: TI C6x: gdb port


On 08/08/2011 09:03 PM, Pedro Alves wrote:
> On Saturday 06 August 2011 03:26:20, Yao Qi wrote:
>> On 08/04/2011 08:33 PM, Pedro Alves wrote:

>>>> +tic6x_arg_type_alignment (struct type *type)
>>>> +{
>>>> +  int len = TYPE_LENGTH (type);
>>>> +  enum type_code typecode = TYPE_CODE (type);
>>>
>>> I think a check_typedef is in order.
>>>
>>>
>>
>> This line is changed to:
>>
>>   enum type_code typecode = TYPE_CODE (check_typedef (type));
> 
> You should call check_typedef earlier, before TYPE_LENGTH, not just
> before TYPE_CODE.
> 

OK, call check_typedef before both TYPE_LENGTH and TYPE_CODE.

>> +
>> +/* Macros */
>> +
>> +#define TIC6X_OPCODE_SIZE 4
>> +#define TIC6X_FETCH_PACKET_SIZE 32
>> +
>> +static int arg_regs[] = { 4, 20, 6, 22, 8, 24, 10, 26, 12, 28 };
> 
> const?  Can you add a comment meantioning what this is?

Added, and moved it out of "macro" section.

> It's not a "macro", so I'd say the "Macros" and "Structures" comments are
> bound for bit rot.
> 
>> +/* Structures */
>> +struct register_info
>> +{
>> +  int size;
>> +  char *name;
>> +};
> 
> Same.
> 

Remove "struct register_info" since size field is not used anymore.

>> +/* tic6x_register_info_table[i] is the number of bytes of storage in
>> +   GDB's register array occupied by register i.  */
>> +static struct register_info tic6x_register_info_table[] =
>> +{
>> +  /*   0 */ {4, "A0"},
>> +  /*   1 */ {4, "A1"},
>> +  /*   2 */ {4, "A2"},
>> +  /*   3 */ {4, "A3"},
>> +  /*   4 */ {4, "A4"},
>> +  /*   5 */ {4, "A5"},
>> +  /*   6 */ {4, "A6"},
>> +  /*   7 */ {4, "A7"},
>> +  /*   8 */ {4, "A8"},
>> +  /*   9 */ {4, "A9"},
>> +  /*  10 */ {4, "A10"},
>> +  /*  11 */ {4, "A11"},
>> +  /*  12 */ {4, "A12"},
>> +  /*  13 */ {4, "A13"},
>> +  /*  14 */ {4, "A14"},
>> +  /*  15 */ {4, "A15"},
>> +  /*  16 */ {4, "B0"},
>> +  /*  17 */ {4, "B1"},
>> +  /*  18 */ {4, "B2"},
>> +  /*  19 */ {4, "B3"},
>> +  /*  20 */ {4, "B4"},
>> +  /*  21 */ {4, "B5"},
>> +  /*  22 */ {4, "B6"},
>> +  /*  23 */ {4, "B7"},
>> +  /*  24 */ {4, "B8"},
>> +  /*  25 */ {4, "B9"},
>> +  /*  26 */ {4, "B10"},
>> +  /*  27 */ {4, "B11"},
>> +  /*  28 */ {4, "B12"},
>> +  /*  29 */ {4, "B13"},
>> +  /*  30 */ {4, "B14"},
>> +  /*  31 */ {4, "B15"},
>> +  /*  32 */ {4, "CSR"},
>> +  /*  33 */ {4, "PC"},
>> +};
> 
> (I do wonder why do you need the register size field, if you're
> always going to put '4' there anyway.)
> 

Yeah, agree.  Change tic6x_register_info_table to tic6x_register_names,
an array of char*.

>> +
>> +/* This is the implementation of gdbarch method register_name.  */
>> +
>> +static const char *
>> +tic6x_register_name (struct gdbarch *gdbarch, int regno)
>> +{
>> +  if (regno < 0)
>> +    return NULL;
>> +
>> +  if (tdesc_has_registers (gdbarch_target_desc (gdbarch)))
>> +    return tdesc_register_name (gdbarch, regno);
>> +  else if (regno >=  ARRAY_SIZE (tic6x_register_info_table))
> 
> Spurious double space.
> 

Fixed.

>> +    return "";
>> +  else
>> +    return tic6x_register_info_table[regno].name;
>> +}
>> +
>> +/* This is the implementation of gdbarch method register_type.  */
>> +
>> +static struct type *
>> +tic6x_register_type (struct gdbarch *gdbarch, int regno)
>> +{
>> +
>> +  if (regno ==  TIC6X_PC_REGNUM)
> 
> Spurious double space.
> 

Fixed.

>> +    return builtin_type (gdbarch)->builtin_func_ptr;
>> +  else
>> +    return builtin_type (gdbarch)->builtin_uint32;
>> +}
> 
>> +/* Our frame ID for a stub frame is the current SP and LR.  */
> 
> Is this comment right?
> 

Hmm, the comment is out of date.  Get rid of it.

>> +
>> +static void
>> +tic6x_stub_this_id (struct frame_info *this_frame, void **this_cache,
>> +                   struct frame_id *this_id)
>> +{
>> +  struct tic6x_unwind_cache *cache;
>> +
>> +  if (*this_cache == NULL)
>> +    *this_cache = tic6x_make_stub_cache (this_frame);
>> +  cache = *this_cache;
>> +
>> +  *this_id = frame_id_build (cache->cfa, get_frame_pc (this_frame));
>> +}
>> +
> 
>> +/* Get the register number by decoding raw bits REG, SIDE, and CORSSPATH in
>> +   instruction.  */
> 
> Typo CORSSPATH.
> 

Fixed.

>> +/* This is the implementation of gdbarch method frame_align.  */
>> +
>> +static CORE_ADDR
>> +tic6x_frame_align (struct gdbarch *gdbarch, CORE_ADDR addr)
>> +{
>> +  return align_down (addr, 8);
>> +}
>> +
>> +/* This is the implementation of gdbarch method  register_to_value.  */
> 
> Spurious double space.
> 

Fixed.

>> +
>> +static int
>> +tic6x_register_to_value (struct frame_info *frame, int regnum,
>> +                        struct type *type, gdb_byte * to,
>> +                        int *optimizedp, int *unavailablep)
>> +{
>> +  get_frame_register (frame, regnum, (char *) to);
>> +  *optimizedp = *unavailablep = 0;
>> +  return 1;
>> +}
>> +
>> +/* This is the implementation of gdbarch method value_to_register.  */
>> +
>> +static void
>> +tic6x_value_to_register (struct frame_info *frame, int regnum,
>> +                        struct type *type, const gdb_byte *from)
>> +{
>> +  put_frame_register (frame, regnum, (const char *) from);
>> +}
> 
> Please remove the casts as well.
> 

Removed.

>> +  /* Hook in ABI-specific overrides, if they have been registered.  */
>> +  gdbarch_init_osabi (info, gdbarch);
>> +
>> +  if (tdesc_data)
>> +    {
>> +      tdesc_use_registers (gdbarch, tdesc, tdesc_data);
>> +    }
> 
> Unnecessary braces.
> 
> 

Removed.

>> +
>> +  return gdbarch;
>> +}
>> +
>> +void
>> +_initialize_tic6x_tdep (void)
>> +{
>> +  register_gdbarch_init (bfd_arch_tic6x, tic6x_gdbarch_init);
>> +}
> 
> No target descriptions initialized for tic6x-*-* ?
> 

Yes, we have target descriptions for tic6x-uclinux, but don't have for
tic6x-elf so far.  So the target description is initialized in
tic6x-linux-tdep.c:_initialize_tic6x_linux_tdep.

I think the target description initialization should be moved to
tic6x-tdep.c:_initialize_tic6x_tdep, so tic6x-uclinux and tic6x-elf
share the target descriptions.  In my new patch, target description
initialization is moved to tic6x-tdep.c:_initialize_tic6x_tdep, and
suffix "-linux" in feature names and files is removed (target
description is revised accordingly).

