[RFC] Add support for Renesas RX architecture

Kevin Buettner kevinb@redhat.com
Thu Dec 3 23:19:00 GMT 2009


The patch below adds support for the Renesas RX architecture to GDB.

I'll note up front that there's one #if 0 in rx-tdep.c.  I'd prefer to
leave it there until Nick and I get all of the kinks worked out of
the debug info.  I'm willing to remove it though if there are objections
to having it in new code.

Comments?

	* configure.tgt: Add rx-*-elf target.
	* rx-tdep.c: New target.

Index: configure.tgt
===================================================================
RCS file: /cvs/src/src/gdb/configure.tgt,v
retrieving revision 1.227
diff -u -p -r1.227 configure.tgt
--- configure.tgt	21 Oct 2009 14:14:56 -0000	1.227
+++ configure.tgt	3 Dec 2009 23:06:55 -0000
@@ -408,6 +408,12 @@ s390*-*-*)
 	build_gdbserver=yes
 	;;
 
+rx-*-elf)
+	# Target: Renesas RX
+	gdb_target_obs="rx-tdep.o"
+	gdb_sim=../sim/rx/libsim.a
+	;;
+
 score-*-*)
 	# Target: S+core embedded system
 	gdb_target_obs="score-tdep.o corelow.o"
Index: rx-tdep.c
===================================================================
RCS file: rx-tdep.c
diff -N rx-tdep.c
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ rx-tdep.c	3 Dec 2009 23:06:55 -0000
@@ -0,0 +1,864 @@
+/* Target-dependent code for the Renesas RX for GDB, the GNU debugger.
+
+   Copyright (C) 2008, 2009
+   Free Software Foundation, Inc.
+
+   Contributed by Red Hat, 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 "arch-utils.h"
+#include "prologue-value.h"
+#include "target.h"
+#include "regcache.h"
+#include "opcode/rx.h"
+#include "dis-asm.h"
+#include "gdbtypes.h"
+#include "frame.h"
+#include "frame-unwind.h"
+#include "frame-base.h"
+#include "value.h"
+#include "gdbcore.h"
+#include "dwarf2-frame.h"
+
+#include "elf/rx.h"
+#include "elf-bfd.h"
+
+/* Certain important register numbers.  */
+enum
+{
+  RX_SP_REGNUM = 0,
+  RX_R1_REGNUM = 1,
+  RX_R4_REGNUM = 4,
+  RX_FP_REGNUM = 6,
+  RX_R15_REGNUM = 15,
+  RX_PC_REGNUM = 19,
+  RX_NUM_REGS = 25
+};
+
+/* Architecture specific data.  */
+struct gdbarch_tdep
+{
+  /* The ELF header flags specify the multilib used.  */
+  int elf_flags;
+};
+
+/* This structure holds the results of a prologue analysis.  */
+struct rx_prologue
+{
+  /* The offset from the frame base to the stack pointer --- always
+     zero or negative.
+
+     Calling this a "size" is a bit misleading, but given that the
+     stack grows downwards, using offsets for everything keeps one
+     from going completely sign-crazy: you never change anything's
+     sign for an ADD instruction; always change the second operand's
+     sign for a SUB instruction; and everything takes care of
+     itself.  */
+  int frame_size;
+
+  /* Non-zero if this function has initialized the frame pointer from
+     the stack pointer, zero otherwise.  */
+  int has_frame_ptr;
+
+  /* If has_frame_ptr is non-zero, this is the offset from the frame
+     base to where the frame pointer points.  This is always zero or
+     negative.  */
+  int frame_ptr_offset;
+
+  /* The address of the first instruction at which the frame has been
+     set up and the arguments are where the debug info says they are
+     --- as best as we can tell.  */
+  CORE_ADDR prologue_end;
+
+  /* reg_offset[R] is the offset from the CFA at which register R is
+     saved, or 1 if register R has not been saved.  (Real values are
+     always zero or negative.)  */
+  int reg_offset[RX_NUM_REGS];
+};
+
+/* Implement the "register_name" gdbarch method.  */
+static const char *
+rx_register_name (struct gdbarch *gdbarch, int regnr)
+{
+  static const char *const reg_names[] = {
+    "r0",
+    "r1",
+    "r2",
+    "r3",
+    "r4",
+    "r5",
+    "r6",
+    "r7",
+    "r8",
+    "r9",
+    "r10",
+    "r11",
+    "r12",
+    "r13",
+    "r14",
+    "r15",
+    "isp",
+    "usp",
+    "intb",
+    "pc",
+    "psw",
+    "bpc",
+    "bpsw",
+    "vct",
+    "fpsw"
+  };
+
+  return reg_names[regnr];
+}
+
+/* Implement the "register_type" gdbarch method.  */
+static struct type *
+rx_register_type (struct gdbarch *gdbarch, int reg_nr)
+{
+  if (reg_nr == RX_PC_REGNUM)
+    return builtin_type (gdbarch)->builtin_func_ptr;
+  else
+    return builtin_type (gdbarch)->builtin_unsigned_long;
+}
+
+
+/* Function for finding saved registers in a 'struct pv_area'; this
+   function is passed to pv_area_scan.
