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/* Target-machine dependent code for Motorola MCore for GDB, the GNU debugger

   Copyright 1999, 2000, 2001 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 2 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, write to the Free Software

   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

#include "defs.h"

#include "frame.h"

#include "symtab.h"

#include "value.h"

#include "gdbcmd.h"

#include "regcache.h"

#include "symfile.h"

#include "gdbcore.h"

#include "inferior.h"

/* Functions declared and used only in this file */

static CORE_ADDR mcore_analyze_prologue (struct frame_info *fi, CORE_ADDR pc, int skip_prologue);

static struct frame_info *analyze_dummy_frame (CORE_ADDR pc, CORE_ADDR frame);

static int get_insn (CORE_ADDR pc);

/* Functions exported from this file */

int mcore_use_struct_convention (int gcc_p, struct type *type);

void _initialize_mcore (void);

void mcore_init_extra_frame_info (struct frame_info *fi);

CORE_ADDR mcore_frame_saved_pc (struct frame_info *fi);

CORE_ADDR mcore_find_callers_reg (struct frame_info *fi, int regnum);

CORE_ADDR mcore_frame_args_address (struct frame_info *fi);

CORE_ADDR mcore_frame_locals_address (struct frame_info *fi);

void mcore_virtual_frame_pointer (CORE_ADDR pc, long *reg, long *offset);

CORE_ADDR mcore_push_return_address (CORE_ADDR pc, CORE_ADDR sp);

CORE_ADDR mcore_push_arguments (int nargs, value_ptr * args, CORE_ADDR sp,

                        unsigned char struct_return, CORE_ADDR struct_addr);

void mcore_pop_frame (struct frame_info *fi);

CORE_ADDR mcore_skip_prologue (CORE_ADDR pc);

CORE_ADDR mcore_frame_chain (struct frame_info *fi);

unsigned char *mcore_breakpoint_from_pc (CORE_ADDR * bp_addr, int *bp_size);

int mcore_use_struct_convention (int gcc_p, struct type *type);

void mcore_store_return_value (struct type *type, char *valbuf);

CORE_ADDR mcore_extract_struct_value_address (char *regbuf);

void mcore_extract_return_value (struct type *type, char *regbuf, char *valbuf);

#ifdef MCORE_DEBUG

int mcore_debug = 0;

#endif

/* The registers of the Motorola MCore processors */

/* *INDENT-OFF* */

char *mcore_register_names[] =

{ "r0",   "r1",  "r2",    "r3",   "r4",   "r5",   "r6",   "r7",

  "r8",   "r9",  "r10",   "r11",  "r12",  "r13",  "r14",  "r15",

  "ar0",  "ar1", "ar2",   "ar3",  "ar4",  "ar5",  "ar6",  "ar7",

  "ar8",  "ar9", "ar10", "ar11",  "ar12", "ar13", "ar14", "ar15",

  "psr",  "vbr", "epsr",  "fpsr", "epc",  "fpc",  "ss0",  "ss1",

  "ss2",  "ss3", "ss4",   "gcr",  "gsr",  "cr13", "cr14", "cr15",

  "cr16", "cr17", "cr18", "cr19", "cr20", "cr21", "cr22", "cr23",

  "cr24", "cr25", "cr26", "cr27", "cr28", "cr29", "cr30", "cr31",

  "pc" };

/* *INDENT-ON* */

/* Additional info that we use for managing frames */

struct frame_extra_info

  {

    /* A generic status word */

    int status;

    /* Size of this frame */

    int framesize;

    /* The register that is acting as a frame pointer, if

       it is being used.  This is undefined if status

       does not contain the flag MY_FRAME_IN_FP. */

    int fp_regnum;

  };

/* frame_extra_info status flags */

/* The base of the current frame is actually in the stack pointer.

   This happens when there is no frame pointer (MCore ABI does not

   require a frame pointer) or when we're stopped in the prologue or

   epilogue itself.  In these cases, mcore_analyze_prologue will need

   to update fi->frame before returning or analyzing the register

   save instructions. */

#define MY_FRAME_IN_SP 0x1

/* The base of the current frame is in a frame pointer register.

   This register is noted in frame_extra_info->fp_regnum.

