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/* Target-dependent code for the Renesas RX for GDB, the GNU debugger.

   Copyright (C) 2008, 2009, 2010 Free Software Foundation, Inc.

   Contributed by Red Hat, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3 of the License, or

   (at your option) any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"

#include "arch-utils.h"

#include "prologue-value.h"

#include "target.h"

#include "regcache.h"

#include "opcode/rx.h"

#include "dis-asm.h"

#include "gdbtypes.h"

#include "frame.h"

#include "frame-unwind.h"

#include "frame-base.h"

#include "value.h"

#include "gdbcore.h"

#include "dwarf2-frame.h"

#include "elf/rx.h"

#include "elf-bfd.h"

/* Certain important register numbers.  */

enum

{

  RX_SP_REGNUM = 0,

  RX_R1_REGNUM = 1,

  RX_R4_REGNUM = 4,

  RX_FP_REGNUM = 6,

  RX_R15_REGNUM = 15,

  RX_PC_REGNUM = 19,

  RX_NUM_REGS = 25

};

/* Architecture specific data.  */

struct gdbarch_tdep

{

  /* The ELF header flags specify the multilib used.  */

  int elf_flags;

};

/* This structure holds the results of a prologue analysis.  */

struct rx_prologue

{

  /* The offset from the frame base to the stack pointer --- always

     zero or negative.

     Calling this a "size" is a bit misleading, but given that the

     stack grows downwards, using offsets for everything keeps one

     from going completely sign-crazy: you never change anything's

     sign for an ADD instruction; always change the second operand's

     sign for a SUB instruction; and everything takes care of

     itself.  */

  int frame_size;

  /* Non-zero if this function has initialized the frame pointer from

     the stack pointer, zero otherwise.  */

  int has_frame_ptr;

  /* If has_frame_ptr is non-zero, this is the offset from the frame

     base to where the frame pointer points.  This is always zero or

     negative.  */

  int frame_ptr_offset;

  /* The address of the first instruction at which the frame has been

     set up and the arguments are where the debug info says they are

     --- as best as we can tell.  */

  CORE_ADDR prologue_end;

  /* reg_offset[R] is the offset from the CFA at which register R is

     saved, or 1 if register R has not been saved.  (Real values are

     always zero or negative.)  */

  int reg_offset[RX_NUM_REGS];

};

/* Implement the "register_name" gdbarch method.  */

static const char *

rx_register_name (struct gdbarch *gdbarch, int regnr)

{

  static const char *const reg_names[] = {

    "r0",

    "r1",

    "r2",

    "r3",

    "r4",

    "r5",

    "r6",

    "r7",

    "r8",

    "r9",

    "r10",

    "r11",

    "r12",

    "r13",

    "r14",

    "r15",

    "isp",

    "usp",

    "intb",

    "pc",

    "psw",

    "bpc",

    "bpsw",

    "vct",

    "fpsw"

  };

  return reg_names[regnr];

}

/* Implement the "register_type" gdbarch method.  */

static struct type *

rx_register_type (struct gdbarch *gdbarch, int reg_nr)

{

  if (reg_nr == RX_PC_REGNUM)

    return builtin_type (gdbarch)->builtin_func_ptr;

  else

    return builtin_type (gdbarch)->builtin_unsigned_long;

}

/* Function for finding saved registers in a 'struct pv_area'; this

   function is passed to pv_area_scan.

   If VALUE is a saved register, ADDR says it was saved at a constant

   offset from the frame base, and SIZE indicates that the whole

   register was saved, record its offset.  */

static void

check_for_saved (void *result_untyped, pv_t addr, CORE_ADDR size, pv_t value)

{

  struct rx_prologue *result = (struct rx_prologue *) result_untyped;

  if (value.kind == pvk_register

      && value.k == 0

      && pv_is_register (addr, RX_SP_REGNUM)

      && size == register_size (target_gdbarch, value.reg))

    result->reg_offset[value.reg] = addr.k;

}

/* Define a "handle" struct for fetching the next opcode.  */

struct rx_get_opcode_byte_handle

{

  CORE_ADDR pc;

};

/* Fetch a byte on behalf of the opcode decoder.  HANDLE contains

   the memory address of the next byte to fetch.  If successful,

   the address in the handle is updated and the byte fetched is

   returned as the value of the function.  If not successful, -1

   is returned.  */

static int

rx_get_opcode_byte (void *handle)

{

  struct rx_get_opcode_byte_handle *opcdata = handle;

  int status;

  gdb_byte byte;

  status = target_read_memory (opcdata->pc, &byte, 1);

  if (status == 0)

