cris.c

gcc-you can use this code to learn something about gcc, and inquire further into linux,

/* Definitions for GCC.  Part of the machine description for CRIS.
   Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
   Contributed by Axis Communications.  Written by Hans-Peter Nilsson.

This file is part of GCC.

GCC 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, or (at your option)
any later version.

GCC 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 GCC; see the file COPYING.  If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

#include "config.h"
#include "system.h"
#include "rtl.h"
#include "regs.h"
#include "hard-reg-set.h"
#include "real.h"
#include "insn-config.h"
#include "conditions.h"
#include "insn-attr.h"
#include "flags.h"
#include "tree.h"
#include "expr.h"
#include "except.h"
#include "function.h"
#include "toplev.h"
#include "recog.h"
#include "tm_p.h"
#include "debug.h"
#include "output.h"
#include "target.h"
#include "target-def.h"
#include "ggc.h"

/* Usable when we have an amount to add or subtract, and want the
   optimal size of the insn.  */
#define ADDITIVE_SIZE_MODIFIER(size) \
 ((size) <= 63 ? "q" : (size) <= 255 ? "u.b" : (size) <= 65535 ? "u.w" : ".d")

#define ASSERT_PLT_UNSPEC(x)					\
  do								\
    {								\
      if (XEXP (x, 1) != NULL_RTX				\
	  || (GET_CODE (XVECEXP (x, 0, 0)) != SYMBOL_REF	\
	      && GET_CODE (XVECEXP (x, 0, 0)) != LABEL_REF))	\
	abort ();						\
    } while (0)

#define LOSE_AND_RETURN(msgid, x)			\
  do						\
    {						\
      cris_operand_lossage (msgid, x);		\
      return;					\
    } while (0)

/* Per-function machine data.  */
struct machine_function GTY(())
 {
   int needs_return_address_on_stack;
 };

/* This little fix suppresses the 'u' or 's' when '%e' in assembly
   pattern.  */
static char cris_output_insn_is_bound = 0;

/* This one suppresses printing out the "rPIC+" in
   "rPIC+sym:GOTOFF+offset" when doing PIC.  For a PLT symbol, it
   suppresses outputting it as [rPIC+sym:GOTPLT] and outputs similarly
   just the "sym:GOTOFF" part.  */
static int cris_pic_sympart_only = 0;

/* Fix for reg_overlap_mentioned_p.  */
static int cris_reg_overlap_mentioned_p PARAMS ((rtx, rtx));

static void cris_print_base PARAMS ((rtx, FILE *));

static void cris_print_index PARAMS ((rtx, FILE *));

static struct machine_function * cris_init_machine_status PARAMS ((void));

static int cris_initial_frame_pointer_offset PARAMS ((void));

static int saved_regs_mentioned PARAMS ((rtx));

static void cris_target_asm_function_prologue
  PARAMS ((FILE *, HOST_WIDE_INT));

static void cris_target_asm_function_epilogue
  PARAMS ((FILE *, HOST_WIDE_INT));

static void cris_encode_section_info PARAMS ((tree, int));
static void cris_operand_lossage PARAMS ((const char *, rtx));

static void cris_asm_output_mi_thunk
  PARAMS ((FILE *, tree, HOST_WIDE_INT, HOST_WIDE_INT, tree));


/* The function cris_target_asm_function_epilogue puts the last insn to
   output here.  It always fits; there won't be a symbol operand.  Used in
   delay_slots_for_epilogue and function_epilogue.  */
static char save_last[80];

/* This is the argument from the "-max-stack-stackframe=" option.  */
const char *cris_max_stackframe_str;

/* This is the argument from the "-march=" option.  */
const char *cris_cpu_str;

/* This is the argument from the "-mtune=" option.  */
const char *cris_tune_str;

/* This is the argument from the "-melinux-stacksize=" option.  */
const char *cris_elinux_stacksize_str;

/* This is the parsed result of the "-max-stack-stackframe=" option.  If
   it (still) is zero, then there was no such option given.  */
int cris_max_stackframe = 0;

/* This is the parsed result of the "-march=" option, if given.  */
int cris_cpu_version = CRIS_DEFAULT_CPU_VERSION;

#undef TARGET_ASM_ALIGNED_HI_OP
#define TARGET_ASM_ALIGNED_HI_OP "\t.word\t"
#undef TARGET_ASM_ALIGNED_SI_OP
#define TARGET_ASM_ALIGNED_SI_OP "\t.dword\t"
#undef TARGET_ASM_ALIGNED_DI_OP
#define TARGET_ASM_ALIGNED_DI_OP "\t.quad\t"

/* We need to define these, since the 2byte, 4byte, 8byte op:s are only
   available in ELF.  These "normal" pseudos do not have any alignment
   constraints or side-effects.  */
#undef TARGET_ASM_UNALIGNED_HI_OP
#define TARGET_ASM_UNALIGNED_HI_OP TARGET_ASM_ALIGNED_HI_OP