   Note that the existence of an FP might also indicate that the

   function has called alloca. */

#define MY_FRAME_IN_FP 0x2

/* This flag is set to indicate that this frame is the top-most

   frame. This tells frame chain not to bother trying to unwind

   beyond this frame. */

#define NO_MORE_FRAMES 0x4

/* Instruction macros used for analyzing the prologue */

#define IS_SUBI0(x)   (((x) & 0xfe0f) == 0x2400)        /* subi r0,oimm5    */

#define IS_STM(x)     (((x) & 0xfff0) == 0x0070)        /* stm rf-r15,r0    */

#define IS_STWx0(x)   (((x) & 0xf00f) == 0x9000)        /* stw rz,(r0,disp) */

#define IS_STWxy(x)   (((x) & 0xf000) == 0x9000)        /* stw rx,(ry,disp) */

#define IS_MOVx0(x)   (((x) & 0xfff0) == 0x1200)        /* mov rn,r0        */

#define IS_LRW1(x)    (((x) & 0xff00) == 0x7100)        /* lrw r1,literal   */

#define IS_MOVI1(x)   (((x) & 0xf80f) == 0x6001)        /* movi r1,imm7     */

#define IS_BGENI1(x)  (((x) & 0xfe0f) == 0x3201)        /* bgeni r1,imm5    */

#define IS_BMASKI1(x) (((x) & 0xfe0f) == 0x2C01)        /* bmaski r1,imm5   */

#define IS_ADDI1(x)   (((x) & 0xfe0f) == 0x2001)        /* addi r1,oimm5    */

#define IS_SUBI1(x)   (((x) & 0xfe0f) == 0x2401)        /* subi r1,oimm5    */

#define IS_RSUBI1(x)  (((x) & 0xfe0f) == 0x2801)        /* rsubi r1,imm5    */

#define IS_NOT1(x)    (((x) & 0xffff) == 0x01f1)        /* not r1           */

#define IS_ROTLI1(x)  (((x) & 0xfe0f) == 0x3801)        /* rotli r1,imm5    */

#define IS_BSETI1(x)  (((x) & 0xfe0f) == 0x3401)        /* bseti r1,imm5    */

#define IS_BCLRI1(x)  (((x) & 0xfe0f) == 0x3001)        /* bclri r1,imm5    */

#define IS_IXH1(x)    (((x) & 0xffff) == 0x1d11)        /* ixh r1,r1        */

#define IS_IXW1(x)    (((x) & 0xffff) == 0x1511)        /* ixw r1,r1        */

#define IS_SUB01(x)   (((x) & 0xffff) == 0x0510)        /* subu r0,r1       */

#define IS_RTS(x)     (((x) & 0xffff) == 0x00cf)        /* jmp r15          */

#define IS_R1_ADJUSTER(x) \

    (IS_ADDI1(x) || IS_SUBI1(x) || IS_ROTLI1(x) || IS_BSETI1(x) \

     || IS_BCLRI1(x) || IS_RSUBI1(x) || IS_NOT1(x) \

     || IS_IXH1(x) || IS_IXW1(x))

#ifdef MCORE_DEBUG

static void

mcore_dump_insn (char *commnt, CORE_ADDR pc, int insn)

{

  if (mcore_debug)

    {

      printf_filtered ("MCORE:  %s %08x %08x ",

                       commnt, (unsigned int) pc, (unsigned int) insn);

      (*tm_print_insn) (pc, &tm_print_insn_info);

      printf_filtered ("\n");

    }

}

#define mcore_insn_debug(args) { if (mcore_debug) printf_filtered args; }

#else /* !MCORE_DEBUG */

#define mcore_dump_insn(a,b,c) {}

#define mcore_insn_debug(args) {}

#endif

/* Given the address at which to insert a breakpoint (BP_ADDR),

   what will that breakpoint be?

