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/* Target-machine dependent code for Motorola 88000 series, for GDB.

   Copyright 1988, 1990, 1991, 1994, 1995 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 "inferior.h"

#include "value.h"

#include "gdbcore.h"

#include "symtab.h"

#include "setjmp.h"

#include "value.h"

/* Size of an instruction */

#define BYTES_PER_88K_INSN      4

void frame_find_saved_regs ();

/* Is this target an m88110?  Otherwise assume m88100.  This has

   relevance for the ways in which we screw with instruction pointers.  */

int target_is_m88110 = 0;

/* The m88k kernel aligns all instructions on 4-byte boundaries.  The

   kernel also uses the least significant two bits for its own hocus

   pocus.  When gdb receives an address from the kernel, it needs to

   preserve those right-most two bits, but gdb also needs to be careful

   to realize that those two bits are not really a part of the address

   of an instruction.  Shrug.  */

CORE_ADDR

m88k_addr_bits_remove (addr)

     CORE_ADDR addr;

{

  return ((addr) & ~3);

}

/* 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.

   For us, the frame address is its stack pointer value, so we look up

   the function prologue to determine the caller's sp value, and return it.  */

CORE_ADDR

frame_chain (thisframe)

     struct frame_info *thisframe;

{

  frame_find_saved_regs (thisframe, (struct frame_saved_regs *) 0);

  /* NOTE:  this depends on frame_find_saved_regs returning the VALUE, not

     the ADDRESS, of SP_REGNUM.  It also depends on the cache of

     frame_find_saved_regs results.  */

  if (thisframe->fsr->regs[SP_REGNUM])

    return thisframe->fsr->regs[SP_REGNUM];

  else

    return thisframe->frame;    /* Leaf fn -- next frame up has same SP. */

}

int

frameless_function_invocation (frame)

     struct frame_info *frame;

{

  frame_find_saved_regs (frame, (struct frame_saved_regs *) 0);

  /* NOTE:  this depends on frame_find_saved_regs returning the VALUE, not

     the ADDRESS, of SP_REGNUM.  It also depends on the cache of

     frame_find_saved_regs results.  */

  if (frame->fsr->regs[SP_REGNUM])

    return 0;                    /* Frameful -- return addr saved somewhere */

  else

    return 1;                   /* Frameless -- no saved return address */

}

void

init_extra_frame_info (fromleaf, frame)

     int fromleaf;

     struct frame_info *frame;

{

  frame->fsr = 0;                /* Not yet allocated */

  frame->args_pointer = 0;       /* Unknown */

  frame->locals_pointer = 0;     /* Unknown */

}

/* Examine an m88k function prologue, recording the addresses at which

   registers are saved explicitly by the prologue code, and returning

   the address of the first instruction after the prologue (but not

   after the instruction at address LIMIT, as explained below).

   LIMIT places an upper bound on addresses of the instructions to be

   examined.  If the prologue code scan reaches LIMIT, the scan is

   aborted and LIMIT is returned.  This is used, when examining the

   prologue for the current frame, to keep examine_prologue () from

   claiming that a given register has been saved when in fact the

   instruction that saves it has not yet been executed.  LIMIT is used

   at other times to stop the scan when we hit code after the true

   function prologue (e.g. for the first source line) which might

   otherwise be mistaken for function prologue.

   The format of the function prologue matched by this routine is

   derived from examination of the source to gcc 1.95, particularly

   the routine output_prologue () in config/out-m88k.c.

   subu r31,r31,n                       # stack pointer update

   (st rn,r31,offset)?                  # save incoming regs

   (st.d rn,r31,offset)?

   (addu r30,r31,n)?                    # frame pointer update

   (pic sequence)?                      # PIC code prologue

   (or   rn,rm,0)?                      # Move parameters to other regs

 */

/* Macros for extracting fields from instructions.  */

#define BITMASK(pos, width) (((0x1 << (width)) - 1) << (pos))

#define EXTRACT_FIELD(val, pos, width) ((val) >> (pos) & BITMASK (0, width))

#define SUBU_OFFSET(x)  ((unsigned)(x & 0xFFFF))

#define ST_OFFSET(x)    ((unsigned)((x) & 0xFFFF))

#define ST_SRC(x)       EXTRACT_FIELD ((x), 21, 5)

#define ADDU_OFFSET(x)  ((unsigned)(x & 0xFFFF))

/*

 * prologue_insn_tbl is a table of instructions which may comprise a

 * function prologue.  Associated with each table entry (corresponding

 * to a single instruction or group of instructions), is an action.

