gdb: Add OpenRISC or1k and or1knd target support

This patch prepares the current GDB port of the OpenRISC processor from
https://github.com/openrisc/binutils-gdb for upstream merging.

Testing has been done with a cgen sim provided in a separate patch. This
has been tested with 2 toolchains. GCC [1] 5.4.0 from the OpenRISC
project with Newlib [2] and GCC 5.4.0 with Musl [3] 1.1.4.

It supports or1knd (no delay slot target).
The default target is or1k (with delay slot).

You can change the target arch with:

(gdb) set architecture or1knd
The target architecture is assumed to be or1knd

[1] https://github.com/openrisc/or1k-gcc
[2] https://github.com/openrisc/newlib
[3] https://github.com/openrisc/musl-cross

gdb/doc/ChangeLog:

2017-12-12  Stafford Horne  <shorne@gmail.com>
	    Stefan Wallentowitz  <stefan@wallentowitz.de>
	    Franck Jullien  <franck.jullien@gmail.com>
	    Jeremy Bennett  <jeremy.bennett@embecosm.com>

	* gdb.texinfo: Add OpenRISC documentation.

gdb/ChangeLog:

2017-12-12  Stafford Horne  <shorne@gmail.com>
	    Stefan Wallentowitz  <stefan@wallentowitz.de>
	    Stefan Kristiansson  <stefan.kristiansson@saunalahti.fi>
	    Franck Jullien  <franck.jullien@gmail.com>
	    Jeremy Bennett  <jeremy.bennett@embecosm.com>

	* configure.tgt: Add targets for or1k and or1knd.
	* or1k-tdep.c: New file.
	* or1k-tdep.h: New file.
	* features/Makefile: Add or1k.xml to build.
	* features/or1k.xml: New file.
	* features/or1k-core.xml: New file.
	* features/or1k.c: Generated.

1 files changed, 1294 insertions, 0 deletions

diff --git a/gdb/or1k-tdep.c b/gdb/or1k-tdep.c
new file mode 100644
index 00000000000..54b365e9586
--- /dev/null
+++ b/gdb/or1k-tdep.c
@@ -0,0 +1,1294 @@
+/* Target-dependent code for the 32-bit OpenRISC 1000, for the GDB.
+   Copyright (C) 2008-2017 Free Software Foundation, Inc.
+
+   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 "inferior.h"
+#include "symtab.h"
+#include "value.h"
+#include "gdbcmd.h"
+#include "language.h"
+#include "gdbcore.h"
+#include "symfile.h"
+#include "objfiles.h"
+#include "gdbtypes.h"
+#include "target.h"
+#include "regcache.h"
+#include "safe-ctype.h"
+#include "block.h"
+#include "reggroups.h"
+#include "arch-utils.h"
+#include "frame.h"
+#include "frame-unwind.h"
+#include "frame-base.h"
+#include "dwarf2-frame.h"
+#include "trad-frame.h"
+#include "regset.h"
+#include "remote.h"
+#include "target-descriptions.h"
+#include <inttypes.h>
+#include "dis-asm.h"
+
+/* OpenRISC specific includes.  */
+#include "or1k-tdep.h"
+#include "features/or1k.c"
+
+
+/* Global debug flag.  */
+
+static int or1k_debug = 0;
+
+static void
+show_or1k_debug (struct ui_file *file, int from_tty,
+		  struct cmd_list_element *c, const char *value)
+{
+  fprintf_filtered (file, _("OpenRISC debugging is %s.\n"), value);
+}
+
+
+/* The target-dependent structure for gdbarch.  */
+
+struct gdbarch_tdep
+{
+  int bytes_per_word;
+  int bytes_per_address;
+  CGEN_CPU_DESC gdb_cgen_cpu_desc;
+};
+
+/* Support functions for the architecture definition.  */
+
+/* Get an instruction from memory.  */
+
+static ULONGEST
+or1k_fetch_instruction (struct gdbarch *gdbarch, CORE_ADDR addr)
+{
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  gdb_byte buf[OR1K_INSTLEN];
+
+  if (target_read_code (addr, buf, OR1K_INSTLEN)) {
+    memory_error (TARGET_XFER_E_IO, addr);
+  }
+
+  return extract_unsigned_integer (buf, OR1K_INSTLEN, byte_order);
+}
+
+/* Generic function to read bits from an instruction.  */
+
+static bool
+or1k_analyse_inst (uint32_t inst, const char *format, ...)
