path: root/gdb/rs6000-tdep.c

/* Target-dependent code for GDB, the GNU debugger.
   Copyright 1986, 1987, 1989, 1991, 1992, 1993, 1994, 1995, 1996, 1997,
   1998, 1999, 2000, 2001, 2002, 2003
   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 "symtab.h"
#include "target.h"
#include "gdbcore.h"
#include "gdbcmd.h"
#include "symfile.h"
#include "objfiles.h"
#include "arch-utils.h"
#include "regcache.h"
#include "doublest.h"
#include "value.h"
#include "parser-defs.h"
#include "osabi.h"

#include "libbfd.h"		/* for bfd_default_set_arch_mach */
#include "coff/internal.h"	/* for libcoff.h */
#include "libcoff.h"		/* for xcoff_data */
#include "coff/xcoff.h"
#include "libxcoff.h"

#include "elf-bfd.h"

#include "solib-svr4.h"
#include "ppc-tdep.h"

#include "gdb_assert.h"

/* If the kernel has to deliver a signal, it pushes a sigcontext
   structure on the stack and then calls the signal handler, passing
   the address of the sigcontext in an argument register. Usually
   the signal handler doesn't save this register, so we have to
   access the sigcontext structure via an offset from the signal handler
   frame.
   The following constants were determined by experimentation on AIX 3.2.  */
#define SIG_FRAME_PC_OFFSET 96
#define SIG_FRAME_LR_OFFSET 108
#define SIG_FRAME_FP_OFFSET 284

/* To be used by skip_prologue. */

struct rs6000_framedata
  {
    int offset;			/* total size of frame --- the distance
				   by which we decrement sp to allocate
				   the frame */
    int saved_gpr;		/* smallest # of saved gpr */
    int saved_fpr;		/* smallest # of saved fpr */
    int saved_vr;               /* smallest # of saved vr */
    int saved_ev;               /* smallest # of saved ev */
    int alloca_reg;		/* alloca register number (frame ptr) */
    char frameless;		/* true if frameless functions. */
    char nosavedpc;		/* true if pc not saved. */
    int gpr_offset;		/* offset of saved gprs from prev sp */
    int fpr_offset;		/* offset of saved fprs from prev sp */
    int vr_offset;              /* offset of saved vrs from prev sp */
    int ev_offset;              /* offset of saved evs from prev sp */
    int lr_offset;		/* offset of saved lr */
    int cr_offset;		/* offset of saved cr */
    int vrsave_offset;          /* offset of saved vrsave register */
  };

/* Description of a single register. */

struct reg
  {
    char *name;			/* name of register */
    unsigned char sz32;		/* size on 32-bit arch, 0 if nonextant */
    unsigned char sz64;		/* size on 64-bit arch, 0 if nonextant */
    unsigned char fpr;		/* whether register is floating-point */
    unsigned char pseudo;       /* whether register is pseudo */
  };

/* Breakpoint shadows for the single step instructions will be kept here. */

static struct sstep_breaks
  {
    /* Address, or 0 if this is not in use.  */
    CORE_ADDR address;
    /* Shadow contents.  */
    char data[4];
  }
stepBreaks[2];

/* Hook for determining the TOC address when calling functions in the
   inferior under AIX. The initialization code in rs6000-nat.c sets
   this hook to point to find_toc_address.  */

CORE_ADDR (*rs6000_find_toc_address_hook) (CORE_ADDR) = NULL;

/* Hook to set the current architecture when starting a child process. 
   rs6000-nat.c sets this. */

void (*rs6000_set_host_arch_hook) (int) = NULL;

/* Static function prototypes */

static CORE_ADDR branch_dest (int opcode, int instr, CORE_ADDR pc,
			      CORE_ADDR safety);
static CORE_ADDR skip_prologue (CORE_ADDR, CORE_ADDR,
                                struct rs6000_framedata *);
static void frame_get_saved_regs (struct frame_info * fi,
				  struct rs6000_framedata * fdatap);
static CORE_ADDR frame_initial_stack_address (struct frame_info *);

/* Is REGNO an AltiVec register?  Return 1 if so, 0 otherwise.  */
int
altivec_register_p (int regno)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
  if (tdep->ppc_vr0_regnum < 0 || tdep->ppc_vrsave_regnum < 0)
    return 0;
  else
    return (regno >= tdep->ppc_vr0_regnum && regno <= tdep->ppc_vrsave_regnum);
}

/* Read a LEN-byte address from debugged memory address MEMADDR. */

static CORE_ADDR
read_memory_addr (CORE_ADDR memaddr, int len)
{
  return read_memory_unsigned_integer (memaddr, len);
}

static CORE_ADDR
rs6000_skip_prologue (CORE_ADDR pc)
{
  struct rs6000_framedata frame;
  pc = skip_prologue (pc, 0, &frame);
  return pc;
}


/* Fill in fi->saved_regs */

struct frame_extra_info
{
  /* Functions calling alloca() change the value of the stack
     pointer. We need to use initial stack pointer (which is saved in
     r31 by gcc) in such cases. If a compiler emits traceback table,
     then we should use the alloca register specified in traceback
     table. FIXME. */
  CORE_ADDR initial_sp;		/* initial stack pointer. */
};

void
rs6000_init_extra_frame_info (int fromleaf, struct frame_info *fi)
{
  struct frame_extra_info *extra_info =
    frame_extra_info_zalloc (fi, sizeof (struct frame_extra_info));
  extra_info->initial_sp = 0;
  if (get_next_frame (fi) != NULL
      && get_frame_pc (fi) < TEXT_SEGMENT_BASE)
    /* We're in get_prev_frame */
    /* and this is a special signal frame.  */
    /* (fi->pc will be some low address in the kernel, */
    /*  to which the signal handler returns).  */
    deprecated_set_frame_type (fi, SIGTRAMP_FRAME);
}

/* 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.  */

/* In this implementation for RS/6000, we do *not* save sp. I am
   not sure if it will be needed. The following function takes care of gpr's
   and fpr's only. */

void
rs6000_frame_init_saved_regs (struct frame_info *fi)
{
  frame_get_saved_regs (fi, NULL);
}

static CORE_ADDR
rs6000_frame_args_address (struct frame_info *fi)
{
  struct frame_extra_info *extra_info = get_frame_extra_info (fi);
  if (extra_info->initial_sp != 0)
    return extra_info->initial_sp;
  else
    return frame_initial_stack_address (fi);
}

/* Immediately after a function call, return the saved pc.
   Can't go through the frames for this because on some machines
   the new frame is not set up until the new function executes
   some instructions.  */

static CORE_ADDR
rs6000_saved_pc_after_call (struct frame_info *fi)
{
  return read_register (gdbarch_tdep (current_gdbarch)->ppc_lr_regnum);
}

/* Calculate the destination of a branch/jump.  Return -1 if not a branch.  */

static CORE_ADDR
branch_dest (int opcode, int instr, CORE_ADDR pc, CORE_ADDR safety)
{
  CORE_ADDR dest;
  int immediate;
  int absolute;
  int ext_op;

  absolute = (int) ((instr >> 1) & 1);

  switch (opcode)
    {
    case 18:
      immediate = ((instr & ~3) << 6) >> 6;	/* br unconditional */
      if (absolute)
	dest = immediate;
      else
	dest = pc + immediate;
      break;

    case 16:
      immediate = ((instr & ~3) << 16) >> 16;	/* br conditional */
      if (absolute)
	dest = immediate;
      else
	dest = pc + immediate;
      break;

    case 19:
      ext_op = (instr >> 1) & 0x3ff;

      if (ext_op == 16)		/* br conditional register */
	{
          dest = read_register (gdbarch_tdep (current_gdbarch)->ppc_lr_regnum) & ~3;

	  /* If we are about to return from a signal handler, dest is
	     something like 0x3c90.  The current frame is a signal handler
	     caller frame, upon completion of the sigreturn system call
	     execution will return to the saved PC in the frame.  */
	  if (dest < TEXT_SEGMENT_BASE)
	    {
	      struct frame_info *fi;

	      fi = get_current_frame ();
	      if (fi != NULL)
		dest = read_memory_addr (get_frame_base (fi) + SIG_FRAME_PC_OFFSET,
					 gdbarch_tdep (current_gdbarch)->wordsize);
	    }
	}

      else if (ext_op == 528)	/* br cond to count reg */
	{
          dest = read_register (gdbarch_tdep (current_gdbarch)->ppc_ctr_regnum) & ~3;

	  /* If we are about to execute a system call, dest is something
	     like 0x22fc or 0x3b00.  Upon completion the system call
	     will return to the address in the link register.  */
	  if (dest < TEXT_SEGMENT_BASE)
            dest = read_register (gdbarch_tdep (current_gdbarch)->ppc_lr_regnum) & ~3;
	}
      else
	return -1;
      break;

    default:
      return -1;
    }
  return (dest < TEXT_SEGMENT_BASE) ? safety : dest;
}


/* Sequence of bytes for breakpoint instruction.  */

#define BIG_BREAKPOINT { 0x7d, 0x82, 0x10, 0x08 }
#define LITTLE_BREAKPOINT { 0x08, 0x10, 0x82, 0x7d }

const static unsigned char *
rs6000_breakpoint_from_pc (CORE_ADDR *bp_addr, int *bp_size)
{
  static unsigned char big_breakpoint[] = BIG_BREAKPOINT;
  static unsigned char little_breakpoint[] = LITTLE_BREAKPOINT;
  *bp_size = 4;
  if (TARGET_BYTE_ORDER == BFD_ENDIAN_BIG)
    return big_breakpoint;
  else
    return little_breakpoint;
}


/* AIX does not support PT_STEP. Simulate it. */

void
rs6000_software_single_step (enum target_signal signal,
			     int insert_breakpoints_p)
{
  CORE_ADDR dummy;
  int breakp_sz;
  const char *breakp = rs6000_breakpoint_from_pc (&dummy, &breakp_sz);
  int ii, insn;
  CORE_ADDR loc;
  CORE_ADDR breaks[2];
  int opcode;

  if (insert_breakpoints_p)
    {

      loc = read_pc ();

      insn = read_memory_integer (loc, 4);

      breaks[0] = loc + breakp_sz;
      opcode = insn >> 26;
      breaks[1] = branch_dest (opcode, insn, loc, breaks[0]);

      /* Don't put two breakpoints on the same address. */
      if (breaks[1] == breaks[0])
	breaks[1] = -1;

      stepBreaks[1].address = 0;

      for (ii = 0; ii < 2; ++ii)
	{

	  /* ignore invalid breakpoint. */
	  if (breaks[ii] == -1)
	    continue;
	  target_insert_breakpoint (breaks[ii], stepBreaks[ii].data);
	  stepBreaks[ii].address = breaks[ii];
	}

    }
  else
    {

      /* remove step breakpoints. */
      for (ii = 0; ii < 2; ++ii)
	if (stepBreaks[ii].address != 0)
	  target_remove_breakpoint (stepBreaks[ii].address,
				    stepBreaks[ii].data);
    }
  errno = 0;			/* FIXME, don't ignore errors! */
  /* What errors?  {read,write}_memory call error().  */
}


/* return pc value after skipping a function prologue and also return
   information about a function frame.

   in struct rs6000_framedata fdata:
   - frameless is TRUE, if function does not have a frame.
   - nosavedpc is TRUE, if function does not save %pc value in its frame.
   - offset is the initial size of this stack frame --- the amount by
   which we decrement the sp to allocate the frame.
   - saved_gpr is the number of the first saved gpr.
   - saved_fpr is the number of the first saved fpr.
   - saved_vr is the number of the first saved vr.
   - saved_ev is the number of the first saved ev.
   - alloca_reg is the number of the register used for alloca() handling.
   Otherwise -1.
   - gpr_offset is the offset of the first saved gpr from the previous frame.
   - fpr_offset is the offset of the first saved fpr from the previous frame.
   - vr_offset is the offset of the first saved vr from the previous frame.
   - ev_offset is the offset of the first saved ev from the previous frame.
   - lr_offset is the offset of the saved lr
   - cr_offset is the offset of the saved cr
   - vrsave_offset is the offset of the saved vrsave register
 */

#define SIGNED_SHORT(x) 						\
  ((sizeof (short) == 2)						\
   ? ((int)(short)(x))							\
   : ((int)((((x) & 0xffff) ^ 0x8000) - 0x8000)))

#define GET_SRC_REG(x) (((x) >> 21) & 0x1f)

/* Limit the number of skipped non-prologue instructions, as the examining
   of the prologue is expensive.  */
static int max_skip_non_prologue_insns = 10;

/* Given PC representing the starting address of a function, and
   LIM_PC which is the (sloppy) limit to which to scan when looking
   for a prologue, attempt to further refine this limit by using
   the line data in the symbol table.  If successful, a better guess
   on where the prologue ends is returned, otherwise the previous
   value of lim_pc is returned.  */
static CORE_ADDR
refine_prologue_limit (CORE_ADDR pc, CORE_ADDR lim_pc)
{
  struct symtab_and_line prologue_sal;

  prologue_sal = find_pc_line (pc, 0);
  if (prologue_sal.line != 0)
    {
      int i;
      CORE_ADDR addr = prologue_sal.end;

      /* Handle the case in which compiler's optimizer/scheduler
         has moved instructions into the prologue.  We scan ahead
	 in the function looking for address ranges whose corresponding
	 line number is less than or equal to the first one that we
	 found for the function.  (It can be less than when the
	 scheduler puts a body instruction before the first prologue
	 instruction.)  */
      for (i = 2 * max_skip_non_prologue_insns; 
           i > 0 && (lim_pc == 0 || addr < lim_pc);
	   i--)
        {
	  struct symtab_and_line sal;

	  sal = find_pc_line (addr, 0);
	  if (sal.line == 0)
	    break;
	  if (sal.line <= prologue_sal.line 
	      && sal.symtab == prologue_sal.symtab)
	    {
	      prologue_sal = sal;
	    }
	  addr = sal.end;
	}

      if (lim_pc == 0 || prologue_sal.end < lim_pc)
	lim_pc = prologue_sal.end;
    }
  return lim_pc;
}


static CORE_ADDR
skip_prologue (CORE_ADDR pc, CORE_ADDR lim_pc, struct rs6000_framedata *fdata)
{
  CORE_ADDR orig_pc = pc;
  CORE_ADDR last_prologue_pc = pc;
  CORE_ADDR li_found_pc = 0;
  char buf[4];
  unsigned long op;
  long offset = 0;
  long vr_saved_offset = 0;
  int lr_reg = -1;
  int cr_reg = -1;
  int vr_reg = -1;
  int ev_reg = -1;
  long ev_offset = 0;
  int vrsave_reg = -1;
  int reg;
  int framep = 0;
  int minimal_toc_loaded = 0;
  int prev_insn_was_prologue_insn = 1;
  int num_skip_non_prologue_insns = 0;
  const struct bfd_arch_info *arch_info = gdbarch_bfd_arch_info (current_gdbarch);
  struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
  
  /* Attempt to find the end of the prologue when no limit is specified.
     Note that refine_prologue_limit() has been written so that it may
     be used to "refine" the limits of non-zero PC values too, but this
     is only safe if we 1) trust the line information provided by the
     compiler and 2) iterate enough to actually find the end of the
     prologue.  
     