    {

      opcdata->pc += 1;

      return byte;

    }

  else

    return -1;

}

/* Analyze a prologue starting at START_PC, going no further than

   LIMIT_PC.  Fill in RESULT as appropriate.  */

static void

rx_analyze_prologue (CORE_ADDR start_pc,

                     CORE_ADDR limit_pc, struct rx_prologue *result)

{

  CORE_ADDR pc, next_pc;

  int rn;

  pv_t reg[RX_NUM_REGS];

  struct pv_area *stack;

  struct cleanup *back_to;

  CORE_ADDR after_last_frame_setup_insn = start_pc;

  memset (result, 0, sizeof (*result));

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

    {

      reg[rn] = pv_register (rn, 0);

      result->reg_offset[rn] = 1;

    }

  stack = make_pv_area (RX_SP_REGNUM, gdbarch_addr_bit (target_gdbarch));

  back_to = make_cleanup_free_pv_area (stack);

  /* The call instruction has saved the return address on the stack.  */

  reg[RX_SP_REGNUM] = pv_add_constant (reg[RX_SP_REGNUM], -4);

  pv_area_store (stack, reg[RX_SP_REGNUM], 4, reg[RX_PC_REGNUM]);

  pc = start_pc;

  while (pc < limit_pc)

    {

      int bytes_read;

      struct rx_get_opcode_byte_handle opcode_handle;

      RX_Opcode_Decoded opc;

      opcode_handle.pc = pc;

      bytes_read = rx_decode_opcode (pc, &opc, rx_get_opcode_byte,

                                     &opcode_handle);

      next_pc = pc + bytes_read;

      if (opc.id == RXO_pushm   /* pushm r1, r2 */

          && opc.op[1].type == RX_Operand_Register

          && opc.op[2].type == RX_Operand_Register)

        {

          int r1, r2;

          int r;

          r1 = opc.op[1].reg;

          r2 = opc.op[2].reg;

          for (r = r2; r >= r1; r--)

            {

              reg[RX_SP_REGNUM] = pv_add_constant (reg[RX_SP_REGNUM], -4);

              pv_area_store (stack, reg[RX_SP_REGNUM], 4, reg[r]);

            }

          after_last_frame_setup_insn = next_pc;

        }

      else if (opc.id == RXO_mov        /* mov.l rdst, rsrc */

               && opc.op[0].type == RX_Operand_Register

               && opc.op[1].type == RX_Operand_Register

               && opc.size == RX_Long)

        {

          int rdst, rsrc;

          rdst = opc.op[0].reg;

          rsrc = opc.op[1].reg;

          reg[rdst] = reg[rsrc];

          if (rdst == RX_FP_REGNUM && rsrc == RX_SP_REGNUM)

            after_last_frame_setup_insn = next_pc;

        }

      else if (opc.id == RXO_mov        /* mov.l rsrc, [-SP] */

               && opc.op[0].type == RX_Operand_Predec

               && opc.op[0].reg == RX_SP_REGNUM

               && opc.op[1].type == RX_Operand_Register

               && opc.size == RX_Long)

        {

          int rsrc;

          rsrc = opc.op[1].reg;

          reg[RX_SP_REGNUM] = pv_add_constant (reg[RX_SP_REGNUM], -4);

          pv_area_store (stack, reg[RX_SP_REGNUM], 4, reg[rsrc]);

          after_last_frame_setup_insn = next_pc;

        }

      else if (opc.id == RXO_add        /* add #const, rsrc, rdst */

               && opc.op[0].type == RX_Operand_Register

               && opc.op[1].type == RX_Operand_Immediate

               && opc.op[2].type == RX_Operand_Register)

        {

          int rdst = opc.op[0].reg;

          int addend = opc.op[1].addend;

          int rsrc = opc.op[2].reg;

          reg[rdst] = pv_add_constant (reg[rsrc], addend);

          /* Negative adjustments to the stack pointer or frame pointer

             are (most likely) part of the prologue.  */

          if ((rdst == RX_SP_REGNUM || rdst == RX_FP_REGNUM) && addend < 0)

            after_last_frame_setup_insn = next_pc;

        }

      else if (opc.id == RXO_mov

               && opc.op[0].type == RX_Operand_Indirect

               && opc.op[1].type == RX_Operand_Register

               && opc.size == RX_Long

               && (opc.op[0].reg == RX_SP_REGNUM

                   || opc.op[0].reg == RX_FP_REGNUM)

               && (RX_R1_REGNUM <= opc.op[1].reg

                   && opc.op[1].reg <= RX_R4_REGNUM))

        {

          /* This moves an argument register to the stack.  Don't

             record it, but allow it to be a part of the prologue.  */

        }

      else if (opc.id == RXO_branch

               && opc.op[0].type == RX_Operand_Immediate

               && opc.op[1].type == RX_Operand_Condition

               && next_pc < opc.op[0].addend)

        {

          /* When a loop appears as the first statement of a function

             body, gcc 4.x will use a BRA instruction to branch to the

             loop condition checking code.  This BRA instruction is

             marked as part of the prologue.  We therefore set next_pc

             to this branch target and also stop the prologue scan.