-- 
Yao (éå)
2011-08-06  Andrew Jenner  <andrew@codesourcery.com>
            Yao Qi  <yao@codesourcery.com>

	gdb/
	* tic6x-linux-tdep.c: New file.
	* tic6x-tdep.c: New file.
	* tic6x-tdep.h: New file.
---
 gdb/tic6x-linux-tdep.c |  219 ++++++++
 gdb/tic6x-tdep.c       | 1386 ++++++++++++++++++++++++++++++++++++++++++++++++
 gdb/tic6x-tdep.h       |   54 ++
 3 files changed, 1659 insertions(+), 0 deletions(-)
 create mode 100644 gdb/tic6x-linux-tdep.c
 create mode 100644 gdb/tic6x-tdep.c
 create mode 100644 gdb/tic6x-tdep.h

diff --git a/gdb/tic6x-linux-tdep.c b/gdb/tic6x-linux-tdep.c
new file mode 100644
index 0000000..496e981
--- /dev/null
+++ b/gdb/tic6x-linux-tdep.c
@@ -0,0 +1,219 @@
+/* GNU/Linux on  TI C6x target support.
+   Copyright (C) 2011
+   Free Software Foundation, Inc.
+   Contributed by Yao Qi <yao@codesourcery.com>
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "defs.h"
+#include "solib.h"
+#include "osabi.h"
+#include "linux-tdep.h"
+#include "tic6x-tdep.h"
+#include "trad-frame.h"
+#include "tramp-frame.h"
+#include "gdb_assert.h"
+#include "elf-bfd.h"
+#include "elf/tic6x.h"
+
+/* The offset from rt_sigframe pointer to SP register.  */
+#define TIC6X_SP_RT_SIGFRAME 8
+/* Size of struct siginfo info.  */
+#define TIC6X_SIGINFO_SIZE 128
+/* Size of type stack_t, which contains three fields of type void*, int, and
+   size_t respectively.  */
+#define TIC6X_STACK_T_SIZE (3 * 4)
+
+const gdb_byte tic6x_bkpt_illegal_opcode_be[] = { 0x56, 0x45, 0x43, 0x14 };
+const gdb_byte tic6x_bkpt_illegal_opcode_le[] = { 0x14, 0x43, 0x45, 0x56 };
+
+static const gdb_byte tic6x_bkpt_bnop_be[] = { 0x00, 0x00, 0xa1, 0x22 };
+static const gdb_byte tic6x_bkpt_bnop_le[] = { 0x22, 0xa1, 0x00, 0x00 };
+
+/* Return the offset of register REGNUM in struct sigcontext.  Return 0 if no
+   such register in sigcontext.  */
+
+static unsigned int
+tic6x_register_sigcontext_offset (unsigned int regnum, struct gdbarch *gdbarch)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
+  if (regnum == TIC6X_A4_REGNUM || regnum == TIC6X_A4_REGNUM + 2
+      || regnum == TIC6X_A4_REGNUM + 4)
+    return 4 * (regnum - TIC6X_A4_REGNUM + 2);	/* A4, A6, A8 */
+  else if (regnum == TIC6X_A5_REGNUM || regnum == TIC6X_A5_REGNUM + 2
+	   || regnum == TIC6X_A5_REGNUM + 4)
+    return 4 * (regnum - TIC6X_A5_REGNUM + 12);	/* A5, A7, A9 */
+  else if (regnum == TIC6X_B4_REGNUM || regnum == TIC6X_B4_REGNUM + 2
+	   || regnum == TIC6X_B4_REGNUM + 4)
+    return 4 * (regnum - TIC6X_B4_REGNUM + 3);	/* B4, B6, B8 */
+  else if (regnum == TIC6X_B5_REGNUM || regnum == TIC6X_B5_REGNUM + 2
+	   || regnum == TIC6X_B5_REGNUM + 4)
+    return 4 * (regnum - TIC6X_B5_REGNUM + 19);	/* B5, B7, B9 */
+  else if (regnum >= 0 && regnum < TIC6X_A4_REGNUM)
+    return 4 * (regnum - 0 + 8);	/* A0 - A3 */
+  else if (regnum >= TIC6X_B0_REGNUM && regnum < TIC6X_B4_REGNUM)
+    return 4 * (regnum - TIC6X_B0_REGNUM + 15);	/* B0 - B3 */
+  else if (regnum >= 34 && regnum < 34 + 32)
+    return 4 * (regnum - 34 + 23);	/* A16 - A31, B16 - B31 */
+  else if (regnum == TIC6X_PC_REGNUM)
+    return 4 * (tdep->has_gp ? 55 : 23);
+  else if (regnum == TIC6X_SP_REGNUM)
+    return 4;
+
+  return 0;
+}
+
+/* Support unwinding frame in signal trampoline.  We don't check sigreturn,
+   since it is not used in kernel.  */
+
+static void
+tic6x_linux_rt_sigreturn_init (const struct tramp_frame *self,
+			       struct frame_info *this_frame,
+			       struct trad_frame_cache *this_cache,
+			       CORE_ADDR func)
+{
+  struct gdbarch *gdbarch = get_frame_arch (this_frame);
+  CORE_ADDR sp = get_frame_register_unsigned (this_frame, TIC6X_SP_REGNUM);
+  /* The base of struct sigcontext is computed by examining the definition of
+     struct rt_sigframe in linux kernel source arch/c6x/kernel/signal.c.  */
+  CORE_ADDR base = (sp + TIC6X_SP_RT_SIGFRAME
+		    /* Pointer type *pinfo and *puc in struct rt_sigframe.  */
+		    + 4 + 4
+		    + TIC6X_SIGINFO_SIZE
+		    + 4 + 4 /* uc_flags and *uc_link in struct ucontext.  */
+		    + TIC6X_STACK_T_SIZE);
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+  unsigned int reg_offset;
+  unsigned int i;
+
+  for (i = 0; i < 10; i++)	/* A0 - A9 */
+    {
+      reg_offset = tic6x_register_sigcontext_offset (i, gdbarch);
+      gdb_assert (reg_offset != 0);
+
+      trad_frame_set_reg_addr (this_cache, i, base + reg_offset);
+    }
+
+  for (i = TIC6X_B0_REGNUM; i < TIC6X_B0_REGNUM + 10; i++)	/* B0 - B9 */
+    {
+      reg_offset = tic6x_register_sigcontext_offset (i, gdbarch);
+      gdb_assert (reg_offset != 0);
+
+      trad_frame_set_reg_addr (this_cache, i, base + reg_offset);
+    }
+
+  if (tdep->has_gp)
+    for (i = 34; i < 34 + 32; i++)	/* A16 - A31, B16 - B31 */
+      {
+	reg_offset = tic6x_register_sigcontext_offset (i, gdbarch);
+	gdb_assert (reg_offset != 0);
+
+	trad_frame_set_reg_addr (this_cache, i, base + reg_offset);
+      }
+
+  trad_frame_set_reg_addr (this_cache, TIC6X_PC_REGNUM,
+			   base + tic6x_register_sigcontext_offset (TIC6X_PC_REGNUM,
+								    gdbarch));
+  trad_frame_set_reg_addr (this_cache, TIC6X_SP_REGNUM,
+			   base + tic6x_register_sigcontext_offset (TIC6X_SP_REGNUM,
+								    gdbarch));
+
+  /* Save a frame ID.  */
+  trad_frame_set_id (this_cache, frame_id_build (sp, func));
+}
+
+static struct tramp_frame tic6x_linux_rt_sigreturn_tramp_frame =
+{
+  SIGTRAMP_FRAME,
+  4,
+  {
+    {0x000045aa, 0x0fffffff},	/* mvk .S2 139,b0 */
+    {0x10000000, -1},		/* swe */
+    {TRAMP_SENTINEL_INSN}
+  },
+  tic6x_linux_rt_sigreturn_init
+};
+
+/* When FRAME is at a syscall instruction, return the PC of the next
+   instruction to be executed.  */
+
+static CORE_ADDR
+tic6x_linux_syscall_next_pc (struct frame_info *frame)
+{
+  ULONGEST syscall_number = get_frame_register_unsigned (frame,
+							 TIC6X_B0_REGNUM);
+  CORE_ADDR pc = get_frame_pc (frame);
+
+  if (syscall_number == 139 /* rt_sigreturn */)
+    return frame_unwind_caller_pc (frame);
+
+  return pc + 4;
+}
+
+
+extern struct target_so_ops dsbt_so_ops;
+static void
+tic6x_uclinux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
+  linux_init_abi (info, gdbarch);
+
+  /* Shared library handling.  */
+  set_solib_ops (gdbarch, &dsbt_so_ops);
+
+  tdep->syscall_next_pc = tic6x_linux_syscall_next_pc;
+
+#ifdef HAVE_ELF
+  /* In tic6x Linux kernel, breakpoint instructions varies on different archs.
+     On C64x+ and C67x+, breakpoint instruction is 0x56454314, which is an
+     illegal opcode.  On other arch, breakpoint instruction is 0x0000a122
+     (BNOP .S2 0,5).  */
+  if (info.abfd)
+    switch (bfd_elf_get_obj_attr_int (info.abfd, OBJ_ATTR_PROC, Tag_ISA))
+      {
+      case C6XABI_Tag_ISA_C64XP:
+      case C6XABI_Tag_ISA_C67XP:
+	if (info.byte_order == BFD_ENDIAN_BIG)
+	  tdep->breakpoint = tic6x_bkpt_illegal_opcode_be;
+	else
+	  tdep->breakpoint = tic6x_bkpt_illegal_opcode_le;
+	break;
+      default:
+	{
+	  if (info.byte_order == BFD_ENDIAN_BIG)
+	    tdep->breakpoint = tic6x_bkpt_bnop_be;
+	  else
+	    tdep->breakpoint = tic6x_bkpt_bnop_le;
+	}
+      }
+#endif
+
+  /* Signal trampoline support.  */
+  tramp_frame_prepend_unwinder (gdbarch,
+				&tic6x_linux_rt_sigreturn_tramp_frame);
+}
+
+/* Provide a prototype to silence -Wmissing-prototypes.  */