     It may become a good idea at some point (for both performance and
     accuracy) to unconditionally call refine_prologue_limit().  But,
     until we can make a clear determination that this is beneficial,
     we'll play it safe and only use it to obtain a limit when none
     has been specified.  */
  if (lim_pc == 0)
    lim_pc = refine_prologue_limit (pc, lim_pc);

  memset (fdata, 0, sizeof (struct rs6000_framedata));
  fdata->saved_gpr = -1;
  fdata->saved_fpr = -1;
  fdata->saved_vr = -1;
  fdata->saved_ev = -1;
  fdata->alloca_reg = -1;
  fdata->frameless = 1;
  fdata->nosavedpc = 1;

  for (;; pc += 4)
    {
      /* Sometimes it isn't clear if an instruction is a prologue
         instruction or not.  When we encounter one of these ambiguous
	 cases, we'll set prev_insn_was_prologue_insn to 0 (false).
	 Otherwise, we'll assume that it really is a prologue instruction. */
      if (prev_insn_was_prologue_insn)
	last_prologue_pc = pc;

      /* Stop scanning if we've hit the limit.  */
      if (lim_pc != 0 && pc >= lim_pc)
	break;

      prev_insn_was_prologue_insn = 1;

      /* Fetch the instruction and convert it to an integer.  */
      if (target_read_memory (pc, buf, 4))
	break;
      op = extract_signed_integer (buf, 4);

      if ((op & 0xfc1fffff) == 0x7c0802a6)
	{			/* mflr Rx */
	  lr_reg = (op & 0x03e00000) | 0x90010000;
	  continue;

	}
      else if ((op & 0xfc1fffff) == 0x7c000026)
	{			/* mfcr Rx */
	  cr_reg = (op & 0x03e00000) | 0x90010000;
	  continue;

	}
      else if ((op & 0xfc1f0000) == 0xd8010000)
	{			/* stfd Rx,NUM(r1) */
	  reg = GET_SRC_REG (op);
	  if (fdata->saved_fpr == -1 || fdata->saved_fpr > reg)
	    {
	      fdata->saved_fpr = reg;
	      fdata->fpr_offset = SIGNED_SHORT (op) + offset;
	    }
	  continue;

	}
      else if (((op & 0xfc1f0000) == 0xbc010000) ||	/* stm Rx, NUM(r1) */
	       (((op & 0xfc1f0000) == 0x90010000 ||	/* st rx,NUM(r1) */
		 (op & 0xfc1f0003) == 0xf8010000) &&	/* std rx,NUM(r1) */
		(op & 0x03e00000) >= 0x01a00000))	/* rx >= r13 */
	{

	  reg = GET_SRC_REG (op);
	  if (fdata->saved_gpr == -1 || fdata->saved_gpr > reg)
	    {
	      fdata->saved_gpr = reg;
	      if ((op & 0xfc1f0003) == 0xf8010000)
		op = (op >> 1) << 1;
	      fdata->gpr_offset = SIGNED_SHORT (op) + offset;
	    }
	  continue;

	}
      else if ((op & 0xffff0000) == 0x60000000)
        {
	  /* nop */
	  /* Allow nops in the prologue, but do not consider them to
	     be part of the prologue unless followed by other prologue
	     instructions. */
	  prev_insn_was_prologue_insn = 0;
	  continue;

	}
      else if ((op & 0xffff0000) == 0x3c000000)
	{			/* addis 0,0,NUM, used
				   for >= 32k frames */
	  fdata->offset = (op & 0x0000ffff) << 16;
	  fdata->frameless = 0;
	  continue;

	}
      else if ((op & 0xffff0000) == 0x60000000)
	{			/* ori 0,0,NUM, 2nd ha
				   lf of >= 32k frames */
	  fdata->offset |= (op & 0x0000ffff);
	  fdata->frameless = 0;
	  continue;

	}
      else if (lr_reg != -1 && (op & 0xffff0000) == lr_reg)
	{			/* st Rx,NUM(r1) 
				   where Rx == lr */
	  fdata->lr_offset = SIGNED_SHORT (op) + offset;
	  fdata->nosavedpc = 0;
	  lr_reg = 0;
	  continue;

	}
      else if (cr_reg != -1 && (op & 0xffff0000) == cr_reg)
	{			/* st Rx,NUM(r1) 
				   where Rx == cr */
	  fdata->cr_offset = SIGNED_SHORT (op) + offset;
	  cr_reg = 0;
	  continue;

	}
      else if (op == 0x48000005)
	{			/* bl .+4 used in 
				   -mrelocatable */
	  continue;

	}
      else if (op == 0x48000004)
	{			/* b .+4 (xlc) */
	  break;

	}
      else if ((op & 0xffff0000) == 0x3fc00000 ||  /* addis 30,0,foo@ha, used
						      in V.4 -mminimal-toc */
	       (op & 0xffff0000) == 0x3bde0000)
	{			/* addi 30,30,foo@l */
	  continue;

	}
      else if ((op & 0xfc000001) == 0x48000001)
	{			/* bl foo, 
				   to save fprs??? */

	  fdata->frameless = 0;
	  /* Don't skip over the subroutine call if it is not within
	     the first three instructions of the prologue.  */
	  if ((pc - orig_pc) > 8)
	    break;

	  op = read_memory_integer (pc + 4, 4);

	  /* At this point, make sure this is not a trampoline
	     function (a function that simply calls another functions,
	     and nothing else).  If the next is not a nop, this branch
	     was part of the function prologue. */

	  if (op == 0x4def7b82 || op == 0)	/* crorc 15, 15, 15 */
	    break;		/* don't skip over 
				   this branch */
	  continue;

	  /* update stack pointer */
	}
      else if ((op & 0xffff0000) == 0x94210000 ||	/* stu r1,NUM(r1) */
	       (op & 0xffff0003) == 0xf8210001)		/* stdu r1,NUM(r1) */
	{
	  fdata->frameless = 0;
	  if ((op & 0xffff0003) == 0xf8210001)
	    op = (op >> 1) << 1;
	  fdata->offset = SIGNED_SHORT (op);
	  offset = fdata->offset;
	  continue;

	}
      else if (op == 0x7c21016e)
	{			/* stwux 1,1,0 */
	  fdata->frameless = 0;
	  offset = fdata->offset;
	  continue;

	  /* Load up minimal toc pointer */
	}
      else if ((op >> 22) == 0x20f
	       && !minimal_toc_loaded)
	{			/* l r31,... or l r30,... */
	  minimal_toc_loaded = 1;
	  continue;

	  /* move parameters from argument registers to local variable
             registers */
 	}
      else if ((op & 0xfc0007fe) == 0x7c000378 &&	/* mr(.)  Rx,Ry */
               (((op >> 21) & 31) >= 3) &&              /* R3 >= Ry >= R10 */
               (((op >> 21) & 31) <= 10) &&
               ((long) ((op >> 16) & 31) >= fdata->saved_gpr)) /* Rx: local var reg */
	{
	  continue;

	  /* store parameters in stack */
	}
      else if ((op & 0xfc1f0003) == 0xf8010000 ||	/* std rx,NUM(r1) */
	       (op & 0xfc1f0000) == 0xd8010000 ||	/* stfd Rx,NUM(r1) */
	       (op & 0xfc1f0000) == 0xfc010000)		/* frsp, fp?,NUM(r1) */
	{
	  continue;

	  /* store parameters in stack via frame pointer */
	}
      else if (framep &&
	       ((op & 0xfc1f0000) == 0x901f0000 ||	/* st rx,NUM(r1) */
		(op & 0xfc1f0000) == 0xd81f0000 ||	/* stfd Rx,NUM(r1) */
		(op & 0xfc1f0000) == 0xfc1f0000))
	{			/* frsp, fp?,NUM(r1) */
	  continue;

	  /* Set up frame pointer */
	}
      else if (op == 0x603f0000	/* oril r31, r1, 0x0 */
	       || op == 0x7c3f0b78)
	{			/* mr r31, r1 */
	  fdata->frameless = 0;
	  framep = 1;
	  fdata->alloca_reg = (tdep->ppc_gp0_regnum + 31);
	  continue;

	  /* Another way to set up the frame pointer.  */
	}
      else if ((op & 0xfc1fffff) == 0x38010000)
	{			/* addi rX, r1, 0x0 */
	  fdata->frameless = 0;
	  framep = 1;
	  fdata->alloca_reg = (tdep->ppc_gp0_regnum
			       + ((op & ~0x38010000) >> 21));
	  continue;
	}
      /* AltiVec related instructions.  */
      /* Store the vrsave register (spr 256) in another register for
	 later manipulation, or load a register into the vrsave
	 register.  2 instructions are used: mfvrsave and
	 mtvrsave.  They are shorthand notation for mfspr Rn, SPR256
	 and mtspr SPR256, Rn.  */
      /* mfspr Rn SPR256 == 011111 nnnnn 0000001000 01010100110
	 mtspr SPR256 Rn == 011111 nnnnn 0000001000 01110100110  */
      else if ((op & 0xfc1fffff) == 0x7c0042a6)    /* mfvrsave Rn */
	{
          vrsave_reg = GET_SRC_REG (op);
	  continue;
	}
      else if ((op & 0xfc1fffff) == 0x7c0043a6)     /* mtvrsave Rn */
        {
          continue;
        }
      /* Store the register where vrsave was saved to onto the stack:
         rS is the register where vrsave was stored in a previous
	 instruction.  */
      /* 100100 sssss 00001 dddddddd dddddddd */
      else if ((op & 0xfc1f0000) == 0x90010000)     /* stw rS, d(r1) */
        {
          if (vrsave_reg == GET_SRC_REG (op))
	    {
	      fdata->vrsave_offset = SIGNED_SHORT (op) + offset;
	      vrsave_reg = -1;
	    }
          continue;
        }
      /* Compute the new value of vrsave, by modifying the register
         where vrsave was saved to.  */
      else if (((op & 0xfc000000) == 0x64000000)    /* oris Ra, Rs, UIMM */
	       || ((op & 0xfc000000) == 0x60000000))/* ori Ra, Rs, UIMM */
	{
	  continue;
	}
      /* li r0, SIMM (short for addi r0, 0, SIMM).  This is the first
	 in a pair of insns to save the vector registers on the
	 stack.  */
      /* 001110 00000 00000 iiii iiii iiii iiii  */
      /* 001110 01110 00000 iiii iiii iiii iiii  */
      else if ((op & 0xffff0000) == 0x38000000         /* li r0, SIMM */
               || (op & 0xffff0000) == 0x39c00000)     /* li r14, SIMM */
	{
	  li_found_pc = pc;
	  vr_saved_offset = SIGNED_SHORT (op);
	}
      /* Store vector register S at (r31+r0) aligned to 16 bytes.  */      
      /* 011111 sssss 11111 00000 00111001110 */
      else if ((op & 0xfc1fffff) == 0x7c1f01ce)   /* stvx Vs, R31, R0 */
        {
	  if (pc == (li_found_pc + 4))
	    {
	      vr_reg = GET_SRC_REG (op);
	      /* If this is the first vector reg to be saved, or if
		 it has a lower number than others previously seen,
		 reupdate the frame info.  */
	      if (fdata->saved_vr == -1 || fdata->saved_vr > vr_reg)
		{
		  fdata->saved_vr = vr_reg;
		  fdata->vr_offset = vr_saved_offset + offset;
		}
	      vr_saved_offset = -1;
	      vr_reg = -1;
	      li_found_pc = 0;
	    }
	}
      /* End AltiVec related instructions.  */