 * This action is used by examine_prologue (below) to determine

 * the state of certain machine registers and where the stack frame lives.

 */

enum prologue_insn_action

{

  PIA_SKIP,                     /* don't care what the instruction does */

  PIA_NOTE_ST,                  /* note register stored and where */

  PIA_NOTE_STD,                 /* note pair of registers stored and where */

  PIA_NOTE_SP_ADJUSTMENT,       /* note stack pointer adjustment */

  PIA_NOTE_FP_ASSIGNMENT,       /* note frame pointer assignment */

  PIA_NOTE_PROLOGUE_END,        /* no more prologue */

};

struct prologue_insns

  {

    unsigned long insn;

    unsigned long mask;

    enum prologue_insn_action action;

  };

struct prologue_insns prologue_insn_tbl[] =

{

  /* Various register move instructions */

  {0x58000000, 0xf800ffff, PIA_SKIP},   /* or/or.u with immed of 0 */

  {0xf4005800, 0xfc1fffe0, PIA_SKIP},   /* or rd, r0, rs */

  {0xf4005800, 0xfc00ffff, PIA_SKIP},   /* or rd, rs, r0 */

  /* Stack pointer setup: "subu sp, sp, n" where n is a multiple of 8 */

  {0x67ff0000, 0xffff0007, PIA_NOTE_SP_ADJUSTMENT},

  /* Frame pointer assignment: "addu r30, r31, n" */

  {0x63df0000, 0xffff0000, PIA_NOTE_FP_ASSIGNMENT},

  /* Store to stack instructions; either "st rx, sp, n" or "st.d rx, sp, n" */

  {0x241f0000, 0xfc1f0000, PIA_NOTE_ST},        /* st rx, sp, n */

  {0x201f0000, 0xfc1f0000, PIA_NOTE_STD},       /* st.d rs, sp, n */

  /* Instructions needed for setting up r25 for pic code. */

  {0x5f200000, 0xffff0000, PIA_SKIP},   /* or.u r25, r0, offset_high */

  {0xcc000002, 0xffffffff, PIA_SKIP},   /* bsr.n Lab */

  {0x5b390000, 0xffff0000, PIA_SKIP},   /* or r25, r25, offset_low */

  {0xf7396001, 0xffffffff, PIA_SKIP},   /* Lab: addu r25, r25, r1 */

  /* Various branch or jump instructions which have a delay slot -- these

     do not form part of the prologue, but the instruction in the delay

     slot might be a store instruction which should be noted. */

  {0xc4000000, 0xe4000000, PIA_NOTE_PROLOGUE_END},

                                        /* br.n, bsr.n, bb0.n, or bb1.n */

  {0xec000000, 0xfc000000, PIA_NOTE_PROLOGUE_END},      /* bcnd.n */

  {0xf400c400, 0xfffff7e0, PIA_NOTE_PROLOGUE_END}       /* jmp.n or jsr.n */

};

/* Fetch the instruction at ADDR, returning 0 if ADDR is beyond LIM or

   is not the address of a valid instruction, the address of the next

   instruction beyond ADDR otherwise.  *PWORD1 receives the first word

   of the instruction. */

#define NEXT_PROLOGUE_INSN(addr, lim, pword1) \

  (((addr) < (lim)) ? next_insn (addr, pword1) : 0)

/* Read the m88k instruction at 'memaddr' and return the address of

   the next instruction after that, or 0 if 'memaddr' is not the

   address of a valid instruction.  The instruction

   is stored at 'pword1'.  */

CORE_ADDR

next_insn (memaddr, pword1)

     unsigned long *pword1;

     CORE_ADDR memaddr;

{

  *pword1 = read_memory_integer (memaddr, BYTES_PER_88K_INSN);

  return memaddr + BYTES_PER_88K_INSN;

}

/* Read a register from frames called by us (or from the hardware regs).  */

static int

read_next_frame_reg (frame, regno)

     struct frame_info *frame;

     int regno;

{

  for (; frame; frame = frame->next)

    {

      if (regno == SP_REGNUM)

        return FRAME_FP (frame);

      else if (frame->fsr->regs[regno])

        return read_memory_integer (frame->fsr->regs[regno], 4);

    }

  return read_register (regno);

}

/* Examine the prologue of a function.  `ip' points to the first instruction.