+extern initialize_file_ftype _initialize_tic6x_linux_tdep;
+
+void
+_initialize_tic6x_linux_tdep (void)
+{
+  gdbarch_register_osabi (bfd_arch_tic6x, 0, GDB_OSABI_LINUX,
+			  tic6x_uclinux_init_abi);
+}
diff --git a/gdb/tic6x-tdep.c b/gdb/tic6x-tdep.c
new file mode 100644
index 0000000..eedb5e9
--- /dev/null
+++ b/gdb/tic6x-tdep.c
@@ -0,0 +1,1386 @@
+/* Target dependent code for GDB on TI C6x systems.
+
+   Copyright (C) 2010, 2011.
+   Free Software Foundation, Inc.
+   Contributed by Andrew Jenner <andrew@codesourcery.com>
+   Contributed by Yao Qi <yao@codesourcery.com>
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "defs.h"
+#include "frame.h"
+#include "frame-unwind.h"
+#include "frame-base.h"
+#include "trad-frame.h"
+#include "dwarf2-frame.h"
+#include "symtab.h"
+#include "inferior.h"
+#include "gdbtypes.h"
+#include "gdbcore.h"
+#include "gdbcmd.h"
+#include "target.h"
+#include "dis-asm.h"
+#include "regcache.h"
+#include "value.h"
+#include "symfile.h"
+#include "arch-utils.h"
+#include "floatformat.h"
+#include "glibc-tdep.h"
+#include "infcall.h"
+#include "regset.h"
+#include "tramp-frame.h"
+#include "linux-tdep.h"
+#include "solib.h"
+#include "objfiles.h"
+#include "gdb_assert.h"
+#include "osabi.h"
+#include "tic6x-tdep.h"
+#include "language.h"
+#include "target-descriptions.h"
+
+#include "features/tic6x-c64xp.c"
+#include "features/tic6x-c64x.c"
+#include "features/tic6x-c62x.c"
+
+#define TIC6X_OPCODE_SIZE 4
+#define TIC6X_FETCH_PACKET_SIZE 32
+
+#define INST_S_BIT(INST) ((INST >> 1) & 1)
+#define INST_X_BIT(INST) ((INST >> 12) & 1)
+
+struct tic6x_unwind_cache
+{
+  /* The frame's base, optionally used by the high-level debug info.  */
+  CORE_ADDR base;
+
+  /* The previous frame's inner most stack address.  Used as this
+     frame ID's stack_addr.  */
+  CORE_ADDR cfa;
+
+  /* The address of the first instruction in this function */
+  CORE_ADDR pc;
+
+  /* Which register holds the return address for the frame.  */
+  int return_regnum;
+
+  /* The offset of register saved on stack.  If register is not saved, the
+     corresponding element is -1.  */
+  CORE_ADDR reg_saved[TIC6X_NUM_CORE_REGS];
+};
+
+
+/* Name of TI C6x core registers.  */
+static const char *const tic6x_register_names[] =
+{
+  "A0",  "A1",  "A2",  "A3",  /*  0  1  2  3 */
+  "A4",  "A5",  "A6",  "A7",  /*  4  5  6  7 */
+  "A8",  "A9",  "A10", "A11", /*  8  9 10 11 */
+  "A12", "A13", "A14", "A15", /* 12 13 14 15 */
+  "B0",  "B1",  "B2",  "B3",  /* 16 17 18 19 */
+  "B4",  "B5",  "B6",  "B7",  /* 20 21 22 23 */
+  "B8",  "B9",  "B10", "B11", /* 24 25 26 27 */
+  "B12", "B13", "B14", "B15", /* 28 29 30 31 */
+  "CSR", "PC",                /* 32 33       */
+};
+
+/* This array maps the arguments to the register number which passes argument
+   in function call according to C6000 ELF ABI.  */
+static const int arg_regs[] = { 4, 20, 6, 22, 8, 24, 10, 26, 12, 28 };
+
+/* This is the implementation of gdbarch method register_name.  */
+
+static const char *
+tic6x_register_name (struct gdbarch *gdbarch, int regno)
+{
+  if (regno < 0)
+    return NULL;
+
+  if (tdesc_has_registers (gdbarch_target_desc (gdbarch)))
+    return tdesc_register_name (gdbarch, regno);
+  else if (regno >= ARRAY_SIZE (tic6x_register_names))
+    return "";
+  else
+    return tic6x_register_names[regno];
+}
+
+/* This is the implementation of gdbarch method register_type.  */
+
+static struct type *
+tic6x_register_type (struct gdbarch *gdbarch, int regno)
+{
+
+  if (regno == TIC6X_PC_REGNUM)
+    return builtin_type (gdbarch)->builtin_func_ptr;
+  else
+    return builtin_type (gdbarch)->builtin_uint32;
+}
+
+static void
+tic6x_setup_default (struct tic6x_unwind_cache *cache)
+{
+  int i;
+
+  for (i = 0; i < TIC6X_NUM_CORE_REGS; i++)
+    cache->reg_saved[i] = -1;
+}
+
+static unsigned long tic6x_fetch_instruction (struct gdbarch *, CORE_ADDR);
+static int tic6x_register_number (int reg, int side, int crosspath);
+
+/* Do a full analysis of the prologue at START_PC and update CACHE accordingly.
+   Bail out early if CURRENT_PC is reached.  Returns the address of the first
+   instruction after the prologue.  */
+
+CORE_ADDR
+tic6x_analyze_prologue (struct gdbarch *gdbarch, const CORE_ADDR start_pc,
+			const CORE_ADDR current_pc,
+			struct tic6x_unwind_cache *cache,
+			struct frame_info *this_frame)
+{
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  unsigned long inst;
+  unsigned int src_reg, base_reg, dst_reg;
+  int i;
+  CORE_ADDR pc = start_pc;
+  CORE_ADDR return_pc = start_pc;
+  int frame_base_offset_to_sp = 0;
+  /* Counter of non-stw instructions after first insn ` sub sp, xxx, sp'.  */
+  int non_stw_insn_counter = 0;
+
+  if (start_pc >= current_pc)
+    return_pc = current_pc;
+
+  cache->base = 0;
+
+  /* The landmarks in prologue is one or two SUB instructions to SP.
+     Instructions on setting up dsbt are in the last part of prologue, if
+     needed.  In maxim, prologue can be divided to three parts by two
+     `sub sp, xx, sp' insns.  */
+
+  /* Step 1: Look for the 1st and 2nd insn `sub sp, xx, sp',  in which, the
+     2nd one is optional.  */
+  while (pc < current_pc)
+    {
+      int offset = 0;
+
+      unsigned long inst = tic6x_fetch_instruction (gdbarch, pc);
+
+      if ((inst & 0x1ffc) == 0x1dc0 || (inst & 0x1ffc) == 0x1bc0
+	  || (inst & 0x0ffc) == 0x9c0)
+	{
+	  /* SUBAW/SUBAH/SUB, and src1 is ucst 5.  */
+	  unsigned int src2 = tic6x_register_number ((inst >> 18) & 0x1f,
+						     INST_S_BIT (inst), 0);
+	  unsigned int dst = tic6x_register_number ((inst >> 23) & 0x1f,
+						    INST_S_BIT (inst), 0);
+
+	  if (src2 == TIC6X_SP_REGNUM && dst == TIC6X_SP_REGNUM)
+	    {
+	      /* Extract const from insn SUBAW/SUBAH/SUB, and translate it to
+		 offset.  The constant offset is decoded in bit 13-17 in all
+		 these three kinds of instructions.  */
+	      unsigned int ucst5 = (inst >> 13) & 0x1f;
+
+	      if ((inst & 0x1ffc) == 0x1dc0)	/* SUBAW */
+		frame_base_offset_to_sp += ucst5 << 2;
+	      else if ((inst & 0x1ffc) == 0x1bc0)	/* SUBAH */
+		frame_base_offset_to_sp += ucst5 << 1;
+	      else if ((inst & 0x0ffc) == 0x9c0)	/* SUB */
+		frame_base_offset_to_sp += ucst5;
+	      else
+		gdb_assert_not_reached ("unexpected instruction");
+
+	      return_pc = pc + 4;
+	    }
+	}
+      else if ((inst & 0x174) == 0x74)	/* stw SRC, *+b15(uconst) */
+	{
+	  /* The y bit determines which file base is read from.  */
+	  base_reg = tic6x_register_number ((inst >> 18) & 0x1f,
+					    (inst >> 7) & 1, 0);
+
+	  if (base_reg == TIC6X_SP_REGNUM)
+	    {
+	      src_reg = tic6x_register_number ((inst >> 23) & 0x1f,
+					       INST_S_BIT (inst), 0);
+
+	      cache->reg_saved[src_reg] = ((inst >> 13) & 0x1f) << 2;
+
+	      return_pc = pc + 4;
+	    }
+	  non_stw_insn_counter = 0;
+	}
+      else
+	{
+	  non_stw_insn_counter++;
+	  /* Following instruction sequence may be emitted in prologue:
+
+	     <+0>: subah .D2 b15,28,b15
+	     <+4>: or .L2X 0,a4,b0
+	     <+8>: || stw .D2T2 b14,*+b15(56)
+	     <+12>:[!b0] b .S1 0xe50e4c1c <sleep+220>
+	     <+16>:|| stw .D2T1 a10,*+b15(48)
+	     <+20>:stw .D2T2 b3,*+b15(52)
+	     <+24>:stw .D2T1 a4,*+b15(40)
+