   For MCore, we have a breakpoint instruction. Since all MCore

   instructions are 16 bits, this is all we need, regardless of

   address. bpkt = 0x0000 */

unsigned char *

mcore_breakpoint_from_pc (CORE_ADDR * bp_addr, int *bp_size)

{

  static char breakpoint[] =

  {0x00, 0x00};

  *bp_size = 2;

  return breakpoint;

}

/* Helper function for several routines below.  This funtion simply

   sets up a fake, aka dummy, frame (not a _call_ dummy frame) that

   we can analyze with mcore_analyze_prologue. */

static struct frame_info *

analyze_dummy_frame (CORE_ADDR pc, CORE_ADDR frame)

{

  static struct frame_info *dummy = NULL;

  if (dummy == NULL)

    {

      dummy = (struct frame_info *) xmalloc (sizeof (struct frame_info));

      dummy->saved_regs = (CORE_ADDR *) xmalloc (SIZEOF_FRAME_SAVED_REGS);

      dummy->extra_info =

        (struct frame_extra_info *) xmalloc (sizeof (struct frame_extra_info));

    }

  dummy->next = NULL;

  dummy->prev = NULL;

  dummy->pc = pc;

  dummy->frame = frame;

  dummy->extra_info->status = 0;

  dummy->extra_info->framesize = 0;

  memset (dummy->saved_regs, '\000', SIZEOF_FRAME_SAVED_REGS);

  mcore_analyze_prologue (dummy, 0, 0);

  return dummy;

}

/* Function prologues on the Motorola MCore processors consist of:

   - adjustments to the stack pointer (r1 used as scratch register)

   - store word/multiples that use r0 as the base address

   - making a copy of r0 into another register (a "frame" pointer)

   Note that the MCore really doesn't have a real frame pointer.

   Instead, the compiler may copy the SP into a register (usually

   r8) to act as an arg pointer.  For our target-dependent purposes,

   the frame info's "frame" member will be the beginning of the

   frame. The SP could, in fact, point below this.

   The prologue ends when an instruction fails to meet either of

   the first two criteria or when an FP is made.  We make a special

   exception for gcc. When compiling unoptimized code, gcc will

   setup stack slots. We need to make sure that we skip the filling

   of these stack slots as much as possible. This is only done

   when SKIP_PROLOGUE is set, so that it does not mess up

   backtraces. */

/* Analyze the prologue of frame FI to determine where registers are saved,

   the end of the prologue, etc. Return the address of the first line

   of "real" code (i.e., the end of the prologue). */

static CORE_ADDR

mcore_analyze_prologue (struct frame_info *fi, CORE_ADDR pc, int skip_prologue)

{

  CORE_ADDR func_addr, func_end, addr, stop;

  CORE_ADDR stack_size;

  int insn, rn;

  int status;

  int fp_regnum = 0; /* dummy, valid when (flags & MY_FRAME_IN_FP) */

  int flags;

  int framesize;

  int register_offsets[NUM_REGS];

  char *name;

  /* If provided, use the PC in the frame to look up the

     start of this function. */

  pc = (fi == NULL ? pc : fi->pc);

  /* Find the start of this function. */

  status = find_pc_partial_function (pc, &name, &func_addr, &func_end);

  /* If the start of this function could not be found or if the debbuger

     is stopped at the first instruction of the prologue, do nothing. */

  if (status == 0)

    return pc;

  /* If the debugger is entry function, give up. */

  if (func_addr == entry_point_address ())

    {

      if (fi != NULL)

        fi->extra_info->status |= NO_MORE_FRAMES;

      return pc;

    }

  /* At the start of a function, our frame is in the stack pointer. */

  flags = MY_FRAME_IN_SP;

  /* Start decoding the prologue.  We start by checking two special cases:

     1. We're about to return

     2. We're at the first insn of the prologue.

     If we're about to return, our frame has already been deallocated.

     If we are stopped at the first instruction of a prologue,

     then our frame has not yet been set up. */

  /* Get the first insn from memory (all MCore instructions are 16 bits) */

  mcore_insn_debug (("MCORE: starting prologue decoding\n"));

  insn = get_insn (pc);

  mcore_dump_insn ("got 1: ", pc, insn);

  /* Check for return. */

  if (fi != NULL && IS_RTS (insn))

    {

      mcore_insn_debug (("MCORE: got jmp r15"));

      if (fi->next == NULL)

        fi->frame = read_sp ();

      return fi->pc;

    }

  /* Check for first insn of prologue */

  if (fi != NULL && fi->pc == func_addr)

    {

      if (fi->next == NULL)

        fi->frame = read_sp ();

      return fi->pc;

    }

  /* Figure out where to stop scanning */

  stop = (fi ? fi->pc : func_end);

  /* Don't walk off the end of the function */

  stop = (stop > func_end ? func_end : stop);