      /* Start BookE related instructions.  */
      /* Store gen register S at (r31+uimm).
         Any register less than r13 is volatile, so we don't care.  */
      /* 000100 sssss 11111 iiiii 01100100001 */
      else if (arch_info->mach == bfd_mach_ppc_e500
	       && (op & 0xfc1f07ff) == 0x101f0321)    /* evstdd Rs,uimm(R31) */
	{
          if ((op & 0x03e00000) >= 0x01a00000)	/* Rs >= r13 */
	    {
              unsigned int imm;
	      ev_reg = GET_SRC_REG (op);
              imm = (op >> 11) & 0x1f;
	      ev_offset = imm * 8;
	      /* If this is the first vector reg to be saved, or if
		 it has a lower number than others previously seen,
		 reupdate the frame info.  */
	      if (fdata->saved_ev == -1 || fdata->saved_ev > ev_reg)
		{
		  fdata->saved_ev = ev_reg;
		  fdata->ev_offset = ev_offset + offset;
		}
	    }
          continue;
        }
      /* Store gen register rS at (r1+rB).  */
      /* 000100 sssss 00001 bbbbb 01100100000 */
      else if (arch_info->mach == bfd_mach_ppc_e500
	       && (op & 0xffe007ff) == 0x13e00320)     /* evstddx RS,R1,Rb */
	{
          if (pc == (li_found_pc + 4))
            {
              ev_reg = GET_SRC_REG (op);
	      /* If this is the first vector reg to be saved, or if
                 it has a lower number than others previously seen,
                 reupdate the frame info.  */
              /* We know the contents of rB from the previous instruction.  */
	      if (fdata->saved_ev == -1 || fdata->saved_ev > ev_reg)
		{
                  fdata->saved_ev = ev_reg;
                  fdata->ev_offset = vr_saved_offset + offset;
		}
	      vr_saved_offset = -1;
	      ev_reg = -1;
	      li_found_pc = 0;
            }
          continue;
        }
      /* Store gen register r31 at (rA+uimm).  */
      /* 000100 11111 aaaaa iiiii 01100100001 */
      else if (arch_info->mach == bfd_mach_ppc_e500
	       && (op & 0xffe007ff) == 0x13e00321)   /* evstdd R31,Ra,UIMM */
        {
          /* Wwe know that the source register is 31 already, but
             it can't hurt to compute it.  */
	  ev_reg = GET_SRC_REG (op);
          ev_offset = ((op >> 11) & 0x1f) * 8;
	  /* If this is the first vector reg to be saved, or if
	     it has a lower number than others previously seen,
	     reupdate the frame info.  */
	  if (fdata->saved_ev == -1 || fdata->saved_ev > ev_reg)
	    {
	      fdata->saved_ev = ev_reg;
	      fdata->ev_offset = ev_offset + offset;
	    }

	  continue;
      	}
      /* Store gen register S at (r31+r0).
         Store param on stack when offset from SP bigger than 4 bytes.  */
      /* 000100 sssss 11111 00000 01100100000 */
      else if (arch_info->mach == bfd_mach_ppc_e500
	       && (op & 0xfc1fffff) == 0x101f0320)     /* evstddx Rs,R31,R0 */
	{
          if (pc == (li_found_pc + 4))
            {
              if ((op & 0x03e00000) >= 0x01a00000)
		{
		  ev_reg = GET_SRC_REG (op);
		  /* If this is the first vector reg to be saved, or if
		     it has a lower number than others previously seen,
		     reupdate the frame info.  */
                  /* We know the contents of r0 from the previous
                     instruction.  */
		  if (fdata->saved_ev == -1 || fdata->saved_ev > ev_reg)
		    {
		      fdata->saved_ev = ev_reg;
		      fdata->ev_offset = vr_saved_offset + offset;
		    }
		  ev_reg = -1;
		}
	      vr_saved_offset = -1;
	      li_found_pc = 0;
	      continue;
            }
	}
      /* End BookE related instructions.  */

      else
	{
	  /* Not a recognized prologue instruction.
	     Handle optimizer code motions into the prologue by continuing
	     the search if we have no valid frame yet or if the return
	     address is not yet saved in the frame.  */
	  if (fdata->frameless == 0
	      && (lr_reg == -1 || fdata->nosavedpc == 0))
	    break;

	  if (op == 0x4e800020		/* blr */
	      || op == 0x4e800420)	/* bctr */
	    /* Do not scan past epilogue in frameless functions or
	       trampolines.  */
	    break;
	  if ((op & 0xf4000000) == 0x40000000) /* bxx */
	    /* Never skip branches.  */
	    break;

	  if (num_skip_non_prologue_insns++ > max_skip_non_prologue_insns)
	    /* Do not scan too many insns, scanning insns is expensive with
	       remote targets.  */
	    break;

	  /* Continue scanning.  */
	  prev_insn_was_prologue_insn = 0;
	  continue;
	}
    }

#if 0
/* I have problems with skipping over __main() that I need to address
 * sometime. Previously, I used to use misc_function_vector which
 * didn't work as well as I wanted to be.  -MGO */

  /* If the first thing after skipping a prolog is a branch to a function,
     this might be a call to an initializer in main(), introduced by gcc2.
     We'd like to skip over it as well.  Fortunately, xlc does some extra
     work before calling a function right after a prologue, thus we can
     single out such gcc2 behaviour.  */


  if ((op & 0xfc000001) == 0x48000001)
    {				/* bl foo, an initializer function? */
      op = read_memory_integer (pc + 4, 4);

      if (op == 0x4def7b82)
	{			/* cror 0xf, 0xf, 0xf (nop) */

	  /* Check and see if we are in main.  If so, skip over this
	     initializer function as well.  */

	  tmp = find_pc_misc_function (pc);
	  if (tmp >= 0 && STREQ (misc_function_vector[tmp].name, main_name ()))
	    return pc + 8;
	}
    }
#endif /* 0 */

  fdata->offset = -fdata->offset;
  return last_prologue_pc;
}


/*************************************************************************
  Support for creating pushing a dummy frame into the stack, and popping
  frames, etc. 
*************************************************************************/


/* Pop the innermost frame, go back to the caller.  */

static void
rs6000_pop_frame (void)
{
  CORE_ADDR pc, lr, sp, prev_sp, addr;	/* %pc, %lr, %sp */
  struct rs6000_framedata fdata;
  struct frame_info *frame = get_current_frame ();
  int ii, wordsize;

  pc = read_pc ();
  sp = get_frame_base (frame);

  if (DEPRECATED_PC_IN_CALL_DUMMY (get_frame_pc (frame),
				   get_frame_base (frame),
				   get_frame_base (frame)))
    {
      generic_pop_dummy_frame ();
      flush_cached_frames ();
      return;
    }

  /* Make sure that all registers are valid.  */
  deprecated_read_register_bytes (0, NULL, REGISTER_BYTES);

  /* Figure out previous %pc value.  If the function is frameless, it is 
     still in the link register, otherwise walk the frames and retrieve the
     saved %pc value in the previous frame.  */

  addr = get_pc_function_start (get_frame_pc (frame));
  (void) skip_prologue (addr, get_frame_pc (frame), &fdata);

  wordsize = gdbarch_tdep (current_gdbarch)->wordsize;
  if (fdata.frameless)
    prev_sp = sp;
  else
    prev_sp = read_memory_addr (sp, wordsize);
  if (fdata.lr_offset == 0)
     lr = read_register (gdbarch_tdep (current_gdbarch)->ppc_lr_regnum);
  else
    lr = read_memory_addr (prev_sp + fdata.lr_offset, wordsize);

  /* reset %pc value. */
  write_register (PC_REGNUM, lr);

  /* reset register values if any was saved earlier.  */

  if (fdata.saved_gpr != -1)
    {
      addr = prev_sp + fdata.gpr_offset;
      for (ii = fdata.saved_gpr; ii <= 31; ++ii)
	{
	  read_memory (addr, &deprecated_registers[REGISTER_BYTE (ii)],
		       wordsize);
	  addr += wordsize;
	}
    }

  if (fdata.saved_fpr != -1)
    {
      addr = prev_sp + fdata.fpr_offset;
      for (ii = fdata.saved_fpr; ii <= 31; ++ii)
	{
	  read_memory (addr, &deprecated_registers[REGISTER_BYTE (ii + FP0_REGNUM)], 8);
	  addr += 8;
	}
    }

  write_register (SP_REGNUM, prev_sp);
  target_store_registers (-1);
  flush_cached_frames ();
}

/* Fixup the call sequence of a dummy function, with the real function
   address.  Its arguments will be passed by gdb.  */

static void
rs6000_fix_call_dummy (char *dummyname, CORE_ADDR pc, CORE_ADDR fun,
		       int nargs, struct value **args, struct type *type,
		       int gcc_p)
{
  int ii;
  CORE_ADDR target_addr;

  if (rs6000_find_toc_address_hook != NULL)
    {
      CORE_ADDR tocvalue = (*rs6000_find_toc_address_hook) (fun);
      write_register (gdbarch_tdep (current_gdbarch)->ppc_toc_regnum,
		      tocvalue);
    }
}

/* All the ABI's require 16 byte alignment.  */
static CORE_ADDR
rs6000_frame_align (struct gdbarch *gdbarch, CORE_ADDR addr)
{
  return (addr & -16);
}

/* Pass the arguments in either registers, or in the stack. In RS/6000,
   the first eight words of the argument list (that might be less than
   eight parameters if some parameters occupy more than one word) are
   passed in r3..r10 registers.  float and double parameters are
   passed in fpr's, in addition to that.  Rest of the parameters if any
   are passed in user stack.  There might be cases in which half of the
   parameter is copied into registers, the other half is pushed into
   stack.

   Stack must be aligned on 64-bit boundaries when synthesizing
   function calls.

   If the function is returning a structure, then the return address is passed
   in r3, then the first 7 words of the parameters can be passed in registers,
   starting from r4.  */

static CORE_ADDR
rs6000_push_arguments (int nargs, struct value **args, CORE_ADDR sp,
		       int struct_return, CORE_ADDR struct_addr)
{
  int ii;
  int len = 0;
  int argno;			/* current argument number */
  int argbytes;			/* current argument byte */
  char tmp_buffer[50];
  int f_argno = 0;		/* current floating point argno */
  int wordsize = gdbarch_tdep (current_gdbarch)->wordsize;

  struct value *arg = 0;
  struct type *type;

  CORE_ADDR saved_sp;

  /* The first eight words of ther arguments are passed in registers.
     Copy them appropriately.

     If the function is returning a `struct', then the first word (which 
     will be passed in r3) is used for struct return address.  In that
     case we should advance one word and start from r4 register to copy 
     parameters.  */

  ii = struct_return ? 1 : 0;

/* 
   effectively indirect call... gcc does...

   return_val example( float, int);

   eabi: 
   float in fp0, int in r3
   offset of stack on overflow 8/16
   for varargs, must go by type.
   power open:
   float in r3&r4, int in r5
   offset of stack on overflow different 
   both: 
   return in r3 or f0.  If no float, must study how gcc emulates floats;
   pay attention to arg promotion.  
   User may have to cast\args to handle promotion correctly 
   since gdb won't know if prototype supplied or not.
 */

  for (argno = 0, argbytes = 0; argno < nargs && ii < 8; ++ii)
    {
      int reg_size = REGISTER_RAW_SIZE (ii + 3);

      arg = args[argno];
      type = check_typedef (VALUE_TYPE (arg));
      len = TYPE_LENGTH (type);

      if (TYPE_CODE (type) == TYPE_CODE_FLT)
	{

	  /* Floating point arguments are passed in fpr's, as well as gpr's.
	     There are 13 fpr's reserved for passing parameters. At this point
	     there is no way we would run out of them.  */

	  if (len > 8)
	    printf_unfiltered (
				"Fatal Error: a floating point parameter #%d with a size > 8 is found!\n", argno);

	  memcpy (&deprecated_registers[REGISTER_BYTE (FP0_REGNUM + 1 + f_argno)],
		  VALUE_CONTENTS (arg),
		  len);
	  ++f_argno;
	}

      if (len > reg_size)
	{

	  /* Argument takes more than one register.  */
	  while (argbytes < len)
	    {
	      memset (&deprecated_registers[REGISTER_BYTE (ii + 3)], 0,
		      reg_size);
	      memcpy (&deprecated_registers[REGISTER_BYTE (ii + 3)],
		      ((char *) VALUE_CONTENTS (arg)) + argbytes,
		      (len - argbytes) > reg_size
		        ? reg_size : len - argbytes);
	      ++ii, argbytes += reg_size;

	      if (ii >= 8)
		goto ran_out_of_registers_for_arguments;
	    }
	  argbytes = 0;
	  --ii;
	}
      else
	{
	  /* Argument can fit in one register.  No problem.  */
	  int adj = TARGET_BYTE_ORDER == BFD_ENDIAN_BIG ? reg_size - len : 0;
	  memset (&deprecated_registers[REGISTER_BYTE (ii + 3)], 0, reg_size);
	  memcpy ((char *)&deprecated_registers[REGISTER_BYTE (ii + 3)] + adj, 
	          VALUE_CONTENTS (arg), len);
	}
      ++argno;
    }

ran_out_of_registers_for_arguments:

  saved_sp = read_sp ();

  /* Location for 8 parameters are always reserved.  */
  sp -= wordsize * 8;

  /* Another six words for back chain, TOC register, link register, etc.  */
  sp -= wordsize * 6;

  /* Stack pointer must be quadword aligned.  */
  sp &= -16;

  /* If there are more arguments, allocate space for them in 
     the stack, then push them starting from the ninth one.  */

  if ((argno < nargs) || argbytes)
    {
      int space = 0, jj;

      if (argbytes)
	{
	  space += ((len - argbytes + 3) & -4);
	  jj = argno + 1;
	}
      else
	jj = argno;

      for (; jj < nargs; ++jj)
	{
	  struct value *val = args[jj];
	  space += ((TYPE_LENGTH (VALUE_TYPE (val))) + 3) & -4;
	}

      /* Add location required for the rest of the parameters.  */
      space = (space + 15) & -16;
      sp -= space;

      /* This is another instance we need to be concerned about
         securing our stack space. If we write anything underneath %sp
         (r1), we might conflict with the kernel who thinks he is free
         to use this area. So, update %sp first before doing anything
         else.  */

      write_register (SP_REGNUM, sp);

      /* If the last argument copied into the registers didn't fit there 
         completely, push the rest of it into stack.  */

      if (argbytes)
	{
	  write_memory (sp + 24 + (ii * 4),
			((char *) VALUE_CONTENTS (arg)) + argbytes,
			len - argbytes);
	  ++argno;
	  ii += ((len - argbytes + 3) & -4) / 4;
	}

      /* Push the rest of the arguments into stack.  */
      for (; argno < nargs; ++argno)
	{

	  arg = args[argno];
	  type = check_typedef (VALUE_TYPE (arg));
	  len = TYPE_LENGTH (type);