+
+   If VALUE is a saved register, ADDR says it was saved at a constant
+   offset from the frame base, and SIZE indicates that the whole
+   register was saved, record its offset.  */
+static void
+check_for_saved (void *result_untyped, pv_t addr, CORE_ADDR size, pv_t value)
+{
+  struct rx_prologue *result = (struct rx_prologue *) result_untyped;
+
+  if (value.kind == pvk_register
+      && value.k == 0
+      && pv_is_register (addr, RX_SP_REGNUM)
+      && size == register_size (target_gdbarch, value.reg))
+    result->reg_offset[value.reg] = addr.k;
+}
+
+/* Define a "handle" struct for fetching the next opcode.  */
+struct rx_get_opcode_byte_handle
+{
+  CORE_ADDR pc;
+};
+
+/* Fetch a byte on behalf of the opcode decoder.  HANDLE contains
+   the memory address of the next byte to fetch.  If successful,
+   the address in the handle is updated and the byte fetched is
+   returned as the value of the function.  If not successful, -1
+   is returned.  */
+static int
+rx_get_opcode_byte (void *handle)
+{
+  struct rx_get_opcode_byte_handle *opcdata = handle;
+  int status;
+  gdb_byte byte;
+
+  status = target_read_memory (opcdata->pc, &byte, 1);
+  if (status == 0)
+    {
+      opcdata->pc += 1;
+      return byte;
+    }
+  else
+    return -1;
+}
+
+/* Analyze a prologue starting at START_PC, going no further than
+   LIMIT_PC.  Fill in RESULT as appropriate.  */
+static void
+rx_analyze_prologue (CORE_ADDR start_pc,
+		     CORE_ADDR limit_pc, struct rx_prologue *result)
+{
+  CORE_ADDR pc, next_pc;
+  int rn;
+  pv_t reg[RX_NUM_REGS];
+  struct pv_area *stack;
+  struct cleanup *back_to;
+  CORE_ADDR after_last_frame_setup_insn = start_pc;
+
+  memset (result, 0, sizeof (*result));
+
+  for (rn = 0; rn < RX_NUM_REGS; rn++)
+    {
+      reg[rn] = pv_register (rn, 0);
+      result->reg_offset[rn] = 1;
+    }
+
+  stack = make_pv_area (RX_SP_REGNUM, gdbarch_addr_bit (target_gdbarch));
+  back_to = make_cleanup_free_pv_area (stack);
+
+  /* The call instruction has saved the return address on the stack.  */
+  reg[RX_SP_REGNUM] = pv_add_constant (reg[RX_SP_REGNUM], -4);
+  pv_area_store (stack, reg[RX_SP_REGNUM], 4, reg[RX_PC_REGNUM]);
+
+  pc = start_pc;
+  while (pc < limit_pc)
+    {
+      int bytes_read;
+      struct rx_get_opcode_byte_handle opcode_handle;
+      RX_Opcode_Decoded opc;
+
+      opcode_handle.pc = pc;
+      bytes_read = rx_decode_opcode (pc, &opc, rx_get_opcode_byte,
+				     &opcode_handle);
+      next_pc = pc + bytes_read;
+
+      if (opc.id == RXO_pushm	/* pushm r1, r2 */
+	  && opc.op[1].type == RX_Operand_Register
+	  && opc.op[2].type == RX_Operand_Register)
+	{
+	  int r1, r2;
+	  int r;
+
+	  r1 = opc.op[1].reg;
+	  r2 = opc.op[2].reg;