+{
+  /* Break out each field in turn, validating as we go.  */
+  va_list ap;
+  int i;
+  int iptr = 0; /* Instruction pointer */
+
+  va_start (ap, format);
+
+  for (i = 0; 0 != format[i];)
+    {
+      const char *start_ptr;
+      char *end_ptr;
+
+      uint32_t bits; /* Bit substring of interest */
+      uint32_t width; /* Substring width */
+      uint32_t *arg_ptr;
+
+      switch (format[i])
+	{
+	case ' ':
+	  i++;
+	  break; /* Formatting: ignored */
+
+	case '0':
+	case '1': /* Constant bit field */
+	  bits = (inst >> (OR1K_INSTBITLEN - iptr - 1)) & 0x1;
+
+	  if ((format[i] - '0') != bits)
+	    return false;
+
+	  iptr++;
+	  i++;
+	  break;
+
+	case '%': /* Bit field */
+	  i++;
+	  start_ptr = &(format[i]);
+	  width = strtoul (start_ptr, &end_ptr, 10);
+
+	  /* Check we got something, and if so skip on.  */
+	  if (start_ptr == end_ptr)
+	    error ("bitstring \"%s\" at offset %d has no length field.\n",
+			format, i);
+
+	  i += end_ptr - start_ptr;
+
+	  /* Look for and skip the terminating 'b'.  If it's not there, we
+	     still give a fatal error, because these are fixed strings that
+	     just should not be wrong.  */
+	  if ('b' != format[i++])
+	    error ("bitstring \"%s\" at offset %d has no terminating 'b'.\n",
+			format, i);
+
+	  /* Break out the field.  There is a special case with a bit width
+	     of 32.  */
+	  if (32 == width)
+	    bits = inst;
+	  else
+	    bits =
+	      (inst >> (OR1K_INSTBITLEN - iptr - width)) & ((1 << width) - 1);
+
+	  arg_ptr = va_arg (ap, uint32_t *);
+	  *arg_ptr = bits;
+	  iptr += width;
+	  break;
+
+	default:
+	  error ("invalid character in bitstring \"%s\" at offset %d.\n",
+		      format, i);
+	  break;
+	}
+    }
+
+  /* Is the length OK?  */
+  gdb_assert (OR1K_INSTBITLEN == iptr);
+
+  return true; /* Success */
+}
+
+/* This is used to parse l.addi instructions during various prologue
+   analysis routines.  The l.addi instruction has semantics:
+
+     assembly:        l.addi  rD,rA,I
+     implementation:  rD = rA + sign_extend(Immediate)
+
+   The rd_ptr, ra_ptr and simm_ptr must be non NULL pointers and are used
+   to store the parse results.  Upon successful parsing true is returned,
+   false on failure. */
+
+static bool
+or1k_analyse_l_addi (uint32_t inst, unsigned int *rd_ptr,
+		     unsigned int *ra_ptr, int *simm_ptr)
+{
+  /* Instruction fields */
+  uint32_t rd, ra, i;
+
+  if (or1k_analyse_inst (inst, "10 0111 %5b %5b %16b", &rd, &ra, &i))
+    {
+      /* Found it.  Construct the result fields.  */
+      *rd_ptr = (unsigned int) rd;
+      *ra_ptr = (unsigned int) ra;
+      *simm_ptr = (int) (((i & 0x8000) == 0x8000) ? 0xffff0000 | i : i);
+
+      return true; /* Success */
+    }
+  else
+    return false; /* Failure */
+}
+
+/* This is used to to parse store instructions during various prologue
+   analysis routines.  The l.sw instruction has semantics:
+
+     assembly:        l.sw  I(rA),rB
+     implementation:  store rB contents to memory at effective address of
+		      rA + sign_extend(Immediate)
+
+   The simm_ptr, ra_ptr and rb_ptr must be non NULL pointers and are used
+   to store the parse results. Upon successful parsing true is returned,
+   false on failure. */
+
+static bool
+or1k_analyse_l_sw (uint32_t inst, int *simm_ptr, unsigned int *ra_ptr,
+		   unsigned int *rb_ptr)
+{
+  /* Instruction fields */
+  uint32_t ihi, ilo, ra, rb;
+
+  if (or1k_analyse_inst (inst, "11 0101 %5b %5b %5b %11b", &ihi, &ra, &rb,
+			 &ilo))
+
+    {
+      /* Found it.  Construct the result fields.  */
+      *simm_ptr = (int) ((ihi << 11) | ilo);
+      *simm_ptr |= ((ihi & 0x10) == 0x10) ? 0xffff0000 : 0;
+
+      *ra_ptr = (unsigned int) ra;
+      *rb_ptr = (unsigned int) rb;
+
+      return true; /* Success */
+    }
+  else
+    return false; /* Failure */
+}
+
+
+/* Functions defining the architecture.  */
+
+/* Implement the return_value gdbarch method.  */
+
+static enum return_value_convention
+or1k_return_value (struct gdbarch *gdbarch, struct value *functype,
+		   struct type *valtype, struct regcache *regcache,
+		   gdb_byte *readbuf, const gdb_byte *writebuf)
+{
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  enum type_code rv_type = TYPE_CODE (valtype);
+  unsigned int rv_size = TYPE_LENGTH (valtype);
+  int bpw = (gdbarch_tdep (gdbarch))->bytes_per_word;
+
+  /* Deal with struct/union as addresses.  If an array won't fit in a
+     single register it is returned as address.  Anything larger than 2
+     registers needs to also be passed as address (matches gcc
+     default_return_in_memory).  */
+  if ((TYPE_CODE_STRUCT == rv_type) || (TYPE_CODE_UNION == rv_type)
+      || ((TYPE_CODE_ARRAY == rv_type) && (rv_size > bpw))
+      || (rv_size > 2 * bpw))
+    {
+      if (readbuf != NULL)
+	{
+	  ULONGEST tmp;
+
+	  regcache_cooked_read_unsigned (regcache, OR1K_RV_REGNUM, &tmp);
+	  read_memory (tmp, readbuf, rv_size);
+	}
+      if (writebuf != NULL)
+	{
+	  ULONGEST tmp;
+
+	  regcache_cooked_read_unsigned (regcache, OR1K_RV_REGNUM, &tmp);
+	  write_memory (tmp, writebuf, rv_size);
+	}
+
+      return RETURN_VALUE_ABI_RETURNS_ADDRESS;
+    }
+
+  if (rv_size <= bpw)
+    {
+      /* Up to one word scalars are returned in R11.  */
+      if (readbuf != NULL)
+	{
+	  ULONGEST tmp;
+
+	  regcache_cooked_read_unsigned (regcache, OR1K_RV_REGNUM, &tmp);