             The instructions at and beyond the branch target should

             no longer be associated with the prologue.

             Note that we only consider forward branches here.  We

             presume that a forward branch is being used to skip over

             a loop body.

             A backwards branch is covered by the default case below.

             If we were to encounter a backwards branch, that would

             most likely mean that we've scanned through a loop body.

             We definitely want to stop the prologue scan when this

             happens and that is precisely what is done by the default

             case below.  */

          after_last_frame_setup_insn = opc.op[0].addend;

          break;                /* Scan no further if we hit this case.  */

        }

      else

        {

          /* Terminate the prologue scan.  */

          break;

        }

      pc = next_pc;

    }

  /* Is the frame size (offset, really) a known constant?  */

  if (pv_is_register (reg[RX_SP_REGNUM], RX_SP_REGNUM))

    result->frame_size = reg[RX_SP_REGNUM].k;

  /* Was the frame pointer initialized?  */

  if (pv_is_register (reg[RX_FP_REGNUM], RX_SP_REGNUM))

    {

      result->has_frame_ptr = 1;

      result->frame_ptr_offset = reg[RX_FP_REGNUM].k;

    }

  /* Record where all the registers were saved.  */

  pv_area_scan (stack, check_for_saved, (void *) result);

  result->prologue_end = after_last_frame_setup_insn;

  do_cleanups (back_to);

}

/* Implement the "skip_prologue" gdbarch method.  */

static CORE_ADDR

rx_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)

{

  char *name;

  CORE_ADDR func_addr, func_end;

  struct rx_prologue p;

  /* Try to find the extent of the function that contains PC.  */

  if (!find_pc_partial_function (pc, &name, &func_addr, &func_end))

    return pc;

  rx_analyze_prologue (pc, func_end, &p);

  return p.prologue_end;

}

/* Given a frame described by THIS_FRAME, decode the prologue of its

   associated function if there is not cache entry as specified by

   THIS_PROLOGUE_CACHE.  Save the decoded prologue in the cache and

   return that struct as the value of this function.  */

static struct rx_prologue *

rx_analyze_frame_prologue (struct frame_info *this_frame,

                           void **this_prologue_cache)

{

  if (!*this_prologue_cache)

    {

      CORE_ADDR func_start, stop_addr;

      *this_prologue_cache = FRAME_OBSTACK_ZALLOC (struct rx_prologue);

      func_start = get_frame_func (this_frame);

      stop_addr = get_frame_pc (this_frame);

      /* If we couldn't find any function containing the PC, then

         just initialize the prologue cache, but don't do anything.  */

      if (!func_start)

        stop_addr = func_start;

      rx_analyze_prologue (func_start, stop_addr, *this_prologue_cache);

    }

  return *this_prologue_cache;

}

/* Given the next frame and a prologue cache, return this frame's

   base.  */

static CORE_ADDR

rx_frame_base (struct frame_info *this_frame, void **this_prologue_cache)

{

  struct rx_prologue *p

    = rx_analyze_frame_prologue (this_frame, this_prologue_cache);

  /* In functions that use alloca, the distance between the stack

     pointer and the frame base varies dynamically, so we can't use

     the SP plus static information like prologue analysis to find the

     frame base.  However, such functions must have a frame pointer,

     to be able to restore the SP on exit.  So whenever we do have a

     frame pointer, use that to find the base.  */

  if (p->has_frame_ptr)

    {

      CORE_ADDR fp = get_frame_register_unsigned (this_frame, RX_FP_REGNUM);

      return fp - p->frame_ptr_offset;

    }

  else

    {

      CORE_ADDR sp = get_frame_register_unsigned (this_frame, RX_SP_REGNUM);

      return sp - p->frame_size;

    }

}

/* Implement the "frame_this_id" method for unwinding frames.  */

static void

rx_frame_this_id (struct frame_info *this_frame,

                  void **this_prologue_cache, struct frame_id *this_id)

{

  *this_id = frame_id_build (rx_frame_base (this_frame, this_prologue_cache),

                             get_frame_func (this_frame));