+	  for (r = r2; r >= r1; r--)
+	    {
+	      reg[RX_SP_REGNUM] = pv_add_constant (reg[RX_SP_REGNUM], -4);
+	      pv_area_store (stack, reg[RX_SP_REGNUM], 4, reg[r]);
+	    }
+	  after_last_frame_setup_insn = next_pc;
+	}
+      else if (opc.id == RXO_mov	/* mov.l rdst, rsrc */
+	       && opc.op[0].type == RX_Operand_Register
+	       && opc.op[1].type == RX_Operand_Register
+	       && opc.size == RX_Long)
+	{
+	  int rdst, rsrc;
+
+	  rdst = opc.op[0].reg;
+	  rsrc = opc.op[1].reg;
+	  reg[rdst] = reg[rsrc];
+	  if (rdst == RX_FP_REGNUM && rsrc == RX_SP_REGNUM)
+	    after_last_frame_setup_insn = next_pc;
+	}
+      else if (opc.id == RXO_mov	/* mov.l rsrc, [-SP] */
+	       && opc.op[0].type == RX_Operand_Predec
+	       && opc.op[0].reg == RX_SP_REGNUM
+	       && opc.op[1].type == RX_Operand_Register
+	       && opc.size == RX_Long)
+	{
+	  int rsrc;
+
+	  rsrc = opc.op[1].reg;
+	  reg[RX_SP_REGNUM] = pv_add_constant (reg[RX_SP_REGNUM], -4);
+	  pv_area_store (stack, reg[RX_SP_REGNUM], 4, reg[rsrc]);
+	  after_last_frame_setup_insn = next_pc;
+	}
+      else if (opc.id == RXO_add	/* add #const, rsrc, rdst */
+	       && opc.op[0].type == RX_Operand_Register
+	       && opc.op[1].type == RX_Operand_Immediate
+	       && opc.op[2].type == RX_Operand_Register)
+	{
+	  int rdst = opc.op[0].reg;
+	  int addend = opc.op[1].addend;
+	  int rsrc = opc.op[2].reg;
+	  reg[rdst] = pv_add_constant (reg[rsrc], addend);
+	  /* Negative adjustments to the stack pointer or frame pointer
+	     are (most likely) part of the prologue.  */
+	  if ((rdst == RX_SP_REGNUM || rdst == RX_FP_REGNUM) && addend < 0)
+	    after_last_frame_setup_insn = next_pc;
+	}
+      else if (opc.id == RXO_mov
+	       && opc.op[0].type == RX_Operand_Indirect
+	       && opc.op[1].type == RX_Operand_Register
+	       && opc.size == RX_Long
+	       && (opc.op[0].reg == RX_SP_REGNUM
+		   || opc.op[0].reg == RX_FP_REGNUM)
+	       && (RX_R1_REGNUM <= opc.op[1].reg
+		   && opc.op[1].reg <= RX_R4_REGNUM))
+	{
+	  /* This moves an argument register to the stack.  Don't
+	     record it, but allow it to be a part of the prologue.  */
+	}
+      else if (opc.id == RXO_branch
+	       && opc.op[0].type == RX_Operand_Immediate
+	       && opc.op[1].type == RX_Operand_Condition
+	       && next_pc < opc.op[0].addend)
+	{
+	  /* When a loop appears as the first statement of a function
+	     body, gcc 4.x will use a BRA instruction to branch to the
+	     loop condition checking code.  This BRA instruction is
+	     marked as part of the prologue.  We therefore set next_pc
+	     to this branch target and also stop the prologue scan.
+	     The instructions at and beyond the branch target should
+	     no longer be associated with the prologue.