+	  store_unsigned_integer (readbuf, rv_size, byte_order, tmp);
+
+	}
+      if (writebuf != NULL)
+	{
+	  gdb_byte *buf = XCNEWVEC(gdb_byte, bpw);
+
+	  if (BFD_ENDIAN_BIG == byte_order)
+	    memcpy (buf + (sizeof (gdb_byte) * bpw) - rv_size, writebuf,
+		    rv_size);
+	  else
+	    memcpy (buf, writebuf, rv_size);
+
+	  regcache_cooked_write (regcache, OR1K_RV_REGNUM, buf);
+
+	  free (buf);
+	}
+    }
+  else
+    {
+      /* 2 word scalars are returned in r11/r12 (with the MS word in r11).  */
+      if (readbuf != NULL)
+	{
+	  ULONGEST tmp_lo;
+	  ULONGEST tmp_hi;
+	  ULONGEST tmp;
+
+	  regcache_cooked_read_unsigned (regcache, OR1K_RV_REGNUM,
+					 &tmp_hi);
+	  regcache_cooked_read_unsigned (regcache, OR1K_RV_REGNUM + 1,
+					 &tmp_lo);
+	  tmp = (tmp_hi << (bpw * 8)) | tmp_lo;
+
+	  store_unsigned_integer (readbuf, rv_size, byte_order, tmp);
+	}
+      if (writebuf != NULL)
+	{
+	  gdb_byte *buf_lo = XCNEWVEC(gdb_byte, bpw);
+	  gdb_byte *buf_hi = XCNEWVEC(gdb_byte, bpw);
+
+	  /* This is cheating.  We assume that we fit in 2 words exactly,
+	     which wouldn't work if we had (say) a 6-byte scalar type on a
+	     big endian architecture (with the OpenRISC 1000 usually is).  */
+	  memcpy (buf_hi, writebuf, rv_size - bpw);
+	  memcpy (buf_lo, writebuf + bpw, bpw);
+
+	  regcache_cooked_write (regcache, OR1K_RV_REGNUM, buf_hi);
+	  regcache_cooked_write (regcache, OR1K_RV_REGNUM + 1, buf_lo);
+
+	  free (buf_lo);
+	  free (buf_hi);
+	}
+    }
+
+  return RETURN_VALUE_REGISTER_CONVENTION;
+}
+
+/* OR1K always uses a l.trap instruction for breakpoints.  */
+
+constexpr gdb_byte or1k_break_insn[] = {0x21, 0x00, 0x00, 0x01};
+
+typedef BP_MANIPULATION (or1k_break_insn) or1k_breakpoint;
+
+/* Implement the single_step_through_delay gdbarch method.  */
+
+static int
+or1k_single_step_through_delay (struct gdbarch *gdbarch,
+				struct frame_info *this_frame)
+{
+  ULONGEST val;
+  CORE_ADDR ppc;
+  CORE_ADDR npc;
+  CGEN_FIELDS tmp_fields;
+  const CGEN_INSN *insn;
+  struct regcache *regcache = get_current_regcache ();
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
+  /* Get the previous and current instruction addresses.  If they are not
+    adjacent, we cannot be in a delay slot.  */
+  regcache_cooked_read_unsigned (regcache, OR1K_PPC_REGNUM, &val);
+  ppc = (CORE_ADDR) val;
+  regcache_cooked_read_unsigned (regcache, OR1K_NPC_REGNUM, &val);
+  npc = (CORE_ADDR) val;
+
+  if (0x4 != (npc - ppc))
+    return 0;
+
+  insn = cgen_lookup_insn (tdep->gdb_cgen_cpu_desc,
+			    NULL,
+			    or1k_fetch_instruction (gdbarch, ppc),
+			    NULL, 32, &tmp_fields, 0);
+
+  /* NULL here would mean the last instruction was not understood by cgen.
+     This should not usually happen, but if does its not a delay slot.  */
+  if (insn == NULL)
+    return 0;
+
+  /* TODO: we should add a delay slot flag to the CGEN_INSN and remove
+     this hard coded test.  */
+  return ((CGEN_INSN_NUM (insn) == OR1K_INSN_L_J)
+	  || (CGEN_INSN_NUM (insn) == OR1K_INSN_L_JAL)
+	  || (CGEN_INSN_NUM (insn) == OR1K_INSN_L_JR)
+	  || (CGEN_INSN_NUM (insn) == OR1K_INSN_L_JALR)
+	  || (CGEN_INSN_NUM (insn) == OR1K_INSN_L_BNF)
+	  || (CGEN_INSN_NUM (insn) == OR1K_INSN_L_BF));
+}
+
+/* Name for or1k general registers.  */
+
+static const char *const or1k_reg_names[OR1K_NUM_REGS] = {
+  /* general purpose registers */
+  "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
+  "r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15",
+  "r16", "r17", "r18", "r19", "r20", "r21", "r22", "r23",
+  "r24", "r25", "r26", "r27", "r28", "r29", "r30", "r31",
+
+  /* previous program counter, next program counter and status register */
+  "ppc", "npc", "sr"
+};
+
+static int
+or1k_is_arg_reg (unsigned int regnum)
+{
+  return (OR1K_FIRST_ARG_REGNUM <= regnum)
+    && (regnum <= OR1K_LAST_ARG_REGNUM);
+}
+
+static int
+or1k_is_callee_saved_reg (unsigned int regnum)
+{
+  return (OR1K_FIRST_SAVED_REGNUM <= regnum) && (0 == regnum % 2);
+}
+
+/* Implement the skip_prologue gdbarch method.  */
+
+static CORE_ADDR
+or1k_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
+{
+  CORE_ADDR start_pc;
+  CORE_ADDR addr;
+  uint32_t inst;
+
+  unsigned int ra, rb, rd; /* for instruction analysis */
+  int simm;
+
+  int frame_size = 0;
+
+  /* Try using SAL first if we have symbolic information available.  This
+     only works for DWARF 2, not STABS.  */
+
+  if (find_pc_partial_function (pc, NULL, &start_pc, NULL))
+    {
+      CORE_ADDR prologue_end = skip_prologue_using_sal (gdbarch, pc);
+
+      if (0 != prologue_end)
+	{
+	  struct symtab_and_line prologue_sal = find_pc_line (start_pc, 0);
+	  struct compunit_symtab *compunit
+	    = SYMTAB_COMPUNIT (prologue_sal.symtab);
+	  const char *debug_format = COMPUNIT_DEBUGFORMAT (compunit);
+
+	  if ((NULL != debug_format)
+	      && (strlen ("dwarf") <= strlen (debug_format))
+	      && (0 == strncasecmp ("dwarf", debug_format, strlen ("dwarf"))))
+	    return (prologue_end > pc) ? prologue_end : pc;
+	}
+    }
+
+  /* Look to see if we can find any of the standard prologue sequence.  All
+     quite difficult, since any or all of it may be missing.  So this is
+     just a best guess!  */
+
+  addr = pc; /* Where we have got to */
+  inst = or1k_fetch_instruction (gdbarch, addr);
+
+  /* Look for the new stack pointer being set up.  */
+  if (or1k_analyse_l_addi (inst, &rd, &ra, &simm)
