[RFA 3/5] New port: CR16: gdb port

Kaushik Phatak Kaushik.Phatak@kpitcummins.com
Fri Oct 26 05:15:00 GMT 2012


Hi Joel,

>> Can you declare those externs somewhere in opcode instead?
Yes, taken care of. I have also moved the global declarations from
opcodes/cr16-dis.c as externs into opcode/cr16.h. This was, both cr16-dis.c and
cr16-tdep.c can use these.

>> But I would make sure that the type of the variables match the return type.
OK, I have taken care of this.

Please find below an updated patch for cr16 gdb. I have also attached the same.
Additionally I have also attached the bfd hunk which moves the globals into
externs in the opcodes file. I will submit that to binutils once my gdb port 
gets a go ahead.

Thanks again for taking time to review this port.

Regards,
Kaushik


2012-10-26 Kaushik Phatak  <kaushik.phatak@kpitcummins.com>

	gdb/Changelog
	* configure.tgt: Handle cr16*-*-*linux and cr16*-*-*.
	* cr16-linux-tdep.c: New file.
	* cr16-tdep.c: New file.
	* cr16-tdep.h: New file.
	
--- ./gdb_src.orig/gdb/configure.tgt	2012-08-02 01:18:44.000000000 +0530
+++ ./gdb_src/gdb/configure.tgt	2012-10-23 15:09:24.000000000 +0530
@@ -116,6 +116,18 @@ bfin-*-*)
 	gdb_sim=../sim/bfin/libsim.a
 	;;
 