+
+	     Note that we only consider forward branches here.  We
+	     presume that a forward branch is being used to skip over
+	     a loop body.
+
+	     A backwards branch is covered by the default case below.
+	     If we were to encounter a backwards branch, that would
+	     most likely mean that we've scanned through a loop body.
+	     We definitely want to stop the prologue scan when this
+	     happens and that is precisely what is done by the default
+	     case below.  */
+
+	  after_last_frame_setup_insn = opc.op[0].addend;
+	  break;		/* Scan no further if we hit this case.  */
+	}
+      else
+	{
+	  /* Terminate the prologue scan.  */
+	  break;
+	}
+
+      pc = next_pc;
+    }
+
+  /* Is the frame size (offset, really) a known constant?  */
+  if (pv_is_register (reg[RX_SP_REGNUM], RX_SP_REGNUM))
+    result->frame_size = reg[RX_SP_REGNUM].k;
+
+  /* Was the frame pointer initialized?  */
+  if (pv_is_register (reg[RX_FP_REGNUM], RX_SP_REGNUM))
+    {
+      result->has_frame_ptr = 1;
+      result->frame_ptr_offset = reg[RX_FP_REGNUM].k;
+    }
+
+  /* Record where all the registers were saved.  */
+  pv_area_scan (stack, check_for_saved, (void *) result);
+
+  result->prologue_end = after_last_frame_setup_insn;
+
+  do_cleanups (back_to);
+}
+
+
+/* Implement the "skip_prologue" gdbarch method.  */
+static CORE_ADDR
+rx_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
+{
+  char *name;
+  CORE_ADDR func_addr, func_end;
+  struct rx_prologue p;
+
+  /* Try to find the extent of the function that contains PC.  */
+  if (!find_pc_partial_function (pc, &name, &func_addr, &func_end))
+    return pc;
+
+  rx_analyze_prologue (pc, func_end, &p);
+  return p.prologue_end;
+}
+
+/* Given a frame described by THIS_FRAME, decode the prologue of its
+   associated function if there is not cache entry as specified by
+   THIS_PROLOGUE_CACHE.  Save the decoded prologue in the cache and
+   return that struct as the value of this function.  */
+static struct rx_prologue *
+rx_analyze_frame_prologue (struct frame_info *this_frame,
+			   void **this_prologue_cache)
+{
+  if (!*this_prologue_cache)
+    {
+      CORE_ADDR func_start, stop_addr;
+
+      *this_prologue_cache = FRAME_OBSTACK_ZALLOC (struct rx_prologue);
+
+      func_start = get_frame_func (this_frame);
+      stop_addr = get_frame_pc (this_frame);
+
+      /* If we couldn't find any function containing the PC, then
+         just initialize the prologue cache, but don't do anything.  */
+      if (!func_start)
+	stop_addr = func_start;
+
+      rx_analyze_prologue (func_start, stop_addr, *this_prologue_cache);
+    }
+
+  return *this_prologue_cache;
+}
+
+/* Given the next frame and a prologue cache, return this frame's
+   base.  */
+static CORE_ADDR
+rx_frame_base (struct frame_info *this_frame, void **this_prologue_cache)
+{
+  struct rx_prologue *p
+    = rx_analyze_frame_prologue (this_frame, this_prologue_cache);
+
+  /* In functions that use alloca, the distance between the stack
+     pointer and the frame base varies dynamically, so we can't use
+     the SP plus static information like prologue analysis to find the
+     frame base.  However, such functions must have a frame pointer,
+     to be able to restore the SP on exit.  So whenever we do have a
+     frame pointer, use that to find the base.  */
+  if (p->has_frame_ptr)
+    {