+      && (OR1K_SP_REGNUM == rd) && (OR1K_SP_REGNUM == ra)
+      && (simm < 0) && (0 == (simm % 4)))
+    {
+      frame_size = -simm;
+      addr += OR1K_INSTLEN;
+      inst = or1k_fetch_instruction (gdbarch, addr);
+    }
+
+  /* Look for the frame pointer being manipulated.  */
+  if (or1k_analyse_l_sw (inst, &simm, &ra, &rb)
+      && (OR1K_SP_REGNUM == ra) && (OR1K_FP_REGNUM == rb)
+      && (simm >= 0) && (0 == (simm % 4)))
+    {
+      addr += OR1K_INSTLEN;
+      inst = or1k_fetch_instruction (gdbarch, addr);
+
+      gdb_assert (or1k_analyse_l_addi (inst, &rd, &ra, &simm)
+		  && (OR1K_FP_REGNUM == rd) && (OR1K_SP_REGNUM == ra)
+		  && (simm == frame_size));
+
+      addr += OR1K_INSTLEN;
+      inst = or1k_fetch_instruction (gdbarch, addr);
+    }
+
+  /* Look for the link register being saved.  */
+  if (or1k_analyse_l_sw (inst, &simm, &ra, &rb)
+      && (OR1K_SP_REGNUM == ra) && (OR1K_LR_REGNUM == rb)
+      && (simm >= 0) && (0 == (simm % 4)))
+    {
+      addr += OR1K_INSTLEN;
+      inst = or1k_fetch_instruction (gdbarch, addr);
+    }
+
+  /* Look for arguments or callee-saved register being saved.  The register
+     must be one of the arguments (r3-r8) or the 10 callee saved registers
+     (r10, r12, r14, r16, r18, r20, r22, r24, r26, r28, r30).  The base
+     register must be the FP (for the args) or the SP (for the callee_saved
+     registers).  */
+  while (1)
+    {
+      if (or1k_analyse_l_sw (inst, &simm, &ra, &rb)
+	  && (((OR1K_FP_REGNUM == ra) && or1k_is_arg_reg (rb))
+	      || ((OR1K_SP_REGNUM == ra) && or1k_is_callee_saved_reg (rb)))
+	  && (0 == (simm % 4)))
+	{
+	  addr += OR1K_INSTLEN;
+	  inst = or1k_fetch_instruction (gdbarch, addr);
+	}
+      else
+	{
+	  /* Nothing else to look for.  We have found the end of the
+	     prologue.  */
+	  break;
+	}
+    }
+  return addr;
+}
+
+/* Implement the frame_align gdbarch method.  */
+
+static CORE_ADDR
+or1k_frame_align (struct gdbarch *gdbarch, CORE_ADDR sp)
+{
+  return align_down (sp, OR1K_STACK_ALIGN);
+}
+
+/* Implement the unwind_pc gdbarch method.  */
+
+static CORE_ADDR
+or1k_unwind_pc (struct gdbarch *gdbarch, struct frame_info *next_frame)
+{
+  CORE_ADDR pc;
+
+  if (or1k_debug)
+    fprintf_unfiltered (gdb_stdlog, "or1k_unwind_pc, next_frame=%d\n",
+			frame_relative_level (next_frame));
+
+  pc = frame_unwind_register_unsigned (next_frame, OR1K_NPC_REGNUM);
+
+  if (or1k_debug)
+    fprintf_unfiltered (gdb_stdlog, "or1k_unwind_pc, pc=0x%p\n",
+			(void *) pc);
+
+  return pc;
+}
+
+/* Implement the unwind_sp gdbarch method.  */
+
+static CORE_ADDR
+or1k_unwind_sp (struct gdbarch *gdbarch, struct frame_info *next_frame)
+{
+  CORE_ADDR sp;
+
+  if (or1k_debug)
+    fprintf_unfiltered (gdb_stdlog, "or1k_unwind_sp, next_frame=%d\n",
+			frame_relative_level (next_frame));
+
+  sp = frame_unwind_register_unsigned (next_frame, OR1K_SP_REGNUM);
+
+  if (or1k_debug)
+    fprintf_unfiltered (gdb_stdlog, "or1k_unwind_sp, sp=0x%p\n",
+			(void *) sp);
+
+  return sp;
+}
+
+/* Implement the push_dummy_code gdbarch method.  */
+
+static CORE_ADDR
+or1k_push_dummy_code (struct gdbarch *gdbarch, CORE_ADDR sp,
+		      CORE_ADDR function, struct value **args, int nargs,
+		      struct type *value_type, CORE_ADDR * real_pc,
+		      CORE_ADDR * bp_addr, struct regcache *regcache)
+{
+  CORE_ADDR bp_slot;
+
+  /* Reserve enough room on the stack for our breakpoint instruction.  */
+  bp_slot = sp - 4;
+  /* Store the address of that breakpoint.  */
+  *bp_addr = bp_slot;
+  /* keeping the stack aligned.  */
+  sp = or1k_frame_align (gdbarch, bp_slot);
+  /* The call starts at the callee's entry point.  */
+  *real_pc = function;
+
+  return sp;
+}
+
+/* Implement the push_dummy_call gdbarch method.  */
+
+static CORE_ADDR
+or1k_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;
+  int argnum;
+  int first_stack_arg;
+  int stack_offset = 0;
+  int heap_offset = 0;
+  CORE_ADDR heap_sp = sp - 128;
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  int bpa = (gdbarch_tdep (gdbarch))->bytes_per_address;
+  int bpw = (gdbarch_tdep (gdbarch))->bytes_per_word;
+  struct type *func_type = value_type (function);
+
+  /* Return address */
+  regcache_cooked_write_unsigned (regcache, OR1K_LR_REGNUM, bp_addr);
+
+  /* Register for the next argument.  */
+  argreg = OR1K_FIRST_ARG_REGNUM;
+
+  /* Location for a returned structure.  This is passed as a silent first
+     argument.  */
+  if (struct_return)
+    {
+      regcache_cooked_write_unsigned (regcache, OR1K_FIRST_ARG_REGNUM,
+				      struct_addr);
+      argreg++;
+    }
+
+  /* Put as many args as possible in registers.  */
+  for (argnum = 0; argnum < nargs; argnum++)
+    {
+      const gdb_byte *val;
+      gdb_byte valbuf[sizeof (ULONGEST)];
+
+      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);
+
+      if (TYPE_VARARGS (func_type) && argnum >= TYPE_NFIELDS (func_type))
+	break; /* end or regular args, varargs go to stack.  */
+
+      /* Extract the value, either a reference or the data.  */
+      if ((TYPE_CODE_STRUCT == typecode) || (TYPE_CODE_UNION == typecode)
+	  || (len > bpw * 2))
+	{
+	  CORE_ADDR valaddr = value_address (arg);
+
+	  /* If the arg is fabricated (i.e. 3*i, instead of i) valaddr is
+	     undefined.  */
+	  if (valaddr == 0)
+	    {
+	      /* The argument needs to be copied into the target space.