	  /* Float types should be passed in fpr's, as well as in the
             stack.  */
	  if (TYPE_CODE (type) == TYPE_CODE_FLT && f_argno < 13)
	    {

	      if (len > 8)
		printf_unfiltered (
				    "Fatal Error: a floating point parameter #%d with a size > 8 is found!\n", argno);

	      memcpy (&deprecated_registers[REGISTER_BYTE (FP0_REGNUM + 1 + f_argno)],
		      VALUE_CONTENTS (arg),
		      len);
	      ++f_argno;
	    }

	  write_memory (sp + 24 + (ii * 4), (char *) VALUE_CONTENTS (arg), len);
	  ii += ((len + 3) & -4) / 4;
	}
    }
  else
    /* Secure stack areas first, before doing anything else.  */
    write_register (SP_REGNUM, sp);

  /* set back chain properly */
  store_address (tmp_buffer, 4, saved_sp);
  write_memory (sp, tmp_buffer, 4);

  target_store_registers (-1);
  return sp;
}

/* Function: ppc_push_return_address (pc, sp)
   Set up the return address for the inferior function call.  */

static CORE_ADDR
ppc_push_return_address (CORE_ADDR pc, CORE_ADDR sp)
{
  write_register (gdbarch_tdep (current_gdbarch)->ppc_lr_regnum,
		  CALL_DUMMY_ADDRESS ());
  return sp;
}

/* Extract a function return value of type TYPE from raw register array
   REGBUF, and copy that return value into VALBUF in virtual format.  */
static void
e500_extract_return_value (struct type *valtype, struct regcache *regbuf, void *valbuf)
{
  int offset = 0;
  int vallen = TYPE_LENGTH (valtype);
  struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);

  if (TYPE_CODE (valtype) == TYPE_CODE_ARRAY
      && vallen == 8
      && TYPE_VECTOR (valtype))
    {
      regcache_raw_read (regbuf, tdep->ppc_ev0_regnum + 3, valbuf);
    }
  else
    {
      /* Return value is copied starting from r3.  Note that r3 for us
         is a pseudo register.  */
      int offset = 0;
      int return_regnum = tdep->ppc_gp0_regnum + 3;
      int reg_size = REGISTER_RAW_SIZE (return_regnum);
      int reg_part_size;
      char *val_buffer;
      int copied = 0;
      int i = 0;

      /* Compute where we will start storing the value from.  */ 
      if (TARGET_BYTE_ORDER == BFD_ENDIAN_BIG)
        {
	  if (vallen <= reg_size)
	    offset = reg_size - vallen;
	  else
	    offset = reg_size + (reg_size - vallen);
        }

      /* How big does the local buffer need to be?  */
      if (vallen <= reg_size)
	val_buffer = alloca (reg_size);
      else
	val_buffer = alloca (vallen);

      /* Read all we need into our private buffer.  We copy it in
         chunks that are as long as one register, never shorter, even
         if the value is smaller than the register.  */
      while (copied < vallen)
        {
          reg_part_size = REGISTER_RAW_SIZE (return_regnum + i);
	  /* It is a pseudo/cooked register.  */
          regcache_cooked_read (regbuf, return_regnum + i,
				val_buffer + copied);
          copied += reg_part_size;
          i++;
        }
      /* Put the stuff in the return buffer.  */
      memcpy (valbuf, val_buffer + offset, vallen);
    }
}

static void
rs6000_extract_return_value (struct type *valtype, char *regbuf, char *valbuf)
{
  int offset = 0;
  struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);

  if (TYPE_CODE (valtype) == TYPE_CODE_FLT)
    {

      double dd;
      float ff;
      /* floats and doubles are returned in fpr1. fpr's have a size of 8 bytes.
         We need to truncate the return value into float size (4 byte) if
         necessary.  */

      if (TYPE_LENGTH (valtype) > 4)	/* this is a double */
	memcpy (valbuf,
		&regbuf[REGISTER_BYTE (FP0_REGNUM + 1)],
		TYPE_LENGTH (valtype));
      else
	{			/* float */
	  memcpy (&dd, &regbuf[REGISTER_BYTE (FP0_REGNUM + 1)], 8);
	  ff = (float) dd;
	  memcpy (valbuf, &ff, sizeof (float));
	}
    }
  else if (TYPE_CODE (valtype) == TYPE_CODE_ARRAY
           && TYPE_LENGTH (valtype) == 16
           && TYPE_VECTOR (valtype))
    {
      memcpy (valbuf, regbuf + REGISTER_BYTE (tdep->ppc_vr0_regnum + 2),
	      TYPE_LENGTH (valtype));
    }
  else
    {
      /* return value is copied starting from r3. */
      if (TARGET_BYTE_ORDER == BFD_ENDIAN_BIG
	  && TYPE_LENGTH (valtype) < REGISTER_RAW_SIZE (3))
	offset = REGISTER_RAW_SIZE (3) - TYPE_LENGTH (valtype);

      memcpy (valbuf,
	      regbuf + REGISTER_BYTE (3) + offset,
	      TYPE_LENGTH (valtype));
    }
}

/* Return whether handle_inferior_event() should proceed through code
   starting at PC in function NAME when stepping.

   The AIX -bbigtoc linker option generates functions @FIX0, @FIX1, etc. to
   handle memory references that are too distant to fit in instructions
   generated by the compiler.  For example, if 'foo' in the following
   instruction:

     lwz r9,foo(r2)

   is greater than 32767, the linker might replace the lwz with a branch to
   somewhere in @FIX1 that does the load in 2 instructions and then branches
   back to where execution should continue.

   GDB should silently step over @FIX code, just like AIX dbx does.
   Unfortunately, the linker uses the "b" instruction for the branches,
   meaning that the link register doesn't get set.  Therefore, GDB's usual
   step_over_function() mechanism won't work.

   Instead, use the IN_SOLIB_RETURN_TRAMPOLINE and SKIP_TRAMPOLINE_CODE hooks
   in handle_inferior_event() to skip past @FIX code.  */

int
rs6000_in_solib_return_trampoline (CORE_ADDR pc, char *name)
{
  return name && !strncmp (name, "@FIX", 4);
}

/* Skip code that the user doesn't want to see when stepping:

   1. Indirect function calls use a piece of trampoline code to do context
   switching, i.e. to set the new TOC table.  Skip such code if we are on
   its first instruction (as when we have single-stepped to here).

   2. Skip shared library trampoline code (which is different from
   indirect function call trampolines).

   3. Skip bigtoc fixup code.

   Result is desired PC to step until, or NULL if we are not in
   code that should be skipped.  */

CORE_ADDR
rs6000_skip_trampoline_code (CORE_ADDR pc)
{
  register unsigned int ii, op;
  int rel;
  CORE_ADDR solib_target_pc;
  struct minimal_symbol *msymbol;

  static unsigned trampoline_code[] =
  {
    0x800b0000,			/*     l   r0,0x0(r11)  */
    0x90410014,			/*    st   r2,0x14(r1)  */
    0x7c0903a6,			/* mtctr   r0           */
    0x804b0004,			/*     l   r2,0x4(r11)  */
    0x816b0008,			/*     l  r11,0x8(r11)  */
    0x4e800420,			/*  bctr                */
    0x4e800020,			/*    br                */
    0
  };

  /* Check for bigtoc fixup code.  */
  msymbol = lookup_minimal_symbol_by_pc (pc);
  if (msymbol && rs6000_in_solib_return_trampoline (pc, DEPRECATED_SYMBOL_NAME (msymbol)))
    {
      /* Double-check that the third instruction from PC is relative "b".  */
      op = read_memory_integer (pc + 8, 4);
      if ((op & 0xfc000003) == 0x48000000)
	{
	  /* Extract bits 6-29 as a signed 24-bit relative word address and
	     add it to the containing PC.  */
	  rel = ((int)(op << 6) >> 6);
	  return pc + 8 + rel;
	}
    }

  /* If pc is in a shared library trampoline, return its target.  */
  solib_target_pc = find_solib_trampoline_target (pc);
  if (solib_target_pc)
    return solib_target_pc;

  for (ii = 0; trampoline_code[ii]; ++ii)
    {
      op = read_memory_integer (pc + (ii * 4), 4);
      if (op != trampoline_code[ii])
	return 0;
    }
  ii = read_register (11);	/* r11 holds destination addr   */
  pc = read_memory_addr (ii, gdbarch_tdep (current_gdbarch)->wordsize); /* (r11) value */
  return pc;
}

/* Determines whether the function FI has a frame on the stack or not.  */

int
rs6000_frameless_function_invocation (struct frame_info *fi)
{
  CORE_ADDR func_start;
  struct rs6000_framedata fdata;

  /* Don't even think about framelessness except on the innermost frame
     or if the function was interrupted by a signal.  */
  if (get_next_frame (fi) != NULL
      && !(get_frame_type (get_next_frame (fi)) == SIGTRAMP_FRAME))
    return 0;

  func_start = get_pc_function_start (get_frame_pc (fi));

  /* If we failed to find the start of the function, it is a mistake
     to inspect the instructions.  */

  if (!func_start)
    {
      /* A frame with a zero PC is usually created by dereferencing a NULL
         function pointer, normally causing an immediate core dump of the
         inferior.  Mark function as frameless, as the inferior has no chance
         of setting up a stack frame.  */
      if (get_frame_pc (fi) == 0)
	return 1;
      else
	return 0;
    }

  (void) skip_prologue (func_start, get_frame_pc (fi), &fdata);
  return fdata.frameless;
}

/* Return the PC saved in a frame.  */

CORE_ADDR
rs6000_frame_saved_pc (struct frame_info *fi)
{
  CORE_ADDR func_start;
  struct rs6000_framedata fdata;
  struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
  int wordsize = tdep->wordsize;

  if ((get_frame_type (fi) == SIGTRAMP_FRAME))
    return read_memory_addr (get_frame_base (fi) + SIG_FRAME_PC_OFFSET,
			     wordsize);

  if (DEPRECATED_PC_IN_CALL_DUMMY (get_frame_pc (fi),
				   get_frame_base (fi),
				   get_frame_base (fi)))
    return deprecated_read_register_dummy (get_frame_pc (fi),
					   get_frame_base (fi), PC_REGNUM);

  func_start = get_pc_function_start (get_frame_pc (fi));

  /* If we failed to find the start of the function, it is a mistake
     to inspect the instructions.  */
  if (!func_start)
    return 0;

  (void) skip_prologue (func_start, get_frame_pc (fi), &fdata);

  if (fdata.lr_offset == 0 && get_next_frame (fi) != NULL)
    {
      if ((get_frame_type (get_next_frame (fi)) == SIGTRAMP_FRAME))
	return read_memory_addr ((get_frame_base (get_next_frame (fi))
				  + SIG_FRAME_LR_OFFSET),
				 wordsize);
      else if (DEPRECATED_PC_IN_CALL_DUMMY (get_frame_pc (get_next_frame (fi)), 0, 0))
	/* The link register wasn't saved by this frame and the next
           (inner, newer) frame is a dummy.  Get the link register
           value by unwinding it from that [dummy] frame.  */
	{
	  ULONGEST lr;
	  frame_unwind_unsigned_register (get_next_frame (fi),
					  tdep->ppc_lr_regnum, &lr);
	  return lr;
	}
      else
	return read_memory_addr (FRAME_CHAIN (fi) + tdep->lr_frame_offset,
				 wordsize);
    }

  if (fdata.lr_offset == 0)
    return read_register (gdbarch_tdep (current_gdbarch)->ppc_lr_regnum);

  return read_memory_addr (FRAME_CHAIN (fi) + fdata.lr_offset, wordsize);
}

/* If saved registers of frame FI are not known yet, read and cache them.
   &FDATAP contains rs6000_framedata; TDATAP can be NULL,
   in which case the framedata are read.  */

static void
frame_get_saved_regs (struct frame_info *fi, struct rs6000_framedata *fdatap)
{
  CORE_ADDR frame_addr;
  struct rs6000_framedata work_fdata;
  struct gdbarch_tdep * tdep = gdbarch_tdep (current_gdbarch);
  int wordsize = tdep->wordsize;

  if (get_frame_saved_regs (fi))
    return;

  if (fdatap == NULL)
    {
      fdatap = &work_fdata;
      (void) skip_prologue (get_pc_function_start (get_frame_pc (fi)),
			    get_frame_pc (fi), fdatap);
    }

  frame_saved_regs_zalloc (fi);

  /* If there were any saved registers, figure out parent's stack
     pointer.  */
  /* The following is true only if the frame doesn't have a call to
     alloca(), FIXME.  */

  if (fdatap->saved_fpr == 0
      && fdatap->saved_gpr == 0
      && fdatap->saved_vr == 0
      && fdatap->saved_ev == 0
      && fdatap->lr_offset == 0
      && fdatap->cr_offset == 0
      && fdatap->vr_offset == 0
      && fdatap->ev_offset == 0)
    frame_addr = 0;
  else
    /* NOTE: cagney/2002-04-14: The ->frame points to the inner-most
       address of the current frame.  Things might be easier if the
       ->frame pointed to the outer-most address of the frame.  In the
       mean time, the address of the prev frame is used as the base
       address of this frame.  */
    frame_addr = FRAME_CHAIN (fi);

  /* if != -1, fdatap->saved_fpr is the smallest number of saved_fpr.
     All fpr's from saved_fpr to fp31 are saved.  */

  if (fdatap->saved_fpr >= 0)
    {
      int i;
      CORE_ADDR fpr_addr = frame_addr + fdatap->fpr_offset;
      for (i = fdatap->saved_fpr; i < 32; i++)
	{
	  get_frame_saved_regs (fi)[FP0_REGNUM + i] = fpr_addr;
	  fpr_addr += 8;
	}
    }

  /* if != -1, fdatap->saved_gpr is the smallest number of saved_gpr.
     All gpr's from saved_gpr to gpr31 are saved.  */

  if (fdatap->saved_gpr >= 0)
    {
      int i;
      CORE_ADDR gpr_addr = frame_addr + fdatap->gpr_offset;
      for (i = fdatap->saved_gpr; i < 32; i++)
	{
	  get_frame_saved_regs (fi)[i] = gpr_addr;
	  gpr_addr += wordsize;
	}
    }