+      CORE_ADDR fp = get_frame_register_unsigned (this_frame, RX_FP_REGNUM);
+      return fp - p->frame_ptr_offset;
+    }
+  else
+    {
+      CORE_ADDR sp = get_frame_register_unsigned (this_frame, RX_SP_REGNUM);
+      return sp - p->frame_size;
+    }
+}
+
+/* Implement the "frame_this_id" method for unwinding frames.  */
+static void
+rx_frame_this_id (struct frame_info *this_frame,
+		  void **this_prologue_cache, struct frame_id *this_id)
+{
+  *this_id = frame_id_build (rx_frame_base (this_frame, this_prologue_cache),
+			     get_frame_func (this_frame));
+}
+
+/* Implement the "frame_prev_register" method for unwinding frames.  */
+static struct value *
+rx_frame_prev_register (struct frame_info *this_frame,
+			void **this_prologue_cache, int regnum)
+{
+  struct rx_prologue *p
+    = rx_analyze_frame_prologue (this_frame, this_prologue_cache);
+  CORE_ADDR frame_base = rx_frame_base (this_frame, this_prologue_cache);
+  int reg_size = register_size (get_frame_arch (this_frame), regnum);
+
+  if (regnum == RX_SP_REGNUM)
+    return frame_unwind_got_constant (this_frame, regnum, frame_base);
+
+  /* If prologue analysis says we saved this register somewhere,
+     return a description of the stack slot holding it.  */
+  else if (p->reg_offset[regnum] != 1)
+    return frame_unwind_got_memory (this_frame, regnum,
+				    frame_base + p->reg_offset[regnum]);
+
+  /* Otherwise, presume we haven't changed the value of this
+     register, and get it from the next frame.  */
+  else
+    return frame_unwind_got_register (this_frame, regnum, regnum);
+}
+
+static const struct frame_unwind rx_frame_unwind = {
+  NORMAL_FRAME,
+  rx_frame_this_id,
+  rx_frame_prev_register,
+  NULL,
+  default_frame_sniffer
+};
+
+/* Implement the "unwind_pc" gdbarch method.  */
+static CORE_ADDR
+rx_unwind_pc (struct gdbarch *gdbarch, struct frame_info *this_frame)
+{
+  ULONGEST pc;
+
+  pc = frame_unwind_register_unsigned (this_frame, RX_PC_REGNUM);
+  return pc;
+}
+
+/* Implement the "unwind_sp" gdbarch method.  */
+static CORE_ADDR
+rx_unwind_sp (struct gdbarch *gdbarch, struct frame_info *this_frame)
+{
+  ULONGEST sp;
+
+  sp = frame_unwind_register_unsigned (this_frame, RX_SP_REGNUM);
+  return sp;
+}
+
+/* Implement the "dummy_id" gdbarch method.  */
+static struct frame_id
+rx_dummy_id (struct gdbarch *gdbarch, struct frame_info *this_frame)
+{
+  return
+    frame_id_build (get_frame_register_unsigned (this_frame, RX_SP_REGNUM),
+		    get_frame_pc (this_frame));
+}
+
+/* Implement the "push_dummy_call" gdbarch method.  */
+static CORE_ADDR
+rx_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)
+{
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  int write_pass;
+  int sp_off = 0;
+  CORE_ADDR cfa;
+  int num_register_candidate_args;
+
+  struct type *func_type = value_type (function);
+
+  /* Dereference function pointer types.  */
+  while (TYPE_CODE (func_type) == TYPE_CODE_PTR)
+    func_type = TYPE_TARGET_TYPE (func_type);
+
+  /* The end result had better be a function or a method.  */
+  gdb_assert (TYPE_CODE (func_type) == TYPE_CODE_FUNC
+	      || TYPE_CODE (func_type) == TYPE_CODE_METHOD);
+
+  /* Functions with a variable number of arguments have all of their
+     variable arguments and the last non-variable argument passed
+     on the stack.
+
+     Otherwise, we can pass up to four arguments on the stack.