+		 Since the bottom of the stack is reserved for function
+		 arguments we store this at the these at the top growing
+		 down.  */
+	      heap_offset += align_up (len, bpw);
+	      valaddr = heap_sp + heap_offset;
+
+	      write_memory (valaddr, value_contents (arg), len);
+	    }
+
+	  /* The ABI passes all structures by reference, so get its
+	     address.  */
+	  store_unsigned_integer (valbuf, bpa, byte_order, valaddr);
+	  len = bpa;
+	  val = valbuf;
+	}
+      else
+	{
+	  /* Everything else, we just get the value.  */
+	  val = value_contents (arg);
+	}
+
+      /* Stick the value in a register.  */
+      if (len > bpw)
+	{
+	  /* Big scalars use two registers, but need NOT be pair aligned.  */
+
+	  if (argreg <= (OR1K_LAST_ARG_REGNUM - 1))
+	    {
+	      ULONGEST regval =	extract_unsigned_integer (val, len,
+							  byte_order);
+
+	      unsigned int bits_per_word = bpw * 8;
+	      ULONGEST mask = (((ULONGEST) 1) << bits_per_word) - 1;
+	      ULONGEST lo = regval & mask;
+	      ULONGEST hi = regval >> bits_per_word;
+
+	      regcache_cooked_write_unsigned (regcache, argreg, hi);
+	      regcache_cooked_write_unsigned (regcache, argreg + 1, lo);
+	      argreg += 2;
+	    }
+	  else
+	    {
+	      /* Run out of regs */
+	      break;
+	    }
+	}
+      else if (argreg <= OR1K_LAST_ARG_REGNUM)
+	{
+	  /* Smaller scalars fit in a single register.  */
+	  regcache_cooked_write_unsigned
+	    (regcache, argreg, extract_unsigned_integer (val, len,
+							 byte_order));
+	  argreg++;
+	}
+      else
+	{
+	  /* Ran out of regs.  */
+	  break;
+	}
+    }
+
+  first_stack_arg = argnum;
+
+  /* If we get here with argnum < nargs, then arguments remain to be
+     placed on the stack.  This is tricky, since they must be pushed in
+     reverse order and the stack in the end must be aligned.  The only
+     solution is to do it in two stages, the first to compute the stack
+     size, the second to save the args.  */
+
+  for (argnum = first_stack_arg; argnum < nargs; argnum++)
+    {
+      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);
+
+      if ((TYPE_CODE_STRUCT == typecode) || (TYPE_CODE_UNION == typecode)
+	  || (len > bpw * 2))
+	{
+	  /* Structures are passed as addresses.  */
+	  sp -= bpa;
+	}
+      else
+	{
+	  /* Big scalars use more than one word.  Code here allows for
+	     future quad-word entities (e.g. long double.)  */
+	  sp -= align_up (len, bpw);
+	}
+
+      /* Ensure our dummy heap doesn't touch the stack, this could only
+	 happen if we have many arguments including fabricated arguments.  */
+      gdb_assert (heap_offset == 0 || ((heap_sp + heap_offset) < sp));
+    }
+
+  sp = gdbarch_frame_align (gdbarch, sp);
+  stack_offset = 0;
+
+  /* Push the remaining args on the stack.  */
+  for (argnum = first_stack_arg; argnum < nargs; argnum++)
+    {
+      const gdb_byte *val;
+      gdb_byte valbuf[sizeof (ULONGEST)];
+
+      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);
+      /* The EABI passes structures that do not fit in a register by
+         reference.  In all other cases, pass the structure by value.  */
+      if ((TYPE_CODE_STRUCT == typecode) || (TYPE_CODE_UNION == typecode)
+	  || (len > bpw * 2))
+	{
+	  store_unsigned_integer (valbuf, bpa, byte_order,
+				  value_address (arg));
+	  len = bpa;
+	  val = valbuf;
+	}
+      else
+	val = value_contents (arg);
+
+      while (len > 0)
+	{
+	  int partial_len = (len < bpw ? len : bpw);
+
+	  write_memory (sp + stack_offset, val, partial_len);
+	  stack_offset += align_up (partial_len, bpw);
+	  len -= partial_len;
+	  val += partial_len;
+	}
+    }
+
+  /* Save the updated stack pointer.  */
+  regcache_cooked_write_unsigned (regcache, OR1K_SP_REGNUM, sp);
+
+  if (heap_offset > 0)
+    sp = heap_sp;
+
+  return sp;
+}
+
+/* Implement the dummy_id gdbarch method.  */
+
+static struct frame_id
+or1k_dummy_id (struct gdbarch *gdbarch, struct frame_info *this_frame)
+{
+  return frame_id_build (get_frame_sp (this_frame),
+			 get_frame_pc (this_frame));
+}
+
+
+/* Support functions for frame handling.  */
+
+/* Initialize a prologue cache
+
+   We build a cache, saying where registers of the prev frame can be found
+   from the data so far set up in this this.
+
+   We also compute a unique ID for this frame, based on the function start
+   address and the stack pointer (as it will be, even if it has yet to be
+   computed.
+
+   STACK FORMAT
+   ============
+
+   The OR1K has a falling stack frame and a simple prolog.  The Stack
+   pointer is R1 and the frame pointer R2.  The frame base is therefore the
+   address held in R2 and the stack pointer (R1) is the frame base of the
+   next frame.
+
+   l.addi  r1,r1,-frame_size	# SP now points to end of new stack frame
+
+   The stack pointer may not be set up in a frameless function (e.g. a
+   simple leaf function).
+
+   l.sw    fp_loc(r1),r2        # old FP saved in new stack frame
+   l.addi  r2,r1,frame_size     # FP now points to base of new stack frame
+
+   The frame pointer is not necessarily saved right at the end of the stack
+   frame - OR1K saves enough space for any args to called functions right
+   at the end (this is a difference from the Architecture Manual).
+
+   l.sw    lr_loc(r1),r9        # Link (return) address
+
+   The link register is usally saved at fp_loc - 4.  It may not be saved at
+   all in a leaf function.