+cr16*-*-*linux)
+	# Target: CR16 processor
+	gdb_target_obs="cr16-tdep.o cr16-linux-tdep.o linux-tdep.o"
+	gdb_sim=../sim/cr16/libsim.a
+	;;
+
+cr16*-*-*)
+	# Target: CR16 processor
+	gdb_target_obs="cr16-tdep.o"
+	gdb_sim=../sim/cr16/libsim.a
+	;;
+
 cris*)
 	# Target: CRIS
 	gdb_target_obs="cris-tdep.o solib-svr4.o"
--- ./gdb_src.orig/gdb/cr16-linux-tdep.c	1970-01-01 05:30:00.000000000 +0530
+++ ./gdb_src/gdb/cr16-linux-tdep.c	2012-10-23 15:22:34.000000000 +0530
@@ -0,0 +1,103 @@
+/* Target-dependent code for GNU/Linux on the Sitel CR16 processors.
+
+   Copyright 2012 Free Software Foundation, Inc.
+
+   Contributed by Kaushik Phatak (kaushik.phatak@kpitcummins.com)
+   KPIT Cummins Infosystems Limited, Pune India.
+
+   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 "osabi.h"
+#include "elf-bfd.h"
+#include "elf/cr16.h"
+#include "linux-tdep.h"
+#include "solib-svr4.h"
+#include "symtab.h"
+#include "cr16-tdep.h"
+
+/* Number of registers available for Linux targets  */
+#define CR16_LINUX_NUM_REGS  21
+
+/* The breakpoint instruction used by uClinux target  */
+static const gdb_byte breakpoint_uclinux[] = { 0xC7, 0x00 };
+
+/* Implement the "register_name" gdbarch method.  */
+
+static const char *
+cr16_linux_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",
+    "ra",
+    "psr",
+    "pc",
+    "r0r1_orig",
+    "intbase",
+    "usp",
+    "cfg"
+  };
+
+  return reg_names[regnr];
+}
+
+/* OS specific initialization of gdbarch.  */
+
+static void
+cr16_uclinux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
+  linux_init_abi (info, gdbarch);
+
+  set_gdbarch_num_regs (gdbarch, CR16_LINUX_NUM_REGS);
+  set_gdbarch_register_name (gdbarch, cr16_linux_register_name);
+
+  /* The opcode of excp bpt is 0x00C8, however for uclinux we will
+     use the excp flg (0x00C7) to insert a breakpoint.  The excp bpt
+     requires external hardware support for breakpoints to work on
+     CR16 target.  Software based breakpoints are implemented in the
+     kernel using excp flg and tested on the SC14452 target.  Use
+     0x00C7 with gdbserver/kernel and 0x00C8 for sim/ELF.  We
+     represent the breakpoint in little endian format since CR16
+     supports only little endian.  */
+  tdep->breakpoint = breakpoint_uclinux;
+
+}
+
+/* Provide a prototype to silence -Wmissing-prototypes.  */
+extern initialize_file_ftype _initialize_cr16_linux_tdep;
+
+void
+_initialize_cr16_linux_tdep (void)
+{
+  gdbarch_register_osabi (bfd_arch_cr16, 0, GDB_OSABI_LINUX,
+			  cr16_uclinux_init_abi);
+}
--- ./gdb_src.orig/gdb/cr16-tdep.c	1970-01-01 05:30:00.000000000 +0530
+++ ./gdb_src/gdb/cr16-tdep.c	2012-10-25 10:44:15.000000000 +0530
@@ -0,0 +1,904 @@
+/* Target-dependent code for the Sitel CR16 for GDB, the GNU debugger.
+ 
+   Copyright (C) 2012 Free Software Foundation, Inc.
+ 
+   Contributed by Kaushik Phatak (kaushik.phatak@kpitcummins.com)
+   KPIT Cummins Infosystems Limited, Pune India.
+   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/cr16.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 "gdb/sim-cr16.h"
+#include "elf/cr16.h"
+#include "elf-bfd.h"
+#include "osabi.h"
+#include "cr16-tdep.h"
+
+/* Number of registers available for ELF targets.  */
+#define CR16_NUM_REGS  22
+
+/* The breakpoint instruction used with sim for ELF targets.  */
+static const gdb_byte breakpoint_elf[] = { 0xC8, 0x00 };
+
+/* Certain important register numbers.  */
+enum
+{
+  CR16_R0_REGNUM = 0,
+  CR16_R7_REGNUM = 7,
+  CR16_R12_REGNUM = 12,
+  CR16_FP_REGNUM = 13,
+  CR16_RA_REGNUM = 14,