#undef TARGET_ASM_UNALIGNED_SI_OP
#define TARGET_ASM_UNALIGNED_SI_OP TARGET_ASM_ALIGNED_SI_OP

#undef TARGET_ASM_UNALIGNED_DI_OP
#define TARGET_ASM_UNALIGNED_DI_OP TARGET_ASM_ALIGNED_DI_OP

#undef TARGET_ASM_FUNCTION_PROLOGUE
#define TARGET_ASM_FUNCTION_PROLOGUE cris_target_asm_function_prologue

#undef TARGET_ASM_FUNCTION_EPILOGUE
#define TARGET_ASM_FUNCTION_EPILOGUE cris_target_asm_function_epilogue

#undef TARGET_ENCODE_SECTION_INFO
#define TARGET_ENCODE_SECTION_INFO cris_encode_section_info

#undef TARGET_ASM_OUTPUT_MI_THUNK
#define TARGET_ASM_OUTPUT_MI_THUNK cris_asm_output_mi_thunk
#undef TARGET_ASM_CAN_OUTPUT_MI_THUNK
#define TARGET_ASM_CAN_OUTPUT_MI_THUNK default_can_output_mi_thunk_no_vcall

struct gcc_target targetm = TARGET_INITIALIZER;

/* Predicate functions.  */

/* This checks a part of an address, the one that is not a plain register
   for an addressing mode using BDAP.
   Allowed operands is either:
   a) a register
   b) a CONST operand (but not a symbol when generating PIC)
   c) a [r] or [r+] in SImode, or sign-extend from HI or QI.  */

int
cris_bdap_operand (op, mode)
     rtx op;
     enum machine_mode mode;
{
  register enum rtx_code code = GET_CODE (op);

  if (mode != SImode && (mode != VOIDmode || GET_MODE (op) != VOIDmode))
    return 0;

  /* Just return whether this is a simple register or constant.  */
  if (register_operand (op, mode)
      || (CONSTANT_P (op) && !(flag_pic && cris_symbol (op))))
    return 1;

  /* Is it a [r] or possibly a [r+]?  */
  if (code == MEM)
    {
      rtx tem = XEXP (op, 0);

      if (mode == SImode
	  && (register_operand (tem, SImode)
	      || (GET_CODE (tem) == POST_INC
		  && register_operand (XEXP (tem, 0), SImode))))
	return 1;
      else
	return 0;
    }

  /* Perhaps a sign-extended mem: [r].(b|w) or [r+].(b|w)?  */
  if (code == SIGN_EXTEND)
    {
      rtx tem = XEXP (op, 0);

      if (GET_CODE (tem) != MEM)
	return 0;

      tem = XEXP (tem, 0);
      if (mode == SImode
	  && (register_operand (tem, SImode)
	      || (GET_CODE (tem) == POST_INC
		  && register_operand (XEXP (tem, 0), SImode))))
	return 1;
      else
	return 0;
    }

  return 0;
}

/* This is similar to cris_bdap_operand:
   It checks a part of an address, the one that is not a plain register
   for an addressing mode using BDAP *or* BIAP.
   Allowed operands is either:
   a) a register
   b) a CONST operand (but not a symbol when generating PIC)
   c) a mult of (1, 2 or 4) and a register
   d) a [r] or [r+] in SImode, or sign-extend from HI or QI.  */

int
cris_bdap_biap_operand (op, mode)
     rtx op;
     enum machine_mode mode;
{
  register enum rtx_code code = GET_CODE (op);
  rtx reg;
  rtx val;

  /* Check for bdap operand.  */
  if (cris_bdap_operand (op, mode))
    return 1;

  if (mode != SImode && (mode != VOIDmode || GET_MODE (op) != VOIDmode))
    return 0;

  /* Check that we're looking at a BIAP operand.  */
  if (code != MULT)
    return 0;

  /* Canonicalize register and multiplicand.  */
  if (GET_CODE (XEXP (op, 0)) == CONST_INT)
    {
      val = XEXP (op, 0);
      reg = XEXP (op, 1);
    }
  else
    {
      val = XEXP (op, 1);
      reg = XEXP (op, 0);
    }

  /* Check that the operands are correct after canonicalization.  */
  if (! register_operand (reg, SImode) || GET_CODE (val) != CONST_INT)
    return 0;

  /* Check that the multiplicand has a valid value.  */
  if ((code == MULT
       && (INTVAL (val) == 1 || INTVAL (val) == 2 || INTVAL (val) == 4)))
    return 1;

  return 0;
}

/* Check if MODE is same as mode for X, and X is PLUS, MINUS, IOR or
   AND or UMIN.  */

int
cris_orthogonal_operator (x, mode)
     rtx x;
     enum machine_mode mode;
{
  enum rtx_code code = GET_CODE (x);

  if (mode == VOIDmode)
    mode = GET_MODE (x);

  return (GET_MODE (x) == mode
	  && (code == PLUS || code == MINUS
	      || code == IOR || code == AND || code == UMIN));
}