   `limit' is the limit of the prologue (e.g. the addr of the first

   linenumber, or perhaps the program counter if we're stepping through).

   `frame_sp' is the stack pointer value in use in this frame.

   `fsr' is a pointer to a frame_saved_regs structure into which we put

   info about the registers saved by this frame.

   `fi' is a struct frame_info pointer; we fill in various fields in it

   to reflect the offsets of the arg pointer and the locals pointer.  */

static CORE_ADDR

examine_prologue (ip, limit, frame_sp, fsr, fi)

     register CORE_ADDR ip;

     register CORE_ADDR limit;

     CORE_ADDR frame_sp;

     struct frame_saved_regs *fsr;

     struct frame_info *fi;

{

  register CORE_ADDR next_ip;

  register int src;

  unsigned int insn;

  int size, offset;

  char must_adjust[32];         /* If set, must adjust offsets in fsr */

  int sp_offset = -1;           /* -1 means not set (valid must be mult of 8) */

  int fp_offset = -1;           /* -1 means not set */

  CORE_ADDR frame_fp;

  CORE_ADDR prologue_end = 0;

  memset (must_adjust, '\0', sizeof (must_adjust));

  next_ip = NEXT_PROLOGUE_INSN (ip, limit, &insn);

  while (next_ip)

    {

      struct prologue_insns *pip;

      for (pip = prologue_insn_tbl; (insn & pip->mask) != pip->insn;)

        if (++pip >= prologue_insn_tbl + sizeof prologue_insn_tbl)

          goto end_of_prologue_found;   /* not a prologue insn */

      switch (pip->action)

        {

        case PIA_NOTE_ST:

        case PIA_NOTE_STD:

          if (sp_offset != -1)

            {

              src = ST_SRC (insn);

              offset = ST_OFFSET (insn);

              must_adjust[src] = 1;

              fsr->regs[src++] = offset;        /* Will be adjusted later */

              if (pip->action == PIA_NOTE_STD && src < 32)

                {

                  offset += 4;

                  must_adjust[src] = 1;

                  fsr->regs[src++] = offset;

                }

            }

          else

            goto end_of_prologue_found;

          break;

        case PIA_NOTE_SP_ADJUSTMENT:

          if (sp_offset == -1)

            sp_offset = -SUBU_OFFSET (insn);

          else

            goto end_of_prologue_found;

          break;

        case PIA_NOTE_FP_ASSIGNMENT:

          if (fp_offset == -1)

            fp_offset = ADDU_OFFSET (insn);

          else

            goto end_of_prologue_found;

          break;

        case PIA_NOTE_PROLOGUE_END:

          if (!prologue_end)

            prologue_end = ip;

          break;

        case PIA_SKIP:

        default:

          /* Do nothing */

          break;

        }

      ip = next_ip;

      next_ip = NEXT_PROLOGUE_INSN (ip, limit, &insn);

    }

end_of_prologue_found:

  if (prologue_end)

    ip = prologue_end;

  /* We're done with the prologue.  If we don't care about the stack

     frame itself, just return.  (Note that fsr->regs has been trashed,

     but the one caller who calls with fi==0 passes a dummy there.)  */

  if (fi == 0)

    return ip;

  /*

     OK, now we have:

     sp_offset  original (before any alloca calls) displacement of SP

     (will be negative).

     fp_offset  displacement from original SP to the FP for this frame

     or -1.

     fsr->regs[0..31]   displacement from original SP to the stack

     location where reg[0..31] is stored.

     must_adjust[0..31] set if corresponding offset was set.

     If alloca has been called between the function prologue and the current

     IP, then the current SP (frame_sp) will not be the original SP as set by

     the function prologue.  If the current SP is not the original SP, then the

     compiler will have allocated an FP for this frame, fp_offset will be set,

     and we can use it to calculate the original SP.