+  CR16_SP_REGNUM = 15,
+  CR16_PC_REGNUM = 16,
+};
+
+/* This structure holds the results of a prologue analysis.  */
+struct cr16_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[CR16_NUM_REGS];
+};
+
+/* Implement the "register_name" gdbarch method.  */
+
+static const char *
+cr16_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",
+    "ra",
+    "sp",
+    "pc",
+    "isp",
+    "usp",
+    "intbase",
+    "psr",
+    "cfg"
+  };
+
+  return reg_names[regnr];
+}
+
+
+/* Implement the "register_type" gdbarch method.  */
+
+static struct type *
+cr16_register_type (struct gdbarch *gdbarch, int reg_nr)
+{
+  switch (reg_nr)
+    {
+    case CR16_PC_REGNUM:	/* Note:PC in CR16 is of 24 bits.  */
+      return builtin_type (gdbarch)->builtin_func_ptr;
+
+    case CR16_RA_REGNUM:	/* Return address reg.  */
+      return builtin_type (gdbarch)->builtin_data_ptr;
+      break;
+
+    case CR16_FP_REGNUM:	/*Frame Pointer reg.  */
+    case CR16_SP_REGNUM:	/*Stack Pointer reg.  */
+      return builtin_type (gdbarch)->builtin_data_ptr;
+      break;
+
+    case SIM_CR16_ISP_REGNUM:
+    case SIM_CR16_USP_REGNUM:
+    case SIM_CR16_INTBASE_REGNUM:
+      return builtin_type (gdbarch)->builtin_int32;
+      break;
+
+    case SIM_CR16_PSR_REGNUM:
+    case SIM_CR16_CFG_REGNUM:
+      return builtin_type (gdbarch)->builtin_uint32;
+      break;
+
+    case SIM_CR16_R0_REGNUM:
+    case SIM_CR16_R1_REGNUM:
+    case SIM_CR16_R2_REGNUM:
+    case SIM_CR16_R3_REGNUM:
+    case SIM_CR16_R4_REGNUM:
+    case SIM_CR16_R5_REGNUM:
+    case SIM_CR16_R6_REGNUM:
+    case SIM_CR16_R7_REGNUM:
+    case SIM_CR16_R8_REGNUM:
+    case SIM_CR16_R9_REGNUM:
+    case SIM_CR16_R10_REGNUM:
+    case SIM_CR16_R11_REGNUM:
+      return builtin_type (gdbarch)->builtin_int16;
+      break;
+
+    case SIM_CR16_R12_REGNUM:
+      return builtin_type (gdbarch)->builtin_int32;
+      break;
+
+    default:
+      return builtin_type (gdbarch)->builtin_int32;
+      break;
+    }
+}
+
+/* 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 cr16_prologue *result = (struct cr16_prologue *) result_untyped;
+
+  if (value.kind == pvk_register
+      && value.k == 0
+      && pv_is_register (addr, CR16_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 cr16_get_opcode_byte_handle
+{
+  CORE_ADDR pc;
+};
+
+/* Analyze a prologue starting at START_PC, going no further than
+   LIMIT_PC.  Fill in RESULT as appropriate.  */
+
+static void
+cr16_analyze_prologue (CORE_ADDR start_pc,
+		       CORE_ADDR limit_pc, struct cr16_prologue *result)
+{
+  CORE_ADDR pc, next_pc;
+  gdb_byte insn_byte1, insn_byte2;
+  int rn;
+  int length;
+  pv_t reg[CR16_NUM_REGS];
+  struct pv_area *stack;
+  struct cleanup *back_to;
+  CORE_ADDR after_last_frame_setup_insn = start_pc;
+  int is_decoded;
+
+  memset (result, 0, sizeof (*result));
+
+  for (rn = 0; rn < CR16_NUM_REGS; rn++)
+    {
+      reg[rn] = pv_register (rn, 0);
+      result->reg_offset[rn] = 1;
+    }
+
+  stack = make_pv_area (CR16_SP_REGNUM, gdbarch_addr_bit (target_gdbarch));
+  back_to = make_cleanup_free_pv_area (stack);
+
+  pc = start_pc;
+  while (pc < limit_pc)
+    {
+      gdb_byte buf[6];
+
+      /* Read 6 bytes, max 48 bit opcode.  */
+      target_read_memory (pc, buf, 6);
+      words[0] = buf[1] << 8 | buf[0];
+      words[1] = buf[3] << 8 | buf[2];
+      words[2] = buf[5] << 8 | buf[4];
+      allWords =
+	((ULONGLONG) words[0] << 32) + ((unsigned long) words[1] << 16) +
+	words[2];
+
+      /* Find a matching opcode in table.