/* Check if MODE is same as mode for X, and X is PLUS, IOR or AND or
   UMIN.  */

int
cris_commutative_orth_op (x, mode)
     rtx x;
     enum machine_mode mode;
{
  enum rtx_code code = GET_CODE (x);

  if (mode == VOIDmode)
    mode = GET_MODE (x);

  return (GET_MODE (x) == mode &&
	  (code == PLUS
	   || code == IOR || code == AND || code == UMIN));
}

/* Check if MODE is same as mode for X, and X is PLUS or MINUS or UMIN.  */

int
cris_operand_extend_operator (x, mode)
     rtx x;
     enum machine_mode mode;
{
  enum rtx_code code = GET_CODE (x);

  if (mode == VOIDmode)
    mode = GET_MODE (x);

  return (GET_MODE (x) == mode
	  && (code == PLUS || code == MINUS || code == UMIN));
}

/* Check if MODE is same as mode for X, and X is PLUS or MINUS.  */

int
cris_additive_operand_extend_operator (x, mode)
     rtx x;
     enum machine_mode mode;
{
  enum rtx_code code = GET_CODE (x);

  if (mode == VOIDmode)
    mode = GET_MODE (x);

  return (GET_MODE (x) == mode
	  && (code == PLUS || code == MINUS));
}

/* Check to see if MODE is same as mode for X, and X is SIGN_EXTEND or
   ZERO_EXTEND.  */

int
cris_extend_operator (x, mode)
     rtx x;
     enum machine_mode mode;
{
  enum rtx_code code = GET_CODE (x);

  if (mode == VOIDmode)
    mode = GET_MODE (x);

  return
    (GET_MODE (x) == mode && (code == SIGN_EXTEND || code == ZERO_EXTEND));
}

/* Check to see if MODE is same as mode for X, and X is PLUS or BOUND.  */

int
cris_plus_or_bound_operator (x, mode)
     rtx x;
     enum machine_mode mode;
{
  enum rtx_code code = GET_CODE (x);

  if (mode == VOIDmode)
    mode = GET_MODE (x);

  return
    (GET_MODE (x) == mode && (code == UMIN || code == PLUS));
}

/* Since with -fPIC, not all symbols are valid PIC symbols or indeed
   general_operands, we have to have a predicate that matches it for the
   "movsi" expander.  */

int
cris_general_operand_or_symbol (op, mode)
     rtx op;
     enum machine_mode mode;
{
  return general_operand (op, mode)
    || (CONSTANT_P (op) && cris_symbol (op));
}

/* Since a PIC symbol without a GOT entry is not a general_operand, we
   have to have a predicate that matches it.  We use this in the expanded
   "movsi" anonymous pattern for PIC symbols.  */

int
cris_general_operand_or_gotless_symbol (op, mode)
     rtx op;
     enum machine_mode mode;
{
  return general_operand (op, mode)
    || (CONSTANT_P (op) && cris_gotless_symbol (op));
}

/* Since a PLT symbol is not a general_operand, we have to have a
   predicate that matches it when we need it.  We use this in the expanded
   "call" and "call_value" anonymous patterns.  */

int
cris_general_operand_or_plt_symbol (op, mode)
     rtx op;
     enum machine_mode mode;
{
  return general_operand (op, mode)
    || (GET_CODE (op) == CONST
	&& GET_CODE (XEXP (op, 0)) == UNSPEC
	&& !TARGET_AVOID_GOTPLT);
}

/* This matches a (MEM (general_operand)) or
   (MEM (cris_general_operand_or_symbol)).  The second one isn't a valid
   memory_operand, so we need this predicate to recognize call
   destinations before we change them to a PLT operand (by wrapping in
   UNSPEC 0).  */

int
cris_mem_call_operand (op, mode)
     rtx op;
     enum machine_mode mode;
{
  rtx xmem;

  if (GET_CODE (op) != MEM)
    return 0;

  if (memory_operand (op, mode))
    return 1;

  xmem = XEXP (op, 0);

  return cris_general_operand_or_symbol (xmem, GET_MODE (op));
}

/* The CONDITIONAL_REGISTER_USAGE worker.   */

void
cris_conditional_register_usage ()
{
  /* FIXME: This isn't nice.  We should be able to use that register for
     something else if the PIC table isn't needed.  */
  if (flag_pic)
    fixed_regs[PIC_OFFSET_TABLE_REGNUM]
      = call_used_regs[PIC_OFFSET_TABLE_REGNUM] = 1;
}

/* Return current_function_uses_pic_offset_table.  For use in cris.md,
   since some generated files do not include function.h.  */

int