     Then, we figure out where the arguments and locals are, and relocate the

     offsets in fsr->regs to absolute addresses.  */

  if (fp_offset != -1)

    {

      /* We have a frame pointer, so get it, and base our calc's on it.  */

      frame_fp = (CORE_ADDR) read_next_frame_reg (fi->next, ACTUAL_FP_REGNUM);

      frame_sp = frame_fp - fp_offset;

    }

  else

    {

      /* We have no frame pointer, therefore frame_sp is still the same value

         as set by prologue.  But where is the frame itself?  */

      if (must_adjust[SRP_REGNUM])

        {

          /* Function header saved SRP (r1), the return address.  Frame starts

             4 bytes down from where it was saved.  */

          frame_fp = frame_sp + fsr->regs[SRP_REGNUM] - 4;

          fi->locals_pointer = frame_fp;

        }

      else

        {

          /* Function header didn't save SRP (r1), so we are in a leaf fn or

             are otherwise confused.  */

          frame_fp = -1;

        }

    }

  /* The locals are relative to the FP (whether it exists as an allocated

     register, or just as an assumed offset from the SP) */

  fi->locals_pointer = frame_fp;

  /* The arguments are just above the SP as it was before we adjusted it

     on entry.  */

  fi->args_pointer = frame_sp - sp_offset;

  /* Now that we know the SP value used by the prologue, we know where

     it saved all the registers.  */

  for (src = 0; src < 32; src++)

    if (must_adjust[src])

      fsr->regs[src] += frame_sp;

  /* The saved value of the SP is always known.  */

  /* (we hope...) */

  if (fsr->regs[SP_REGNUM] != 0

      && fsr->regs[SP_REGNUM] != frame_sp - sp_offset)

    fprintf_unfiltered (gdb_stderr, "Bad saved SP value %x != %x, offset %x!\n",

                        fsr->regs[SP_REGNUM],

                        frame_sp - sp_offset, sp_offset);

  fsr->regs[SP_REGNUM] = frame_sp - sp_offset;

  return (ip);

}

/* Given an ip value corresponding to the start of a function,

   return the ip of the first instruction after the function

   prologue.  */

CORE_ADDR

m88k_skip_prologue (ip)

CORE_ADDR (ip);

{

  struct frame_saved_regs saved_regs_dummy;

  struct symtab_and_line sal;

  CORE_ADDR limit;

  sal = find_pc_line (ip, 0);

  limit = (sal.end) ? sal.end : 0xffffffff;

  return (examine_prologue (ip, limit, (CORE_ADDR) 0, &saved_regs_dummy,

                            (struct frame_info *) 0));

}

/* Put here the code to store, into a struct frame_saved_regs,

   the addresses of the saved registers of frame described by FRAME_INFO.

   This includes special registers such as pc and fp saved in special

   ways in the stack frame.  sp is even more special:

   the address we return for it IS the sp for the next frame.

   We cache the result of doing this in the frame_obstack, since it is

   fairly expensive.  */

void

frame_find_saved_regs (fi, fsr)

     struct frame_info *fi;

     struct frame_saved_regs *fsr;

{

  register struct frame_saved_regs *cache_fsr;

  CORE_ADDR ip;

  struct symtab_and_line sal;

  CORE_ADDR limit;

  if (!fi->fsr)

    {

      cache_fsr = (struct frame_saved_regs *)

        frame_obstack_alloc (sizeof (struct frame_saved_regs));

      memset (cache_fsr, '\0', sizeof (struct frame_saved_regs));

      fi->fsr = cache_fsr;

      /* Find the start and end of the function prologue.  If the PC

         is in the function prologue, we only consider the part that

         has executed already.  In the case where the PC is not in

         the function prologue, we set limit to two instructions beyond

         where the prologue ends in case if any of the prologue instructions

         were moved into a delay slot of a branch instruction. */

      ip = get_pc_function_start (fi->pc);

      sal = find_pc_line (ip, 0);

      limit = (sal.end && sal.end < fi->pc) ? sal.end + 2 * BYTES_PER_88K_INSN

        : fi->pc;

      /* This will fill in fields in *fi as well as in cache_fsr.  */

#ifdef SIGTRAMP_FRAME_FIXUP

      if (fi->signal_handler_caller)

        SIGTRAMP_FRAME_FIXUP (fi->frame);

#endif

      examine_prologue (ip, limit, fi->frame, cache_fsr, fi);

#ifdef SIGTRAMP_SP_FIXUP

      if (fi->signal_handler_caller && fi->fsr->regs[SP_REGNUM])

        SIGTRAMP_SP_FIXUP (fi->fsr->regs[SP_REGNUM]);

#endif

    }

  if (fsr)

    *fsr = *fi->fsr;

}

/* Return the address of the locals block for the frame

   described by FI.  Returns 0 if the address is unknown.