  /* if != -1, fdatap->saved_vr is the smallest number of saved_vr.
     All vr's from saved_vr to vr31 are saved.  */
  if (tdep->ppc_vr0_regnum != -1 && tdep->ppc_vrsave_regnum != -1)
    {
      if (fdatap->saved_vr >= 0)
	{
	  int i;
	  CORE_ADDR vr_addr = frame_addr + fdatap->vr_offset;
	  for (i = fdatap->saved_vr; i < 32; i++)
	    {
	      get_frame_saved_regs (fi)[tdep->ppc_vr0_regnum + i] = vr_addr;
	      vr_addr += REGISTER_RAW_SIZE (tdep->ppc_vr0_regnum);
	    }
	}
    }

  /* if != -1, fdatap->saved_ev is the smallest number of saved_ev.
	All vr's from saved_ev to ev31 are saved. ?????	*/
  if (tdep->ppc_ev0_regnum != -1 && tdep->ppc_ev31_regnum != -1)
    {
      if (fdatap->saved_ev >= 0)
	{
	  int i;
	  CORE_ADDR ev_addr = frame_addr + fdatap->ev_offset;
	  for (i = fdatap->saved_ev; i < 32; i++)
	    {
	      get_frame_saved_regs (fi)[tdep->ppc_ev0_regnum + i] = ev_addr;
              get_frame_saved_regs (fi)[tdep->ppc_gp0_regnum + i] = ev_addr + 4;
	      ev_addr += REGISTER_RAW_SIZE (tdep->ppc_ev0_regnum);
            }
	}
    }

  /* If != 0, fdatap->cr_offset is the offset from the frame that holds
     the CR.  */
  if (fdatap->cr_offset != 0)
    get_frame_saved_regs (fi)[tdep->ppc_cr_regnum] = frame_addr + fdatap->cr_offset;

  /* If != 0, fdatap->lr_offset is the offset from the frame that holds
     the LR.  */
  if (fdatap->lr_offset != 0)
    get_frame_saved_regs (fi)[tdep->ppc_lr_regnum] = frame_addr + fdatap->lr_offset;

  /* If != 0, fdatap->vrsave_offset is the offset from the frame that holds
     the VRSAVE.  */
  if (fdatap->vrsave_offset != 0)
    get_frame_saved_regs (fi)[tdep->ppc_vrsave_regnum] = frame_addr + fdatap->vrsave_offset;
}

/* Return the address of a frame. This is the inital %sp value when the frame
   was first allocated.  For functions calling alloca(), it might be saved in
   an alloca register.  */

static CORE_ADDR
frame_initial_stack_address (struct frame_info *fi)
{
  CORE_ADDR tmpaddr;
  struct rs6000_framedata fdata;
  struct frame_info *callee_fi;

  /* If the initial stack pointer (frame address) of this frame is known,
     just return it.  */

  if (get_frame_extra_info (fi)->initial_sp)
    return get_frame_extra_info (fi)->initial_sp;

  /* Find out if this function is using an alloca register.  */

  (void) skip_prologue (get_pc_function_start (get_frame_pc (fi)),
			get_frame_pc (fi), &fdata);

  /* If saved registers of this frame are not known yet, read and
     cache them.  */

  if (!get_frame_saved_regs (fi))
    frame_get_saved_regs (fi, &fdata);

  /* If no alloca register used, then fi->frame is the value of the %sp for
     this frame, and it is good enough.  */

  if (fdata.alloca_reg < 0)
    {
      get_frame_extra_info (fi)->initial_sp = get_frame_base (fi);
      return get_frame_extra_info (fi)->initial_sp;
    }

  /* There is an alloca register, use its value, in the current frame,
     as the initial stack pointer.  */
  {
    char *tmpbuf = alloca (MAX_REGISTER_RAW_SIZE);
    if (frame_register_read (fi, fdata.alloca_reg, tmpbuf))
      {
	get_frame_extra_info (fi)->initial_sp
	  = extract_unsigned_integer (tmpbuf,
				      REGISTER_RAW_SIZE (fdata.alloca_reg));
      }
    else
      /* NOTE: cagney/2002-04-17: At present the only time
         frame_register_read will fail is when the register isn't
         available.  If that does happen, use the frame.  */
      get_frame_extra_info (fi)->initial_sp = get_frame_base (fi);
  }
  return get_frame_extra_info (fi)->initial_sp;
}

/* Describe the pointer in each stack frame to the previous stack frame
   (its caller).  */

/* FRAME_CHAIN takes a frame's nominal address
   and produces the frame's chain-pointer.  */

/* In the case of the RS/6000, the frame's nominal address
   is the address of a 4-byte word containing the calling frame's address.  */

CORE_ADDR
rs6000_frame_chain (struct frame_info *thisframe)
{
  CORE_ADDR fp, fpp, lr;
  int wordsize = gdbarch_tdep (current_gdbarch)->wordsize;

  if (DEPRECATED_PC_IN_CALL_DUMMY (get_frame_pc (thisframe),
				   get_frame_base (thisframe),
				   get_frame_base (thisframe)))
    /* A dummy frame always correctly chains back to the previous
       frame.  */
    return read_memory_addr (get_frame_base (thisframe), wordsize);

  if (inside_entry_file (get_frame_pc (thisframe))
      || get_frame_pc (thisframe) == entry_point_address ())
    return 0;

  if ((get_frame_type (thisframe) == SIGTRAMP_FRAME))
    fp = read_memory_addr (get_frame_base (thisframe) + SIG_FRAME_FP_OFFSET,
			   wordsize);
  else if (get_next_frame (thisframe) != NULL
	   && (get_frame_type (get_next_frame (thisframe)) == SIGTRAMP_FRAME)
	   && FRAMELESS_FUNCTION_INVOCATION (thisframe))
    /* A frameless function interrupted by a signal did not change the
       frame pointer.  */
    fp = get_frame_base (thisframe);
  else
    fp = read_memory_addr (get_frame_base (thisframe), wordsize);
  return fp;
}

/* Return the size of register REG when words are WORDSIZE bytes long.  If REG
   isn't available with that word size, return 0.  */

static int
regsize (const struct reg *reg, int wordsize)
{
  return wordsize == 8 ? reg->sz64 : reg->sz32;
}

/* Return the name of register number N, or null if no such register exists
   in the current architecture.  */

static const char *
rs6000_register_name (int n)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
  const struct reg *reg = tdep->regs + n;

  if (!regsize (reg, tdep->wordsize))
    return NULL;
  return reg->name;
}

/* Index within `registers' of the first byte of the space for
   register N.  */

static int
rs6000_register_byte (int n)
{
  return gdbarch_tdep (current_gdbarch)->regoff[n];
}

/* Return the number of bytes of storage in the actual machine representation
   for register N if that register is available, else return 0.  */

static int
rs6000_register_raw_size (int n)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
  const struct reg *reg = tdep->regs + n;
  return regsize (reg, tdep->wordsize);
}

/* Return the GDB type object for the "standard" data type
   of data in register N.  */

static struct type *
rs6000_register_virtual_type (int n)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
  const struct reg *reg = tdep->regs + n;

  if (reg->fpr)
    return builtin_type_double;
  else
    {
      int size = regsize (reg, tdep->wordsize);
      switch (size)
	{
	case 8:
	  if (tdep->ppc_ev0_regnum <= n && n <= tdep->ppc_ev31_regnum)
	    return builtin_type_vec64;
	  else
	    return builtin_type_int64;
	  break;
	case 16:
	  return builtin_type_vec128;
	  break;
	default:
	  return builtin_type_int32;
	  break;
	}
    }
}

/* Return whether register N requires conversion when moving from raw format
   to virtual format.

   The register format for RS/6000 floating point registers is always
   double, we need a conversion if the memory format is float.  */

static int
rs6000_register_convertible (int n)
{
  const struct reg *reg = gdbarch_tdep (current_gdbarch)->regs + n;
  return reg->fpr;
}

/* Convert data from raw format for register N in buffer FROM
   to virtual format with type TYPE in buffer TO.  */

static void
rs6000_register_convert_to_virtual (int n, struct type *type,
				    char *from, char *to)
{
  if (TYPE_LENGTH (type) != REGISTER_RAW_SIZE (n))
    {
      double val = extract_floating (from, REGISTER_RAW_SIZE (n));
      store_floating (to, TYPE_LENGTH (type), val);
    }
  else
    memcpy (to, from, REGISTER_RAW_SIZE (n));
}

/* Convert data from virtual format with type TYPE in buffer FROM
   to raw format for register N in buffer TO.  */

static void
rs6000_register_convert_to_raw (struct type *type, int n,
				char *from, char *to)
{
  if (TYPE_LENGTH (type) != REGISTER_RAW_SIZE (n))
    {
      double val = extract_floating (from, TYPE_LENGTH (type));
      store_floating (to, REGISTER_RAW_SIZE (n), val);
    }
  else
    memcpy (to, from, REGISTER_RAW_SIZE (n));
}

static void
e500_pseudo_register_read (struct gdbarch *gdbarch, struct regcache *regcache,
			   int reg_nr, void *buffer)
{
  int base_regnum;
  int offset = 0;
  char *temp_buffer = (char*) alloca (MAX_REGISTER_RAW_SIZE);
  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); 

  if (reg_nr >= tdep->ppc_gp0_regnum 
      && reg_nr <= tdep->ppc_gplast_regnum)
    {
      base_regnum = reg_nr - tdep->ppc_gp0_regnum + tdep->ppc_ev0_regnum;

      /* Build the value in the provided buffer.  */ 
      /* Read the raw register of which this one is the lower portion.  */
      regcache_raw_read (regcache, base_regnum, temp_buffer);
      if (TARGET_BYTE_ORDER == BFD_ENDIAN_BIG)
	offset = 4;
      memcpy ((char *) buffer, temp_buffer + offset, 4);
    }
}

static void
e500_pseudo_register_write (struct gdbarch *gdbarch, struct regcache *regcache,
			    int reg_nr, const void *buffer)
{
  int base_regnum;
  int offset = 0;
  char *temp_buffer = (char*) alloca (MAX_REGISTER_RAW_SIZE);
  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); 

  if (reg_nr >= tdep->ppc_gp0_regnum 
      && reg_nr <= tdep->ppc_gplast_regnum)
    {
      base_regnum = reg_nr - tdep->ppc_gp0_regnum + tdep->ppc_ev0_regnum;
      /* reg_nr is 32 bit here, and base_regnum is 64 bits.  */
      if (TARGET_BYTE_ORDER == BFD_ENDIAN_BIG)
	offset = 4;

      /* Let's read the value of the base register into a temporary
	 buffer, so that overwriting the last four bytes with the new
	 value of the pseudo will leave the upper 4 bytes unchanged.  */
      regcache_raw_read (regcache, base_regnum, temp_buffer);

      /* Write as an 8 byte quantity.  */
      memcpy (temp_buffer + offset, (char *) buffer, 4);
      regcache_raw_write (regcache, base_regnum, temp_buffer);
    }
}

/* Convert a dwarf2 register number to a gdb REGNUM.  */
static int
e500_dwarf2_reg_to_regnum (int num)
{
  int regnum;
  if (0 <= num && num <= 31)
    return num + gdbarch_tdep (current_gdbarch)->ppc_gp0_regnum;
  else 
    return num;
}

/* Convert a dbx stab register number (from `r' declaration) to a gdb
   REGNUM.  */
static int
rs6000_stab_reg_to_regnum (int num)
{
  int regnum;
  switch (num)
    {
    case 64: 
      regnum = gdbarch_tdep (current_gdbarch)->ppc_mq_regnum;
      break;
    case 65: 
      regnum = gdbarch_tdep (current_gdbarch)->ppc_lr_regnum;
      break;
    case 66: 
      regnum = gdbarch_tdep (current_gdbarch)->ppc_ctr_regnum;
      break;
    case 76: 
      regnum = gdbarch_tdep (current_gdbarch)->ppc_xer_regnum;
      break;
    default: 
      regnum = num;
      break;
    }
  return regnum;
}

/* Store the address of the place in which to copy the structure the
   subroutine will return.  */

static void
rs6000_store_struct_return (CORE_ADDR addr, CORE_ADDR sp)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
  write_register (tdep->ppc_gp0_regnum + 3, addr);
}

/* Write into appropriate registers a function return value
   of type TYPE, given in virtual format.  */
static void
e500_store_return_value (struct type *type, char *valbuf)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);

  /* Everything is returned in GPR3 and up.  */
  int copied = 0;
  int i = 0;
  int len = TYPE_LENGTH (type);
  while (copied < len)
    {
      int regnum = gdbarch_tdep (current_gdbarch)->ppc_gp0_regnum + 3 + i;
      int reg_size = REGISTER_RAW_SIZE (regnum);
      char *reg_val_buf = alloca (reg_size);

      memcpy (reg_val_buf, valbuf + copied, reg_size);
      copied += reg_size;
      deprecated_write_register_gen (regnum, reg_val_buf);
      i++;
    }
}

static void
rs6000_store_return_value (struct type *type, char *valbuf)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);

  if (TYPE_CODE (type) == TYPE_CODE_FLT)

    /* Floating point values are returned starting from FPR1 and up.
       Say a double_double_double type could be returned in
       FPR1/FPR2/FPR3 triple.  */

    deprecated_write_register_bytes (REGISTER_BYTE (FP0_REGNUM + 1), valbuf,
				     TYPE_LENGTH (type));
  else if (TYPE_CODE (type) == TYPE_CODE_ARRAY)
    {
      if (TYPE_LENGTH (type) == 16
          && TYPE_VECTOR (type))
	deprecated_write_register_bytes (REGISTER_BYTE (tdep->ppc_vr0_regnum + 2),
					 valbuf, TYPE_LENGTH (type));
    }
  else
    /* Everything else is returned in GPR3 and up.  */
    deprecated_write_register_bytes (REGISTER_BYTE (gdbarch_tdep (current_gdbarch)->ppc_gp0_regnum + 3),
				     valbuf, TYPE_LENGTH (type));
}

/* Extract from an array REGBUF containing the (raw) register state
   the address in which a function should return its structure value,
   as a CORE_ADDR (or an expression that can be used as one).  */

static CORE_ADDR
rs6000_extract_struct_value_address (struct regcache *regcache)
{
  /* FIXME: cagney/2002-09-26: PR gdb/724: When making an inferior
     function call GDB knows the address of the struct return value
     and hence, should not need to call this function.  Unfortunately,
     the current hand_function_call() code only saves the most recent
     struct address leading to occasional calls.  The code should
     instead maintain a stack of such addresses (in the dummy frame
     object).  */
  /* NOTE: cagney/2002-09-26: Return 0 which indicates that we've
     really got no idea where the return value is being stored.  While
     r3, on function entry, contained the address it will have since
     been reused (scratch) and hence wouldn't be valid */
  return 0;
}

/* Return whether PC is in a dummy function call.