+         Nonzero means instruction has a match.  */
+      is_decoded = match_opcode ();
+      make_instruction ();
+      length = currInsn.size;
+      next_pc = pc + length;
+      insn_byte1 = (words[0] >> 8) & 0xFF;
+
+      /* If PUSH, then save RA and other regs.  */
+      if (insn_byte1 == 0x01)
+	{
+	  int r1, r2;
+	  int r;
+
+	  insn_byte2 = words[0];
+
+	  if (insn_byte2 & 0x80)
+	    {
+	      reg[CR16_SP_REGNUM] = pv_add_constant (reg[CR16_SP_REGNUM], -4);
+	      pv_area_store (stack, reg[CR16_SP_REGNUM], 4,
+			     reg[CR16_RA_REGNUM]);
+	    }
+	  /* Start Register=r1, 3 bit imm count=r2.  */
+	  r1 = insn_byte2 & 0x0F;
+	  r2 = ((insn_byte2 & 0x70) >> 4);
+	  r2 = r2 + r1 + 1;
+
+	  for (r = r1; r < r2; r++)
+	    {
+	      if (r >= CR16_R12_REGNUM)
+		{
+		  reg[CR16_SP_REGNUM] =
+		    pv_add_constant (reg[CR16_SP_REGNUM], -4);
+		  pv_area_store (stack, reg[CR16_SP_REGNUM], 4, reg[r]);
+		  r++;
+		}
+	      else
+		{
+		  reg[CR16_SP_REGNUM] =
+		    pv_add_constant (reg[CR16_SP_REGNUM], -2);
+		  pv_area_store (stack, reg[CR16_SP_REGNUM], 2, reg[r]);
+		}
+	    }
+	  after_last_frame_setup_insn = next_pc;
+	}
+      /* Add constant to SP.  */
+      else if (insn_byte1 == 0x60)
+	{
+	  int rdst;
+	  signed short addend;
+
+	  insn_byte2 = words[0];
+	  rdst = insn_byte2 & 0x0F;
+	  if (rdst == CR16_SP_REGNUM)
+	    {
+	      if (length == 2)
+		{
+		  addend = (insn_byte2 & 0xF0) >> 4;
+		  reg[rdst] = pv_add_constant (reg[rdst], addend);
+		}
+	      if (length == 4)
+		{
+		  addend = words[1];
+		  reg[rdst] = pv_add_constant (reg[rdst], addend);
+		}
+	      after_last_frame_setup_insn = next_pc;
+	    }
+	}
+      /* Check for MOVD insn.  */
+      else if (insn_byte1 == 0x55)
+	{
+	  int rdst, rsrc;
+
+	  insn_byte2 = words[0];
+	  rsrc = (insn_byte2 & 0xF0) >> 4;
+	  rdst = (insn_byte2 & 0x0F);
+	  reg[rdst] = reg[rsrc];
+	  if (rsrc == CR16_SP_REGNUM && rdst == CR16_FP_REGNUM)
+	    after_last_frame_setup_insn = next_pc;
+	}
+      else if (((insn_byte1 >> 4) & 0x0F) == 0xd)
+	{
+	  /* This moves an argument register to the stack.  Don't
+	     record it, but allow it to be a part of the prologue.  */
+	  after_last_frame_setup_insn = next_pc;
+	}
+      else
+	{
+	  break;		/* Terminate the prologue scan.  */
+	}
+
+      pc = next_pc;
+    }
+
+  /* Is the frame size (offset, really) a known constant?  */
+  if (pv_is_register (reg[CR16_SP_REGNUM], CR16_SP_REGNUM))
+    result->frame_size = reg[CR16_SP_REGNUM].k;
+
+  /* Was the frame pointer initialized?  */
+  if (pv_is_register (reg[CR16_FP_REGNUM], CR16_SP_REGNUM))
+    {
+      result->has_frame_ptr = 1;
+      result->frame_ptr_offset = reg[CR16_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
+cr16_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
+{
+  const char *name;
+  CORE_ADDR func_addr, func_end;
+  struct cr16_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;
+
+  cr16_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 cr16_prologue *
+cr16_analyze_frame_prologue (struct frame_info *this_frame,
+			     void **this_prologue_cache)
+{
+  if (*this_prologue_cache)
+    return *this_prologue_cache;
+
+  CORE_ADDR func_start, stop_addr;
+
+  *this_prologue_cache = FRAME_OBSTACK_ZALLOC (struct cr16_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;
+
+  cr16_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
+cr16_frame_base (struct frame_info *this_frame, void **this_prologue_cache)
+{
+  struct cr16_prologue *p
+    = cr16_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, CR16_FP_REGNUM);