  /* REGISTER_OFFSETS will contain offsets, from the top of the frame

     (NOT the frame pointer), for the various saved registers or -1

     if the register is not saved. */

  for (rn = 0; rn < NUM_REGS; rn++)

    register_offsets[rn] = -1;

  /* Analyze the prologue. Things we determine from analyzing the

     prologue include:

     * the size of the frame

     * where saved registers are located (and which are saved)

     * FP used? */

  mcore_insn_debug (("MCORE: Scanning prologue: func_addr=0x%x, stop=0x%x\n",

                     (unsigned int) func_addr, (unsigned int) stop));

  framesize = 0;

  for (addr = func_addr; addr < stop; addr += 2)

    {

      /* Get next insn */

      insn = get_insn (addr);

      mcore_dump_insn ("got 2: ", addr, insn);

      if (IS_SUBI0 (insn))

        {

          int offset = 1 + ((insn >> 4) & 0x1f);

          mcore_insn_debug (("MCORE: got subi r0,%d; continuing\n", offset));

          framesize += offset;

          continue;

        }

      else if (IS_STM (insn))

        {

          /* Spill register(s) */

          int offset;

          int start_register;

          /* BIG WARNING! The MCore ABI does not restrict functions

             to taking only one stack allocation. Therefore, when

             we save a register, we record the offset of where it was

             saved relative to the current framesize. This will

             then give an offset from the SP upon entry to our

             function. Remember, framesize is NOT constant until

             we're done scanning the prologue. */

          start_register = (insn & 0xf);

          mcore_insn_debug (("MCORE: got stm r%d-r15,(r0)\n", start_register));

          for (rn = start_register, offset = 0; rn <= 15; rn++, offset += 4)

            {

              register_offsets[rn] = framesize - offset;

              mcore_insn_debug (("MCORE: r%d saved at 0x%x (offset %d)\n", rn,

                                 register_offsets[rn], offset));

            }

          mcore_insn_debug (("MCORE: continuing\n"));

          continue;

        }

      else if (IS_STWx0 (insn))

        {

          /* Spill register: see note for IS_STM above. */

          int imm;

          rn = (insn >> 8) & 0xf;

          imm = (insn >> 4) & 0xf;

          register_offsets[rn] = framesize - (imm << 2);

          mcore_insn_debug (("MCORE: r%d saved at offset 0x%x\n", rn, register_offsets[rn]));

          mcore_insn_debug (("MCORE: continuing\n"));

          continue;

        }

      else if (IS_MOVx0 (insn))

        {

          /* We have a frame pointer, so this prologue is over.  Note

             the register which is acting as the frame pointer. */

          flags |= MY_FRAME_IN_FP;

          flags &= ~MY_FRAME_IN_SP;

          fp_regnum = insn & 0xf;

          mcore_insn_debug (("MCORE: Found a frame pointer: r%d\n", fp_regnum));

          /* If we found an FP, we're at the end of the prologue. */

          mcore_insn_debug (("MCORE: end of prologue\n"));

          if (skip_prologue)

            continue;

          /* If we're decoding prologue, stop here. */

          addr += 2;

          break;

        }

      else if (IS_STWxy (insn) && (flags & MY_FRAME_IN_FP) && ((insn & 0xf) == fp_regnum))

        {

          /* Special case. Skip over stack slot allocs, too. */

          mcore_insn_debug (("MCORE: push arg onto stack.\n"));

          continue;

        }

      else if (IS_LRW1 (insn) || IS_MOVI1 (insn)

               || IS_BGENI1 (insn) || IS_BMASKI1 (insn))

        {

          int adjust = 0;

          int offset = 0;

          int insn2;

          mcore_insn_debug (("MCORE: looking at large frame\n"));

          if (IS_LRW1 (insn))

            {

              adjust =

                read_memory_integer ((addr + 2 + ((insn & 0xff) << 2)) & 0xfffffffc, 4);

            }

          else if (IS_MOVI1 (insn))

            adjust = (insn >> 4) & 0x7f;

          else if (IS_BGENI1 (insn))

            adjust = 1 << ((insn >> 4) & 0x1f);

          else                  /* IS_BMASKI (insn) */

            adjust = (1 << (adjust >> 4) & 0x1f) - 1;

          mcore_insn_debug (("MCORE: base framesize=0x%x\n", adjust));