   FIXME: This just checks for the end of the stack, which is broken
   for things like stepping through gcc nested function stubs.  */

static int
rs6000_pc_in_call_dummy (CORE_ADDR pc, CORE_ADDR sp, CORE_ADDR fp)
{
  return sp < pc && pc < fp;
}

/* Hook called when a new child process is started.  */

void
rs6000_create_inferior (int pid)
{
  if (rs6000_set_host_arch_hook)
    rs6000_set_host_arch_hook (pid);
}

/* Support for CONVERT_FROM_FUNC_PTR_ADDR(ADDR).

   Usually a function pointer's representation is simply the address
   of the function. On the RS/6000 however, a function pointer is
   represented by a pointer to a TOC entry. This TOC entry contains
   three words, the first word is the address of the function, the
   second word is the TOC pointer (r2), and the third word is the
   static chain value.  Throughout GDB it is currently assumed that a
   function pointer contains the address of the function, which is not
   easy to fix.  In addition, the conversion of a function address to
   a function pointer would require allocation of a TOC entry in the
   inferior's memory space, with all its drawbacks.  To be able to
   call C++ virtual methods in the inferior (which are called via
   function pointers), find_function_addr uses this function to get the
   function address from a function pointer.  */

/* Return real function address if ADDR (a function pointer) is in the data
   space and is therefore a special function pointer.  */

CORE_ADDR
rs6000_convert_from_func_ptr_addr (CORE_ADDR addr)
{
  struct obj_section *s;

  s = find_pc_section (addr);
  if (s && s->the_bfd_section->flags & SEC_CODE)
    return addr;

  /* ADDR is in the data space, so it's a special function pointer. */
  return read_memory_addr (addr, gdbarch_tdep (current_gdbarch)->wordsize);
}


/* Handling the various POWER/PowerPC variants.  */


/* The arrays here called registers_MUMBLE hold information about available
   registers.

   For each family of PPC variants, I've tried to isolate out the
   common registers and put them up front, so that as long as you get
   the general family right, GDB will correctly identify the registers
   common to that family.  The common register sets are:

   For the 60x family: hid0 hid1 iabr dabr pir

   For the 505 and 860 family: eie eid nri

   For the 403 and 403GC: icdbdr esr dear evpr cdbcr tsr tcr pit tbhi
   tblo srr2 srr3 dbsr dbcr iac1 iac2 dac1 dac2 dccr iccr pbl1
   pbu1 pbl2 pbu2

   Most of these register groups aren't anything formal.  I arrived at
   them by looking at the registers that occurred in more than one
   processor.
   
   Note: kevinb/2002-04-30: Support for the fpscr register was added
   during April, 2002.  Slot 70 is being used for PowerPC and slot 71
   for Power.  For PowerPC, slot 70 was unused and was already in the
   PPC_UISA_SPRS which is ideally where fpscr should go.  For Power,
   slot 70 was being used for "mq", so the next available slot (71)
   was chosen.  It would have been nice to be able to make the
   register numbers the same across processor cores, but this wasn't
   possible without either 1) renumbering some registers for some
   processors or 2) assigning fpscr to a really high slot that's
   larger than any current register number.  Doing (1) is bad because
   existing stubs would break.  Doing (2) is undesirable because it
   would introduce a really large gap between fpscr and the rest of
   the registers for most processors.  */

/* Convenience macros for populating register arrays.  */

/* Within another macro, convert S to a string.  */

#define STR(s)	#s

/* Return a struct reg defining register NAME that's 32 bits on 32-bit systems
   and 64 bits on 64-bit systems.  */
#define R(name)		{ STR(name), 4, 8, 0, 0 }

/* Return a struct reg defining register NAME that's 32 bits on all
   systems.  */
#define R4(name)	{ STR(name), 4, 4, 0, 0 }

/* Return a struct reg defining register NAME that's 64 bits on all
   systems.  */
#define R8(name)	{ STR(name), 8, 8, 0, 0 }

/* Return a struct reg defining register NAME that's 128 bits on all
   systems.  */
#define R16(name)       { STR(name), 16, 16, 0, 0 }

/* Return a struct reg defining floating-point register NAME.  */
#define F(name)		{ STR(name), 8, 8, 1, 0 }

/* Return a struct reg defining a pseudo register NAME.  */
#define P(name)		{ STR(name), 4, 8, 0, 1}

/* Return a struct reg defining register NAME that's 32 bits on 32-bit
   systems and that doesn't exist on 64-bit systems.  */
#define R32(name)	{ STR(name), 4, 0, 0, 0 }

/* Return a struct reg defining register NAME that's 64 bits on 64-bit
   systems and that doesn't exist on 32-bit systems.  */
#define R64(name)	{ STR(name), 0, 8, 0, 0 }

/* Return a struct reg placeholder for a register that doesn't exist.  */
#define R0		{ 0, 0, 0, 0, 0 }

/* UISA registers common across all architectures, including POWER.  */

#define COMMON_UISA_REGS \
  /*  0 */ R(r0), R(r1), R(r2), R(r3), R(r4), R(r5), R(r6), R(r7),  \
  /*  8 */ R(r8), R(r9), R(r10),R(r11),R(r12),R(r13),R(r14),R(r15), \
  /* 16 */ R(r16),R(r17),R(r18),R(r19),R(r20),R(r21),R(r22),R(r23), \
  /* 24 */ R(r24),R(r25),R(r26),R(r27),R(r28),R(r29),R(r30),R(r31), \
  /* 32 */ F(f0), F(f1), F(f2), F(f3), F(f4), F(f5), F(f6), F(f7),  \
  /* 40 */ F(f8), F(f9), F(f10),F(f11),F(f12),F(f13),F(f14),F(f15), \
  /* 48 */ F(f16),F(f17),F(f18),F(f19),F(f20),F(f21),F(f22),F(f23), \
  /* 56 */ F(f24),F(f25),F(f26),F(f27),F(f28),F(f29),F(f30),F(f31), \
  /* 64 */ R(pc), R(ps)

#define COMMON_UISA_NOFP_REGS \
  /*  0 */ R(r0), R(r1), R(r2), R(r3), R(r4), R(r5), R(r6), R(r7),  \
  /*  8 */ R(r8), R(r9), R(r10),R(r11),R(r12),R(r13),R(r14),R(r15), \
  /* 16 */ R(r16),R(r17),R(r18),R(r19),R(r20),R(r21),R(r22),R(r23), \
  /* 24 */ R(r24),R(r25),R(r26),R(r27),R(r28),R(r29),R(r30),R(r31), \
  /* 32 */ R0,    R0,    R0,    R0,    R0,    R0,    R0,    R0,     \
  /* 40 */ R0,    R0,    R0,    R0,    R0,    R0,    R0,    R0,     \
  /* 48 */ R0,    R0,    R0,    R0,    R0,    R0,    R0,    R0,     \
  /* 56 */ R0,    R0,    R0,    R0,    R0,    R0,    R0,    R0,     \
  /* 64 */ R(pc), R(ps)

/* UISA-level SPRs for PowerPC.  */
#define PPC_UISA_SPRS \
  /* 66 */ R4(cr),  R(lr), R(ctr), R4(xer), R4(fpscr)

/* UISA-level SPRs for PowerPC without floating point support.  */
#define PPC_UISA_NOFP_SPRS \
  /* 66 */ R4(cr),  R(lr), R(ctr), R4(xer), R0

/* Segment registers, for PowerPC.  */
#define PPC_SEGMENT_REGS \
  /* 71 */ R32(sr0),  R32(sr1),  R32(sr2),  R32(sr3),  \
  /* 75 */ R32(sr4),  R32(sr5),  R32(sr6),  R32(sr7),  \
  /* 79 */ R32(sr8),  R32(sr9),  R32(sr10), R32(sr11), \
  /* 83 */ R32(sr12), R32(sr13), R32(sr14), R32(sr15)

/* OEA SPRs for PowerPC.  */
#define PPC_OEA_SPRS \
  /*  87 */ R4(pvr), \
  /*  88 */ R(ibat0u), R(ibat0l), R(ibat1u), R(ibat1l), \
  /*  92 */ R(ibat2u), R(ibat2l), R(ibat3u), R(ibat3l), \
  /*  96 */ R(dbat0u), R(dbat0l), R(dbat1u), R(dbat1l), \
  /* 100 */ R(dbat2u), R(dbat2l), R(dbat3u), R(dbat3l), \
  /* 104 */ R(sdr1),   R64(asr),  R(dar),    R4(dsisr), \
  /* 108 */ R(sprg0),  R(sprg1),  R(sprg2),  R(sprg3),  \
  /* 112 */ R(srr0),   R(srr1),   R(tbl),    R(tbu),    \
  /* 116 */ R4(dec),   R(dabr),   R4(ear)

/* AltiVec registers.  */
#define PPC_ALTIVEC_REGS \
  /*119*/R16(vr0), R16(vr1), R16(vr2), R16(vr3), R16(vr4), R16(vr5), R16(vr6), R16(vr7),  \
  /*127*/R16(vr8), R16(vr9), R16(vr10),R16(vr11),R16(vr12),R16(vr13),R16(vr14),R16(vr15), \
  /*135*/R16(vr16),R16(vr17),R16(vr18),R16(vr19),R16(vr20),R16(vr21),R16(vr22),R16(vr23), \
  /*143*/R16(vr24),R16(vr25),R16(vr26),R16(vr27),R16(vr28),R16(vr29),R16(vr30),R16(vr31), \
  /*151*/R4(vscr), R4(vrsave)

/* Vectors of hi-lo general purpose registers.  */
#define PPC_EV_REGS \
  /* 0*/R8(ev0), R8(ev1), R8(ev2), R8(ev3), R8(ev4), R8(ev5), R8(ev6), R8(ev7),  \
  /* 8*/R8(ev8), R8(ev9), R8(ev10),R8(ev11),R8(ev12),R8(ev13),R8(ev14),R8(ev15), \
  /*16*/R8(ev16),R8(ev17),R8(ev18),R8(ev19),R8(ev20),R8(ev21),R8(ev22),R8(ev23), \
  /*24*/R8(ev24),R8(ev25),R8(ev26),R8(ev27),R8(ev28),R8(ev29),R8(ev30),R8(ev31)

/* Lower half of the EV registers.  */
#define PPC_GPRS_PSEUDO_REGS \
  /*  0 */ P(r0), P(r1), P(r2), P(r3), P(r4), P(r5), P(r6), P(r7),  \
  /*  8 */ P(r8), P(r9), P(r10),P(r11),P(r12),P(r13),P(r14),P(r15), \
  /* 16 */ P(r16),P(r17),P(r18),P(r19),P(r20),P(r21),P(r22),P(r23), \
  /* 24 */ P(r24),P(r25),P(r26),P(r27),P(r28),P(r29),P(r30),P(r31)

/* IBM POWER (pre-PowerPC) architecture, user-level view.  We only cover
   user-level SPR's.  */
static const struct reg registers_power[] =
{
  COMMON_UISA_REGS,
  /* 66 */ R4(cnd), R(lr), R(cnt), R4(xer), R4(mq),
  /* 71 */ R4(fpscr)
};

/* PowerPC UISA - a PPC processor as viewed by user-level code.  A UISA-only
   view of the PowerPC.  */
static const struct reg registers_powerpc[] =
{
  COMMON_UISA_REGS,
  PPC_UISA_SPRS,
  PPC_ALTIVEC_REGS
};

/* PowerPC UISA - a PPC processor as viewed by user-level
   code, but without floating point registers.  */
static const struct reg registers_powerpc_nofp[] =
{
  COMMON_UISA_NOFP_REGS,
  PPC_UISA_SPRS
};

/* IBM PowerPC 403.  */
static const struct reg registers_403[] =
{
  COMMON_UISA_REGS,
  PPC_UISA_SPRS,
  PPC_SEGMENT_REGS,
  PPC_OEA_SPRS,
  /* 119 */ R(icdbdr), R(esr),  R(dear), R(evpr),
  /* 123 */ R(cdbcr),  R(tsr),  R(tcr),  R(pit),
  /* 127 */ R(tbhi),   R(tblo), R(srr2), R(srr3),
  /* 131 */ R(dbsr),   R(dbcr), R(iac1), R(iac2),
  /* 135 */ R(dac1),   R(dac2), R(dccr), R(iccr),
  /* 139 */ R(pbl1),   R(pbu1), R(pbl2), R(pbu2)
};

/* IBM PowerPC 403GC.  */
static const struct reg registers_403GC[] =
{
  COMMON_UISA_REGS,
  PPC_UISA_SPRS,
  PPC_SEGMENT_REGS,
  PPC_OEA_SPRS,
  /* 119 */ R(icdbdr), R(esr),  R(dear), R(evpr),
  /* 123 */ R(cdbcr),  R(tsr),  R(tcr),  R(pit),
  /* 127 */ R(tbhi),   R(tblo), R(srr2), R(srr3),
  /* 131 */ R(dbsr),   R(dbcr), R(iac1), R(iac2),
  /* 135 */ R(dac1),   R(dac2), R(dccr), R(iccr),
  /* 139 */ R(pbl1),   R(pbu1), R(pbl2), R(pbu2),
  /* 143 */ R(zpr),    R(pid),  R(sgr),  R(dcwr),
  /* 147 */ R(tbhu),   R(tblu)
};