}

/* Implement the "frame_prev_register" method for unwinding frames.  */

static struct value *

rx_frame_prev_register (struct frame_info *this_frame,

                        void **this_prologue_cache, int regnum)

{

  struct rx_prologue *p

    = rx_analyze_frame_prologue (this_frame, this_prologue_cache);

  CORE_ADDR frame_base = rx_frame_base (this_frame, this_prologue_cache);

  int reg_size = register_size (get_frame_arch (this_frame), regnum);

  if (regnum == RX_SP_REGNUM)

    return frame_unwind_got_constant (this_frame, regnum, frame_base);

  /* If prologue analysis says we saved this register somewhere,

     return a description of the stack slot holding it.  */

  else if (p->reg_offset[regnum] != 1)

    return frame_unwind_got_memory (this_frame, regnum,

                                    frame_base + p->reg_offset[regnum]);

  /* Otherwise, presume we haven't changed the value of this

     register, and get it from the next frame.  */

  else

    return frame_unwind_got_register (this_frame, regnum, regnum);

}

static const struct frame_unwind rx_frame_unwind = {

  NORMAL_FRAME,

  rx_frame_this_id,

  rx_frame_prev_register,

  NULL,

  default_frame_sniffer

};

/* Implement the "unwind_pc" gdbarch method.  */

static CORE_ADDR

rx_unwind_pc (struct gdbarch *gdbarch, struct frame_info *this_frame)

{

  ULONGEST pc;

  pc = frame_unwind_register_unsigned (this_frame, RX_PC_REGNUM);

  return pc;

}

/* Implement the "unwind_sp" gdbarch method.  */

static CORE_ADDR

rx_unwind_sp (struct gdbarch *gdbarch, struct frame_info *this_frame)

{

  ULONGEST sp;

  sp = frame_unwind_register_unsigned (this_frame, RX_SP_REGNUM);

  return sp;

}

/* Implement the "dummy_id" gdbarch method.  */

static struct frame_id

rx_dummy_id (struct gdbarch *gdbarch, struct frame_info *this_frame)

{

  return

    frame_id_build (get_frame_register_unsigned (this_frame, RX_SP_REGNUM),

                    get_frame_pc (this_frame));

}

/* Implement the "push_dummy_call" gdbarch method.  */

static CORE_ADDR

rx_push_dummy_call (struct gdbarch *gdbarch, struct value *function,

                    struct regcache *regcache, CORE_ADDR bp_addr, int nargs,

                    struct value **args, CORE_ADDR sp, int struct_return,

                    CORE_ADDR struct_addr)

{

  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);

  int write_pass;

  int sp_off = 0;

  CORE_ADDR cfa;

  int num_register_candidate_args;

  struct type *func_type = value_type (function);

  /* Dereference function pointer types.  */

  while (TYPE_CODE (func_type) == TYPE_CODE_PTR)

    func_type = TYPE_TARGET_TYPE (func_type);

  /* The end result had better be a function or a method.  */

  gdb_assert (TYPE_CODE (func_type) == TYPE_CODE_FUNC

              || TYPE_CODE (func_type) == TYPE_CODE_METHOD);

  /* Functions with a variable number of arguments have all of their

     variable arguments and the last non-variable argument passed

     on the stack.

     Otherwise, we can pass up to four arguments on the stack.

     Once computed, we leave this value alone.  I.e. we don't update

     it in case of a struct return going in a register or an argument

     requiring multiple registers, etc.  We rely instead on the value

     of the ``arg_reg'' variable to get these other details correct.  */

  if (TYPE_VARARGS (func_type))

    num_register_candidate_args = TYPE_NFIELDS (func_type) - 1;

  else

    num_register_candidate_args = 4;

  /* We make two passes; the first does the stack allocation,

     the second actually stores the arguments.  */

  for (write_pass = 0; write_pass <= 1; write_pass++)

    {

      int i;

      int arg_reg = RX_R1_REGNUM;

      if (write_pass)

        sp = align_down (sp - sp_off, 4);

      sp_off = 0;

      if (struct_return)

        {

          struct type *return_type = TYPE_TARGET_TYPE (func_type);

          gdb_assert (TYPE_CODE (return_type) == TYPE_CODE_STRUCT

                      || TYPE_CODE (func_type) == TYPE_CODE_UNION);

          if (TYPE_LENGTH (return_type) > 16

              || TYPE_LENGTH (return_type) % 4 != 0)

            {

              if (write_pass)

                regcache_cooked_write_unsigned (regcache, RX_R15_REGNUM,

                                                struct_addr);

            }

        }

      /* Push the arguments.  */

      for (i = 0; i < nargs; i++)

        {

          struct value *arg = args[i];

          const gdb_byte *arg_bits = value_contents_all (arg);

          struct type *arg_type = check_typedef (value_type (arg));

          ULONGEST arg_size = TYPE_LENGTH (arg_type);

          if (i == 0 && struct_addr != 0 && !struct_return

              && TYPE_CODE (arg_type) == TYPE_CODE_PTR

              && extract_unsigned_integer (arg_bits, 4,

                                           byte_order) == struct_addr)

            {

              /* This argument represents the address at which C++ (and

                 possibly other languages) store their return value.