+
+   l.sw    reg_loc(r1),ry       # Save any callee saved regs
+
+   The offsets x for the callee saved registers generally (always?) rise in
+   increments of 4, starting at fp_loc + 4.  If the frame pointer is
+   omitted (an option to GCC), then it may not be saved at all.  There may
+   be no callee saved registers.
+
+   So in summary none of this may be present.  However what is present
+   seems always to follow this fixed order, and occur before any
+   substantive code (it is possible for GCC to have more flexible
+   scheduling of the prologue, but this does not seem to occur for OR1K).
+
+   ANALYSIS
+   ========
+
+   This prolog is used, even for -O3 with GCC.
+
+   All this analysis must allow for the possibility that the PC is in the
+   middle of the prologue.  Data in the cache should only be set up insofar
+   as it has been computed.
+
+   HOWEVER.  The frame_id must be created with the SP *as it will be* at
+   the end of the Prologue.  Otherwise a recursive call, checking the frame
+   with the PC at the start address will end up with the same frame_id as
+   the caller.
+
+   A suite of "helper" routines are used, allowing reuse for
+   or1k_skip_prologue().
+
+   Reportedly, this is only valid for frames less than 0x7fff in size.  */
+
+static struct trad_frame_cache *
+or1k_frame_cache (struct frame_info *this_frame, void **prologue_cache)
+{
+  struct gdbarch *gdbarch;
+  struct trad_frame_cache *info;
+
+  CORE_ADDR this_pc;
+  CORE_ADDR this_sp;
+  CORE_ADDR this_sp_for_id;
+  int frame_size = 0;
+
+  CORE_ADDR start_addr;
+  CORE_ADDR end_addr;
+
+  if (or1k_debug)
+    fprintf_unfiltered (gdb_stdlog,
+			"or1k_frame_cache, prologue_cache = 0x%p\n",
+			*prologue_cache);
+
+  /* Nothing to do if we already have this info.  */
+  if (NULL != *prologue_cache)
+    return (struct trad_frame_cache *) *prologue_cache;
+
+  /* Get a new prologue cache and populate it with default values.  */
+  info = trad_frame_cache_zalloc (this_frame);
+  *prologue_cache = info;
+
+  /* Find the start address of this function (which is a normal frame, even
+     if the next frame is the sentinel frame) and the end of its prologue.  */
+  this_pc = get_frame_pc (this_frame);
+  find_pc_partial_function (this_pc, NULL, &start_addr, NULL);
+
+  /* Get the stack pointer if we have one (if there's no process executing
+     yet we won't have a frame.  */
+  this_sp = (NULL == this_frame) ? 0 :
+    get_frame_register_unsigned (this_frame, OR1K_SP_REGNUM);
+
+  /* Return early if GDB couldn't find the function.  */
+  if (start_addr == 0)
+    {
+      if (or1k_debug)
+	fprintf_unfiltered (gdb_stdlog, "  couldn't find function\n");
+
+      /* JPB: 28-Apr-11.  This is a temporary patch, to get round GDB
+	 crashing right at the beginning.  Build the frame ID as best we
+	 can.  */
+      trad_frame_set_id (info, frame_id_build (this_sp, this_pc));
+
+      return info;
+    }
+
+  /* The default frame base of this frame (for ID purposes only - frame
+     base is an overloaded term) is its stack pointer.  For now we use the
+     value of the SP register in this frame.  However if the PC is in the
+     prologue of this frame, before the SP has been set up, then the value
+     will actually be that of the prev frame, and we'll need to adjust it
+     later.  */
+  trad_frame_set_this_base (info, this_sp);
+  this_sp_for_id = this_sp;
+
+  /* The default is to find the PC of the previous frame in the link
+     register of this frame.  This may be changed if we find the link
+     register was saved on the stack.  */
+  trad_frame_set_reg_realreg (info, OR1K_NPC_REGNUM, OR1K_LR_REGNUM);
+
+  /* We should only examine code that is in the prologue.  This is all code
+     up to (but not including) end_addr.  We should only populate the cache
+     while the address is up to (but not including) the PC or end_addr,
+     whichever is first.  */
+  gdbarch = get_frame_arch (this_frame);
+  end_addr = or1k_skip_prologue (gdbarch, start_addr);
+
+  /* All the following analysis only occurs if we are in the prologue and
+     have executed the code.  Check we have a sane prologue size, and if
+     zero we are frameless and can give up here.  */
+  if (end_addr < start_addr)
+    error ("end addr 0x%08x is less than start addr 0x%08x\n",
+		(unsigned int) end_addr, (unsigned int) start_addr);
+
+  if (end_addr == start_addr)
+    frame_size = 0;
+  else
+    {
+      /* We have a frame.  Look for the various components.  */
+      CORE_ADDR addr = start_addr; /* Where we have got to */
+      uint32_t inst = or1k_fetch_instruction (gdbarch, addr);
+
+      unsigned int ra, rb, rd; /* for instruction analysis */
+      int simm;
+
+      /* Look for the new stack pointer being set up.  */
+      if (or1k_analyse_l_addi (inst, &rd, &ra, &simm)
+	  && (OR1K_SP_REGNUM == rd) && (OR1K_SP_REGNUM == ra)
+	  && (simm < 0) && (0 == (simm % 4)))
+	{
+	  frame_size = -simm;
+	  addr += OR1K_INSTLEN;
+	  inst = or1k_fetch_instruction (gdbarch, addr);
+
+	  /* If the PC has not actually got to this point, then the frame
+	     base will be wrong, and we adjust it.