+	     we should look forward for next instruction instead of breaking loop
+	     here.  So far, we allow almost two sequential non-stw instructions
+	     in prologue.  */
+	  if (non_stw_insn_counter >= 2)
+	    break;
+	}
+
+
+      pc += 4;
+    }
+  /* Step 2: Skip insn on setting up dsbt if it is.  Usually, it looks like,
+     ldw .D2T2 *+b14(0),b14 */
+  inst = tic6x_fetch_instruction (gdbarch, pc);
+  /* The s bit determines which file dst will be loaded into, same effect as
+     other places.  */
+  dst_reg = tic6x_register_number ((inst >> 23) & 0x1f, (inst >> 1) & 1, 0);
+  /* The y bit (bit 7), instead of s bit, determines which file base be
+     used.  */
+  base_reg = tic6x_register_number ((inst >> 18) & 0x1f, (inst >> 7) & 1, 0);
+
+  if ((inst & 0x164) == 0x64	/* ldw */
+      && dst_reg == TIC6X_DP_REGNUM	/* dst is B14 */
+      && base_reg == TIC6X_DP_REGNUM)	/* baseR is B14 */
+    {
+      return_pc = pc + 4;
+    }
+
+  if (this_frame)
+    {
+      cache->base = get_frame_register_unsigned (this_frame, TIC6X_SP_REGNUM);
+
+      if (cache->reg_saved[TIC6X_FP_REGNUM] != -1)
+	{
+	  /* If the FP now holds an offset from the CFA then this is a frame
+	     which uses the frame pointer.  */
+
+	  cache->cfa = get_frame_register_unsigned (this_frame,
+						    TIC6X_FP_REGNUM);
+	}
+      else
+	{
+	  /* FP doesn't hold an offset from the CFA.  If SP still holds an
+	     offset from the CFA then we might be in a function which omits
+	     the frame pointer.  */
+
+	  cache->cfa = cache->base + frame_base_offset_to_sp;
+	}
+    }
+
+  /* Adjust all the saved registers such that they contain addresses
+     instead of offsets.  */
+  for (i = 0; i < TIC6X_NUM_CORE_REGS; i++)
+    if (cache->reg_saved[i] != -1)
+      cache->reg_saved[i] = cache->base + cache->reg_saved[i];
+
+  return return_pc;
+}
+
+/* This is the implementation of gdbarch method skip_prologue.  */
+
+CORE_ADDR
+tic6x_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR start_pc)
+{
+  CORE_ADDR limit_pc;
+  CORE_ADDR func_addr;
+  struct tic6x_unwind_cache cache;
+
+  /* See if we can determine the end of the prologue via the symbol table.
+     If so, then return either PC, or the PC after the prologue, whichever is
+     greater.  */
+  if (find_pc_partial_function (start_pc, NULL, &func_addr, NULL))
+    {
+      CORE_ADDR post_prologue_pc
+	= skip_prologue_using_sal (gdbarch, func_addr);
+      if (post_prologue_pc != 0)
+	return max (start_pc, post_prologue_pc);
+    }
+
+  /* Can't determine prologue from the symbol table, need to examine
+     instructions.  */
+  return tic6x_analyze_prologue (gdbarch, start_pc, (CORE_ADDR) -1, &cache,
+				 NULL);
+}
+
+/* This is the implementation of gdbarch method breakpiont_from_pc.  */
+
+const unsigned char*
+tic6x_breakpoint_from_pc (struct gdbarch *gdbarch, CORE_ADDR *bp_addr,
+			  int *bp_size)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
+  *bp_size = 4;
+
+  if (tdep == NULL || tdep->breakpoint == NULL)
+    {
+      if (BFD_ENDIAN_BIG == gdbarch_byte_order_for_code (gdbarch))
+	return tic6x_bkpt_illegal_opcode_be;
+      else
+	return tic6x_bkpt_illegal_opcode_le;
+    }
+  else
+    return tdep->breakpoint;
+}
+
+/* This is the implementation of gdbarch method print_insn.  */
+
+static int
+tic6x_print_insn (bfd_vma memaddr, disassemble_info *info)
+{
+  return print_insn_tic6x (memaddr, info);
+}
+
+static void
+tic6x_dwarf2_frame_init_reg (struct gdbarch *gdbarch, int regnum,
+			     struct dwarf2_frame_state_reg *reg,
+			     struct frame_info *this_frame)
+{
+  /* Mark the PC as the destination for the return address.  */
+  if (regnum == gdbarch_pc_regnum (gdbarch))
+    reg->how = DWARF2_FRAME_REG_RA;
+
+  /* Mark the stack pointer as the call frame address.  */
+  else if (regnum == gdbarch_sp_regnum (gdbarch))
+    reg->how = DWARF2_FRAME_REG_CFA;
+
+  /* The above was taken from the default init_reg in dwarf2-frame.c
+     while the below is c6x specific.  */
+
+  /* Callee save registers.  The ABI designates A10-A15 and B10-B15 as
+     callee-save.  */
+  else if ((regnum >= 10 && regnum <= 15) || (regnum >= 26 && regnum <= 31))
+    reg->how = DWARF2_FRAME_REG_SAME_VALUE;
+  else
+    /* All other registers are caller-save.  */
+    reg->how = DWARF2_FRAME_REG_UNDEFINED;
+}
+
+/* This is the implementation of gdbarch method unwind_pc.  */
+
+static CORE_ADDR
+tic6x_unwind_pc (struct gdbarch *gdbarch, struct frame_info *next_frame)
+{
+  gdb_byte buf[8];
+
+  frame_unwind_register (next_frame,  TIC6X_PC_REGNUM, buf);
+  return extract_typed_address (buf, builtin_type (gdbarch)->builtin_func_ptr);
+}
+
+/* This is the implementation of gdbarch method unwind_sp.  */
+
+static CORE_ADDR
+tic6x_unwind_sp (struct gdbarch *gdbarch, struct frame_info *this_frame)
+{
+  return frame_unwind_register_unsigned (this_frame, TIC6X_SP_REGNUM);
+}
+
+
+/* Frame base handling.  */
+
+struct tic6x_unwind_cache*
+tic6x_frame_unwind_cache (struct frame_info *this_frame,
+			  void **this_prologue_cache)
+{
+  struct gdbarch *gdbarch = get_frame_arch (this_frame);
+  CORE_ADDR current_pc;
+  struct tic6x_unwind_cache *cache;
+  int i;
+
+  if (*this_prologue_cache)
+    return *this_prologue_cache;
+
+  cache = FRAME_OBSTACK_ZALLOC (struct tic6x_unwind_cache);
+  (*this_prologue_cache) = cache;
+
+  cache->return_regnum = TIC6X_RA_REGNUM;
+
+  tic6x_setup_default (cache);
+
+  cache->pc = get_frame_func (this_frame);
+  current_pc = get_frame_pc (this_frame);
+
+  /* Prologue analysis does the rest...  */
+  if (cache->pc != 0)
+    tic6x_analyze_prologue (gdbarch, cache->pc, current_pc, cache, this_frame);
+
+  return cache;
+}
+
+static void
+tic6x_frame_this_id (struct frame_info *this_frame, void **this_cache,
+		     struct frame_id *this_id)
+{
+  struct tic6x_unwind_cache *cache =
+    tic6x_frame_unwind_cache (this_frame, this_cache);
+
+  /* This marks the outermost frame.  */
+  if (cache->base == 0)
+    return;
+
+  (*this_id) = frame_id_build (cache->cfa, cache->pc);
+}
+
+static struct value *
+tic6x_frame_prev_register (struct frame_info *this_frame, void **this_cache,
+			   int regnum)
+{
+  struct tic6x_unwind_cache *cache =
+    tic6x_frame_unwind_cache (this_frame, this_cache);
+
+  gdb_assert (regnum >= 0);
+
+  /* The PC of the previous frame is stored in the RA register of
+     the current frame.  Frob regnum so that we pull the value from
+     the correct place.  */
+  if (regnum == TIC6X_PC_REGNUM)
+    regnum = cache->return_regnum;
+
+  if (regnum == TIC6X_SP_REGNUM && cache->cfa)
+    return frame_unwind_got_constant (this_frame, regnum, cache->cfa);
+
+  /* If we've worked out where a register is stored then load it from
+     there.  */
+  if (regnum < TIC6X_NUM_CORE_REGS && cache->reg_saved[regnum] != -1)
+    return frame_unwind_got_memory (this_frame, regnum,
+				    cache->reg_saved[regnum]);
+
+  return frame_unwind_got_register (this_frame, regnum, regnum);
+}
+
+static CORE_ADDR
+tic6x_frame_base_address (struct frame_info *this_frame, void **this_cache)
+{
+  struct tic6x_unwind_cache *info
+    = tic6x_frame_unwind_cache (this_frame, this_cache);
+  return info->base;
+}
+
+static const struct frame_unwind tic6x_frame_unwind =
+{
+  NORMAL_FRAME,