                 Put this value in R15.  */

              if (write_pass)

                regcache_cooked_write_unsigned (regcache, RX_R15_REGNUM,

                                                struct_addr);

            }

          else if (TYPE_CODE (arg_type) != TYPE_CODE_STRUCT

                   && TYPE_CODE (arg_type) != TYPE_CODE_UNION)

            {

              /* Argument is a scalar.  */

              if (arg_size == 8)

                {

                  if (i < num_register_candidate_args

                      && arg_reg <= RX_R4_REGNUM - 1)

                    {

                      /* If argument registers are going to be used to pass

                         an 8 byte scalar, the ABI specifies that two registers

                         must be available.  */

                      if (write_pass)

                        {

                          regcache_cooked_write_unsigned (regcache, arg_reg,

                                                          extract_unsigned_integer

                                                          (arg_bits, 4,

                                                           byte_order));

                          regcache_cooked_write_unsigned (regcache,

                                                          arg_reg + 1,

                                                          extract_unsigned_integer

                                                          (arg_bits + 4, 4,

                                                           byte_order));

                        }

                      arg_reg += 2;

                    }

                  else

                    {

                      sp_off = align_up (sp_off, 4);

                      /* Otherwise, pass the 8 byte scalar on the stack.  */

                      if (write_pass)

                        write_memory (sp + sp_off, arg_bits, 8);

                      sp_off += 8;

                    }

                }

              else

                {

                  ULONGEST u;

                  gdb_assert (arg_size <= 4);

                  u =

                    extract_unsigned_integer (arg_bits, arg_size, byte_order);

                  if (i < num_register_candidate_args

                      && arg_reg <= RX_R4_REGNUM)

                    {

                      if (write_pass)

                        regcache_cooked_write_unsigned (regcache, arg_reg, u);

                      arg_reg += 1;

                    }

                  else

                    {

                      int p_arg_size = 4;

                      if (TYPE_PROTOTYPED (func_type)

                          && i < TYPE_NFIELDS (func_type))

                        {

                          struct type *p_arg_type =

                            TYPE_FIELD_TYPE (func_type, i);

                          p_arg_size = TYPE_LENGTH (p_arg_type);

                        }

                      sp_off = align_up (sp_off, p_arg_size);

                      if (write_pass)

                        write_memory_unsigned_integer (sp + sp_off,

                                                       p_arg_size, byte_order,

                                                       u);

                      sp_off += p_arg_size;

                    }

                }

            }

          else

            {

              /* Argument is a struct or union.  Pass as much of the struct

                 in registers, if possible.  Pass the rest on the stack.  */

              while (arg_size > 0)

                {

                  if (i < num_register_candidate_args

                      && arg_reg <= RX_R4_REGNUM

                      && arg_size <= 4 * (RX_R4_REGNUM - arg_reg + 1)

                      && arg_size % 4 == 0)

                    {

                      int len = min (arg_size, 4);

                      if (write_pass)

                        regcache_cooked_write_unsigned (regcache, arg_reg,

                                                        extract_unsigned_integer

                                                        (arg_bits, len,

                                                         byte_order));

                      arg_bits += len;

                      arg_size -= len;

                      arg_reg++;

                    }

                  else

                    {

                      sp_off = align_up (sp_off, 4);

                      if (write_pass)

                        write_memory (sp + sp_off, arg_bits, arg_size);

                      sp_off += align_up (arg_size, 4);

                      arg_size = 0;

                    }

                }

            }

        }

    }

  /* Keep track of the stack address prior to pushing the return address.

     This is the value that we'll return.  */

  cfa = sp;

  /* Push the return address.  */

  sp = sp - 4;

  write_memory_unsigned_integer (sp, 4, byte_order, bp_addr);

  /* Update the stack pointer.  */

  regcache_cooked_write_unsigned (regcache, RX_SP_REGNUM, sp);

  return cfa;

}

/* Implement the "return_value" gdbarch method.  */

static enum return_value_convention

rx_return_value (struct gdbarch *gdbarch,

                 struct type *func_type,

                 struct type *valtype,

                 struct regcache *regcache,