+      return fp - p->frame_ptr_offset;
+    }
+  else
+    {
+      CORE_ADDR sp = get_frame_register_unsigned (this_frame, CR16_SP_REGNUM);
+      return sp - p->frame_size;
+    }
+}
+
+/* Implement the "frame_this_id" method for unwinding frames.  */
+
+static void
+cr16_frame_this_id (struct frame_info *this_frame,
+		    void **this_prologue_cache, struct frame_id *this_id)
+{
+  *this_id =
+    frame_id_build (cr16_frame_base (this_frame, this_prologue_cache),
+		    get_frame_func (this_frame));
+}
+
+/* Implement the "frame_prev_register" method for unwinding frames.  */
+
+static struct value *
+cr16_frame_prev_register (struct frame_info *this_frame,
+			  void **this_prologue_cache, int regnum)
+{
+  struct cr16_prologue *p =
+    cr16_analyze_frame_prologue (this_frame, this_prologue_cache);
+  CORE_ADDR frame_base = cr16_frame_base (this_frame, this_prologue_cache);
+  int reg_size = register_size (get_frame_arch (this_frame), regnum);
+  ULONGEST ra_prev;
+
+  if (regnum == CR16_SP_REGNUM)
+    return frame_unwind_got_constant (this_frame, regnum, frame_base);
+
+  /* The call instruction has saved the return address on the RA
+     register, CR16_R13_REGNUM.  So, we need not adjust anything
+     directly.  We will analyze prologue as this RA register is
+     pushed onto stack for further leaf function calls to work.  */
+  else if (regnum == CR16_PC_REGNUM)
+    {
+      ra_prev = frame_unwind_register_unsigned (this_frame, CR16_RA_REGNUM);
+      ra_prev = ra_prev << 1;
+      return frame_unwind_got_constant (this_frame, CR16_PC_REGNUM, ra_prev);
+    }
+
+  /* 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 cr16_frame_unwind = 
+{
+  NORMAL_FRAME,
+  default_frame_unwind_stop_reason,
+  cr16_frame_this_id,
+  cr16_frame_prev_register,
+  NULL,
+  default_frame_sniffer
+};
+
+/* Implement the "unwind_pc" gdbarch method.  */
+
+static CORE_ADDR
+cr16_unwind_pc (struct gdbarch *gdbarch, struct frame_info *this_frame)
+{
+  CORE_ADDR pc;
+  
+  pc = frame_unwind_register_unsigned (this_frame, CR16_PC_REGNUM);
+  return pc;
+}
+
+/* Implement the "unwind_sp" gdbarch method.  */
+
+static CORE_ADDR
+cr16_unwind_sp (struct gdbarch *gdbarch, struct frame_info *this_frame)
+{
+  CORE_ADDR sp;
+
+  sp = frame_unwind_register_unsigned (this_frame, CR16_SP_REGNUM);
+  return sp;
+}
+
+/* Implement the "dummy_id" gdbarch method.  */
+
+static struct frame_id
+cr16_dummy_id (struct gdbarch *gdbarch, struct frame_info *this_frame)
+{
+  return
+    frame_id_build (get_frame_register_unsigned (this_frame, CR16_SP_REGNUM),
+		    get_frame_pc (this_frame));
+}
+
+/* Implement the "push_dummy_call" gdbarch method.  */
+
+static CORE_ADDR
+cr16_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 = CR16_R0_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, CR16_R12_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 R12.  */
+	      if (write_pass)
+		regcache_cooked_write_unsigned (regcache, CR16_R12_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 <= CR16_R7_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 <= CR16_R7_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, as possible.  Pass the rest on the stack.  */
+	      while (arg_size > 0)
+		{
+		  if (i < num_register_candidate_args
+		      && arg_reg <= CR16_R7_REGNUM
+		      && arg_size <= 4 * (CR16_R7_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, CR16_SP_REGNUM, sp);
+
+  return cfa;
+}
+
+/* Implement the "return_value" gdbarch method.  */