+
+	     If we are past this point, then we need to populate the stack
+	     accordingly.  */
+	  if (this_pc <= addr)
+	    {
+	      /* Only do if executing.  */
+	      if (0 != this_sp)
+		{
+		  this_sp_for_id = this_sp + frame_size;
+		  trad_frame_set_this_base (info, this_sp_for_id);
+		}
+	    }
+	  else
+	    {
+	      /* We are past this point, so the stack pointer of the prev
+	         frame is frame_size greater than the stack pointer of this
+	         frame.  */
+	      trad_frame_set_reg_value (info, OR1K_SP_REGNUM,
+					this_sp + frame_size);
+	    }
+	}
+
+      /* From now on we are only populating the cache, so we stop once we
+	 get to either the end OR the current PC.  */
+      end_addr = (this_pc < end_addr) ? this_pc : end_addr;
+
+      /* Look for the frame pointer being manipulated.  */
+      if ((addr < end_addr)
+	  && or1k_analyse_l_sw (inst, &simm, &ra, &rb)
+	  && (OR1K_SP_REGNUM == ra) && (OR1K_FP_REGNUM == rb)
+	  && (simm >= 0) && (0 == (simm % 4)))
+	{
+	  addr += OR1K_INSTLEN;
+	  inst = or1k_fetch_instruction (gdbarch, addr);
+
+	  /* At this stage, we can find the frame pointer of the previous
+	     frame on the stack of the current frame.  */
+	  trad_frame_set_reg_addr (info, OR1K_FP_REGNUM, this_sp + simm);
+
+	  /* Look for the new frame pointer being set up.  */
+	  if ((addr < end_addr)
+	      && or1k_analyse_l_addi (inst, &rd, &ra, &simm)
+	      && (OR1K_FP_REGNUM == rd) && (OR1K_SP_REGNUM == ra)
+	      && (simm == frame_size))
+	    {
+	      addr += OR1K_INSTLEN;
+	      inst = or1k_fetch_instruction (gdbarch, addr);
+
+	      /* If we have got this far, the stack pointer of the previous
+	         frame is the frame pointer of this frame.  */
+	      trad_frame_set_reg_realreg (info, OR1K_SP_REGNUM,
+					  OR1K_FP_REGNUM);
+	    }
+	}
+
+      /* Look for the link register being saved.  */
+      if ((addr < end_addr)
+	  && or1k_analyse_l_sw (inst, &simm, &ra, &rb)
+	  && (OR1K_SP_REGNUM == ra) && (OR1K_LR_REGNUM == rb)
+	  && (simm >= 0) && (0 == (simm % 4)))
+	{
+	  addr += OR1K_INSTLEN;
+	  inst = or1k_fetch_instruction (gdbarch, addr);
+
+	  /* If the link register is saved in the this frame, it holds the
+	     value of the PC in the previous frame.  This overwrites the
+	     previous information about finding the PC in the link
+	     register.  */
+	  trad_frame_set_reg_addr (info, OR1K_NPC_REGNUM, this_sp + simm);
+	}
+
+      /* Look for arguments or callee-saved register being saved.  The
+	 register must be one of the arguments (r3-r8) or the 10 callee
+	 saved registers (r10, r12, r14, r16, r18, r20, r22, r24, r26, r28,
+	 r30).  The base register must be the FP (for the args) or the SP
+	 (for the callee_saved registers).  */
+      while (addr < end_addr)
+	{
+	  if (or1k_analyse_l_sw (inst, &simm, &ra, &rb)
+	      && (((OR1K_FP_REGNUM == ra) && or1k_is_arg_reg (rb))
+		  || ((OR1K_SP_REGNUM == ra)
+		      && or1k_is_callee_saved_reg (rb)))
+	      && (0 == (simm % 4)))
+	    {
+	      addr += OR1K_INSTLEN;
+	      inst = or1k_fetch_instruction (gdbarch, addr);
+
+	      /* The register in the previous frame can be found at this
+	         location in this frame.  */
+	      trad_frame_set_reg_addr (info, rb, this_sp + simm);
+	    }
+	  else
+	    break; /* Not a register save instruction.  */
+	}
+    }
+
+  /* Build the frame ID */
+  trad_frame_set_id (info, frame_id_build (this_sp_for_id, start_addr));
+
+  if (or1k_debug)
+    {
+      fprintf_unfiltered (gdb_stdlog, "  this_sp_for_id = 0x%p\n",
+			  (void *) this_sp_for_id);
+      fprintf_unfiltered (gdb_stdlog, "  start_addr     = 0x%p\n",
+			  (void *) start_addr);
+    }
+
+  return info;
+}
+
+/* Implement the this_id function for the stub unwinder.  */
+
+static void
+or1k_frame_this_id (struct frame_info *this_frame,
+		    void **prologue_cache, struct frame_id *this_id)
+{
+  struct trad_frame_cache *info = or1k_frame_cache (this_frame,
+						    prologue_cache);
+
+  trad_frame_get_id (info, this_id);
+}
+
+/* Implement the prev_register function for the stub unwinder.  */
+
+static struct value *
+or1k_frame_prev_register (struct frame_info *this_frame,
+			  void **prologue_cache, int regnum)
+{
+  struct trad_frame_cache *info = or1k_frame_cache (this_frame,
+						    prologue_cache);
+
+  return trad_frame_get_register (info, this_frame, regnum);
+}
+
+/* Data structures for the normal prologue-analysis-based unwinder.  */
+
+static const struct frame_unwind or1k_frame_unwind = {
+  NORMAL_FRAME,
+  default_frame_unwind_stop_reason,
+  or1k_frame_this_id,
+  or1k_frame_prev_register,
+  NULL,
+  default_frame_sniffer,
+  NULL,
+};
+
+/* Architecture initialization for OpenRISC 1000.  */
+
+static struct gdbarch *
+or1k_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
+{
+  struct gdbarch *gdbarch;
+  struct gdbarch_tdep *tdep;
+  const struct bfd_arch_info *binfo;
+  struct tdesc_arch_data *tdesc_data = NULL;
+  const struct target_desc *tdesc = info.target_desc;
+
+  /* Find a candidate among the list of pre-declared architectures.  */
+  arches = gdbarch_list_lookup_by_info (arches, &info);
+  if (NULL != arches)
+    return arches->gdbarch;
+
+  /* None found, create a new architecture from the information
+     provided.  Can't initialize all the target dependencies until we
+     actually know which target we are talking to, but put in some defaults