+  default_frame_unwind_stop_reason,
+  tic6x_frame_this_id,
+  tic6x_frame_prev_register,
+  NULL,
+  default_frame_sniffer
+};
+
+static const struct frame_base tic6x_frame_base =
+{
+  &tic6x_frame_unwind,
+  tic6x_frame_base_address,
+  tic6x_frame_base_address,
+  tic6x_frame_base_address
+};
+
+
+static struct tic6x_unwind_cache *
+tic6x_make_stub_cache (struct frame_info *this_frame)
+{
+  struct tic6x_unwind_cache *cache;
+
+  cache = FRAME_OBSTACK_ZALLOC (struct tic6x_unwind_cache);
+
+  cache->return_regnum = TIC6X_RA_REGNUM;
+
+  tic6x_setup_default (cache);
+
+  cache->cfa = get_frame_register_unsigned (this_frame, TIC6X_SP_REGNUM);
+
+  return cache;
+}
+
+static void
+tic6x_stub_this_id (struct frame_info *this_frame, void **this_cache,
+		    struct frame_id *this_id)
+{
+  struct tic6x_unwind_cache *cache;
+
+  if (*this_cache == NULL)
+    *this_cache = tic6x_make_stub_cache (this_frame);
+  cache = *this_cache;
+
+  *this_id = frame_id_build (cache->cfa, get_frame_pc (this_frame));
+}
+
+static int
+tic6x_stub_unwind_sniffer (const struct frame_unwind *self,
+			   struct frame_info *this_frame,
+			   void **this_prologue_cache)
+{
+  CORE_ADDR addr_in_block;
+
+  addr_in_block = get_frame_address_in_block (this_frame);
+  if (in_plt_section (addr_in_block, NULL))
+    return 1;
+
+  return 0;
+}
+
+static const struct frame_unwind tic6x_stub_unwind =
+{
+  NORMAL_FRAME,
+  default_frame_unwind_stop_reason,
+  tic6x_stub_this_id,
+  tic6x_frame_prev_register,
+  NULL,
+  tic6x_stub_unwind_sniffer
+};
+
+/* Return the instruction on address PC.  */
+
+static unsigned long
+tic6x_fetch_instruction (struct gdbarch *gdbarch, CORE_ADDR pc)
+{
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  return read_memory_unsigned_integer (pc, TIC6X_OPCODE_SIZE, byte_order);
+}
+
+/* Compute the condition of INST if it is a conditional instruction.  Always
+   return 1 if INST is not a conditional instruction.  */
+
+static int
+tic6x_condition_true (struct frame_info *frame, unsigned long inst)
+{
+  int register_number;
+  int register_value;
+  static const int register_numbers[8] = { -1, 16, 17, 18, 1, 2, 0, -1 };
+
+  register_number = register_numbers[(inst >> 29) & 7];
+  if (register_number == -1)
+    return 1;
+
+  register_value = get_frame_register_signed (frame, register_number);
+  if ((inst & 0x10000000) != 0)
+    return register_value == 0;
+  return register_value != 0;
+}
+
+/* Get the register number by decoding raw bits REG, SIDE, and CROSSPATH in
+   instruction.  */
+
+static int
+tic6x_register_number (int reg, int side, int crosspath)
+{
+  int r = (reg & 15) | ((crosspath ^ side) << 4);
+  if ((reg & 16) != 0) /* A16 - A31, B16 - B31 */
+    r += 37;
+  return r;
+}
+
+static int
+tic6x_extract_signed_field (int value, int low_bit, int bits)
+{
+  int mask = (1 << bits) - 1;
+  int r = (value >> low_bit) & mask;
+  if ((r & (1 << (bits - 1))) != 0)
+    r -= mask + 1;
+  return r;
+}
+
+/* Determine where to set a single step breakpoint.  */
+
+static CORE_ADDR
+tic6x_get_next_pc (struct frame_info *frame, CORE_ADDR pc)
+{
+  struct gdbarch *gdbarch = get_frame_arch (frame);
+  unsigned long inst;
+  int offset;
+  int register_number;
+  int last = 0;
+
+  do
+    {
+      inst = tic6x_fetch_instruction (gdbarch, pc);
+
+      last = !(inst & 1);
+
+      if (inst == TIC6X_INST_SWE)
+	{
+	  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
+	  if (tdep->syscall_next_pc != NULL)
+	    return tdep->syscall_next_pc (frame);
+	}
+
+      if (tic6x_condition_true (frame, inst))
+	{
+	  if ((inst & 0x0000007c) == 0x00000010)
+	    {
+	      /* B with displacement */
+	      pc &= ~(TIC6X_FETCH_PACKET_SIZE - 1);
+	      pc += tic6x_extract_signed_field (inst, 7, 21) << 2;
+	      break;
+	    }
+	  if ((inst & 0x0f83effc) == 0x00000360)
+	    {
+	      /* B with register */
+
+	      register_number = tic6x_register_number ((inst >> 18) & 0x1f,
+						       INST_S_BIT (inst),
+						       INST_X_BIT (inst));
+	      pc = get_frame_register_unsigned (frame, register_number);
+	      break;
+	    }
+	  if ((inst & 0x00001ffc) == 0x00001020)
+	    {
+	      /* BDEC */
+	      register_number = tic6x_register_number ((inst >> 23) & 0x1f,
+						       INST_S_BIT (inst), 0);
+	      if (get_frame_register_signed (frame, register_number) >= 0)
+		{
+		  pc &= ~(TIC6X_FETCH_PACKET_SIZE - 1);
+		  pc += tic6x_extract_signed_field (inst, 7, 10) << 2;
+		}
+	      break;
+	    }
+	  if ((inst & 0x00001ffc) == 0x00000120)
+	    {
+	      /* BNOP with displacement */
+	      pc &= ~(TIC6X_FETCH_PACKET_SIZE - 1);
+	      pc += tic6x_extract_signed_field (inst, 16, 12) << 2;
+	      break;
+	    }
+	  if ((inst & 0x0f830ffe) == 0x00800362)
+	    {
+	      /* BNOP with register */
+	      register_number = tic6x_register_number ((inst >> 18) & 0x1f,
+						       1, INST_X_BIT (inst));
+	      pc = get_frame_register_unsigned (frame, register_number);
+	      break;
+	    }
+	  if ((inst & 0x00001ffc) == 0x00000020)
+	    {
+	      /* BPOS */
+	      register_number = tic6x_register_number ((inst >> 23) & 0x1f,
+						       INST_S_BIT (inst), 0);
+	      if (get_frame_register_signed (frame, register_number) >= 0)
+		{
+		  pc &= ~(TIC6X_FETCH_PACKET_SIZE - 1);
+		  pc += tic6x_extract_signed_field (inst, 13, 10) << 2;
+		}
+	      break;
+	    }
+	  if ((inst & 0xf000007c) == 0x10000010)
+	    {
+	      /* CALLP */
+	      pc &= ~(TIC6X_FETCH_PACKET_SIZE - 1);
+	      pc += tic6x_extract_signed_field (inst, 7, 21) << 2;
+	      break;
+	    }
+	}
+      pc += TIC6X_OPCODE_SIZE;
+    }
+  while (!last);
+  return pc;
+}
+
+/* This is the implementation of gdbarch method software_single_step.  */
+
+int
+tic6x_software_single_step (struct frame_info *frame)
+{
+  struct gdbarch *gdbarch = get_frame_arch (frame);
+  struct address_space *aspace = get_frame_address_space (frame);
+  CORE_ADDR next_pc = tic6x_get_next_pc (frame, get_frame_pc (frame));
+
+  insert_single_step_breakpoint (gdbarch, aspace, next_pc);
+
+  return 1;
+}
+
+/* This is the implementation of gdbarch method frame_align.  */
+
+static CORE_ADDR
+tic6x_frame_align (struct gdbarch *gdbarch, CORE_ADDR addr)
+{
+  return align_down (addr, 8);
+}
+
+/* This is the implementation of gdbarch method register_to_value.  */
+
+static int
+tic6x_register_to_value (struct frame_info *frame, int regnum,
+			 struct type *type, gdb_byte * to,
+			 int *optimizedp, int *unavailablep)
+{
+  get_frame_register (frame, regnum, (char *) to);
+  *optimizedp = *unavailablep = 0;
+  return 1;
+}
+
+/* This is the implementation of gdbarch method value_to_register.  */
+
+static void
+tic6x_value_to_register (struct frame_info *frame, int regnum,
+			 struct type *type, const gdb_byte *from)
+{
+  put_frame_register (frame, regnum, from);
+}
+
+/* Given a return value in REGCACHE with a type VALTYPE, extract and copy its
+   value into VALBUF.  */
+
+static void
+tic6x_extract_return_value (struct type *valtype, struct regcache *regcache,
+			    enum bfd_endian byte_order, gdb_byte *valbuf)
+{
+  int len = TYPE_LENGTH (valtype);
+
+  /* pointer types are returned in register A4,
+     up to 32-bit types in A4
+     up to 64-bit types in A5:A4  */
+  if (len <= 4)
+    {