+
+     Once computed, we leave this value alone.  I.e. we don't update
+     it in case of a struct return going in a register or an argument
+     requiring multiple registers, etc.  We rely instead on the value
+     of the ``arg_reg'' variable to get these other details correct.  */
+
+  if (TYPE_VARARGS (func_type))
+    num_register_candidate_args = TYPE_NFIELDS (func_type) - 1;
+  else
+    num_register_candidate_args = 4;
+
+  /* We make two passes; the first does the stack allocation,
+     the second actually stores the arguments.  */
+  for (write_pass = 0; write_pass <= 1; write_pass++)
+    {
+      int i;
+      int arg_reg = RX_R1_REGNUM;
+
+      if (write_pass)
+	sp = align_down (sp - sp_off, 4);
+      sp_off = 0;
+
+      if (struct_return)
+	{
+	  struct type *return_type = TYPE_TARGET_TYPE (func_type);
+
+	  gdb_assert (TYPE_CODE (return_type) == TYPE_CODE_STRUCT
+		      || TYPE_CODE (func_type) == TYPE_CODE_UNION);
+
+	  if (TYPE_LENGTH (return_type) > 16
+	      || TYPE_LENGTH (return_type) % 4 != 0)
+	    {
+	      if (write_pass)
+		regcache_cooked_write_unsigned (regcache, RX_R15_REGNUM,
+						struct_addr);
+	    }
+	}
+
+      /* Push the arguments.  */
+      for (i = 0; i < nargs; i++)
+	{
+	  struct value *arg = args[i];
+	  const gdb_byte *arg_bits = value_contents_all (arg);
+	  struct type *arg_type = check_typedef (value_type (arg));
+	  ULONGEST arg_size = TYPE_LENGTH (arg_type);
+
+	  if (i == 0 && struct_addr != 0 && !struct_return
+	      && TYPE_CODE (arg_type) == TYPE_CODE_PTR
+	      && extract_unsigned_integer (arg_bits, 4,
+					   byte_order) == struct_addr)
+	    {
+	      /* This argument represents the address at which C++ (and
+	         possibly other languages) store their return value.
+	         Put this value in R15.  */
+	      if (write_pass)
+		regcache_cooked_write_unsigned (regcache, RX_R15_REGNUM,
+						struct_addr);
+	    }
+	  else if (TYPE_CODE (arg_type) != TYPE_CODE_STRUCT
+		   && TYPE_CODE (arg_type) != TYPE_CODE_UNION)
+	    {
+	      /* Argument is a scalar.  */
+	      if (arg_size == 8)
+		{
+		  if (i < num_register_candidate_args
+		      && arg_reg <= RX_R4_REGNUM - 1)
+		    {
+		      /* If argument registers are going to be used to pass
+		         an 8 byte scalar, the ABI specifies that two registers
+		         must be available.  */
+		      if (write_pass)
+			{
+			  regcache_cooked_write_unsigned (regcache, arg_reg,
+							  extract_unsigned_integer
+							  (arg_bits, 4,
+							   byte_order));
+			  regcache_cooked_write_unsigned (regcache,
+							  arg_reg + 1,
+							  extract_unsigned_integer
+							  (arg_bits + 4, 4,
+							   byte_order));
+			}
+		      arg_reg += 2;
+		    }
+		  else
+		    {
+		      sp_off = align_up (sp_off, 4);
+		      /* Otherwise, pass the 8 byte scalar on the stack.  */
+		      if (write_pass)
+			write_memory (sp + sp_off, arg_bits, 8);
+		      sp_off += 8;
+		    }
+		}
+	      else
+		{
+		  ULONGEST u;
+
+		  gdb_assert (arg_size <= 4);
+
+		  u =
+		    extract_unsigned_integer (arg_bits, arg_size, byte_order);
+
+		  if (i < num_register_candidate_args
+		      && arg_reg <= RX_R4_REGNUM)
+		    {
+		      if (write_pass)
+			regcache_cooked_write_unsigned (regcache, arg_reg, u);
+		      arg_reg += 1;
+		    }
+		  else
+		    {
+		      int p_arg_size = 4;
+
+		      if (TYPE_PROTOTYPED (func_type)
+			  && i < TYPE_NFIELDS (func_type))
+			{
+			  struct type *p_arg_type =
+			    TYPE_FIELD_TYPE (func_type, i);
+			  p_arg_size = TYPE_LENGTH (p_arg_type);
+			}
+
+		      sp_off = align_up (sp_off, p_arg_size);
+
+		      if (write_pass)
+			write_memory_unsigned_integer (sp + sp_off,
+						       p_arg_size, byte_order,
+						       u);
+		      sp_off += p_arg_size;
+		    }
+		}
+	    }
+	  else
+	    {
+	      /* Argument is a struct or union.  Pass as much of the struct
+	         in registers, if possible.  Pass the rest on the stack.  */
+	      while (arg_size > 0)
+		{
+		  if (i < num_register_candidate_args
+		      && arg_reg <= RX_R4_REGNUM
+		      && arg_size <= 4 * (RX_R4_REGNUM - arg_reg + 1)
+		      && arg_size % 4 == 0)
+		    {
+		      int len = min (arg_size, 4);
+
+		      if (write_pass)
+			regcache_cooked_write_unsigned (regcache, arg_reg,
+							extract_unsigned_integer
+							(arg_bits, len,
+							 byte_order));
+		      arg_bits += len;
+		      arg_size -= len;
+		      arg_reg++;
+		    }
+		  else
+		    {
+		      sp_off = align_up (sp_off, 4);
+		      if (write_pass)
+			write_memory (sp + sp_off, arg_bits, arg_size);
+		      sp_off += align_up (arg_size, 4);
+		      arg_size = 0;
+		    }
+		}
+	    }
+	}
+    }
+
+  /* Keep track of the stack address prior to pushing the return address.