          /* May have zero or more insns which modify r1 */

          mcore_insn_debug (("MCORE: looking for r1 adjusters...\n"));

          offset = 2;

          insn2 = get_insn (addr + offset);

          while (IS_R1_ADJUSTER (insn2))

            {

              int imm;

              imm = (insn2 >> 4) & 0x1f;

              mcore_dump_insn ("got 3: ", addr + offset, insn);

              if (IS_ADDI1 (insn2))

                {

                  adjust += (imm + 1);

                  mcore_insn_debug (("MCORE: addi r1,%d\n", imm + 1));

                }

              else if (IS_SUBI1 (insn2))

                {

                  adjust -= (imm + 1);

                  mcore_insn_debug (("MCORE: subi r1,%d\n", imm + 1));

                }

              else if (IS_RSUBI1 (insn2))

                {

                  adjust = imm - adjust;

                  mcore_insn_debug (("MCORE: rsubi r1,%d\n", imm + 1));

                }

              else if (IS_NOT1 (insn2))

                {

                  adjust = ~adjust;

                  mcore_insn_debug (("MCORE: not r1\n"));

                }

              else if (IS_ROTLI1 (insn2))

                {

                  adjust <<= imm;

                  mcore_insn_debug (("MCORE: rotli r1,%d\n", imm + 1));

                }

              else if (IS_BSETI1 (insn2))

                {

                  adjust |= (1 << imm);

                  mcore_insn_debug (("MCORE: bseti r1,%d\n", imm));

                }

              else if (IS_BCLRI1 (insn2))

                {

                  adjust &= ~(1 << imm);

                  mcore_insn_debug (("MCORE: bclri r1,%d\n", imm));

                }

              else if (IS_IXH1 (insn2))

                {

                  adjust *= 3;

                  mcore_insn_debug (("MCORE: ix.h r1,r1\n"));

                }

              else if (IS_IXW1 (insn2))

                {

                  adjust *= 5;

                  mcore_insn_debug (("MCORE: ix.w r1,r1\n"));

                }

              offset += 2;

              insn2 = get_insn (addr + offset);

            };

          mcore_insn_debug (("MCORE: done looking for r1 adjusters\n"));

          /* If the next insn adjusts the stack pointer, we keep everything;

             if not, we scrap it and we've found the end of the prologue. */

          if (IS_SUB01 (insn2))

            {

              addr += offset;

              framesize += adjust;

              mcore_insn_debug (("MCORE: found stack adjustment of 0x%x bytes.\n", adjust));

              mcore_insn_debug (("MCORE: skipping to new address 0x%x\n", addr));

              mcore_insn_debug (("MCORE: continuing\n"));

              continue;

            }

          /* None of these instructions are prologue, so don't touch

             anything. */

          mcore_insn_debug (("MCORE: no subu r1,r0, NOT altering framesize.\n"));

          break;

        }

      /* This is not a prologue insn, so stop here. */

      mcore_insn_debug (("MCORE: insn is not a prologue insn -- ending scan\n"));

      break;

    }

  mcore_insn_debug (("MCORE: done analyzing prologue\n"));

  mcore_insn_debug (("MCORE: prologue end = 0x%x\n", addr));

  /* Save everything we have learned about this frame into FI. */

  if (fi != NULL)

    {

      fi->extra_info->framesize = framesize;

      fi->extra_info->fp_regnum = fp_regnum;

      fi->extra_info->status = flags;

      /* Fix the frame pointer. When gcc uses r8 as a frame pointer,

         it is really an arg ptr. We adjust fi->frame to be a "real"

         frame pointer. */

      if (fi->next == NULL)

        {

          if (fi->extra_info->status & MY_FRAME_IN_SP)

            fi->frame = read_sp () + framesize;

          else

            fi->frame = read_register (fp_regnum) + framesize;

        }

      /* Note where saved registers are stored. The offsets in REGISTER_OFFSETS

         are computed relative to the top of the frame. */

      for (rn = 0; rn < NUM_REGS; rn++)

        {

          if (register_offsets[rn] >= 0)

            {

              fi->saved_regs[rn] = fi->frame - register_offsets[rn];

              mcore_insn_debug (("Saved register %s stored at 0x%08x, value=0x%08x\n",

                               mcore_register_names[rn], fi->saved_regs[rn],

                              read_memory_integer (fi->saved_regs[rn], 4)));

            }

        }

    }

  /* Return addr of first non-prologue insn. */

  return addr;

}

/* Given a GDB frame, determine the address of the calling function's frame.