+      /* In big-endian,
+	 - one-byte structure or union occupies the LSB of single even register.
+	 - for two-byte structure or union, the first byte occupies byte 1 of
+	 register and the second byte occupies byte 0.
+	 so, we read the contents in VAL from the LSBs of register.  */
+      if (len < 3 && byte_order == BFD_ENDIAN_BIG)
+	regcache_cooked_read_part (regcache, TIC6X_A4_REGNUM, 4 - len, len,
+				   valbuf);
+      else
+	regcache_cooked_read (regcache, TIC6X_A4_REGNUM, valbuf);
+    }
+  else if (len <= 8)
+    {
+      /* For a 5-8 byte structure or union in big-endian, the first byte
+	 occupies byte 3 (the MSB) of the upper (odd) register and the
+	 remaining bytes fill the decreasingly significant bytes.  5-7
+	 byte structures or unions have padding in the LSBs of the
+	 lower (even) register.  */
+      if (byte_order == BFD_ENDIAN_BIG)
+	{
+	  regcache_cooked_read (regcache, TIC6X_A4_REGNUM, valbuf + 4);
+	  regcache_cooked_read (regcache, TIC6X_A5_REGNUM, valbuf);
+	}
+      else
+	{
+	  regcache_cooked_read (regcache, TIC6X_A4_REGNUM, valbuf);
+	  regcache_cooked_read (regcache, TIC6X_A5_REGNUM, valbuf + 4);
+	}
+    }
+}
+
+/* Write into appropriate registers a function return value
+   of type TYPE, given in virtual format.  */
+
+static void
+tic6x_store_return_value (struct type *valtype, struct regcache *regcache,
+			  enum bfd_endian byte_order, const gdb_byte *valbuf)
+{
+  int len = TYPE_LENGTH (valtype);
+
+  /* return values of up to 8 bytes are returned in A5:A4 */
+
+  if (len <= 4)
+    {
+      if (len < 3 && byte_order == BFD_ENDIAN_BIG)
+	regcache_cooked_write_part (regcache, TIC6X_A4_REGNUM, 4 - len, len,
+				    valbuf);
+      else
+	regcache_cooked_write (regcache, TIC6X_A4_REGNUM, valbuf);
+    }
+  else if (len <= 8)
+    {
+      if (byte_order == BFD_ENDIAN_BIG)
+	{
+	  regcache_cooked_write (regcache, TIC6X_A4_REGNUM, valbuf + 4);
+	  regcache_cooked_write (regcache, TIC6X_A5_REGNUM, valbuf);
+	}
+      else
+	{
+	  regcache_cooked_write (regcache, TIC6X_A4_REGNUM, valbuf);
+	  regcache_cooked_write (regcache, TIC6X_A5_REGNUM, valbuf + 4);
+	}
+    }
+}
+
+/* This is the implementation of gdbarch method return_value.  */
+
+static enum return_value_convention
+tic6x_return_value (struct gdbarch *gdbarch, struct type *func_type,
+		    struct type *type, struct regcache *regcache,
+		    gdb_byte *readbuf, const gdb_byte *writebuf)
+{
+  if (TYPE_LENGTH (type) > 8)
+    return RETURN_VALUE_STRUCT_CONVENTION;
+
+  if (readbuf)
+    tic6x_extract_return_value (type, regcache,
+				gdbarch_byte_order (gdbarch), readbuf);
+  if (writebuf)
+    tic6x_store_return_value (type, regcache,
+			      gdbarch_byte_order (gdbarch), writebuf);
+
+  return RETURN_VALUE_REGISTER_CONVENTION;
+}
+
+/* This is the implementation of gdbarch method dummy_id.  */
+
+static struct frame_id
+tic6x_dummy_id (struct gdbarch *gdbarch, struct frame_info *this_frame)
+{
+  return frame_id_build
+    (get_frame_register_unsigned (this_frame, TIC6X_SP_REGNUM),
+     get_frame_pc (this_frame));
+}
+
+/* Get the alignment requirement of TYPE.  */
+
+static int
+tic6x_arg_type_alignment (struct type *type)
+{
+  int len = TYPE_LENGTH (check_typedef (type));
+  enum type_code typecode = TYPE_CODE (check_typedef (type));
+
+  if (typecode == TYPE_CODE_STRUCT || typecode == TYPE_CODE_UNION)
+    {
+      /* The stack alignment of a structure (and union) passed by value is the
+	 smallest power of two greater than or equal to its size.
+	 This cannot exceed 8 bytes, which is the largest allowable size for
+	 a structure passed by value.  */
+
+      if (len <= 2)
+	return len;
+      else if (len <= 4)
+	return 4;
+      else if (len <= 8)
+	return 8;
+      else
+	gdb_assert_not_reached ("unexpected length of data");
+    }
+  else
+    {
+      if (len <= 4)
+	return 4;
+      else if (len == 8)
+	{
+	  if (typecode == TYPE_CODE_COMPLEX)
+	    return 4;
+	  else
+	    return 8;
+	}
+      else if (len == 16)
+	{
+	  if (typecode == TYPE_CODE_COMPLEX)
+	    return 8;
+	  else
+	    return 16;
+	}
+      else
+	internal_error (__FILE__, __LINE__, _("unexpected length %d of type"),
+			len);
+    }
+}
+
+/* This is the implementation of gdbarch method push_dummy_call.  */
+
+static CORE_ADDR
+tic6x_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
+		       struct regcache *regcache, CORE_ADDR bp_addr,
+		       int nargs, struct value **args, CORE_ADDR sp,
+		       int struct_return, CORE_ADDR struct_addr)
+{
+  int argreg = 0;
+  int argnum;
+  int len = 0;
+  int stack_offset = 4;
+  int references_offset = 4;
+  CORE_ADDR func_addr = find_function_addr (function, NULL);
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  struct type *func_type = value_type (function);
+  /* The first arg passed on stack.  Mostly the first 10 args are passed by
+     registers.  */
+  int first_arg_on_stack = 10;
+  /* If this inf-call is a cpp method call, and return value is passed by
+     reference, this flag is set to 1, otherwise set to 0.  We need this flag
+     because computation of the return location in
+     infcall.c:call_function_by_hand is wrong for C6000 ELF ABI.  In
+     call_function_by_hand, the language is considered first, and then
+     target ABI is considered.  If language_pass_by_reference returns true,
+     the return location is passed as the first parameter to the function,
+     which is conflict with C6000 ELF ABI.  If this flag is true, we should
+     adjust args and return locations accordingly to comply with C6000 ELF
+     ABI.  */
+  int cplus_return_struct_by_reference = 0;
+
+  if (current_language->la_language == language_cplus)
+    {
+      struct type *values_type;
+
+      find_function_addr (function, &values_type);
+
+      if (values_type)
+	{
+	  CHECK_TYPEDEF (values_type);
+	  if (language_pass_by_reference (values_type))
+	    cplus_return_struct_by_reference = 1;
+	}
+
+    }
+  /* Set the return address register to point to the entry point of
+     the program, where a breakpoint lies in wait.  */
+  regcache_cooked_write_unsigned (regcache, TIC6X_RA_REGNUM, bp_addr);
+
+  /* The caller must pass an argument in A3 containing a destination address
+     for the returned value.  The callee returns the object by copying it to
+     the address in A3.  */
+  if (struct_return)
+    regcache_cooked_write_unsigned (regcache, 3, struct_addr);
+  else if (cplus_return_struct_by_reference)
+    /* When cplus_return_struct_by_reference is 1, means local variable
+       lang_struct_return in call_function_by_hand is 1, so struct is
+       returned by reference, even STRUCT_RETURN is 0.  Note that STRUCT_ADDR
+       is still valid in this case.  */
+    regcache_cooked_write_unsigned (regcache, 3, struct_addr);
+
+  /* Determine the type of this function.  */
+  func_type = check_typedef (func_type);
+  if (TYPE_CODE (func_type) == TYPE_CODE_PTR)
+    func_type = check_typedef (TYPE_TARGET_TYPE (func_type));
+
+  gdb_assert (TYPE_CODE (func_type) == TYPE_CODE_FUNC
+	      || TYPE_CODE (func_type) == TYPE_CODE_METHOD);
+
+  /* For a variadic C function, the last explicitly declared argument and all
+     remaining arguments are passed on the stack.  */
+  if (TYPE_VARARGS (func_type))