/* Motorola PowerPC 505.  */
static const struct reg registers_505[] =
{
  COMMON_UISA_REGS,
  PPC_UISA_SPRS,
  PPC_SEGMENT_REGS,
  PPC_OEA_SPRS,
  /* 119 */ R(eie), R(eid), R(nri)
};

/* Motorola PowerPC 860 or 850.  */
static const struct reg registers_860[] =
{
  COMMON_UISA_REGS,
  PPC_UISA_SPRS,
  PPC_SEGMENT_REGS,
  PPC_OEA_SPRS,
  /* 119 */ R(eie), R(eid), R(nri), R(cmpa),
  /* 123 */ R(cmpb), R(cmpc), R(cmpd), R(icr),
  /* 127 */ R(der), R(counta), R(countb), R(cmpe),
  /* 131 */ R(cmpf), R(cmpg), R(cmph), R(lctrl1),
  /* 135 */ R(lctrl2), R(ictrl), R(bar), R(ic_cst),
  /* 139 */ R(ic_adr), R(ic_dat), R(dc_cst), R(dc_adr),
  /* 143 */ R(dc_dat), R(dpdr), R(dpir), R(immr),
  /* 147 */ R(mi_ctr), R(mi_ap), R(mi_epn), R(mi_twc),
  /* 151 */ R(mi_rpn), R(md_ctr), R(m_casid), R(md_ap),
  /* 155 */ R(md_epn), R(md_twb), R(md_twc), R(md_rpn),
  /* 159 */ R(m_tw), R(mi_dbcam), R(mi_dbram0), R(mi_dbram1),
  /* 163 */ R(md_dbcam), R(md_dbram0), R(md_dbram1)
};

/* Motorola PowerPC 601.  Note that the 601 has different register numbers
   for reading and writing RTCU and RTCL.  However, how one reads and writes a
   register is the stub's problem.  */
static const struct reg registers_601[] =
{
  COMMON_UISA_REGS,
  PPC_UISA_SPRS,
  PPC_SEGMENT_REGS,
  PPC_OEA_SPRS,
  /* 119 */ R(hid0), R(hid1), R(iabr), R(dabr),
  /* 123 */ R(pir), R(mq), R(rtcu), R(rtcl)
};

/* Motorola PowerPC 602.  */
static const struct reg registers_602[] =
{
  COMMON_UISA_REGS,
  PPC_UISA_SPRS,
  PPC_SEGMENT_REGS,
  PPC_OEA_SPRS,
  /* 119 */ R(hid0), R(hid1), R(iabr), R0,
  /* 123 */ R0, R(tcr), R(ibr), R(esassr),
  /* 127 */ R(sebr), R(ser), R(sp), R(lt)
};

/* Motorola/IBM PowerPC 603 or 603e.  */
static const struct reg registers_603[] =
{
  COMMON_UISA_REGS,
  PPC_UISA_SPRS,
  PPC_SEGMENT_REGS,
  PPC_OEA_SPRS,
  /* 119 */ R(hid0), R(hid1), R(iabr), R0,
  /* 123 */ R0, R(dmiss), R(dcmp), R(hash1),
  /* 127 */ R(hash2), R(imiss), R(icmp), R(rpa)
};

/* Motorola PowerPC 604 or 604e.  */
static const struct reg registers_604[] =
{
  COMMON_UISA_REGS,
  PPC_UISA_SPRS,
  PPC_SEGMENT_REGS,
  PPC_OEA_SPRS,
  /* 119 */ R(hid0), R(hid1), R(iabr), R(dabr),
  /* 123 */ R(pir), R(mmcr0), R(pmc1), R(pmc2),
  /* 127 */ R(sia), R(sda)
};

/* Motorola/IBM PowerPC 750 or 740.  */
static const struct reg registers_750[] =
{
  COMMON_UISA_REGS,
  PPC_UISA_SPRS,
  PPC_SEGMENT_REGS,
  PPC_OEA_SPRS,
  /* 119 */ R(hid0), R(hid1), R(iabr), R(dabr),
  /* 123 */ R0, R(ummcr0), R(upmc1), R(upmc2),
  /* 127 */ R(usia), R(ummcr1), R(upmc3), R(upmc4),
  /* 131 */ R(mmcr0), R(pmc1), R(pmc2), R(sia),
  /* 135 */ R(mmcr1), R(pmc3), R(pmc4), R(l2cr),
  /* 139 */ R(ictc), R(thrm1), R(thrm2), R(thrm3)
};


/* Motorola PowerPC 7400.  */
static const struct reg registers_7400[] =
{
  /* gpr0-gpr31, fpr0-fpr31 */
  COMMON_UISA_REGS,
  /* ctr, xre, lr, cr */
  PPC_UISA_SPRS,
  /* sr0-sr15 */
  PPC_SEGMENT_REGS,
  PPC_OEA_SPRS,
  /* vr0-vr31, vrsave, vscr */
  PPC_ALTIVEC_REGS
  /* FIXME? Add more registers? */
};

/* Motorola e500.  */
static const struct reg registers_e500[] =
{
  R(pc), R(ps),
  /* cr, lr, ctr, xer, "" */
  PPC_UISA_NOFP_SPRS,
  /* 7...38 */
  PPC_EV_REGS,
  R8(acc), R(spefscr),
  /* NOTE: Add new registers here the end of the raw register
     list and just before the first pseudo register.  */
  /* 39...70 */
  PPC_GPRS_PSEUDO_REGS
};

/* Information about a particular processor variant.  */

struct variant
  {
    /* Name of this variant.  */
    char *name;

    /* English description of the variant.  */
    char *description;

    /* bfd_arch_info.arch corresponding to variant.  */
    enum bfd_architecture arch;

    /* bfd_arch_info.mach corresponding to variant.  */
    unsigned long mach;

    /* Number of real registers.  */
    int nregs;

    /* Number of pseudo registers.  */
    int npregs;

    /* Number of total registers (the sum of nregs and npregs).  */
    int num_tot_regs;

    /* Table of register names; registers[R] is the name of the register
       number R.  */
    const struct reg *regs;
  };

#define tot_num_registers(list) (sizeof (list) / sizeof((list)[0]))

static int
num_registers (const struct reg *reg_list, int num_tot_regs)
{
  int i;
  int nregs = 0;

  for (i = 0; i < num_tot_regs; i++)
    if (!reg_list[i].pseudo)
      nregs++;
       
  return nregs;
}

static int
num_pseudo_registers (const struct reg *reg_list, int num_tot_regs)
{
  int i;
  int npregs = 0;

  for (i = 0; i < num_tot_regs; i++)
    if (reg_list[i].pseudo)
      npregs ++; 

  return npregs;
}

/* Information in this table comes from the following web sites:
   IBM:       http://www.chips.ibm.com:80/products/embedded/
   Motorola:  http://www.mot.com/SPS/PowerPC/

   I'm sure I've got some of the variant descriptions not quite right.
   Please report any inaccuracies you find to GDB's maintainer.

   If you add entries to this table, please be sure to allow the new
   value as an argument to the --with-cpu flag, in configure.in.  */

static struct variant variants[] =
{

  {"powerpc", "PowerPC user-level", bfd_arch_powerpc,
   bfd_mach_ppc, -1, -1, tot_num_registers (registers_powerpc),
   registers_powerpc},
  {"power", "POWER user-level", bfd_arch_rs6000,
   bfd_mach_rs6k, -1, -1, tot_num_registers (registers_power),
   registers_power},
  {"403", "IBM PowerPC 403", bfd_arch_powerpc,
   bfd_mach_ppc_403, -1, -1, tot_num_registers (registers_403),
   registers_403},
  {"601", "Motorola PowerPC 601", bfd_arch_powerpc,
   bfd_mach_ppc_601, -1, -1, tot_num_registers (registers_601),
   registers_601},
  {"602", "Motorola PowerPC 602", bfd_arch_powerpc,
   bfd_mach_ppc_602, -1, -1, tot_num_registers (registers_602),
   registers_602},
  {"603", "Motorola/IBM PowerPC 603 or 603e", bfd_arch_powerpc,
   bfd_mach_ppc_603, -1, -1, tot_num_registers (registers_603),
   registers_603},
  {"604", "Motorola PowerPC 604 or 604e", bfd_arch_powerpc,
   604, -1, -1, tot_num_registers (registers_604),
   registers_604},
  {"403GC", "IBM PowerPC 403GC", bfd_arch_powerpc,
   bfd_mach_ppc_403gc, -1, -1, tot_num_registers (registers_403GC),
   registers_403GC},
  {"505", "Motorola PowerPC 505", bfd_arch_powerpc,
   bfd_mach_ppc_505, -1, -1, tot_num_registers (registers_505),
   registers_505},
  {"860", "Motorola PowerPC 860 or 850", bfd_arch_powerpc,
   bfd_mach_ppc_860, -1, -1, tot_num_registers (registers_860),
   registers_860},
  {"750", "Motorola/IBM PowerPC 750 or 740", bfd_arch_powerpc,
   bfd_mach_ppc_750, -1, -1, tot_num_registers (registers_750),
   registers_750},
  {"7400", "Motorola/IBM PowerPC 7400 (G4)", bfd_arch_powerpc,
   bfd_mach_ppc_7400, -1, -1, tot_num_registers (registers_7400),
   registers_7400},
  {"e500", "Motorola PowerPC e500", bfd_arch_powerpc,
   bfd_mach_ppc_e500, -1, -1, tot_num_registers (registers_e500),
   registers_e500},

  /* 64-bit */
  {"powerpc64", "PowerPC 64-bit user-level", bfd_arch_powerpc,
   bfd_mach_ppc64, -1, -1, tot_num_registers (registers_powerpc),
   registers_powerpc},
  {"620", "Motorola PowerPC 620", bfd_arch_powerpc,
   bfd_mach_ppc_620, -1, -1, tot_num_registers (registers_powerpc),
   registers_powerpc},
  {"630", "Motorola PowerPC 630", bfd_arch_powerpc,
   bfd_mach_ppc_630, -1, -1, tot_num_registers (registers_powerpc),
   registers_powerpc},
  {"a35", "PowerPC A35", bfd_arch_powerpc,
   bfd_mach_ppc_a35, -1, -1, tot_num_registers (registers_powerpc),
   registers_powerpc},
  {"rs64ii", "PowerPC rs64ii", bfd_arch_powerpc,
   bfd_mach_ppc_rs64ii, -1, -1, tot_num_registers (registers_powerpc),
   registers_powerpc},
  {"rs64iii", "PowerPC rs64iii", bfd_arch_powerpc,
   bfd_mach_ppc_rs64iii, -1, -1, tot_num_registers (registers_powerpc),
   registers_powerpc},

  /* FIXME: I haven't checked the register sets of the following.  */
  {"rs1", "IBM POWER RS1", bfd_arch_rs6000,
   bfd_mach_rs6k_rs1, -1, -1, tot_num_registers (registers_power),
   registers_power},
  {"rsc", "IBM POWER RSC", bfd_arch_rs6000,
   bfd_mach_rs6k_rsc, -1, -1, tot_num_registers (registers_power),
   registers_power},
  {"rs2", "IBM POWER RS2", bfd_arch_rs6000,
   bfd_mach_rs6k_rs2, -1, -1, tot_num_registers (registers_power),
   registers_power},

  {0, 0, 0, 0, 0, 0, 0, 0}
};

/* Initialize the number of registers and pseudo registers in each variant.  */

static void
init_variants (void)
{
  struct variant *v;

  for (v = variants; v->name; v++)
    {
      if (v->nregs == -1)
        v->nregs = num_registers (v->regs, v->num_tot_regs);
      if (v->npregs == -1)
        v->npregs = num_pseudo_registers (v->regs, v->num_tot_regs);
    }  
}

/* Return the variant corresponding to architecture ARCH and machine number
   MACH.  If no such variant exists, return null.  */

static const struct variant *
find_variant_by_arch (enum bfd_architecture arch, unsigned long mach)
{
  const struct variant *v;

  for (v = variants; v->name; v++)
    if (arch == v->arch && mach == v->mach)
      return v;

  return NULL;
}

static int
gdb_print_insn_powerpc (bfd_vma memaddr, disassemble_info *info)
{
  if (TARGET_BYTE_ORDER == BFD_ENDIAN_BIG)
    return print_insn_big_powerpc (memaddr, info);
  else
    return print_insn_little_powerpc (memaddr, info);
}

/* Initialize the current architecture based on INFO.  If possible, re-use an
   architecture from ARCHES, which is a list of architectures already created
   during this debugging session.