   This will be used to create a new GDB frame struct, and then

   INIT_EXTRA_FRAME_INFO and INIT_FRAME_PC will be called for the new frame. */

CORE_ADDR

mcore_frame_chain (struct frame_info * fi)

{

  struct frame_info *dummy;

  CORE_ADDR callers_addr;

  /* Analyze the prologue of this function. */

  if (fi->extra_info->status == 0)

    mcore_analyze_prologue (fi, 0, 0);

  /* If mcore_analyze_prologue set NO_MORE_FRAMES, quit now. */

  if (fi->extra_info->status & NO_MORE_FRAMES)

    return 0;

  /* Now that we've analyzed our prologue, we can start to ask

     for information about our caller. The easiest way to do

     this is to analyze our caller's prologue.

     If our caller has a frame pointer, then we need to find

     the value of that register upon entry to our frame.

     This value is either in fi->saved_regs[rn] if it's saved,

     or it's still in a register.

     If our caller does not have a frame pointer, then his frame base

     is <our base> + -<caller's frame size>. */

  dummy = analyze_dummy_frame (FRAME_SAVED_PC (fi), fi->frame);

  if (dummy->extra_info->status & MY_FRAME_IN_FP)

    {

      int fp = dummy->extra_info->fp_regnum;

      /* Our caller has a frame pointer. */

      if (fi->saved_regs[fp] != 0)

        {

          /* The "FP" was saved on the stack.  Don't forget to adjust

             the "FP" with the framesize to get a real FP. */

          callers_addr = read_memory_integer (fi->saved_regs[fp], REGISTER_SIZE)

            + dummy->extra_info->framesize;

        }

      else

        {

          /* It's still in the register.  Don't forget to adjust

             the "FP" with the framesize to get a real FP. */

          callers_addr = read_register (fp) + dummy->extra_info->framesize;

        }

    }

  else

    {

      /* Our caller does not have a frame pointer. */

      callers_addr = fi->frame + dummy->extra_info->framesize;

    }

  return callers_addr;

}

/* Skip the prologue of the function at PC. */

CORE_ADDR

mcore_skip_prologue (CORE_ADDR pc)

{

  CORE_ADDR func_addr, func_end;

  struct symtab_and_line sal;

  /* If we have line debugging information, then the end of the

     prologue should be the first assembly instruction of the first

     source line */

  if (find_pc_partial_function (pc, NULL, &func_addr, &func_end))

    {

      sal = find_pc_line (func_addr, 0);

      if (sal.end && sal.end < func_end)

        return sal.end;

    }

  return mcore_analyze_prologue (NULL, pc, 1);

}

/* Return the address at which function arguments are offset. */

CORE_ADDR

mcore_frame_args_address (struct frame_info * fi)

{

  return fi->frame - fi->extra_info->framesize;

}

CORE_ADDR

mcore_frame_locals_address (struct frame_info * fi)

{

  return fi->frame - fi->extra_info->framesize;

}

/* Return the frame pointer in use at address PC. */

void

mcore_virtual_frame_pointer (CORE_ADDR pc, long *reg, long *offset)

{

  struct frame_info *dummy = analyze_dummy_frame (pc, 0);

  if (dummy->extra_info->status & MY_FRAME_IN_SP)

    {

      *reg = SP_REGNUM;

      *offset = 0;

    }

  else

    {

      *reg = dummy->extra_info->fp_regnum;

      *offset = 0;

    }

}

/* Find the value of register REGNUM in frame FI. */

CORE_ADDR

mcore_find_callers_reg (struct frame_info *fi, int regnum)

{

  for (; fi != NULL; fi = fi->next)

    {

      if (PC_IN_CALL_DUMMY (fi->pc, fi->frame, fi->frame))

        return generic_read_register_dummy (fi->pc, fi->frame, regnum);

      else if (fi->saved_regs[regnum] != 0)

        return read_memory_integer (fi->saved_regs[regnum],

                                    REGISTER_SIZE);