+    first_arg_on_stack = TYPE_NFIELDS (func_type) - 1;
+
+  /* Now make space on the stack for the args.  If
+     cplus_return_struct_by_reference is 1, means GDB pass an extra parameter
+     in ARGS, which is useless here, skip it.  */
+  for (argnum = cplus_return_struct_by_reference; argnum < nargs; argnum++)
+    {
+      int len = align_up (TYPE_LENGTH (value_type (args[argnum])), 4);
+      if (argnum >= 10 - argreg)
+	references_offset += len;
+      stack_offset += len;
+    }
+  sp -= stack_offset;
+  /* SP should be 8-byte aligned, see C6000 ABI section 4.4.1
+     Stack Alignment.  */
+  sp = align_down (sp, 8);
+  stack_offset = 4;
+
+  /* Now load as many as possible of the first arguments into
+     registers, and push the rest onto the stack.  Loop through args
+     from first to last.  */
+  for (argnum = cplus_return_struct_by_reference; argnum < nargs; argnum++)
+    {
+      const gdb_byte *val;
+      struct value *arg = args[argnum];
+      struct type *arg_type = check_typedef (value_type (arg));
+      int len = TYPE_LENGTH (arg_type);
+      enum type_code typecode = TYPE_CODE (arg_type);
+
+      val = value_contents (arg);
+
+      /* Copy the argument to general registers or the stack in
+         register-sized pieces.  */
+      if (argreg < first_arg_on_stack)
+	{
+	  if (len <= 4)
+	    {
+	      if (typecode == TYPE_CODE_STRUCT || typecode == TYPE_CODE_UNION)
+		{
+		  /* In big-endian,
+		     - one-byte structure or union occupies the LSB of single
+		     even register.
+		     - for two-byte structure or union, the first byte
+		     occupies byte 1 of register and the second byte occupies
+		     byte 0.
+		     so, we write the contents in VAL to the lsp of
+		     register.  */
+		  if (len < 3 && byte_order == BFD_ENDIAN_BIG)
+		    regcache_cooked_write_part (regcache, arg_regs[argreg],
+						4 - len, len, val);
+		  else
+		    regcache_cooked_write (regcache, arg_regs[argreg], val);
+		}
+	      else
+		{
+		  /* The argument is being passed by value in a single
+		     register.  */
+		  CORE_ADDR regval = extract_unsigned_integer (val, len,
+							       byte_order);
+
+		  regcache_cooked_write_unsigned (regcache, arg_regs[argreg],
+						  regval);
+		}
+	    }
+	  else
+	    {
+	      if (len <= 8)
+		{
+		  if (typecode == TYPE_CODE_STRUCT
+		      || typecode == TYPE_CODE_UNION)
+		    {
+		      /* For a 5-8 byte structure or union in big-endian, the
+		         first byte occupies byte 3 (the MSB) of the upper (odd)
+		         register and the remaining bytes fill the decreasingly
+		         significant bytes.  5-7 byte structures or unions have
+		         padding in the LSBs of the lower (even) register.  */
+		      if (byte_order == BFD_ENDIAN_BIG)
+			{
+			  regcache_cooked_write (regcache,
+						 arg_regs[argreg] + 1, val);
+			  regcache_cooked_write_part (regcache,
+						      arg_regs[argreg], 0,
+						      len - 4, val + 4);
+			}
+		      else
+			{
+			  regcache_cooked_write (regcache, arg_regs[argreg],
+						 val);
+			  regcache_cooked_write_part (regcache,
+						      arg_regs[argreg] + 1, 0,
+						      len - 4, val + 4);
+			}
+		    }
+		  else
+		    {
+		      /* The argument is being passed by value in a pair of
+		         registers.  */
+		      ULONGEST regval = extract_unsigned_integer (val, len,
+								  byte_order);
+
+		      regcache_cooked_write_unsigned (regcache,
+						      arg_regs[argreg],
+						      regval);
+		      regcache_cooked_write_unsigned (regcache,
+						      arg_regs[argreg] + 1,
+						      regval >> 32);
+		    }
+		}
+	      else
+		{
+		  /* The argument is being passed by reference in a single
+		     register.  */
+		  CORE_ADDR addr;
+
+		  /* It is not necessary to adjust REFERENCES_OFFSET to
+		     8-byte aligned in some cases, in which 4-byte alignment
+		     is sufficient.  For simplicity, we adjust
+		     REFERENCES_OFFSET to 8-byte aligned.  */
+		  references_offset = align_up (references_offset, 8);
+
+		  addr = sp + references_offset;
+		  write_memory (addr, val, len);
+		  references_offset += align_up (len, 4);
+		  regcache_cooked_write_unsigned (regcache, arg_regs[argreg],
+						  addr);
+		}
+	    }
+	  argreg++;
+	}
+      else
+	{
+	  /* The argument is being passed on the stack.  */
+	  CORE_ADDR addr;
+
+	  /* There are six different cases of alignment, and these rules can
+	     be found in tic6x_arg_type_alignment:
+
+	     1) 4-byte aligned if size is less than or equal to 4 byte, such
+	     as short, int, struct, union etc.
+	     2) 8-byte aligned if size is less than or equal to 8-byte, such
+	     as double, long long,
+	     3) 4-byte aligned if it is of type _Complex float, even its size
+	     is 8-byte.
+	     4) 8-byte aligned if it is of type _Complex double or _Complex
+	     long double, even its size is 16-byte.  Because, the address of
+	     variable is passed as reference.
+	     5) struct and union larger than 8-byte are passed by reference, so
+	     it is 4-byte aligned.
+	     6) struct and union of size between 4 byte and 8 byte varies.
+	     alignment of struct variable is the alignment of its first field,
+	     while alignment of union variable is the max of all its fields'
+	     alignment.  */
+
+	  if (len <= 4)
+	    ; /* Default is 4-byte aligned.  Nothing to be done.  */
+	  else if (len <= 8)
+	    stack_offset = align_up (stack_offset,
+				     tic6x_arg_type_alignment (arg_type));
+	  else if (len == 16)
+	    {
+	      /* _Complex double or _Complex long double */
+	      if (typecode == TYPE_CODE_COMPLEX)
+		{
+		  /* The argument is being passed by reference on stack.  */
+		  CORE_ADDR addr;
+		  references_offset = align_up (references_offset, 8);
+
+		  addr = sp + references_offset;
+		  /* Store variable on stack.  */
+		  write_memory (addr, val, len);
+
+		  references_offset += align_up (len, 4);
+
+		  /* Pass the address of variable on stack as reference.  */
+		  store_unsigned_integer ((gdb_byte *) val, 4, byte_order,
+					  addr);
+		  len = 4;
+
+		}
+	      else
+		internal_error (__FILE__, __LINE__,
+				_("unexpected type %d of arg %d"),
+				typecode, argnum);
+	    }
+	  else
+	    internal_error (__FILE__, __LINE__,
+			    _("unexpected length %d of arg %d"), len, argnum);
+
+	  addr = sp + stack_offset;
+	  write_memory (addr, val, len);
+	  stack_offset += align_up (len, 4);
+	}
+    }
+
+  regcache_cooked_write_signed (regcache, TIC6X_SP_REGNUM, sp);
+
+  /* Return adjusted stack pointer.  */
+  return sp;
+}
+
+/* This is the implementation of gdbarch method in_function_epilogue_p.  */
+
+static int
+tic6x_in_function_epilogue_p (struct gdbarch *gdbarch, CORE_ADDR pc)
+{
+  unsigned long inst = tic6x_fetch_instruction (gdbarch, pc);
+  /* Normally, the epilogue is composed by instruction `b .S2 b3'.  */
+  if ((inst & 0x0f83effc) == 0x360)
+    {
+      unsigned int src2 = tic6x_register_number ((inst >> 18) & 0x1f,
+						 INST_S_BIT (inst),
+						 INST_X_BIT (inst));
+      if (src2 == TIC6X_RA_REGNUM)
+	return 1;
+    }
+
+  return 0;
+}
+
+/* This is the implementation of gdbarch method get_longjmp_target.  */
+
+static int
+tic6x_get_longjmp_target (struct frame_info *frame, CORE_ADDR *pc)