+     This is the value that we'll return.  */
+  cfa = sp;
+
+  /* Push the return address.  */
+  sp = sp - 4;
+  write_memory_unsigned_integer (sp, 4, byte_order, bp_addr);
+
+  /* Update the stack pointer.  */
+  regcache_cooked_write_unsigned (regcache, RX_SP_REGNUM, sp);
+
+  return cfa;
+}
+
+/* Implement the "return_value" gdbarch method.  */
+static enum return_value_convention
+rx_return_value (struct gdbarch *gdbarch,
+		 struct type *func_type,
+		 struct type *valtype,
+		 struct regcache *regcache,
+		 gdb_byte *readbuf, const gdb_byte *writebuf)
+{
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  ULONGEST valtype_len = TYPE_LENGTH (valtype);
+
+  if (TYPE_LENGTH (valtype) > 16
+      || ((TYPE_CODE (valtype) == TYPE_CODE_STRUCT
+	   || TYPE_CODE (valtype) == TYPE_CODE_UNION)
+	  && TYPE_LENGTH (valtype) % 4 != 0))
+    return RETURN_VALUE_STRUCT_CONVENTION;
+
+  if (readbuf)
+    {
+      ULONGEST u;
+      int argreg = RX_R1_REGNUM;
+      int offset = 0;
+
+      while (valtype_len > 0)
+	{
+	  int len = min (valtype_len, 4);
+
+	  regcache_cooked_read_unsigned (regcache, argreg, &u);
+	  store_unsigned_integer (readbuf + offset, len, byte_order, u);
+	  valtype_len -= len;
+	  offset += len;
+	  argreg++;
+	}
+    }
+
+  if (writebuf)
+    {
+      ULONGEST u;
+      int argreg = RX_R1_REGNUM;
+      int offset = 0;
+
+      while (valtype_len > 0)
+	{
+	  int len = min (valtype_len, 4);
+
+	  u = extract_unsigned_integer (writebuf + offset, len, byte_order);
+	  regcache_cooked_write_unsigned (regcache, argreg, u);
+	  valtype_len -= len;
+	  offset += len;
+	  argreg++;
+	}
+    }
+
+  return RETURN_VALUE_REGISTER_CONVENTION;
+}
+
+/* Implement the "breakpoint_from_pc" gdbarch method.  */
+const gdb_byte *
+rx_breakpoint_from_pc (struct gdbarch *gdbarch, CORE_ADDR *pcptr, int *lenptr)
+{
+  static gdb_byte breakpoint[] = { 0x00 };
+  *lenptr = sizeof breakpoint;
+  return breakpoint;
+}
+
+/* Allocate and initialize a gdbarch object.  */
+static struct gdbarch *
+rx_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
+{
+  struct gdbarch *gdbarch;
+  struct gdbarch_tdep *tdep;
+  int elf_flags;
+
+  /* Extract the elf_flags if available.  */
+  if (info.abfd != NULL
+      && bfd_get_flavour (info.abfd) == bfd_target_elf_flavour)
+    elf_flags = elf_elfheader (info.abfd)->e_flags;
+  else
+    elf_flags = 0;
+
+
+  /* Try to find the architecture in the list of already defined
+     architectures.  */
+  for (arches = gdbarch_list_lookup_by_info (arches, &info);
+       arches != NULL;
+       arches = gdbarch_list_lookup_by_info (arches->next, &info))
+    {
+      if (gdbarch_tdep (arches->gdbarch)->elf_flags != elf_flags)
+	continue;
+