   Called e.g. at program startup, when reading a core file, and when reading
   a binary file.  */

static struct gdbarch *
rs6000_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
{
  struct gdbarch *gdbarch;
  struct gdbarch_tdep *tdep;
  int wordsize, from_xcoff_exec, from_elf_exec, power, i, off;
  struct reg *regs;
  const struct variant *v;
  enum bfd_architecture arch;
  unsigned long mach;
  bfd abfd;
  int sysv_abi;
  asection *sect;

  from_xcoff_exec = info.abfd && info.abfd->format == bfd_object &&
    bfd_get_flavour (info.abfd) == bfd_target_xcoff_flavour;

  from_elf_exec = info.abfd && info.abfd->format == bfd_object &&
    bfd_get_flavour (info.abfd) == bfd_target_elf_flavour;

  sysv_abi = info.abfd && bfd_get_flavour (info.abfd) == bfd_target_elf_flavour;

  /* Check word size.  If INFO is from a binary file, infer it from
     that, else choose a likely default.  */
  if (from_xcoff_exec)
    {
      if (bfd_xcoff_is_xcoff64 (info.abfd))
	wordsize = 8;
      else
	wordsize = 4;
    }
  else if (from_elf_exec)
    {
      if (elf_elfheader (info.abfd)->e_ident[EI_CLASS] == ELFCLASS64)
	wordsize = 8;
      else
	wordsize = 4;
    }
  else
    {
      if (info.bfd_arch_info != NULL && info.bfd_arch_info->bits_per_word != 0)
	wordsize = info.bfd_arch_info->bits_per_word /
	  info.bfd_arch_info->bits_per_byte;
      else
	wordsize = 4;
    }

  /* Find a candidate among extant architectures.  */
  for (arches = gdbarch_list_lookup_by_info (arches, &info);
       arches != NULL;
       arches = gdbarch_list_lookup_by_info (arches->next, &info))
    {
      /* Word size in the various PowerPC bfd_arch_info structs isn't
         meaningful, because 64-bit CPUs can run in 32-bit mode.  So, perform
         separate word size check.  */
      tdep = gdbarch_tdep (arches->gdbarch);
      if (tdep && tdep->wordsize == wordsize)
	return arches->gdbarch;
    }

  /* None found, create a new architecture from INFO, whose bfd_arch_info
     validity depends on the source:
       - executable		useless
       - rs6000_host_arch()	good
       - core file		good
       - "set arch"		trust blindly
       - GDB startup		useless but harmless */

  if (!from_xcoff_exec)
    {
      arch = info.bfd_arch_info->arch;
      mach = info.bfd_arch_info->mach;
    }
  else
    {
      arch = bfd_arch_powerpc;
      mach = 0;
      bfd_default_set_arch_mach (&abfd, arch, mach);
      info.bfd_arch_info = bfd_get_arch_info (&abfd);
    }
  tdep = xmalloc (sizeof (struct gdbarch_tdep));
  tdep->wordsize = wordsize;

  /* For e500 executables, the apuinfo section is of help here.  Such
     section contains the identifier and revision number of each
     Application-specific Processing Unit that is present on the
     chip.  The content of the section is determined by the assembler
     which looks at each instruction and determines which unit (and
     which version of it) can execute it. In our case we just look for
     the existance of the section.  */

  if (info.abfd)
    {
      sect = bfd_get_section_by_name (info.abfd, ".PPC.EMB.apuinfo");
      if (sect)
	{
	  arch = info.bfd_arch_info->arch;
	  mach = bfd_mach_ppc_e500;
	  bfd_default_set_arch_mach (&abfd, arch, mach);
	  info.bfd_arch_info = bfd_get_arch_info (&abfd);
	}
    }

  gdbarch = gdbarch_alloc (&info, tdep);
  power = arch == bfd_arch_rs6000;

  /* Initialize the number of real and pseudo registers in each variant.  */
  init_variants ();

  /* Choose variant.  */
  v = find_variant_by_arch (arch, mach);
  if (!v)
    return NULL;

  tdep->regs = v->regs;

  tdep->ppc_gp0_regnum = 0;
  tdep->ppc_gplast_regnum = 31;
  tdep->ppc_toc_regnum = 2;
  tdep->ppc_ps_regnum = 65;
  tdep->ppc_cr_regnum = 66;
  tdep->ppc_lr_regnum = 67;
  tdep->ppc_ctr_regnum = 68;
  tdep->ppc_xer_regnum = 69;
  if (v->mach == bfd_mach_ppc_601)
    tdep->ppc_mq_regnum = 124;
  else if (power)
    tdep->ppc_mq_regnum = 70;
  else
    tdep->ppc_mq_regnum = -1;
  tdep->ppc_fpscr_regnum = power ? 71 : 70;

  set_gdbarch_pc_regnum (gdbarch, 64);
  set_gdbarch_sp_regnum (gdbarch, 1);
  set_gdbarch_fp_regnum (gdbarch, 1);
  set_gdbarch_deprecated_extract_return_value (gdbarch,
					       rs6000_extract_return_value);
  set_gdbarch_deprecated_store_return_value (gdbarch, rs6000_store_return_value);

  if (v->arch == bfd_arch_powerpc)
    switch (v->mach)
      {
      case bfd_mach_ppc: 
	tdep->ppc_vr0_regnum = 71;
	tdep->ppc_vrsave_regnum = 104;
	tdep->ppc_ev0_regnum = -1;
	tdep->ppc_ev31_regnum = -1;
	break;
      case bfd_mach_ppc_7400:
	tdep->ppc_vr0_regnum = 119;
	tdep->ppc_vrsave_regnum = 152;
	tdep->ppc_ev0_regnum = -1;
	tdep->ppc_ev31_regnum = -1;
	break;
      case bfd_mach_ppc_e500:
        tdep->ppc_gp0_regnum = 41;
        tdep->ppc_gplast_regnum = tdep->ppc_gp0_regnum + 32 - 1;
        tdep->ppc_toc_regnum = -1;
        tdep->ppc_ps_regnum = 1;
        tdep->ppc_cr_regnum = 2;
        tdep->ppc_lr_regnum = 3;
        tdep->ppc_ctr_regnum = 4;
        tdep->ppc_xer_regnum = 5;
	tdep->ppc_ev0_regnum = 7;
	tdep->ppc_ev31_regnum = 38;
        set_gdbarch_pc_regnum (gdbarch, 0);
        set_gdbarch_sp_regnum (gdbarch, tdep->ppc_gp0_regnum + 1);
        set_gdbarch_fp_regnum (gdbarch, tdep->ppc_gp0_regnum + 1);
        set_gdbarch_dwarf2_reg_to_regnum (gdbarch, e500_dwarf2_reg_to_regnum);
        set_gdbarch_pseudo_register_read (gdbarch, e500_pseudo_register_read);
        set_gdbarch_pseudo_register_write (gdbarch, e500_pseudo_register_write);
        set_gdbarch_extract_return_value (gdbarch, e500_extract_return_value);
        set_gdbarch_deprecated_store_return_value (gdbarch, e500_store_return_value);
	break;
      default:
	tdep->ppc_vr0_regnum = -1;
	tdep->ppc_vrsave_regnum = -1;
	tdep->ppc_ev0_regnum = -1;
	tdep->ppc_ev31_regnum = -1;
	break;
      }   

  /* Sanity check on registers.  */
  gdb_assert (strcmp (tdep->regs[tdep->ppc_gp0_regnum].name, "r0") == 0);

  /* Set lr_frame_offset.  */
  if (wordsize == 8)
    tdep->lr_frame_offset = 16;
  else if (sysv_abi)
    tdep->lr_frame_offset = 4;
  else
    tdep->lr_frame_offset = 8;

  /* Calculate byte offsets in raw register array.  */
  tdep->regoff = xmalloc (v->num_tot_regs * sizeof (int));
  for (i = off = 0; i < v->num_tot_regs; i++)
    {
      tdep->regoff[i] = off;
      off += regsize (v->regs + i, wordsize);
    }

  /* Select instruction printer.  */
  if (arch == power)
    set_gdbarch_print_insn (gdbarch, print_insn_rs6000);
  else
    set_gdbarch_print_insn (gdbarch, gdb_print_insn_powerpc);

  set_gdbarch_read_pc (gdbarch, generic_target_read_pc);
  set_gdbarch_write_pc (gdbarch, generic_target_write_pc);
  set_gdbarch_read_fp (gdbarch, generic_target_read_fp);
  set_gdbarch_read_sp (gdbarch, generic_target_read_sp);
  set_gdbarch_write_sp (gdbarch, generic_target_write_sp);

  set_gdbarch_num_regs (gdbarch, v->nregs);
  set_gdbarch_num_pseudo_regs (gdbarch, v->npregs);
  set_gdbarch_register_name (gdbarch, rs6000_register_name);
  set_gdbarch_register_size (gdbarch, wordsize);
  set_gdbarch_register_bytes (gdbarch, off);
  set_gdbarch_register_byte (gdbarch, rs6000_register_byte);
  set_gdbarch_register_raw_size (gdbarch, rs6000_register_raw_size);
  set_gdbarch_max_register_raw_size (gdbarch, 16);
  set_gdbarch_register_virtual_size (gdbarch, generic_register_size);
  set_gdbarch_max_register_virtual_size (gdbarch, 16);
  set_gdbarch_register_virtual_type (gdbarch, rs6000_register_virtual_type);

  set_gdbarch_ptr_bit (gdbarch, wordsize * TARGET_CHAR_BIT);
  set_gdbarch_short_bit (gdbarch, 2 * TARGET_CHAR_BIT);
  set_gdbarch_int_bit (gdbarch, 4 * TARGET_CHAR_BIT);
  set_gdbarch_long_bit (gdbarch, wordsize * TARGET_CHAR_BIT);
  set_gdbarch_long_long_bit (gdbarch, 8 * TARGET_CHAR_BIT);
  set_gdbarch_float_bit (gdbarch, 4 * TARGET_CHAR_BIT);
  set_gdbarch_double_bit (gdbarch, 8 * TARGET_CHAR_BIT);
  set_gdbarch_long_double_bit (gdbarch, 8 * TARGET_CHAR_BIT);
  set_gdbarch_char_signed (gdbarch, 0);

  set_gdbarch_call_dummy_length (gdbarch, 0);
  set_gdbarch_call_dummy_address (gdbarch, entry_point_address);
  set_gdbarch_call_dummy_breakpoint_offset_p (gdbarch, 1);
  set_gdbarch_call_dummy_breakpoint_offset (gdbarch, 0);
  set_gdbarch_call_dummy_start_offset (gdbarch, 0);
  set_gdbarch_call_dummy_p (gdbarch, 1);
  set_gdbarch_call_dummy_stack_adjust_p (gdbarch, 0);
  set_gdbarch_fix_call_dummy (gdbarch, rs6000_fix_call_dummy);
  set_gdbarch_frame_align (gdbarch, rs6000_frame_align);
  set_gdbarch_save_dummy_frame_tos (gdbarch, generic_save_dummy_frame_tos);
  set_gdbarch_push_return_address (gdbarch, ppc_push_return_address);
  set_gdbarch_believe_pcc_promotion (gdbarch, 1);

  set_gdbarch_register_convertible (gdbarch, rs6000_register_convertible);
  set_gdbarch_register_convert_to_virtual (gdbarch, rs6000_register_convert_to_virtual);
  set_gdbarch_register_convert_to_raw (gdbarch, rs6000_register_convert_to_raw);
  set_gdbarch_stab_reg_to_regnum (gdbarch, rs6000_stab_reg_to_regnum);
  /* Note: kevinb/2002-04-12: I'm not convinced that rs6000_push_arguments()
     is correct for the SysV ABI when the wordsize is 8, but I'm also
     fairly certain that ppc_sysv_abi_push_arguments() will give even
     worse results since it only works for 32-bit code.  So, for the moment,
     we're better off calling rs6000_push_arguments() since it works for
     64-bit code.  At some point in the future, this matter needs to be
     revisited.  */
  if (sysv_abi && wordsize == 4)
    set_gdbarch_push_arguments (gdbarch, ppc_sysv_abi_push_arguments);
  else
    set_gdbarch_push_arguments (gdbarch, rs6000_push_arguments);

  set_gdbarch_store_struct_return (gdbarch, rs6000_store_struct_return);
  set_gdbarch_extract_struct_value_address (gdbarch, rs6000_extract_struct_value_address);
  set_gdbarch_pop_frame (gdbarch, rs6000_pop_frame);

  set_gdbarch_skip_prologue (gdbarch, rs6000_skip_prologue);
  set_gdbarch_inner_than (gdbarch, core_addr_lessthan);
  set_gdbarch_decr_pc_after_break (gdbarch, 0);
  set_gdbarch_function_start_offset (gdbarch, 0);
  set_gdbarch_breakpoint_from_pc (gdbarch, rs6000_breakpoint_from_pc);

  /* Not sure on this. FIXMEmgo */
  set_gdbarch_frame_args_skip (gdbarch, 8);

  if (sysv_abi)
    set_gdbarch_use_struct_convention (gdbarch,
    				       ppc_sysv_abi_use_struct_convention);
  else
    set_gdbarch_use_struct_convention (gdbarch,
				       generic_use_struct_convention);

  set_gdbarch_frameless_function_invocation (gdbarch,
                                         rs6000_frameless_function_invocation);
  set_gdbarch_frame_chain (gdbarch, rs6000_frame_chain);
  set_gdbarch_frame_saved_pc (gdbarch, rs6000_frame_saved_pc);

  set_gdbarch_deprecated_frame_init_saved_regs (gdbarch, rs6000_frame_init_saved_regs);
  set_gdbarch_deprecated_init_extra_frame_info (gdbarch, rs6000_init_extra_frame_info);

  if (!sysv_abi)
    {
      /* Handle RS/6000 function pointers (which are really function
         descriptors).  */
      set_gdbarch_convert_from_func_ptr_addr (gdbarch,
	rs6000_convert_from_func_ptr_addr);
    }
  set_gdbarch_frame_args_address (gdbarch, rs6000_frame_args_address);
  set_gdbarch_frame_locals_address (gdbarch, rs6000_frame_args_address);
  set_gdbarch_saved_pc_after_call (gdbarch, rs6000_saved_pc_after_call);

  /* We can't tell how many args there are
     now that the C compiler delays popping them.  */
  set_gdbarch_frame_num_args (gdbarch, frame_num_args_unknown);

  /* Hook in ABI-specific overrides, if they have been registered.  */
  gdbarch_init_osabi (info, gdbarch);

  return gdbarch;
}

static void
rs6000_dump_tdep (struct gdbarch *current_gdbarch, struct ui_file *file)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);

  if (tdep == NULL)
    return;

  /* FIXME: Dump gdbarch_tdep.  */
}

static struct cmd_list_element *info_powerpc_cmdlist = NULL;

static void
rs6000_info_powerpc_command (char *args, int from_tty)
{
  help_list (info_powerpc_cmdlist, "info powerpc ", class_info, gdb_stdout);
}

/* Initialization code.  */

void
_initialize_rs6000_tdep (void)
{
  gdbarch_register (bfd_arch_rs6000, rs6000_gdbarch_init, rs6000_dump_tdep);
  gdbarch_register (bfd_arch_powerpc, rs6000_gdbarch_init, rs6000_dump_tdep);

  /* Add root prefix command for "info powerpc" commands */
  add_prefix_cmd ("powerpc", class_info, rs6000_info_powerpc_command,
		  "Various POWERPC info specific commands.",
		  &info_powerpc_cmdlist, "info powerpc ", 0, &infolist);
}