+{
+  struct gdbarch *gdbarch = get_frame_arch (frame);
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  CORE_ADDR jb_addr;
+  char buf[4];
+
+  /* JMP_BUF is passed by reference in A4.  */
+  jb_addr = get_frame_register_unsigned (frame, 4);
+
+  /* JMP_BUF contains 13 elements of type int, and return address is stored
+     in the last slot.  */
+  if (target_read_memory (jb_addr + 12 * 4, buf, 4))
+    return 0;
+
+  *pc = extract_unsigned_integer (buf, 4, byte_order);
+
+  return 1;
+}
+
+static struct gdbarch *
+tic6x_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
+{
+  struct gdbarch *gdbarch;
+  struct gdbarch_tdep *tdep;
+  struct tdesc_arch_data *tdesc_data = NULL;
+  const struct target_desc *tdesc = info.target_desc;
+  int has_gp = 0;
+
+  /* Check any target description for validity.  */
+  if (tdesc_has_registers (tdesc))
+    {
+      const struct tdesc_feature *feature;
+      int valid_p, i;
+
+      feature = tdesc_find_feature (tdesc, "org.gnu.gdb.tic6x.core");
+
+      if (feature == NULL)
+	return NULL;
+
+      tdesc_data = tdesc_data_alloc ();
+
+      valid_p = 1;
+      for (i = 0; i < 32; i++)	/* A0 - A15, B0 - B15 */
+	valid_p &= tdesc_numbered_register (feature, tdesc_data, i,
+					    tic6x_register_names[i]);
+
+      /* CSR */
+      valid_p &= tdesc_numbered_register (feature, tdesc_data, i++,
+					  tic6x_register_names[TIC6X_CSR_REGNUM]);
+      valid_p &= tdesc_numbered_register (feature, tdesc_data, i++,
+					  tic6x_register_names[TIC6X_PC_REGNUM]);
+
+      if (!valid_p)
+	{
+	  tdesc_data_cleanup (tdesc_data);
+	  return NULL;
+	}
+
+      feature = tdesc_find_feature (tdesc, "org.gnu.gdb.tic6x.gp");
+      if (feature)
+	{
+	  int j = 0;
+	  static const char *const gp[] =
+	    {
+	      "A16", "A17", "A18", "A19", "A20", "A21", "A22", "A23",
+	      "A24", "A25", "A26", "A27", "A28", "A29", "A30", "A31",
+	      "B16", "B17", "B18", "B19", "B20", "B21", "B22", "B23",
+	      "B24", "B25", "B26", "B27", "B28", "B29", "B30", "B31",
+	    };
+
+	  has_gp = 1;
+	  valid_p = 1;
+	  for (j = 0; j < 32; j++)	/* A16 - A31, B16 - B31 */
+	    valid_p &= tdesc_numbered_register (feature, tdesc_data, i++,
+						gp[j]);
+
+	  if (!valid_p)
+	    {
+	      tdesc_data_cleanup (tdesc_data);
+	      return NULL;
+	    }
+	}
+
+      feature = tdesc_find_feature (tdesc, "org.gnu.gdb.tic6x.c6xp");
+      if (feature)
+	{
+	  valid_p &= tdesc_numbered_register (feature, tdesc_data, i++, "TSR");
+	  valid_p &= tdesc_numbered_register (feature, tdesc_data, i++, "ILC");
+	  valid_p &= tdesc_numbered_register (feature, tdesc_data, i++, "RILC");
+
+	  if (!valid_p)
+	    {
+	      tdesc_data_cleanup (tdesc_data);
+	      return NULL;
+	    }
+	}
+
+    }
+
+  /* Find a candidate among extant architectures.  */
+  for (arches = gdbarch_list_lookup_by_info (arches, &info);
+       arches != NULL;
+       arches = gdbarch_list_lookup_by_info (arches->next, &info))
+    {
+      tdep = gdbarch_tdep (arches->gdbarch);
+
+      if (has_gp != tdep->has_gp)
+	continue;
+
+      if (tdep && tdep->breakpoint)
+	return arches->gdbarch;
+    }
+
+  tdep = xcalloc (1, sizeof (struct gdbarch_tdep));
+
+  tdep->has_gp = has_gp;
+  gdbarch = gdbarch_alloc (&info, tdep);
+
+  /* Data type sizes.  */
+  set_gdbarch_ptr_bit (gdbarch, 32);
+  set_gdbarch_addr_bit (gdbarch, 32);
+  set_gdbarch_short_bit (gdbarch, 16);
+  set_gdbarch_int_bit (gdbarch, 32);
+  set_gdbarch_long_bit (gdbarch, 32);
+  set_gdbarch_long_long_bit (gdbarch, 64);
+  set_gdbarch_float_bit (gdbarch, 32);
+  set_gdbarch_double_bit (gdbarch, 64);
+
+  set_gdbarch_float_format (gdbarch, floatformats_ieee_single);
+  set_gdbarch_double_format (gdbarch, floatformats_ieee_double);
+
+  /* The register set.  */
+  set_gdbarch_num_regs (gdbarch, TIC6X_NUM_REGS);
+  set_gdbarch_sp_regnum (gdbarch, TIC6X_SP_REGNUM);
+  set_gdbarch_pc_regnum (gdbarch, TIC6X_PC_REGNUM);
+
+  set_gdbarch_register_name (gdbarch, tic6x_register_name);
+  set_gdbarch_register_type (gdbarch, tic6x_register_type);
+
+  set_gdbarch_inner_than (gdbarch, core_addr_lessthan);
+
+  set_gdbarch_skip_prologue (gdbarch, tic6x_skip_prologue);
+  set_gdbarch_breakpoint_from_pc (gdbarch, tic6x_breakpoint_from_pc);
+
+  set_gdbarch_unwind_pc (gdbarch, tic6x_unwind_pc);
+  set_gdbarch_unwind_sp (gdbarch, tic6x_unwind_sp);
+
+  /* Unwinding.  */
+  dwarf2_append_unwinders (gdbarch);
+
+  frame_unwind_append_unwinder (gdbarch, &tic6x_stub_unwind);
+  frame_unwind_append_unwinder (gdbarch, &tic6x_frame_unwind);
+
+  dwarf2_frame_set_init_reg (gdbarch, tic6x_dwarf2_frame_init_reg);
+
+  /* Single stepping.  */
+  set_gdbarch_software_single_step (gdbarch, tic6x_software_single_step);
+
+  set_gdbarch_print_insn (gdbarch, tic6x_print_insn);
+
+  /* Call dummy code.  */
+  set_gdbarch_frame_align (gdbarch, tic6x_frame_align);
+
+  set_gdbarch_register_to_value (gdbarch, tic6x_register_to_value);
+  set_gdbarch_value_to_register (gdbarch, tic6x_value_to_register);
+
+  set_gdbarch_return_value (gdbarch, tic6x_return_value);
+
+  set_gdbarch_dummy_id (gdbarch, tic6x_dummy_id);
+
+  /* Enable inferior call support.  */
+  set_gdbarch_push_dummy_call (gdbarch, tic6x_push_dummy_call);
+
+  set_gdbarch_get_longjmp_target (gdbarch, tic6x_get_longjmp_target);
+
+  set_gdbarch_in_function_epilogue_p (gdbarch, tic6x_in_function_epilogue_p);
+
+  /* Hook in ABI-specific overrides, if they have been registered.  */
+  gdbarch_init_osabi (info, gdbarch);
+
+  if (tdesc_data)
+    tdesc_use_registers (gdbarch, tdesc, tdesc_data);
+
+  return gdbarch;
+}
+
+void
+_initialize_tic6x_tdep (void)
+{
+  register_gdbarch_init (bfd_arch_tic6x, tic6x_gdbarch_init);
+
+  initialize_tdesc_tic6x_c64xp ();
+  initialize_tdesc_tic6x_c64x ();
+  initialize_tdesc_tic6x_c62x ();
+}
diff --git a/gdb/tic6x-tdep.h b/gdb/tic6x-tdep.h
new file mode 100644
index 0000000..0227572
--- /dev/null
+++ b/gdb/tic6x-tdep.h
@@ -0,0 +1,54 @@
+/* GNU/Linux on  TI C6x target support.
+   Copyright (C) 2011
+   Free Software Foundation, Inc.
+   Contributed by Yao Qi <yao@codesourcery.com>
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+enum
+{
+  TIC6X_A4_REGNUM = 4,
+  TIC6X_A5_REGNUM = 5,
+  TIC6X_FP_REGNUM = 15,  /* Frame Pointer: A15 */
+  TIC6X_B0_REGNUM = 16,
+  TIC6X_RA_REGNUM = 19,  /* Return address: B3 */
+  TIC6X_B4_REGNUM = 20,
+  TIC6X_B5_REGNUM = 21,
+  TIC6X_DP_REGNUM = 30,  /* Data Page Pointer: B14 */
+  TIC6X_SP_REGNUM = 31,  /* Stack Pointer: B15 */
+  TIC6X_CSR_REGNUM = 32,
+  TIC6X_PC_REGNUM = 33,
+  TIC6X_NUM_CORE_REGS = 33, /* The number of core registers */
+  TIC6X_RILC_REGNUM = 68,
+  TIC6X_NUM_REGS /* The number of registers */
+};
+
+#define TIC6X_INST_SWE 0x10000000
+
+extern const gdb_byte tic6x_bkpt_illegal_opcode_be[];
+extern const gdb_byte tic6x_bkpt_illegal_opcode_le[];
+
+/* Target-dependent structure in gdbarch.  */
+struct gdbarch_tdep
+{
+  /* Return the expected next PC if FRAME is stopped at a syscall
+     instruction.  */
+  CORE_ADDR (*syscall_next_pc) (struct frame_info *frame);
+
+  const char *breakpoint; /* Breakpoint instruction.  */
+
+  int has_gp; /* Has general purpose registers A16 - A31 and B16 - B31.  */
+};
-- 
1.7.0.4


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