+      return arches->gdbarch;
+    }
+
+  /* None found, create a new architecture from the information
+     provided.  */
+  tdep = (struct gdbarch_tdep *) xmalloc (sizeof (struct gdbarch_tdep));
+  gdbarch = gdbarch_alloc (&info, tdep);
+  tdep->elf_flags = elf_flags;
+
+  set_gdbarch_num_regs (gdbarch, RX_NUM_REGS);
+  set_gdbarch_num_pseudo_regs (gdbarch, 0);
+  set_gdbarch_register_name (gdbarch, rx_register_name);
+  set_gdbarch_register_type (gdbarch, rx_register_type);
+  set_gdbarch_pc_regnum (gdbarch, RX_PC_REGNUM);
+  set_gdbarch_sp_regnum (gdbarch, RX_SP_REGNUM);
+  set_gdbarch_inner_than (gdbarch, core_addr_lessthan);
+  set_gdbarch_decr_pc_after_break (gdbarch, 1);
+  set_gdbarch_breakpoint_from_pc (gdbarch, rx_breakpoint_from_pc);
+  set_gdbarch_skip_prologue (gdbarch, rx_skip_prologue);
+
+  set_gdbarch_print_insn (gdbarch, print_insn_rx);
+
+  set_gdbarch_unwind_pc (gdbarch, rx_unwind_pc);
+  set_gdbarch_unwind_sp (gdbarch, rx_unwind_sp);
+
+  /* Target builtin data types.  */
+  set_gdbarch_char_signed (gdbarch, 0);
+  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_ptr_bit (gdbarch, 32);
+  set_gdbarch_float_bit (gdbarch, 32);
+  set_gdbarch_float_format (gdbarch, floatformats_ieee_single);
+  if (elf_flags & E_FLAG_RX_64BIT_DOUBLES)
+    {
+      set_gdbarch_double_bit (gdbarch, 64);
+      set_gdbarch_long_double_bit (gdbarch, 64);
+      set_gdbarch_double_format (gdbarch, floatformats_ieee_double);
+      set_gdbarch_long_double_format (gdbarch, floatformats_ieee_double);
+    }
+  else
+    {
+      set_gdbarch_double_bit (gdbarch, 32);
+      set_gdbarch_long_double_bit (gdbarch, 32);
+      set_gdbarch_double_format (gdbarch, floatformats_ieee_single);
+      set_gdbarch_long_double_format (gdbarch, floatformats_ieee_single);
+    }
+
+  /* Frame unwinding.  */
+#if 0
+  /* Note: The test results are better with the dwarf2 unwinder disabled,
+     so it's turned off for now.  */
+  dwarf2_append_unwinders (gdbarch);
+#endif
+  frame_unwind_append_unwinder (gdbarch, &rx_frame_unwind);
+
+  /* Methods for saving / extracting a dummy frame's ID.
+     The ID's stack address must match the SP value returned by
+     PUSH_DUMMY_CALL, and saved by generic_save_dummy_frame_tos.  */
+  set_gdbarch_dummy_id (gdbarch, rx_dummy_id);
+  set_gdbarch_push_dummy_call (gdbarch, rx_push_dummy_call);
+  set_gdbarch_return_value (gdbarch, rx_return_value);
+
+  /* Virtual tables.  */
+  set_gdbarch_vbit_in_delta (gdbarch, 1);
+
+  return gdbarch;
+}
+
+/* Register the above initialization routine.  */
+void
+_initialize_rx_tdep (void)
+{
+  register_gdbarch_init (bfd_arch_rx, rx_gdbarch_init);
+}



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