+
+static enum return_value_convention
+cr16_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 = CR16_R0_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 = CR16_R0_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.  */
+
+static const gdb_byte *
+cr16_breakpoint_from_pc (struct gdbarch *gdbarch, CORE_ADDR * pcptr,
+			 int *lenptr)
+{
+  /* We use different breakpoint instructions for ELF and uClinux.
+     See cr16-linux-tdep.c for more details.  */
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
+  *lenptr = 2;
+  if (tdep == NULL || tdep->breakpoint == NULL)
+    {
+      return breakpoint_elf;
+    }
+  return tdep->breakpoint;
+}
+
+/* Allocate and initialize a gdbarch object.  */
+
+static struct gdbarch *
+cr16_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 *) xcalloc (1, sizeof (struct gdbarch_tdep));
+  tdep->elf_flags = elf_flags;
+  gdbarch = gdbarch_alloc (&info, tdep);
+
+  set_gdbarch_num_pseudo_regs (gdbarch, 0);
+  set_gdbarch_num_regs (gdbarch, CR16_NUM_REGS);
+  set_gdbarch_register_name (gdbarch, cr16_register_name);
+  set_gdbarch_register_type (gdbarch, cr16_register_type);
+  set_gdbarch_pc_regnum (gdbarch, CR16_PC_REGNUM);
+  set_gdbarch_sp_regnum (gdbarch, CR16_SP_REGNUM);
+  set_gdbarch_inner_than (gdbarch, core_addr_lessthan);
+  set_gdbarch_decr_pc_after_break (gdbarch, 2);
+  set_gdbarch_breakpoint_from_pc (gdbarch, cr16_breakpoint_from_pc);
+  set_gdbarch_skip_prologue (gdbarch, cr16_skip_prologue);
+
+  /* Passing NULL  values in the following two functions
+     for the time being, to fix later.  */
+  set_gdbarch_print_insn (gdbarch, print_insn_cr16);
+  set_gdbarch_unwind_pc (gdbarch, cr16_unwind_pc);
+  set_gdbarch_unwind_sp (gdbarch, cr16_unwind_sp);
+
+  /* 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, cr16_dummy_id);
+  set_gdbarch_push_dummy_call (gdbarch, cr16_push_dummy_call);
+  /* Target builtin data types.  */
+  set_gdbarch_char_signed (gdbarch, 8);
+  set_gdbarch_short_bit (gdbarch, 16);
+  set_gdbarch_int_bit (gdbarch, 16);
+  set_gdbarch_long_bit (gdbarch, 32);
+  set_gdbarch_long_long_bit (gdbarch, 64);
+  set_gdbarch_float_bit (gdbarch, 32);
+
+  set_gdbarch_ptr_bit (gdbarch, 32);
+  set_gdbarch_float_format (gdbarch, floatformats_ieee_single);
+  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);
+
+  frame_unwind_append_unwinder (gdbarch, &cr16_frame_unwind);
+  set_gdbarch_return_value (gdbarch, cr16_return_value);
+
+  /* Hook in ABI-specific overrides, if they have been registered.  */
+  gdbarch_init_osabi (info, gdbarch);
+
+  return gdbarch;
+
+}
+
+/* -Wmissing-prototypes.  */
+extern initialize_file_ftype _initialize_cr16_tdep;
+
+/* Register the above initialization routine.  */
+
+void
+_initialize_cr16_tdep (void)
+{
+  register_gdbarch_init (bfd_arch_cr16, cr16_gdbarch_init);
+}
--- ./gdb_src.orig/gdb/cr16-tdep.h	1970-01-01 05:30:00.000000000 +0530
+++ ./gdb_src/gdb/cr16-tdep.h	2012-10-23 15:22:53.000000000 +0530
@@ -0,0 +1,32 @@
+/* GNU/Linux on  CR16 target support.
+   Copyright (C) 2012 Free Software Foundation, Inc.
+
+   Contributed by Kaushik Phatak (kaushik.phatak@kpitcummins.com)
+   KPIT Cummins Infosystems Limited, Pune India.
+
+   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/>.  */
+
+
+/* Target-dependent structure in gdbarch.  */
+
+struct gdbarch_tdep
+{
+  /* The ELF header flags specify the multilib used.  */
+  int elf_flags;
+
+  /* Breakpoint instruction.  */
+  const gdb_byte *breakpoint;
+};

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