   NOTE!  Frame locals are referred to by negative offsets from the

   argument pointer, so this is the same as frame_args_address().  */

CORE_ADDR

frame_locals_address (fi)

     struct frame_info *fi;

{

  struct frame_saved_regs fsr;

  if (fi->args_pointer)         /* Cached value is likely there.  */

    return fi->args_pointer;

  /* Nope, generate it.  */

  get_frame_saved_regs (fi, &fsr);

  return fi->args_pointer;

}

/* Return the address of the argument block for the frame

   described by FI.  Returns 0 if the address is unknown.  */

CORE_ADDR

frame_args_address (fi)

     struct frame_info *fi;

{

  struct frame_saved_regs fsr;

  if (fi->args_pointer)         /* Cached value is likely there.  */

    return fi->args_pointer;

  /* Nope, generate it.  */

  get_frame_saved_regs (fi, &fsr);

  return fi->args_pointer;

}

/* Return the saved PC from this frame.

   If the frame has a memory copy of SRP_REGNUM, use that.  If not,

   just use the register SRP_REGNUM itself.  */

CORE_ADDR

frame_saved_pc (frame)

     struct frame_info *frame;

{

  return read_next_frame_reg (frame, SRP_REGNUM);

}

#define DUMMY_FRAME_SIZE 192

static void

write_word (sp, word)

     CORE_ADDR sp;

     ULONGEST word;

{

  register int len = REGISTER_SIZE;

  char buffer[MAX_REGISTER_RAW_SIZE];

  store_unsigned_integer (buffer, len, word);

  write_memory (sp, buffer, len);

}

void

m88k_push_dummy_frame ()

{

  register CORE_ADDR sp = read_register (SP_REGNUM);

  register int rn;

  int offset;

  sp -= DUMMY_FRAME_SIZE;       /* allocate a bunch of space */

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

    write_word (sp + offset, read_register (rn));

  write_word (sp + offset, read_register (SXIP_REGNUM));

  offset += 4;

  write_word (sp + offset, read_register (SNIP_REGNUM));

  offset += 4;

  write_word (sp + offset, read_register (SFIP_REGNUM));

  offset += 4;

  write_word (sp + offset, read_register (PSR_REGNUM));

  offset += 4;

  write_word (sp + offset, read_register (FPSR_REGNUM));

  offset += 4;

  write_word (sp + offset, read_register (FPCR_REGNUM));

  offset += 4;

  write_register (SP_REGNUM, sp);

  write_register (ACTUAL_FP_REGNUM, sp);

}

void

pop_frame ()

{

  register struct frame_info *frame = get_current_frame ();

  register CORE_ADDR fp;

  register int regnum;

  struct frame_saved_regs fsr;

  fp = FRAME_FP (frame);

  get_frame_saved_regs (frame, &fsr);

  if (PC_IN_CALL_DUMMY (read_pc (), read_register (SP_REGNUM), FRAME_FP (fi)))

    {

      /* FIXME: I think get_frame_saved_regs should be handling this so

         that we can deal with the saved registers properly (e.g. frame

         1 is a call dummy, the user types "frame 2" and then "print $ps").  */

      register CORE_ADDR sp = read_register (ACTUAL_FP_REGNUM);

      int offset;

      for (regnum = 0, offset = 0; regnum <= SP_REGNUM; regnum++, offset += 4)

        (void) write_register (regnum, read_memory_integer (sp + offset, 4));

      write_register (SXIP_REGNUM, read_memory_integer (sp + offset, 4));

      offset += 4;

      write_register (SNIP_REGNUM, read_memory_integer (sp + offset, 4));

      offset += 4;

      write_register (SFIP_REGNUM, read_memory_integer (sp + offset, 4));

      offset += 4;

      write_register (PSR_REGNUM, read_memory_integer (sp + offset, 4));

      offset += 4;

      write_register (FPSR_REGNUM, read_memory_integer (sp + offset, 4));

      offset += 4;

      write_register (FPCR_REGNUM, read_memory_integer (sp + offset, 4));

      offset += 4;

    }

  else

    {

      for (regnum = FP_REGNUM; regnum > 0; regnum--)

        if (fsr.regs[regnum])

          write_register (regnum,

                          read_memory_integer (fsr.regs[regnum], 4));

      write_pc (frame_saved_pc (frame));

    }

  reinit_frame_cache ();

}

void

_initialize_m88k_tdep ()

{

  tm_print_insn = print_insn_m88k;

}