+     for now.  */
+  binfo = info.bfd_arch_info;
+  tdep = XCNEW (struct gdbarch_tdep);
+  tdep->bytes_per_word = binfo->bits_per_word / binfo->bits_per_byte;
+  tdep->bytes_per_address = binfo->bits_per_address / binfo->bits_per_byte;
+  gdbarch = gdbarch_alloc (&info, tdep);
+
+  /* Target data types */
+  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_float_format (gdbarch, floatformats_ieee_single);
+  set_gdbarch_double_bit (gdbarch, 64);
+  set_gdbarch_double_format (gdbarch, floatformats_ieee_double);
+  set_gdbarch_long_double_bit (gdbarch, 64);
+  set_gdbarch_long_double_format (gdbarch, floatformats_ieee_double);
+  set_gdbarch_ptr_bit (gdbarch, binfo->bits_per_address);
+  set_gdbarch_addr_bit (gdbarch, binfo->bits_per_address);
+  set_gdbarch_char_signed (gdbarch, 1);
+
+  /* Information about the target architecture */
+  set_gdbarch_return_value (gdbarch, or1k_return_value);
+  set_gdbarch_breakpoint_kind_from_pc (gdbarch,
+				       or1k_breakpoint::kind_from_pc);
+  set_gdbarch_sw_breakpoint_from_kind (gdbarch,
+				       or1k_breakpoint::bp_from_kind);
+  set_gdbarch_have_nonsteppable_watchpoint (gdbarch, 1);
+
+  /* Register architecture */
+  set_gdbarch_num_regs (gdbarch, OR1K_NUM_REGS);
+  set_gdbarch_num_pseudo_regs (gdbarch, OR1K_NUM_PSEUDO_REGS);
+  set_gdbarch_sp_regnum (gdbarch, OR1K_SP_REGNUM);
+  set_gdbarch_pc_regnum (gdbarch, OR1K_NPC_REGNUM);
+  set_gdbarch_ps_regnum (gdbarch, OR1K_SR_REGNUM);
+  set_gdbarch_deprecated_fp_regnum (gdbarch, OR1K_FP_REGNUM);
+
+  /* Functions to analyse frames */
+  set_gdbarch_skip_prologue (gdbarch, or1k_skip_prologue);
+  set_gdbarch_inner_than (gdbarch, core_addr_lessthan);
+  set_gdbarch_frame_align (gdbarch, or1k_frame_align);
+  set_gdbarch_frame_red_zone_size (gdbarch, OR1K_FRAME_RED_ZONE_SIZE);
+
+  /* Functions to access frame data */
+  set_gdbarch_unwind_pc (gdbarch, or1k_unwind_pc);
+  set_gdbarch_unwind_sp (gdbarch, or1k_unwind_sp);
+
+  /* Functions handling dummy frames */
+  set_gdbarch_call_dummy_location (gdbarch, ON_STACK);
+  set_gdbarch_push_dummy_code (gdbarch, or1k_push_dummy_code);
+  set_gdbarch_push_dummy_call (gdbarch, or1k_push_dummy_call);
+  set_gdbarch_dummy_id (gdbarch, or1k_dummy_id);
+
+  /* Frame unwinders.  Use DWARF debug info if available, otherwise use our
+     own unwinder.  */
+  dwarf2_append_unwinders (gdbarch);
+  frame_unwind_append_unwinder (gdbarch, &or1k_frame_unwind);
+
+  /* Get a CGEN CPU descriptor for this architecture.  */
+  {
+
+    const char *mach_name = binfo->printable_name;
+    enum cgen_endian endian = (info.byte_order == BFD_ENDIAN_BIG
+			       ? CGEN_ENDIAN_BIG : CGEN_ENDIAN_LITTLE);
+
+    tdep->gdb_cgen_cpu_desc =
+      or1k_cgen_cpu_open (CGEN_CPU_OPEN_BFDMACH, mach_name,
+			  CGEN_CPU_OPEN_ENDIAN, endian, CGEN_CPU_OPEN_END);
+
+    or1k_cgen_init_asm (tdep->gdb_cgen_cpu_desc);
+  }
+
+  /* If this mach has a delay slot.  */
+  if (binfo->mach == bfd_mach_or1k)
+    set_gdbarch_single_step_through_delay (gdbarch,
+					   or1k_single_step_through_delay);
+
+  if (!tdesc_has_registers (info.target_desc))
+    /* Pick a default target description.  */
+    tdesc = tdesc_or1k;
+
+  /* Check any target description for validity.  */
+  if (tdesc_has_registers (tdesc))
+    {
+      const struct tdesc_feature *feature;
+      int valid_p;
+      int i;
+
+      feature = tdesc_find_feature (tdesc, "org.gnu.gdb.or1k.group0");
+      if (feature == NULL)
+        return NULL;
+
+      tdesc_data = tdesc_data_alloc ();
+
+      valid_p = 1;
+
+      for (i = 0; i < OR1K_NUM_REGS; i++)
+        valid_p &= tdesc_numbered_register (feature, tdesc_data, i,
+                                            or1k_reg_names[i]);
+
+      if (!valid_p)
+        {
+          tdesc_data_cleanup (tdesc_data);
+          return NULL;
+        }
+    }
+
+  if (tdesc_data != NULL)
+    {
+      /* If we are using tdesc, register our own reggroups, otherwise we
+	 will used the defaults.  */
+      reggroup_add (gdbarch, general_reggroup);
+      reggroup_add (gdbarch, system_reggroup);
+      reggroup_add (gdbarch, float_reggroup);
+      reggroup_add (gdbarch, vector_reggroup);
+      reggroup_add (gdbarch, all_reggroup);
+      reggroup_add (gdbarch, save_reggroup);
+      reggroup_add (gdbarch, restore_reggroup);
+
+      tdesc_use_registers (gdbarch, tdesc, tdesc_data);
+    }
+
+  return gdbarch;
+}
+
+/* Dump the target specific data for this architecture.  */
+
+static void
+or1k_dump_tdep (struct gdbarch *gdbarch, struct ui_file *file)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
+  if (NULL == tdep)
+    return; /* Nothing to report */
+
+  fprintf_unfiltered (file, "or1k_dump_tdep: %d bytes per word\n",
+		      tdep->bytes_per_word);
+  fprintf_unfiltered (file, "or1k_dump_tdep: %d bytes per address\n",
+		      tdep->bytes_per_address);
+}
+
+
+void
+_initialize_or1k_tdep (void)
+{
+  /* Register this architecture.  */
+  gdbarch_register (bfd_arch_or1k, or1k_gdbarch_init, or1k_dump_tdep);
+
+  initialize_tdesc_or1k ();
+
+  /* Debugging flag.  */
+  add_setshow_boolean_cmd ("or1k", class_maintenance, &or1k_debug,
+			   _("Set OpenRISC debugging."),
+			   _("Show OpenRISC debugging."),
+			   _("When on, OpenRISC specific debugging is enabled."),
+			   NULL,
+			   show_or1k_debug,
+			   &setdebuglist, &showdebuglist);
+}